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The ShipyardState of the Art Report

May 2000

The ShipyardState of the Art Report

May 2000

The Shipyard State of the Art Report

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C o n t e n t s

1. Executive Summary

Acknowledgment ................................................................................................... 1

Short Descriptions ................................................................................................ 3

2. Shipyard Production Process Technologies (SP-16 Panel)

Material ManagementMaterial Handling .............................................................................................. 10Monitoring and Tracking ................................................................................... 11Statusing ............................................................................................................ 12

Steel Outfitting Manufacturing and AssemblyBeveling .............................................................................................................. 13Cutting ............................................................................................................... 14Forming .............................................................................................................. 15Punching and Drilling ....................................................................................... 16Shaping............................................................................................................... 18Heating ............................................................................................................... 18Shearing ............................................................................................................. 19Sawing ................................................................................................................ 20Disposing ............................................................................................................ 21Recycling ............................................................................................................ 22Inspecting ........................................................................................................... 23Setting and Erecting .......................................................................................... 24Fixturing ............................................................................................................ 25Positioning .......................................................................................................... 26Grinding and Sanding........................................................................................ 26Washing and Cleaning ...................................................................................... 27Milling ................................................................................................................ 28Bending .............................................................................................................. 29Winding .............................................................................................................. 30Cable Pulling ...................................................................................................... 31


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C o n t e n t s (Continued)

Hydrostatic Testing ............................................................................................ 32Points of Contact ................................................................................................ 33

3. Welding Technologies (SP-7 Panel)Beveling .............................................................................................................. 34Fitting ................................................................................................................. 35Shielded Metal Arc Welding .............................................................................. 36Gas Metal Arc Welding ...................................................................................... 37Flux Cored Arc Welding .................................................................................... 38Submerged Arc Welding .................................................................................... 39Gas Tungsten Arc Welding ................................................................................ 40Stud Welding ...................................................................................................... 41Electrogas and Electroslag Welding .................................................................. 42Plasma Arc Welding ........................................................................................... 42Brazing ............................................................................................................... 43Laser Welding .................................................................................................... 44Electron Beam Welding ..................................................................................... 45Friction Stir Welding ......................................................................................... 46Resistance Welding ............................................................................................ 47Thermal Spraying .............................................................................................. 47Polymer Joining ................................................................................................. 48Robotics............................................................................................................... 49Automation ......................................................................................................... 50Non-Destructive Testing .................................................................................... 51Points of Contact ................................................................................................ 52

4. Surface Preparation & Coating Technologies (SP-3 Panel)Sequencing and Integration .............................................................................. 53Surface Preparation and Coating Process Control ........................................... 54Pre-Construction Priming ..................................................................................... 55Primary Surface Preparation ............................................................................ 57


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Secondary Surface Preparation ....................................................................... 58Liquid Coating ................................................................................................... 59Powder Coating .................................................................................................. 60Environmental Technologies ............................................................................. 61Quality Management ......................................................................................... 62Points of Contact ................................................................................................ 63

APPENDIX A - Table of Acronyms .......................................................................... A-1APPENDIX B - Contributors ..................................................................................... B-1APPENDIX C - Navy Manufacturing Technology Centers of Excellence ........ C-1

C o n t e n t s (Continued)


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F i g u r e s

Figures

2-1 Crane Lifting Aircraft Carrier Island House .......................................................... 112-2 30-Foot Burning Machine ........................................................................................ 142-3 Rolling Machine ....................................................................................................... 162-4 Drilling Asset ............................................................................................................ 172-5 Fixed Pin Jigs ........................................................................................................... 252-6 Milling Machine ....................................................................................................... 29

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S e c t i o n 1

Executive Summary

The Shipyard State of the Art (SOA) Report hasbeen developed in support of the U.S. NavyMARITECH Advanced Shipbuilding Enterprise (ASE)program. Three shipyard production-related MajorInitiative Panels were chartered by the ExecutiveControl Board of the National Shipbuilding ResearchProgram (NSRP) to produce this SOA annual report.The panels included Shipyard Production ProcessTechnologies (SP-16); Welding Technologies (SP-7);and Surface Preparation and Coating Technologies(SP-3). A team of representatives from U.S. shipyardsand the Navy Manufacturing Technology ProgramCenters of Excellence worked together to produce thereport, which focuses on shipyard production processesand related technologies. Government and industrygroups may use the report as a basis for comparingcurrent practices with SOA practices. The SOA reportalso strives to improve the U.S. industry in a mannerthat is consistent with the mission and vision of theMARITECH ASE program, as described below.

The U.S. Navy has worked with industry, theDefense Advanced Research Projects Agency, theMaritime Administration, and the U.S. Coast Guardto develop the MARITECH ASE program. Thisprogram is strategically structured to place industryin such a position so as to control its own destiny. Theshipbuilding industry strongly endorses this newprogram. The Executive Control Board of the NSRPtook the lead in forming the collaborativeorganizational structure required to develop andadminister a landmark, industry-wide strategic,research and development investment plan on a cost-share basis with government, funded by the U.S.Navy’s MARITECH ASE program. Participation inMARITECH ASE is open and accessible to the entiremaritime industry.

MISSION: The mission of MARITECH ASE andthe NSRP is to manage and focus national shipbuildingresearch and development funding on technologieswhich reduce the cost of warships to the U.S. Navyand foster U.S. international shipbuildingcompetitiveness.

VISION: Industry has developed a consensus vi-sion for U.S. shipbuilding as a common frame ofreference for collaborative, coordinated research and

development. By 2006 and through the collaborativedevelopment of product and process improvements,the U.S. shipbuilding industry will become a robust,self-sufficient industry that:

• Is recognized as able to build ships as efficientlyand cost effectively as world competitive shipyards,and has captured a significantly increased shareof commercial markets.

• Has significantly reduced the cost of ships to theU.S. Navy; adjusted to the substantial reductionin military construction; and preserved theinfrastructure support which the U.S. Navyshipbuilding needs for the foreseeable future.

• Continues to be characterized by customersatisfaction, safety, quality, environmentalcompliance, and increasingly lean cost and cycletime.

The SOA report is purposely structured to highlightproduction processes. It is divided into three chapters,one for each of the participating panels. Each DiscreteProcess write-up provides an Introduction; a State ofthe Industry; a State of the Art; a State of RelatedIndustry; an Enabling Technologies; and aManufacturing Strategies section. The MARITECHASE Strategic Investment Plan Sub-initiatives;Product Control; Industrial Engineering; OutfitFabrication/Installation/Test; Structural Fabrication/Subassembly/Assembly and Erection; ProductionControl; and Surface Preparation and Coatings wereused as a guide for SOA process selection. Thedevelopment team recognized the need to prioritizethe area of report development due to the broad scopeof shipyard production processes.

ACKNOWLEDGMENT

We would like to thank the Office of Naval Research,in particular Mr. Steve Linder, Director,Manufacturing Technology Program, for his supportof this effort to develop the first Shipyard ProductionProcess Technologies State of the Art Report. TheBest Manufacturing Practices Center of Excellence,Mr. Ernie Renner, Director, and Dr. Anne Marie T.SuPrise, Deputy Director, should also be recognizedfor their leadership, dedication, and commitment to

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producing a quality report in a short period of time.The active participation of the Gulf Coast RegionMaritime Technology Center, Institute forManufacturing and Sustainment Technologies,National Center for Excellence in MetalworkingTechnology, and Navy Joining Center have beencrucial to the success of this endeavor. The core teamof people who worked diligently to make this happen

Core Team Members:John Carney, Office of Naval ResearchTommy Cauthen, Ingalls ShipbuildingScott DeVinney, General Dynamics, Bath Iron

WorksSuren Dwivedi, University of LouisianaTom Hite, Applied Research Laboratory,

The Pennsylvania State UniversityLee Kvidahl, Ingalls ShipbuildingRick Nelson, General Dynamics,

Electric Boat CorporationMark Panosky, General Dynamics,

Electric Boat CorporationAllan Roy, Newport News ShipbuildingBart Sickles, Concurrent Technologies

CorporationCharles Tricou, Applied Research Laboratory,

The Pennsylvania State UniversityMatthew White, Navy Joining Center/

Edison Welding Institute

are listed below. Their dedication, persistence,leadership, and expertise are to be commended. Theirefforts will likely result in a Sate of the Art Reportconcept that can be improved upon and expanded toinclude the MARITECH ASE Major Initiatives in thefuture.

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Short Descriptions

SHIPYARD PRODUCTION PROCESSTECHNOLOGIES (SP-16 PANEL)(Material Management/Steel OutfittingManufacturing and Assembly)

MATERIAL MANAGEMENT

Material Handling 10

Material handling refers to the handling,storage, control, and flow of materialsthroughout a facility. A material handlingsystem provides efficient flow paths,coordinates supply and demand, minimizesdamaged goods, and maximizes storage space.The successful operation of any enterprisedepends to a great extent on an efficient andeffective system.

Monitoring and Tracking 11

Monitoring and tracking refers to systemsthat detect, follow, oversee, and/or record thelocation or state of material within a facility.Flexibility and integration are also valuablefeatures for continuous monitoring andtracking systems, enabling facilities to easilyadapt to new objectives and/or situations.

Statusing 12

Statusing refers to the timely andcomprehensive measuring of a progress,independent of calculating input or observingvariances. This operation involves periodicreviews of a process (e.g., material handling,monitoring, tracking) in terms of its currentstate/condition and the efficiency of its costfactors during execution. From this data,facilities can explore possible correctiveactions to improve their processes.

STEEL OUTFITTING MANUFACTURINGAND ASSEMBLY

Beveling 13

Beveling is a secondary operation that preparesmaterial surfaces for welding. To maintain

the adequate joint strength, welding engineersspecify joint geometries that can include avariety of single (top surface) or double (topand bottom surfaces) bevel designs. Producingappropriate bevel angles can be achieved byusing milling, grinding, or cutting machines.

Cutting 14

Cutting is the process by which structuraland outfitting piece parts are fabricated fromtheir raw stock material. For ferrous material,piece parts (e.g., hull, hull fittings, piping,foundations, machinery components) are cutusing a thermal cutting process such as oxy-fuel flame, plasma arc, or laser beam cutting.For plasma and oxy-fuel cutting, the torch ismoved along the cut path by a variety ofmeans including manually (hand torch),mechanized equipment, numerical controlmachines, and robotics.

Forming 15

Forming is a primary process in shipbuildingthat involves a variety of techniques and toolsto manufacture complex parts. Depending onthe material type and size, either cold or hotforming techniques can be used includingheating, pressing, rolling, knuckling, bending,or straightening. Achieving and maintainingdimensional accuracy is a critical requirementfor this process to minimize downstreamassembly costs.

Punching and Drilling 16

Punching and drilling are similar productionprocesses that create holes in substances byusing equipment to remove excess material.Punching uses forceful, repeated blows topierce through the material, while drillinguses cutting bits to bore through the material.Piece part fabrication relies on these processesto provide certain design details which cannotbe executed by other means.

Shaping 18

Shaping involves production processes thatenable the shipbuilder to create complex three-

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dimensional surfaces, generally from flat stockmaterial. The manufacture of irregular-shaped parts and the contouring of flat stockmaterials rely on a combination of severalprocesses such as cutting, sawing, beveling,and grinding.

Heating 18

Heating is a secondary process traditionallyreserved for material items that will undergoforming and straightening operations. Theapplication of the process involves pre-heatingmaterials either by using fixed ovens or bylocally applying the heat through manualmeans. Heating provides a way to relievestress or form materials depending on theirgrade, type, and thickness.

Shearing 19

Shearing is a more traditional process, oftenreserved for less complex materials, whereaccuracy is not a significant requirement.The process involves the sizing of specificmanufactured part dimensions by usingpowered hydraulic machines. These machinestear the base material along a single axismuch like scissors cutting paper. The edgetearing results in minor damage to themechanical properties of the base materialand, in some cases, diminishes the qualitynecessary for welding.

Sawing 20

Sawing involves the use of portable or poweredequipment that feature abrasive cutting disksor teeth in different grades or configurationsto remove material. The process is usuallyassociated with the fabrication or manufactureof finished and correctly sized piece parts.The process is applicable to virtually allmaterials across the entire shipbuildingprocess.

Disposing 21

Disposing involves the storage, handling,and containment control of a wide range ofbyproducts (solids, liquids, gases) produced

during shipbuilding operations. Themanaging of this wastestream is an integralpart of the shipbuilding industry’sresponsibility. Proper waste managementinvolves many aspects such as identifyingsafeguards; reducing hazardous exposure;and complying with environmental laws andregulations.

Recycling 22

Recycling involves the storage, handling,containment, and reuse of materials that arepart of the shipbuilding wastestream.Complying with local and regional regulationsas well as the challenge of converting thisportion of the industrial wastestream intorevenue are integral parts of the shipbuildingprocess.

Inspecting 23

Inspection within the shipbuilding industryrepresents one process with many facades.Whether it involves material receipt or shipsystem completion, inspection remains aniterative process that requires sophisticatedpractices similar to those in other industries.Inspection within the shipbuilding industrycan also involve highly specialized advancedtechnologies and services, especially in suchareas as manufacturing, assembly processes,and sea trials.

Setting and Erecting 24

Setting generally refers to a major evolutionin the assembly stage of shipbuilding wheresome combination of positioning and handlingoperations are involved. Setting and erectingtypically describe those activities thatcontribute to the final assembly of outfittedstructural blocks, the joining of whichcompletes the ship.

Fixturing 25

Fixturing involves a wide range of productionaides and ancillary equipment that facilitatepositioning, restraining, or manipulatingproduction material. Maintaining and

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controlling dimensional accuracy, whilereducing or minimizing mechanical distortion,necessitate a significant number ofmanufacturing and assembly fixturesthroughout the shipbuilding process. As anintegral part of the overall process, fixturingrequirements add to the scale and complexityof the entire process.

Positioning 26

Positioning, as a production process inshipbuilding, almost universally refers tothose methods involved in moving andorienting larger material items to perform aprimary or secondary operation. The processtypically involves loading/unloading work-in-process, and accurately positioningdimensional planes, features, or objectsrelative to a particular manufacturing orassembly work center. Positioning alsoembraces the methods and practices used toinstall components or large-scale, multi-tonobjects (e.g., outfitted platforms) bymanipulating the volume of required space tofit the volume of available space.

Grinding and Sanding 26

Grinding and sanding are similar processeswhich are prevalent throughout themanufacturing and assembly operations inthe shipbuilding industry. Typicallyperformed with stationary portable or poweredequipment, they are considered to be secondaryprocesses because they remove material aspart of a cleaning or preparatory step (e.g.,deburring; removing weld spatter, paint, orpaint primer). As a finishing or surfacingprocess, grinding refers to a more aggressiveoperation in which larger amounts of materialare removed. In cases of precision grinding,numerical control machinery is used toproduce fine finishes and/or close tolerances.

Washing and Cleaning 27

Washing and cleaning involves the use ofmild or aggressive chemical agents to achieveacceptable surface conditions as a prerequisitefor another process operation. These

production processes are used to eliminaterust, scale, oxidation, flux, grease, dust, and/or other foreign particulates. Cleaning certainmaterial types also secures a level ofpreservation consistent with expected lifecycle requirements.

Milling 28

Milling is a primary operation in shipbuildingthat provides surfacing, facing, and edgepreparation of various close tolerance pieceparts. The process is associated with thefabrication or manufacture of finished pieceparts requiring intricate accuracy obtainableonly with computerized numerical controlmachines. As a machining operation, millingmachines are capable of performing gougingor cutting in two axes of motionsimultaneously. Consumable cutting tips androtary cutters operate in a dry or self-lubricated system to remove material at fairlyhigh rates in a series of programmedtrajectories across the work piece.

Bending 29

Bending, as a production process inshipbuilding, almost universally refers to themanufacture of pipe piece parts. The processtypically involves loading and unloading stocklengths of pipe into hydraulically assistedcomputer numerical control bending machinesthat are capable of bending various wallthicknesses, material types, and diameters.Bending also refers to sheet metal piece partsthat are bent on press brake machines capableof creating a desired angle or bend.

Winding 30

Winding refers to the repair of electricalmotors that require periodic maintenance aspart of a comprehensive ship overhaul.Winding, also known as rewinding, involvesboth AC and DC motors of various sizes. Theprocess typically entails cleaning armaturesand stators; using solvent baths; coating orvarnishing armatures; and conducting visualinspections to maintain the integrity ofelectrical motors.

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Cable Pulling 31

Pulling (or installing) electrical cables thatsupport shipboard services involves a majorityof manual processes that have changed littleover time. Routing the wide range of electricalcable sizes that make up the ship’s power,communications, and generation services cantypically involve miles of cabling. A majorityof the electrical services for militarycombatants includes large diameter, highvoltage shielded cabling that runs hundredsof feet between connection points. Recentpractices have introduced fiber optic cablingfor low voltage communications systems.

Hydrostatic Testing 32

Hydrostatic testing (or hydro-testing) involvespressurizing specific ship components orsystems to determine and validate theirstructural integrity. Most piping systems onships are hydrostatically tested to 1.5 timestheir operating pressure before they are placedinto service. Testing involves isolating acomponent from adjacent ship systems (e.g.,tank or piping system); connecting andapplying air or water pressure; and identifyingpotential leaks using leak detection devices.The process is iterative until the completesystem achieves the required integrity.Testing guarantees system integrity and,ultimately, the crew’s and ship’s safety.

WELDING TECHNOLOGIES (SP-7 PANEL)

Beveling 34

Beveling is a process that prepares materialsurfaces (e.g., plate edges that form a joint)for welding to ensure a quality full penetrationweld or, in some cases, the correct depth ofpenetration. In addition, this angular edgepreparation permits greater access to the rootof the joint and easier manipulation of thewelding torch. Beveling is achieved for blockassembly, erection beams, and othersubsequent welding practices through milling,grinding, and cutting machines.

Fitting 35

Fitting is the alignment and placement ofparts to be welded. This process is one of themost important operations for cost effectivewelding. The overall dimensional accuracy ofship structures is directly related to theaccuracy and adequacy with which parts arealigned prior to welding and held in positionduring the welding operation.

Shielded Metal Arc Welding 36

Shielded metal arc welding is a process thatproduces coalescence of metals by heatingthem with an arc between a covered metalelectrode and the work pieces, and obtainsshielding from the decomposition of theelectrode covering. Although it is one of theoldest arc welding operations, this process isalso one of most durable for structural andpipe applications.

Gas Metal Arc Welding 37

Gas metal arc welding is a process thatproduces coalescence of metals by heatingthem with an arc between a continuous fillermetal electrode and the work pieces, andobtains shielding entirely from an externallysupplied gas. This process is a primary methodfor fabricating ship structures, and is usedextensively for piping and pressure vesselcomponents.

Flux Cored Arc Welding 38

Flux cored arc welding is a process thatproduces coalescence of metals by heatingthem with an arc between a continuous fillermetal electrode and the work pieces, andobtains all or partial shielding by a fluxcontained within the tubular electrode. Oneadvantage of this process is its ability to weldthrough pre-construction paint primers withan acceptable weld quality, making it theprocess of choice in many shipyards.

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Submerged Arc Welding 39

Submerged arc welding is a process thatproduces coalescence of metals by heatingthem with an arc (or arcs) between a baremetal electrode (or electrodes) and the workpieces, and obtains shielding by a blanket ofgranular, fusible material on the work piece.By using special equipment, shipyards haverefined this technique so that all welding canbe performed from one side and the cost ofturning completed panels is avoided.

Gas Tungsten Arc Welding 40

Gas tungsten arc welding is a process thatproduces coalescence of metals by heatingthem with an arc between a non-consumabletungsten electrode and the work pieces, andobtains shielding by a gas. The processproduces superior quality welds and can beused to weld almost any metal. Its ability toindependently control the heat source andfiller metal additions provides excellent controlof root pass weld penetration for criticalapplications.

Stud Welding 41

Stud welding is a process that producescoalescence of metals by heating them withan arc between a metal stud or similar partand the work pieces. This process can beperformed manually with the use of a hand-held welding gun or by mechanized equipmentfor high production applications.

Electrogas and Electroslag Welding 42

Electrogas welding is a process that producescoalescence of metals by heating them withan arc between a continuous filler metalelectrode and the work pieces. Electroslagwelding is a process that produces coalescenceof metals with molten slag that melts thefiller metal and the surfaces of the workpieces. Although their use is declining due tonew ship designs and alternative methods,these high deposition processes are gainingpopularity in the bridge and buildingconstruction industries.

Plasma Arc Welding 42

Plasma arc welding is a process that producescoalescence of metals by heating them with aconstricted arc between an electrode and thework piece (transferred arc), or between theelectrode and the constricting nozzle (non-transferred arc). Shielding is obtained fromthe hot, ionized gas issuing from the torchwhich may be supplemented by an auxiliarysource of shielding gas. This process hasproven to be very robust for high volumeautomation welding operations due to itsrecessed tungsten electrode, which provideslonger operating times.

Brazing 43

Brazing is a process that produces coalescenceof materials by heating them to the brazingtemperature in the presence of a filler metalhaving a liquidus above 840°F (450°C) andbelow the solidus of the base metal. Thisprocess differs from other joining methods inthat the brazing does not melt the base metalsbeing joined, thereby allowing dissimilar ordifficult-to-weld materials to be joined.

Laser Welding 44

Laser welding is a process that producescoalescence of materials with the heat obtainedfrom the application of a concentrated coherentlight beam impinging on the joint. The highspeed, low heat input, and precision of laserwelding result in low thermal distortion.With the advent of using fiber optics totransport the light beam to the work, ratherthan having the part move under the beam,possible applications for laser welding includein-situ repair work, beam to plate joints, andpipe welding.

Electron Beam Welding 45

Electron beam welding is a process thatproduces coalescence of metals with the heatobtained from a concentrated beam composedprimarily of high velocity electrons impingingon the joint. The process features three basicmethods: high vacuum; medium vacuum;and non-vacuum — the latter of which is themost practical in the shipbuilding industry.

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Friction Stir Welding 46

Friction stir welding is a solid-state processthat produces coalescence of materials underthe compressive contact force of a rotatingtool and the work pieces, moving relative toone another to produce heat and plasticallydisplace material from the faying surfaces.This process enables butt and lap joints to bemade in low melting point materials (e.g.,aluminum alloys) without the use of fillermetals.

Resistance Welding 47

Resistance welding is a process where thecoalescence of metals is produced by the heatgenerated by the resistance of the metal to thepassage of electric current. This process isideal for overlapping sheet metal connections.

Thermal Spraying 47

Thermal spraying is a process in which finelydivided metallic or nonmetallic surfacingmaterials are deposited in a molten or semi-molten condition on a substrate to form aspray deposit. The three most commonlyused methods are electric arc spraying; highvelocity oxy-fuel spraying; and atmosphericplasma spraying.

Polymer Joining 48

Polymer joining is a variety of processes usedto join polymer materials such as plastics andcomposites. The processes include adhesives;hot plate; hot gas; resistive and inductionimplant welding; friction welding; and laserand infrared welding. The selection of methodis dependent on the polymer chemistry, thejoint designs, and the service requirements.

Robotics 49

Robotics is the technology dealing with thedesign, construction, and operation of robotsin automation. A robot is an automaticallycontrolled, reprogrammable, multi-purposemanipulator that operates in three or moreaxes, and performs defined tasks within itsworking envelope. Design for automation and

continuous improvement in robotics arehelping to enhance and foster this technologyin many industries.

Automation 50

Automation is the technique of making anapparatus, a process, or a system operate by aself-regulating mechanism. Typical examplesof single-purpose mechanized automationinclude portable tractors, fixed dedicatedsystems, sensor technologies, and smallcomputer-based processors.

Non-Destructive Testing 51

Non-destructive testing refers to theinspection, analysis, or treatment of materialwithout damaging or altering its initial state.Typical methods include surface examination,volumetric examination, radiographic testing,and ultrasonic testing.

SURFACE PREPARATION AND COATINGTECHNOLOGIES (SP-3 PANEL)

Sequencing and Integration 53

The sequencing and integration of surfacepreparation and coating processes are criticalcomponents of the pre-construction planningfunction and build strategy. Each stage ofconstruction is carefully assessed and placedin balance with the product’s coatingspecifications. Since shipbuilding is anorchestration of multiple trade disciplines,these processes must also be properly blendedinto the overall scheme to optimizepreservation system performance and costefficiency.

Surface Preparation and Coating 54Process Control

Surface preparation and coating processcontrol is a management activity thatmonitors performance to budget, relative toprogress. Using this process, paintdepartment managers can perform ananalytical assessment of productivity ondiscrete work orders or labor charges.

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Pre-Construction Priming 55

Pre-construction priming refers to the processby which ferrous steel plates and shapes, asreceived from the mill, are preserved prior tofabrication. The primary objective of thisprocess is to reduce the cost of secondarysurface preparations in the later stages ofship construction.

Primary Surface Preparation 57

Primary surface preparation refers to thepreparation and painting of incomingstructural steel plates and shapes prior tofabrication. Mill scale and rust are removedusing centrifugal blasting equipment andrecyclable steel abrasives. The new steel isthen coated with a weld-through pre-construction primer to protect the surfacefrom corrosion and preserve the surface profileimparted during the cleaning process. Forshipyards that cannot use the weld-throughpre-construction primers, primary surfacepreparation refers to the initial blast cleaningof structures prior to coating.

Secondary Surface Preparation 58

Secondary surface preparation refers to there-preparation and re-painting of steelstructures during ship fabrication or repair.For new construction, this process is requiredfor welds and damaged areas after thestructures have been fabricated and prior tothe application of the final paint system.Abrasive blasting is usually used to removeold coatings and corrosion products as well asto impart a profile to the substrate. In caseswhere blasting is impractical, mechanicaltools are used instead. Consequently,improvements in tooling and coating systemscan reduce the costs and schedule impactfrom secondary surface preparation.

Liquid Coating 59

Liquid coating is the primary shipyard methodfor protecting structures, components, andpiping from corrosion. These coatings alsoprovide resistance to fouling; increase fireresistance; identify safety requirements; and

support habitability schemes. Application ofliquid coatings to ships is still very laborintensive and costly. However, state-of-the-art methods are available to reduce thesecosts and shorten preservation schedules.

Powder Coating 60

Powder coating is a process in which partiallycatalyzed resins and curing agents in a powderform are applied to metal parts, and thenbaked in an oven. The heat from the ovencauses the powder to liquefy, flow, gel, andharden — thereby making a uniformcontinuous film that is tough and durable.Powder coatings do not emit solvents to theenvironment, nor do they create hazardouswaste. The increased use of powder coatingsin shipyards can greatly reduce labor costsfor preservation as well as provide moredurable coating systems.

Environmental Technologies 61

Environmental technologies are used tocomply with federal, state, and localenvironmental regulations for air quality,water quality, and hazardous wastemanagement. These technologies also includemethods to control temperature, relativehumidity, dew point, solvent vaporconcentrations, and other similar conditionsduring surface preparation and coatingoperations. Environmental compliance andcontrol technologies can directly impactshipyard profits. Consequently, a variety oftechnical methods are available for meetingthese challenges.

Quality Management 62

Quality management is the process by whichthe quality of received coatings, surfacepreparations, coating applications, curing,and final acceptance is achieved. This processalso involves the training of paint shop andinspection personnel on quality attributes.Shipyard preservation costs can be reducedby developing clear and focused qualitymanagement programs, and by increasingthe level of computerization of the qualityprocess.

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CHAPTER SUMMARYIn this SOA report, steel outfitting manufacturing

and assembly addresses more than 20 discreteshipbuilding processes. The objective is to produce asingle source of information that provides an overviewof processes and a comparison with world-classpractices. For steel manufacturing and assemblywhich is the heart and soul of shipbuilding, the Stateof the Art is healthy. Despite lower volumes of steelthroughput compared to overseas competitors, U.S.shipbuilders are reasonable well equipped.Additionally, industry reflects a trend to purchaseservices outside of its more traditional role. Thetransition toward outsourcing is driven by a relianceon fewer U.S. Navy contracts and virtual nocommercial work. As a result, production practices inareas that traditionally manufacture piping,sheetmetal, electrical components, and painting havelost the expertise once common across the industry.

While technical advancements continue to affectthe information and data that drives production aswell as the hardware that steers productivity, thereare other less notable changes which are equallyimportant. Moving toward a green industry that isecologically more responsive to local communitieswill require vigilance and money. Powder coating asa production process will continue to gain favor, inlieu of traditional paint processes that release airborne contaminants. Reducing production costs forprocesses that ultimately drive customer contractpricing will hinge on eliminating non-value addedoperations. Increasing part and, therefore, assemblyaccuracy are critical to this objective. Currently,there are many production steps that can be considerediterative, largely due to the fit-and-finish qualities ofinterim products which eventually become the ship.Improvements in producing dimensionally accuratepiece parts during each step of the manufacturingprocess which reduces downstream assembly costsare vital in decreasing overall costs. Investments incutting, forming, joining, and inspection technologieswhich perform faster with greater accuracy willbecome necessary.

Strategies affecting the supply chain must becomeleaner by reducing inventory levels and work-in-process. Beginning with secondary sources that feedhigher tiers of the national supply chain as well aswithin the internal shipbuilding production processes,

just-in-time will become inevitable. Enterpriseresource planning and materials requirement planningwill continue to be the foundation for changes to theinternal functionality of the shipbuilder industry.Investments in computer-based modeling to simulatechanging circumstances will also provide informedfeedback for key business managers.

Material Management

Material Handling

INTRODUCTION:Material handling refers to the handling, storage,

control, and flow of materials throughout a facility.A material handling system provides efficient flowpaths, coordinates supply and demand, minimizesdamaged goods, and maximizes storage space. Pre-assembling the parts can also help reduce materialmovement costs. The successful operation of anyenterprise depends to a great extent on an efficientand effective system. In shipbuilding, material handlingaccounts for a substantial portion of the total shipconstruction cost.

STATE OF THE INDUSTRY:Material handling can be categorized into four

areas: (1) shop material handling, (2) ship blockmaterial handling, (3) ship movement, and (4)movement of small parts and tools in on-board andon-block environments. In shop material handling,the shops rely on forklift trucks, conveyors, andcranes to move material. In ship block materialhandling, the ship is assembled by using specialtransporters and cranes (Figure 2-1). In shipmovement, the ship/ship systems are moved by usingdry docks, tugboats, or pontoon launchers withtranslation rail systems. In the movement of smallparts and tools in on-board and on-block workenvironments, personnel travel from the work site toanother location to obtain these items.

STATE OF THE ART:Best material handling practices enable shipyards

to stationize personnel and minimize the use of lessefficient material handling schemes. Most shops

S e c t i o n 2

Shipyard Production Process Technologies (SP-16 Panel)

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extensively use power roller conveyors, robotics, andother automated material handling devices. In on-block work environments, larger capacity transportersand cranes provide the means for lifting large blocks,which reduces the number of trips needed to completeblock erection. In on-block work environments,material elevators, rather than cranes, are used fortransporting smaller loads. Additionally, supportservices (e.g., storerooms, tool rooms) are beingdesigned as moveable modules and placed near ships,thereby reducing the travel distances for materials.

STATE OF RELATED INDUSTRY:For this area, further evaluation and collaboration

is underway.

ENABLING TECHNOLOGIES:Simulation modeling is the most advanced tool of

material handling planning. This technology enablesshipyards to predict future material handlingbottlenecks. By resolving these obstacles, shipyards

can improve their resource utilization. Simulationmodeling is also used to monitor numerous materialhandling factors; review multiple options; and analyzethe cost impact of these options on the entire shipyardsystem. While it does not provide an optimum solution,simulation modeling does offer a platform for quickreview of proposed improvements.

MANUFACTURING STRATEGIES:An important methodology for improving material

handling involves the reduction of movementthroughout a shipyard. In a just-in-time (JIT) system,material is manufactured or delivered at the lastpossible moment; hence, the name. This strategyresults in reduced movement of material; less storagespace requirements; decreased occurrences of lost ordamaged material; and lower monitoring and trackingefforts for in-process storage. An immediate financialbenefit of using a JIT system is the availability ofoperating capital. Rather than tying up millions ofdollars in idle material at a shipyard in-process bank,this capital can be invested elsewhere.

Monitoring and Tracking

INTRODUCTION:Monitoring and tracking refers to systems that

detect, follow, oversee, and/or record the location orstate of material within a facility. Flexibility andintegration are also valuable features for continuousmonitoring and tracking systems, enabling facilitiesto easily adapt to new objectives and/or situations.

STATE OF THE INDUSTRY:The Automatic Tooling Inventory Control Tracking

System (ATICTS) was implemented during the 1980s.ATICTS can track usage and maintain inventorylevels which are initially set by the systemadministrator. By using this system, shipyards canidentify low inventory items as well as producereports that document usage and history. Among thetypes of reports generated by ATICTS are vendorhistory, unit prices, cost data, and daily issue fromtool areas. In addition to ATICTS, shipyards usebarcoding on component material to identify the lastlocation and process which the part has completed.This method can even locate parts in transit.

STATE OF THE ART:For this area, further evaluation and collaboration

is underway.

Figure 2-1. Crane Lifting Aircraft CarrierIsland House

12

STATE OF RELATED INDUSTRY:Heavy industry has developed a generic concept for

cell control based on information flow and functionalanalysis of operations for production cells. Known asROB-EX, this software control system offers usersmany functions and applications. Among them aretransfer-of-production data; detailed scheduling ofwork tasks; execution of work tasks; automatic dataacquisition; and monitoring which includesproduction reports.

ENABLING TECHNOLOGIES:Barcode scanning technology and computer

software products provide the means for monitoringand tracking tools and component material. Theentire process operation can be optimized by combiningease of performance with accurate on-line tracking ofassemblies and elements in production. ROB-EX hasalready demonstrated its usefulness in many industrialapplications and requirements. This software controlsystem facilitates the integration of heterogeneousproduction cells and systems within an organization.As a result, ROB-EX has great potential in theshipbuilding industry and its applications need to beexplored.

MANUFACTURING STRATEGIES:The foremost requirements of setting up better

monitoring and tracking systems are flexibility,integration, and distribution. Flexibility means thatthe system (e.g., information, control, inventory,accounting) can be quickly adapted to newcircumstances and that activities can be changed orre-engineered. The user should also be able to simulatethe impact. Integration means that the system can bemonitored in all aspects of design, and that theconstruction, outfitting, and impact of schedulingchanges at other shipyards can be assessed. Allsuppliers should also be included to link the elementsof the enterprise. Distribution means that the systemaids in accessing different activities in the shipyard.As a result, workflow and scheduling can be adjusted.

Another strategy is to devise a performancemeasurement control system to track and controlprogress, thereby measuring activities that affectmanufacturing (e.g., internal customer/supplierrelationships; external customer/supplierrelationships; Pareto charts; SPC charts). A trackingsystem also needs to provide control mechanismswhich maintain progress and provide insight topotential problems through leading indicators, and aclosed-loop feedback system to enable correctiveactions.

Statusing

INTRODUCTION:Statusing refers to the timely and comprehensive

measuring of a progress, independent of calculatinginput or observing variances. This operation involvesperiodic reviews of a process (e.g., material handling,monitoring, tracking) in terms of its current state/condition and the efficiency of its cost factors duringexecution. From this data, facilities can explorepossible corrective actions to improve their processes.

STATE OF THE INDUSTRY:Statusing involves reviewing a project’s progress

based on an array of parameters. These parametersmay include schedule performance, cost performance,cost statusing, resource statusing, and statusing byvariables (e.g., weight, noise). Based on surveys,department managers determine the parameters oftheir projects’ progress, and then discuss thesefindings at status meetings. Although cumbersomeor repetitive at times, statusing can be very insightfuland efficient because of the quick interaction amongthe participants. Additionally, the effectiveness of theprocess is dependent on the knowledgeability of theparticipants.

STATE OF THE ART:Successful organizations use computerized systems

which provide information that is timely andsynthesized to a minimal number of key businessmetrics. The most advanced systems will displaylower level data that focuses on the business metriccorresponding to under performance.


is underway.

ENABLING TECHNOLOGIES:Enterprise-wide management systems are one of

today’s most effective status-providing tools for upperand middle management. These systems provide statusinformation via databases that are accessible througheither the Internet or the Intranet.

MANUFACTURING STRATEGIES:A novel approach for statusing is the use of a

common communications framework such as theInternet or the Intranet. A company creates a link,known as a project team status wall, to its existingwebsite. Only the project’s members have access to

13

the overall group’s area. Members can log onto thesite and input the status reports pertaining to theirtasks. Members also have write/read access to theirown tasks, but read-only access to everyone else’s.This approach of centralizing data reduces time,effort, and costs associated with traditional methods(e.g., arranging meetings, contacting projectmembers). Statusing via a common communicationsframework provides time-to-time updated reportsfrom any location at any given instant.

Steel Outfitting ManufacturingAssembly

Beveling

INTRODUCTION:Beveling is the process of preparing the edges of

production piece parts (e.g., plates, shapes) for weldingto other parts. This process involves cutting, milling,or grinding the part’s edges to an angle (excludingnormal or square to the part) most conducive toefficient welding. Beveling is often a secondaryoperation whereby a part is fabricated with square-cut edges and then later beveled. Bevel geometry isdetermined by the weld joint design/geometry, partthickness, and planned welding process and position.The geometry can also include single-side, knife-edged bevels (top or bottom edges); single-side bevelswith a nose; double bevels (top and bottom edges);bevels with chamfers; J bevels; and U bevels.

STATE OF THE INDUSTRY:State of the industry for beveling plate and profile

parts will be described separately. The variousprocesses for beveling plate parts by shipbuilders willbe described first:

• Numerical control (NC) contour beveling isperformed by an NC burning machine equippedwith a cutting torch, whose bevel angle iscontrolled by the NC data and varied in real timeas the part is cut. This method allows multiplebevels with different geometry and changinginclines to be cut in an automated manner duringthe plate part’s primary fabrication operation.Plasma arc cutting is the cutting process mostcommonly used. NC contour beveling is generallylimited to single-sided, knife-edged bevels. Doublebevels and bevels with noses can be cut, providedthe parts are bridged or stitched together toprevent movement of the parts between the initialand subsequent torch passes.

• Triple torch NC beveling is performed by an NCmachine equipped with three torches mounted ona single tool carriage. One torch remains verticalto perform a square cut, while the other twotorches can be adjusted to cut bevels of varyingangles and directions. Torch adjustment is manualand remains constant while the torch is moving.If the bevel geometry changes, the cut must bepaused and the torch angles manually adjusted.Oxy-fuel burning is the cutting process used, andthe bevels are cut during the part’s primaryfabrication operation. Although slower than CNcontour beveling, triple torch burning is muchmore versatile and can cut single bevels with anose; single bevels with a nose and a chamfer; anddouble bevels all in a single pass.

• Mechanized beveling is performed by mechanizedtorch carriages which run on tracks installedparallel to the cut to be beveled. This method isalso a secondary operation. After a plate part isNC cut with square edges, it is moved to anotherwork station where a track is installed, a carriageset-up, and the torch(es) are manually adjustedto provide the desired bevel geometry. An operatormonitors the job and adjusts the torches asneeded. Oxy-fuel burning is the cutting processused.

• NC milling is used in limited specializedapplications such as preparing plates for one-sided welding. Milling is limited to straight paralleledges, but can perform a variety of complex edgepreparations including double bevels, bevels withchamfers, J bevels, and U bevels. Milled edges areextremely accurate with sub-millimeter tolerances.

In beveling other ship production material, theprocesses are similar. Profile beveling (or bevelingstructural shapes that include tees, angles, channels,or flat bars) is being performed using robotictechnology. Automated profile beveling is performedduring the primary cutting operation using robotsequipped with either oxy-fuel or plasma cuttingtechniques. Manually cut profiles are beveled usingmechanized equipment, if the profiles are large enough,and with hand torches (oxy-fuel), if not. Some smallprofiles are beveled manually using hand-held grindersas a secondary operation, either in the shop or in thefield.

STATE OF THE ART:The current state of the industry in beveling is near

the state of the art. Advanced cutting methods suchas waterjet cutting, high definition plasma cutting,

14

and laser cutting could be utilized in primary andpossibly secondary beveling operations; however,capital costs for these methods are high as specializedequipment and training is required. In addition, thesemethods are shop operations so they would beunsuitable for filed applications. But despite the cost,these new beveling processes greatly improve accuracy.In cases where tolerances are not critical, theassemblies can be processed using traditional bevelingmethods.

STATE OF RELATED INDUSTRY:The state of related industry is the same as the state

of the art for beveling.

ENABLING TECHNOLOGIES:NC contour beveling requires a means to embed the

beveling data into the NC cutting data. Generally,bevel data is developed in the electronic design orproduct model based on the weld joint’s design andphysical geometry. The bevel data would then beextracted with the NC contour for nesting and burning.

MANUFACTURING STRATEGIES:A key strategy for efficient beveling is to cut neat

parts that are beveled during the initial fabricationprocess. This approach allows bevels to be cut withefficient mechanized or automated equipment, andprovides a more accurate, higher quality cut at alower cost than beveling at fit-up on a platen or a ship.

Cutting

INTRODUCTION:Cutting is the process by which structural and

outfitting piece parts are fabricated from their rawstock material. Structural steel is generally cut usinga thermal cutting process such as oxy-fuel flame,plasma arc, or laser beam cutting. For plasma andoxy-fuel cutting, the torch is moved along the cutpath by a variety of means including manually (handtorch), mechanized equipment, numerical controlmachines, and robotics.

STATE OF THE INDUSTRY:State of the industry for cutting plate and profile

parts will be described separately. The variousprocesses for cutting plate parts by shipbuilders willbe described first:

• NC cutting of plate parts is by far the predominateprocess used by shipbuilders. Both plasma arcand oxy-fuel processes can be used depending onplate thickness. Generally, plates less than one-

inch thick are cut using plasma arc because of itshigher cutting speeds and superior edge quality.NC cutting produces the most accurate parts atthe highest levels of productivity. NC cut partscan be cut square to be beveled later, or beveledusing triple torch oxy-fuel or contour bevel plasmaarc cutting technology (Figure 2-2).

• Mechanized cutting, in the shop, is generally limitedto rectangular parts. Gantry mounted mechanizedmachines equipped with multiple torches are usedto strip plates into rectangular parts with paralleledges. Oxy-fuel is the most common process usedon mechanized machines. These machines canproduce square and beveled cuts. Torch separation(part width) can be set manually or dialed-in onmore modern machines. Mechanized cutting isalso used for trimming parts after shaping when ascribe line is applied from a mold; a track is set upparallel to the scribed edge; and an operator manuallyadjusts a torch carried by a mechanized carriage asit moves down the track. Mechanized cutting withtracked carriages is commonly used for makingcuts in the field.

• Optical follower cutting equipment is still used forfabricating small parts. An optical follower utilizesa sensor that follows the contours of a full-sizedrawing of the part. One or more torches thenrepeat the path of the optical follower to producesingle or multiple copies of the part. Either plasmaarc or oxy-fuel process can be used. The parts aregenerally square cut.

• Hand torch burning is rarely used to fabricate(cut) plate parts in the shop. Hand torch burning,both plasma arc and oxy-fuel, are commonly usedfor a broad range of cutting activities in the field.

Figure 2-2. 30-Foot Burning Machine

15

Profile cutting is performed by automated roboticcutting lines or manually with hand torches. Roboticprofile cutting is more accurate and productive thanmanual cutting, and can feature both plasma arc andoxy-fuel processes for beveled or square cuts. Manualcutting of profile parts is still the predominate methodof cutting profile parts in many shipyards. The oxy-fuel process is generally used. This method requiresthe parts to be laid-out (or measured) with the end-cut features drawn on the part prior to cutting.Manual cuts usually require grinding to achieve therequisite cut quality.

STATE OF THE ART:NC cutting is the preferred method of delivering

state-of-the-art cutting processes. Advances in cuttingtechnology are primarily in the cutting processes.The state of the art is advancing by making the faster,higher quality, more accurate cutting processes suchas laser, waterjet, and high-definition plasmaapplicable to thicker material. Laser cutting isgenerally accepted as the most accurate, highest cutquality cutting process. In years past, laser cuttingwas limited to sheet metal. Current laser technologyis capable of cutting material up to 30-mm thick. Newdevelopments promise even greater capabilities atlower capital investments, making laser cutting amore attractive option for shipbuilders.

Waterjet cutting can leave irregular kerfs whenspeeds and thickness are increased. This situationcan be avoided by reducing the speed of the cut;however, production rates will be drastically reduced.Waterjet machines are typically stationary, and canrequire high maintenance.

Cutting tools must have high hardness and stiffnessto resist deformation under the high cutting forcesexerted in machining operations. These tools mustalso be high-wear resistant to maintain sharp cuttingedges and permit high machining accuracy overextended periods of time. Laminated ceramic compositecutting tools have been developed which demonstrateimprovements in strength, toughness, and thermalshock resistance compared to conventional, non-laminated ceramic composites.

STATE OF RELATED INDUSTRY:Related heavy manufacturing industries (e.g., farm

and construction equipment) have embraced lasercutting technologies, and are working to take fulladvantage of their improved accuracy to reducedownstream fitting and welding costs. These industriesare also moving toward fully automated NC cutting

cells which can load raw stock, execute cuttingprograms, and off-load the finished parts and scrapwithout human intervention. These cells promisearound-the-clock, unmanned operation, therebyfurther reducing the cost of production.

ENABLING TECHNOLOGIES:Computer numerical control (CNC) and direct

numerical control (DNC) automated cutting stationsprovide the highest accuracy, quality, andproductivity. While there are many differentgenerations of equipment in use, the most moderncutting stations provide enhanced accuracy andcontrol including self-diagnostics. Automated cuttingdepends on the availability of NC cutting data thatcan be developed using a variety of computer aideddesign/computer aided manufacturing (CAM) tools.In addition, continuing advances in laser technologymay result in the cutting of thicker materials in thenear future.

MANUFACTURING STRATEGIES:The process of delivering, loading, and unloading

material to different cutting stations requires a greatdeal of coordination, particularly when a wide rangeof plate sizes and thicknesses exist. To minimize theamount of labor spent on these non-value addedactivities, many shipyards are combining theadvantages of continuous flow manufacturing (CFM)and JIT manufacturing. By successfully controllingthe planned flow and manufacture of materials asthey move through the cutting process, these strategiespromise to eliminate multiple handling and storage ofparts cut in advance of their need.

Forming

INTRODUCTION:There are two types of forming processes: hot and

cold. Both are regarded as expensive and cumbersomemanufacturing processes which rely on a combinationof manual and semi-automatic operations. For hotforming, each part made requires a set of forming dies(male/female) that represent a part and itsconfiguration. To form the part, the materialundergoes a series of heating and pressing operationsuntil the final shape is achieved. If the material ismanipulated outside its temperature parameters, thenits properties will be altered and the material willhave to be replaced or annealed/tempered. For coldforming, the operation excludes the heating step.

16

STATE OF THE INDUSTRY:In searching for a more economical and faster way

to produce these parts, shipyards developed coldforming techniques using existing equipment. Inaddition, multi-functional dies can readily be madein-house at a fraction of the cost of hot forming dies.The female die is used for a wide range of part sizes,and the male die is used for parts within a specificrange of radii. To manufacture a part, the pressoperator gradually rotates and presses the materialuntil the desired shape is achieved. Validating theaccuracy of these shapes is confirmed using radiusgauges, hand sweeps, or molds. The scale of certainitems undergoing cold forming often relies on moreadvanced accuracy control using photogrammetryand laser-coupled theodolites. Although some partsmust be produced through hot forming techniques,companies can expand their capabilities by developingcold forming techniques. This approach enablescompanies to perform in-house manufacturing, reduceoutsourcing, decrease production costs, and improvequality.

The size and thickness of the material beingprocessed limits typical shipyard forming capabilities.Components that require close tolerances use CNCpress or rolling machines (Figure 2-3), which oftenfeature the mechanical means to position and formthe material. Unlike forming thin sheet-metal materialsas used by automotive and air-frame industries,forming thick section large components requireslarger, less accurate machines. The ability to achieveand maintain high levels of accuracy translates intorepetitive operations and greater downstream costswhen straightening distortion becomes necessary. Iftolerances are not critical, thicker material sectionscan be processed using the traditionally older formingequipment found at shipyards.


is underway.


is underway.

ENABLING TECHNOLOGIES:As a primary operation, forming has changed very

little, largely due to the low volume production ofrelatively subtle compound shapes found inshipbuilding. Newer CNC equipment capable ofproviding greater precision and dimensional control

are available in the market place and, when coupledto product model electronic data, can replicate exactsurface development required by ship designers.

The ability to accurately measure and determinethe fairness of rolled or formed shapes has beenenhanced by modern industrial measurementtechniques. Using theodolites, coordinate measuringmachines, and other similar devices, shipbuilders cannow determine and validate the consistency of formedparts. These capabilities did not previously existacross the industry.

MANUFACTURING STRATEGIES:For the shipbuilding community, forming operations

occur shipboard as well as in the supportingmanufacturing shops. Although strategies may differ,the principle objective is aimed at defining similarwork content that is compatible with productioncapacity. Another factor is the ability to maintain acertain range of flexible manufacturing, while stillarranging production equipment into manufacturingcells to support the principle of continuous flow.Rather than cluster similar operations in specificareas, the arrangement of the equipment should bedictated by the work content and the operationsneeded to produce a family of parts. This approachwould maximize production capacity.

Punching and Drilling

INTRODUCTION:Punching and drilling are similar production

processes that create holes in substances by usingequipment to remove excess material. Punching usesforceful, repeated blows to pierce through the material,

Figure 2-3. Rolling Machine

17

while drilling uses cutting bits to bore through thematerial. Piece part fabrication relies on theseprocesses to provide certain design details whichcannot be executed by other means.

STATE OF THE INDUSTRY:Punching and drilling operations trace back to

traditional drop forging, where brute force molded,shaped, and pierced the materials designed to bejoined with others. The precision and accuracy ofsuch operations often had significant, unacceptablevariability. Modern shipbuilding has witnessedsignificant changes in the ability to accurately processmaterial in production. As ship designs became morecomplex, the accuracy in piece part fabrication becamemore important. This event lead to correspondingchanges in the functionality and accuracy ofproduction equipment for punching and drilling. Theimportance of controlling the position, location, size,and quality of edge cut when manufacturing piecepart for steel, sheet-metal, or piping becomes criticalto downstream assembly operations, if cost is to becontrolled. Today, many shipbuilders maintain oneor more drilling and punching machines. Many of thelarge capacity machines (Figure 2-4) are older and,therefore, lack any sophisticated control. There isevidence that many yards are using CNC punchingmachines as well as milling machines in production.

STATE OF THE ART:The size and thickness of the material being

processed limits typical shipyard drilling andpunching. Components that require close toleranceswould utilize CNC punch presses that have mechanical

means to position the plate. The punching action canproduce holes or shapes with greater accuracy. Iftolerances are not critical and holes have largediameters, CNC burn tables can be used. The burntables also allow for thicker material sections to beprocessed. While drilling is not typically performedon many of the parts used in ship manufacturing,standard method such as CNC machining centers,drill presses, and radial arm drills can be used.

Although these processes have not undergone anyrevolutionary changes, there have been manyadvancements in the materials and consumables thatperform these functions. Today’s drill bits featurecoatings which increase their tool life and producemore accurate features. These bits also have beenported for high-pressure coolant, which allows forchip removal from the cutting face. This methodprovides greater feed rates while drilling, therebyincreasing production. The quick-change carbideinsert bits also allow for fast and easy replacement.Punching equipment has significantly reduced in sizewithout sacrificing capacity. Inexpensive units canbe placed throughout manufacturing facilities toexpedite the punching process for small features andindividual manufacturing requirements.

STATE OF RELATED INDUSTRY:The state of related industries is the same as the

state of the art in punching and drilling.

ENABLING TECHNOLOGIES:As secondary operations, punching and drilling

have undergone a significant transformation. Theremoval of material to create accurate and preciseholes is being performed in a variety of ways inmodern shipbuilding. CNC plasma arc, oxy-fuel, laser,and waterjet cutting are current processes usedwithin the industry to cut holes. Portable and radial-arm drilling machines are still used with less accuracy,as are manual hydraulic punches along with plasmaand oxy-fuel cutting machines. CNC boring andmilling machines, prevalent in most modern machineshops, provide the ability to produce piece parts withgreat accuracy.

MANUFACTURING STRATEGIES:For the shipbuilding community, punching and

drilling operations occur shipboard as well as in thesupporting manufacturing shops. Although strategiesmay differ, the principle objective is aimed at definingsimilar work content that is compatible withproduction capacity. Another factor is the ability to

Figure 2-4. Drilling Asset

18

maintain a certain range of flexible manufacturing,while still arranging production equipment intomanufacturing cells to support the principle ofcontinuous flow. Rather than cluster similaroperations in specific areas, the arrangement of theequipment should be dictated by the work contentand the operations needed to produce a family ofparts. This approach would maximize productioncapacity.

Shaping

INTRODUCTION:Shaping is a process that affects a variety of

material types and manufacturing operations.Essentially, shaping involves production processesthat enable the shipbuilder to create complex three-dimensional surfaces, generally from flat stockmaterial. Additionally, shaping refers to the contouringof flat stock material into irregular geometric shapes.Piece part fabrication relies on shaping processessuch as pressing, rolling, line heating, and foldingmachines to provide certain design details that cannotbe executed by other means.

STATE OF THE INDUSTRY:Shaping relies on a variety of process equipment to

achieve design requirements that meet ship specificneeds. Like punching, the precision and accuracy ofshaping operations often had far greater variabilitythan what was acceptable. Modern shipbuilding haswitnessed significant changes in the ability toaccurately process material in production. Theimportance of controlling the position, orientation,location, size, and finish quality of shaped parts whenmanufacturing piece part for steel, sheet-metal, orpiping becomes critical to downstream assemblyoperations, if cost is to be controlled.


is underway.


is underway.

ENABLING TECHNOLOGIES:Utilized as either a primary or secondary process,

shaping operations have undergone a significanttransformation. Developing 3-D shapes of materialgenerally engages several steps to achieve a finalproduct. As a result, shaping is both art and science,

where science may provide only part of the solution.The scale of piece part undergoing this process dictatesthe degree of accuracy achieved. Controlling theprocess to ensure the best results relies heavily onaccuracy control and measurement equipment.Whether bumping material on a manually operatedpress or roll forming larger flat stock into compoundshapes, control is critical for cost efficiency. Alternatemethods, such as line heating which involves localizedthermo forming to achieve shape in small and largeparts, tend to add excessive cost to the overall processparticularly when employed as a distortion controlmeasure.

MANUFACTURING STRATEGIES:For the shipbuilding community, shaping operations

occur shipboard as well as in the supportingmanufacturing shops. Like other manufacturingoperations, shaping will continue to be part of theoverall ship production process. However, minimizingcomplex parts in ship designs ultimately reduces thevariability and cost associated with this process.Applying the principles of Design for Manufacturingand Assembly (DFMA) is crucial to better manage thecost of unique low volume parts. Pressing and formingmaterials, where material is displaced beyond itsyield point, achieve more consistent and predictableshapes than thermal forming processes.

Heating

INTRODUCTION:Heating is a secondary process traditionally

reserved for material items that will undergo formingand straightening operations. The practice of heatingmaterials to enable improved forming is more an artthan science. During the past 20 years, modernshipbuilding has introduced new generations ofmaterials that differ somewhat from conventionalmild carbon steels. As a result, different constructiontechniques, such as heating, have been developed toproduce the compound shapes and forms required bythe designer. The introduction of higher strengthsteels (e.g., AH, DH) and alloys (e.g., High StrengthLow Alloy [HSLA]; High Yield [HY] 80 and 100 ksisteels) for specific applications in shipbuilding hasexacted the need to master how and when heating canbe an effective process to employ. Shaping, forming,pressing, and welding these materials often relies onheating processes or hot work to achieve desiredcontours and compound shapes, or to straightendistorted members. One process, line heating, usesacetylene torches and a series of pattern zones to

19

produce complex parts with relative ease and efficiency.This method is found in commercial overseasshipbuilding, where mechanics knowledgeable in howto control the surface development of a part usingheat are particularly revered.

STATE OF THE INDUSTRY:Heating, as a process in manufacturing, is generally

considered an integral, secondary operation. As ameans of controlling either mechanical or welddistortion, heating is commonly used during theassembly phase of construction. Unfortunately,controlling distortion at this point adds considerrework and often repair to surrounding areas thathave been painted or insulated. Ideally, the process ofheating to correct for excessive deflection should beavoided through process and accuracy controltechniques. Within manufacturing, heating may bethe process of choice during small part fabrication toenhance forming operations. Heating may also benecessary to reduce residual stresses in raw stock aswell as material items that have already undergonesome manufacturing. To accomplish this, there are avariety of techniques available including free-formingusing hand torches, larger ovens, furnaces, orautoclaves.

The ability to monitor the degree of forming orshaping material using heating as the process oftenrequires hand scribes. These scribes (or pantographs)are capable of tracing a series of grided patternsuniformly across compound surfaces. As the heatingprocess continues to change the shape of the item,mechanics check and recheck the accuracy of theirwork. Unfortunately, this process is virtually allmanual, and relies on a few skilled tradespeopleknowledgeable in controlling the results of heatforming. Unless the need for absolute precision ariseswhich would require expensive CNC equipment andscarce skilled fabricators, line heating will continueto be a special process step in shipbuilding. Theability to achieve and maintain high levels of accuracytranslates into repetitive operations and greaterdownstream costs when straightening distortionbecomes necessary. If tolerances are not critical,thicker material sections can be processed using thetraditionally older forming equipment found atshipyards.

STATE OF THE ART:Line heating remains the state-of-the-art method

for shaping plate material. The advent of new steels,such as the HSLA-65, has recently spurred

investigators to examine the parameters used for lineheating these materials. State-of-the-art analysistechniques make it possible to predict and adjust theheating parameters to control the amount of distortionand residual stress development in the assembly. Lowheat input welding techniques are gaining acceptanceas a viable method for controlling distortion in shipassemblies. Analysis techniques are also capable ofprediction the distortion associated with welding so,whenever practical, the distortions may be controlledduring fabrication. Induction heating (as opposed toresistance heating) holds great potential for heatingmaterial in a shipyard environment such as preheatfor welding. This process potentially can reduceheating power consumption, after a significant initialcapital investment.


of the art in heating.

ENABLING TECHNOLOGIES:As a primary operation, heating has changed very

little largely due to the low volume production ofrelatively subtle compound shapes found inshipbuilding. Whether to relieve stresses, improveworkability, or coax a form from a flat material,heating remains relatively nondescript in the overallshipbuilding process. While improvements inmonitoring fixed ovens enable operators to controlheat ranges with greater precision, there are noknown technologies that can replace the skill ofveteran shipbuilders capable of sculpting complexshapes from flat materials using simple hand torches.

MANUFACTURING STRATEGIES:For the shipbuilding community, heating processes

occur in the manufacturing and assembly operations.Although strategies may differ, the principle strategyaims at defining and selecting the most appropriateapplication and circumstance to introduce heating asthe process of choice.

Shearing

INTRODUCTION:Shearing is a more traditional process, often reserved

for less complex materials where accuracy is not asignificant requirement. The process involves thesizing of specific manufactured part dimensions byusing powered hydraulic machines. These machinestear the base material along a single axis much like

20

scissors cutting paper. Typically, shears are manuallyoperated while the material is positioned and heldduring the shearing process. Part candidates aregenerally flat sheet stock, ferrous and non-ferrousmaterials ranging in thickness from light gauge sheetmetal to thicker steels approaching 0.75 inch.Depending on the thickness of material, the resultingfinished items exhibit non-uniform dimension duelargely to the mechanical tearing along one or moreedges. This edge tearing results in minor damage tothe mechanical properties of the base material and, insome cases, diminishes the quality necessary forwelding.

STATE OF THE INDUSTRY:Because the shipbuilding industry produces large

volumes of steel, some of which are used as consumablematerial, the process of shearing is common.Regardless of the production volume, shearing providesa relatively fast and economical option whenmanufacturing small, simple, flat parts. Materialitems (e.g., welding clips, backing bars, gusset plates)must be produced in relatively high volume to supportsteel assembly and erection. The need to produce suchmaterials has been satisfied using shears as oneoption. To manufacture a part, the operator positionsmaterial into the throat of the shearing machinebetween the stationary and shearing surfaces;energizes the shearing cycle; and begins to cut thedesired material lengths using a temporary stop orreference point usually located on the machine. Shears,like presses, have inherently similar mechanics andcan present certain dangers to the operator. The forceand speed of operation is generally a function of theshearing tonnage, which is typically lower than highcapacity presses found in shipbuilding.

The ability to achieve and maintain high levels ofaccuracy translates into less downstream costs whenstraightening distortion becomes necessary. Iftolerances are not critical, thicker material sectionscan be processed using the traditionally older formingequipment found at shipyards.


is underway.


is underway.

ENABLING TECHNOLOGIES:As a primary operation, shearing has changed very

little largely due to the low volume production ofrelatively simple items such as welding clips, jacks,and other small consumable products typically foundin shipbuilding. The introduction of higher speed andmore accurate equipment, capable of providing greaterprecision and dimensional control, are available inthe market place. When coupled to product modelelectronic data, these kinds of manufacturingmachines can replicate exact surface developmentrequired by ship designers.

MANUFACTURING STRATEGIES:For the shipbuilding community, shearing

operations are located predominately inmanufacturing shops. Although strategies may differ,the principle objective is aimed at defining similarwork content that is compatible with productioncapacity. Another factor is the ability to maintain acertain range of flexible manufacturing, while stillarranging production equipment into manufacturingcells to support the principle of continuous flow.Rather than cluster similar operations in specificareas, the arrangement of the equipment should bedictated by the work content and the operationsneeded to produce a family of parts. This approachwould maximize production capacity.

Sawing

INTRODUCTION:Sawing is a manufacturing process where material

is cut into specific sizes using abrasive cuttingmethods. A variety of material types can be cut usingdifferent configurations of semi-automated saws andmanual saws (e.g., hacksaw). Electrically poweredsaws range in size, power, throat depth, and orientation(either vertical band saws or horizontal saws). Utilizedas either a primary or secondary process, sawing isgenerally reserved for the fabrication of smaller pieceparts where speed and accuracy are less important.

STATE OF THE INDUSTRY:Sawing has been a traditional process that is

applied to a wide range of materials including steel,sheet metal, cabling, insulation, pipe, and othermiscellaneous materials. Because sawing relies onabrasive material removal, different configurationsof materials and density of cutting teeth have beendeveloped to cut materials more efficiently. Certainmodel saws feature self-lubricating systems that

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improve cutting speeds and reduce abrasive wear andheat. Consumption and repair of abrasive cuttingblades, however, tend to influence the economy andaccuracy of cutting certain materials.

Within the shipbuilding industry, band andhorizontal saws are used for cutting materials thatare hand loaded and unloaded. Sawing almost alwaysrelies heavily on operator intervention to control andmonitor the process. The process lacks the necessarysophistication to permit multiple position cuttingwithout intervention. Coupled with consumables andlimited controls, sawing is the least desirable processfor fabricating material, particularly when speed andaccuracy are important. More efficient cuttingequipment and methods have been developed,specifically for the larger flat stock material that hasdiminished the need for conventional sawing.

STATE OF THE ART:Sawing is typically used for sectioning items such

as bar stock and rod. Most saws used in shipyards areinexpensive; designed for quick and rough cutting;and would be used where thermal cutting is notrecommended or possible. In addition, parts to bemachined could require saw cuts to eliminate anyhardened surfaces.

Today’s state-of-the-art saws have greater capacityand are able to handle much larger components.Automatic feeders can be utilized to maximizerepetitious production cutting, thereby increasingthroughput. In addition, new materials andconfigurations of the cutting blades increase feedrates which, in turn, increases production.


of the art in sawing.

ENABLING TECHNOLOGIES:Utilized as either a primary or secondary process,

sawing operations have changed little over the past.Do-All and Marvel saws continue their domination inthe marketplace; however, some suppliers haveintegrated additional operations into a sawing workcenter to complement typical fabrication steps forparticular times. Geka, for example, has combinednotching and coping along with hole punching andsawing operations into one single ironworker. Forthe most part, vertical and horizontal band sawspredominate. While limited controls are available toimprove performance, most sawing machines continueto be manual. In addition, certain raw stock materialitems will continue to create a need for these machines.

MANUFACTURING STRATEGIES:Due to the limited need for conventional sawing

equipment, there is little evidence that anymanufacturing strategy applies. As with other processequipment, similar operations have traditionally beencloistered together without regard to work content ormaterial flow. However, minimizing complex parts inship designs will ultimately reduce the variability andcost associated with this process.

Disposing

INTRODUCTION:Disposing involves the storage, handling, and

containment control of a wide range of byproducts(solids, liquids, gases) produced during shipbuildingoperations. The managing of this wastestream is anintegral part of the shipbuilding industry’sresponsibility. Proper waste management involvesmany aspects such as identifying safeguards; reducinghazardous exposure; and complying withenvironmental laws and regulations.

STATE OF THE INDUSTRY:To ensure proper waste management, an internal

team of experts determines the risk, liability, expectedcost, and developing viable strategies. This team canalso identify and implement waste managementprograms that minimize environmental exposure andproduce the best payback. Conventional practiceshave included the use of valuable land sites to eitherdump waste or engage in the practice of sorting andseparating different materials. The wide array ofshipbuilding byproducts can range from relativelyharmless scrap metal to hazardous materials likenuclear waste. Disposal technologies consist largelyof dedicated areas where materials can be loaded fortransfer to other disposal sites as recognized andcontrolled by local or regional governments. Reducingthe risk and liability associated with the disposing ofhazardous and non-hazardous materials have becomeimportant goals at many facilities.

STATE OF THE ART:Disposal of metals is no longer considered a suitable

method of dealing with excess or scrap metal. Allexcess metals are now recycled. Likewise, solventsand oils can no longer be land filled. Solvents and oilsare usually fuel blended and burned for their BTUvalue. However, the best methods for dealing withsolvents and oils is to recycle the materials or substituteless hazards materials in their place.

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of the art in disposal.

ENABLING TECHNOLOGIES:Developing and analyzing a best practice to

support waste disposal may not necessarily pointtoward a technological solution without anextremely detailed business case. For example,outsourcing waste hauling may prove to beconsiderably more attractive financially thancontinuing hauling waste using internal resources.Identifying and addressing the surrounding issuesmust be undertaken to determine the type of serviceneeded; the type of hauling equipment required;the availability and cost of local/regional haulingand disposal; and the availability of licensedoperators to perform this work. Depending on thesituation, the method of payment will either bebased by the ton or by a volume measure. In eachcase, the short and long term economic factorsmust be evaluated. Methods of payment for disposalcan also offer opportunities for cost improvements.

MANUFACTURING STRATEGIES:Managing the wastestream to ensure compliance

with state and federal laws as enforced throughregulatory bodies is the only viable operatingstrategy. Understanding the mitigatingcircumstances and the requirements necessary toenact policies and procedures that meetinterpretation of the law must rely on excellentcommunication. Establishing and maintaining goodcommunication among the shipbuilding communityand between the organizational structure of eachshipyard is critical to avoiding penalties andpotential shutdowns.

Recycling

INTRODUCTION:Recycling involves the storage, handling,

containment, and reuse of materials that are part ofthe shipbuilding wastestream. Complying with localand regional regulations as well as the challenge ofconverting this portion of the industrial wastestreaminto revenue are integral parts of the shipbuildingprocess.

STATE OF THE INDUSTRY:As a maritime industry, shipbuilding has generally

been more conscientious about solid waste disposal

and recycling than many industries. Effective recyclingrequires a thorough understanding of the wastestreamand waste management activities of any organization.In many cases, recycling mandates can be met costeffectively. However, organizations should beencouraged to recycle for environmentally consciousreasons. This focus will provide intrinsic value to thecommunity and, in return, the organization willstrengthen its community relations.

Issues to consider in the analysis of potentialrecycling programs include:

• Overcoming negative positions in theorganization.

• Understanding how waste is generated.• Understanding how waste is collected and

disposed.• Identifying opportunities to recycle materials

within the current collection and disposal system,piggy backing where possible.

• Developing new recycling programs that minimizethe impact on normal operations. For example,recycling separation at the source is generallythe cheapest way to begin the recycling process.

• Developing and sustaining markets for recycledmaterials. Organizations should expect volatilityrelative to material outlets and prices.

In shipbuilding like other heavy industries, there isa considerable investment in materials. Many itemsare recyclable if provisions for handling and disposingof the material are considered when a process isoriginally established.

STATE OF THE ART:The process of recycling metal is necessary because

waste material results as a bi-product of machiningand cutting operations. All excess metal is collectedand sent to a recycler for processing and reuse.Ideally, the use of near-net shape parts would reducethe volume of metal needing to be recycled.Unfortunately, this is not always possible andrecycling of the excess metal becomes necessary.Recycling of solvents and oils involves collecting thespent material and processing by various means forreuse. Some solvents and oils cannot be recycled,therefore disposal becomes the only available option.


of the art in recycling.

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ENABLING TECHNOLOGIES:Establishing organizational task teams to prevent

and control pollution is an important first steptoward increasing the volume of recyclable products.The technologies are unsophisticated for the mostpart, and range from paper shredders to filtrationsystems to asphalt, glass, and scrap steel recycling.For example, one shipyard recycled over 7,000 tons ofasphalt within a five-year period, and another atmore than 4,000 tons of paper and 1,800 tons ofcardboard. A drum crushing facility has de-headedand crushed over 70,000 55-gallon drums. In theseexamples, the facilities were able to eliminated thehauling and disposal fees collected by local landfills.

The process of recycling metal is unsophisticated atthe present time. Excess metal is collected and sent toa recycler for remelting. The use of near-net shapeparts is one of the best ways to reduce the volume ofmetal needing to be recycled. Since this is not alwaysfeasible with large castings and plates, recyclingbecomes the only method available. Recycling ofsolvents and oils can be reduced by substitutingexisting chemicals with less hazardous products.Many companies exist which specialize in findingsafer chemical substitutes that have the sameperformance characteristics as the material beingreplaced.

MANUFACTURING STRATEGIES:An important first step in developing a long term

strategy is to establish an organizational team witha vested interest in waste management includingwaste generation, collection, disposal, and recovery.Managing the process, as well as communicating theimportance of proper disposal and recycling, are alsofundamentally important to the success of a program.

Inspecting

INTRODUCTION:Inspection within the shipbuilding industry

represents one process with many facades. Whetherit involves material receipt or ship system completion,inspection remains an iterative process that requiressophisticated practices similar to those in otherindustries. Inspection within the shipbuilding industrycan also involve highly specialized advancedtechnologies and services, especially in such areas asmanufacturing, assembly processes, and sea trials.In addition, the process of inspecting productionmaterial can involve aggressive measures to validatethe pedigree of material as well as certifying thefunctionality or operability of particular ship system

equipment. Inspecting dimensional characteristics ofboth small and large components and assembliestypically involves highly accurate measurementmachines that can efficiently compare as-built to as-designed.

STATE OF THE INDUSTRY:Whether shipbuilding involves military combatants

or commercial class designs, inspection plays a vitalrole in the validation process for both owner andbuilder. Beginning with material receipt, conventionalmeans to verify quantity, size, material type, potentialdamage, documentation, warranty, demurrage, andcompleteness are evident. The inspecting process canbe more rigorous when verifying dimensions. Use ofcoordinate measuring machines is common withinthe industry. There are also other technologies suchas spectroscopy, ultra sound, x-rays, and magneticresonance that ensure the quality and consistency ofmaterials which safeguard the health and safety ofthe shipbuilder and shipowner. Material Data Sheetsare typically used in the receipt inspection functionwhen consumable materials such as solvents, cleaners,and paints are involved.

STATE OF THE ART:While non-destructive evaluation (NDE) plays a

vital role in shipbuilding validation, it is generallyassociated with the examination of weldments forassembly soundness. Recently, ultrasonic inspectionhas gained acceptance as an alternative to radiographyfor volumetric inspection of material. New time-of-flight ultrasonic techniques hold great potential fortruly sizing the through thickness dimension ofinternal discontinuities, and new ultrasonic recordkeeping systems provide the necessary auditdocumentation. Advanced systems such as digitalphotogrammetry, laser coupled theodolites,interferometers, and 3-D laser scanners have greatlyimproved the accuracy and efficiency of the inspectionof complex objects, up to and including entire shiphulls. In the near future, incremental improvementsof these systems are anticipated. These digitalmeasurement systems have enabled near real-timefeedback to Computer Aided Design/Computer AidedManufacturing (CAD/CAM) analysts so thatcomponent designs and as-built conditions can becompared, archived, and updated as necessary.

STATE OF RELATED INDUSTRY:The state of the related industry is the same as the

state of the art in inspecting.

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ENABLING TECHNOLOGIES:The inspection process for manufacturing activities

is as varied as the broad range of products andoperations that define manufacturing. Dimensionalaccuracy of components remains, however, one of themore important attributes of the ship assemblyprocess. Validating, verifying, recording, andcomparing dimensional data that defines the toleranceboundaries for an extensive scope of products is acritical shipbuilding requirement. Innovativetechnologies (e.g., digital photogrammetry, lasercoupled theodolites, interferometers, 3-D laserscanners) enable inspectors to efficiently inspectrelatively complex objects with accuracy well beyondwhat was possible only five years ago. The ability toimport digital design data and compare as-built or as-delivered product dimensions allows analysts todetermine potential changes to the form, fit, orfunction of any given component.

As for the documentational side of inspecting,digital records are now archived and transmittedvia computer terminals, thereby displacing theburdensome, paper-based records that usuallyrequired large storage areas. The ability tocommunicate inspection information in a timelymanner has also improved. Widespread use ofelectronic mail via Internet, Intranet, fax machines,and other office services can transmit data tomultiple viewers quickly and efficiently. Parallelingthese electronic transactions is the growing usefor computer programs which allow analysts tocompile, filter, sort, chart, and perform trendanalysis with far greater efficiency than everimagined.

MANUFACTURING STRATEGIES:Trends toward self-inspection of work performed

are also gaining wider acceptance. However,changes in corporate loyalty and a more mobileworkforce tend to mitigate consistency in jobperformance and work quality. The state of theindustry for inspection generally indicates paritywith other heavy manufacturing industries. Inmany instances, inspection documentation withinthe shipbuilding industry is significantly morethorough compared to the private sector.

Setting and Erecting

INTRODUCTION:Setting generally refers to a major evolution in

the assembly stage of shipbuilding where some

combination of positioning and handling operationsare involved. Setting and erecting are terms whichtypically describe those activities that contributeto the final assembly of outfitted structural blocks,the joining of which completes the ship.

STATE OF THE INDUSTRY:The shipbuilding industry generally utilizes cranes

to execute the assembly of ship sections. Setting thesesections relies on accurate weight calculations wherecenters of gravity are determined both longitudinallyand latitudinally. To accomplish this task, a rigorouseffort to identify and calculate weights and momentsis essential. Once this information is determined, aseries of subordinate steps must precede any crane liftbefore setting and joining units can begin. Sizing andlocating lifting pads and lugs that best match thearrangement of lifting bridles for different servicecranes must also match the ship structure. As craneslift and position these ship sections or blocks, activitiesthen focus on accurately setting critical features ofadjacent components to minimize any significantrelocation of structure. Coordination of fitting house-sized blocks demands excellent voice or sightcommunication as well as a wide array of devices tosecure and attach these units to one another.


is underway.


is underway.

ENABLING TECHNOLOGIES:The primary technologies supporting this process

operation are cranes and the devices necessary toattach, measure, and articulate the lifted weight.Different gripping and clamping mechanisms readilyavailable in the marketplace provide the means toconnect cranes to work. Cranes equipped withdynamometers commonly provide feedback on weight,while less sophisticated devices enable surfaces andedges to be joined. Among these devices are a widevariety of welding clips, jacks, clamps, and the likewhich temporarily hold major features and shipcomponents together prior to final joining.

MANUFACTURING STRATEGIES:The ability to lift and set larger units reduces the

need for additional welding across structural blocks

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during erection. Unfortunately, this approach requireslarger, more expensive, high capacity cranes. Thefeasibility and capital cost may present obstacles tothe shipbuilder. As a result, the process of settingblocks relies heavily on planning and engineering tomaximize the limits of size and weight during finalassembly and erection. Managing the informationand analyzing the demand on resources (e.g., cranes)are critical steps in the overall ship constructionstrategy.

Fixturing

INTRODUCTION:Fixturing is a vital process in the overall ship

manufacturing and assembly operations. This processfrequently relies on complex production aides torestrain, clamp, and manipulate production partsduring specific manufacturing operations. To maintaindata points which control dimensional accuracy, acombination of hard and soft production fixtures areusually employed. Because low volume, batchmanufacturing has forced shipyards to rely on lesssophisticated fixtures, tolerances of finished productsare rather inexact compared to other industrialproducts.

STATE OF THE INDUSTRY:Shipbuilding typically uses fixtures throughout

the manufacturing and assembly operations. Formachining operations, certain processes such assurface milling and shaft turning demand specialblocking and indexing. For these work centers,accuracy and repeatability are critical in achievingdesign specifications that often refer to surfacingconditions and flatness/straightness tolerances madepossible only with precise machine tools. For othernon-machining operations (e.g., structural steelassembly), accuracy is often sacrificed using rathersimple, temporary fixtures to aid the productionworker. In these instances, little effort is spent ondesigning and verifying the qualifications for aparticular fixture.

As shipbuilders became more automated, the needfor flexible manufacturing fixtures became moreapparent. The ability to adapt production fixturing tolow volume part fabrication and assembly challengedtraditional concepts. The introduction of robotic arcwelding as a production technology had severalsignificant effects on how shipbuilding would fixtureparts for assembly. Prevalent in pipe and steelassembly shop manufacturing is the use of automated

manipulators capable of synchronized motion controland featuring dual rotating tables that accommodatea wide array of flexible holding fixtures. By adaptingmachining practices, steel assembly can clamp andhold individual parts with the same precision. Thecomplexity and cost for fixturing depends on thecritical features of a particular part design andrequirements for one or more manufacturing steps.For assembly, fixturing is generally uncomplicated.Minimizing tooling requirements and set-up timeswhile achieving favorable working positions are keyto good fixturing, particularly when the parts are200- to 300-ton assemblies (Figure 2-5).


is underway.


is underway.

ENABLING TECHNOLOGIES:Fixture designs have traditionally been developed

by production personnel responsible for producing apart or assembly. CAD/CAM with precise design dataenhances fixture design development. The ability tofit the fixture design to the final part features and theconstraints of known production equipmentsignificantly improves the quality and accuracy of thefinal product. By exercising the product design model,shipyards can also ascertain size, weight, and cost forproposed fixtures while simultaneously developingthe best construction strategy.

Figure 2-5. Fixed Pin Jigs

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MANUFACTURING STRATEGIES:DFMA embodies the philosophy of producing parts

or assemblies with an economy of production.Fixturing relies on the necessity to control the positionand orientation of production parts or assemblies forcertain operations. The results of which reduce laborcosts (e.g., welding out-of-position) while maintainingdimensional control of the finished product. Thisnecessity alone is enough to maintain a fixturingprogram that identifies, designs, maintains, andreconstitutes fixtures for current and futureproduction.

Positioning

INTRODUCTION:Positioning, as a production process in shipbuilding,

almost universally refers to those methods involvedin moving and orienting larger material items toperform a primary or secondary operation. The processtypically involves loading/unloading work-in-process,and accurately positioning dimensional planes,features, or objects relative to a particularmanufacturing or assembly work center. Positioningalso embraces the methods and practices used toinstall components or large-scale, multi-ton objects(e.g., outfitted platforms) by manipulating the volumeof required space to fit the volume of available space.

STATE OF THE INDUSTRY:The shipbuilding industry utilizes a number of

different methods to position and orient work piecesas part of the manufacturing and assembly operations.Besides the use of various style cranes, shipbuildersoften rely on various devices to establish coordinateand spatial positioning. These devices include self-propelled, multi-axis manipulators; indexing tables;multi-ton rollers; jack-and-skid devices; powerconveyors; skid blocks; hydraulic jacks; and weldingclips. Used in combination, these items can achievethe desired position of condition relative to any fixedpoint, regardless of features that may make suchorientation otherwise impossible.


is underway.


is underway.

ENABLING TECHNOLOGIES:The ability to move and position ship components

relies on a variety of conventional mechanical,pneumatic, and hydraulic support equipment. Manyof these applications are uniquely specialized andreflect the development of a special need based on aspecific manufacturing or assembly task. Becauseshipbuilding involves relatively large components,there is widespread innovation in developing ormodifying off-the-shelf products to meet particularneeds. As a result, the range of suppliers is asdiversified as the applications. Sensor technologiescoupled to computer programs that provide operatorfeedback have begun to play a key role in this process.Establishing accurate positioning to within +1 mmfor operations such as cutting and milling is asimportant to manufacturing as maintaining the sametolerance in assembly. Likewise, detecting the relativeposition of a surface, plane, or point is as critical asbeing able to position that object.

MANUFACTURING STRATEGIES:The ability to accurately position an object relies

not only on the devices responsible for manipulatingthat object in space, but also those manufacturingprocesses that contribute toward its physical features.While the range of products that enable shipbuildersto position material and components is diverse, theprimary objective is to execute the process efficientlyand cost effectively with some standard array oftechniques and procedures. Like other supportprocesses, positioning large objects poses challengesto the safety of personnel. As a result, diligence inplanning and executing complex positioning of large,heavy objects is crucial to the overall process.

Grinding and Sanding

INTRODUCTION:Grinding and sanding are similar processes which

are prevalent throughout the manufacturing andassembly operations in the shipbuilding industry.Typically performed with portable or stationarypowered equipment, they are considered to besecondary processes because they remove material aspart of a cleaning or preparatory step (e.g., deburring;removing weld spatter, paint, or paint primer). As afinishing or surfacing process, grinding refers to amore aggressive operation in which larger amountsof material are removed. In cases of precision grinding,numerical control machinery is used to produce finefinishes and/or close tolerances.

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STATE OF THE INDUSTRY:Since the same tools and abrasives can be used for

grinding and sanding, the difference is more a matterof degree than a strict definition of terms. Bothoperations use an abrasive material applied underpower. Grinding involves removal of material and ismost commonly used: (1) to deburr (or dress) roughedges of mating surfaces prior to welding and (2) toblend or fair adjoining surfaces after welding. Theexecution of this operation leaves the final results inthe hands of the mechanic. Most free-hand operationsin a shipyard allow for the use of coarse grits. Theproduction item being ground is either held to thegrinding media or the media is held to the work. Here,no single combination of grit and bonding agent iseffective for all materials or all conditions. The mostpopular used grit is aluminum oxide. However,zirconium oxide has proven to have a longer cuttinglife and a higher cutting speed on steel. The abrasivemedia used depends on the type of work and desiredfinish, which dictates the appropriate grit (orcoarseness) and cutting speed. For grinding, theabrasive media and bonding agent are formed into adisk that is turned at high speeds by a pneumatic orelectric hand grinder.

For sanding, the abrasive is bonded to a paper orcloth, and is turned by a pneumatic or electric-powered hand tool in either a disk or belt form.Sanding is a generally a surface preparation operationwhere paint or rust are removed to prepare forwelding or repainting. A larger variety of grit (orcoarseness) is available depending on the final finish.

STATE OF THE ART:Grinding and sanding are used for final edge

preparation during welding and ship construction.Typical grinders used by shipbuilders are pneumatic/electric and hand held, because most older grindersare heavy and not ergonomically designed. State-of-the-art grinders are lighter, quieter, and designed formaximum operator comfort. Pneumatic grinders arealso more efficient, and use less compressed airvolume. Grinding and sanding consumables haveincreased their effectiveness by incorporatingcharacteristics such as self-cleaning and longer-lastingmaterials.


of the art in grinding and sanding.

ENABLING TECHNOLOGIES:To grind or sand a surface regardless of its base

metal or product type (e.g., steel plate, pipe spool,sheet metal) usually requires hand held, portablemachines. These tools can accommodate variousgrinding or sanding wheel sizes and shapes dependingon the application. To improve ergonomics and reduceoperator fatigue, grinding tools are available in threeconfigurations: straight, angle, and surface. Forspecific applications, there is also a range of powersizes varying between one-third and six hp, makingeven the most challenging job relatively easy.Compressed air and electricity are the usual sourcesof power for these tools. However even in the mostrigorous conditions, it is still important to considerthe hazards of using electrical hand tools. Shipbuildingis no exception, particularly when access to smallspaces offers difficult evacuation in the event of a fire.The most popular tool suppliers include Atlas Copco,Ingersol Rand, ATSCO, and Milwaukee.

MANUFACTURING STRATEGIES:Because grinding and sanding processes occur over

a wide range of applications and in differentenvironments, there is no discernable strategy.Generally, the objective is to sustain consistency inthe sourcing and use of abrasive materials for theseprocesses.

Washing and Cleaning

INTRODUCTION:Washing and cleaning involves the use of mild or

aggressive chemical agents to achieve acceptablesurface conditions as a prerequisite for another processoperation. These production processes are used toeliminate rust, scale, oxidation, flux, grease, dust,and/or other foreign particulates. Cleaning certainmaterial types also secures a level of preservationconsistent with expected life cycle requirements.

STATE OF THE INDUSTRY:Stainless steel and copper nickel are typical material

types used in shipbuilding piping systems. Both high-pressure and low-pressure piping systems must meetcertain criteria to perform satisfactorily. Otherproduction materials requiring preservation coatingsalso need to be cleaned to ensure the durability andintegrity of the system over its operating life.

While cleaning remains somewhat unchangedtechnically, the use of more aggressive agents andpreservatives has changed. Rough hand cleaning can

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be achieved using several common agents such asvarsol, acetone, or intex. Neutral cleaning agentslike hot water are also used to remove lubricatinggreases common to production operations. Moreaggressive agents (e.g., sulfuric acid, caustic soda,trisodium phosphate) are typically applied in diptanks designed specifically for the size and type ofmaterial. Tank sizes range six and ten feet in width,20 to 30 feet in length, and five feet in depth. Immersion(or soak) times and temperatures are controlled tosatisfy desired cleanliness, but must be closelymonitored. Statistical process control charts areamong the tools that aide in this process. Timers anddevices for immersing materials into chemical cleaningtanks are relatively unsophisticated, but ofteneffective. General maintenance of such tanks, normallysemi-annually, involves routine flushing andreplenishment of the cleaning agents.

STATE OF THE ART:Cleaning processes and systems are constantly

being improved and optimized to meet the demands ofa wide variety of precision cleaning requirements.High pressure, ultra-high pressure, and immersionsystems have become more automated and customizedto meet specific size constraints, material compatibilityissues, throughput requirements, and other needsspecific to a cleaning application. High-pressurecabinet washers are typically used to clean parts withsimple to medium geometries. Cabinet washers areadvantageous for line-of-sight cleaning of partscontaminated with greases and oils by using aqueouschemistries. Ultra-high pressure cleaning systemsuse pressures in the 15,000+ psi range for veryaggressive cleaning and coatings removal. Immersioncleaning is another process that effectively cleansparts with complex geometries. Bath agitationtechniques such as spray-under immersion orultrasonics can also enhance the cleaningeffectiveness.

STATE OF RELATED INDUSTRY:Many cleaning applications are turning to more

environmentally friendly chemicals and processes asalternatives to traditional solvent cleaning. The useof pressurized water with an environmentally benignchemistry has been effective in cleaning metal partsof all shapes and sizes. The cleaning systems arecustomized and scaled-up or down to fit any size partand accommodate throughput and fixturingrequirements. Another type of cleaning which canremove grease, scale, oils, and oxidation is carbon

dioxide pellets. This method is environmentallyfriendly and does not create an additional wastestream.

ENABLING TECHNOLOGIES:After completing a washing or cleaning process,

organizations can employ various techniques toinspect the effectiveness of the process. Part of thefinal inspection after cleaning is visual. For situationsthat require more robust scrutiny, bore scopes can beused to ensure the integrity and consistency of thefinished process. To maintain the cleanliness offabricated pipe and pipe assemblies prior to actualinstallation, organizations also use several methodsto protect the internal surfaces. The use of polyvinylpipe caps, which act as corks to seal the opposing endsof a pipe detail, works extremely well. Additionally,efforts to seal these caps with tape or fasteners iscommon when ensuring cleanliness over a longerduration. Another alternative is the use of rigorousblanks fashioned from sheet metal.

MANUFACTURING STRATEGIES:Perhaps the only discernible strategy readily

apparent within the shipbuilding industry is thedesire to maintain process zones for similar cleaningagents and cleaning practices. Additionally, the abilityto kit or palletize similar production materials fordownstream use quantifies the demand on washing/cleaning capacity.

Milling

INTRODUCTION:Milling is a primary operation in shipbuilding that

provides surfacing, facing, and edge preparation ofvarious close tolerance piece parts. The process isassociated with the fabrication or manufacture offinished piece parts requiring intricate accuracyobtainable only with computerized numerical controlmachines. As a machining operation, milling machinesare capable of performing gouging or cutting in twoaxes of motion simultaneously. Consumable cuttingtips and rotary cutters operate in a dry or self-lubricated system to remove material at fairly highrates in a series of programmed trajectories acrossthe work piece.

STATE OF THE INDUSTRY:Milling is usually associated with machine shops

where materials are manipulated in a series ofoperations to produce highly accurate piece parts.Milling is also exceedingly important to welding

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operations in shipbuilding. The ability to producebeveled edges on structural plating before they arejoined by welding processes reduces fit-up and weldingtimes. In addition, automated and mechanized weldingprocesses for joint designs use less weld volume thantypical thermal cut joints. These processes haveproven to be exceeding efficient and cost effective ineliminating the required amount of time needed toclean and weld joints.

As a machining operation, milling utilizes abrasivecutters which rotate at variable speeds to cut orremove material along a programmed path (Figure 2-6).Available in different sizes, cutters are generallyfabricated from high strength steel which improvesperformance capability. Heat produced by the cuttingprocess is usually cooled by lubricants, althoughthere are instances where dry cutting can be useddepending on the material grade and thickness. Forwelding, milling steel plated edges includes squarebutt joints; single-V butt joints (45° and 60° includedangles); double-V butt joints (60° included angle); anddouble-U butt joints (36° included angle). Materialtypes which are milled at depths up to two and 5/16inches (e.g., carbon steel; high tensile strength steel;HY steel; high strength low alloy steel) requiredifferent feed and cutting speed rates.

STATE OF THE ART:CNC milling centers are considered state of the art,

and can increase cuttings speeds and feed rates.Characteristics of these new machines include:through spindle coolant, high speed spindles,controllable acceleration/deceleration rates, and rapidtool changing. The latest insert tooling continues toprovide significant increases in material removal.The programming of CNC milling centers also enablescomplex shapes to be fabricated. However, a significantcapital investment is required to purchase machineswhich meet the physical requirements of the shipyardenvironment.

STATE OF RELATED INDUSTRY:The state of related industries is the same as the

state of the art in milling.

ENABLING TECHNOLOGIES:Several proven technologies are involved in milling.

These technologies center on process controls andcutter designs. Newer milling machines featureinteractive controls where displays allow the operatorto pre-select commands from a library of technicalmenus and data. Video displays alert operators to any

abnormal occurrence in the actual operation. Cutterspreviously developed for standard machining havealso been refined for this process operation. Thedesign, configuration, and arrangement of thesecutters is critical to the cost and operational efficiencyof milling.

Recently, nanograin materials (e.g., titanium-aluminum-nitride) have been developed for coatingcutting tools used to machine and mill materials liketitanium. By processing and applying nanophasepowders to cutting tools, tool life can be increasedtwo-fold. This method reduces fabrication costs byincreasing tool longevity, thereby reducing the numberof tool changes and improving adherence tomanufacturing tolerances.

MANUFACTURING STRATEGIES:As a machining operation, milling does not subscribe

to any one manufacturing process. It does, however,suggest that the execution of work performed on oneor more milling machines must be planned at a levelof detail that best describes work content. Determiningthe duration of cycle and idle times is critical toplanning work for CFM.

Bending

INTRODUCTION:Bending, as a production process in shipbuilding,

almost universally refers to the manufacture of pipepiece parts. The process typically involves loadingand unloading stock lengths of pipe into hydraulicallyassisted CNC bending machines that are capable ofbending various wall thicknesses, material types,and diameters. Depending on the level of production,

Figure 2-6. Milling Machine

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the entire process can be automated. Bending alsorefers to sheet metal piece parts that are bent on pressbrake machines capable of creating a desired angle orbend. Modern sheet-metal fabrication also featuresCNC press brakes; however, manual machines aremore prevalent in the U.S. shipbuilding industry.

STATE OF THE INDUSTRY:Pipe bending is one of the critical manufacturing

steps in pipe fabrication. The ability to execute multiplebends (known as 1-D, 2-D, 3-D, 4-D, and 5-D bends)with great accuracy effectively drives the cost of thisshipbuilding operation. Bending machines are groupedaccording to the pipe diameters which they canprocess. For example, a four-inch machine can bendmaterial from two to four inches in diameter withvarying wall thicknesses. Whether mechanicallyoperated, air/hydraulic, electric, or a combination,each machine can handle a range of different materialdiameters and wall thicknesses, also referred to asschedule. Ranging from 14 inches O.D. material witha 0.250 wall thickness down to 0.5 inch O.D. materialtypifies the scope of material processed for shipboardpiping systems.

Induction bending features locally applied heatused to control individual bends rather than the cold-bending process. Depending on the material type(e.g., copper, carbon steel, copper-nickel), smalldiameter pipes from 0.25 inch to one inch O.D. forcertain low-pressure systems are generally hand bentwhen installed shipboard. Bending small diameterpipes on a CNC machine provides a level of accuracyimpossible to achieve with manual hand bendingtools, but it also requires that such piping be fullydetailed in design. The required level of effort may notwarrant this engineering cost.


is underway.


is underway.

ENABLING TECHNOLOGIES:The ability to quickly and efficiently bend pipe

spools into different configurations is important tothe overall cost of manufacturing pipe. Maximizingthe fabrication of bent pipe details eliminates the needto introduce fittings as well as the associated weldingprocess that accompanies naturally occurring joints.So as a manufacturing process, bending is preferred.

Major equipment suppliers of DNC/CNC pipe bendingmachines include Swartz Weirtz and Pines. A numberof press brake machines are also available throughPullmax and others that provide CNC control bendingfor sheet metal.

MANUFACTURING STRATEGIES:For the shipbuilding community, bending operations

occur shipboard as well as in the supportingmanufacturing shops. As a result, the principlestrategy for these production operations is aimed atestablishing work content that is compatible withavailable production capacity and arranging thoseresources accordingly. This principle loosely definesCFM and lean manufacturing, and hinges around theestablishment of manufacturing cells that offer highcapacity with flexibility. Rather than cluster similaroperations in specific areas, the arrangement of theequipment should be dictated by the work contentand the operations needed to produce a family ofparts. This approach would maximize productioncapacity.

Winding

INTRODUCTION:Winding refers to the repair of electrical motors

that require periodic maintenance as part of acomprehensive ship overhaul. Winding, also knownas rewinding, involves both AC and DC motors ofvarious sizes. The process typically entails cleaningarmatures and stators; using solvent baths; coatingor varnishing armatures; and conducting visualinspections to maintain the integrity of electricalmotors.

STATE OF THE INDUSTRY:Shipbuilding, particularly ship repair, places certain

demands on the capabilities of select productionprocesses. One rather critical but low volume processis rewinding electric motors. Motor repair involvesthe removal and disassembly of electrical motors toidentify specific problems. At the heart of an electricmotor is the stator, a series of copper wires woundaround a central cylinder. The rotor revolves aroundthe stator, and together they create the polarity forgenerating electricity. Inspecting and cleaning thestator is critical for extending the life of a motor. Toaccomplish this, the rotor and stator are washed,then baked to establish a clean and dry condition.Ensuring that the copper windings are clean is vitalfor the next step, varnishing, in which the stator isdipped into a bath of the preservative to impede

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oxidation. Visual inspection and testing are also partof the process.


is underway.


is underway.

ENABLING TECHNOLOGIES:Because winding is a limited production process, no

need currently exists for investing in technology toimprove overall efficiency.

MANUFACTURING STRATEGIES:The demand to maintain an in-house winding

process is limited even for the repair and overhaulshipyards. Alternatives such as outsourcing thisprocess are more advantageous, since a strongbusiness case cannot generally be made. As a result,no applicable manufacturing strategy exists.

Cable Pulling

INTRODUCTION:Pulling (or installing) electrical cables that support

shipboard services involves a majority of manualprocesses that have changed little over time. Routingthe wide range of electrical cable sizes that make upthe ship’s power, communications, and generationservices can typically involve miles of cabling. Amajority of the electrical services for militarycombatants includes large diameter, high voltageshielded cabling that runs hundreds of feet betweenconnection points. Recent practices have introducedfiber optic cabling for low voltage communicationssystems.

STATE OF THE INDUSTRY:Cable has traditionally remained unchanged. The

majority of ship service cabling involves armoredcable that runs from source to service. Nearly 100%of a ship’s cabling is manually coiled, hung, pulled,and stretched. Almost all cable is suspended inoverhead areas of the ship, which requires the installerto lay in a prone position in order to snake the cablefrom one point to another. For lengths that exceed400 to 500 inches, the challenge often exceeds thehuman physical limit, thereby resulting in a higher-than-average number of worker’s compensation cases.

Specialized hand tools and techniques aid in cableinstallation, and most often are the products ofexperience and knowledge. To complete the process ofinstalling cable, different commercially availablecutting and crimping tools are used. Portable cablepulling machines facilitate routing cables where spaceand routing paths are reasonably unencumbered.Other practices such as pre-cut cable lengths derivedfrom 3-D product models enable installers to handleonly the length required, thereby eliminating thelabor cost to cut and the material cost to discardexcess cable.


is underway.


is underway.

ENABLING TECHNOLOGY:For commercial applications where general service

cable is installed, pneumatic or electrically poweredcable pulling machines are used. Operation of thesemachines depends largely on available space and theability to position the machine strategically.Commercially available, the machines essentiallypush the cable as it is manually routed by hand alongits pathway. As the cabling is run, additional cablepulling machines grasp and pull the cable so that thenext leg can be routed for the subsequent run. Theadded mechanical advantage enables larger diametercabling to be installed efficiently, while reducing theincident rate of worker’s compensation cases. Becausethere is concern regarding possible damage to costlyship cabling, the powered cable pulling machines aregenerally not used for military combatants.

MANUFACTURING STRATEGIES:A rigorous sequence plan is a necessity for installing

many of the components that comprise a ship’sdistribution system. Placing available resources andmaterial within ship spaces to promote an orderlyexecution of work puts inordinate responsibility onthe planning function. However, the ability anddesire to maintain a fully integrated schedule isdriven by demand. Minimizing the amount of laborspent on non-value added activities is the keystone ofwhat many shipyards are now calling CFM and JITmanufacturing.

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Hydrostatic Testing

INTRODUCTION:Hydrostatic testing (or hydro-testing) involves

pressurizing specific ship components or systems todetermine and validate their structural integrity.Most piping systems on ships are hydrostaticallytested to 1.5 times their operating pressure beforethey are placed into service. Testing involves isolatinga component from adjacent ship systems (e.g., tankor piping system); connecting and applying air orwater pressure; and identifying potential leaks usingleak detection devices. The process is iterative untilthe complete system achieves the required integrity.Testing guarantees system integrity and, ultimately,the crew’s and ship’s safety.

STATE OF THE INDUSTRY:Hydrostatic testing begins during the design

development stage, when ship systems are diagrammedinto schematic drawings that identify specificboundaries for testing. These boundaries establishcritical dimensions of each piping system that willenable testing under shop or ship conditions. Ideally,hydrostatic testing of all piping under a shop conditionwould reduce costs; however, this is not feasible.Piping systems must ultimately be tested as onecontinuous system which can only be accomplishedshipboard.

STATE OF THE ART:The state of the art in hydrostatic testing is

essentially the same as the state of the industry.Sophisticated CAD models and finite element modelanalyses of the piping systems can be conducted tohelp identify whether or not design requirements forthe system are met. These analyses can assist inguiding instrumentation decisions (e.g., strain gages,displacement transducers) and location duringhydrostatic testing, if the integrity of the pipingsystem design is in question. While these modelingtechniques can be employed to assist in determiningthe integrity of these systems, there is no substitutefor hydrostatic testing to ensure the health and safetyof personnel working on and around pressurized shipsystems.

STATE OF RELATED INDUSTRY:The state of related industry in hydrostatic testing

is essentially the same as the state of the industry.

ENABLING TECHNOLOGIES:As a practice, the process of performing hydrostatic

testing remains unsophisticated. After all non-destructive testing (e.g., visual, dye penetrant) iscompleted, hydrostatic testing can usually begin.Testing entails the use of blanks that create anendpoint of the pressurized boundary, which typicallyoccurs at a fitting or valve. A hydro pump is used topressurize the fluid and hold the pressure within theallowable range during the visual inspection.Calibrated relief valves are used to protect the systemfrom inadvertent over-pressurization.

Air or water is then pumped into that section of thepiping system to a pre-determined pressure, normally1.5 times the design system pressure and monitoredbetween five and 30 minutes using a gauge. Permanentdeformation of a component or leakage through abrazed, soldered, swaged, or welded joint isunacceptable. These discrepancies must be repaired,and the item is retested at full hydrostatic pressure toprove the integrity of the repair. Mechanical jointleakage (e.g., O-rings, flange gaskets) is not a causefor test failure. These joints can be repaired after thehydrostatic test and be proven tight with a test atnormal system operating pressure.

As ship piping systems evolve and extend into alarger number of ship spaces, incremental testing isperformed. Final hydrostatic testing is mandatory toguarantee the integrity of the entire piping system.To accomplish this process, a low pressure air test isperformed to assure that nothing has been left openand all the valves are positioned correctly. After thelow pressure test has been satisfactorily completedand all problems corrected, final system hydrostatictesting is initiated. Until all discrepancies areidentified and corrected, hydrostatic testing continuesas an iterative process. Hydrostatic testing is thesecond step in a progressive test program. The systemis inspected to ensure that it is complete and built inaccordance with the applicable drawings anddirectives. After hydrostatic testing, the system isflushed to establish the required system cleanliness.Operational testing is then performed to prove thatthe system operates as designed. The final testingbefore sea trials is a demonstration that all of theindividual systems will work together to support thetotal operation of the ship. An extensive sea trial isthen conducted to demonstrate that the ship willperform as designed. In addition to hydrostatic testing,certain pipe systems can require flushing, a drop test,and/or an operational test as well as a turn-overinspection.

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MANUFACTURING STRATEGIES:Ensuring the health and safety of personnel working

on and around pressurized ship systems is key to anymanufacturing approach. During the assembly ofpiping systems, size and complexity require thatcertain safeguards are in place to facilitate testing.Inaccessibility to critical weld joints that join pipefittings on large, thick-wall high pressure systemsdemands that hydrostatic testing must be performedsystematically. To accomplish this task, accuraterecords which document test completion results mustbe maintained throughout the ship’s constructionschedule and process. Also exceedingly important isthe use of a highly visible tagging system that alertsthe workforce to the status of either tested orpotentially dangerous conditions.

POINTS OF CONTACT:For further information on SP-16 Panel items in

this report, please contact:

Mr. Joseph Bart SicklesConcurrent Technologies Corporation(814) [email protected]

Mr. Allan G. RoyNewport News Shipbuilding(757) [email protected]

CHAPTER SUMMARYTechnological developments in ship construction

and welding have been intrinsically linked throughoutthe century. In many cases, it is difficult to identifywhether a welding development enabled a new shipdesign or whether an innovative ship technology wasthe driving force for a welding development.

Welding developments in the shipbuilding industryhave been accelerated by various events, most notablythe two World Wars. During World War I, the newlyevolving electric arc welding processes were provento be essential tools that supported the war effort,especially in the construction of ships and other steelstructures. As a result, the American Welding Societyunder the leadership of the War Department wasestablished immediately following the end of the war.Likewise, World War II placed new demands on thewelding industry to develop new processes andmaterials so large numbers of ships could be producedannually under a compressed construction schedule.Among the technologies that gained impetus for rapiddevelopment from the war effort were reducedhydrogen electrodes and submerged arc welding.

As with most technologies, the rate of innovationand advancement in welding has accelerated in recentyears. Again, the shipbuilding industry’s needs havebeen a major driving force in these developments.Modern ship designs are continuing to incorporatenew materials which, in turn, require comparablenew welding materials. Global competition in shipconstruction has also demanded more productive andefficient automated systems. Although U.S. shipyardshave not incorporated the same level of robotics andautomated systems as their internationalcounterparts, the United States has been andcontinues to be the leader in implementing advancedwelding materials. This effort has primarily occurredbecause of the stringent requirements of the U.S.shipbuilding defense industry.

Beveling

INTRODUCTION:Beveling is a process that prepares material surfaces

(e.g., plate edges that form a joint) for welding toensure a quality full penetration weld or, in somecases, the correct depth of penetration. In addition,

this angular edge preparation permits greater accessto the root of the joint and easier manipulation of thewelding torch. Beveling is achieved for block assembly,erection beams, and other subsequent weldingpractices through milling, grinding, and cuttingmachines.

STATE OF THE INDUSTRY:In shipbuilding, beveling occurs at various stages

in the first operations as well as subsequent and finalassemblies. These processes can be applied in a shop,shipyard, or on-board environment. Historically infirst operations, plate edges are beveled during theflame cutting processes. With the advent of plasmacutting, many of these systems could not provide thenecessary bevel, so a secondary operation was addedto the production line. Recently, improved torchholding fixture designs; advanced plasma cuttingtorch designs; and better control software have beenincorporated into modern plasma cutting systems. Asa result, plasma cutting tables can now producebeveled edges in a single cutting operation.

For many U.S. shipyards, the legacy CAD designsdo not include beveling commands in the machineoperational codes. Although the technology isavailable, many refrain from implementing the practicedue to re-engineering requirements. Shipyards whichhave recently re-capitalized and re-engineered theirdesign efforts are using the bevel capabilities ofplasma cutting processes during some first operations.Most of these are foreign shipyards; however, AvondaleShipbuilding, Newport News Shipbuilding, IngallsShipbuilding, and the Alabama Shipyards haveincorporated robotic plasma beveling into their beam-cutting first operations shops.

Laser beam cutting is emerging as a process forfirst operations joint preparation. VosperThorneycroft (UK) routinely uses laser cutting forinitial plate preparation. Bender Shipbuilding isimplementing a six-kW cutting system at its Mobile,Alabama facility. Although the latter situation istargeted for commercial shipbuilding applications,the system is only being applied to a limited numberof ship and weld joint designs which capitalize oncutting technology.

Currently, neat-cut processing and accuracy controlin the shipyards have not progressed to the point

S e c t i o n 3

Welding Technologies (SP-7 Panel)

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where all cutting and beveling can be performedduring first operations. Bevels for subsequent andfinal assemblies are still achieved through manualcutting and grinding on-board ship. In addition,many welds must be back-gouged to provide a bevelon the second side of the weld joint. Back-gouging issimilar to either carbon arc-gouging or oxy-fuelcutting torches typically used to prepare the backsideof a weld. Some subsequent grinding may also berequired. For aluminum and other non-ferrousmaterials, mechanical milling tools or plasma torchesare used.

STATE OF THE ART:The state of the art is the same as the state of the

related industry.

STATE OF RELATED INDUSTRY:Like shipbuilders, heavy equipment manufacturers

(e.g., Caterpillar, JI Case, Deere & Company) routinelyapply CNC plasma and laser beam cutting for firstoperations processing of similar steel alloys andthicknesses. The key driver is the extensive use ofautomation in their manufacturing operations. Theaccuracy of plasma and laser beam cutting, combinedwith the accuracy control of other processing andincoming material, provide the precision andrepeatability necessary for robotic welding withoutfeedback control. Most of these manufacturers’assemblies are smaller than the typical ship block.Fabricators in the construction industry largelyemploy the same practices and techniques for bevelingas do the shipbuilders for final assembly.

ENABLING TECHNOLOGIES:CNC and robotic systems for first operations beveling

are well established technologies, although not widelyimplemented in U.S. shipbuilding. However, portableprocessing equipment is currently not available forproducing weld preparations of plate and erectionbeams on-board ship.

MANUFACTURING STRATEGIES:Ideally, all cutting and beveling should be performed

in first operations with all components neat-cut forinitial and final assemblies. But until the accuracycontrol of subsequent processing and incomingmaterial advance to that point, the need fortechnologies to trim and bevel assemblies in theshipyard will still exist. To enhance U.S.competitiveness, manufacturing strategies need toaddress the arduous portions of the process flow,

specifically the time-consuming, skill-dependentmanual operations and the delays caused by thedifficulties of preparing final assembly joints duringthe final assembly operations and outfitting.

Fitting

INTRODUCTION:Fitting is the alignment and placement of parts to

be welded. This process is one of the most importantoperations for cost effective welding. The overalldimensional accuracy of ship structures is directlyrelated to the accuracy and adequacy with whichparts are aligned prior to welding and held in positionduring the welding operation.

For the most part, fitting tools and methods areconsistent across the steel working industries. Insome cases, special design tools and devices havefound uses at individual facilities. However, the basicmethods of plate alignment, tack welding, and in-process support of the pieces to be welded have notsignificantly changed over the years.

STATE OF THE INDUSTRY:The shipbuilding industry uses most of the same

fitting devices and techniques as those of similarindustries. The size of ship structures, however, maylimit the adequacy of those fitting devices andtechniques. For example, the stackup tolerances canbe significant when one considers the combined effectof minor fit-up irregularities on the overall dimensionsof the finished vessel. Additionally, the sheer size ofthe ship structures requires many subassemblies orblocks. Then the major concern is the fitting ofindividual blocks together, each with multiple weldjoints that must be aligned at erection joints.Consequently, minor fit-up variations in thesubassembly stage can result in major fabricationchallenges as each subsequent manufacturing stepoccurs.

On panel lines, many U.S. shipbuilders employmechanized devices for aligning plates for one-sidewelding of butt joints and the placement of stiffenerson those panels. In most cases, the parts are tackwelded in place to hold the alignment during thewelding operation. For erection joints, the parts areheld in place with strongbacks (a temporarily attachedstructural member that straddles the weld joint) tomaintain the proper alignment for welding. Thestrongbacks are usually attached to the structuralmembers using fillet welds but, in some cases, speciallydesigned strongbacks are mechanically fastened to

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short tee-headed studs which are arc stud welded tothe members to be aligned.

The importance of fit-up on the fabrication efficiencyand overall dimensional accuracy of a vessel is wellestablished. Significant effort is being put forth todevelop manufacturing techniques to minimize oreliminate the need for fit-up aids. Currently, thesubsequent removal and cleanup of anchoring devicesresult in blemishes on the surface of the finishedcomponents. More information on this technologycan be found in the Study of Fitting and Fairing Aidsof U.S. Shipyards: NSRP Report #0195.

STATE OF THE ART:Given the constraints of the shipbuilding industry

and the types of components being fabricated, thestate-of-the-art fitting techniques and devices beingused are as sophisticated and effective as those ofother industries. One technique applicable toshipbuilding is the use of a specially designed tab-and-slot configuration for assembling T-joints. Ideallyfabricated with laser beam cutting, the design of thetab is such that it can provide an interlock, onceinserted through the slot and twisted. This designresults in self-fixturing and creates an effectivepositioning for welding. Some heavy equipmentapplications have achieved good results with thismethod.

STATE OF RELATED INDUSTRY:The shipbuilding industry is at least as advanced as

other related industries in the area of fitting forwelding.

ENABLING TECHNOLOGIES:Enabling technologies would include any method

which improves first operations and subassemblyaccuracy, resulting in erection joints that fit moreeasily. If improved first operations could not alleviateall fit-up issues, then equipment which can alignbeams and plates during erection would also benecessary. Such equipment must be portable, accurate,simple to operate, provide easy accessibility to theweld joint, and be secured to the work piece in sucha manner that tear-down and cleanup is minimized.

MANUFACTURING STRATEGIES:Manufacturing strategies would include any method

which improves the accuracy control during theinitial stages of fabrication. Another approach wouldbe to design components that can be fitted using thetab-and-slot configuration technology.

Shielded Metal Arc Welding

INTRODUCTION:Shielded metal arc welding (SMAW) is a process

that produces coalescence of metals by heating themwith an arc between a covered metal electrode and thework pieces, and obtains shielding from thedecomposition of the electrode covering. As theelectrode melts to form the weld, the coatingdecomposes into a gaseous atmosphere to shield theweld from contamination while molten, and thenforms a slag to protect the weld as it solidifies andcools. Although it is one of the oldest arc weldingoperations, this process is also one of most durablefor structural and pipe applications.

The shipbuilding industry has been a leader in theuse of SMAW. Many advancements in new weldingelectrodes have been implemented because of SMAW’smulti-applicability to high strength steels and theclimatic environmental challenges common toshipyards. The shipbuilding industry is implementinghigh yield structural steel covered electrodes whichhave higher toughness and more cracking resistance.SMAW is the preferred process for shorter welds andtack welding because of its quick setup and widechoice of electrodes.

STATE OF THE INDUSTRY:Before the advent of welding automation and

robotics, foreign shipyards often employed a variationof SMAW referred to as gravity welding. In thisprocess, a long covered electrode is inserted in aspecially designed electrode holder which enables theelectrode to feed itself along a weld joint, once the arcis initiated to produce a fillet weld. Gravity weldingpermits a single operator to run multiple unitssimultaneously. This technique has seen limited usein U.S. shipyards, mainly because mechanizedprocesses such as flux cored arc welding are beingused instead.

Although efforts are being made to replace it withmore productive welding processes where appropriate,SMAW is still widespread throughout the shipbuildingindustry. The process is particularly extensive fortacking and pipe welding applications. SMAW requireslittle physical equipment at the welding location,making it the process of choice for those applicationswhere access is limited.

STATE OF THE ART:The state of the art of SMAW is essentially the same

as it was in 1990. One improvement has been in the

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area of electrode coatings for low hydrogen electrodes.Versions of these electrodes now exist in which thecoating is formulated with components that are lesshygroscopic, meaning that they are less susceptibleto moisture pickup when exposed to the atmosphere.Referred to as moisture resistant versions, theseelectrodes are capable of maintaining their lowmoisture content for longer periods of time withoutstorage in a heated electrode oven. With the advent ofmoisture resistance versions, low hydrogen electrodesare now purchased according to a prescribed moisturecontent. Designated as -H4, -H8 or -H16 types, thenumber indicates the expected maximum amount ofdiffusible hydrogen in terms of mm3/100g.

STATE OF RELATED INDUSTRY:The use of SMAW by related industry is quite

similar to those of the shipbuilding industry. In fact,many industries have benefitted from the developmentsrelated directly to ship construction and repair.Despite being displaced by more productive processesin certain applications, SMAW is extensively used inrelated industry. SMAW provides quick setupcapabilities; works well in applications where accessis limited; and offers users a wide range of electrodesincluding moisture resistance versions. The processis also advantageous for welding certain alloymaterials when consumables are unavailable forother, more efficient welding processes.

ENABLING TECHNOLOGIES:Enabling technologies related to SMAW is rather

limited. The exception would be the continuingadvancement of moisture resistant versions of lowhydrogen electrodes.

MANUFACTURING STRATEGIES:Most manufacturing strategies are aimed at

replacing SMAW technology with processes thathave higher productivity. However, SMAW willcontinue to play a role in applications where access islimited and/or small amounts of welding are necessary.

Gas Metal Arc Welding

INTRODUCTION:Gas metal arc welding (GMAW) is a process that

produces coalescence of metals by heating them withan arc between a continuous filler metal electrode andthe work pieces, and obtains shielding entirely froman externally supplied gas. This process is a primarymethod for fabricating ship structures, and is usedextensively for piping and pressure vessel components.

STATE OF THE INDUSTRY:GMAW is very flexible, in that changes in the

voltage-amperage relational curves and power supplycapacity can provide quality welds in many materials.This process can perform welding in all positions,either manually or in various robotic or mechanizedforms.

The joining of high yield structural steels is oneexample of a critical shipbuilding application thatuses GMAW. Because the U.S. Navy imposes strictrequirements for shock resistance; static and fatiguestrengths; low temperature toughness; and lowdiffusible hydrogen contents, GMAW is optimal touse. The most stringent scenario for the joining ofhigh yield structural steels is in submarineconstruction. General Dynamics’ Electric BoatDivision is one of the premier GMAW fabricators inthe world. Although some applications cannot beeconomically applied in broader shipbuilding uses,many U.S. shipbuilders are competitivelyimplementing GMAW for general production use.

Two-wire GMAW processes (variations on the single-wire process) are achieving higher deposition rates;reduced distortion due to lower heat inputs, and goodmechanical properties to the application involved.Due to the higher travel speeds associated with theseprocesses, they must be mechanized or used withrobotics. Current applications in European shipyardsinvolve panel lines.

STATE OF THE ART:For critical applications, manufacturers of boiler

and pressure components are very competitive withthe shipbuilders in the fabrication of high strengthalloys. Many of the manufacturers’ developmentscame about from their prior experience in producingcomponents for the nuclear U.S. Navy. Theseapplications take advantage of recent advances inmicroprocessor-based power supplies. Thesophisticated technology provides greater controlover power output and feedback, allowing a singlepower supply to be used in a variety of positions, withvarious types of materials, and with a high level ofprocess robustness.

STATE OF RELATED INDUSTRY:In several countries, GMAW is the dominant welding

method for structural connections for building andbridge erections. This process is also widely applied inthe automotive and light manufacturing industriesfor thicker-section welding applications.

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ENABLING TECHNOLOGIES:To meet ongoing requirements for increased

productivity, shipbuilders need to rely on continuedadvancements in GMAW process controls,consumables, and power supplies to improve processrobustness (e.g., increase throughput, reduceinspection); increase deposition rate; and controldeposition and heat input to accommodate new steeldevelopments and design (weld size) requirements.Shipyards would also benefit from advances inemerging technologies that integrate weldingengineering with other ship design and productionprocesses, such as:

• Advances in statistical process control andnumerical advancement approaches to allow therapid development, qualification, and applicationof welding procedures.

• Automated storage, retrieval, and selection ofwelding procedures and process information.

• CAD technology which includes weld processrequirements (e.g., material selection, joint design,access for welder or process automation), andaccommodates weld-induced residual stress anddistortion into the ship product model.

• Improvements in cutting, beveling, fitting, andaccuracy control to produce accurate, repeatablejoint preparations that are easier to weld bymanual or automated GMAW.

• Reduction in the production of or improvementsin the extraction of welding fume. In addition,emerging OSHA and EPA regulations pertainingto worker’s exposure to chromium, manganese,and nickel will significantly impact the ability ofshipbuilders to use these processes.

MANUFACTURING STRATEGIES:GMAW advancements are driven by:• Changes in steelmaking practices which require

different filler metal chemistries and weldingheat inputs for meeting structural requirements.

• More stringent design and product requirementsfor fairness and dimensional control. Thisadvancement demands a more precise control ofweld size and heat inputs.

• Increased difficulty in hiring and training qualifiedwelders, which requires high levels of processrobustness to accommodate welders of varyingskill levels.

• Increased levels of mechanization and hardautomation, which also require high levels ofprocess robustness.

• Incorporation of welding into the shipbuildingenterprise. Welding process requirements andimpacts must be incorporated into the electronicship product model.

The U.S. shipbuilding industry is represented as asmall percentage of the welding equipment and fillermetal market. As a result, the shipbuilding industryneeds to take advantage of developments driven byother industries. The ultimate choice would be topurchase welding consumables produced undercommercial specifications, as this would significantlyreduce material costs.

Flux Cored Arc Welding

INTRODUCTION:Flux cored arc welding (FCAW) is a process that

produces coalescence of metals by heating them withan arc between a continuous filler metal electrode andthe work pieces, and obtains all or partial shieldingby a flux contained within the tubular electrode. Oneadvantage of this process is its ability to weld throughpre-construction paint primers with an acceptableweld quality, making it the process of choice in manyshipyards.

STATE OF THE INDUSTRY:FCAW is a primary method for fabricating ship

structures. Although most shipyards use gas-shieldedelectrodes, other industries (e.g., buildingconstruction) typically use materials that do notrequire a shielding gas. The choice depends on thematerial properties required for the application andthe physical limitations of the workplace.

The shipbuilding industry has historically hadmany products created for specific applications. Amongthem are electrodes with fast freezing slags to facilitateall-position welding; products with low diffusiblehydrogen deposits; and materials with low-temperature notch toughness. One advantage ofFCAW is its ability to weld through pre-constructionpaint primers with an acceptable weld quality, makingit the process of choice in many shipyards. Becausewelding manufacturers can readily modify fluxcompositions to adapt to emerging shipyard needs,FCAW is expected to continue playing a major role inship fabrication.

Internationally, the recent trend for shipbuilders isto use FCAW as a replacement for either shieldedmetal arc welding or gas metal arc welding. Japaneseshipyards that extensively use automated processesemploy flux-cored electrodes because the deposition

39

rates and operating characteristics are especiallysuited to automation. Flux-cored electrodes haverecently been qualified for U.S. military shipbuilding;however, they are not widely used yet due to the lagin implementing robotics in U.S. shipyards.

STATE OF THE ART:The best state of practice in the best U.S. shipbuilders

rivals the state of the art worldwide.

STATE OF RELATED INDUSTRY:Heavy equipment manufacturers currently apply

many of the same approaches for FCAW as doshipbuilders. FCAW is a dominant welding methodfor structural connections for building and bridgeerections in some parts of the United States.

ENABLING TECHNOLOGIES:To meet ongoing requirements for increased

productivity, shipbuilders need to rely on continuedadvancements in FCAW process controls,consumables, and power supplies to improve processrobustness (e.g., increase throughput, reduceinspection); increase deposition rate; and controldeposition and heat input to accommodate new steeldevelopments and design (weld size) requirements.Shipyards would also benefit from advances inemerging technologies that integrate weldingengineering with other ship design and productionprocesses, such as:

• Advances in statistical process control andnumerical advancement approaches to allow therapid development, qualification, and applicationof welding procedures.

• Automated storage, retrieval, and selection ofwelding procedures and process information.

• CAD technology which includes weld processrequirements (e.g., material selection, joint design,access for welder or process automation), andaccommodates weld-induced residual stress anddistortion into the ship product model.

• Improvements in cutting, beveling, fitting, andaccuracy control to produce accurate, repeatablejoint preparations that are easier to weld bymanual or automated FCAW.

• Reduction in the production of or improvementsin the extraction of welding fume. In addition,emerging OSHA and EPA regulations pertainingto worker’s exposure to chromium, manganese,and nickel will significantly impact the ability ofshipbuilders to use these processes.

MANUFACTURING STRATEGIES:FCAW advancements are driven by:• Changes in steelmaking practices which require

different filler metal chemistries and weldingheat inputs for meeting structural requirements.

• More stringent design and product requirementsfor fairness and dimensional control. Thisadvancement demands a more precise control ofweld size and heat inputs.

• Increased difficulty in hiring and training qualifiedwelders, which requires high levels of processrobustness to accommodate welders of varyingskill levels.

• Increased levels of mechanization and hardautomation, which also require high levels ofprocess robustness.

• Incorporation of welding into the shipbuildingenterprise. Welding process requirements andimpacts must be incorporated into the electronicship product model.

The U.S. shipbuilding industry is represented as asmall percentage of the welding equipment and fillermetal market. As a result, the shipbuilding industryneeds to take advantage of developments driven byother industries. The ultimate choice would be topurchase welding consumables produced undercommercial specifications, as this would significantlyreduce material costs.

Submerged Arc Welding

INTRODUCTION:Submerged arc welding (SAW) is a process that

produces coalescence of metals by heating them withan arc (or arcs) between a bare metal electrode (orelectrodes) and the work pieces, and obtains shieldingby a blanket of granular, fusible material on the workpiece. By using special equipment, shipyards haverefined this technique so that all welding can beperformed from one side and the cost of turningcompleted panels is avoided.

The first real production application of SAW was tosupport the U.S. war effort by quickly constructingships during World War II. Since then, SAW hasgrown in popularity for many applications at shipyards.Both U.S. and foreign shipyards use this process tomake miles of flat position welds in panel shops,platens and on ship assemblies, when possible.

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STATE OF THE INDUSTRY:In shipbuilding, the primary use of SAW is in the

joining of plates to produce panels for hulls andbulkheads. This process is typically applied by speciallydesigned panel welders who incorporate platepositioning, weld joint backup, and mechanizedwelding. As a result, plates as thick as 30 mm can bewelded from one side in a single pass by simultaneouslyemploying multiple electrodes. In addition, almost allU.S. shipyards are using SAW to weld erection jointsby mechanizing the process’ various types of tractorunits.

Some T stiffeners are fabricated from plates usingthe process, whereby double fillet welds aresimultaneously applied by systems that hold the weband flange in the proper position for welding in thehorizontal fillet position. In some cases, SAW may beused for the attachment of stiffeners to hull panels.

Through SP-7 funding, procedures have beendeveloped for the use of SAW for one-side welding oferection joints, using a combination flux/copperbacking and the addition of iron powder for jointfilling. The methods for this application have receivedAmerican Bureau of Shipping approval and have beensuccessfully used in a field application at NationalSteel and Shipbuilding Company.

STATE OF THE ART:The state of the art for SAW does not vary widely

from industry to industry. Some enhancements havebeen made in power source, joint tracking, volumetricanalysis, automatic adjustment, and welding headimprovements/developments in the area of weldingconsumables. These enhancements are minor in termsof advancing the SAW technology beyond its currentapplication.

STATE OF RELATED INDUSTRY:SAW is well suited for the joining of thick sections

of carbon and low alloy steels. Consequently, theprocess has a wide range of uses in various industriesand applications. Other related applications whereSAW is currently used include pressure vessels;heavy wall large diameter piping; boiler waterwalls;field-erected steel storage tanks; and structural steelplate and box girders for buildings and bridges.

SAW is most effective when applied in a flat weldingposition. This trait becomes a major limitation becausemost of the horizontal seams in steel storage tanks,welded by SAW, require specially designed equipmentto provide support of the granular flux, as it provides

the necessary shielding in this position. This sametechnique could be applied for the welding of shipjoints in this same position during fabrication.

ENABLING TECHNOLOGIES:Enabling technologies would primarily be limited

to those which provide advancements in equipmentand consumables. One way to improve productivity isto develop steelmaking technologies that producesteels that would permit the use of welding processeswith higher heat inputs and deposition rates.Currently, weld properties are acceptable, but basematerial properties degrade at high heat inputs.

MANUFACTURING STRATEGIES:Manufacturing strategies for SAW would include

the implementation of designs and practices thatallow for a greater use of this very high productivityprocess, even during the erection stages of shipbuilding.

Gas Tungsten Arc Welding

INTRODUCTION:Gas tungsten arc welding (GTAW) is a process that

produces coalescence of metals by heating them withan arc between a non-consumable tungsten electrodeand the work pieces, and obtains shielding by a gas.The shielding gas is fed through the torch to protectthe electrode, the molten weld pool, and the solidifyingweld metal from atmospheric contamination. GTAWhas also been developed to provide a finely controlledweld puddle for more critical applications.

GTAW produces superior quality welds and can beused to weld almost any metal. Its ability toindependently control the heat source and filler metaladditions provides excellent control of root pass weldpenetration for critical applications. Although it isnot considered a high deposition process, GTAW caneffectively be used on thin sheet metal, piping, orcritical connections. All shipyards use this process.

STATE OF THE INDUSTRY:In the shipbuilding industry, GTAW is often used for

pipe connections. The process provides high quality welddeposits which are critical for pressure piping. GTAW canbe applied manually or by mechanized orbital welders.This flexibility makes it suitable for the pipe shop on-boardships.

Due to low deposit rates, GTAW is not used to weldplate or structural members. Additionally, this processhas difficulty in properly shielding the weld zone indrafty environments. Special care should be taken toeliminate drafts in an open environment.

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STATE OF THE ART:Industries with critical welding applications (e.g.,

aerospace industry) rely heavily on the GTAW process.As a result, these industries employ automaticcontrols, vision sensors, penetration control sensors,seam trackers, and arc length controls to ensure thehighest weld quality obtainable.

Numerous improvements in welding power sources,including inverters and pulsed/variable polarity AC,are available. Shielding gas mixtures have also beenidentified for improved welding performance. Orbitalgas tungsten arc welders provide consistent,controllable performance for pipe welding.

STATE OF RELATED INDUSTRY:In some industries, GTAW has similar applications

to those in shipbuilding. For example, manufacturersthat make equipment for the International SpaceStation rely heavily on this process for the precisewelds required in tubing and pipe lattice designs. Onthe other hand, heavy manufacturing industries,such as construction equipment manufacturers andpressure vessel manufacturers, rarely use GTAWexcept for pipe connections.

ENABLING TECHNOLOGIES:Enabling technologies include:• GTAW flux for increased weld penetration and

reduced distortion to provide increased potentialfor the GTAW process. This flux greatly increasespenetration which, in turn, decreases the amountof distortion by reducing the required total heatinput. Costly joint preparation requirements forthicker section welding are also reduced.

• Improvements in penetration control systems,vision sensors, and seam trackers will providemore accurately welding critical components. Inthe past, these types of control systems have notbeen proven to be sufficiently rugged to withstandthe shipyard work environment.

• Cold wire and hot wire filler metal feed systems toimprove deposition rates.

MANUFACTURING STRATEGIES:The overall quality and productivity of GTAW can

be increased by implementing the use of orbitalwelding equipment, GTAW fluxes, penetration controlsystems, and other process sensors. Although it is ahigh quality welding process, GTAW is rarely used inheavy manufacturing due to its inherently lowdeposition rate. The identification of critical weldssuch as in piping and pressure containment arecandidates for the GTAW process.

Stud Welding

INTRODUCTION:Stud welding (SW) is a process that produces

coalescence of metals by heating them with an arcbetween a metal stud or similar part and the workpieces. This process can be performed manually withthe use of a hand-held welding gun or by mechanizedequipment for high production applications. SW caninvolve other welding processes including arc,resistance, friction, and percussion.

STATE OF THE INDUSTRY:SW greatly facilitates the attachment of mounting

devices such as insulation pins, pipe hangers, andlight foundation threaded fasteners. This process isvery simple in its design, and can effectively andeconomically provide a quality attachment. SW is ona steady growth curve in shipyards. Each year, newapplications are being developed to implement studwelds. For example, shipyards are now using SW tosecure attachment pins for alignment tooling duringthe fitting process.

STATE OF THE ART:Commercially available SW equipment is

consistently applied across industries.

STATE OF RELATED INDUSTRY:Related industries (e.g., bridge and building

construction) heavily rely on SW for the attachmentof thousands of shear connectors. Many householdappliances require stud welds to attach boltconnections.

ENABLING TECHNOLOGIES:While reliable, SW is sensitive to the material and

the surface condition of the components being joined.For manual applications, the equipment and associatedcabling are fairly heavy. Operator fatigue can resultin misalignment of pins and poor weld quality. Newertechnologies, such as friction stud welding, permiteasier attachment of dissimilar and hard-to-weldmaterials, and may be used underwater to supportthe oil industry. Power supplies are being developedwith the capacity to store multiple programs andprovide electronic controls for the process. To facilitatethe application of small diameter pins for insulation,an automatic feed system has been developed in arecent NRSP SP-7 funded project. This systemprovides numerous pins to the gun without requiringthe operator to load each pin individually. Lighter

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weight guns and power supplies can be developed totake advantage of newer lightweight, heat resistantmaterials and microprocessor technologies.

MANUFACTURING STRATEGIES:SW continues to find new applications as the

productivity and effectiveness of the process increases.The process provides a wide range of flexibility in thetype of components which can be attached, and canreliably be implemented with a minimum of training.

Electrogas and Electroslag Welding

INTRODUCTION:Electrogas welding (EGW) is a process that produces

coalescence of metals by heating them with an arcbetween a continuous filler metal electrode and thework pieces. Electroslag welding (ESW) is a processthat produces coalescence of metals with molten slagthat melts the filler metal and the surfaces of the workpieces. These high deposition processes were commonlyused to join the long vertically positioned joints inships with a relatively flat-side shell profile. Bothwelding methods start at the bottom of the joint andcontinue vertically upward as the welding processproceeds, thereby filling the joint with a single pass.Although their use is declining due to new shipdesigns and alterative methods, EGW and ESWwelding are gaining popularity in the bridge andbuilding construction industries.

STATE OF THE INDUSTRY:In the United States, only one shipyard still uses

EGW and ESW for ship construction. This shipyardproduces prototype double-hull blocks for tankerconstruction. A unique design, combined with theEGW process using flux-cored electrodes, allows forthe welding of more than half of the primary welds ofthis ship structure. The ESW process has been adaptedto the cladding of propulsion shafts, as a substitutefor sleeving the shaft with a dissimilar material.

STATE OF THE ART:In the past, many industries used or experimented

with either EGW or ESW. However, the inherentlypoor mechanical properties of the completed weldstended to outweigh the productivity benefits of theseprocesses. The effort came to a standstill in 1979when the failure of an ESW weld in a major interstatebridge girder nearly caused the total failure of thebridge. Since that time, the bridge industry hasbanned the use of ESW. The negative publicity

curtailed the use of both processes, except in thosecases where the expected weld properties wereconsidered adequate for a given application.

Several years ago, the Lincoln Electric Companyintroduced its vertishield process, a self-shielded,flux-cored electrode version of EGW. The vertishieldprocess has been used for a limited number ofstructural applications. Within the past few years,the Federal Highway Administration has fundedresearch for an ESW version that can produce weldswith properties acceptable for bridge construction.The version employs a very narrow joint root openingso that the overall heat input required is significantlyless, resulting in dramatic improvements in mechanicalproperties.

STATE OF RELATED INDUSTRY:Although not extensively used, EGW and ESW

have a few minor applications in other industries.Most of these applications involve the joining of thickcastings or plates, where resulting mechanicalproperties are not of great concern.

ENABLING TECHNOLOGIES:Enabling technologies of EGW and ESW would

include the further development of consumables andtechniques that would result in mechanical propertyimprovements.

MANUFACTURING STRATEGIES:The consumables and techniques of EGW and ESW

need to be further developed to satisfy the performancerequirements of shipbuilding regulators. Onceachieved, the ship structures would then need to beredesigned to permit implementation of these highproductivity welding processes.

Plasma Arc Welding

INTRODUCTION:Plasma arc welding (PAW) is a process that produces

coalescence of metals by heating them with aconstricted arc between an electrode and the workpiece (transferred arc), or between the electrode andthe constricting nozzle (non-transferred arc). Thearc is constricted by passing it through a water-cooled orifice. The orifice gas forces the arc throughthe orifice, which becomes ionized and produces aplasma jet. The arc also has a higher energy densitydue to the constriction and plasma gas velocity.Shielding is obtained from the hot, ionized gas issuingfrom the torch which may be supplemented by an

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auxiliary source of shielding gas. PAW has proven tobe very robust for high volume automation weldingoperations due to its recessed tungsten electrode,which provides longer operating times.

While similar to GTAW, PAW has some advantages.PAW uses a pilot arc established between the electrodeand the constricting nozzle, which eliminates theneed for high frequency to start the arc for each weld.Its tungsten electrode is recessed within the torch,thereby protecting it from contamination comparedto the open electrode of GTAW. Additionally, plasmais less sensitive to torch standoff and can achievefaster welding speeds than GTAW. One possibledrawback is the larger torch size that may lead toaccessibility problems.

STATE OF THE INDUSTRY:PAW is not commonly used in the shipbuilding

industry. Practical applications are usually limitedto pipe shops and the welding of ductwork. GTAWhas proven to be more flexible for the range ofapplications in shipyards. Mechanization andautomation, such as orbital tube and pipe weldingequipment, have typically been built based on theGTAW process.

STATE OF THE ART:The state of the art variation of PAW, known as

variable polarity plasma arc (VPPA), may provefeasible in the shipbuilding industry. VPPA hasbeen used for joining thick-section aluminum inrocket boosters and casings with high qualitywelds. This approach may show application foraluminum platework in the shipyards. Accuratefit-up is required for this application.

STATE OF RELATED INDUSTRY:PAW has primarily been applied in the aerospace

and household appliance industries, as well assome automotive applications. The process haslent itself to high production automation systemsin these industries.

ENABLING TECHNOLOGIES:PAW has proven to be very robust for high

volume automation welding operations due to itsrecessed tungsten electrode, which provides longeroperating times. The directionality of the arc andits relative insensitivity to torch standoff enablesit to achieve high weld quality and fast weldingspeeds.

MANUFACTURING STRATEGIES:Unlike related industries, PAW has yet to draw

support in the shipbuilding industry. Thisresistance may be due to the process’ lack offlexibility compared to GTAW, and to the shipyards’lower volume of similar components. PAW is notreadily available in the typical forms ofmechanization and automation as used by theshipyards.

Brazing

INTRODUCTION:Brazing is a process that produces coalescence of

materials by heating them to the brazing temperaturein the presence of a filler metal having a liquidusabove 840°F (450°C) and below the solidus of the basemetal. This process differs from other joining methodsin that the brazing does not melt the base metalsbeing joined, thereby allowing dissimilar or difficult-to-weld materials to be joined.

STATE OF THE INDUSTRY:Brazing is primarily used in the U.S. shipbuilding

industry to fabricate copper and copper alloy pipingon-board ship for plumbing or heating/air conditioninginstallations. Additionally, the process is used to joinalmost all of the traditional materials used for shippiping. The most common method of brazing joints isthe oxy-fuel torch process. Usually manipulated byhand, the parts are heated to the proper temperatureso that the brazing material will flow between twosurfaces to complete the joint. Brazing in shipapplications differs from that of the automotiveindustry in that the latter uses this process for thefairing of surfaces.

STATE OF THE ART:The state of the art involves the brazing materials

and techniques being used and developed in theaerospace industry for very critical applications.

STATE OF RELATED INDUSTRY:In some related industries, brazing is automated

and may use induction heat or infrared sources.These applications are typically small in size andhave a large family of similar parts. One of thelargest, single industrial applications of brazing isthe joining of copper piping in commercial applicationssuch as heating and air conditioning equipment. Likemost of the welding processes, the ASME Boiler andPressure Vessel Code recognizes brazing as a viable

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method for joining certain piping and pressure vesselcomponents of high pressure service.

Another significant usage of brazing is the joiningof dissimilar metals; metals to nonmetals; or metalsand metal combinations that do not lend themselvesto welding with conventional methods. The jet engineindustry relies on this capability of brazing to joincritical components; however, most of its brazing isdone in a furnace or under more controlled conditionsthan is possible with standard torch brazing.

ENABLING TECHNOLOGIES:Enabling technologies would involve those which

lead to improvements in consumables or equipment.

MANUFACTURING STRATEGIES:Because of the unique design of braze joints, greater

use of this process would require redesign ofcomponents.

Laser Welding

INTRODUCTION:Laser welding (LW) is a process that produces

coalescence of materials with the heat obtained fromthe application of a concentrated coherent light beamimpinging on the joint. This process can be performedautogenously or through the use of filler metaladditions in the form of wires, preforms, or metalpowders. Filler may be used to modify the metallurgyor to aid in bridging gaps caused by poor fit-up.Depending on beam power and quality, weldpenetrations over one inch may be obtained. The highspeed, low heat input, and precision of LW results inlow thermal distortion.

Many different materials can be laser welded,including materials and combinations that areconsidered only marginally weldable with conventionalarc processes. With the advent of using fiber optics totransport the light beam to the work, rather thanhaving the part move under the beam, possibleapplications for LW include in-situ repair work, beamto plate joints, and pipe welding. Over the nextseveral years, the use of LW is expected to increase inship construction.

STATE OF THE INDUSTRY:LW has seen only limited applications in U.S.

shipyards. While construction costs are a majordriving factor in using manufacturing methods, LWhas lagged in application because of its high cost ofequipment and lack of accepted qualification standards.

Recently, however, LW was used to fabricate teestiffeners for the fabrication of corvettes. Additionally,laser welded angles, tees, and cruciform sections wereused in DDG HEPA filter arrays. Laser-welded,corrugated-core sandwich panels have also beeninstalled as antenna platforms on the U.S.S. Mt.Whitney. The panels are being evaluated in this pilotproject as a possible lightweight replacement fortraditional, beam-stiffened plate designs for bulkheads,decks, and doors.

In Europe, the use of laser welded structuralelements and sandwich panels is also increasing.Currently, two European shipyards (Meyer-Werfftand Fincanteri) have implemented LW into theirproduction. Odense (OSS) has attained ABSqualification for hull welds in steel, and has recentlystarted production welding as well. A major laserinstallation is scheduled to go into production atBlohm & Voss early in 2000. The Japanese WeldingResearch Institute is also evaluating the use of LWfor aluminum ferry decking.

STATE OF THE ART:High speed and controlled heat input, combined

with the ease of automation, make LW an excellentchoice for precision manufacturing applications.Refractory alloys are laser welded for high temperatureaerospace and satellite applications, and transmissioncomponents are laser welded at high production rateswith high reliability. Medical devices, electronicpackages, and automobile air bag housings are lasersealed without heat effects to the internal components.Laser-deposited cladding provides a metallurgicalbond with minimum dilution and superior propertiesin the clad materials.

STATE OF RELATED INDUSTRY:Traditional heavy fabrication industries have not

yet adopted LW on a wide scale. However, someindustrial applications which reflect the highproduction requirements of long welds (typical ofshipyards) do exist.

• As part of the production process for buildingrailroad locomotives, GE Transportation Systemsregularly laser welds components up to 0.750inch in production.

• The automotive industry fabricates tailoredblanks, where sheets of dissimilar composition,coating, or thickness are combined into a singleblank for stamping into door panels and otherautomotive components.

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• Japanese manufacturers have qualified LW forproduction of structural members (e.g., tees, boxbeams, tubing) as well as the production ofstainless steel piping for sour gas service.

• A Japanese steel company is using LW to joinone-foot plates. This application requirespreheating of the plate.

ENABLING TECHNOLOGIES:Continued successful implementation of LW in

European shipyards, as well as routine acceptance byship classification societies, will help reduce barriersin U.S. shipyards. However, some factors remain tobe addressed before U.S. implementation iswidespread:

• Pre-Processing — Accurate joint fit-up is criticalto successful LW. Ship classification societieshave established that shipbuilders mustdemonstrate their ability to produce weldpreparations precisely and repeatably inproduction as a criterion in LW processqualification. Considerations must be made forthe edge alignment, the fit-up tolerances, and theexpected lower travel speeds to determine theefficiency of this process for ship panel fabrication.Current implementations of heavy-section LWinclude milling of the steel plates to achieverequired tolerances. Specifications for incomingmaterial fairness/flatness must also be tightened,and steel chemistry requirements may also needmodification.

• Process Modification — In high yield steels,special filler wires or other techniques may beneeded to meet stringent U.S. Navy andcommercial toughness requirements.

• Power Level — High power CO2 lasers are thedominant lasers for heavy-section applicationsdue to the higher power levels available. Nd:YAGlasers can deliver a beam through flexible fiberoptic cables which aids in automation, but powerlevels and beam quality have not been sufficientfor most anticipated applications. The advent ofhigher power Nd:YAG lasers with improved beamquality (four-kW and five-kW models are becomingavailable) will greatly enable the automatedapplication of LW on a large scale, and in almostany area of the vessel for fabrication and repair.Advancements in the power-level technology arealso being driven by needs in other industries.Improvements are expected to be forthcoming.

• Design for Manufacturing — Critical to theultimate success of LW are optimal joint designs;

design for beam access and processing; andintegration of LW with material handling andother shipyard processes. Additionally, a catalogof standardized joints and components will helpreduce the amount of system programmingrequired. These elements need to be incorporatedinto the shipyard’s designs, product models,process planning, and electronic resourceplanning/manufacturing resource planning.Presently, the supporting data, requirements,and implementation technologies are not available.

MANUFACTURING STRATEGIES:The speed, quality, accuracy, and minimal distortion

provided by LW make it extremely appealing forshipbuilding applications. Increases in processingrate and the ripple effects in improved productivity indownstream assembly processes could justify thecapital investment required for implementation, andprovide a significant competitive advantage inworldwide markets.

Electron Beam Welding

INTRODUCTION:Electron beam welding (EBW) is a process that

produces coalescence of metals with the heat obtainedfrom a concentrated beam composed primarily of highvelocity electrons impinging on the joint. Initiallyused as a commercial welding process in the late1950s, the process was quickly recognized as a methodfor making high quality, deep penetrating welds oncritical parts.

EBW features three basic methods: high vacuum;medium vacuum; and non-vacuum (EB-NV). Themajor difference among them are the achievable weldbead shape. Due to the large components required forship construction, EB-NV is the most practical in theshipbuilding industry. The required vacuum chambersize for the vacuum EBW methods are extremelyexpensive and time consuming due to the pump-downcycle. Although the vacuum chamber is not requiredfor EB-NV, some type of radiation shielding must stillbe provided to protect personnel from the x-raysgenerated.

STATE OF THE INDUSTRY:Currently in the shipbuilding industry, EBW is

only being used on selected, high-integrity pressurevessel welds in ship propulsion systems.

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STATE OF THE ART:Continuous improvements in EB-NV gun designs

and process controls, coupled with recent developmentsin nozzle design techniques, have greatly increasedthe EB-NV system’s stability and reliability. Narrow,low distortion welds formerly considered to be weldableonly in a vacuum are now within the capability of EB-NV. The use of helium as a shielding gas reduces thelocal atmosphere density, resulting in less beamdispersion or spread. Deeper penetration and highertravel speeds can also result from the use of helium.

STATE OF RELATED INDUSTRY:EB-NV is used in the pressure vessel industry for

thick-section welding, and is continuing to gainacceptance in the high production automotiveindustry. Aluminum intake manifolds, transmissioncarrier assemblies, and torque converters have allbenefitted from EB-NV.

ENABLING TECHNOLOGIES:Nozzle developments for the vacuum-to-atmosphere

orificing have greatly increased the EB-NV system’sstability and reliability. A minor modification to theorifice system, which permits the use of helium, hassubstantially increased the beam throw (the ability toweld at greater work distances). A new, narrower,deeper penetrating weld has also become the EB-NVstandard.

MANUFACTURING STRATEGIES:Substantial rewards may be achieved through

further investment in the EB-NV process for caseswhere narrow, deep penetrating, low distortion weldsare required. Non-vacuum air welds provide a decreasein transverse shrinkage compared to arc welds, andthe use of helium gas shielding decreases thetransverse shrinkage even further. Implementationof EBW in general shipbuilding is foreseen as beinglimited to a small suite of applications where weldquality and integrity is critical, or in applicationswhere extremely thick-sections are to be joined.

Friction Stir Welding

INTRODUCTION:Friction stir welding (FSW) is a solid-state process

that produces coalescence of materials under thecompressive contact force of a rotating tool and thework pieces, moving relative to one another to produceheat and plastically displace material from the fayingsurfaces. The solid-state low distortion welds are

achieved with simple, energy-efficient mechanizedequipment. This low-cost process enables butt andlap joints to be made in low melting point materials(e.g., aluminum alloys) without the use of fillermetals.

FSW joins materials by plasticizing and thenconsolidating the material around the joint line.First, a hole is pierced at the start of the joint with arotating steel pin. The pin continues rotating andmoves forward in the direction of welding. As the pinproceeds, the friction heats the surrounding materialand rapidly produces a plasticized zone around thepin. Pressure provided by the pin forces plasticizedmaterial to the rear of the pin, where it consolidatesand cools to form a bond.

STATE OF THE INDUSTRY:FSW was developed for the European market,

specifically for high-speed aluminum ferries wherecorrugated aluminum extrusion are joinedlongitudinally to fabricate automobile deck structures.Although development work for steel applications iscurrently ongoing, the technology requires furtheradvancements before FSW because useful in theseshipyard applications. Presently, more than 30,000meters of weld have been produced in aluminum panelstructures without a defect.

STATE OF THE ART:FSW’s most sophisticated application is in the

fabrication of Delta-family rocket boosters. The FSWprocess has replaced the arc welding of longitudinalwelds on the Delta II booster, and will be used toproduce the new Delta IV evolved expendable launchvehicle. The first FSW booster was launched inAugust 1999. Aerospace manufacturers are currentlyexploring FSW of aluminum for primary aircraftstructure and higher-performance materials in aircraftand aircraft engine applications.

STATE OF RELATED INDUSTRY:The automotive and heavy manufacturing industries

are beginning to explore FSW in both aluminum andsteel applications, but technology has yet to beimplemented.

ENABLING TECHNOLOGIES:New developments that would enhance the use of

FSW include:• Technology to produce welds in curvilinear paths.• Technology for thicker-section (over one inch)

aluminum welding.

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• Technology for higher performance materialssuch as higher performance tools and higherprocessing loads.

• Process data to qualify FSW for ABS and U.S.Navy acceptance.

• Process models to predict weld performance andspecify process parameters.

MANUFACTURING STRATEGIES:FSW’s ability to produce long, linear solid-state

welds in plate materials provides a range ofopportunities in shipbuilding. One benefit of thisprocess is its ability to make seam welds on aluminumalloys that cannot readily be fusion welded withoutover-designing the joint. For age-hardenablealuminum alloys, joint efficiencies of 90% can heachieved. In comparison, the best available weldingtechnologies can only achieve joint efficiencies of 50%for these materials.

Preliminary research into applying FSW to steels,stainless steels, and other high-performance alloysindicates that the process may be similarly productiveand less sensitive to base metal composition in steelsas it is in aluminum. In addition, solid-state welds arenot subject to hydrogen contamination whichcontributes to embrittlement and cracking. Therefore,higher-strength steels welding (currently subject tostringent and expensive process qualification andcontrol requirements) could be performed moreefficiently and effectively.

The solid-state bonds are produced at temperaturessignificantly lower than arc welds. Since heat inputsare significantly lower than those of traditional arcwelding processes, thermally-induced distortion(highly problematic in welding thin residual stressand distortion) is reduced or eliminated. No jointpreparation is required, and weld fumes; spatter andhot-cracking; and gas porosity are absent. In additionto minimal loss of base metal mechanical properties,the reduction in corrosion properties is also minimal.As a result, more efficient structures can be designedwhich take advantage of improved weld properties.Fabrication costs can also be significantly reduceddue to the lowered requirements for process controland qualification.

Resistance Welding

INTRODUCTION:Resistance welding (RW) is a process where the

coalescence of metals is produced by the heat generatedby the resistance of the metal to the passage of electric

current. This process is ideal for overlapping sheetmetal connections.

STATE OF THE INDUSTRY:In ship construction, RW is used for ventilation

work, joiner work, and other sheet metal operations.Most of these applications do not challenge the limitsof this technology. For the most part, RW is performedefficiently and effectively.

STATE OF THE ART:The automotive and light manufacturing (e.g.,

appliance) industries are, by far, the leaders in high-production RW. Here, the process is applied to avariety of steels with various coatings to produce awide range of simple and complex components.Sophisticated feedback control systems allow thewelding of multiple sheet stack-ups. Automated weldcells can produce more than 100 spot welds in a singleweld cycle.

STATE OF RELATED INDUSTRY:Off-highway equipment manufacturers and

fabricators apply RW to a similar class of sheet metalapplications, in much the same manner asshipbuilders.

ENABLING TECHNOLOGIES:The state of the art of RW equipment is sufficient for

current shipyard applications.

MANUFACTURING STRATEGIES:RW will continue to be applied in shipyard sheet

metal applications.

Thermal Spraying

INTRODUCTION:Thermal spraying is a process in which finely divided

metallic or nonmetallic surfacing materials are depositedin a molten or semi-molten condition on a substrate toform a spray deposit. The three most commonly usedmethods are electric arc spraying (EAS); high velocityoxy-fuel (HVOF) spraying; and atmospheric plasmaspraying (APS).

EAS uses a wire consumable, and can spray anymaterial which can be fabricated into a wire, includingsolid, metal-cored, or flux-cored wires. Consequently,wear or corrosion coatings can be produced, and theparts can be rebuilt with a wide range of alloys. EAS ischaracterized by coating porosity levels in the 5% to10% range with fairly low bond strength between thecoating and the substrate (typically two to seven ksi).

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HVOF uses a powder consumable, and can sprayany material which can be produced as a powder.Consequently, wear or corrosion coatings can beproduced, and the parts can be rebuilt with a widerange of alloys. HVOF is characterized by coatingporosity levels in the 1% to 2% range with high bondstrength between the coating and the substrate(typically 10 to 14 ksi).

APS can use either wire and powder consumables.Consequently, wear or corrosion coatings can beproduced, and the parts can be rebuilt with a widerange of alloys. APS is characterized by coatingporosity levels in the 1% to 2% range with intermediatebond strength between the coating and the substrate(typically seven to ten ksi).

STATE OF THE INDUSTRY:Various thermal spray processes are used in ship

applications, typically for corrosion protection ofsteel surfaces and the restoration of machinedsurfaces that may be worn, eroded, or corroded.Although the most common method of application isflame spraying, the shipbuilding industry also usesEAS and HVOF techniques. Another option is APS,but it has a limited extent compared to the otherprocesses. Typical applications in shipbuilding andrepair include pumps, valves, bearings, and shafts inrotating equipment. Coatings deposited includestainless steels and nickel alloys for corrosionprotection, and tungsten carbide cobalt coatings forwear protection.

STATE OF THE ART:State of the art spraying systems include high

energy HVOF systems (typically 200 kW) which canspray high quality coatings at high deposition rates.These systems are often used in applications such ascoating large rolls for papermaking and printingequipment. The latest HVOF equipment is capable ofspraying wires rather than higher cost powders.Developments in HVOF flame technology have alsoincluded liquid fuels (e.g., kerosene). This technologyreduces spraying costs by using kerosene/air mixturesrather than traditional gas/oxygen or kerosene/oxygen mixtures. Also available are higher energyplasma spraying systems, suitable for sprayingmultiple wires simultaneously for high depositionrate coatings. Few developments have occurred inflame spray or arc spray equipment in recent years.

STATE OF RELATED INDUSTRY:In related industry, the most commonly used

thermal spray processes are EAS, HVOF, and APS.

HVOF has a broader use in industry compared toshipbuilding, mainly because a wider range ofapplications, environments, and coatings areavailable. Additionally, high energy HVOF and highenergy APS equipment are extensive used forapplications requiring high deposition rates overlarge areas being coated. EAS is well developed forcorrosion protection of large offshore structures andpipelines in seawater environments with aluminumand aluminum-zinc coatings. Thermal spraying is atechnology which has not been exploited for large-scale protection of ship structures in the shipbuildingindustry. Lifecycle costing for painting versusthermal spraying is an another issue that needs to beexamined.

ENABLING TECHNOLOGIES:For field deployment of thermal sprayed coatings,

a manual spraying technique is usually employed.Low level mechanization can be applied by usingsimple track-mounted spraying heads. Mechanizationand automation are more common in shop-basedspraying operations, often within a spray booth.Typical equipment include single axis track-mountedsystems; X-Y coordinate positioning systems; andarticulated arm robots.

MANUFACTURING STRATEGIES:The results achieved through thermal spraying

depend heavily on the quality and cleanliness of thesurface preparation performed on the substratematerial or part to be sprayed. The stripping of oldcoatings or removal of corrosion products prior tosurface preparation by grit blasting is important toensure the quality of the resultant coating, particularlyto the adhesive bond strength between the coatingand the substrate. An effective alternative techniqueis to use a bond coat, typically Ni-Al in the form of anarc-sprayed or flame-sprayed wire. The requiredcoating can then be applied directly to the bond coat.

Polymer Joining

INTRODUCTION:Polymer joining is a variety of processes used to

join polymer materials such as plastics andcomposites. The processes include adhesives; hotplate; hot gas; resistive and induction implant welding;friction welding; and laser and infrared welding. Theselection of method is dependent on the polymerchemistry, the joint designs, and the servicerequirements.

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Welding and joining processes can replicate basemetal strength in joints. The alternative is mechanicalfastening which means the joints must be over-engineered to accommodate the fastener holes.

STATE OF THE INDUSTRY:With the advent of newer ship designs implementing

polymers (e.g., plastic pipe, tankage), technologiesfor joining these materials are now being introducedinto shipyards. Fiberglass boat builders successfullyapply a variety of processes during ship fabrication.Some of these approaches have been employed fornonmetallic structures on U.S. Navy minesweepers.

STATE OF THE ART:The automotive and light manufacturing industries

perform millions of plastic welds each year usingvarious processes. Much of the low-pressure, naturalgas transmission lines in residential neighborhoodsare PVC piping, which is routinely welded and adhesivebonded. The aerospace industry has developedworkable approaches for joining high-performance,polymer-matrix composites to avoid the use onmechanical fasteners, which degrades jointperformance.

STATE OF RELATED INDUSTRY:Polymer joining has limited use in the heavy

fabrication industries.

ENABLING TECHNOLOGIES:As polymer-matrix composite materials are

implemented into ship structures, low-cost efficientjoining processes for these materials will need to bedeveloped. Among them are processes for polymer-to-metal joining to assist in the implementation ofpolymers in shipbuilding; using composite materialsas a viable alternative for patching and repairingsteel structures; and non-destructive evaluationtechniques for polymer bonds. Additionally, eachprocess would need to be able to withstand the ruggedenvironments of the shipyard for manufacture andon-board ship for repair issues.

MANUFACTURING STRATEGIES:Plastics joining techniques will follow the

implementation of polymers into ship designs.Advantages include low weight, superior corrosionperformance, dimensional stability, and minimalmagnetic signature.

Robotics

INTRODUCTION:Robotics is the technology dealing with the design,

construction, and operation of robots in automation.A robot is an automatically controlled,reprogrammable, multi-purpose manipulator thatoperates in three or more axes, and performs definedtasks within its working envelope. Design forautomation and continuous improvement in roboticsare helping to enhance and foster this technology inmany industries.

Robotics were initially used to move packages fromone location to another. Since a robot could hold amaterial gripping tool, reasoning followed that itcould also hold a welding or cutting torch. From thisstart, the use of robots for cutting and welding hasspread virtually throughout all industries. However,the introduction of welding robots into shipyards hasbeen at a slower pace. The accuracy of early robotswas sufficient for resistance spot welding, butinadequate for the quality needed in arc welding.Today, the applications for welding robots are growingin the U.S. shipbuilding industry with improvementsin software and hardware of robotic systems.Improvements in off-line programming, sensingtechnology, and mechanical system design have allcontributed to the recent introduction of robots intothe U.S. shipyards.

STATE OF THE INDUSTRY:Robots are now used for welding small piece parts

such as pipe hangers, tie-down fittings, ladders, andscuttles. These high volume parts are excellentcandidates for robotic work. Other systems are nowbeing used to make structural plate parts that requiremore advanced programming technology.

In other parts of the world, shipyards are usingwelding robots more extensively than in the U.S.shipyards. Many of these shipyards have greatlyendorsed the concept of robots for large panelapplications, while others have eschewed the practicealmost entirely. To date, the major applications havebeen in profile cutting and marking; panel lines (e.g.,large, micro, curved panels);and egg-crate weldingoperations. Some shipbuilders have found success inthe implementation of portable robotic systems formany subassemblies. In these cases, theimplementation was developed in the context of aspecific product line with a dedicated processing planand a facility tailored to the application. Currently,portable robotic systems do not appear to offer a

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solution for in-place replacement of individual weldersin most applications.

Many U.S. shipyards have not invested in theaccuracy control requirements necessary for roboticwelding. The tolerances on as-purchased mill rolledshapes are not sufficient for robotic welding withoutthe addition of advanced sensors and tracking systems.Adopting the extra process control technologysignificantly increases the cost and effort required forrobot implementation. For cutting applications, manyU.S. shipyards have followed the lead of the Europeanshipyards, and now use robots to cut the variousstructural profiles required for ship construction.

STATE OF THE ART:The largest market for welding robots is in the

automotive industry. Much publicity has documentedthis industry’s use of robots for resistance weldingapplications. Arc welding robots are also usedextensively in the fabrication of automotive frames,car seats, and other components. Robotic andautomated processes are the preferred method ofassembly at the prime and sub-tier supplier levels.Design for automation has been incorporated intothe product development process. A robust supplierbase of robot manufacturers and tooling designersexist to support these efforts.

STATE OF RELATED INDUSTRY:Related heavy manufacturing industries (e.g.,

construction equipment and farm implementcompanies) have been using some level of roboticsfor welding since the 1970s. Although they aretaking advantage of the continuous progression ofrobotic hardware and software improvements, thesecompanies have invested in technologies that bringaccuracy control requirements to their parts whichare necessary for robotic welding.

ENABLING TECHNOLOGIES:Continuous improvements in robotic software

and hardware are playing a role in bringing thistechnology to the shipyards. Further developmentsare required in off-line programming, sensingtechnologies, planning systems, and the integrationof welding/cutting process knowledge into the CADpart information or within some level of planning/management software. A continuous emphasisneeds to be placed on construction design formanufacturability with automation.

MANUFACTURING STRATEGIES:The use of robotics for cutting and welding will

facilitate the drive toward JIT and CFM stylematerial flow from raw materials to final assembly.Reduction and elimination of non-value added tasksshould reduce cost and delivery. Full scalerobotization of welding and its allied processes inany shipyard in the world is still some time away.The robot is only one element in the implementationof CIM into shipbuilding. Successfulimplementation of robotics has incorporatedintegration of the robotic software with shipyards’CAD and materials planning systems. Some ofthese systems required large investments in thematerial preparation of plates, profiles, and/ormanufacture of subassemblies.

Automation

INTRODUCTION:Automation is the technique of making an

apparatus, a process, or a system operate by a self-regulating mechanism. Typical examples of single-purpose mechanized automation include portabletractors, fixed dedicated systems, sensor technologies,and small computer-based processors.

STATE OF THE INDUSTRY:Single-purpose mechanized automation for welding

and cutting operations is well established in theshipbuilding industry. Many of the fixed dedicatedsystems require minimal operator intervention duringtheir execution. On the other hand, portable systemsmust be set up and torn down by the operator, andrequire repositioning and parameter adjustmentsduring their operation. The selection of equipment isdependent on the welding or cutting process beingemployed, and the flexibility or motion required tocomplete the task. Newer forms of automation (e.g.,those used to locate, tack, and weld stiffeners topanels) are more common in European shipyardsthan U.S. shipyards.

STATE OF THE ART:Currently, a new generation of portable mechanized

automation is appearing in the market. These systemsare referred to as smart mechanization. In essence,they are two- to four-degrees of freedom systemswhich are controlled by small computer-basedprocessors using servo or stepper motor technology.The smart mechanization systems can use availablesensor technologies and programming to work

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autonomously, after being placed in the global vicinityof the path to be followed for a particular process.With this capability, multiple systems can be set upand used by one operator.

STATE OF RELATED INDUSTRY:Related industries’ applications for automation are

similar to those of the shipbuilding industry. Amongthese are structural fabrications for buildings, plants,highways, and construction equipment manufacturing.Shipyards have provided much effort in improvingportable pieces of equipment to facilitate ease ofportability, minimize set up/tear down, and improverobustness of components to make them moreaccommodating to production applications.

ENABLING TECHNOLOGIES:The use of sensor technologies and onboard

computer controls allow the smart mechanizationsystems to run autonomously or quasi-autonomously,rather than requiring operator intervention. Thesesystems can control their position, and adaptivelycontrol the process if the proper sensor technologiesare applied.

MANUFACTURING STRATEGIES:Smart mechanization automation enables one

operator to direct multiple systems. This approachshould increase the productivity achieved per laborhour in production. As technologies advance, theproductivity per unit labor hour should also increase.

Non-Destructive Testing

INTRODUCTION:Non-destructive testing (NDT) refers to the

inspection, analysis, or treatment of material withoutdamaging or altering its initial state. Typical methodsinclude surface examination, volumetric examination,radiographic testing, and ultrasonic testing.

All of the shipbuilding regulatory bodies requiresome amount of NDT for welds. Depending on theapplication and criticality of the weld joint, theinspection may involve surface examinations (e.g.,visual, penetrant, magnetic particle) or throughthickness volumetric examinations. Eddy current(electromagnetic) methods can be used for a varietyof examinations including paint thickness gauging.However, this technique usually involves theevaluation of components, such as heat exchangertubes, for service-related degradation.

Among the volumetric NDE methods applied forshipbuilding applications are radiographic andultrasonic testing. Both methods can detect surfaceand subsurface discontinuities, but are primarilyused to detect subsurface conditions. The volumetricinspection technologies are also being transformedby newer developments in automation,computerization, and electronic componentadvancements. Recent developments include systemsthat can store radiographs on computer discs, andultrasonic inspection signals which can be reportedin three dimensions using computer assistance.

STATE OF THE INDUSTRY:Virtually all of the available NDE methods are used

to some degree in the U.S. shipbuilding industry,primarily due to the requirements imposed by variousregulatory bodies. Visual examination, the primaryinspection method, is supplemented by other surfaceand volumetric methods where designs or standardsdictate the need for more extensive evaluation.

Radiographic testing, typically employed using aradioactive isotope as the radiation source, is themost common method for volumetric examination.However, the use of ultrasonic testing is increasingsince it can be applied more expediently; at a lowercost; and without the need for evacuation of thetesting vicinity due to the inherent radiation hazardof radiography. Ultrasonic testing, in lieu ofradiography, is of particular interest for applicationssuch as submarine hulls, where the wall thicknessesdictate long radiographic exposures. The ultrasonictechnique is typically applied manually, but newdevelopments in equipment with computerizedenhancements are leading to mechanized applicationson a limited basis. The U.S. Navy is currentlydeveloping a knowledge-based inspection system thatcombines a mechanized scanner with a neural network.Not only does this arrangement detect discontinuities,but it also detects sizing and characterization toprovide decision-making intelligence.

One area of interest to shipyards is the developmentof EMATS for surface and volumetric inspections.This method uses electromagnetic energy to generateultrasonic waves in the test object. One majoradvantage is that the transducer need not contact thepart, as is typically the case for standard ultrasonictechniques. Recent developments have alsodemonstrated this inspection method as useful forautomated inspection of welds immediately followingthe welding torch.

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STATE OF THE ART:The development and application of NDE for post-

fabrication quality verification are relatively advancedin all industries including shipbuilding. Additionally,technological advancements are being focused in theareas of:

• Increased mechanization/automation.• Sensor application to monitor fabrication

operations such as welding on a real-time basis.• Greater computerization including the creation

of systems integrating artificial intelligence.• Development of techniques and systems for

examining components on-line.• Development of systems capable of providing

global monitoring of components as opposed tomore typical localized examinations.

STATE OF RELATED INDUSTRY:The state of NDE in related industry is not

substantially different than those of the shipbuildingindustry. For applications or industry sectors whichrequire very stringent evaluation, more specializedmethods or enhancements are being applied to existingmethods; however, if similar design or performanceconstraints exist in the shipbuilding industry, thenthose same techniques are quickly adopted and applied.In cases such as inspection of nuclear components forU.S. Navy vessels, the development of NDEtechnologies by the shipbuilding sector have precededother industries.

ENABLING TECHNOLOGIES:Enabling technologies are mainly related to

improvements in the areas of automation andcomputerization. Like welding, an interest exists fordeveloping NDE techniques that essentially eliminatethe inaccuracies introduced by human error.

Therefore, systems must be developed thatsynergistically provide information related todiscontinuity type, size, and location. Additionally,sophisticated electromechanical systems are requiredwhich incorporate the necessary computationalabilities to improve on human capabilities.

MANUFACTURING STRATEGIES:The advancement and application of NDE has an

indirect effect on manufacturing strategies. The simpleapplication of NDE does not improve a manufacturingprocess nor does it provide a more defect-free,performance-enhanced component. However,improvements in NDE techniques could allow for amore reliable detection of critical flaws, which couldeventually lead to relaxation of quality requirementsbecause inherent conservatism is no longer required.Furthermore, the advancement of sensors and relatedfeedback systems employed during welding operationsmay foster advancement from the defect detectionmode into the realm of defect prevention (e.g.,monitoring the process in real-time and adjusting itto prevent the occurrence of defects).

POINTS OF CONTACT:For further information on SP-7 Panel items in this

report, please contact:

Mr. Lee KvidahlIngalls Shipbuilding(228) [email protected]

Mr. Matthew WhiteNavy Joining CenterEdison Welding Institute(614) [email protected]

CHAPTER SUMMARY:Surface preparation and coating activities in U.S.

shipyards continue to be challenged by a variety ofissues. Perhaps the greatest impact has been throughconstraints imposed by federal and stateenvironmental regulations. The challenge ofcompliance has been and continues to be an ongoingexercise of transitions for most shipyards. Althoughtypically arduous to the bottom line, these transitionshave sometimes resulted in process improvementsthat provide a healthy return on capital expenditures,such as plural component spray equipment and powdercoating lines. Other constraints include the inherentparameters of local climatic conditions and the impactof other trade activities on the surface preparationand coating processes.

Although surface preparation and coating of shipsis a broad and highly technical field, it has yet toachieve the same level of attention as other shipyardactivities relative to improving efficiency. The costfor repair and maintenance of existing coating systemshas caused many ship owners to specify improvedcorrosion control systems that achieve longer lifecycles. The result is an increased quality expectationby the customer which drives the industry to a higherlevel of sophistication in terms of coating materialsand application processes. To remain competitive,shipyards must embrace the evolving surfacepreparation and coating technologies as they improvetheir other fabrication and repair processes.

The SOA report identifies process areas and buildsstrategies and technologies for surface preparationand coatings that have a positive impact on theoverall shipbuilding process. Equally important tothe continuous stimulation, development, andimplementation of new technologies is the need toexplore the efficiencies of current paint shop processes.Metrics of performance have also been identified as abaseline for measuring the efficiency of currentpreparation and coating processes. To assess thebenefits of new technologies or compare U.S. shipyardsto foreign competition, it is necessary to improve thebenchmarking capabilities within shipyard paintshops.

The surface preparation and coating processesdescribed in this report represent areas of opportunityfor enhanced competitiveness and profitability. Thereport discusses nine discrete processes with emphasis

on the interrelationships among themselves and othershipyard processes. Some of the process categoriesprovide a response to regulatory parameters andcustomer demands, while others address newtechnologies in shipbuilding and the often overlookedinefficiencies of basic processes. In fulfilling its missionwithin the MARITECH ASE NSRP, the SP-3 Panelwill prioritize and commit further resources to theexploration and definition of these process categories.The resulting efforts will be used to identify state-of-the-art best manufacturing practices and torecommend future investments in shipyard surfacepreparation and coating processes.

Sequencing and Integration

INTRODUCTION:The sequencing and integration of surface

preparation and coating processes are criticalcomponents of the pre-construction planning functionand build strategy. Each stage of construction iscarefully assessed and placed in balance with theproduct’s coating specifications. Since shipbuildingis an orchestration of multiple trade disciplines, theseprocesses must also be properly blended into theoverall scheme to optimize preservation systemperformance and cost efficiency.

STATE OF THE INDUSTRY:Most shipyards have dedicated planning

departments that create and maintain detailedschedules of work. To produce an optimum workschedule or plan, careful consideration is given toeach trade task and how it integrates with other tradetasks. Typical new construction planning objectivesinclude maximizing surface preparations and coatingapplications early in the manufacturing process. Theactual plan or build strategy, relative to maximumcoating applications, must be balanced against theconstraints associated with the specific coatings beingapplied (e.g., coatings maximum re-coat interval).Additional considerations that influence the overallintegration and sequencing of coatings into the buildstrategy include:

• Cost per unit surface area at various points in themanufacturing process.

• Anticipation of hot work or other damages tocoatings applied early in construction.

S e c t i o n 4

Surface Preparation & Coating Technologies (SP-3 Panel)

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• Accessibility to surfaces requiring coating late inconstruction.

• Process impact on other trades.• Facility limitations.• Environmental compliance.The ultimate goal for surface preparation and

coating sequence and integration is to eliminate non-value added labor and rework occurrences.

STATE OF THE ART:Planning efforts differ in approach and philosophy

from one shipyard to the next. Regardless, shipbuilderscontinue to explore, develop, and utilize computertechnologies to assist in the planning effort. Lineitem tasks or events are defined, stored, and eventuallyretrieved for integration into a construction plan.Sequencing of events is generally based on deckplatelogic. The greatest attribute associated with computeraided planning is the timely ability to input, retrieve,and sort events relative to the applied logic.

STATE OF RELATED INDUSTRY:Large commercial construction projects depend on

effective sequencing and integration of events toachieve profitability. As in shipbuilding, limitationsand constraints must be defined to effectivelycoordinate and schedule multiple trade events.Avoidance of rework, delays, and disruptionsassociated with subcontract work are commonobjectives that are addressed when developing aconstruction plan. Computer technology is alsoutilized in support of non-shipbuilding commercialconstruction.

ENABLING TECHNOLOGIES:The evolution of computer technology continues to

provide business solutions for all aspects ofmanufacturing. Versatile programming capabilitiesallow end users to achieve timely assessments ofscheduling options relative to sequencing andintegration of events. In the absence of deckplateexperience, crucial historical data can be readilypreserved for future planning efforts.

MANUFACTURING STRATEGIES:Computer technology will not entirely replace the

deckplate experience necessary to incorporate properlogic into a plan. However, technology does exist fordeveloping models and programs that work inharmony with historical data to produce a buildstrategy influenced by practical shipbuilding logic. Of

significant value to the shipbuilder is the ability topredict the costs associated with the integration of anevent at any point in the manufacturing process.Process models, populated with historical performancedata specific to a stage of manufacturing, can bedrawn on to provide a cost analysis of an event at theprecise point of schedule integration. Differentscenarios can be explored to determine optimumsequencing and integration points based on economicsrather than speculative experience.

Surface Preparation and Coating ProcessControl

INTRODUCTION:Surface preparation and coating process control is

a management activity that monitors performance tobudget, relative to progress. Using this process, paintdepartment managers can perform an analyticalassessment of productivity on discrete work orders orlabor charges.

STATE OF THE INDUSTRY:The format of surface preparation and coating

process control varies from shipyard to shipyard.Typically, the paint department is provided with abudget for a specific project based on historicalperformance to a comparable scope of work. Budgetedlabor hour allocations also vary relative to allowances(e.g., discreet process functions; work order package).As work progresses to the scope of work defined,periodic reports account for labor hour expenditures.Progress is generally measured in terms of percentageof workscope completed, which is then compared toactual labor hour expenditures to gauge performance.Since assessment is commonly based on the humanelement, the measurement of progress is oftensubjective. This subjectivity, however, is minimizedby incorporating an increased level of detailed processprogression values into the budgeted scope of work.The ability of the paint department manager toelectronically collect and assess data has also beendramatically improved. Computer aided processcontrol is offering greater opportunity due to theincreased availability throughout the supervisoryranks of manufacturing.

STATE OF THE ART:Although most shipyards have developed a computer

aided systems approach to process control, theseapproaches are as individualized as the shipyards.The formats and programs suited to managing surface

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preparation and coating process data, however, arecertainly capable of being developed and integratedwith other shipyard systems. Paint departmentmanagers or supervisors could also electronicallyaccess time accounting data in a standard shipyardformat. The stumbling block is trying to configurethe data in order to measure performance and managethe process.

Surface preparation and coating activities inshipyards involve a large number of discreet processesworthy of analytical definition. Based on surveys ofNSRP participating shipyards, a need exists to captureproductivity values to a more discreet level. There isalso a desire to develop a program capable ofintegrating actual labor hour expenditures so as toproduce an accurate analysis of discreet processcosts and rates. Such an capability would allowmanagers to compare real-time productivity tobaseline process rates as a measure of performance,and assess the cause and effect of process changes ina timely manner. Beyond the inherent value as adaily management tool, strategic planning modelscould be developed to take advantage of process costand rate data to estimate costs for proposed newwork.

STATE OF RELATED INDUSTRY:For this area, further evaluation and collaboration is

underway.

ENABLING TECHNOLOGIES:The SP-3 Panel sponsored four NSRP projects related

to capturing and utilizing shipyard surface preparationand coating costs:

• Economics of Shipyard Painting Phase I: NSRPReport #0227

• Economics of Shipyard Painting Phase II: NSRPReport #0302

• Economics of Shipyard Painting Phase III: NSRPReport #0316

• Surface Preparation and Coating Bid EstimatingTransfer Study: NSRP Report #0403

The initial project was based on the need to capturediscreet surface preparation and coating costs by process,and to format a database program to create accurate andreliable bid estimates. During the execution of Phases I andII, it became apparent that a number of non-paint shopmanufacturing activities caused variances in productivity.Phase III then focused on identifying and capturing thosevariances (e.g., lost time due to an inability to start a jobassignment; rework due to incomplete or poor quality

trade work). An ability to capture this information andassess performance to baseline costs/rates was deemed tobe critical to the timely identification of productioninefficiencies. Too often, the cost impact of thesevariances were overlooked because of theirconsolidation within standard cost collection lineitems. The final project in the series examined thedegree to which technology could be transferred toother shipyards. With the exception of softwaredifferences, these transfers were successful.

MANUFACTURING STRATEGIES:Timely availability of cost and progress information

has driven shipyards to provide database accessibilityto their first line supervisors of surface preparationand coating processes. To be efficient, this approachmust be able to identify cost variances from a baselineearly enough to prevent a negative impact to cost, aswell as conduct timely analyses of process changes totake advantage of implementing improvements. Theresearch conducted by the SP-3 Panel has establisheda foundation for shipbuilders to create programs formanaging surface preparation and coating processes.Since the conclusion of this research, computertechnology has advanced to the point where adaptingand building on the findings of the SP-3 projectswould have even greater value than originallyexpected.

Pre-Construction Priming

INTRODUCTION:Pre-construction priming refers to the process by which

ferrous steel plates and shapes, as received from the mill,are preserved prior to fabrication. The primary objectiveof this process is to reduce the cost of secondary surfacepreparations in the later stages of ship construction.

STATE OF THE INDUSTRY:Pre-construction priming of raw steel stock is principally

an automated process. Most new construction shipyardsuse dedicated facilities for removing mill scale and depositingcoatings to protect the steel from corrosion during thefabrication process. The process incorporates a centrifugalabrasive blast cleaning system along with a configurationof automated spray guns for applying primer. Pre-heat andpost-heat ovens accelerate primer dry times, resulting intimely material handling. Conveyor systems allow the rawsteel stock to be transferred throughout the entire process.Pre-construction primer performance, in terms of corrosionprotection longevity, is generally tailored to the durationof a shipyard’s fabrication cycle through structural

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completion of a block assembly. The block assembly is thenprepared and coated using the primary coating systemsspecified by the invoked contract specifications.

The ability to retain the pre-construction primer tothe furthest extent allowed by the specifications isdesirable. Consequently, the integrity and conditionof the primer at the scheduled time of primary coatingsystem application is critical to the minimization ofsecondary surface preparation and resulting costs. Inaddition to the attributes of preservation andretention, the majority of U.S. and foreign shipyardsapply primers with weld-through capabilities as well.Pre-construction primers that meet theserequirements are available in various generic types.Regardless of the primer type but without disregardingthe effects of surface profile after blasting, the mostcritical factor to success is controlling the consistencyand quality of the primer’s dry film thickness. Verylittle tolerance exists between the minimumrequirements for preservation and the maximumcoating thickness that will not impact weld qualityand speed.

STATE OF THE ART:In the last 10 to 15 years, significant advances have

been made in the formulation of pre-constructionprimers due to the productivity and efficiency demandsof shipbuilders. European and Far East shipbuilderswere the first to challenge the coating manufacturersinto developing primers capable of being retainedthroughout a ship with minimal secondary surfacepreparation prior to topcoating with the final paintsystem. In addition, these primers were required tomeet the demands of high speed welding withoutcompromising quality. The technology that emergedfocused on vastly improved solvent-based inorganiczinc paints. Enhancements included improvedcorrosion protection at lower film thicknesses withless zinc; higher welding speeds; higher heatresistance; improved weathering; and greaterversatility for retention in immersion service.Environmental compliance demands have alsospawned water-based inorganic zinc paints and epoxypaints. Each type of primer varies in terms ofperformance relative to the desired attributes.Selection of pre-construction primer thus becomes afunction of a shipyard’s manufacturing strategy andregulatory compliance issues.

Regardless of primer capability, maximum valuecan only be realized if the product is used within itsperformance parameters. Surface preparation istypically accomplished with steel shot or grit. The

abrasive mix is balanced in terms of type, hardness,and particle-size distribution to achieve a near-whitemetal finish with a minimal surface profile. Theresult is optimum coating performance at low dry filmthicknesses. The centrifugal blast equipment is thussized and configured to accomplish the requiredcleaning rates. Configuration and type of the spraysystem is critical to successful primer application.Designs vary relative to target geometries, transferefficiencies, types of primer, production rates, andlevels of automation. Steel plates allow for simpleapplication system solutions, whereas structuralshapes are more challenging due to variances inspray nozzle distance and angle of attack relative tothe target surface geometry. All of the systems functionwithin a balance of constraints dictated by line speed.

STATE OF RELATED INDUSTRY:Pre-construction priming lines require significant

capital to install and maintain. Consequently,fabricators of heavy steel products will typicallyprocure the steel pre-primed. Most steel producershave access to priming lines whereby they can prepareand prime the steel to meet customer specifications.Such specifications can vary significantly in terms ofperformance expectations. A non-shipbuildingcustomer may place more emphasis on corrosionprotection than on weldability, thus dictating thetype of primer and level of application tolerance.Except for configuration differences, the basicprocesses of centrifugal blast cleaning and automatedspray application are similar to those used inshipbuilding.

ENABLING TECHNOLOGIES:De-scaling technology has not significantly changed

in recent years. Centrifugal blast equipment pairedwith recyclable steel abrasives continues to be theoptimum surface cleaning methodology. Primerapplication systems have been enhanced throughcomputer integrated controls. Spray systems can beprogrammed to electronically acquire target surfaces;adjust to specific angles and heights; and, trigger onand off to produce greater application control. Existingpre-construction primer formulations offer theshipbuilder ample opportunity to reducemanufacturing costs if applied in accordance with thecoating manufacturer’s parameters.

MANUFACTURING STRATEGIES:De-scaling (surface preparation) and primer

application processes must be tuned to achieve

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optimum primer longevity at the lowest dry filmthickness. The centrifugal blast surface preparationsystem must be engineered to achieve a Steel StructuresPainting Council (SSPC) SP-10 near-white finishwith a minimal surface profile at the desired linespeed. The primer application system must be capableof achieving complete coverage of both plate andshaped steel at a uniform dry film thickness. In termsof primer selection, the system must be suited to theshipyard’s welding processes and performanceexpectations, as well as to the expectations ofmaximum retention with reduced secondary surfacepreparation.

Primary Surface Preparation

INTRODUCTION:Primary surface preparation refers to the

preparation and painting of incoming structural steelplates and shapes prior to fabrication. Mill scale andrust are removed using centrifugal blasting equipmentand recyclable steel abrasives. The new steel is thencoated with a weld-through pre-construction primerto protect the surface from corrosion and preserve thesurface profile imparted during the cleaning process.Primary surface preparation methods are well suitedfor automation, and support the cost reductionstrategies of the MARITECH Advanced ShipbuildingEnterprise program. For shipyards that cannot usethe weld-through pre-construction primers, primarysurface preparation refers to the initial blast cleaningof structures prior to coating.

STATE OF THE INDUSTRY:The use of recyclable steel abrasives with automated

blast cleaning production lines represents the state ofthe industry for removing mill scale and corrosionproducts prior to applying the pre-constructionprimer. Mill scale and rust are removed from standardstructural shapes and steel plates in an efficient andeconomic manner. The use of recyclable steel abrasivesallows the desired surface profile to be imparted to thesteel, while producing a minimum of solid waste.

Following the blast cleaning process, a pre-construction primer is applied to the steel to protectthe surface from corrosion until the steel is needed fornew construction or repair. In recent years, pre-construction primers have been developed that do notrequire removal prior to cutting or welding of thesteel. Known as weld-through primers, these primercoatings produce substantial cost savings by reducingthe amount of manpower and material required toprepare the structural steel parts for assembly. Most

commercial shipyards or contracting authorities allowthe direct application of anti-corrosive paints andtopcoats over these pre-construction primers, at leastfor dry spaces, which further enhances the economicsof surface preparation and preservation. However,the recent trend toward 100% solids coatings maychange this approach depending on the ability of thesolids coatings to adhere well to the pre-constructionprimer.

STATE OF THE ART:The abrasive must impact the steel with enough

force to remove mill scale and rust, as well as imparta surface profile to the steel. The technology for thisprocess is well developed and relatively inexpensive.To advance beyond this level, other factors must beconsidered such as improving the longevity of thepaint system by reducing surface contaminants to anabsolute minimum; the continued development,appropriate use, and controlled application ofprotective coatings; and the increased use of roboticsin blasting technology to reduce the human element.One method of eliminating surface contaminants isby using ultra-high pressure (UHP) waterjet blastingwith garnet injection. UHP has been shown to reducechloride contamination to below detectable levelsusing ordinary municipal fresh water supplies.

The two primary factors that drive surfacepreparation technology are stricter environmentalregulations and economic issues. Primary surfacepreparation is performed indoors, which permits theuse of efficient controls for airborne emissions offugitive blasting dust and volatile organic compounds(VOCs). Consequently, process improvements andtechnologies (e.g., reduce material, manpower, andwaste disposal costs; improve operator health andsafety while lowering worker protection costs) havethe potential to increase shipyard competitivenessand advance the state of the art in shipbuilding.

STATE OF RELATED INDUSTRY:Other industries, specializing in the construction

of large, outdoor steel structures (e.g., bridges, watertowers, tanks), use a primary surface preparationsimilar to that of the shipbuilding industry. Steelshapes and subassemblies are blast-cleaned, primed,and shipped to the construction site for assembly. Inaddition, shipbuilding and non-shipbuilding industriesare both influenced by the same environmental andeconomic drivers.

The railcar industry is employing robotic blastmachines for its primary surface preparation. Thesemachines can use higher blast pressures than could

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be used by humans, resulting in faster cleaning rates.The large aircraft manufacturing industry also sharescharacteristics of the shipbuilding industry, althoughits challenges are significantly different. Here, largealuminum panels are first cut and shaped to netform, then an adhesive primer is applied usingautomated application equipment. Film thicknessand environmental conditions are closelycontrolled. Under these conditions, the aircraftindustry recognizes that the best corrosionprotection possible over the life of the aircraft isthe original equipment manufacturer (OEM) primerto substrate bond. Additionally, the surfacecleanliness and environmental conditions duringthe primer application of the secondary surfacepreparation operations will never match those ofthe OEM. The result is substantial ramificationswith regard to cost and waste reductions duringthe secondary surface preparation processes.

ENABLING TECHNOLOGIES:The development of weld-through primers has

reduced manufacturing costs and ensured surfacepreservation. In addition, 100% solids coatings arehaving a positive impact on VOC emissions. Asystems approach to the use of 100% solids coatingswith weld-through construction primers is requiredto preserve these manufacturing benefits.

MANUFACTURING STRATEGIES:The manufacturing strategy is to continue

maximizing the use of primary preparation andpre-construction primers for plates and shapes.This approach will provide good corrosionprevention during the fabrication process andreduce downstream coating costs.

Secondary Surface Preparation

INTRODUCTION:Secondary surface preparation refers to the re-

preparation and re-painting of steel structuresduring ship fabrication or repair. For newconstruction, this process is required for weldsand damaged areas after the structures have beenfabricated and prior to the application of the finalpaint system. Abrasive blasting is usually used toremove old coatings and corrosion products aswell as to impart a profile to the substrate. In caseswhere blasting is impractical, mechanical tools areused instead. Consequently, improvements intooling and coating systems can reduce the costs

and schedule impact from secondary surfacepreparation.

STATE OF THE INDUSTRY:Secondary surface preparation, by blasting, is

generally accomplished using recyclable steel shot,steel grit, mineral (garnet), or mineral slag abrasives.Small blast pots and abrasive hoppers are placed nearthe job site, and tarps or enclosures are used tocontain blasting debris. Vacuum systems recycle theabrasive. Dust collectors and ventilation equipmentare used to control the environment. Containment offugitive dust in tanks and voids is not difficult, butregardless of where performed, the ability to providesufficient ventilation and airflow to meet workerhealth and safety requirements adds an additionalcost and productivity burden. Prevention of fugitiveemissions during paint removal operations onsuperstructures can be accomplished by buildingplywood and lumber containment structures, or byusing the superstructure itself as the supportframework for polyethylene shrink-wrapcontainments.

Portable, centrifugal wheel, abrasive blastingmachines with recyclable steel abrasives are used toremove thick non-skid deck coatings. Vertically-oriented, centrifugal wheel, blasting machines canalso be used to remove coatings on hulls and boottops. In some cases, the use of recyclable abrasives isnot permitted on underwater hulls, so mineral slagabrasives (e.g., coal slag) are used to remove the paintsystem and prepare the underwater hull for paintapplication.

Mechanical secondary surface preparation isaccomplished with needleguns, disk sanders, roto-peen tools, and hand wire brushes. Some mechanicaltools have vacuum attachments to prevent workerexposure to heavy metals (e.g., lead, chromate) duringthe removal of old coatings.

STATE OF THE ART:Closed-cycle ultra-high pressure waterjet (UHPWJ)

blasting is quickly becoming the method of choice forremoving hull coatings. The water is near-instantaneously collected at the blast head, filtered,and reused, thereby eliminating the generation ofcollateral waste and leaving a surface free of chloridesand other contaminants. Garnet can be injected toimpart a profile to the surface, if necessary. Therecent trend has been to use magnetic crawlers tomanipulate the UHPWJ systems about the hull.Similar developments have occurred in the use of

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closed-cycle abrasive blast machines with magneticcrawlers for exterior hull blasting. Operators runthese machines at a distance via a joystick. Althoughexpensive to purchase, the closed-cycle abrasive blastmachines can be operated without shutting downadjacent hull fabrication work, which reducesdowntime and improves schedules.

A major improvement in state of the art involvesthe way paint removal is envisioned. The currenttrend is moving toward a tool-box approach forsecondary surface preparation. For complete removalof paint on hulls, UHPWJ systems are being employed.Portable, centrifugal blast machines throwingrecyclable steel grit are used for removing deckcoatings. For touching up paint damage, engineeredmedia such as sponge-jet urethane foam abrasive hasbeen investigated. To reactivate the surface of pre-construction primer prior to applying the final coatingsystem, CO2 pellet blast has been explored and showsgreat promise.

STATE OF RELATED INDUSTRY:Other industries, specializing in the repair of large,

outdoor steel structures, use recyclable steel abrasiveswith total containment as their primary method forsecondary surface preparation. Tanks can be cleanedusing UHPWJ systems, but the complexity of theshapes precludes this approach for repairing thecoatings on bridges and water towers. To remove leadpaint, chemical stripper systems such as Peel-Away®are used. While it is more expensive than openabrasive blasting, chemical stripping is approximatelyone-quarter to one-half the cost of building large,negative-pressure, containment structures andreduces worker exposure to toxic materials.

ENABLING TECHNOLOGIES:To determine the best match from all of the available

surface preparation technologies, organizations mustdetermine a more accurate cost estimate of a particularsurface preparation method, including equipment,materials, labor, and waste disposal. Currently inshipyards, the true cost of surface preparation isdifficult to estimate. Sponge-Jet® urethane foamabrasive, CO2 pellet blast, and other technologieshave been investigated to ascertain their potentialuse. Convincing management to employ a newtechnology requires solids, cost-saving estimates,particularly when large outlays for capital equipmentare necessary.

MANUFACTURING STRATEGIES:Many new techniques can reduce the costs of

secondary surface preparation. Among these arebetter scheduling of fabrication operations; use ofrobotic blasting machines; use of high pressurewaterjet and CO2 blasting techniques; and thedevelopment of more surface-tolerant coating systems.

Liquid Coating

INTRODUCTION:Liquid coating is the primary shipyard method for

protecting structures, components, and piping fromcorrosion. These coatings also provide resistance tofouling; increase fire resistance; identify safetyrequirements; and support habitability schemes.Application of liquid coatings to ships is still verylabor intensive and costly. However, state-of-the-artmethods are available to reduce these costs andshorten preservation schedules.

STATE OF THE INDUSTRY:Liquid coatings are applied by brushes, rollers, and

spray equipment. The choice of spray equipment isdetermined by the type and viscosity of the coating tobe applied; the type and size of area to be coated; andthe desired surface finish.

Conventional equipment pressurizes paint with airto push the liquid/air mixture through a hose andatomize it in the spray gun at approximately 30 to 40psi. Airless equipment uses an air-driven pump topush only the liquid through the hose using a spraygun tip pressure of around 3,000 to 4,500 psi. Thehigher pressure permits the application of higherviscosity coatings and larger volumes of paint perunit time. Air-assisted airless equipment is similarexcept that it operates at a spray gun tip pressure ofless than 950 psi. The lower pressure allows bettercontrol of the flow stream and applied thickness.High volume-low pressure (HVLP) equipment useslow pressures for applying interior enamels andcreates virtually no overspray. The spray gun tippressure is typically five to ten psi. Plural componentequipment uses separate fluid pumps to force resinand catalyzed components through a static mixer andthen to the spray gun. This equipment can applycoatings with very high viscosities and short pot livesusing spray gun pressures from 4,000 to 7,000 psi.

Two component epoxy paints are the predominantanti-corrosive coatings for shipyards, with lesseramounts of inorganic zinc, alkyd, latex, and acryliccoatings used. High solids epoxy paints (less than

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20% solvent) are being used for tank interiors andfree-flood spaces. Their higher viscosity allows betterprotection in fewer coats, which reduces labor costs.Inorganic zinc, pre-construction primers areapplied automatically to plates and shapes prior tofabrication. These coatings can be welded through,and their zinc content prevents corrosion untilfinal painting (interior dry spaces only) or removalfor applying epoxy paints in wetted or immersedareas.

STATE OF THE ART:Automated, pre-construction, priming lines are

state of the art for plates and shapes. Pluralcomponent equipment is state of the art for applyinghigh viscosity, multi-component paints to hulls,free-flood spaces, and tank interiors. Pluralcomponent equipment only mixes what will besprayed and reduces waste of multi-componentpaints. This method also reduces the amount ofsolvent needed to clean equipment because onlythe static mixer, downstream hose, and spray gunare exposed to the catalyzed paint. A drawback toplural component equipment is the high initialcost. HVLP equipment is state of the art forapplying low viscosity, interior, finish enamels bygreatly reducing the masking of adjacent areaswhich, in turn, reduces labor costs.

STATE OF RELATED INDUSTRY:The railcar industry has used plural component

spray equipment for years to apply high viscositycoatings. The automotive industry relies onelectrocoating and robotic spray applicationmethods. Electrocoating is not presently used bythe shipbuilding industry and robotic applicationof coatings is limited to pre-construction priminglines and automated powder coating applications.These related industries are also ahead of theshipyards in their methods employed to identifyand track liquid coating of parts. Barcodes andelectronic buttons attached to parts can be scannedto ensure that the correct liquid paint is applied.Infrared sensors have been developed for paintspray guns by the automobile repair industry toensure the painter maintains a constant, uniformdistance from the substrate, thereby improvingthe quality of the finish.

ENABLING TECHNOLOGIES:Automatic mixing and dispensing equipment for

paints can decrease labor costs and reduce waste.Robotic application of coatings is suitable for

repetitious applications for standard shapes orstructures. Electronic technologies can supportbetter tracking of parts through the preservationprocess, and ensure that the correct coatings areapplied. Computerization of warehouse inventoriesand paint issue points in shipyards can supportmore efficient use of coatings and reduce costlywaste.

MANUFACTURING STRATEGIES:Better computerization of liquid coating inventories

and just-in-time deliveries can reduce costs. Improvedtraining of production planners in surface preparationand painting requirements can better integrate paintprocesses into the rest of the ship fabrication work.Continued use of pre-construction primers as well asthe development of better topcoats to eliminatesecondary surface preparation would improve liquidcoating processes and reduce costs.

Powder Coating

INTRODUCTION:Powder coating is a process in which partially

catalyzed resins and curing agents in a powder formare applied to metal parts, and then baked in an oven.The heat from the oven causes the powder to liquefy,flow, gel, and harden — thereby making a uniformcontinuous film that is tough and durable. Powdercoatings do not emit solvents to the environment, nordo they create hazardous waste. The coatings aretypically applied by electrostatic spray equipment orwith fluidized beds. The parts being coated must beable to withstand the surface preparation method(e.g., typically an abrasive blast) and the powdercuring temperature (e.g., 300°F to 400°F for 20minutes). The increased use of powder coatings inshipyards can greatly reduce labor costs forpreservation as well as provide more durable coatingsystems.

STATE OF THE INDUSTRY:Over the last seven years, several major U.S.

shipyards have installed powder coating facilities.These facilities perform either batch work on a fewparts at one time or use automated equipment thatcan coat thousands of parts per week. The majorityof parts weigh between 10 and 150 pounds, althoughparts of up to 6,000 pounds have been coated in batchoperations. Pipe and electrical hangers, fixtures,small foundations for machinery, hatches, louvers,deck plates, gauge boards, furniture, and

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miscellaneous structures are routinely powder coated.Gas-fired convection ovens are most frequently usedfor curing. Automated facilities can be operated byone or two workers, which greatly reduces laborcosts for the preservation process. Some shipyardscontract their powder coating work to outside jobshops, especially for hangers and furniture. Powdercoating of large parts for ships has rarely been done,but has the potential to reduce coating costs.

STATE OF THE ART:Infrared ovens can raise the surface temperature of

a part to the powder curing temperature withoutheating the entire unit, which is conducive to quickercuring times and increased through-put. Ultraviolet(UV) light curing methods are used in non-marineindustries to quickly cure thin films. Some commercialpowder coating companies have coated steel parts ofup to 30 tons (e.g., bridge girders). Special electrostaticspray guns are available that can overcome theFaraday cage effect that prevents powder from beingapplied to recesses and tight spaces. Large fluidizedbed units can apply uniform powder thicknesses tocomplex shapes. Laser inspection devices are beingdeveloped to measure the thickness of applied powder,prior to baking, to ensure first-time quality.

STATE OF RELATED INDUSTRY:Hundreds of commercial powder coating companies

can be found throughout the U.S., and there are alsomany appliance and metal furniture manufacturers,automobile makers, and electronic industry suppliersthat apply powder coatings. Infrared ovens; UVcuring methods; and robotic application of powderare often used by companies that coat large numbersof similarly shaped parts. Most shop setups can makequick color changes and apply a wide variety ofpowder formulations. Non-marine industries typicallyapply thinner films of powder coating compared towhat is needed for good performance in marineenvironments.

ENABLING TECHNOLOGIES:Infrared ovens; UV curing methods; and robotic

application of powder have the potential to extend thepowder coating process to more shipbuilding partsthan currently being addressed. Infrared ovens raisethe surface temperature of a part to the powdercuring temperature without heating the entire unit,which reduces process times. UV curing methodsmay be suitable for interior dry spaces where thinpowder films are acceptable. Improved handlingmethods would allow larger parts to be coated.

MANUFACTURING STRATEGIES:Maximizing the use of powder coatings in

shipbuilding requires a good understanding of themanufacturing requirements for the parts. Partsmust be sent to the powder coating shop at the propertime in the construction cycle to benefit from thequick curing times, and to obtain the best coveragewhile minimizing downstream paint repairs. Partsmust also be able to withstand the oven temperaturesneeded to cure the powder.

Environmental Technologies

INTRODUCTION:Environmental technologies are used to comply

with federal, state, and local environmentalregulations for air quality, water quality, andhazardous waste management. These technologiesalso include methods to control temperature, relativehumidity, dew point, solvent vapor concentrations,and other similar conditions during surfacepreparation and coating operations. Environmentalcompliance and control technologies can directlyimpact shipyard profits. Consequently, a variety oftechnical methods are available for meeting thesechallenges.

STATE OF THE INDUSTRY:Shipyard preservation operations are subject to

federal, state, and local environmental regulationsfor air quality, water quality, and hazardous wastemanagement. In 1998, new federal regulations wereinvoked for controlling solvent emissions fromshipyard paints. Most shipyards limit these emissionsby controlling the solvent content in the purchasedpaint and by eliminating thinning, rather thanemploying control equipment to filter, capture, anddestroy solvent vapors. Some local air quality permitsmandate specific spray equipment to improve painttransfer efficiency and reduce emissions. Shipyardsuse dust collection systems, tents, and/or tarps tocontrol paint overspray and to meet federal regulationsfor emission of nuisance dust. Many shipyards usesolvent stills to reduce their solvent wastestreamsand to recycle solvent for cleaning spray equipment.Blowers help keep paint solvent vapor concentrationsin confined spaces below explosive limits, whilerefrigerant, desiccant, and compressed air dryershelp shipyards comply with paint manufacturer’sinstructions for temperature, relative humidity, anddew point. A key environmental issue for shipyards ispreventing the discharge of drydock liquid wastes

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that contain heavy metals generated by paint removaland application operations. Frequent sampling ofdrydock wastewater and its associated control areincreasingly expensive burdens to shipyards.

STATE OF THE ART:Technology for maintaining air quality includes

dry filtration systems, impaction devices (e.g., watercurtains), electrostatic precipitators, and organicvapor control devices (e.g., carbon adsorption). Riskcan be a factor if the use of this equipment becomes acondition of one’s air quality permit. Should theequipment break or malfunction, the paint shopoperations must shut down, thereby impacting shipfabrication schedules. Biodegradable materials inwastewater can be handled with aerobic and anaerobictreatment processes. Non-biodegradable materialsare controlled with advanced oxidation, carbonadsorption, or thermal destruction methods.Wastewater-suspended, solids treatment processesinvolve gravity separation and clarification; filtration-plate and frame pressure; filtration with mono- andmulti-media; pre-coat filtration; and, most recently,membrane or ceramic ultrafiltration. Solid waste canbe reduced with high pressure waterjet blasting,instead of abrasive blasting, by using proportionalmixers and pumps for multi-component coatings, byusing large volume storage containers (e.g., 400-gallon totes), and by using improved application gunsthat reduce paint overspray. Disposal of sludge viathickening processes may reduce wastewater solids.Filter presses, decanters, and industrials centrifugesare available to concentrate sludges in a tertiarytreatment process.

STATE OF RELATED INDUSTRY:National emission standards for hazardous air

pollutants have and are being formulated for othermajor industries that use coatings (e.g., aircraft,furniture, appliance, electronic products). The solventemission limits for these coatings are different; hence,the coating solutions are not necessarily transferableto the shipbuilding industry. The size and shape ofrelated industry’s products are more conducive totechnological controls for capturing solvent vapors,whereby most of the surface areas of ships are paintedin outdoor environments or large buildings. In someindustries, the use of powder coatings has significantlyreduced solvent emissions and hazardous waste. Thetechnologies used for environmental compliance byrelated industries must be studied on a case-by-casebasis to determine their feasibility for shipyards.

ENABLING TECHNOLOGIES:The computerization of inventories and tracking of

paint usage can help ensure compliance to solventemission regulations. Improvements in waterbornecoating chemistry may ease the environmental burdenassociated with solvent-borne paints. Waterjetblasting can easily remove old coatings and cleansurfaces while producing low volumes of waste;however, issues regarding overcoating of flash rustmust be resolved. High-powered vacuum systems canbe used to control and capture spent abrasive andliquid wastes.

MANUFACTURING STRATEGIES:By minimizing the number and types of coatings to

be applied, the overall environmental impact can bereduced. Low solvent content coatings, waterbornecoatings, and powder coatings that usually achieveequivalent performance levels as high solvent contentcoatings have been developed for marine applications.Performing surface preparation and painting at theproper time in the fabrication sequence can reducepaint re-work and its corresponding environmentalimpact. Plural component mixing and spray equipmentcan reduce hazardous wastes from multi-componentpaints.

Quality Management

INTRODUCTION:Quality management is the process by which the

quality of purchased coatings, surface preparations,coating applications, curing, and final acceptance isachieved. This process also involves the training ofpaint shop and inspection personnel on qualityattributes. Shipyard preservation costs can be reducedby developing clear and focused quality managementprograms, and by increasing the level ofcomputerization of the quality process.

STATE OF THE INDUSTRY:U.S. shipyards have adopted various quality

management programs whose individual history canusually be traced to a specific quality problem at thatshipyard. In addition, all shipyards provide someform of on-the -job or formal training, relative toquality attributes, to their blasters and painters.Paint inspectors attend either in-houses courses orthose offered by professional technical societies suchas the SSPC or the National Association of CorrosionEngineers (NACE). Shipyard painting procedurestypically contain hold-points for inspection of surface

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preparation; compliance to surface preparation visualstandards; measurement of film thicknesses; evaluation ofenvironmental conditions; ventilation methods; andcompliance with paint manufacturer’s instructions.Inspection tools include replica tape for measuring blastprofiles; electronic or mechanical devices for measuringpaint thicknesses and environmental conditions; chemicaltests to determine the presence of detrimental chlorides;and video cameras to record conditions to track coatingperformance. A key issue affecting quality is trying todetermine the ideal time in the fabrication process toperform preservation. If preservation is performed toosoon, additional costs for re-work of paint damage causedby other shipyard operations may occur. If preformed toolate, additional costs may be necessary to ensure that thepreservation process does not impact adjacently installedcomponents or machinery.

STATE OF THE ART:Improved computerization of paint thickness gauges

allows thousands of measurements to be automaticallyrecorded and downloaded to a personal computer forevaluation, process control, and tracking of coatingperformance. Digital cameras allow quick and easyrecording of paint conditions, and enable electronic transferof data for quick disposition of repair instructions.Electronic devices are available for on-site measurement ofresidual chlorides after blasting. The U.S. Navy usesrobots to inspect the paint conditions on underwater hulls,thereby avoiding costly drydocking. Ultrasonic gaugesare being developed which can detect subsurface coatingflaws on composite materials. This technology may be ableto detect corrosion activity occurring at the juncture of thesubstrate and coating, even when no visual changes incoating appearance are present. Pictorial standards havebeen developed for abrasive waterjetting.

STATE OF RELATED INDUSTRY:Total quality management and ISO-9000 certification

programs have raised the quality level of coatings for theautomotive industry, appliance manufacturers, and makersof other consumer goods. The quality required in theseindustries for finish and appearance is generally muchhigher than those of the shipbuilding industry. Otherindustries such as bridge and refinery painting contractorsuse SSPC- or NACE-certified, third-party inspectors toensure the quality of coatings. Non-marine industriesemploy a greater amount of specialized instrumentation toevaluate coatings for attributes such as gloss andwaviness.

ENABLING TECHNOLOGIES:Electronic measuring devices enable coating quality

data to be evaluated quickly and consistently.Laboratory analysis equipment can verify that goodquality coatings are received and can evaluateproduction problems. The adaptation of statisticalprocess control techniques to paint shop operationswould provide a better understanding of cost driversand areas needing improvement. Better planning andscheduling programs would also allow preservationto be performed at the optimum time in the shipfabrication process, thereby reducing re-work costs.

MANUFACTURING STRATEGIES:Increased computerization of quality procedures

and attributes can significantly improve quality andreduce costs for shipyard painting practices. Theability to transmit electronic images of good qualityand unacceptable paint conditions to the job site canhelp resolve quality issues in a more timely fashion.Electronic transmission of inspection reports anddata will provide a faster method for determiningquality trends and areas needing improvement.Dissemination of paint requirements and proceduresvia remote terminals, rather than hard copy procedures,offers faster responses to questions by shipyard trades.Selecting the optimum time during fabrication toperform preservation can significantly reduce re-work costs.

POINTS OF CONTACT:For further information on SP-3 Panel items in this

report, please contact:

Mr. Mark PanoskyGeneral Dynamics, Electric Boat Corporation(860) [email protected]

Mr. Scott DeVinneyGeneral Dynamics, Bath Iron Works(207) [email protected]

Mr. Charles TricouApplied Research LaboratoryThe Pennsylvania State University(814) [email protected]

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Table of Acronyms

Acronym Definition

APS Atmospheric Plasma SprayingASE Advanced Shipbuilding EnterpriseATICTS Automatic Tooling Inventory Control Tracking System

CAD Computer Aided DesignCAM Computer Aided ManufacturingCFM Continuous Flow ManufacturingCNC Computer Numerical Control

DFMA Design for Manufacturing and AssemblyDNC Direct Numerical Control

EAS Electric Arc SprayingEB-NV Electron Beam Non-VacuumEBW Electron Beam WeldingEGW Electrogas WeldingESW Electroslag Welding

FCAW Flux Cored Arc WeldingFSW Friction Stir Welding

GMAW Gas Metal Arc WeldingGTAW Gas Tungsten Arc Welding

HSLA High Strength Low AlloyHVLP High Volume-Low PressureHVOF High Velocity Oxy-fuelHY High Yield

JIT Just-In-Time

LW Laser Welding

NACE National Association of Corrosion EngineersNC Numerical ControlNDE Non-Destructive EvaluationNDT Non-Destructive TestingNSRP National Shipbuilding Research Program

OEM Original Equipment Manufacturer

PAW Plasma Arc Welding

RW Resistance Welding

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Acronym Definition

SAW Submerged Arc WeldingSMAW Shielded Metal Arc WeldingSOA State of the ArtSSPC Steel Structures Painting CouncilSW Stud Welding

UHP Ultra-High PressureUHPWJ Ultra-High Pressure WaterjetUV Ultraviolet

VOC Volatile Organic CompoundVPPA Variable Polarity Plasma Arc

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Contributors

Joseph C. BaumerNewport News Shipbuilding(757) [email protected]

Larry L. BlanchfieldNewport News Shipbuilding(757) [email protected]

Hank L. BowersNewport News Shipbuilding(757) [email protected]

Howard Bunch (retired)University of Michigan TransportationResearch [email protected]

Tommy CauthenIngalls Shipbuilding(228) [email protected]

Scott DeVinneyBath Iron Works(207) [email protected]

J. L. ‘Bull’ DurhamNewport News Shipbuilding(757) [email protected]

Clifford DutrumbleElectric Boat Corporation(860) [email protected]

Suren DwivediUniversity of Louisiana(318) [email protected]

Ed HansenBath Iron Works(207) [email protected]

Richard HoldrenEdison Welding Institute(614) [email protected]

Doug KetronEdison Welding Institute(614) [email protected]

Lee KvidahlIngalls Shipbuilding(228) [email protected]

Suzane LavoieElectric Boat Corporation(860) [email protected]

Michael LudwigBath Iron Works(207) [email protected]

Warren MayottElectric Boat Corporation(860) [email protected]

Jerry M. McVeighNewport News Shipbuilding(757) [email protected]

Rick NelsonElectric Boat Corporation(860) [email protected]

Mark PanoskyElectric Boat Corporation(860) [email protected]

Charles RibardoEdison Welding Institute(614) [email protected]

Allan G. RoyNewport News Shipbuilding(757) [email protected]

James SawhillNewport News Shipbuilding(757) [email protected]

David D. SawyerNewport News Shipbuilding(757) [email protected]

Charles TricouApplied Research LaboratoryThe Pennsylvania State University(814) [email protected]

John TalkingtonEdison Welding Institute(614) [email protected]

Joseph Bart SicklesConcurrent Technologies Corporation(814) [email protected]

Mike SullivanNational Steel and Shipbuilding Company(619) [email protected]

Warren W. VickNewport News Shipbuilding(757) [email protected]

Matthew WhiteNavy Joining CenterEdison Welding Institute(614) [email protected]

Dave G. WilliamsNewport News Shipbuilding(757) [email protected]

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Navy Manufacturing Technology Centers of Excellence

The Navy Manufacturing Sciences and Technology Program established the following Centers of Excellence(COEs) to provide focal points for the development and technology transfer of new manufacturing processes andequipment in a cooperative environment with industry, academia, and Navy centers and laboratories. TheseCOEs are consortium-structured for industry, academia, and government involvement in developing andimplementing technologies. Each COE has a designated point of contact listed below with the individual COEinformation.

Best Manufacturing Practices Centerof Excellence

The Best Manufacturing Practices Center of Excel-lence (BMPCOE) provides a national resource toidentify and promote exemplary manufacturing andbusiness practices and to disseminate this informa-tion to the U.S. Industrial Base. The BMPCOE wasestablished by the Navy’s BMP program, Departmentof Commerce’s National Institute of Standards andTechnology, and the University of Maryland at Col-lege Park, Maryland. The BMPCOE improves the useof existing technology, promotes the introduction ofimproved technologies, and provides non-competitivemeans to address common problems, and has becomea significant factor in countering foreign competition.

Point of Contact:Mr. Ernie RennerBest Manufacturing Practices Center ofExcellence4321 Hartwick RoadSuite 400College Park, MD 20740(301) 403-8100FAX: (301) [email protected]

Center of Excellence for CompositesManufacturing Technology

The Center of Excellence for Composites Manufactur-ing Technology (CECMT) provides a national re-source for the development and dissemination ofcomposites manufacturing technology to defense con-tractors and subcontractors. The CECMT is managedby the Great Lakes Composites Consortium andrepresents a collaborative effort among industry,academia, and government to develop, evaluate, dem-onstrate, and test composites manufacturing tech-nologies. The technical work is problem-driven toreflect current and future Navy needs in the compos-ites industrial community.

Point of Contact:Mr. James RayCenter of Excellence for Composites ManufacturingTechnologyc/o GLCC, Inc.103 Trade Zone DriveSuite 26CWest Columbia, SC 29170(803) 822-3708FAX: (803) [email protected]

Electronics Manufacturing ProductivityFacility

The Electronics Manufacturing Productivity Facility(EMPF) identifies, develops, and transfers innovativeelectronics manufacturing processes to domestic firmsin support of the manufacture of affordable militarysystems. The EMPF operates as a consortium com-prised of industry, university, and government par-ticipants, led by the American Competitiveness Insti-tute under a CRADA with the Navy.

Point of Contact:Mr. Alan CriswellElectronics Manufacturing Productivity FacilityOne International PlazaSuite 600Philadelphia, PA 19113(610) 362-1200FAX: (610) [email protected]

National Center for Excellence inMetalworking Technology

The National Center for Excellence in MetalworkingTechnology (NCEMT) provides a national center forthe development, dissemination, and implemen-tationof advanced technologies for metalworking productsand processes. The NCEMT, operated by ConcurrentTechnologies Corporation, helps the Navy and defensecontractors improve manufacturing productivity and

part reliability through development, deployment,training, and education for advanced metalworkingtechnologies.

Point of Contact:Mr. Richard HenryNational Center for Excellence in MetalworkingTechnologyc/o Concurrent Technologies Corporation100 CTC DriveJohnstown, PA 15904-3374(814) 269-2532FAX: (814) [email protected]

Navy Joining Center

The Navy Joining Center (NJC) is operated by theEdison Welding Institute and provides a nationalresource for the development of materials joiningexpertise and the deployment of emerging manufac-turing technologies to Navy contractors, subcontrac-tors, and other activities. The NJC works with theNavy to determine and evaluate joining technologyrequirements and conduct technology developmentand deployment projects to address these issues.

Point of Contact:Mr. David P. EdmondsNavy Joining Center1250 Arthur E. Adams DriveColumbus, OH 43221-3585(614) 688-5096FAX: (614) [email protected]

Energetics Manufacturing Technology Center

The Energetics Manufacturing Technology Center(EMTC) addresses unique manufacturing processesand problems of the energetics industrial base toensure the availability of affordable, quality, and safeenergetics. The focus of the EMTC is on processtechnology with a goal of reducing manufacturingcosts while improving product quality and reliability.The EMTC also maintains a goal of development andimplementation of environmentally benign energeticsmanufacturing processes.

Point of Contact:Mr. John BroughEnergetics Manufacturing Technology CenterIndian Head DivisionNaval Surface Warfare Center101 Strauss AvenueBuilding D326, Room 227Indian Head, MD 20640-5035(301) 744-4417DSN: 354-4417FAX: (301) [email protected]

Institute for Manufacturing andSustainment Technologies

The Institute for Manufacturing and SustainmentTechnologies (iMAST), was formerly known as Manu-facturing Science and Advanced Materials ProcessingInstitute. Located at the Pennsylvania StateUniversity's Applied Research Labortory,the primary objective of iMAST is to address chal-lenges relative to Navy and Marine Corps weaponsystem platforms in the areas of mechnical drivetransmission techologies, materials science technolo-gies, high energy processing technologies, and repairtechnology.

Point of Contact:Mr. Henry WatsonInstitute for Manufacturing and SustainmentTechnologiesARL Penn StateP.O. Box 30State College, PA 16804-0030(814) 865-6345FAX: (814) [email protected]

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National Network for Electro-OpticsManufacturing Technology

The National Netowork for Electro-Optics Manufac-turing Technology (NNEOMT), a low overhead vir-tual organization, is a national consortium of electro-optics industrial companies, universities, and govern-ment research centers that share their electro-opticsexpertise and capabilities through project teams fo-cused on Navy requirements. NNEOMT is managedby the Ben Franklin Technology Center of WesternPennsylvania.

Point of Contact:Dr. Raymond V. WickNational Network for Electro-Optics ManufacturingTechnologyOne Parks BendBox 24, Suite 206Vandergrift, PA 15690(724) 845-1138FAX: (724) [email protected]

Gulf Coast Region Maritime TechnologyCenter

The Gulf Coast Region Maritime Technology Center(GCRMTC) is located at the University of New Or-leans and focuses primarily on product developmentsin support of the U.S. shipbuilding industry. A sistersite at Lamar University in Orange, Texas focuses onprocess improvements.

Point of Contact:Dr. John Crisp, P.E.Gulf Coast Region Maritime Technology CenterUniversity of New OrleansCollege of EngineeringRoom EN-212New Orleans, LA 70148(504) 280-5586FAX: (504) [email protected]

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Manufacturing Technology Transfer Center

The focus of the Manufacturing Technology TransferCenter (MTTC) is to implement and integrate defenseand commercial technologies and develop a technicalassistance network to support the Dual Use Applica-tions Program. MTTC is operated by InnovativeProductivity, Inc., in partnership with industry, gov-ernment, and academia.

Point of Contact:Mr. Raymond ZavadaManufacturing Technology Transfer Center119 Rochester DriveLouisville, KY 40214-2684(502) 452-1131FAX: (502) [email protected]

the shipyard state of the art report may 2000 - …bmpcoe.org/library/pdf/soa.pdf · punching and...

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