navsea documents - society for protective coatings€¦ · 4 navsea documents nstm chapter 631...

Topics: NAVSEA documents related to preservation of ships•Exercise in use of these documents•

Scope This section gets students acquainted with guidance documents for the preservation of ships.

Learning OutcomeAt the end of this section, students will be able to:

Identify the major NAVSEA guidance documents concerning the •preservation of ships and describe how to use them in their work.

NAVSEA has prepared detailed guidance documents for the different aspects of shipboard corrosion control by coatings. These documents include:

Naval Ships Technical Manual, Chapter 631, Preservation of Ships in •ServiceNaval Ships Technical Manual, Chapter 634, Preservation of Ships in •Service GeneralNAVSEA Standard Item 009-32, Cleaning and Painting Requirements•NAVSEA Standard Item 009-04, Quality Management System•NAVSEA Coating Performance Specifications (e.g., MIL-PRF-23236, •MIL-PRF-24647 and MIL-DTL-24441) with supporting Qualified Products Databases and NAVSEA-Reviewed ASTM F718 Data Sheets

4 NAVSEA Documents

NSTM CHAPTER 631 OVERVIEW

Section 1 - Introduction Reference Documents General Painting Requirements Coating Selection

Section 2 - Safety General Hazards General Paint/Solvent Information for Fire/Explosion Paint and Solvent Health Hazards Surface Preparation/Paint Removal Methods and Tools

Paint Mixing

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Paint Application Specific Coating System Concerns

Section 3 - Paint Equipment Paint Thickness Gages Paint and Paint Materials

Section 4 - Reconditioning Flooded and Smoke-Contaminated EquipmentSection 5 - Surface Preparation Surface Cleaning Methods Abrasive Blasting Waterjetting and Water cleaning Underwater Hull Cleaning Solvent Cleaning Acid Cleaning Paint Removers Steam Cleaning Pickling Alkaline Cleaning Hand Cleaning of Ship’s Bilges Preparation Quality Assurance Tests, Inspections and Records

Section 6 - Paint Application Guidance and Requirements Painting Records, Reports and Documents Basic Preparations Basic Painting Procedures Paint Failures

Section 7 - Paint Application Procedures Epoxy Polyamide Coatings (MIL-DTL-24441) MIL-PRF-23236 Coatings Pretreatment Wash Primer Vinyl Plastisol Coatings Thermal Spray Coatings Erosion-Resistant Epoxy Coatings Antisweat Treatment and Compound Powder Coatings TT-P-28 Heat-Resistant Coatings Water-based Coatings MIL-PRF-24596 Epoxy Repair and Hull Smoothing Compounds

Section 8 - Shipboard Paint Application General Requirements and Guidance for Metal Surfaces General Requirements and Guidance for Non-Metallic Surfaces Surface Ships and Craft Underwater Hull Coatings Potable Water Tank Coating Systems

NSTM CHAPTER 631 OVERVIEW (continued)

Navy Basic Paint Inspector Training: NAVSEA Documents

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Feed Water and Fresh Water Drain Collection Tank Coating Systems Machinery and Piping Electrical and Electronic Equipment Motor and Generators Electric Cables and Supports Metal Enclosures Interior Communication and Fire Control Equipment Lighting Systems Exterior Radar, Fire Control, Antennas and electronic Equipment Sonar Domes Miscellaneous Equipment Shipboard Hems not to be Painted Surface Ships Hospital Ships Submarines

Section 9 - Boats and Small Craft Above-Water Surfaces Underwater Surfaces Miscellaneous Equipment Open Boats Cabin Boats Boats for Hospital Ships Identification Markings Plastic Boats

Section 10 - Naval Ship’s Markings and Awards Ship Names Ship Nameboard Draft Marks Distinguishing Numerals and Letters Letter Awards Ship and Small Craft Insignias Hospital Ships

Section 11 - Quality Assurance for Critical Coated Areas Defined Critical Coated Areas Required for Critical Coated Areas Test and Inspection Records Shipyard Blaster and Painter Certification Coating Inspector Certification Coating Inspector Responsibilities Inspection of Storage and Receipt Inspection Facilities In-process Inspections Audits of Facility and In-process Inspections Inspection of Final Coatings System Review of Records for Final Coating Evaluation Acceptance/Rejection of Final Coating Systems


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NAVSEA COATING PERFORMANCE SPECIFICATIONS AND SUPPORTING DOCUMENTS

NAVSEA STANDARD ITEM 009-32 OVERVIEW

NAVSEA STANDARD ITEM 009-04 OVERVIEW

NAVSEA Standard item 009-04 provides quality management requirements for Navy products, including cleaning and painting work. It describes requirements to establish, document, implement, and maintain a Quality Management System as a means of ensuring the product conforms to specified requirements. These include:

Corrective and preventive action programs•A test and inspection plan•Documentation procedures•

NAVSEA Standard Item 009-32 provides cleaning and painting requirements for Navy ships. This information covers the following general subjects:

Definitions of critical coated areas and technical terms used•Blast cleaning, including profile and cleanliness•Application, including striping and special (e.g., topcoating) application •concerns Use of specialized coatings, including nonskid, antifouling, fire-•retardant, and powder coatingsQuality assurance requirements, including inspection forms for •documentationEight tables of approved surface preparation and coating systems for •different surface areas.QA Inspection forms•

NAVSEA has the responsibility for many military performance specifications related to coatings for ships. Three of the more important of these are MIL-PRF-24647, MIL-PRF-23236 and MIL-DTL-24441. MIL-PRF-23236 and MIL-DTL-24441 are applicable to tanks, including potable water tanks and other ship structures, interior, or exterior for corrosion control. MIL-PRF-24647 is applicable to paint systems, anticorrosive and antifouling, for ship hulls.

Section 12 - Preservation Process Instructions Approved Preservation Process Instructions Preservation Process Instruction Availability Technical Conflicts Quality Assurance Forms

NSTM CHAPTER 631 OVERVIEW (continued)


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Associated with these documents are Qualified Products Databases (QPDs) and NAVSEA-reviewed ASTM F718 Data Sheets and any NAVSEA periodic Advanced Coating, Covering and Cleaning Systems messages. The QPDs list the commercial products approved under the requirements of the particular performance specification for use by or for the government in the acquisition of these products. The NAVSEA-reviewed ASTM F718 Data Sheets are short (about two pages) summaries prepared by the manufacturer of each approved product to provide identification and use of the product:

1. Generic type and description 2. Manufacturers data 3. Properties 4. Surface preparation minimum requirements 5. Mixing procedure 6. Application

There is a special highlighted section for Special Safety Precautions.

Other Qualified Products and Government specifications can be found at http://assist.daps.dla.mil/online/start/.

The following questions are intended to familiarize you with the NAVSEA documents described in this section. The questions should be divided so that each team has a question from each document. Questions 1 through 5 can be answered using information found in 009-32. Questions 6 through 9 can be answered using information in 009-04. Questions 10 through 16 can be answered using information in NSTM Chapter 631.

1. Which type and class of MIL-PRF-23236 products are exempt from dew point and relative humidity requirements?

2. What type of fire retardant paints should be used in preference to chlorinated alkyd fire retardant paints?

3. What is the definition of a tack coat?

NSTM CHAPTER 631 STANDARD ITEMS 009-32 AND 009-04 TEAM EXERCISE


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4. How many profile readings shall be taken in the first 1,000 square feet of a blast cleaned steel surface?

5. Upon completion of surface preparation are pH measurements required? If you answered yes, what is the acceptable pH range?

6. When is the use of black-oxide coated brass threaded fasteners (BOCBTF) authorized under contract work?

7. When must an initial copy of the Test and Inspection Plan be submitted to the Supervisor?

8. At what times shall the Test and Inspection Plan be revised and updated?

9. When must Test and Inspection records be documented?

NSTM CHAPTER 631 STANDARD ITEMS 009-32 AND 009-04 TEAM EXERCISE (continued)


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10. In which section and specific paragraphs would you find information regarding Personal Protection Equipment (PPE)? Name three pieces of PPE listed.

11. Where would you find information about surface preparation for aluminum surfaces? What is recommended for spot cleaning?

12. What type of brush is recommended for use with latex paints?

13. When does bleeding occur?

14. Where can you find information regarding powder coatings? Where are powder coatings used?

15. When using MIL-DTL-24441 epoxy paint, if the ambient temperature is 75°F, what is the minimum drying time between coats?

16. What is the impact of excessively applied or inadequately cured potable water tank coatings? Where did you locate information on coating these tanks?


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Complete the team exercise making use of the following documents:

NAVSEA Standard Item 009-32•MIL-PRF-24647•NAVSEA-Reviewed ASTM F718 Datasheets•QPD-24647•

A DDG-47 Class Navy Ship has entered a scheduled dry-dock availability. The contract calls for complete removal of the existing underwater hull coating system, followed by application of an approved copper-ablative antifouling (AF) system. A 12-year service life is required.

YourteamistochooseaspecificcoatingsystemandoverseetheQAforthisjob. To that end, your team needs to answer the following questions:

1. What document specifies the required surface preparation and coating specification for the underwater hull?

2. What performance specification is required for the 12-year ablative underwater hull system? Where specifically is the requirement found?

3. What level of surface preparation is required, prior to the application of the new AF system? Where is this specified?

4. The following additional information is known:

The temperature is expected to be around 38°F during the application.•Environmental regulations require that the volatile organic content •(VOC) of the AF topcoats shall not exceed 400 g/L, and that the VOC of any other individual paint in the system shall not exceed 340 g/L.

Using MIL-PRF-24647, classify the required coating system as to Type, Class, Grade, and Application. Explain your choice.

DOCUMENTATION TEAM EXERCISE


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5. Using the qualified products database, QPD-24647, and the classification required in question 4, pick a manufacturer and coating system to meet the requirements of this job.

6. After you have made your selection, one of the shipyard painters mentions that there is a sufficient quantity of an International AF system in stock. This system consists of Intergard 264 (anticorrosive coating) and Interspeed 640 (AF coating). On checking QPD-24647, you determine this system is classified as Type I, Class 1, Grade A, Application 3. Is this system suitable for your application? Why or why not?

7. What certifications are required for the following personnel? Why?

Abrasive blasters? •Coating Inspectors? •Contractor(s) performing the blasting and painting operations? •

SUMMARY

This chapter has discussed and described those NAVSEA guidance documents for the preservation of ships and described how to use them. The different documents relate to different aspects of shipboard corrosion control by coatings.

Topics• Solventcleaning• Chemicalcleaning• Steamcleaning• Detergent/watercleaning

Scope Thissectiongetsstudentsacquaintedwiththeuseofliquidproductsusedincleaningsurfacesofshipspriortocoating.

Learning Outcome Attheendofthissection,studentswillbeabletodescribethesecleaningmethodsandidentifytheirtypicaluses,advantages,andlimitations.

Thissectiondiscussestheuseofliquidcleaningmaterials,includingsteam,onmetalsurfacesabroadshipsthatactbychemicalordetergentactionratherthan physical contact.Mechanical (hand and power tool) and abrasive blastcleaningmethodswillbediscussedinsubsequentsections.

Unfortunately, many of the solvents routinely used for cleaning are nolonger available.Many of these solvents have been prohibited because theyareconsideredozonedepletingsubstances(ODS)orhazardousairpollutants(HAPS).Theoverviewsgivenbelowshouldguideyouinselectingamethodwhichisapplicabletothesurfacepreparationjobathand.

Solvent Cleaning (SSPC-SP 1) Solventsareliquidsinwhichanothersubstancecanbedissolved.Solventcleaningpreparesthesubstratesurfacebyremovingoil,grease,dirt,chemicalpaintstripperresidues,moisture,andotherforeignmatterpriortomechanicalcleaning or painting. This is the preferred method for removing oil andgrease.

Solvents clean by dissolving and diluting contamination to permitcontaminantstobewipedorwashedoffthesurfacewithmoresolvent.Solventsinclude organic solvents (alcohol, paint thinner, etc.), steam, detergents, andwater.

Non-Mechanical (Chemical or Detergent) Cleaning Methods

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NSTM CHAPTER 631, SECTION 5

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According to NSTM Chapter 631, organic solvents shall not be usedfor cleaning if their flash points are below 95°F (35°C).Additional safetyprecautionscanbefoundinNSTMChapter631,Volume1,Section2.

SSPC-SP1alsocoverssolventcleaning(seeAppendixF).ThisspecificationisinvokedasarequirementofotherSSPCcleaningstandardssuchasSSPC-SP10.

Procedure for Solvent Cleaning:1. Firstremovebulksurfacecontaminantswithappropriatemethod(e.g.use

awirebrushtoremovesoilandlooserust).2. Thesurfaceisthenscrubbedwithbrushesorragssaturatedwithsolvent.

Do not dip rags into the solvent—pour the solvent onto the rag—thispreventscontaminationoftheentirecontainerofsolvent.

3. Usecleanragsandfreshsolventtorinseandwipethesurfacedry.

Immersingtheworkinthesolvent,andsprayingofsolvent,arealternativemethodsforsolventcleaning.

TypicalSolventsUsed:mineralspirits,superhighflashnaphtha,butanol(n-butylalcohol),PF-145HP.Solventsbeingphasedout:1,1,1-trichloroethane,Freon(forenvironmentalreasons).

Acid Cleaning Acid cleaning is a method used to clean iron and steel by treating thesurfacewithamildacidsolution.Itcannotbeusedonaluminum,magnesium,orstainlesssteelsurfaces.

Acidcleaningremovessurfacecontaminantsbytreatingthesurfacewithaphosphoricacidsolutioncontainingsmallamountsofsolvent,detergentandawettingagent.Thismethodisnotsuitableforremovingoilorgreasefromthesurface,butitwillremovemillscale,lightrust,rustscalesandwillalsoslightlyetchthesubstratesurfaceforbettercoatingadhesion.

FourMethodsofAcidCleaning:1. WASHOFF

• Applicationoftheacidcleaner• Allowtimeforcleanertoact• Thoroughrinsing• Dryingperiodbeforepainting

2. WIPEOFF• Applicationoftheacidcleaner• Allowtimeforthecleanertoact• Wipethesurfacewithcleandampcloths• Finalwipingwithcleandrycloths• Dryingperiodbeforepainting

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3. HOTDIP• Immersionoftheworkpieceinhotacidcleaner• Rinseinhotorcoldwater• Secondrinseinweak(5%)acidsolution• Dryingperiodbeforepainting

4. SPRAY• Same steps as wash off method but requires pressurized sprayequipment.

Steam Cleaning Steamcleaningiscommonlyusedtoremoveheavydirtdeposits,soot,andgrime.Itcancausewaterbasedpaintstoswellandloosen.Additionally,itcanbe used to remove the thin film formed by corrosion preventive compound,MIL-PRF-16173,Grade1.

Typically, hotwater or steamwith pressures of between90 and100psiareused.Steamcleaningcanalsobeused inconjunctionwithnaphtha-resinsoapsolutionsandpaintremovers.Wirebrushingorbrushoffblastingmaybenecessarytocompletetheresidueremoval.

Pickling Pickling(SSPC-SP8)isamethodusedintheshoptocompletelyremovemillscale,rustandrustscalebyusingsulfuric,hydrochloric,nitric,andphos-phoric acids individuallyor incombination.Sulfuric acid ismost frequentlyused.

Pickling does not remove oil or grease. Objects to be pickled must beprewashedtoremovematerialswhichwouldpreventtheacidfromcontactingthesurfaceofthesubstrate.

Pickling can not be used on aluminum, magnesium or stainless steelsubstrates. Objects which can be pickled are also limited to the size ofthe pickling bath. Pickling is the principal method by which objects to begalvanizedbythehotdipgalvanizingprocessarepre-treated.

The roughness of the steel surface coming from a pickling bath isconsiderablylessthanthatofonewhichhasbeenfreshlymechanicallyblasted,whichmeansitispossibletoobtainlowercoatingadhesion.

Contaminants can collect on the surface of the treatment vats and cancontaminatethesubstrate.Ifcoatingadhesioniscriticalandexposureissevere,acidpicklingwouldnotnormallybepreferred.

Alkaline Cleaning Alkaline cleaning is a chemical process that requires careful controls.The most common cleaners are trisodium phosphate, caustic soda (sodiumhydroxide), and silicatedalkalis.Thesecleanersaredissolved in freshwaterand are used at relatively high temperature, 150°F (66°C), because cleaning


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efficiencyincreaseswithtemperature.

Alkalinecleanerscannotbeusedonaluminum,magnesium,stainlesssteelorgalvanizedsteel.

Alkalinecleanersattackoilandgrease,convertingthemintosoapyresiduesthat can be washed away with water. Alkaline cleaners are also effectivein removing some types of old paints by softening or lifting them from thesubstrate.

These cleaners can be applied by brushing, scrubbing, spraying or byimmersionofthesurfaceinsoaktanks.Thoroughrinsingwithfreshwaterisneededafter treatmenttoremovesoapyresiduesoralkaliwhichwill impedepaintadhesionand/orcauseharmfulreactions.

Bilge cleaning requires a significant amount of equipment and controls.AccordingtoNSTMChapter631,Volume2,Section5,ifthealkalinecleaningis to be done by the ship’s force, it shall be done only under the technicalsupervisionofqualifiedandexperiencedshipyardorindustryrepresentatives.

Detergent and Water Detergent cleaning removes oil andgrease based contaminants from thesubstrate.They allow the oil or grease contaminants to be emulsified in thewatersolutionandwashedaway.Detergentsarelongorganicmoleculeswhichhavea“fatty”endononesidethatissolubleingreaseandoilandontheothersidea“polar”endwhichissolubleinwater.Thismethodofcleaningissuitableinareaswherelocalregulationsorconditionspreventtheuseofsolvents.

A recommended detergent is MIL-D-16791, Type 1, Liquid Detergent.Several non-specification commercial products have also been usedsuccessfully.

Procedure:1. Mixdetergentinwateraccordingtopackageinstructions.2. Washsubstratesurface.3. Rinsewithfreshwater.4. Dry surfacewith air or clean dry rags to remove residualwaterwhich

couldcauseflashrusting.Ifusingcompressedair,makesureairsourceisfreeofentrainedoilormoisture.

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Method Substrate Types Typical Uses Advantages (+) and Limitations (-)

SolventCleaning Allmetals Oily/greasypartsor -Airpollutionregulations631,Section5 orsurfaces -HAZMATstorage,disposalSSPC-SP1 Dampsurfaces -Flashpoints/firehazards Initialwipedown -Healthhazard Finalwipedown -Effectsonnon-metals +Penetratessmallcrevices +Simple

AcidCleaning Ironandsteelonly Cleaningofsmallparts -Can’tuseforaluminum631,Section5 Rustremoval -Multi-stepprocess -Environmentalprecautions +Surfaceetchingpromotesadhesion +Penetratescrevicesandpits

SteamCleaning Ironalloys Tanksandvoids -Limitedshipboarduse631,Section5 Steelalloys Somepipingsystems +Cansoften/loosenoldpaint Copperalloys Removingpreservatives +Residualsaltremoved +Nochemicalsinvolved +Penetratespits +Quickremovalofdepositsonlargeareas

Pickling Ironalloys Shopuseformillscale -Shipyard/industrialuseonly631,Section5 Steelalloys removalonlargesteel -EnvironmentalandhealthprecautionsSSPC-SP8 plateshapes -Noteffectiveforoilandgrease -Can’tuseonaluminumorstainlesssteel +Completemillscaleandrustremoval

AlkalineCleaning Ironandsteel Bilgecleaning -Handlinganddisposalofsolution631,Section5 Tankcleaning -Complicatedprocedure -Can’tuseinsubmarinebilges -Can’tuseonaluminumorstainlesssteel +Moreefficient,lesscostlythansolvents +Canremovesometypesofpaint +Penetratespits

DetergentCleaning Anymetal Lightsoilandoil -Oilywaterseparatorsnoteffective Mostnon-metals removal -Noteffectiveforheavyoilorgrease +Mostenvironmentallyfriendly +Simple

Table 5-1: Summary of Non-Mechanical Cleaning Methods


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SUMMARY

Solvent, chemical, steam, and detergent/water cleaning are defined as ameans of cleaning ship surfaces prior to coating.Themethods are describedaccordingtoNSTMChapter631,Section5.

Topics• Handandpowertoolcleaning• Powertoolcleaningtobaremetal• Factorsaffectingsurfacepreparation

Scope Thissectiongetsstudentsacquaintedwithmethodsofmechanicalcleaningandwhentheyaremostcommonlyusedonships.

Learning Outcome Attheendofthissection,studentswillbeabletodiscusstheoperationalandsafetyaspectsofmechanicalcleaningtoolsandrecognizethespecificationsformechanicalcleaningmethods.

6 Mechanical Cleaning Methods

HAND AND POWER TOOL CLEANING (SSPC-SP 2 AND SSPC-SP 3)

ThesespecificationsremoveONLYlooselyadheredsurfacecontamination.They do not remove tightly adherent paint, rust, and weld spatter. Bothstandards, SSPC-SP 2 and SSPC-SP 3, only require that loose debris beremoved.“Tightlyadherent”debrisisdefinedasmillscale,rust,andpaintthatcannotberemovedwithadullputtyknife.

Handtools,coveredbySSPC-SP2,arebestusedinareaswherecorrosionisnotserious—andareespeciallyusefulinareasinaccessiblebypowertools,or for relativelysmall touch-up jobswhereabrasiveblasting isnotpractical.Powertoolcleaning,asspecifiedbySSPC-SP3, isbestusedforpreparationoflargerareas.Aswithhandtools,itismosteffectivewherecorrosionisnotserious.

The coating requirement tables at the beginning ofNSTMChapter 631,VolumeIoftencallforhandorpowertoolcleaningfor“MinimumSpotRepairSurfacePreparation.”

• Use solvent or detergent to clean area before hand tool cleaning, toremoveoilandgreasecontaminants.

• Usevacuumorproperremovalmethodstocleanupdustandparticles.DONOTDISPOSEOFDEBRISOVERBOARD!

• SSPC-VIS 3 provides comparative visual standards for hand tool andpower tool prepared surfaces. SeeAppendix E for instructions. SSPCvisual standards areusefulwhen trying todetermine if the cleanlinessrequirements of the various SSPC hand and power tool specificationshavebeenmet.

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General Safety Requirements• Usefaceshieldorgogglestoprotectfromflyingdebris.• Tapeoversharpedgedtoolswhencarryingthemaround.• Wearprotectivegloves.• Ifworkingaboveotherpersonnel,tietooltobeltorstructure.

Paint Scraper Usebypushingorpullingacrosssurface.Donotstrikesurfacewiththistool,sinceitwilldentthesurfaceandembedcontaminants.

Chipping Hammer Unlike a carpenters hammer, this hammer has a squared-off edge. Thisedgeshouldnotbesharp. It isespeciallyuseful for removingweldslagandlooseweldspatter.Thechippinghammer isusedbystriking thesurface,butonlyhardenoughtoloosenthedebris.ItshouldNEVERbeusedonaluminum,thinsteel,orpiping.

Putty Knife Putty knives can be used to determine if a coating iswell adhered to asubstrate.Donotdamagesoundcoatingsorsubstratesduringuse.

Wire Brushes Useonlightrust,afterheaviercontaminationhasbeenremoved.Ifmanybristlesarebent,thebrushwillbemuchlesseffective.Bristlesshouldnotbecontaminatedwithoilorgrease.

Wirebrushesmustalsobecompatiblewith thesubstratesonwhich theyarebeingused.Useonlystainlesssteelbrushesonaluminumorstainlesssteelsurfaces,orcorrosionwilloccurduetoembeddedparticlesofdissimilarmet-als.

Carbonsteelbrushescancausesparks.Useonlycopperalloyorstainlesssteelbrushesonsteelsurfacesifanonsparkingbrushisrequired.

Abrasive Cloths and Papers Sandpaperisveryusefulforfeatheringedgesofsurroundingintactpaint.Garnet,aluminumoxide,andsiliconcarbidearemostcommontypes.Variousgradesareavailable,rangingfrom“00”to“400”andfiner.

Non-Metallic Pads/Mats (“Greenie Pads”) Usefulforremovinglightcorrosionproducts,ruststains,andchalkingonepoxypaints.

HAND AND POWER TOOL CLEANING (continued)

BECAUSE OF THE RISK OF SURFACE CONTAMINATION DO NOT USE ON:

• Aluminum• StainlessSteel

CARBON STEEL WIRE BRUSHES

REMEMBER:

• Solventcleaning,asspecifiedinSSPC-SP1,isrequiredbeforebeginninghandorpowertoolcleaning.

• Handorpowertoolcleaningisnotasgoodasblastcleaning—lifeexpectancyofthecoatingwillgen-erallybereduced.

• AllSSPCsurfacepreparationstan-dardscanbefoundinAppendixF

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POWER TOOL CLEANING TO BARE METAL (SSPC-SP 11)

Powertoolcleaningtobaremetal,SSPC-SP11,asitsnameimplies,requirestheremovalofallrust,loosemillscaleandpainttobaremetal.Additionally,unlikeSP3,SP11requiresasurfaceprofileofatleastonemilonthepreparedsurface.Thisspecificationiscommonlyusedforspotrepairandtouch-upofdisturbedcoatingsinlieuofrequiringSP10forthesesmallareas.Becauseofthelaborinvolvedinachievingthisdegreeofcleanlinessitshouldbereservedforsmall,mildlycorrodedareasonly—timeandcostassociatedwithSP11willgoupdramaticallyastheareaandseverityofcorrosionincrease.Notethatthespecificationdoesnotspecifyamethodforachievingaonemilprofile—anymutuallyacceptabletoolsmaybeused.

009-32,Section3requiresthatthesurfaceprofilegeneratedbypowertoolcleaningtoSSPC-SP11shallbe2milsminimumforcriticalcoatedareasand1milminimumforallotherareaswhereassessable.

SomeotheradvantagesofSP11 include theability to removeor reducesharp corners and to smooth excessively rough surfaces. Vacuum shroudedtools are available to reduce dust and particles and to assist in collectinghazardousdebris.Besuretostorevacuumshroudedtoolsproperlytomaintainthebrushes.

AswithotherSSPC surfacepreparationmethods,SSPC-SP1 shouldbeusedtospecifysolventcleaningtoreducesurfacecontaminationpriortopowertoolcleaning.

Examples of power tools (Figure6-1): Rotopeen NeedleGun DiskSanders DeckAbraders

SHROUDED POWER TOOLS

• Manypowertoolsareavailablewithvacuumshroudstohelpcontroldustandallowforautomaticdebriscol-lection

Figure 6-1: Typical Power Tools


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FACTORS AFFECTING SURFACE PREPARATION

Poorsurfacepreparationisresponsibleforatleast75%ofallpaintfailures.Therearetechniqueswhichcanbeusedduringthesubstratesurfacepreparationstagewhichwillprovidebetteradhesionwiththecoating.Severalofthetopicsbelowareshowninillustrationsbelow.

Feathering the edges of old coatings (Figure6-2):• Provides smooth transition between existing paint and bare metal, topreventcrackingduetofilmshrinkagewhenpaintcures.

• Removestoplayerofalkydwhenapplyingepoxytouch-up.

Rounding sharp corners:• Allowsforappropriatethicknessoncorners.• Twotothree(2-3)mmradiusrecommended.• New coatings available, e.g. MIL-PRF-23236, TY VII High Solids,whichhaveimprovedcoverageoversharpedges.

Figure 6-2: Feathering the Edges of Old Coatings

Commercialgradepowertoolcleaning(SSPC-SP15)requiresremovalofallvisibleoil,grease,dirt,rust,coating,oxides,millscale,corrosionproducts,and other foreignmatter.Random staining shall be limited to nomore than33percentofeach9in2surfacearea,andmayconsistoflightshadows,slightstreaks,orminordiscolorationscausedbystainsofrust,stainsofmillscale,orstainsofpreviouslyappliedcoating.Slightresiduesofrustandpaintmayalsobeleftinthebottomsofpitsiftheoriginalsurfaceispitted.Inaddition,SP15requiresaminimumsurfaceprofileof25micrometers(1mil).

Rotaryimpactflaptools,needleguns,cutterbundles,hammerassemblies,and some types of sanders and grinders may be used to achieve an SP 15cleanlinesslevel.

SP 15may be used if approved byNAVSEA technical authority on thebottoms of pad eyes (tie-downs) only ifwaterjetting is used as the primarymethodofsurfacepreparation.

COMMERCIAL GRADE POWER TOOL CLEANING (SSPC-SP 15)

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Smoothing irregular weld seams and spatter:• Grindweldsandweldspattersmoothtoprovideflatsurface.• Coatingswillnotcoversharporporousweldsplattereffectively.

Weld slag removal:• Weldslagandoxideswillhavelowadhesionandcouldcausecrevicesandvoidswhichmaycausepaintfailure.

Scuff sanding of intact paint:• Providesforgreateradhesionoftopcoatbyrougheningthesmoothsur-faceofexistingtopcoats.

Thischapterhasdescribedusinghand-andpower-toolcleaningasasurfacepreparation method. Hand tools (SSPC-SP 2) are best used in areas wherecorrosion is not serious. Power-tool cleaning (SSPC-SP 11) is used for spotrepair and touch-up of disturbed coatings in small areas. Commercial gradepower-tool cleaning (SSPC-SP 15) may be used if approved by NAVSEAtechnicalauthorityonthebottomsofpadeyespriortowaterjetting.Feathering,roundingsharpcorners,smoothingirregularweldseamsandremovingslag,andsandingintactpaintcanallassistinbettersurfacepreparation.

SUMMARY


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