esab ship building by svetsaren 2003

7/30/2019 ESAB Ship Building by Svetsaren 2003

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THE ESAB WELDING AND CUTTING J OURNAL VOL. 58 NO.1 2003

SHIPBUILDING


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C ontents Vol. 58 No. 1 2003

Articles in Svetsaren may be reproduced without permission but with

an acknowledgement to ESAB.

Publisher

Bertil Pekkari

Editor

Ben Altemhl

Editorial committee

Bjrn Torstensson, Johnny Sundin, Johan Elvander, Lars-Erik Stridh, L ars-G ran Eriksson,

Dave M eyer, Tony Anderson, P eter Budai, Arnaud Paque, K laus Blome

Address

SVETS AR EN, ESA B AB, M arketing Communication

c/o P.O . B ox 8086, 3503 RB Utrecht, The Netherlands

Internet address

http://www.esab.com

E-mail: info@ esab.se

Lay-out: D uco M essie, printed in the Netherlands

THE ESAB WELDING AND CU TTING JO URN AL VO L. 58 NO.1 2003

Photo courtesy Stocznia Szczecinska

Nowa, Poland. The Bow Sun, the worlds

largest dup lex chemical tanker. The

FCAW of a series of these tankers w ill becovered in the next issue of Svetsaren.

New developments within the Aluminium

Shipbuilding Industry

Recent developments in the construction offast patrol and transportation vessels for theU S milita ry by B ollinger/Inca t Inc., applyingthe latest higher strength varieties of the5083 aluminium marine alloy.

FSW possibilities in Shipbuilding

ESA B LE G IO TM friction stir weldingmachines expand the scope of application o faluminium in shipbuilding b y providingaccurate welded components that requireminimal fit-up work, and by allowing the useof high strength aluminium grades that wereformerly regarded as un-weldable.

Efficient production of Stiffeners for

ShipbuildingE SA B s new I T-100 aut oma tic T-bea m weld-ing machine offers highly productive, auto-mated welding in an unmanned productionenvironment to shipbuilders and other fabri-cators with a need to produce beams.

ESAB Railtrack FW 1000 aids fabrication

efficiency of t he worlds largest aluminium

yacht

Mechanised MIG welding with Ra iltrackFW 1000 for horizonta l and vertical butt

welds has greatly improved the welding effi-ciency in the building of the worlds largestalumium yacht at R oyal H uisman, TheNetherlands.

How much heat can various steels and

filler metals withstand?

The art icle reports on research into t he maxi-mum heat input acceptab le for high tensileconstruction steels.

ESAB Brazil provides BrasFELS shipyard

with extra FCAW productivity for offshore

vessels

The B rasFEL S shipyard, in Angra dos R eis,Brazil, increases welding productivity withOK Tubrod 75 ba sic cored w ire for low -tem-perature applications.

Secure downhill MAG welding of butt - and

fillet welds with ESAB OK Tubrod 14.12The a rticle reports on highly prod uctivedow nhill welding procedures used by G ermanshipyard s for t hin-wa lled applications usingOK Tubrod 14.12 metal-cored wire.

Thermal Bevelling Techniques

The article discusses the thermal bevellingtechniques ava ilable from ESA B , highlightingseveral cutting processes and a variety ofplate edge preparation applications.

Stubends & Spatter

Short news and product introductions.

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The creation of this article was promoted by currentactivities within the U nited Stat es military, the extraor-dinary developments in aluminium shipbuilding that

have been taking place in Australia, and the creationof new high strength aluminium alloys, primarily inE urope, for t he shipbuilding industry.

I w as fortunate enough recently to visit Incat TasmaniaPty Ltd. (Shipbuilding) off the southeast coast ofAustralia. This manufacturer has over the years takenaluminium shipbuilding to exciting new levels. In 1977they launched their first high-speed catamaran, andtoda y they are ma nufacturing the new generation of 98-metre (100 plus yards) wavepiercers that are being eval-uated by the U nited States military (see figure 1).

Incat has constructed more than 50 vessels of varyinglengths. The companys first passenger/vehicle ferry wa sdelivered in 1990, a 74-metre Wave P iercing Ca tamaranwith a maximum deadweight capacity of 200 tonnes.

The more recent 98m Evolution 10B range has a dead-weight four times that amount. While Incat-built ferriesinitially revolutionized transport links around the

United Kingdom, today its ships operate in North andSouth America, Australasia, the Mediterranean, andthroughout greater Europe. Incats extensive shipbuild-ing activity is conducted from a modern facility withover 32,000 m2 under cover, located at Hobarts Princeof Wales Bay Tasmania.

Aluminium Welded S hips Within The UnitedS ta tes Milita ry.

In response to great interest from the U S military inhigh-speed craft, a strategic alliance has been formed

between I ncat, the premier builder of the worlds fastestvehicle/passenger fe rries, and B ollinger, a provenbuilder of a variety of high speed, reliable a nd efficientpatrol boats for the U S Navy and Coast G uard.

Svetsaren no. 1 2003 3

By Tony Anderson - Technical Services Manager - AlcoTec Wire Corporation

The article describes recent developments in the construction of fast patrol and

transportation vessels for the US military by Bollinger/Incat Inc., applying the latest

higher strength varieties of the 5083 aluminium marine alloy. The section on weld-

ability addresses the open-end questions that surround these very new alloys.

New developments w ithin the

Aluminium Shipbuilding Industry

Figure 1. The Spearhead - new generation of 98-metre wavepiercers


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The U S government has awarded B ollinger/Incat U SAthe charter for a High Speed Craft (HSC) for a multi-service program operated by va rious arms of the U Smilitary. The HSC Vessel, now known as Joint VentureHSV-X1, is being used for evaluation and demonstra-

tion trials in order to assess the usefulness of such tech-nology in U S military and C oast G uard applications.Ano ther charter, the U SAV TSV-1X Spearhead is the U S

Armys first Theat er Support Vessel (TSV) a nd is part o f

the A dvanced C oncept Technology D emonstrator

(ACTD) program by the Office of the Secretary ofD efense and the U S A rmy. TSVs promise to change theway the US Army gets to the fight by allowing person-nel to quickly deliver intact packages of combat-readysoldiers and leaders with their equipment and supplies.

Another order, from Military Sealift Command,

Washington, D .C., calls for the lease of a 98m craftfrom B ollinger/Incat U SA, L LC , Lockport, La., tosupport US Navy Mine Warfare Command. The shipwill be capable of ma intaining an a verage speed of 35knots or greater, loaded w ith 500 short t ons, consistingof 350 personnel and milita ry eq uipment, have a mini-mum operating range of 1100 nautical miles at 35knots, and a minimum transit range of 4000 nauticalmiles at an avera ge speed of 20 knots. The craft will becapable of 24-hour operations at slow speeds (3-10knots) for small boat and helicopter operations.

New Developme nts in High S trengthAluminium Alloys for Marine Applications

Until fairly recently, the most popular base materialused for a luminium shipbuilding, 5083, has had very lit-tle rivalry from other alloys. The 5083 base alloy was

first registered w ith the Aluminium Associat ion in 1954,and while often referred to as a marine aluminium alloy,has been used for many applications other than ship-building. The popularity of the 5083 alloy within theshipbuilding industry has been largely ba sed on its avail-ability and also its ability to provide an a luminium alloywith excellent strength, corrosion resistance, formabili-ty and weldability characteristics. Other lower strengthalloys, such as 5052 and 5086, have been used for themanufacture of usually smaller, lower stressed and typi-cally inland lake boats, but 5083 has been predominantin the manufacture of ocean-going vessels.

In recent years, progress has been achieved by alu-minium producers in the development of improvedaluminium alloys specifically ta rgeted a t the shipbuild-ing industry. In 1995 the aluminium manufacturer,Pechiney of France, registered the aluminium alloy5383 and promoted this material to the shipbuildingindustry as having improvements over the 5083 alloy.These improvements provided po tentia l for significantweight savings in the design of aluminium vessels andincluded a minimum of 15% increase in the post-weld

4 Svetsaren no. 1 2003

Figure 2. GMAW being used on high strength large aluminium structural components at

Incats Shipyard in Aust ralia


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yield strength, improvements in corrosion propertiesand a 10% increase in f at igue strength. These develop-ments, coupled with formability, bending, cutting, andweldability characteristics, at least equal to that of5083, made the 5383 alloy very attractive to designersand manufacturers who were pushing the limits to pro-duce bigger and faster aluminium ships.

More recently in 1999, the aluminium manufacturer,Co rus Aluminium Walzprodukte G mbH in Koblenz(G ermany), registered the aluminium base alloy 5059(Alustar) with the American Aluminium Association.This alloy w as a lso developed as a n ad vanced materialfor the shipbuilding industry providing significantimprovements in strength over the traditional 5083alloy. The 5059 alloy is promoted by Corus as provid-ing improvements in minimum mechanical propertiesover a lloy 5083. These improvements a re referenced asbeing a 26% increase in yield strength before weldingand a 28% increase in yield strength (with respect toallo y 5083) af ter w elding o f H 321/H 116 temper pla tesof the AA5059 (Alustar alloy).

Welding the New Aluminium Alloys

The welding procedures used for these high strengthalloys are very similar to the procedures used whenwelding the more traditional 5083 base alloys. The5183 filler alloy and the 5556 filler alloy are both suit-able for welding 5383 and 5059 base alloys. Thesealloys are predominantly welded with the G MAWprocess using both pure argon and a mixture of

argon/helium shielding gas. The ad ditio n of helium ofup to 75% is not uncommon and is useful when weld-ing thicker sections. The helium content provides high-er heat during the welding operations, which assists incombating the excessive heat sink when welding thickplate. The extra hea t a ssociated with t he helium shield-ing gas a lso helps to reduce poro sity levels. This is veryuseful when welding the more critical joints such ashull plates that are often subjected to radiographicinspection.

The design strength of these alloys are available from

the material manufacturer, however, there wouldappear to be little as-welded strength values incorpo-rated in current welding specifications. Certainly theserelatively new base a lloys are not listed materials with-in the AWS D 1.2 Structura l Welding C ode Aluminium, and consequently no minimum tensilestrength requirements are included in this code. If thismaterial continues to be used for welded structures,there will be a need t o a ddress this situation by estab-lishing appropriate tensile strength values and toinclude them in the appropriate welding codes.

Early testing on the 5059 (Alustar) base alloy indicat-ed tha t problems could be encountered relating to t heweld metal being capable of obtaining the minimumtensile strength of the base material heat affectedzone. One method used to improve the weld tensilestrength was to increase the amount of alloying ele-ments drawn from the plate material into the weld.This was assisted by the use of helium additions to theshielding gas, which produces a broader penetrationprofile that incorporates more of the base material.The use of 5556 filler alloy rather than the 5183 fillercan also help to increase the strength of the depositedweld material.

Obviously these high performance vessels req uire highquality welding. The training of welders, developmentof appropriate welding procedures, and implementa-tion of suitable testing techniques are essential in pro-ducing such a high performance product.

The future

With the increasing demand to create larger and fasterships, particularly for military service, and the develop-ment of new improved, high-performance aluminiumbase materials, it is apparent that aluminium weldinghas acquired an interesting and important place withinthe shipbuilding industry. A lso, with t he pending intro-duction of this unique technology into the U nitedStates, it is important that designers, manufacturers,and pa rticularly welders and welding engineers are ade-quately trained and familiar with this new technology.


About The Author:

Tony Anderson is Technical Services Manager ofAlcoTec Wire Corporation, MI, USA, Chairman ofthe Aluminium Association Technical AdvisoryCommittee on Welding and Joining, Chairman ofthe American Welding Society (AWS) Committeefor D 10.7 G as Shielded A rc Welding of A luminiumPipe, Cha irman of the AWS D 8.14 Co mmittee forAutomotive and Light Truck Components WeldQuality - Aluminium Arc Welding and ViceChairman of the AWS Committee for D1.2Structural Welding C ode - Aluminium.


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Ass embly w ork ha s never been ea sierImagine if a large catamaran could be constructedfrom building blocks, just like a toy boat. All pieceswould fit perfectly to ea ch other and dimensional accu-racy and changes could be mastered to full degree.Friction Stir Welding takes the first step towards suchassembly work in shipbuilding. D ue to the low heat-

input during joining and resulting very low residualstresses, the welded components are accurate and min-imal fit-up work is needed. The resulting savings inboth time and money are obvious. Since this createscompetitive advantage to the users of FSW pre-fabri-cates, documented information of actual savings is notvery often reported. However, Midling et. al. 2000,gives an idea of the possibilities gained by friction stirwelded pre-fabricated panels from a panel producerspoint of view:

Industrial production with a high degree of completion.

Extended level of repeata bility ensuring uniformlevel of performance, qua lity a nd narrow tolerances.

The flexible production eq uipment a nd ca pacity allowscustomer built solutions with reliability of delivery.

The completed panel units are inspected andapproved at present by classificat ion autho rities suchas D NV, RI NA and G ermanischer Lloyds.

The high level of stra ightness of the pa nels ensure easyassembly at ya rd, which means less manual welding.

Supplementary wo rk for the customer, such as lessneed for floor levelling and preparation for floor cov-erings also is a ma jor cost saving with FSW panels.

What is gained after the welding?One of the most attractive features of friction stir

welded products is that they are ready-to-use. No timeconsuming post-weld treatment such as grinding, pol-ishing or straightening is needed. With proper designthe elements are ready-to-use directly after welding.However, it is important to keep in mind that designswhich are made for MIG or TIG welding, are not nec-essarily suitable for friction stir welding. The limitingfactor often being the relatively high down-force need-ed when friction stir welding. A proper support in aform of backing bar or design change are often needed(Figure 2). Once done, repeat ab ility rea ches levels pre-viously not experienced in welding.


By: Kari Lahti, ESAB AB Automation, Gothenburg, Sweden

Aluminium is increasingly being recognised as an alternative, weight-saving

construction material in shipbuilding. Friction Stir Welding expands the scopeof application of this material by providing accurate welded components that

require minimal fit-up work, and by allowing the use of high strength aluminium

grades that were formerly regarded as un-weldable. ESAB LEG IO modular

friction stir welding machines bring this new welding process within reach at

moderate investment costs. H ere we discuss the main benefits of friction stir

welded aluminium components in ship structures.

FSW possibilities in Shipbuilding

Figure 1. Friction stir welded, straight panels under inspection

at ESAB FSW Center of Excellence in Sweden.

Figure 2. Designs suitable for friction stir weld ing of 2- skin

profiles in aluminium. Illustration: ESAB


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When producing large surfaces like walls or floors,

besides the straightness of t he panels, also the resulting

reflections are an important and expensive issue to

consider. A lot of time is spent polishing and " making-

up" surfaces which are architecturally visible. In FSW

prefab ricated pa nels, the reflections are merely caused

by the surface appearance of the aluminium plates and

profiles in the as-delivered state, not by the reflectionscaused b y w elding heat input.

Why use aluminium instead of steel?

One excuse of not using aluminium has always been

" that it is not as strong as steel." True and no t true. It,

of course, depends also on the a lloy to be used, and sur-

prisingly enough, there are a luminium alloys which are

as strong or even stronger tha n steels. For example the

so called " AL U STAR " has yield and tensile strenghts

comparable to low-alloyed steel S235. AlCu4SiMg(AA2014) an alloy typically used in aerospace appli-

cations has siginficantly higher strength than alloys in

5xxx- and 6xxx series which are typically used in ship-

building. Some of these alloys just have no t been used

in shipbuilding before, due to t heir poor welda bility!

With friction stir welding, some of these barriers can be

overcome just imagine, for example, using strong

alloy A A7021 for ma king aluminium floor panels even

thinner, and gain weight savings by " thinking different-

ly" . In Figure 3 the welda bility of various aluminiumalloys is shown a s a reminder. The typica l alloys used in

shipbuilding are from 5xxx series due to their good

corrosion resistance, or from 6xxx series due to the

strength. A dissimilar combination between these two

alloys is of course also possible (Larsson et. al. 2000).

An easy way to make small-scale pre-fabri-

cated panels or components

Figure 4 gives an idea of relatively easy implementat ion

of FSW in shipbuilding. ESA B s new LE G IO con-cept is ideal for fabrication of small batches of friction

stir welded panels. The equipment is placed on the

workshop right next to the a sembly of the shiphull. The

picture is from Estaleiros Navais do Mondego S.A.

Shipyard in Portugal. Even small batches can effec-

tively be w elded on-site.

The LE G IO concept represents a modular, modern

design available for friction stir welding. A series of

standardised welding machines puts FSW at every-

ones reach. Welds with highest quality are producedeven in small ba tches. Tab le 1 summarises the ra nge of

machines available in the LE G IO system. A size " 3"

should cover the needs of most shipyards.


Figure 3. Weldability of d ifferent aluminium alloys. TWI.

Figure 4. FSW LEGIO 3UT installed next to shiphull

prod uction line at Estaleiros Navais do M ondego S.A.

Shipyard in Portugal.

Figure 5. Hat pro files stacked fo r shipping . Definitely no

straightening needed after the w elding process.

Photo: Hydro Aluminium.


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Table 1. The family pictu re of the new modular LEGIO family for easy imp lementation of friction stir weld ing.

Size Vertical Spindle AA 6000 AA 5000 AA 2000 CU

downforce effect AA 7000 (oxygen free)

FSW 1 6 kN 3 kW 3 mm 2 mm 1.5 mm 0.8 mm

FSW 2 12.5 kN 5.5 kW 5 mm 3.5 mm 2.5 mm 1.5 mm

FSW 3 25 kN 11 kW 10 mm 7 mm 5 mm 3 mm





How to proceed?

Friction St ir Welding is much easier to implement thanmost other welding processes. The welding operatordoes not need any special skills, since the parametersare repeata ble and high quality is easily achieved t ime

after time. You dont need to be big and powerful toinvest in Friction Stir Welding the modular way. Itmay, however, make You big and powerful by shorten-ing cycle times and improving the quality of Yourproducts. Just dare to do it!

References:

Larsson H., Karlsson L., Svensson L-E, 2000. FrictionStir Welding of AA5083 and AA6082 Aluminium. In:Svet saren 2(2000). 5 pp.Midling O .T., Kv le, J.S. 1999. Ind ustrialisation of thefriction stir welding technology in panels production

for the maritime sector. In: The 1st InternationalSymposium on Friction Stir Welding. Thousand O aks,C A, U SA 14-16 June. 7 pp.

About The Author:

Mr. Kari Erik Lahti graduated from HelsinkiU niversity o f Techno logy, Finland , 1994 with aM.Sc. degree in welding technology. After workingas a research scientist in the field of welding meta ll-lurgy, he joined Oy E SAB in Finland 1997 and star-ted a s product manager for welding automation.In 1998 Ka ri Lahti finalised his Ph.D . in " nominalstress range fatigue of stainless steel fillet welds"Since 2002 he has been working at ESAB ABG teborg, Sweden, currently as marketing mana ger

for advanced engineering products.


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1. Introd uction

ESAB has marketed and distributed robust, manualT-bea m welding eq uipment for ma ny yea rs, equipmentdesign generally following market demand. Although,a t ypical T-bea m welder w as part ly mechanized, all set-tings of the welding machine had to be carried outmanually by a n operator due to its prescribed weldingprocedures. Therefore, the design and cont rol technol-

ogy o f such machines is fairly simple, relying heavily onhighly skilled opera tors to pro duce parts of consistent-ly high qua lity.

Many companies, especially shipyards, are experienc-ing increasing competition from ma ny other wo rldwideoperating enterprises. To survive, in an often toughand continuously shrinking market, shipyards mustnow find new ways to increase their internal produc-tivity. One way to increase productivity is to increasefactory automation. Production equipment whosedesign provides the factory with a higher degree of

automation also increases efficiency and quality levels.

For example, modern control technology makes it alsopossible to schedule tighter production runs by pre-setting the production equipment with instruction setsimportant for unmanned operation. The control sys-tem can also be connected to an internal MR P systemfor even more eff icient prod uction efficiency.

As suppliers of state-of-the-art welding equipment,ESAB has seen an increasing demand for more sophis-ticated production systems equipped with the latest con-

trol technology. To meet this demand, E SAB has devel-oped a n automated T-bea m welding system, which canbe used in a n unmanned production environment.

2. Eq uipment for T-bea m P rod uction

Situated upstream a nd do wnstream of the T-beam w eld-ing machine there are a number of material handlingequipment cells, including:

In-feed conveyor usually situated after a cuttingmachine.

G rinding and shot-blasting equipment.

Web raising station. Web alignment station upstream to the T-beam

welder. T-beam welder with peripheral equipment. Out-feed conveyor with raising/lowering capability. C oo ling b ed . Straightening equipment. Shot-blasting equipment. P riming boo th. Cutting equipment for notches and holes. Centralized control system.

Modern production equipment needs to be flexible towork efficiently in an automated environment. It istherefore of great importance to be able to integratethese work cells into a centralized computer system,which is then able to communicate with mod ern infor-mation systems (e.g. MRP ).

2.1 In-feed conveyor

The bea m welding system beco mes more productive ifthe beam is supported and conveyed through themachine in a very precise manner. In other words, theprecision of the in-feed conveyor will directly affect

the precision of the f inished bea m (Figure 1).A raising station situated upstream of the in-feed con-veyor will place the w eb in the middle of the flange a nd


By Herbert Kaufmann, ESAB AB, Welding Automation

ESABs new IT-100 automatic T-beam welding machine offers highly pro-

ductive, automated welding in an unmanned production environment to

shipbuilders and other fabricators with a need to produce beams.

O ptimum welding speed, beyond 1m/min., is provided by double-sided

tandem submerged arc heads. Web and flange are automatically longi-

tudinally centered in the in-feed conveyor, whereas on-line straightening

of the beams is provided by inductive heating, avoiding time-consuming

post-weld straightening procedures.

Efficient production of Stiffeners for

Shipbuilding


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then feed it into the in-feed conveyor. The beam thenstops after it passes through the first set of the verticalfeed rollers. The flange width will be measured and itsdimension will be tra nsferred to the controller of t hebeam welder.

Even if the measured flange width differs along thebeam length, centering the web exactly on the center

of the flange now becomes easier. If the measureddimension of the flange is out of tolerance an alarmwill sound and then the operator can d ecide if the tar-get beam should be welded or not.

B efore rea ching the T-beam welder, longitudinal cen-tering adjustment of the web and flange has been com-pleted after the beam ha s passed through all three pairsof rollers. T-beams with a positive or negative value canbe produced even though the offset defaults to zero .

The tra verse speed of the in-feed co nveyor is synchro-

nized with the beam w elding speed, which is contro lledby the T-beam welder.

2.2 T-beam welder

The new ly developed IT-100 Auto matic T-bea m weld-ing machine has been optimized for the production ofsymmet rical T-bea ms. With small mod ificat ions, themachine will weld other types of profiles and beams(Figure 2).

All pre-set va lues for t he T-bea m welder, for exa mple,of the b eam sizes and associated w eld parameters canbe made by t he operator or obt ained from a customersproduction planning system. It is therefore possible torun the T-beam line with mixed production schedulesof va rying sizes of T-bea ms, without interrupting theongoing production.

Severa l features of the new I T-100 Automa tic arewo rth mentioning. With t he I T-100 Auto mat ic, beam scan now be welded without having to tack weld theweb and flanges. Another important improvement isthe a utomatic centering feature w hich a lways positionsthe web into the center of the flange even if the flangewidth varies. Also, welding 5 mm from the start andthe end of the T-bea m guara ntees efficient utilizationof T-bea m mat erial for the finished beam.

The systems main controller is an Allan Bradley PLCtype Control Logic 5550. Internal communication isvia a D eviceNet bus. All external devices are linked tothe controller by an Ethernet bus system. The con-troller also uses a modem for remote supervision, tomake programme alterations, and to become assess-able for service diagnostics from the outside. Installa-

tion and specific production parameters (weldingparameters and work piece dimensions) can beentered from the operators panel (Panel View 600).The operator can protect all settings with passwords.

The controller is also equipped with a built-in qualitymonitoring system. Parameters such as axis position,weld speed, voltage and current deviations are contin-uously monitored. Ala rms will sound if parameters areoutside predetermined limits.

B y tracking the consumption of consumables (wire andflux) the IT-100 Automatic will generate an alarm ingood time before new wire or flux needs to be loa ded.


Figure 1 . Infeed conveyor, front view.

Technical data:

Lengt h of infeed conveyor 6000 mmH eight of conveyor 720 mmWeight 6 tonsNo of f lange/web rollers tota lly 6 (3 pairs of rollers)R apid speed max. 16 m/min

Figure 2. ESABs T-beam welder IT-100 Automatic.

Technical DataWidth of Flange 102 600mmThickness of flange 10 41mmH eight of Web 150 915mmThickness o f Web pla te 6 25mm


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2.3 Platform

To save space all essential components have been placed

on a platform located over the T-beam welders and pa rts

of the in-feed conveyors. The corresponding span is

appro ximately two pa rallel T-bea m lines (10 x 8 Meters)

(Figure 3).

Essential components include control cabinets, a fluxfeeding system, and the hydra ulic power unit and cool-ing units. Additional space is also available on this

platform for storing flux and wire. All cables includingmain power connections are installed in cable traysunderneath the platform. Fences surround and guardthe platform area which is accessible only through twosets of stairs.

3 Be a m s tra ightening method s

Another important feat ure in E SAB s new T-beamwelding line is the ab ility t o prod uce straight T-bea mswith a high degree of precision a nd repeata bility w ith-out utilizing a post-weld straightening procedure.Any necessary stra ightening process is done during the

welding phase and, therefore, subsequent manualstraightening procedures are unnecessary.Due to the heat input from the welding process, thefinished beam will have a certain positive camber(bow). Without ESABs straightening process a typicalcamber f or a 16m long beam w ould be betw een 60 and100mm, depending on t he amo unt of hea t input duringthe welding process. Corrective straightening opera-tions afterwards will most likely adversely affect thebeams accuracy and straightness and possibly intro-duce other residual stresses in the beam.Cutting notches or holes into the beam after thestraightening process will affect the straightness of thebeam, again because of the release of some of theremaining stress in the beam section.

There are different production methods used to pro-duce straight beams. In the following section there arefour different straightening methods discussed.

3.1 Mechanical Flange straightening

Manual operation requiring a special machine. Must be done by skilled operators.

Time consuming process. Cannot be done during welding. R isk of buckling distortion in the web. Many types of distortion phenomena can b e corrected.

3.2 Manual Flame straightening

D ifficult to achieve high accuracy. Time consuming process. U se of water after welding causes corrosion prob-

lems in subsequent operations. Must be done by skilled operators. Many types of distortion phenomena can be cor-

rected.

3.3 Flame straightening with Propane burners

mounted to the T-beam welder (Figure 4)

Heated simultaneously during welding. D ifficulty predicting heat input. Manual setting of heat input. Poor repeatability. D istortion in only one dimension can be corrected

(Camber).

3.4 Induction line heating straightening

B oth mechanical and thermal straightening techniquesare used to stra ighten beam s subjected to plate shrink-age. Mechanical straightening requires large, expen-sive machines, which produce process wrinkles . Aswith t hermal straightening, this technique ad ds anot h-er step to the beam production line.

Thermal straightening requires that the opposite(upper) side of the beam is heated which later

induces a compensating shrinkage. This is supposed tocompensate for the initial shrinkage induced duringthe welding process mentioned above a nd can be d onewith Propane burner heating (see 3.3). The use of


Figure 3. Platform for storage of peripheral equipment.

Figure 4. ESABs T-beam welder IT258 w ith Propane torch

heating/straightening.


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induction heat ing equipment (Figure 5 + 6) offers sev-eral advantages:

The concentrated heating produces a higherstraightening effect.

Less risk of overheating the surface. No noise. D irect heating of the beam produces less heating of

the environment. No toxic fumes. Heat input is controlled. G ood temperature control. Excellent repeatability. Heat input can be set automatically

(programmable).

Induction heating is easy to adapt to an existing line.The required power for an induction heating systemfor larger T-beam production is approximately 60 to100 kW (E FD :s Minac 60 or 100 D ual system). The useof a D ual system (with tw o coils) is recommendedwhere one heating coil is used simultaneously on eachside of t he Web.

By balancing the power input at Curie temperature,this system can be, self-regulating . The rapid hea tingallows the thermal straightening to be done at the sametime as the welding providing a one-step productionprocedure. This is very cost eff ective due to substantialreduction in manpower and energy consumption.

When an a lternat ing current flow s through a coil, eddycurrents are induced in a meta l object placed inside thecoil. Heat is developed where these eddy current flows.

On the other side of the T-bea m an identica l inductioncoil with guide rollers heats the hub.

4. Welding P roc es s

The IT-100 submerged-arc welding (SAW) configura-tion uses two single wires (D C+ AC ) on each side ofthe web (Figure 7). The torch a rrangement uses a lea d-ing DC wire and a trailing AC wire. Offset between the

wires is 12 mm. Power sources include the LAF 1250and TAF 1250. The welding controller is an AllanB radley PL C t ype Control Logic 5550

4.1 Welding Equipment

The power sources proposed for this application arethe L AF 1250 D C power source and the TAF 1250 AC(square wa ve) power source.The welding system includes ESA B s well-proven a ndreliable A6 components. Each of the welding torchescan be adjusted in three dimensions using slides andscales for accurate set-up. Wire drums (365 kg) are

placed on the platform above the beam weldingmachine. All wire feeders and wire straightening set-tings are also eq uipped with scales for ea sy adjustmentafter changing wire.

Figure 5. Induction heating principle.

Figure 7. DC-AC Torch arrangement in ESAB s T- beam welder.

Figure 6. Induc tion co il with guide ro llers during heating for

straightening of T-beams.

4.2 High speed SAW welding

Weld undercuts and arc blow due to welding at highercurrents are often the limiting factor for weldingspeed. In most situations multiple wires allow elonga-tion of the arc heat source to enable faster weldingwithout undercuts. To avoid or reduce arc blow, thebest solution is a tandem welding arrangement using aleading DC and a trailing AC torch.

Weld speeds above 1 m/min can b e easily achieved . Forhigh speed quality welding, it is also important to weldon clean plates free of mill scale and rust. Shot blastingor grinding of all original pa rts is essential (Figure 8).


13/44

5. Theo retica l a na lys is of the d is tortion a fterw elding a symme trica l T-bea m

The intense heat input from the welding process andthe molten steel, which is deposited into the joint, con-tribute to thermal expansion and contraction of theheated parts. Also residual stresses released in therolled and raw -cut materia l will have some influence onthe final shape of the beam.If the welding is done on only one side of the web theplate will bend upwards and sideways (sweep and cam-ber). If tw o welds are done simulta neously, one on eachside of the web, the beam tends only to exhibit beam-camber due to the shrinkage produced after welding.

D istortion can be minimized in symmetrical designs byapplying the heat into the material in a symmetricalmanner. The remaining distortion o n the final par t canrarely be tolerated in subsequent assemblies and mustbe eliminated with thermal or mechanical methods(see part 3 above).

5.1 Type of distortion in symmetrical T-beams:

Camber:

Bending distortion produced by longitudinal shrinkageupwards. C an b e neutralized b y a pplying similar heatinput as during the w elding process into the upper pa rt(above the neutral a xis) of the T-bea m.

There are different method s to calculate the size of thecamber. With modern C AD systems, mathematical

and thermal problems can be modeled easily. Thebiggest challenge is to determine the heat transfer andthe a ssociated distribution in the b eam t hat is neededas input for the calculation. Traditional methods ofdetermining the size of the camber use establishedbeam bending theory (within the elastic range of dis-tortion) where the beam is exposed to compressiveforces and torq ue on each end of the beam:

(1) = M x L2 /8 x E x L = P W x b x I 2 /8 x E I

Where = Camber in mm.P W = Shrinking force in N.L = length of beam in mm.E = modulus of elasticity in N/mm2.

I = moment of inertia in N/mm4.

b = distance from flange to neutral axis.

Shrinking force P m per mm2 for different weldingmethods has been determined by Malisius (see refer-ences below). Typical shrinking forces for fillet weldsare 6300 N/mm2

With this formula, an a pproximate camber va lue can beeasily calculated. For a beam web size, flange size, andtotal length of 475 x 13mm, 125 x 25mm, and 16m,respectively, a resultant camber of 53mm is calculatedassuming a fillet weld on ea ch side (leg length = 8mm).

The result in this case seems to be too small comparedwith empirical data found in the field. The differencecan perhaps be explained by considering additionalforces associated with the shrinking effect of theflange. One effect could be a ttributed to t he tempera-ture difference between the w eb and the flange meas-ured at the welding site. The temperature differenceseems to be the reason why the flange (but not theweb) length increases by l during welding. The heatwill enter into the flange much faster than the Web

because the cross sectional area of the flange is muchsmaller than the webs.


Figure 8. Cross section o f welded T-beam.

I

0.3 mm /m

Figure 10 . Elongation of flange during welding

P a x P a x

I

(2) l = T x x l

if T = 30 degrees, = 11,7 x 10E -7 and l= 16m then is l= 5.3mm

Shrinking force P ax which will reduce the beam lengthby l

(3) P ax = A x l/l x E (H ookes law)

If A = area of fla nge 125 x 25mm = 3125mm2 and E =210 MN/m2. With the known figures the shrinking forceP ax= 220000 NFigure 9. Camber.


14/44


However, it is difficult to determine the temperature

difference T. An a verage t emperat ure must be used

as the temperature distribution in the flange depends

on the mass ratio between the web and t he flange.

The total shrinking force becomes:

P = P w + P ax = 403200 + 220000 = 623 kN

B y using formula (1) again the tota l camber now

becomes 82 mm. This is more in line with the empirical

results.

Sweep:

B ending distortion due to longitudinal sidewa ys

shrinkage caused by unsymmetrical welding hea t input

(e.g. different weld parameters in fillet welds or big

longitudinal offset between torches).

The sideways sweep phenomenon can be calculated in

a similar wa y, but its associat ed shrinking force must be

determined experimentally. It is important to limit un-

symmetrical heat input to the beam and also to make

sure tha t the w eb is centered and perpendicular to the

flange (Figure 11).

Perpendicularity between web and Flange:Perpendicularity deviations are usually caused by

using different weld parameters for fillet welds or from

big longitudinal offset between torches (Figure 12).

Angu lar Change (of flange) in fillet weld :

Caused by different temperatures between top and

bottom of flange. Bending distortion caused by trans-

versal shrinkage sideways and upwards (Figure 13).

R elease of R esidual stresses from previous heat treat-

ment a nd rolling operations:

Residual stresses contained in the raw sheet material

due to milling and cutting operations will have anunpredictable impact on the straightness of the fin-

ished part. It will particularly influence the repeatabil-

ity of the straightening process.

s 0.9mm/m

Figure 11. Sweep .

d= 1.5 /100 x b

Figure 12. Perpend icularity.

Figure 13. Angular Change.

Reason

Bending distortion by longitudinal shrinkage upwards.

Bending distortion by longitudinal shrinkage upwards.

Unsymmetrical heat input from the welding process

(different weld parameters in fillet welds. Big longitudinal

offset between torches).

D ifferent weld parameters in fillet welds, big longitudinal

offset between torches.

C aused by different temperatures between top and bot-

tom of flange. B ending distortion by transversal shrinkage

sideways and upwards.

R eleasing of residual stresses from earlier heat treatment

and rolling operations of raw material.

Measure

C an be neutralized by applying heat ontop of the T-beam (see point 3 above).

Perpendicularity (see below) needs to be

corrected.

C hange setting of weld parameters and

reduce offset of torches.

C hange weld parameters and reduce

torch offset.

Use mechanical "pull down" straightening

feature of T-beam welder.

Use heat treated material, use cutting

process with lower heat input.

Type of distortion

Camber

Sweep

Perpendicularity

(betw een Web a nd

Flange)

Angula r cha nge

(of flange)

Release of residual

stresses

c 0.5 x b/100

Summary of all types of beam distortions


15/44

5.2 Straightening by line-heating

By applying heat to the top of the beam during thewelding process it is possible to produce stra ight bea ms(see point 3.4). The theory behind this is to achieve abalance between the heat applied by the weldingprocess (below the neutral a xis of the T-bea m) and bythe heat applied by the proposed straightening process(above the neutral a xis of the T-bea m).

The best way to predict the required heat input of the

straightening process is to create an empirical tablewith data derived from full-scale experiments. Thefinal condition of the beam is usually obtained afterapproximately 1 hour after welding was finished.Theoretical calculations require a lot more dat a. H eatdistribution in a beam can be measured and then beused as part o f these calculations. The heat distributionin a T-bea m (same size as used in ab ove ca lculat ions) isshown in figure 14.

A b eam is free from distortion (camber) when the heatinput from the welding process can exactly be ba lanced

by the heat input from t he induction heater:

heat input abo ve Neutral Axis = heat input belowNeutral Axis

or expressed by formula:

(4) w X b x (xweldtemp) dx = H X a x (xheating) dx(Temperature x length to neutra l axis)

WhereX b = distance to neutral axis (welding).

(xweldtemp) = heat d istribution in the T-beam fro mwelding pro cess.

X a = distance to neutral axis (heating).(xheating) = heat distribution in the T-beam from

heat ing process.

By solving the integrals in formula and by using theheat distribution as shown in the figure the heat inputon both sides of the neutral axis must be equal.

6 Reference s

1996, A ndersen N.H igh deposition welding with sub-arc forgotten a nd

overloo ked po tentia l, Svetsaren Vol. 51, No.3, p. 12 19.

1987 Conner L. P.Welding Technology, Welding H and boo k, E ighth

Edition, Vol. 1, American Welding Society, p. 241 264.

1989, ESABKrympning, D eforma tioner, Spnd inger.E SAB s handbgsbibilitek 9 (in da nish).

1991, G ustavsson J .Automa tic production machinery for the fa brication

of welded steel beams and profiles. Svetsaren Vol. 45No.2, p. 46-30.

1977 Ma lisius R .Schrumpfungen, Spannungen und Risse beimSchweissen 4. A uflage, 154 p, D VS Verlag,ISB N 3-87155-785-4.

1996, P ersson M .Manufacture of welded beams. Svetsaren Vol. 51,No.3, p. 20-21.


Figure 14. Heat distribution in a T-beam during the welding

operation.

About The Author:

Herbert Kaufmann, M. E l. Sc. and M. Mech. Sc., joi-ned E SAB in 1988 as Technical D irector at E SA BAutomation Inc., USA. He is currently working asProject Manager within the EngineeringDepartment of ESAB Welding Equipment in Lax

Sweden.


16/44


Translation of an article first published in Laswijzer,

the customer magazine of ESAB The Netherlands.

By: Guus Schornagel, ESAB, The Netherlands.

Improved welding efficiency has been a major consideration for Dutch boatbuilder, Royal

Huisman, in the planning, design and construction of The Athena the worlds largest

aluminium yacht. T his has been achieved by implementing mechanised M IG welding with

Railtrack FW 1000 for horizontal and vertical butt welds on the yachts hull.

ESAB Railtrack FW 1000 aids

fa brica tion effic iency o f the

worlds largest aluminium yacht

If you can d ream it, we can build it.

The making of a sailing yacht is an intense

synergy between art and science,

between heart and hand : It is a striking

harmony between rough sketches onfoolscap and c risp printouts on mylar; a

translation of vague mental conception

into hard-edged lofting; a focusing of dif-

fuse artisy into plasma-sharp cutting; the

landing of eupho ric flights of imagination

by a micro chip' s swift calculation.

(Excerpted from "Juliet: The Creation o f a

Masterp iece" text by Jack A. Somer and

photographs by Peter Neumann).

Royal Huisman

The history of this D utch yard da tes ba ck to 1884 whenthe Huisman family started to build many differenttypes of wo oden boa t. From 1954, all boa ts were fa bri-cated in steel and, in 1964, the ya rd w as am ong the f irstin Europe to construct boa ts in aluminium. In t he fol-lowing years, Huisman expanded this specialisation tothe point where, today, all their products are madefrom aluminium. The compa nys in-house mot to is" if you can dream it, we can build it."

The yard employs some 325 personnel, including thoseof R ondal, a supplier of masts, deck fittings and winch-

es. Huisman personnel work directly for the customerwhich results in a high degree of flexibility and effi-ciency during the build process. The yard has its ownadvanced composites department, painting halls, and

an advanced furniture workshop that produces inter-nal designs to sat isfy the wishes of individual clients.Huisman is renowned for its global customer base.The legendary Flyer I and Flyer II, winners of theWhitbread Race around The World, with captainCo nnie van R ietschoten, are perhaps the most fa mousexamples of Huismans performance.

The AthenaOn November 22 in 1999, after a year of intensive prepa-ration and design, the contract was signed for the con-struction of the worlds largest three-master schooner -The Athena. With a to ta l length of a lmost 90 meters, she

is the largest yacht ever to be constructed in aluminium.The Athena project came to life on the drawing boa rd ofdesigners Pieter B eeldsnijder and G erard D ijkstra a ndwill be completed in September 2004.


17/44


About the author

Guus Schornagel joined ES AB in 1966, and until hisretirement in 2001 he had various technical-commer-cial positions, among others as PR manager forESAB The Netherlands. Currently, he works as afreelance technical writer fo r La swijzer, the customermagazine of E SAB The Netherlands.

Significant features of the vessel are: tota l length: 90m width: 12.20m depth: 5.5m three 60m masts two 2000 HP Caterpillar engines weight : 982 ton total sails surface: 2474 m2

crew: 21 persons

The hull, produced in Huismans indoor hall, took oneyear to construct. Hulls are usually constructed up-sidedown. However, the unusual dimensions of The Athenamade it necessary to build in the upright position.

The welding

The construction of a ship hull requires an enormousamount o f welding. Trad itionally, manual MIG weldingwa s applied for horizonta l and vertical butt joints in the

hull. However, the scale of this project made higherwelding efficiencies and econo mies very important.

In close cooperation with ESABs product specialist,Piet Lankhuyzen, the possibilities of using ESABR ailtrac equipment were investigated.Demonstrations and tests were carried out at the yardand further production advice was offered by a notheryard, B arkmeyer in Stroobos, that had several years ofsatisfactory experience with Railtrack equipment.Royal Huisman finally opted for ESABs Railtrac FW1000 Flexi Weaver with a 30 meter long rail and vacu-

um suction brackets. The thickness of the hull platesvaries between 10 and 15mm and the equipment isused for both horizontal as well as vertical joints. Thewelds are primarily built-up in three layers, one rootpass and tw o cap beads.

P rod uction experience

Huismans production manager, Henk Petter, is verysatisfied with the results so far. He cites " reduced arctime, the consistent w eld qua lity, the absence of lack offusion defects, and, very importantly, the fa ct tha t t hework ha s become less strenuous for the welders" as themost appealing improvements.

" The welders have been involved right from the start" ,says Henk, " which facilitated t he implementation a ndaccepta nce of t he new technology. The close co-opera -tion between the yard and ESAB has played a crucialrole in t his process."

Ra iltrac FW 1000

Suited for welding magnetic and non-magneticmaterials in all positions.

Quick fit-up and user friendly. 5 programmable settings. Ca librated settings in cm, mm and seconds. Programmable function for crater fill-up.

Instructive handbook for programming. Flexible rail without rack mad e of stand ard a luminium

profile.

R ail can be lengthened or shortened as required. Optional unit for torch angle adjustment. Tilting weaving unit for fillet w elds (optional). Rotatable weaving unit for horizontal movements

on vertical slanting joints (optional). Ho vering head for mechanical height adjustment

(optional). Remote control for parameter setting.


18/44

The c oo ling ra te d ete rmines the properties

The mechanical properties of a welded joint signifi-cantly depend on the cooling rate of the joint, and this

in turn is influenced by the heat input (welding ener-gy), plate thickness and working temperature (inter-pass temperat ure). The most significant microstructurechanges from the viewpoint of the properties of theweld metal a nd the heat-affected zone take place dur-ing the cooling of the joint within the temperaturerange of 800-500C. It is usually the cooling time t 8/5,i.e. the time required for this temperature range to bepassed, which is used to describe the cooling rate.

It is recognized t ha t high hea t input (kJ /cm, kJ/mm),i.e. a long cooling time t 8/5 (s) weakens the mechanical

properties of the joint - both its tensile strength andimpact toughness. Toughness is generally more sensi-tive than tensile strength to high heat inputs. Forexample, heat input is high when the welding speed(travel speed) is low, as shown in the equation:

Welding current x A rc volta geWelding energy =

Welding speed(arc energy)

6 x I (A ) x U (V)E = (kJ/mm)

1000 x v (mm/min)

H ea t input = t herma l eff iciency fa ct or x w eld ingenergy (arc energy).

Q = k x E (kJ/mm)

Thermal efficiency factor (EN 1011-1): Submerged arc welding: 1 MIG /MAG and MMA welding: 0.8

Figure 1 shows schematically the effect of coo ling timeon the hardness and impact toughness of the heat-

affected zone. O ptimal properties will be obt ained forthe joint when the cooling time is within range II.

Figure 1. Effect of cooling time on the hardness and the

impact toughness of the heat-affected zone of the welded

joint .

When cooling time is short, i.e. when the weld coolsquickly (e.g. low hea t input or considerab le plate thick-ness), the hardness within the heat-affected zoneincreases greatly as does the tendency to hydrogencracking because of hardening. On the o ther hand, theimpact toughness properties are good, i.e. the transi-tion tempera ture is low. Likewise, if the coo ling time isvery long, hardness will remain low but the impacttoughness properties will be impaired, i.e. the transi-tion temperature rises to higher temperatures and ten-sile strength may decrease.

Heat input to b e restricte d

To ensure sufficient impact toughness in the weldedjoint, it is necessary to restrict the maximum heatinput. This need to restrict maximum heat input is somuch the greater, the more demanding is the particu-lar steels impact toughness (i.e. the lower the guaran-tee temperature of the impact toughness is), the high-er its strength class and the smaller its plate thickness.

When the issue is that of impa ct toughness requirementsat -40C or lower, for example when applying thick

welds in submerged arc welding applications, then theupper limit for heat input is of the o rder of 3-4 kJ/mm.


How much hea t ca n va rious s teels a nd

filler metals withstand?By J uha Lukkari, ESAB Oy, Helsinki, Finland and Olli Vhkainu, Rautaruukki Steel, Raahe, Finland

The mechanical properties of welded joints and, in particular their quality in pro-

duction welds, is amongst the most important considerations when developing

welding procedures. High heat input (welding energy), in particular, weakens the

toughness properties of welded joints.

I II III

Hardness

Trans ition

temperature

Co oling time t 8/5


19/44

High heat inputs cause powerful grain size growthwithin the overheated heat-affected zone, immediatelyadjacent to the fusion line. Moreover, this causes theformation of microstructures, within the heat-affectedzone, that are disadvantageous from the viewpoint ofductility; for example, grain-boundary ferrite, polygo-nal ferrite and side plate ferrite. Furthermore, impuri-ties (sulphur and phosphorus) segregate to the grainboundaries, which also impairs ductility. Similar char-acteristics also apply to the weld metal.

Rautaruukki is, possibly, the first, steel mill in theworld to have drawn up heat input graphs for its pro-duction steels. The graphs w ere ba sed on the results ofextensive tests in which fine-grained steels were sub-jected to different heat inputs for welding. Impacttoughness was tested b y studying different zones in thewelded joints.

The lower the heat input, the more passes have to be

made, and the lower, generally, is the deposition rate.This has the effect of diminishing the productivity ofwelding. The general aim is to use high heat inputs,

which is restricted by the heat-input limits issued bythe steel mill on a particular steel grade. Rautaruukkihas published heat input restrictions on its steels in theform of w elding energy or heat input graphs, e.g. in the

boo klet H itsaa jan opa s (Welding guide), Figure 2.

R estricting heat input can also be indicated by means ofcooling time t 8/5. Rautaruukki presents the maximumallowable cooling times for various steel grades in thebooklet, Table 1. The booklet also sets out the instruc-

tions for determining cooling times, which can be doneby calculation, or graphically by means of a no mogram.

Ra utaruukki repea ts res ea rch

Since the publication of the first heat input graphs, in1972, Rautaruukki has conducted many studies into

the effects of heat input - most recently in 2001-2002.On the basis of these tests, the heat input recommen-dations for the foremost R autaruukki hot-rolled steelswill be reviewed and where necessary the instructionswill be reformulated. By applying the heat input rec-ommendations it will be possible to ensure maximumproductivity of welding joints along with the impacttoughness and tensile strength firmness requirementsimposed on joints.

The plate thicknesses used were 12mm (two-run welds,not reported in this shortened article), 20mm and

40mm. Submerged arc welding, which readily enableshigh heat inputs, was the process applied. The heatinput in the tests va ried between 20 and 80 kJ/cm.

The first group comprises conventional a nd commo nlyused steels, fine-grained steel RAEX Multisteel(corresponds to E N 10025: S355J 2G 3 and S355K2G 3)and the genera l structural steel S355J2G 3 (EN 10025):

Strength properties: R eH = min 355 N/mm2

( 16mm) a nd min 345 N/mm2 (s1640mm),R m= 490-630 N/mm2.

Impact toughness (RA E X Multisteel): min 40 J/-20C. Impa ct toughness (S355J2G 3): min 27 J /-20C .


S355J2G 3 (= Fe52D) 30 -20

S355N 30 -20

S355NL 20 -40

S420N 25 -20

S420NL 15 -40

S355M 40 -20

S355M L 30 -50

S420M 35 -20

S420M L 25 -50

S460M 35 -20

S460M L 25 -50

S500M 35 -20

S500M L 25 -50

Steel grade t8/5 T

EN 1) 2)

(s) (C)

Table 1. Maximum values for cooling timet 8/5 as issued forRautaruukki steels.

6.0

5.6

5,2

4.8

4.4

4.0

3.6

3.2

2.8

2.4

2.0

1.6

1.2

0.8

Heat Input (kJ/mm) EN 10025

S355N

S355J2G 3

EN 10113-2

S420N

S355NL

S420NL

Figure 2. Heat input limits for Rautaruukki steels when weld-

ing butt joints.

10 20 30 40 50 60

Plate thickness (mm)

1) Co oling time t8/5.2) Testing temperature fo r impact toughness.


20/44

The second group comprised thermo-mechanicallyrolled (TM) steels, whose ability to withstand highheat inputs is, as is well known, good:

R AE X 420 M/ML (E N 10113-3: S420M/ML ): Strength properties:R eH = min 420 N/mm2 ( 16mm) a nd min 400 N/mm2

(s>1640 mm), R m= 500-660 N/mm2. Impa ct resista nce (M): min 40 J /-20C. Impa ct resista nce (ML): min 27 J /-50C .

R AE X 460 M/ML (E N 10113-3: S460 M/ML ): Strength properties: R eH = min 460 N/mm2

( 16mm) a nd min 440 N/mm2 (s>1640 mm),R m = 530-720 N/mm2.

Impa ct toughness (M): min 40 J/-20C . Impa ct toughness (ML): min 27 J /-50C .

New markings: RA EX 420 ML= RA EX 420 MLOP TIM (E N 10113-3: S420 ML ).

New markings: RAEX 460 ML = RAE X 460 MLOP TIM (E N 10113-3: S460 ML ).

The filler metals were the ESAB wire-flux combina-tions ty pically used with these steels, Tab le 2.

The w ire-flux combinat ion used w ith fine-grained steelRAEX Multisteel and the general structural steelS355J2G 3 was the non-alloyed O K A utrod 12.22 +OK Flux 10.71 and for TM steels it was the nickel-alloyed OK Autrod 13.27 with flux OK Flux 10.62.

This combination produces good impact toughness inmulti-run w elding dow n to 60C.

Test plates were tested to determine their tensilestrength b y means of a transverse tensile test a nd theirimpact toughness was examined along different zonesin the joint (weld metal, fusion line and heat-affectedzone: fusion line + 1 mm and fusion line + 5 mm).

The impact test results a re present ed in Tab les 3-6, andthese results are dealt with in the following.

The results were goo d, some even surprisingly excellent.What else can one say when the entire joint withstandsa hea t input of 80 kJ/cm and when the impact energypersists a t 100-200 J at test t emperature of 50C!

Impa ct toughnes s of 40mm joint

The results for 40 mm TM steel plates were extremelygood and they easily met the requirements of Tables 3and 4. The applied hea t inputs were extremely high, 70kJ /cm a nd 80 kJ/cm. S420 M/ML and S460 M/ML wereable to easily withstand heat inputs as high as theseand the impact energy of the heat-affected zone

exceeds 100 J a t the test temperature of 50C. E venthe weld metal would appear to be able to withstandthis. In the case of steel S460 the value of the impactenergy of the weld meta l also exceeded 100 J a t 50C .

Also, steels R AE X Multisteel and S355J2G 3 and theirweld metals were surprisingly able to withstand heatinputs as high as 70 kJ/cm when impa ct resista nce wa stested at 20 C, Tab les 5 and 6. H owever, the safe limitis most probably much lower than this.

It should be bo rne in mind tha t t he impact toughnessof the weld metal is also significantly affected by theweld structure (run sequence) and the reheating of fol-lowing runs, which may be manifested in the tables forwelds involving 45-, half-V, and 60-V grooves. In thecase of a weld having a different run sequence, theimpact energy value could be different, e.g. it could belower, even if the heat input were the same.

Impact toughness of a 20 mm joint

The hea t input in welding TM steels wa s 55 kJ /cm.Steels and weld metals withstood such high heat inputsextremely well. Impact toughness was tested, at therequired test temperatures, down to 50 C, Table 3and 4.

When welding the steels RAEX Multisteel andS355J2G 3 the heat input varied betw een 30 kJ/cm and55 kJ/cm. The coo ling times become co nsidera blylonger than when welding 40 mm plates even thoughthe heat input is considerably lower. The maximumheat inputs appear to be excessive from the point of

view of the weld metal, and the upper limit is perhapsaro und 45 kJ/cm with t he impact t est tempera turebeing 20C, Tables 5 and 6.The same rema rks concerning the run sequence a pplyin this case for impact properties of the weld metal asare mentioned for 40 mm plate.

Heat input and pla te thickness

Heat input, alone, may be misleading. Heat inputshould always be considered together with plate thick-ness. These, together with the interpass temperature,specify the cooling rate of the weld.

The tables reveal, for example, that a heat input of 80kJ /cm with plate thickness of 40 mm gives a coo lingtime t8/5 of 59 s. With pla te thickness of 12mm, the coo l-

O K Autrod 12.22 S2Si -

O K Flux 10.71 - S A AB 1 67 AC H5

Wm: 12.22+10.71 S 38 4 AB S2Si -

O K Autrod 13.27 S2Ni2 -

O K Flux 10.62 - S A FB 1 55 AC H5

Wm: 13.27+10.62 S 46 6 FB S2Ni2

O K Autrod 12.34 S3M o -

O K Flux 10.62 - S A FB 1 55 AC H5

Wm: 12.34+10.62 S 50 5 FB S3M o -

Wire, flux and EN 756 EN 760

weld metal

Table 2. The filler metals used in submerged arc welding and

their EN classifications.



21/44


20 45-1/2-V 55 98 5 Wm 177 162 155

Fl 179 225 198

Fl+1 240 205 162

Fl+5 283 274 270

Parent material 299 299 270R equirement: M min 40 - -

R equirement: M L - - 27

40 60/90-X 80 59 3+3 Wm 136 73 44

Fl 207 199 185

Fl+1 243 233 242

Fl+5 299 229 119

Parent material - - 230

R equirement: M min 40 - -

R equirement: M L - - min 27

20 45-1/2-V 55 98 5 Wm 156 112 79

Fl 127 71 63

Fl+1 123 149 127

Fl+5 228 188 181

Parent 214 191 173

material



40 60/90-X 80 59 3+3 Wm 203 157 102

Fl 210 164 156Fl+1 241 207 195

Fl+5 261 258 168

Parent material - - 326



Plate Joint Heat Cooling time Number of Impact test: Impact Impact Impactthickness preparation input t8/5 passes location energy energy energy

(mm) Q (s) -20C -40C -50C

(kJ/cm) (J) (J) (J)

Table 3. The impact toughness of welded joints in S420 M /ML steel.

Submerged arc welding. Filler metals: OK Autrod 13.27+ OK Flux 10.62. P rehea ting: No . Interpass temperature: 50-80 C. Wm = weld metal, Fl = fusion line, Fl+ 1 = fusion line + 1 mm etc. Impact energy: mean of three tests.

Table 4. The impact toughness of welded joints in S460 M /ML steel.

Submerged arc welding. Filler metals: OK Autrod 13.27+ OK Flux 10.62. P rehea ting: No . Interpass temperature: 50-80C. Wm = weld metal, Fl = fusion line, Fl+ 1 = fusion line + 1 mm etc. Impact energy: mean of three tests.

Plate Joint Heat Cooling time Number of Impact test: Impact Impact Impact

thickness preparation input t8/5 passes location energy energy energy

(mm) Q (s) -20C -40C -50C

(kJ/cm) (J) (J) (J)


22/44

ing time for t he weld is the same (60 s) even though theheat input is only o ne-third o f t he a bove, i.e. 25 kJ/cm.Thick plates withstand considerably higher hea t inputsthan thin plates.

This research, leads to the conclusion that, when dealing

with multi-run welding of thick plates, surprisingly high

heat inputs can be used in submerged arc w elding appli-

cations without impact toughness properties being exces-

sively impaired.

Strength not a problemWhen transverse tensile tests were performed onwelded joints, the majority of th e test specimens brokeon the parent material side - all the results fulfilled the

requirements set on the parent mat erial (not reportedin this shortened article). Even the highest heat inputsof 70-80 kJ /cm did no t sof ten joint s to such a n extentthat this would have been essentially manifested in thetensile test results.

Summary

As a means of reducing labour costs and of improvingproductivity, maximum heat input must be appliedwhen welding. How ever, in order tha t sufficient impacttoughness properties might be obtained in the welded

joint, it is at times necessary to restrict the maximumheat input. The need for restriction is so much thegreater, the lower the temperatures at which goodimpact toughness properties are required, the greater


20 45-1/2-V 31 35 6 Wm - 110 62

Fl - 101 31

Fl+1 - 225 196

Fl+5 - 104 45

37 45 5 Wm - 129 55

Fl - 136 88

Fl+1 - 207 160

Fl+5 - 108 66

43 60 5 Wm - 84 61

Fl - 109 56

Fl+1 - 167 144

Fl+5 - 91 91

55 98 4 Wm - 100 57

Fl - 111 39

Fl+1 - 179 136

Fl+5 - 79 70

60-V 50 81 2+1 Wm 42 25 17

Fl 101 66 35Fl+1 115 78 37

Fl+5 183 134 52

Parent material: - 114 64

R equirement: - min 40 -

40 60/90-X 70 40 3+3 Wm 72 69 35

Fl 111 63 35

Fl+1 80 53 27

Fl+5 105 51 27

45-K 71 43 3+4 Wm - 40 38

Fl - 109 70

Fl+1 - 90 79

Fl+5 - 175 174


R equirement: - min 40 -



(mm) Q (s) 0C -20C -40C

(kJ/cm) (J) (J) (J)

Table 5. The impact toughness of welded joints in RAEX Multisteel.



23/44


20 45-1/2-V 31 35 6 Wm - 95 61

Fl - 112 79

Fl+1 - 178 125

Fl+5 - 43 19

37 45 5 Wm - 103 58

Fl - 120 60

Fl+1 - 132 52

Fl+5 - 51 20

43 60 5 Wm - 113 52

Fl - 80 44

Fl+1 - 90 58

Fl+5 - 74 45

55 98 4 Wm - 73 31

Fl - 57 32

Fl+1 - 112 56

Fl+5 - 50 29

60-V 50 81 2+1 Wm 48 21 13

Fl 47 31 20Fl+1 55 35 25

Fl+5 76 71 23


Requirement: - min 27 -

40 60/90-X 70 40 3+3 Wm 70 56 27

Fl 94 62 34

Fl+1 73 45 27

Fl+5 104 46 33

Parent material: - 83 -

Requirement: - min 27 -



(mm) Q (s) 0C -20C -40C

(kJ/cm) (J) (J) (J)

are the tensile strength requirements, and the thinnerthe plate being welded.The research showed tha t modern-day steels and weld-ing filler metals can withstand surprisingly high heatinputs when welding thick plates and using multi-runarc w elding.

In a light-hearted sense, one could say that the results

for t he heat-affected zones and weld metals were suchthat the traditional impact toughness competitionbetween steel manufacturer Rautaruukki and fillermanufacturer ESA B ended in a draw!

Table 6. The impact toughness o f welded joints in S355J2G3 steel.


About The Authors:

J U H A L U K K A R IIs H ead of Technical Service D epartment at E SABOy, H elsinki, Finland

OLLI VHKAINU

Is Product Manager at Rautaruukki Steel, Raahe,Finland


24/44

Acknowledgement

We thank B rasFEL S production management for theirsupport in producing this art icle.

In B razil, offshore f ields supply 80% of t he countrysoil requirements, some 60% coming from very deepwa ters, underlining the importance o f o ffshore opera-

tions for the Brazilian economy. As a consequence,there is a very high level of offshore activity.B rasFEL S has recently built two FPSO vessels for theCa ratinga and B arracuda o il fields (Figure 1), and hasanother tw o FP SO vessels in its order book.

OK Tubrod 75

The Caratinga FPSO was completed earlier this year.Two consumables were widely a pplied, O K Tubrod 71U ltra (E 71T-1) for FC AW of co mponents fo r a servicetemperature down to 30 C and the b asic OK 55.00(E 7018-1) stick electrode fo r the welding of E H 36 with

a C VN impact requirement down to 40 C.For the construction of the Baracuda FPSO, a higher

welding productivity w as required and the yard evaluated

other consumables and processes. Replacement ofMMA with OK 55.00 by FCAW was considered aviable option for increased productivity, provided thatthe new consumable yielded a t least t he same mechan-ical properties. OK Tubrod 75, a development ofE SAB s Bra zilian cored wire factory, was evaluated byBrasFELS and was judged to be the best available.

OK Tubrod 75 is an all-position basic cored wire (E71T-5/E71T-5M) for use in b oth C O 2 and Ar/CO 2 shieldinggas. For reasons of availability and optimum outdoor

gas shielding, the BrasFELS yard prefers the use ofCO 2. Table 1 surveys the chemical composition andmechanical properties of OK Tubrod 75 in the as-weld-ed condition. Table 2 gives an overview of the satisfac-tory results of tensile, bend, impact and hardness testsderived from the Welding Procedure Specifications inEH 36. ESAB B razil assisted the B rasFELS ya rd in theestablishment of these procedures and obtained thenecessary AB S approval (4SA, 4Y SA H 10).

Tab le 3 and 4 give the Welding P rocedure Specificationsin 2G and 3G positions for a 60 V-joint with a nominal

roo t opening of 8mm and a land of 1mm, in 25mm platethickness. Root passes are welded on ceramic backingstrips.


ESAB Brazil provides BrasFELS

shipyard with extra FCAW productivity

for offshore vesselsBy: Jos Roberto Domingues, Technical Manager Consumables and Cleber J.F.O Fortes, Technical Assistant, ESAB Brazil.

The BrasFELS shipyard, in Angra dos Reis, Brazil is involved in the conversion of

petroleum tankers to FPSO (Flotation-Production-Storage-O peration) vessels.

O K Tubrod 75 all-position basic cored wire, a Brazilian development with European,

US and K orean equivalents, passed the yards extensive qualification tests to provide

extra FC AW productivity.

Figure 2 . Conversion to FPSO vessel.

Figure 1. Barracuda & Caratinga Project.


25/44

ProductivityThe conversion from MMA to FCAW yielded similarbenefits in productivity as those previously achieved byB rasFEL S when they introduced O K Tubrod 71 U ltra.The comparative performance of table 5 is based on astandard cost calculation applied by the yard. Theresulting improvement in relat ive welding costs is near-ly 35% which is a welcome reduction for a ny shipyard.

Note: O K Tubrod 75 is a local product fo r the B razilianmarket. Basic ESAB types for offshore fabricationwith a compara ble performance are:

OK Tubrod 15.24 and FIL AR C PZ 6125 for E urope.D ual Shield T5 for the U S and A sia P acific.


About the authors

J os Ro berto D omingues is Technical Ma nagerConsumables for ESAB Brazil. He is responsible for theR &D and q uality control of welding consumables andtheir applications. H e joined E SAB in 1988.

Cleber J.F.O. Fortes is Technical Assistant in the field ofarc welding consumables. He has been involved in wel-ding for over 20 years, and joined E SAB in 2001.

Typical chemical composition of the weld metal (% )

C Si M n

C O 2 0.040 0.50 1.50

Ar+CO 2 0.055 0.53 1.68

Typical mechanical properties of the weld metal

Strength Y ield Elong. Impact

(M Pa) (M Pa) (% ) (J) at -40C

C O 2

(DC -) 480 400 22 90

Ar+CO 2

(DC +) 480 400 22 40

Dep. Net dep. Rela tive

ra te ra te cos t

(mm) (kg/h) (kg/h) (%)

OK 55.00 4.0 1.75 0.52 100

OK Tubrod 75 1.2 2.78 1.11 65.5

Table 1. Typical properties of OK Tubrod 75.

Table 5. Welding costs.

Welding P roces s: FCAW Position: 2G

Ba se Material: EH 36 Thicknes s: 25.4 mm

Filler Meta l: O K Tubrod 75 1.2 mm

Classification: AWS A 5.20 E71T-5 (M )

Shielding Gas: C O 2 / 18 L/min

Preheat: 21C min. Interpass: 250C max.

Tec hniq ue: M aximum weave 25.0 mm

Electrode extension: 10 - 15 mmCurrent / P olarity: DC -

Weld Current Volta ge Tra vel Hea t

La yer S peed Input

(A) (V) (mm/s ) (kJ /mm)

Root 140 24 1.1 3.1

2nd Pass 130 24 3.5 0.9

Fill 160 25 4.7 0.9

C ap 175 25 4.7 0.9

Welding P roc es s: FCAW Position: 3G

Base Material: EH 36 Thicknes s : 25.4 mm

Filler Meta l: O K Tubrod 75 1.2 mm

Classification: AWS A 5.20 E71T-5 (M )

Shielding G as : C O 2 / 18 L/min

Preheat: 21C min. Interpass: 250C max.

Tec hnique : M aximum weave 25.0 mm

Electrode extension: 10 - 15 mm

Current /Polarity: DC

Weld Current Volta ge Tra vel Hea t

La yer S peed Input

(A) (V) (mm/s) (kJ /mm)Root 150 23 0.6 5.8

2nd P a s s 130 22 1.3 2.2

Fill 130 22 3.0 1.0

Ca p 130 22 3.3 0.9

Table 3. Welding procedure data, 2G position.

Table 4. Welding procedure data, 3G position.

60

25.4mm

8.0mm1.0mm

Figure 3. Bevel configuration.

Tens ile tes ts

2G 550 M Pa, ductile fracture in base metal

580 M Pa, ductile fracture in base metal

3G 530 M Pa, ductile fracture in base metal

540 M Pa, ductile fracture in base metal

Side bend tests: no cracks

Impac t tes ts (J) at -40C

Weld centre Fusion line Fusion line Fusion line

+2 mm +5 mm

2G 36 / 44 / 48 126 / 44 / 44 30 / 40 / 30 70 / 72 / 34

av. 42.7 av. 71.3 av. 33.3 av. 58.7

3G 36 / 28 / 28 22 / 58 / 76 40 / 32 / 66 90 / 56 / 52

av. 30.7 av. 52.0 av. 46.0 av. 66.0

Hardness tests (HV5)Base metal Weld metal Heat affected zone

2G 157 - 185 201 - 236 185 - 286

3G 160 - 177 189 - 244 191 - 248

Table 2. Destructive tests.

OK TUBROD 75

COMPARATIVE PERFORMANCE

WELDING PROCEDURE, 2G POSITION

WELDING PROCEDURE, 3G POSITION

DESTRUCTIVE TESTS


26/44

Secure fillet weld penetration with downhillMAG welding

Ongoing development of the OK Tubrod 14.12 metal-cored wire has resulted in a consumable with a verysecure penetration that avoids the above mentionedwelding defects associated with dow nhill MAG weld-

ing. The weld penetration depth has been recordedbetween 1.3 and 2.0mm when using CO 2 shielding ga sand between 1.0 and 1.5mm for M21 mixed gas. Thesedepths are comparable to the very secure penetration


Secure downhill MAG welding

of butt- a nd fillet w elds w ith

ES AB OK Tubrod 14.12Translation of an article first published in Fenster,

the ESAB G ermany customer magazine.

By: Dipl. Ing. Frank Tessin, ESAB GmbH, Solingen, Germany.

The downhill welding of fillet welds by the M AG process is regarded as an insecure

method by many in the welding industry, and is, therefore, rarely used. Some G erman

shipyards, however, have successfully developed and applied downhill welding proce-dures for thin-walled applications using O K Tubrod 14.12 metal-cored wire.

Root defects

Welding defects in the root of the weld, a ssociated w ithdownhill MA G welding, have made shipbuilders reluc-tant to apply this method, in spite of the productivitybenefits offered by the process. Typical root defects are:

Lack of penetrat ion. The occurrence of slag or slag particles in the back

of the root when using flux-cored wires. Lack of fusion when using solid wire.


27/44

observed in uphill welding with rut ile flux-cored w ires.OK Tubrod 14.12 is normally welded with polarityand welding parameters are carefully adjusted toobtain optimum weld penetration. With a single bead,fillet welds with a t hickness of a= 2.5 to 3.5mm are per-

fectly fea sible. Thicker fillet w elds must be uphill weld-ed with rutile flux-cored wire or downhill depositingmulti-beads with OK Tubrod 14.12.

It is essential to avoid pushing-up the arc, in order toobt ain a la rge fillet weld thickness. In this case, the arcwill burn onto a large weld pool which will go at theexpense of the good weld penetration.

Additional benefits

Add itional benefits of the downhill MAG welding offillet welds w ith O K Tubrod 14.12 are:

A concave weld cross section without undercut. A smooth fine-rippled weld surface. A low heat input (4-5 KJ /cm). Minimal distort ion. A high welding speed (50-70 cm/min.).

A new fab rica tion metho d for butt w elds

Exploring the possibilities of this high penetration

welding consumable, german shipyard H D W Kiel,

tested the vertical down welding of butt welds. The

results were remarkably positive and led to a com-pletely new production technique by which I-joints, in

plate thickness 3 to 7mm, and V-joints, in plate thick-

ness >8mm, are welded extremely fast and without


Figure 7. Weld pool of

the roo t layer.

Root

Figures 4 to 6. building-up o f runs, square butt weld, t = 7 mm; vertical down welding.

2mm gap 3mm gap

4mm gap 5mm gap

Figure 8. I-butt, t = 6 mm. Gap bridging possibility of the

OK Tubrod 14.12 at gap variation.

Figure 2a. Penetration, vertical

down welding with solid wire.

Figure 2b . Penetration, vertical

down welding with metalpowder w ire XX (pos. pole).

Figure 3. safe penetration

in vertical down weldingwith OK Tubrod 14.12.

Root w ith final run on either sideRoot with 1stfinal run


28/44

ceramic ba cking material. The I-joints are given a larg-

er than normal root gap, and during welding a phe-

nomenon occurs that has not b een observed before in

welding. Under the influence of the arc and the very

hot weld pool, the plate edges are securely melted

without a ny fusion faults, while the ro ot is contracted

along the centerline of the joint.

The root is exactly located in the neutral zone of theplates, resulting in a total absence of angular distortiondue to shrinkage a problem that is almost alwayspresent when welding thin plates and req uires cumber-some straightening work.

A further benefit of this type of root is that it ha s a verysmooth t ie-in, avoiding fusion faults when welding sub-sequent layers.This technique is a pplicable f or pla te t hicknesses from5-7mm. For thinner plates, the common two layertechnique is being used, with a smaller root gap. With

plate thickness above 8mm, there is a risk of fusiondefects. Because of the high welding speed, the heatinput is no longer sufficiently high to melt the weldedges thoroughly. This can be solved easily, however,by changing the joint to a V-design where the plateedges require less energy to be melted. From the ya rdsresearch it w as concluded t hat the dow nhill welding ofV-joints is possible up to plate thickness of 12-15mm.For t he welding of I -joints up to 7mm thick, a few mil-limeters root ga p tolerance is acceptable w ithout lead-ing to a ny prob lems (figure 8).

Metallurgically perfectThe welded joints are easily tested by X-Ray. Fusionfaults intro duced by la ck of skill give clear indica tions.The excellent mechanical properties have been con-firmed by various tensile, bend and CVN impact tests.Weld metal and H AZ hardness increase has not b eenobserved.

A higher productivity and increased flexibility

Productivity calculations yield a welding time that isreduced by 80% for 4mm thick plate, compared with

solid wire MAG welding. The savings on straighteningwork are even substantially higher. Even for 8mmplate, compa red w ith rutile flux-cored w ire, savings areachieved, a part fro m reduced straightening work.Ano ther aspect to b e considered in relat ion to V-jointsis the flexibility. Should fit-up wo rk result in to o la rgea roo t gap, one can a lways revert to uphill welding withrutile wire and ceramic backing. Ro ot gaps that are toosmall can be covered downhill with OK Tubrod 14.12metal-cored wire. Corrective work during fit-up of thejoints is, therefore, never needed.


About the author

Frank Tessin, M.Sc, is Product Mana ger Cored Wiresat E SAB in Germany.He studied mechanical engineering and started w or-king for ESAB in 1992.Since two years, he is also Key Account Mana ger forES AB 's automotive business in G ermany.

Co nclusions a nd o utlook

H D W has obtained approval from G ermanischenLloyd, Lloyds Register, and BWB for the welding offillet welds and but t joints for shipbuilding steel gradesA up to D 36. The process has been used now fo r a cou-ple of years and has resulted in clear savings andincreasing weld quality. The fillet welds are slightly

concave without undercut, and the weld surface issmooth with a fine ripple. The butt welds are narrowand show o nly a sma ll over-thickness.The vertical down welding of fillet welds with OKTubrod 14.12 is relatively ea sy to learn and investmentin new welding equipment is not needed. Welders willsoon produce good quality welds, while applying thefast t ravel speeds involved. This is not eq ually valid forthe vertical down welding of butt welds, however. Ittakes time for welders to develop the skill and to pro-duce consistently high quality welds.Vertical do wn w elding with O K Tubrod 14.12 is nowa-

days the most economic solution for joining thin-walled plates. At the yards involved, it has becomecommon practice to place constructions in the verticalposition to benefit as much as possible from the eco-nomic advanta ges.The new method w ill undoubt edly change the future ofthin plate welding, in general. Further progress may beexpected from consumable development and dedicat-ed use of industrial shielding gas mixtures.


29/44

At first glance, the bevelling of plate edges may look

easy, but it requires considerable knowledge and expert-

ise to build an installation that cuts accurately and fast

and that is, at the same time, user-friendly. Over more

than 70 years, ESAB Cutt ing Systems has used its glob-

al experience in cutting installations to further improveeach generation of control units. The result is continu-

ing improvements and simpification in programming

and the use of cutting installations. This constant inno-

vation, results in lower bevelling costs, higher produc-

tivity, and increased customer competitiveness.

Bevel shapes

The welding of medium and large thickness plates

requires a w eld joint preparat ion which can be either a

V-,Y-,K- or X- bevel, depending on the welding

process, application and plate thickness.

When welding, the accuracy of the angle and the cut

quality are very important, but the straightness of the

cut is critical. If it is not perfectly straight, the root gap

will vary a nd unacceptable weld d efects are more like-

ly to occur; this apart from the fact that the joint vol-

ume increases and more filler material is needed.

This is precisely the reason w hy E SAB has caref ully

designed high accuracy height control devices and

incorporated them into all its bevelling tools. These

devices are independent fro m the cutting process itself,which varies with the cutting needs of fa bricators.

Anot her important a spect for consideration is the cut-

ting length. It is larger t han t he plate thickness and cor-

responds to t he plate thickness/C O S a ngle.


Therma l B evelling Techniq ues

By: Arnaud Paque, ESAB Cutting Systems, Karben, Germany.

The article discusses the thermal bevelling techniques available fromESAB highlighting several cutting processes and a variety of plate edge

preparation applications.

H2

L2H2

H1

H1

If Angel = 45

esab ship building by svetsaren 2003

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