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No. 4 • 2007

WELDING NEWS

Industry segmentsPart 2: Marine chemical tankers 3

Pickling smutPart 2: How to prevent smut 5

High productivity welding o thenew duplex steel, LDX 2101® 7

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No. 4 • 2007WELDING NEWS

Welding week in Antwerpen

New technicalmanager atAvesta Welding

With responsibility for ux cored

wires, solid wires and technical custo-mer support, Lars-Erik Stridh has been appointed technical manager atAvesta Welding. He succeeds MartinLarén, who has taken up a projectpost as the technical director at BöhlerThyssen Welding’s new factory inSuzhou, China.

Lars-Erik’s basic academic back -ground is in nance. This wascomplemented by further studies atSweden’s college of mining and me-tallurgy. Lars-Erik also has extensivepractical experience in welding. Onleaving formal education, he becamethe welding supervisor at a repairand maintenance company beforemoving to Elga and 13 years as theproduct manager for ux cored wires.

In 1999, Lars-Erik moved to ESABwhere he headed up the organisa-tions behind the company’s globaltechnical support, process develop-ment, process centre and laser hybridwelding.

“Starting work at Avesta Welding isa little like coming home,” says Lars-

Erik. “I was born in the Bergslagenregion of Sweden and my wife comesfrom Norberg, just outside Avesta. Iam looking forward both to new chal-lenges and also to working with allof you.”

Lars-Erik Stridh

From the 11th to the 14th of Novem-

ber, Avesta Welding was at the FAB-TECH International & AWS WeldingShow at McCormick Place, Chicago,USA. Bringing together 25,000 visitorsand over 1,000 exhibitors, the show isNorth America’s largest for the wel-ding industry.

Along with Böhler Welding Group,Avesta Welding took part inAntwerp’s “Welding Week”, 16 – 19October 2007. Welding Week is themeeting place for welding andcutting enterprises in the Beneluxcountries. It presents the latest pro-ducts and technologies in both indu-stries. Avesta Welding exhibited itswide product ranges and also took the opportunity to market its duplexprogramme. The spotlight was on thematching ller metals for welding

Outokumpu LDX 2101, which is itself being marketed as the new steel forstorage tanks.

Eric Leroux and Julien Jakubyszin, AvestaWelding France, speaking with some of thevisitors

Welding week in Antwerpen

This year’s FABTECH International & AWS Welding Show was in Chicago, USA.

Editorial teamEva Söderberg, tel: +46 226 815 05, E-mail: [email protected] Rosén

www.avestawelding.com

LayoutCentrum Tryck, Avesta

Cover pictureCarrying marble slurry for the pulp and paper industry, M/T Xanthia meetsrough seas. The ship´s cargo tanks, made in Outokumpu 2205 and integrated withthe hull, meet the challenge!

TranslationsTranstext2002

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Using duplex stainless steelsin marine chemical tankers in-creases the range o cargoesthat the vessels can carry. Outo-kumpu in Degerors has longexperience o manuacturingpreabricated chemical tankersin duplex 2205.

Although sea transport is far slowerthan air, it is an efcient means of moving large quantities of “non-perishable” goods. Over six billion

tonnes are transported across theworld’s seas every year. Ships areused for transporting a large numberof loose raw materials. These includeeverything from chemicals and petro-leum products to bulk cargoes of coal,iron ore, bauxite, etc.

Nowadays, cargo vessels are madealmost exclusively of welded steel.The modern ship industry makesfull use of prefabricated sections– complete “multi-deck” segmentsof the hull or superstructure thatare put together at one point in theshipyard and then transported to thedock or slipway, where they are liftedinto place. Additionally, the mostup-to-date yards also pre-install in-struments, pipe systems, cabling andother components in each “block”.The idea is to minimise assembly andinstallation work after the hull has been welded together.

Tankers are cargo vessels that carryall sorts of liquids; not only crude oil,petroleum products, liquid gases andchemicals, but also vegetable oils,

wine and other foodstuffs. The tankersector accounts for a third of the totaltonnage transported by ships world-wide.

A chemical tanker is purpose-designed for transporting chemicals,

2. Marine chemical tankersoften aggressive acids. Most newchemical tankers are built in yards in Japan, South Korea and China. Tur-key, Italy, Germany and Poland areamongst the other active countries.Three large owners – the NorwegianStolt-Nielsen, Odfjell and JO Tankers– presently dominate the market forchemical tankers. The end users of the ships are the large oil and specialchemical companies.

Outokumpu prefabricatesHans Gunnarsson is the business de-

velopment manager for marine che-mical tankers at Outokumpu Hot Rol-led Plate in Degerfors. The companyhas long experience in prefabricatedchemical tankers.“Our customers are shipyards, predo-minantly in China and Turkey. We arenow world-leading manufacturers of prefabricated chemical tankers in thespecial stainless steel, duplex 2205.

However, in Japan, for example, che-mical tankers are also made in carbonsteel with a plastic coating. They arecurrently our greatest competitors,”he explains.

Outokumpu works from custo-mer drawings that, for productionand the various operations involved(cutting, bending, edge preparation,welding, etc.), are adapted to thecompany’s own standards. Each shipuses between 300 and 1,200 tonnes of stainless steel. The quantity dependspartly on the ship’s destination and

whether it is for coastal, sea or oceanuse. Ocean-going chemical carriersare generally between 5,000 and45,000 tonnes deadweight. For coastalcarriers, the upper gure is 12,000tonnes. Both classes are far smallerthan average sized carriers. This is because of the special nature of che-mical cargoes and the size restrictionson the loading and unloading terminals.

This is the next instalment in the series of articles presenting some of Avesta Welding’s key segments – the pulp and paper industry (issue 2 of 2007), marine chemical tankers and desalination plants.

1 Pulp and paper 2 Marine chemical tankers 3 Desalination

Being built at the Pesaro shipyard in Italy, section of M/T Diego Cali, 6,000 dwt

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Marinechemical tan-kers normallyhave a number of se-parate storage tanks. Theseare either made in stainlesssteel or have a special surface layer

of zinc or phenyl epoxy. The materialsand coatings determine which typesof cargoes the tankers can carry.Aggressive cargoes such as sulphuricacid and phosphoric acid requiretanks in duplex stainless steel 2205.“Simpler” cargoes, e.g. vegetableoils, can be carried in epoxy-coatedtanks.

Greater exibility with duplex 2205Flexibility in the types of productsthat can be transported is a major

factor when selecting the basic mate-

rials to be used in tanks aboard sea-going vessels. If, unusually, a ship is built solely to transport one type of product, the choice is determined bythe cargo. Normally, bearing in mindfactors such as formability, weldabi-lity and strength, the cheapest ma-terial or coating is chosen. If, on theother hand, chemical tankers are tocarry various types of cargo, a mate-

rialwith

good corrosionresistance in many types of media (both alkaline and acid) is re-quired. Duplex stainless steel 2205 is just such a material.

“We’re investing in 2205. Above allelse, duplex steel has the advantageof greater strength. This results inlower ship weights. With 2205, thick -nesses can be less than with coated

carbon steel. Thus, less material isrequired and the tanker itself weighsless. In turn, this means that the shipcan carry heavier cargoes,” com-

ments Hans Gunnarsson.“Our ability to prefabricate so

much of each tanker makes usunique on the market. In countriessuch as China and Japan, this typeof prefabrication is not done. It isexactly this, in combination with

our long experience, that leads to uswinning orders from new customers.On delivery, everything is ready for

welding. We do all the forming, edgepreparation and cutting. The custo-mer receives a packet in which wehave marked the elements that are to be welded together. It’s a little like alarge LEGO,” he states.

In many cases, contracts stipulatetraining in the handling of stainlesssteel. Hans Gunnarsson indicates thatthis is another important competitiveedge for the company.

Chemical tankers are often built inseries. Outokumpu in Degerfors has,for example, received a large order

for ships that will go to an Italianshipping line. Two ships of 13,600tonnes deadweight each are to be built at a shipyard in Rushan, China.This involves a total of 2,400 tonnesof duplex 2205. The order also inclu-des an option for several tankers inthe future.

Production in Degerfors runs ataround 5,000 tonnes per year. How-ever, Hans Gunnarsson points outthat the number of orders variesgreatly.

“At the moment, we have quite alot on order and the future also looksgood. What we nd a little worryingis the price of alloying elements. Theprice of coated carbon steel is roughlyhalf that of 2205 and materials are anextremely large part of a ship’s costs.However, the advantages of duplexsteels and our unique prefabricationgive us a strong market position,” heconcludes.

Avesta Welding has very long experience in supplying stainless steel fl-

ler metals or welding storage tanks in marine chemical tankers. Besidesknowing how the tanks are best and most economically welded, we

also oer a complete package o purpose-specifc welding consumables,

training and support throughout each entire project.

Avesta Welding and Outokumpu Hot Rolled Plate oten work together

and are thus able to bring customers a unique pool o expertise cove-

ring both stainless steels and welding. The most common steel in marine

chemical tankers is duplex 2205.

Welding consumables used in chemical tanker projects have to be

approved. Avesta Welding’s fller metals have approvals rom well-known classifcation societies such as DNV,

Lloyd’s Register o Shipping, the Korean Register o Shipping, RINA, Germanischer Lloyd, etc.

Avesta Welding oers project-specifc training that meets the needs o both the shipyard and the shipping

company. Courses combine theory (in particular, everything about duplex steels and their weldability) with

thorough hands-on welding practice.

Cutaway of a marine chemical tanker

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Part 2. How to prevent smut

Surace contamination can in-hibit pickling and decrease theredox potential o the picklingsolution. Smut is easily ormedunder these conditions. To pre-vent this, thorough cleaning pri-or to pickling is recommended.

Shoeprint contamination

layer of picklingagent, which must be given the bestpossible operatingconditions. Pumps,air pressure, hosesand nozzles must be checked prior tospraying. The pick -

ling agent must beshaken or stirred thoroughly until itreaches a uniform consistency.

To promote visibility and evenapplication, Avesta’s GreenOne®220,BlueOne®230 and RedOne®240 areall strongly coloured (for the sake of contrast). If a transparent spray suchas 204 is to be used, an indicator can be mixed in to achieve a similar ef -fect. It is also important to use thecorrect pickling product for the steelgrade being treated.

To avoid smut, it is recommended

that the pickling solution should not be any more acidic than necessary.

particles that are not excessive). Table1 sets out the most important para-meters.

Where loose dust, ngerprints,shoeprints and tool marks are thecontaminants, acid cleaning (e.g.Avesta 401) is usually adequate. If thecontamination is more severe (e.g.oil and grease), alkaline cleaning (de-greasing) is also necessary. Avesta 430is a suitable degreasing agent in suchalkaline-acid cleaning (A-A cleaning).The water break test is a simple wayof assessing whether degreasing is

necessary.Where glue or silicone residues

are the contaminant, solvents (e.g.acetone or alcohol) must be used in athird cleaning step.

Uneven pickling when using a sprayOther factors besides contaminationcan result in smut. Before any pick -ling, it is important to check thatequipment is working properly andthat the environment is suitable. Werecommend following the advice in:AFC’s standard operating procedu-res; the Avesta Pickling Handbook;and, Avesta Guidelines for Planningand Designing a Pickling Workshop.

When spraying, the objective is tocover the entire surface with an even

Smut caused by pickling spray residues on the surface

This is especially important whenpickling low-alloy grades. The choiceof pickling product also depends onthe depth and density of the oxideto be removed. Pickling outdoors isknown to increase the risk of smut-ting. Factors such as sunlight, wind,humidity and temperature are hardto control and can have a huge effecton the nal results.

Uneven pickling when using a bathTests have proved that smut forma-tion is less likely in well-maintained baths. A number of parameters areimportant in keeping a bath “clean”(i.e. levels of impurities and foreign

Smut caused by uneven spray pickling

Standard pickling bath

(Avesta 302 mixed 1:3)

HNO3 ~160 g/l

HF ~40 g/l

Temperature 25–35°C

Agitation >15 times/h

Dissolved metals <35 g/l

The ratio of the acids in the pick -ling solution must also be considered.At its laboratory in Malmö, AFC cancarry out full bath analyses and, fromthe results, make recommendationsfor keeping parameters within ac-ceptable limits. Such analyses are freefor customers using Avesta’s pickling bath services.

Contaminated pickling bathPickling solutions and oil and greasedo not mix. Instead, these contami-nants tend to form a layer at the topof the bath. When an object is liftedthrough this layer, it can easily be-come contaminated. There is then ahuge risk of smut formation. The timethat elapses between pickling and rin-sing is critical here. To help preventsmut formation, we recommend that,while they are being lifted, objectsshould be treated with FinishOne™.

Inadequate rinsing Pickling acid residues are also a fre-quent cause of smut. This smut maysometimes not appear until days afterdrying. A good idea of the level of

Table1: Recommended parameters for astandard bath.

“Smut”– undesired discoloration/deposits

on stainless steel surfaces after pickling

“Smut”– undesired discoloration/deposits

on stainless steel surfaces after pickling

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acid residues can be obtained by com-

paring the pH levels of ingoing andoutgoing process water.

Hard to reach areas and narrowgaps can trap pickling acids. Thesecan leach out later and give rise tosmut. Hence, thorough rinsing ishighly signicant in smut prevention.Prior to high-pressure waterjet clea-ning, a pre-rinse (either in a rinsingvat or by drenching with tap water) isalways recommended. For optimumrinsing, it is best to rinse as soon aspossible after pickling, i.e. do not al-low the pickling solution to dry in.

Poor water quality

Poor quality rinse water can leadto smut in the form of water stains.These can be hard to remove. In mostcases, water-stained surfaces needto be cleaned with Avesta 401 or re-pickled.

Caused by impurities in the rinsingwater, water stains are primarilydeposits of calcium and magnesium.The total amount Ca and Mg in water(Fe and Mn are sometimes also inclu-ded) is expressed as water hardness.This is often measured in German de-grees hardness (°dH). Indicator paper

provides an easy way of measuringhardness.

Other impurities in rinse water canalso have negative effects on surfaces.For example, high chloride levels cancause pitting.

0–2 °dH Very sot

2–5 °dH Sot

5–10 °dH Normal

10–20 °dH Hard

>20 °dH Very hard

Table 3 sets out some of the mostsignicant water quality parametersand shows their typical and highestrecommended values.

Using demineralised water or Fi-nishOne™ as a nal rinse preventsthe type of smut that is attributable topoor water quality.

Nitrate-free pickling solutionsApart from problems with large

sludge volumes, nitrate-free picklingsolutions also have a shorter servicelife and are known to be particularlylikely to cause smut. Control of theredox potential is essential whenusing such solutions.

Table 3: Water quality parameters and values.

Table 2: Water hardness.

Parameter Typical values Max. recommended values

COD 2 mg/l 4 mg/l

Conductivity 38 mS/m 60 mS/m

pH 8.0 pH 6.5–9.0 pH

Hardness (Ca+Mg) 6 °dH 10 °dHChloride, (Cl) 17 mg/l 100 mg/l

Iron, (Fe) <0.01 mg/l 0.10 mg/l

Fruitful fair in China

Started in 1987 and now a force to be reckoned with, the Beijing EssenWelding & Cutting Fair has becomethe industry’s leader in Asia. At thisyear’s event (Shanghai, 19 to 22 June),we took the opportunity to makeAvesta Welding’s presence felt!

Our particular focus was on theduplex stainless steel products in thecompany’s chemical cleaning and

welding ranges. In line with this, andas an “added-value value element”for potential customers, a technicalseminar was held on how to weldmodern duplex stainless steels. Thiswas well received by invited custo-

mers and visitors alike.To better serve the fair ’s atten-

dees, we had our key brochures andleaets translated into Chinese. Wedid indeed receive a lot of enquiries,many of which invited subsequentfollow-up.

The fair was a successful collabo-ration with our two exclusive agentsin China, Eagle Plaza (North China)

and Fong’s Steel (South China). In anutshell, being part of this fair wasfruitful and worthwhile. Present andfuture customers are denitely set tosee a higher prole Avesta Welding inthe Asia Pacic Region!

Avesta Welding’s personnel and agents at the stainless steel stand

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High productivity welding of the new lean duplexstainless steel, LDX 2101® (S32101)

Many uses for duplex steelsWith their strengthening in the mid1980’s, duplex steels increasingly pro-vided an alternative to conventionalaustenitic steels. They were then pre-dominantly used for chemical tankersas well as process vessels and storagetanks in the pulp and paper industry.

It is the good combination of strength and corrosion resistancethat makes duplex stainless steels soattractive. However, in the beginning,

the duplex grades were primarilyseen as alternatives to high-perfor-mance austenitic grades (e.g. 904Land 254 SMO®) rather than as alter-natives to conventional grades (e.g.304 and 316). This limited their usein general construction. Here, highstrength is needed rather than highcorrosion resistance.

Developed by Outokumpu Stain-less, LDX 2101® , the new “lean”duplex stainless steel, is now usedin a very wide range of applications.

General purpose and structural app-

lications are just two examples. Thehigh strength and good corrosionresistance of LDX 2101® also makeit extremely suitable for a variety of storage tanks.

This article focuses on examininghow high productivity welding met-hods using Avesta LDX 2101, can be optimised to maximise the goodcorrosion resistance and mechanicalproperties of duplex LDX 2101 stain-less steel.

Strength and corrosion resistanceOf the duplex grades currently onthe market, LDX 2101® has the “leastalloyed” chemical composition (seetable 1). With a nickel content of just1.5% (balanced with 5% manganeseand some 0.22% nitrogen), LDX 2101offers high mechanical strength andcorrosion resistance at an advanta-geous price. Nickel is an expensivemetal. Furthermore, its price uctua-tes widely over time. This can presentmajor difculties when estimating the

total cost of a construction.The chemical composition of LDX2101 is balanced to give a microstruc-ture with approximately equalamounts of ferrite and austenite.Thanks to the high nitrogen content,

austenite re-formation after weldingis rapid. In general, corrosion pro-

perties are as good as, or better than,those of the Cr-Ni grade EN 1.4301/AISI 304. Furthermore, the steel’s du-plex structure and high nitrogen con-tent result in a mechanical strengthalmost twice that of ordinary, auste-nitic steels.

The high strength of LDX 2101 steelcan be used to optimise the design of various storage tanks. On top of this,the steel’s cost efciency can be fullyexploited by selecting the correct l-ler (Avesta LDX 2101) and weldingmethod.

Better properties with matching ller metalsBecause it is optimised to ensure the best welding characteristics and mecha-nical properties, the matching AvestaLDX 2101 ller should be used toweld LDX 2101® duplex stainless steel.To obtain a suitable ferrite/austenite balance in the weld metal, AvestaLDX 2101 is over-alloyed with nickel.The microstructure of metal arc wel-ded LDX 2101 has a typical duplex

appearance with 30 – 65% ferrite.Testing of LDX 2101 welds hasshown that tensile strength is higherthan 680 MPa / 99 ksi and that frac-ture most commonly occurs in theparent metal. Bending tests to 180°with a 3 x t mandrel have shown nosigns of cracking. Table 2 gives ty-

pical mechanical properties of pureweld metals.

Welding methods and weldabilityExcellent results are obtained whenwelding LDX 2101 using all conven-tional methods – MMA, FCAW, MIG,TIG and SAW. Productivity is anotherimportant factor when choosingwelding method. The current trendis towards using the most efcientmethod for each type of welding, ineach position.

General recommendations for thewelding of storage tanks are given

below.

FCAW: Widely used for all types of welding, both workshop and on-site.Suitable plate thicknesses are 5 mm(0.20”) and upwards. FCAW giveshigh productivity in all positions. Theshielding gas can be either Ar + 20% CO

or 100% CO. Welding is mainly in

the at and horizontal-vertical posi-tions. FCAW is often combined withMMA.

MIG: Especially if it can be carriedout against a backing strip, or withoverlap joints, metal inert gas wel-ding is an economical method that iswell suited to continuous welding of small thin-walled tanks (2 – 6 mm /0.08 – 0.23”). Welding is best perfor-med with synergic pulse arc transfer

Grade ASTM EN Chemical composition, typical values, %

C max N Cr Ni Mo Mn

LDX 2101 S32101 1.4162 0.03 0.22 21.5 1.5 0.3 5

2304 S32304 1.4362 0.02 0.10 23 4.8 0.3 –

2205 S32205 1.4462 0.02 0.17 22 5.7 3.1 –

304L 304L 1.4307 0.02 0.04 18.1 8.3 – –

316L 316L 1.4404 0.02 0.04 17.2 10.1 2.1 –

Table 1. Chemical composition of parent metals

Filler Mechanical properties, pure weld metals (typical values)

Avesta Rp0.2

Rm

A5

[%]Impact strenght [J]/[t-lb]

LDX 2101 [Mpa]/[ksi] [Mpa]/[ksi] RT [+20°C]/[+68°F] [-40°C/-40°F]

MMA 640/95 800/115 25 45/33 28/20

TIG 550/80 730/105 30 180/130 170/125

MIG 520/75 710/105 30 150/110 110/80

SAW 570/85 750/110 25 140/105 60/45

FCW 550/80 750/110 30 60/45 40/30

Table 2. Mechanical properties, pure weld metals

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and a shielding gas of argon with anaddition of approximately 30% he-lium and 2 – 3% CO

.

Where the thickness is 1 mm(0.039”), the SuperPulse™ mode orCMT (cold metal transfer) weldingcan be used. Compared to TIG, thesegive dramatically increased produc-tivity.

MMA: Because of its excellent exibility in all positions, MMA is emi-nently suitable for on-site vertical-upwelding, tacking and repair welding(in all positions). Avesta LDX 2101(a rutile-acid electrode) gives a stablearc, good slag removal and, in llet

welds, a concave, smooth weld rein-forcement.

SAW: This method is mostly used forwelding thick sections of sheet metals>12 mm (0.47”) and upwards. To av-oid excessive fusion of the parent me-tal, 2.4 mm (3/32”) diameter wire andV, U and X-joints are recommended.A basic ux (Avesta Flux 805) should be used for welding. The root beadcan advantageously be welded usinganother high productivity method, e.g.

FCAW. Heat input should not exceed1.5 kJ/mm (38 kJ/inch). This is be-cause, especially where the structureis used in a low temperature environ-ment, too high a degree of parent me-tal fusion can lower impact strength.

TIG: Mainly used for single-sidedroot passes and the welding of thin-walled materials, this method iscomparatively slow. However it givesvery pure weld deposits that, even atlow temperatures, have outstandingimpact properties. Productivity can

be increased by welding from bothsides simultaneously (manually orsemi-automatically).

High productivity welding methodsFor storage tanks and pressure ves-sels in process industries (e.g. pulpand paper), duplex steels have suc-cessfully replaced austenitic steelsand are now rmly established. Bycombining high strength and goodcorrosion resistance, LDX 2101 hasproved to be a very good steel grade

for a wide range of tanks. To maxi-

mise the benet of using thin-walleddesigns, the right welding method/process must also be chosen for theobject in question.

Small tanks

Small tanks (volume typically 0.5 – 3 m3

/ 17.5 – 105 ft3 and wall thickness1 – 3 mm / 0.04 – 0.12”) are oftenwelded using robotic or semi-auto-matic MIG/MAG. So that all weldscan be made in the best position, apositioner/rotating table is used. In butt joints and, in some cases, overlap joints too, 1.00 mm (0.039”) or 1.20mm (0.045”) diameter welding wire isnormally used (see table 4). The risk of crevice corrosion must always be con-sidered with overlap joints.

Figure 1. Fuel tank, < 1 m3

Using tandem instead of single-arc,welding speed can typically be in-creased by 50%. Tandem-arc welding

uses two separate power sources thatmay have different potentials, arcmodes and parameter settings. Usingtwin-arc welding with two wires butonly one power source, it is difcultto obtain a stable arc that is free fromspatter. The twin-wire method is notwidely used in MIG welding. With lo-wer total heat input, both tandem-arcand twin-arc give increased weldingspeeds and metal deposition rates.

Compared to, for example, laser orplasma welding, MIG/MAG is relati-vely tolerant to misalignment and root

gap variation.

Large tanksLarge tanks (volume up to 10,000 m3

/ 350,000 ft3 and wall thickness 5 – 18 mm/ 0.20 – 0.71”,) are often weldedwholly on-site using FCAW and co-vered electrodes in all positions (seetables 4 and 5). Welds are either fullpenetration from both sides (the back then being ground) or single-sidedagainst a ceramic backing.

Figure 2. Large storage tank, ~9000 m3

Joint 1

Joint 2

Joint 3

Joint 4

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Normal welding sequence:1. Top of the tank – overlap joints

welded from both sides usingFCAW in the at position andMMA or FCAW in the overheadposition.

2. The side segments are normallywelded one by one. MMA is usedto tack each formed plate. FCAW isused for circumferential welds andMMA or FCAW for vertical welds.

3. The bottom is normally welded asa single-sided butt weld against a backing strip.

Deformation must be rmly bornein mind and tacking and sequence/intermittent welding are importantconsiderations.

A weaving technique is normally

used for vertical-up welding withMMA and FCAW. Weaving width can be as much as 20 mm (0.8”). Thus,using a weaving technique instead of

Welding Welding Plate thickness Avesta fller DiameterShielding gas

method position [mm] / [inch] metal [mm] / [inch]

MMA 3G/PF 5–18 / 0.2–0.7 LDX 2101 2.5 (root) + 3.25 –

3/32 (root) + 1/8

FCAW 2G/PC 5–18 / 0.2–0.7 FCW-2D LDX 2101 1.2 / 0.045 Ar + 18–25% CO2

(20–25 l/min)

Table 4. Welding methods, general

Welding WeldingJoint preparation

Joint angles (°)

Root land, C Root gap, D

method position [mm] / [inch] [mm] / [inch]

MMA1G/PB

FCAW4G/PE – – –

(Joint 2)

FCAW2G/PC β1 = 45°

2 / 0.08 2,5 / 0.10(Joint 3) β2 = 15°

MMA3G/PF

α = 70° 2 / 0.08 2,5 / 0.10(Joint 4)

Table 5. Welding methods, joint preparation

stringer beads, the number of passescan be dramatically decreased.

ConclusionsCurrently, LDX 2101 is most com-

monly used for various types of storage tanks. The primary reason forchoosing LDX 2101 has been its highstrength in combination with a corro-sion resistance that is at least as goodas that of EN 1.4301/AISI 304.

LDX 2101® also has very good wel-dability and excellent results are ac-hieved using all common arc weldingmethods. To ensure a sound ferrite/austenite structure in the as weldedcondition, a ller that is over-alloyedwith nickel must be used. Avesta LDX2101 ller metal has been specially

designed for welding LDX 2101®

.Productivity is a major factor when

choosing welding method. The cur-rent trend is towards using the most

efcient method for each type of wel-ding, in each position.

MIG/MAG is often used for wel-ding thin structures and FCAW forthick. Small tanks (wall thickness 1– 3 mm / 0.04 – 0.12”, volume 0.5 – 3 m3

/ 17.5 – 105 ft3) in LDX 2101 have been successfully welded using robotic or semi-automatic MIG/MAG.Large tanks (wall thickness 5 – 18 mm/ 0.20 – 0.71”, volume up to 10,000 m3

(350,000 ft3) are often welded whollyon-site using FCAW and coveredelectrodes in all positions. Thus, the best welding method for storagetanks is highly dependent on size.

LDX 2101 has also demonstratedextremely great potential in a largenumber of other applications, e.g.

desalination plants, water heaters,railway carriages, dam gates, bridges,cargo tankers, various vehicle compo-nents, etc.

Welding Plate thickness WeldingJoint preparation

Root gap, D Avesta fller

method [mm] / [inches] position [mm] / [inches] metal

MIG 2–4 / 0.08-0.16 1G/PA 2.0/0.08 LDX 2101Fog 1

MIG 1–4 / 0.04-0.161G/PA

– LDX 2101Fog 1

Table 3. Welding methods, joint preparation

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