IN LINEWELDING OF STAINLESS STEEL PIPES

Speed up your process.

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SAF, a company of the AIR LIQUIDEGroup, has always beena leader in supplying automatic TIG & PLASMA weldingsystems throughout the world. TIG (GTAW) is the most popular process for high quality welding of stainless steel tubes.Research and development at SAF, our experienceand close contacts with customers over the years, has allowedour Group companies to offer to this specificmarket, a range of dedicated weldinginstallations best suited for the application.While a single TIGwelding system runs a process that remainsslow, it is low costequipment, that mostusually copes with existing forming lines. The addition of a second arc, TIG or PLASMA, will allow higher performance. Optimum results can only be achievedwith our well knownTRICATHODE sets.

PIPING:• Nuclear power industry.• Chemical.• Petrochemical.• Synthetic chemical.• Boilers

and heat exchanger.• Water treatment.• Air conditioning.• Exhaust gas converter,

muffler.• Off shore.• Cryogenic.• Shipbuilding.• Bio, food, wine and dairy.• Military and aeronautic.

STRUCTURE:• Industrial building.• Commercial.• Center.• Ship walk-ways.• Special structures.

ORNAMENTAL:• Door, window.• Fence, gate.• General railing.• Furniture.• Decoration.

Generally speaking, one can distinguish between pipes for industrial piping, and those for ornamental and mechanical tubing.

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The needs and expectations of tubes MillsObviously, all tubes Mills need to weld faster, at the highest quality level, without downtime. But, depending on the application of the final product, the manufacturing chart will be different, as well as the expectations in results of the various tests.The choice of the welding process and the system to run it, for the return on investment, will have to take into account, at least, the product itself, but also the production quantities, and the forming conditions.In other words, no need to invest in a laser system for thick wall pipes, manufactured in small batches, or, no need to select a high tech multi TIG system, if the speed increase may be spoilt by a poor mill, and subsequent poor forming.Whatever your requirement in terms of productivity of your equipment, SAF can offer a dedicated and standard product.

Market structure

Mill locations in the world

Welded pipe cost structure

Europe 29 %

Others 2 %

America 15 %

Asia 35 %

Japan 19 %

Material 70 %

Overhead 6 %

Deco Structure 23 %

Exaust pipe 17 %

Others 12 %

Investment 15 %

Labor 9 %

Corrosion Food 43 %

Heatexchange 5 %

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In line welding of stainless steelstubes:Welding processesOne could think that any TIG set can be suitable for in line Stainless Pipe welding...but it is too often wrong, as incompatible with your targets.When you are sure that your obvious expectationsare fulfilled (reliability, service,power, etc.) the key decision factor in the welding systemchoice, is its coherence with the mill, its peripheralequipment and the initial batch sizes.The SAF philosophy is to first select, in its large range of equipment,those having proved their performances under intensive use, which are generally machinesespecially designed for automatic applications only.Theoretically, if all the production parametersremain perfectly steady, there would be no limitation in the welding speed, except for the maximum speed of the mill itself: which is the main reason why the TIG process remains the most popular, and not laser welding for example.One way to get free from parameter fluctuations, is to concentrate the weldingenergy where it is necessary, i.e., along the joint. This is the reason why a singleTIG set is often far from the optimum solution: a “free” arc, smooth current must be limited in power to avoid the melted metal collapsing, and anyway, an excessive Heat Affected Zone.A magnetic arc deflection/oscillation and pulsed currents can improvethe overall performances of a TIG set. Then, a propercombination of several arcs will show the benefit of the basic process versatility.

TIG arc:

Plasma arc:

Dual flow manual torch:

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Typical performances

Process positionning

Running cost

Performance / investment

E 16

E 25

E 25 / TIG + PLASMA + TIG torches assembly

Tubethickness

m/min.

15

10

5

0 1 2 3 4 5 6 7 8

LASER 6 kW

Possible Recommended

TRICATHODE

Possible Recommended

TIG

Possible Recommended

Tricathode TIG DC Laser

> 400.000 $< 100.000 $

High

Performance

Average

PoorInvestment

per meter of pipe :• 5 years R.O.I (2 shifts),• 40 hours

launching batches,• wall thickness

from 1.0 to 3.0 mm.

TIG DC TRICATHODE LASER

Labourcost

Weldingset cost

Millcost

$

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The first selection criteria is the robustness and reliability,to guarantee a continuous service, non stop, day after day.Then, the arc characteristics, i.e.:• A suitable variable ripple

current (Theoretical DC) for the TIG process, thereforea machine with choke adjustment.

• Or, for the pulsed TIG process,an efficient fusion/penetrationand solidification phase, so,waves as square as possible, at large ratio between the base and the crest current: It involves an adapted choiceof transistors (MOSFET), and a particular way to controlthem (Chopper design), in order to get the fastest response time, to the currentfluctuation. Precautions will have to be taken too, in the design of the secondary circuits, so not to loose the benefit of the square wave current by inductance effect: Almost true square waves are easy to generate in the control circuits, but more difficult to obtain at the outlet of the power supply, but, in the arc where they are needed.The last selection criteria is the cost.

Considering the global investment(mill/sets of rollers and welding set), a more expensive welding system, which actually provides quality at high speed,would pay for itself within a short period of time.For the above reasons, SAF excludes Thyristormachines with a too low dutycycle, or only design for MMA. We exclude also,Transistor machines, Invertertype, and even more, thoseusing IGBT components, due to their low responsetime, and hypothetical reliability under intense use.Transistor machines, of the Linear Amplifier type,are probably the best technicalsolution in term of responsetime, but their high cost(Machine itself and primarycurrent consumption) and their difficultyto withstand the industrialenvironment, mean that the R.O.I. will be achievableonly on a restricted range of equipment.The following data summarisethe pro’s and con’s of the most common technologies used today for welding power supplies.

Power supplies, selection criteria.Not any DC power supplies are suitable for these applications.

Technology Servicing Efficiency Cost Weight SAF Equipment example

Thyristor à à à à à à à à à à NERTINOX TH 500

GTOThyristor à à à à à à à à -

Inverter MOSFET à à à à à à à à à à à à à PRESTO 165

Inverter IGBT à à à à à à à à à à à à à à PRESTO 135

Chopper MOSFET à à à à à à à à à à à à à NERTAMATIC 300 TR

Linear Amplifier à à à à à à à à NERTAMATIC 51

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In our large range of power supplies, we have consequently selected the following machines.

A wild choice of standard combinations

Typical applicationsand SAFrecommendations

Heavy duty: NERTINOX TH 500Rectifier, SCR technology, especially designedfor automatic applications (in the early eighties) with an arc characteristic specifically adapted to the Plasma welding process.

Traditional: BUFFALO 500 DCRectifier, SCR technology, design mostly for MMA or manual TIG, with proved reliability under the most difficult conditions:tropical climate, high humidity, even with long welding cable (outdoor work, on site pipeline laying or shipbuilding).

High tech: NERTAMATIC 300 TRRectifier, transistorised programmable source,chopper technology and built from MOSFETcomponents. The transistor switching speedallows to deliver an efficient pulsed current from 3 to 300 Amps at 500 Hz (maximum theoretical frequency: 1330 Hz).

Three phase supply voltage 230 - 400 - 440 Volts50 - 60 Hz

Maximum primary current at 100 % under 440 Volts 35.5 AmpsMaximum secondary current at 100 % 350 AmpsProtection class IP23Insulation class HNet weight 180 Kg

Built-in pilot arc source 10 to 12 AmpsThree phase supply voltage 220 - 380 - 415

380 - 440 - 500 Volts50 / 60 Hz

Maximum primary current at 100 % under 440 Volts 32 AmpsMaximum secondary current at 100 % 500 AmpsProtection class IP23Insulation class HNet weight 450 Kg

Current adjustable in a single range 0.06 to 10 volts,or for an output current of 3 to 500 Amps. 4 to 20m AmpsBuilt-in pilot arc source 0.3 to 25 AmpsThree phase supply voltage 220 - 230 - 400

415 - 440 Volts50 / 60 Hz

Maximum primary current at 100 % under 440 Volts 14.5 Amps

Maximum secondary current at 100 % 300 Amps(average current)

Protection class IP23Insulation class HNet weight 245 Kg

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Options:• 9121 2030: Magnetic arc

deflection and oscillation• 9257 2405: Filler wire supplyAny plasma or TIG set can be combined with one other TIG set, to make a twin torch system. Note that, when a 3 arc system is required, it is economically and technically more viable to select a dedicated system, as follows:

Note:On any system supplied by NERTAMATIC TRpower supplies, when needed (above 300 Amps 100 %), it is possible to replace one or two power sources, with NERTINOX TH 500.

* mill state... we mean its capacity to provide optimum forming, cutting, joint maintaining under the torch, and eventual polishing at high speed.

à Monotorch installations

The SAF offer, that is also:• in addition to the AIR LIQUIDE world network,

specialised partners, as TONLIN ENTERPRISECO.LTD in Taiwan R.O.C.

• close relationships with tube mill manufacturers,as DREISTERN in Germany.

• a Market Manager.• a team of specialised SAF engineers,

stationed in France and Singapore.• For 30 years, more than 200 systems

in operation world-wide.

Process Torch Power supply Capacity Technology Part Number Standard offer

GTA MEC 4 BUFFALO 350 Amps Thyristor 9121-1049 LC 03 011E

GTA MEC 4 NERTINOX TH 500 Amps Thyristor 9121-1012 LC 03 016E

GTA MEC 4 NERTAMATIC TR 300 Amps Chopper 9121-1024 LC 03 017E

PAW SP6 BUFFALO 350 Amps Thyristor 9121-1046/7/8 LD 04 016E

PAW SP6 NERTINOX TH 500 Amps Thyristor 9121-1023 LD 04 008E

PAW SP6 NERTAMATIC TR 300 Amps Chopper 9121-1043 LD 04 007E

à Tricathode installationsProcess Torch Power supply Capacity Technology Part Number Standard offer

TTT E 16 BUFFALO 3 x 350 A Thyristor 9121-1040/1/2 LE 05 022E

TTT E 25 BUFFALO 3 x 350 A Thyristor 9121-1036/7/8 LE 05 021E

TTT E 16 NERTAMATIC TR 3 x 200 A Chopper 9121-1053 LE 05 024E

TTT E 25 NERTAMATIC TR 3 x 300 A Chopper 9121-1052 LE 05 023E

TPT MEC4/SP6 NERTAMATIC TR 3 x 300 A Chopper 9121-1054 LE 05 042E

TPT / TTT MEC4/SP6/E16 NERTAMATIC TR 3 x 300 A Chopper 9121-1055 LE 05 041E

TPT / TTT MEC4/SP6/E25 NERTAMATIC TR 3 x 300 A Chopper 9121-1056 LE 05 040E

à ExamplesMaterial Thickness (mm) Application Mill state (*) Recommendation Basic P/N

300 series 0.5 up to 1.2 ornamental poor single MEC4 BUFFALO 9121-1049/50/51

300 series 2.0 up to 4.0 ornamental poor single SP6 BUFFALO 9121-1046/7/8

300 series 1.0 up to 2.5 ornamental poor E25 Tricathode BUFFALO 9121-1036/7/8

300 series 0.4 up to 0.7 chemical good single MEC4 NERTAMATIC 300TR 9121-1024

300 series 2.0 up to 4.0 piping average SP6 + MEC4 NERTAMATIC 300TR 9121-1043 +9121-1024

300 series 2.0 up to 8.0 piping good MEC4/SP6/MEC4 NERTAMATIC 300 TR -

300 series 0.7 up to 1.5 ornamental average E16 Tricathode BUFFALO 9121-1040/1/2

300 series 0.7 up to 1.5 piping good E16 Tricathode NERTAMATIC 300TR 9121-1053

300 series 1.2 up to 2.0 ornamental / piping average E25 Tricathode BUFFALO 9121-1036/7/8

300 series 1.2 up to 2.5 ornamental / piping good E25 Tricathode NERTAMATIC 300TR 9121-1052

300 series 0.6 up to 4.0 piping good E16 + MEC4/SP6/MEC4 NERTAMATIC 300TR -

300 series 1.2 up to 8.0 piping good E25 + MEC4/SP6/MEC4 NERTAMATIC 300TR -

400 series 1.2 up to 2.0 muffler average E25 Tricathode BUFFALO 9121-1040/1/2

400 series 1.2 up to 2.0 muffler good E25 Tricathode NERTAMATIC 300TR 9121-1052

Titanium 0.7 up to 1.0 nuclear good E16 Tricathode NERTAMATIC 300TR 9121-1053

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MEC4TIG Torch.500 Amps / 100 %.Water cooled copper nozzlefor efficient gas protection.Auxiliary electrode for ease of striking.Straight or elbowed version.

SP6Multipurpose tool (Plasma/TIG/dual flow).380 Amps / 100 % (Plasma)480 Amps / 100 % (TIG).Water cooled nozzle, tip,and electrode.Micrometer adjustment of the tip / electrode distance.Electrode centring device.

TPT in one shoeCombination of 2 MEC4 and one SP6 torches brought together in one shoe.Typical application : Same wall thickness than above, but necessary when a seam tracking device is needed.

Mechanical seam tracking deviceA free slide, controlled by an adjustable roller, inside the joint opening, replacesthe main mechanical transversaladjustment slide.

E16Implements the dual flow Tricathode process.200 Amps per electrode (total 600 Amps).Independent adjustment of each electrode to the shoe (one piece design).Fit tungsten 2.4 mm Dia.

E25Implements the dual flowtricathode process.400 Amps per electrode (total 1200 Amps).Independent adjustment of each electrode to the shoe (modular design).Fit tungsten 3.2 and 4.0 mm Dia.

TPT COMBINATIONCombination of 2 MEC4 and one SP6 torches.The whole assembly is adjustable to the joint in any direction, and eachtorch is independently adjustable. On the samerange of application, this system will be preferableto the E25 torch when the quality in particular, when the weld profile and penetration shape are the major selection criteria.

Torches:The key element in anyautomatic welding system is the torch. It has to be a high qualitytool that bringsquality, reproducibility and user friendliness.Because at SAF we areconscious of these points, we have developed progressively, these tools over the years, listening to our customers, to design quality torcheswith care and expertise, that can sustainrugged environmentalconditions.

Laser seam tracking deviceOn the same principle, a transversal motorised slidecontrols the torch assembly to the joint, thanks to the signalanalysis of a laser head, set up in advance of the torch.

Optional

Torches Part Number Typical application(Wall Thickness)

MEC 4 9257-9718 0.5 to 2.5 mm

SP 6 9257-2745 2.5 to 8.0 mm

E 16 9257-9633 0.5 to 1.5 mm

E 25 9257-2600 1.0 to 3.5 mm

TPT Combination - 2.5 to 8.0 mm

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The strict impurity controle of ARCAL gases will increase the life time of the electrodes in a significant way and may be extended to +100 % of the actual values (up to a complete shift).

The right maintenanceof your gas circuit,as well as the right choicein purity controlledshielding and processgases will help youto decrease frequentmachinery stops due to erosion of the electrodes.The impuritycontrolled ARCALshielding or back-shielding atmosphere will giveyou brilliant andshiny welds evenwelding sensitivealloys as “Titanium”.

Post-weld treatmentsYour welded tubesare submitted to heat treatmentsafter welding.AIR LIQUIDE will provide you withfully atomized solution for the generation and control of heat treatment atmospheres: ALNAT.

Cylinders

Racks

In bulk

Gases for “in line” welding of stainlesstubes:You need to achieve the best performances for your Tricathode welding machine, the optimum quality (penetration, aspect)and speed.You need furthermore to decrease your overallcosts (spare parts, maintenance...)The AIR LIQUIDE Groupcan provide you with a complete gas solutionenabeling to get the maximum performanceof your process.

The process and shielding gas selectionAustenites Ferrites Titanium

Central gas ARCAL 1 ARCAL 1 ARCAL 1

Shielding gas ARCAL 10 / 11 ARCAL 1 ARCAL 1NOXAL 3 / 4 ARCAL 32 -

Backshielding N2 / ARCAL F1 ARCAL 1 ARCAL 1N2+H2 / ARCAL F2 - -

ARCAL 10 NOXAL 3 NOXAL 4 ARCAL 11

Welding speed à à à à à à à à àTolerance to preparation à à à à à à à à àWetting à à à à à à à à àPenetration à à à à à à à à àRoot penetration shape à à à à à à à à à àWeld pool aspect à à à à à à à à à àElectrode life time à à à à à à à à à à

Your AIR LIQUIDE and AIR LIQUIDE Welding specialistwill help you to find the best solutionfor your process in order to provideyou with the optimum performances.

Electrode life time

Dedicated gas installation and ARCAL shielding gas

ARCAL shielding gas

Standard shielding gas

ppm pollution of shielding

Available packaging:

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Imagine what your performance could be

SAF - 13, RUE D'EPLUCHES - SAINT-OUEN L'AUMÔNE - 95315 CERGY-PONTOISE - CEDEX FRANCETEL. : +33 1 34 21 33 33 - FAX : +33 1 34 21 31 30

E mail : info.saf@airliquide.com © S

AF

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