TIG Welding – Method And Application
TIG welding – Method and ApplicationTIG weldingDefinitionThe designation TIG comes from USA and is anabbreviation of Tungsten Inert Gas.If it is necessary to use filler material, it is addedeither manually or automatically as a bare wire.Tungsten - also called wolfram - is a metal with afusion point of more than 3300oC, which meansmore than double the fusion point of the metalswhich are usually welded.Inert Gas is the same thing as inactive gas, whichmeans a type of gas that will not to combine withother elements.In Germany this method is called WIG welding,the W meaning wolfram.TIG welding is the international standardiseddesignation for this welding method.According to DS/EN 24063 this welding processhas number 141.The Principle of TIG WeldingTIG welding is an electric arc welding process inwhich the fusion energy is produced by an electricarc burning between the workpiece and thetungsten electrode.TIG welding PrincipleDuring the welding process the electrode, the arcand the weld pool are protected against thedamaging effects of the atmospheric air by aninert shielding gas.By means of a gas nozzle the shielding gas is leadto the welding zone where it replaces theatmospheric air.TIG welding differs from the other arc weldingprocesses by the fact that the electrode is notconsumed like the electrodes in other processessuch as MIG/MAG and MMA.Feeding of filler material1
Migration of electrons and ions in TIG weldingThe flow of electrons from the point of theelectrode takes place at a very high speed andwhen it hits the workpiece a substantial amount ofheat energy is produced.Automatic feeding of filler materialWhen the flow of ions hits the point of theelectrode there is not produced a similar amountof hear energy.The TIG ArcAs mentioned before the fusion energy in TIGwelding is produced in the arc burning betweenthe tungsten electrode and the workpiece.The total produced heat energy is distributed byapprox. 30% to the point of the electrode that isconnected to the negative pole and approx. 70% tothe workpiece connected to the positive pole.The wire feeding can be done manually ormechanically.In DC TIG welding the tungsten electrode isusually connected to negative polarity and theworkpiece to positive polarity.Alternating CurrentAlternating current is characterised by the fact thatthe voltage changes polarity a certain number oftimes, usually 100 times per second.According to the theory of electrons thenegatively charged electrons and positivelycharged ions will migrate when the arc is ignited.The electrons will migrate from the negative poleto the positive pole while the ions will travel inthe opposite direction.In the arc there will therefore be a collisionbetween the electron and the ions and thiscollision produces heat energy.2
ApplicationAdvantagesThe TIG welding process has a very large area ofapplication due to its many advantages, e.g.: It provides a concentrated heating of theworkpiece. It provides an effective protection of the weldpool by an inert shielding gas. It can be independent of filler material. The filler materials do not need to be finelyprepared if only the alloying is all right. There is no need for after treatment of theweld as no slag or spatter are produced. Places of difficult access can be welded.Areas of applicationTIG welding is often used for jobs that demandhigh quality welding such as for instance: The offshore industry Combined heat and power plants The petrochemical industry The food industry The chemical industry The nuclear industryHeat distribution at TIF weldingThe electrode has positive polarity in a semiperiod and in the same semi-period the workpieceis negative.In the next semi-period the polarity is reversed,which means that the heat energy distributes with50% on the electrode and 50% on the workpiece.Materials for TIG weldingThe most important area of application is: Welding of thin materials in stainless steels Aluminium Nickel Nickel alloysThe increasing demands to the weld quality hasmade TIG welding very popular for welding ofsmaller tube dimensions as well as root runs inboth non-alloyed and alloyed materials in heavierplates.3
The below table shows which materials can beTIG welded and the recommended types ofcurrent and hromium/nickel steelsChromiumsteelsCopper alloysNickel ype ofcurrent Electrodepolarity- - - - - Legend: DC, AC, - negative, positiveDirect current with negative polarity on theelectrode is used for TIG welding of mostmaterials.Welding aluminium and magnesium is usually notpossible with direct current. The reason for this isthat a strong layer of oxide, which is difficult tobreak through due to its high fusion point, coversthese materials.Therefore aluminium, magnesium and their alloysare usually welded with alternating current whichis capable of breaking the oxide layer.4
TIG Welding EquipmentMany TIG welding machines are constructed insuch a way that the power source and the TIG unitare one unit.ConfigurationIn order to handle the TIG welding process andmake it work to its full capability you needequipment consisting of different parts with theirown separate function.The TIG welding equipment chiefly consists of: A TIG torch that is the tool the welder uses tocontrol the arc. A power source which is capable of providingthe necessary welding current. A TIG unit with incorporated control systemsthat make it possible to adjust the weldingcurrent, arc initiation etc. A shielding gas cylinder with pressurereducing valve and flowmeter.1234567Cable for welding currentCable for welding currentControl cable for TIG unitShielding gasCable for welding cable for TIGtorchControl cable for TIG torchWelding cable with polarityPower source and TIG unit in one unitTIG TorchThe main purpose of the TIG torch is to carry thewelding current and shielding gas to the weld.TIG TorchThe TIG torch is constructed on the basis of thewelding handle and a torch head that is coatedwith an electrically insulated material.Example for configuration of welding equipment5
The torch handle is usually fitted with a switch toturn the welding current and the shielding gas onand off.The electrode collet is split in order it cancompress to fit tight around the electrode whenthe electrode cap is tightened.1.2.3.4.5.6.7.8.9.In order to avoid a too heavy current load on theelectrode the torch is constructed in a way that thecurrent transfer to the electrode takes place veryclose to the electrode point.Torch headHandleControl switchElectrode capSealing ringElectrode colletHeat shieldCollet bodyGas nozzleDrawing of TIG welding torch6
The long torch cap, shown on the drawing, can beexchanged by a shorter version in order for thetorch to be used at restricted areas.Cooling of the TIG TorchSome torches are constructed in such a way that itis the flowing shielding gas that cools the torch.However, the torch also gives off heat to thesurrounding air.However, the cap is usually so long that it cancover an electrode of normal length.Other torches are constructed with cooling tubes.Water-cooled torches are mainly used for weldingwith larger current intensities and AC-welding.TIG torches are available in many different sizesand designs according to the maximum requiredcurrent loads and the circumstances under whichthe torch is to be used.Usually a water-cooled TIG torch is smaller thanan air-cooled torch designed to the samemaximum current intensities.The size of the torch will also depend on itscooling capacity during welding.7
Some of the new TIG torches also have a triggeron the torch handle for control of the weldingcurrent during welding.Gas LensAnother type of gas nozzle is the gas lens which isconstructed in a way that the shielding gas passesthough a wire grid in order to make the flow ofgas more stable at a longer distance.The Gas NozzleThe function of the gas nozzle is to lead theshielding gas down around the welding zone andthereby replace the atmospheric air.The gas nozzle is screwed onto the TIG torch so itcan be exchanged if required. It is usually made ofa ceramic material able to stand the massive heat.The size of the gas nozzle is often indicated by anumber that refers to the interior diameter of theorifice in 1/16”.ExampleA gas nozzle no. 4 has an interior diameter of4/16” corresponding to 6.4 mm.Flow of shielding gasThe advantage of the long gas flow is the fact thatthe electrode can have a longer stick-out thusallowing the welder to have a better view of theweld pool. By means of a gas diffuser it is alsopossible to reduce the consumption of shieldinggas.The Power SourceThe power sources for TIG welding generallyhave an open circuit voltage of about 70 to 80 V.For welding with direct current a power source isused that rectify the alternating current of themains supply of 400 V to the suitable output forthe TIG process and at the same time changes thecurrent intensity to the level set by the welder onthe welding machine.Common gas nozzle and gas nozzle with gas lensModern welding machines are capable of weldingof welding either in a DC mode or some unitsprovide both AC and DC modes.8
TIG BoxesAnother type of control of the ignition can be anincorporated unit which is capable of limiting theshort-circuit current at the moment of ignition, sothat when welding starts the point of the tungstenelectrode can be placed directly on the workpiecewithout sticking. The control then increases thewelding current intensity when the electrode islifted from the workpiece thus igniting the arc.The control system of the TIG equipment can beeither very simple or very advanced with manydifferent functions.In its most simple version only the weldingcurrent is controlled and the shielding gas isturned on/off by a small valve on the TIG torch.The more advanced TIG boxes are capable ofcontrolling the shielding gas so it is lead to thewelding place before the arc is ignited, anddelaying the interruption of the shielding gas afterthe welding current is cut off.This kind of control has several names as forinstance LIFTARC or LIFTIG.This means that the tungsten electrode and theweld pool are also protected from the atmosphericair during the cooling period.Furthermore, the TIG box usually has an ignitionfacility in order to avoid having to scratch theelectrode against the workpiece and thusdamaging the electrode point.Ignition with the LIFT method.Other possibilities for control of the ignition are: Slope control that makes it possible to preprogram the increase of the welding currentwhen welding starts and the decrease of thewelding current when welding stops. Slopecontrol is especially important at the end ofwelding to help eliminate porosity and shrinkholes.This ignition facility can be a high frequency unit(HF) which increases the frequency to 2 to 4million periods per second and the voltage toseveral thousand volts.The high frequency and the voltage make itpossible to produce a spark between the electrodepoint and the surface of the workpiece thattransfers the arc.Slope facilityCurrent pulsation means that two welding currentlevels are pre-programmed. These are pulsecurrent and base current.The base current is only large enough to maintainthe arc.The fusion of the base material then takes placewhen the pulse current is present and the weldpool cools when the base current is present but thearc is maintained.High frequency ignition9
The pulse and base current periods are alsocontrollable.When welding is done with pulsing welding modethe weld is in principle a row of spot weldsoverlapping to a larger or smaller extentdepending on the welding speed.Example of a weld with pulsing arcMany double-current machines are equipped witha control function which makes it possible tomodify the curve of the alternating current inorder to make more square, and also modify thebalance between the positive and the negativesemi-periods.Example of a modified AC curveThese control possibilities are very advantageouswhen TIG welding aluminium, magnesium andtheir alloys.10
TIG Welding – Grinding of Tungsten ElectrodesThe most commonly used types of tungstenelectrodes are: Pure tungsten is marked with green colour.This electrode is especially used for ACwelding in aluminium and aluminium alloys. Tungsten with 2% thorium is marked with redcolour. This electrode is mostly used forwelding of non-alloyed and low-alloyed steelsas well as stainless steels. Tungsten with 1% lanthanum is marked withblack colour. This electrode is equally suitedfor welding of all TIG weldable metals.Electrodes for TIG WeldingFor TIG welding the applied electrode is mainlymade of tungsten.Pure tungsten is a very heat resistance materialwith a fusion point of approximately 3,380oC.By alloying tungsten with a few per cent of ametal oxide the conductivity of the electrode canbe increased which has the advantage that it canthereby resist a higher current load.The alloyed tungsten electrodes therefore have alonger lifetime and better ignition properties thanelectrodes of pure tungsten.Electrode DimensionsTungsten electrodes are available in differentdiameters from 0.5 to 8 mm.The most frequently used metal oxides used foralloying of tungsten are: Thorium oxideThO2 Zirconium oxideZrO2 Lanthanum oxideLaO2 Cerium oxideCeO2The most frequently used dimensions for TIGwelding electrodes are 1.6 - 2.4 - 3.2 and 4 mm.The diameter of the electrode is chosen on basis ofthe current intensity, which type of electrode thatis preferred and whether it is alternating or directcurrent.Colour Indications on TungstenElectrodesGrinding AngleAs the pure tungsten electrodes and the differentalloyed ones look the same, it is impossible to tellthe difference between them. Therefore a standardcolour indication on the electrodes has beenagreed.An important condition for obtaining a good resultof TIG welding is that the point of the tungstenelectrode must be ground correctly.When welding is done with direct current andnegative polarity, the electrode point should beconical in order to obtain a concentrated arc thatwill provide a narrow and deep penetrationprofile.The electrodes are marked with a particular colouron the last 10 mm.11
The following thumb rule indicates the relationbetween the diameter of the tungsten electrodeand the length of its ground point.Blunting the electrode point to make a flat areawith a diameter of about 0.5 mm can increase thelifetime of the tungsten electrode.A small pointed angle gives a narrow weld pooland the larger the pointed angle the wider theweld pool.Flat electrode pointFor AC TIG welding the tungsten electrode isrounded as during the welding process it is soheavily loaded that it is melted into a half globularform.Example of grinding of tungsten electrodes forDC weldingThe pointed angle also has an influence of thepenetration depth of the weld.Tungsten electrode for AC weldingConnection between the pointed angle and theweld pool12
In order to obtain an extra fine grinding of theelectrodes, the use of a grinding machineespecially for the grinding of electrodes can beadvantageous.Grinding of the TungstenElectrodeWhen grinding the electrode its point must pointin the direction of the rotation of the grinding discso the grinding traces will lie lengthways theelectrode.Wrong grindingSuch machines have a rotating diamond coateddisc which makes very fine grinding traces.Usually these machines are equipped with adevice for fixation of the electrodes with anadjustable grinding angle adding to a uniformgrinding.Right grindingTungsten grinding machine13
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TIG Welding - Shielding GasFor protection of the backside of the weld it canbe advantageous to use a mixture of the reducinggases, N2/H2, the so-called backing gas.GasesThe shielding gas has several functions. One ofthem is to replace the atmospheric air so it will notcombine with the weld pool and the incandescenttungsten electrode.The shielding gases are supplied in cylinders ofsteel painted in standardised colours in order tomake them easily recognisable. For this purposethe colour of the actual cylinder and the colour ofits shoulder area is used.Furthermore, the shielding gas also plays animportant role in connection with the transfer ofcurrent and heat in the arc.For TIG welding two of the inert gases used areargon (Ar) and helium (He) of which argon is themore frequently used.The two inactive shielding gases can be mixedwith each other or each of them mixed with a typeof gas which has a reducing effect.To say that a gas is reducing means that it cancombine with oxygen.In connection with TIG welding the two reducinggases, hydrogen (H2) and nitrogen (N2) are used.ArColour of thecylinderTurquoiseColour of eBrownHeBrownBrownN2/H2Light greyRedColour indications on shielding gas cylindersxArAr/H2Ar/HeHexxxxxPressure Reducing Valve alloyedStainless steelsNon-alloyed and lowalloyed steelsThe shielding gas can be chosen on the basis ofthe material to be welded.The pressure in the steel cylinders is between 200and 300 bar. In order to use the shielding gas thehigh pressure must be reduced to a suitableworking pressure.xxxxxxA pressure-reducing valve is used to reduce thepressure. The pressure-reducing valve is usuallyfitted with a gauge where the actual cylinderpressure can be read.The choice of the correct shielding gas.15
In order adjust the required gasflow for the TIGwelding the drawing below shows a pressurereducing valve with incorporated flowmeter.Not all pressure-reducing valves are equippedwith a flowmeter. Some types have a workinggauge with a litre scale, or use a separateflowmeter.Pressure reducing valve with working manometerwith a litre scalePressure reducing valve with flowmeterIn the flowmeter there is a small ball which iselevated by the flowing gas thus making itpossible to read the gas flow in litres per minute.A flowmeter, which measures directly on the gasnozzle, can be used to control that the requestedamount of shielding gas exists at the opening ofthe gas nozzle.Please note that the measuring meter of theflowmeter must be placed vertically and that theflowmeter is designed for the used type ofshielding gas or else there is a risk for errorreadings.Direct measurement on the gas nozzle16
The amount of shielding gas depends on theinterior diameter of the gas nozzle.Indicated values for the amount of shielding gas.A too large amount of gas increases the outflowspeed in the gas nozzle. This may cause air to bewhirled into the shielding gas due to the injectoreffect.17
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TIG Welding - Personal SafetyHeat and Welding LightFor arc welding the following density of weldingfilters are recommended. These recommendationsare meant as guidelines. New examinationmethods have established those welding filterswith a density of DIN 5 provides protection ofthe eye.The light emitted from the arc is very damaging tothe eyes and may cause “arc eyes” which feelslike having sand in the eyes. The heat emissionmay cause cataracts, which is a destruction of theeyeball. The light from the arc is very damagingto the skin and may cause the same symptoms as aserious sun burn on the uncovered skin.Less than 100 A100 to 300 AMore than 300 AProtection against Light andHeatDIN 7- 9DIN 10-11DIN 12-14Shielding of the Working PlaceBy shielding off his working place the welder canprotect other persons in the room from thewelding light. Even at a distance of 10 metres thearc may cause “arc eyes”, if you look directly intoit.Welding HelmetThe welding shield protects the face and the eyesfrom heat and light and is available as a handshield or welding helmet. The shields are fittedwith dark, graded filter lens that reduces the lightand protects the eyes from the arc radiation. Infront of the dark filter is a clear cover protectingthe dark one.Working ClothesWorking clothes protect the skin against the lightand heat radiation.Types of Shielding FiltersThe types of the shielding filters have beenstandardised by the British or European standardsbut are usually supplied according to Germanstandard (DIN), Deutsche Industrie Norm. Thetype of the filter should be chosen according tothe strength of the arc, the light in the room andthe welder’s eyes. The area surrounding thewelding area must also be a suitable shade so thatthe light emitted from the arc does not disturb thewelder, but not so dark that it makes it difficult tosee the surroundings of the weld zone when thearc is established.19
Working GlovesThe working gloves protect the hands and wristsagainst heat and light. The gloves are usuallymade of leather and the top should be at least 120mm long. The gloves should be kept dry due tothe electrical safety (electrical leak resistance isgreatest at dry gloves).Arc EyesEffectFlashes from the arc and reflections from shinyobjects can cause “arc eyes”. The cornea dries upand may burst. Arc eyes feel very uncomfortable,like having sand in the eyes. Normally arc eyes donot cause lasting damage, but repetitive exposureto welding light may cause a reduction of thevision power.TreatmentCold packs offers palliation and certain ointmentswill provide a local anaesthetic. If the painpersists you should see a doctor who canprescribe an eye lotion that palliates the pain.When using such ointment or lotion willanaesthetise the eye so that grinding dust mayenter the eye without being noticed.20
Pressure Gas calOxygen,TechnicalO2ArO2Areas of applicationWelding, cutting and the likeColour of bottleCylindri- Shouldercal partpartReddish brownRG inside rightShielding gas welding of allLight greymetalsReduction- and shielding gas forLight greychemical- and metal-workingindustry. Generator cooling.Plasma welding and -cuttingCompressed airBlackWhiteInhalationBlackGaseous: Shielding gas forGreenBlackmetal-working industry,chemical industry, food industryand electro industry.Liquid: Cooling and freezingGas weldingLight blue WhiteFlame cuttingWelding, cutting and the likeLight blue WhiteCylinders under pressure must be secured againstoverturning, rolling, falling and heat (sunexposure and heat from boiler systems). Theymust be easily accessible and easy to remove incase of fire. At entrances where pressurecylinders are kept there must be a sign shownindicating hazards.Transport of cylindersCylinder should be handled in a safe and propermanner using the appropriate trolleys etc.21Connecting thread24, 32 WG outside right14 thread/inch21, 8 WG outside left14 thread/inchRG inside right24, 32 WG outside right14 thread/inch21, 8 WG outside right14 thread/inch21, 8 WG outside right14 thread/inch
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Electric Safety in TIG WeldingElectric current and risksEarth ProtectionAll machines should be earthed especially oldermachines which may not be double insulated.Electricity is a good servant, but a hard master.The electrical danger of electric arc welding isusually quite small if the necessary safetyregulations are observed.Maintenance of the Welding EquipmentThe operator should carry out daily housekeepingchecks on the welding equipment to pick upnormal wear and tear. Equipment should also bemaintained on a regular basis to ensure that it issafe to use and kept it in peak operating condition.Open Circuit VoltageWelding equipment must observe the allowedpresent open circuit voltages as indicated in thecurrent electrical regulations.Electrical Safety in TIG WeldingEquipment for manual or semiautomaticoperation: Alternating current - 80 V (effective value) Direct current ripple voltage 10% 80 V(effective value) Direct current ripple voltage 10% 100 V(mean value) Transportable equipment for private use - 70V (effective value)Power SourcePower sources with both direct and alternatingcurrent are often used for TIG welding. The opencircuit voltage of these power sources is oftenwithin the same range as that of equipment forused for ordinary arc welding with coatedelectrodes.The welding machine is often equipped with ahigh frequency facility for ignition of the arc.Mains Voltage Supply230 or 400 V is highly dangerous, but normally itis unlikely to get into contact with the mainvoltage supply.If the machine is not equipped with a highfrequency facility it can be used according to thesame regulations as equipment for ordinary arcwelding with coated electrodes. If however, theequipment is fitted with a high frequency facilitythe electric hazards are increased and it shouldtherefore only be operating in a dry environment.Defective InsulationDefective insulation of the main supply may causeleaks and dangerous contacts.23
Primary ConnectionMains ConnectionFitting of the mains connection on machines suchas welding machines must only be done by acompetent person.Two errors often occur when mounting weldingmachines: Incorrect connection of the cables Missing or incorrectly fitted cable gland.An incorrect connection can occur when e.g. athree-pole cable is connected to the three clampsof the welding machine. A phase and an earthconnection could be mistaken, so that the machinecasing could be alive, and it would then be highlydangerous to touch the machine.24
Secondary ConnectionCables and ConnectionsAll cables and connections must be insulated. Thismeans that all connections should be made withinsulating straight-through joints and not like it isoften seen, with metal cable rings tightenedtogether with a bolt screw.If the insulation of the cable is ruined, the cablemust be discarded or the insulation repaired. Inelectric arc welding it is important that the cablecross-section is sufficiently large throughout theentire circuit.Too thin cables with torn cores or poor switchesmay cause both an unstable welding current andunintentional heating which may have disastrousconsequences.25
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TIG Welding - Fumes ProductionOzoneOzone is produced when the oxygen of the air isexposed to ultraviolet radiation, as is the case withTIG welding. There are only a few differentwavelength ranges within the UV-radiation thatcan produce ozone. The most efficient part of thewavelengths between 130 and 175 nm will becompletely absorbed in the closest air layerimmediately outside the shielding gas, and largeamounts of ozone is produced. This is happeningbecause of the high absorption in the oxygen. Inthe shielding gas there is no absorption andtherefore no production of ozone. The TLV ofozone is 1.0 PPM.General Information of WeldingFumes and TIG WeldingAt a first glance there are no fumes production orvery little fumes to be seen when TIG welding.But that should not lead us to think that TIGwelding does not produce any unhealthysubstances.Different factors influence on the concentration ofunhealthy substances in the inhaled air, e.g. thecurrent intensity, the steel quality (unalloyed, lowalloyed and high-alloyed steels) and the cleaningof the materials of for instance cutting lubricantsand anti-corrosives.Welding Fumes and GasesNitrous GasesWhen welding with shielding gas smallerconcentrations of nitrous gases are produced. Thegases are produced because of the stronggeneration of heat, which is a result of thechemical reaction between nitrogen and oxygen.Nitrous gases is a common name for a group ofelements which are also called nitric oxides ofwhich there are several different ones.Only two of these have a fixed TLV (ThresholdLimit Value). The TLV of nitrogen oxide (NO) is25 PPM. The TLV of nitrogen dioxide (NO2) is 3PPM.Opposite the nitrous gases, ozone can be detectedby its very characteristic smell. Even in lowconcentrations ozone feels strongly irritating onthe eyes and respiratory passages. It may causeheadaches and fatigue and after a longer period ofexposure the pulmonary function will be reduced.If nitrogen oxide and ozone is mixed (as it is thecase when TIG welding) they produce nitrogenpentoxide which is more toxic that the othernitrous gases.Nitrous gases only feel faintly irritating and it istherefore harder to discover in due time. Whenexposed to concentrations more than the TLV thissubstance may cause instant and highly dangerousdamages to the lungs, e.g. pulmonary oedema andthe pulmonary disease emphysema.Iron OxideIron is the most important element in steel. Theheating of iron produces fumes with a content ofiron oxide. Inhalation of large amounts of ironoxide may cause reduced pulmonary function.27
indicated in PPM (parts per million) cm3/m3 or inmg/m3.ManganeseManganese is set free by welding in steels withmanganese e.g. non-alloyed and low-alloyedsteels. Manganese influences on the brain causingsymptoms such as headaches, weakness, loss ofappetite and sleeping problems.The TLVs are based on the present knowledge ofthe influences of the elements. If new knowledgemakes it appropriate, the present TLVs will berevised. TLVs are not to be considered strict limitsbetween harmful and not harmful concentrations,as such limits do not exist. It should not beconsidered adequate to merely reducing the airpollution to the level of the TLVs.Manganese is harmful to the respiratory passagesand increases the risk of pneumonia. Highconcentrations may cause metallic fumes fever.ChromiumChromium is set free during welding in low- andhigh-alloyed steels. A distinction is drawnbetween chromium 3 and chromium 6:Even though a concentration of a particular airpollution corresponding to the TLV of the elementin question will normally be harmful to the health,it should nevertheless always be a goal to keep theconcentrations of the air pollution as far below theTLVs as possible.The threshold limit value of chromium 3 is 0.5mg/m3.The threshold limit value of chromium 6 is 0.02mg/m3.Exceeding the Threshold Limit ValuesIn general the TLVs indicate the highestper
The main purpose of the TIG torch is to carry the welding current and shielding gas to the weld. TIG Torch The TIG torch is constructed on the basis of the welding handle and a torch head that is coated with an electrically insulated material. 6 The torch handle is usually fitted with a switch toFile Size: 2MB
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TIG welding is a skill that needs to be developed over time, with a piece of metal in front of you and with a welding torch in your hands. TIG welding requires patience and practice.File Size: 485KB
In TIG welding, the primary functions of the arc is to supply heat to melt the workpiece and any filler metal which may the principle features of TIG welding . an introduction to TIG welding page 5 of 8 www.weldability.com support@weldability.com be necessary. This filler metal is fed manually into the molten pool at its leading edge.
KLUTCH Mig/Stick 220Si, or other welders capable of TIG welding and use a 10-25 Dinse Style connector. This is an air-cooled 17V style TIG torch and can be used for TIG welding up to 150 amps. TIG welding does require the use of
Hand Amptrol (Rotary Track Style) – Provides 25 ft. (7.6 m) of remote current control for TIG welding. K963-3 Canvas Cover K2377-1 TIG PTA-9 TIG Torch – 125 amp air-cooled torch with 12.5 ft. (3.5 m) one piece cable assembly K1781-1 PTA-17F TIG Torch – 150 amp air-cooled
6.3 Mechanised/automatic welding 114 6.4 TIG spot and plug welding 115 7 MIG welding 116 7.1 Introduction 116 7.2 Process principles 116 7.3 Welding consumables 130 7.4 Welding procedures and techniques 135 7.5 Mechanised and robotic welding 141 7.6 Mechanised electro-gas welding 143 7.7 MIG spot welding 144 8 Other welding processes 147 8.1 .
