TPi January 2020

welding current to the tungsten electrode and an inert shield gas to the arc zone. A collet-like clamping device allows adjustment so that the right length of electrode extends beyond the shielding gas cup. TIG welding uses a non-consumable tungsten electrode and has an extremely high melting point which means that TIG electrodes can heat other metals to their melting points without themselves melting. Argon and helium are the main shielding gases used in TIG welding. In some applications, however, a mixture of the two gases can prove advantageous. On occasion, hydrogen is mixed with argon or helium for special applications. TIG welding tips 1. A foot pedal allows the user to adjust the machine without having to turn the amperage knob and is recommended. 2. Torch position is important in TIG welding. The ideal position is 90°. However, the weld pool will be blocked from view by the torch. Angle the torch 15° to see the weld pool while maintaining great results. 3. Some TIG welding requires the use of a filler metal in the form of a filler rod when there is insufficient metal present.

make the weld brittle and lead to stress cracking and create holes in the metal; if there is too little penetration it can result in a weak weld. • Manipulation of weld pool: as stick welding is performed, gas pockets can form which can compromise weld integrity. These can be eliminated with a slight side-to- side motion when welding. • Speed of travel: a weld speed that is too slow leads to a weld bead that is too large, while a fast weld can lead to a weld bead that is too narrow. SMAW welding tips 1. Take care when handling stick welding electrodes. Rough handling can cause the flux coating to break loose from the core wire, rendering the electrode unusable. 2. Do not use an electrode if the core wire is exposed because the missing flux will cause welding defects and result in a poor weld. 3. Keep electrodes dry; wet electrodes can result in porous, weak finished welds. 4. During set up, set the amperage on the welding machine to match what is required by the electrode being used. If stick welding for the first time, set the amperage exactly in the middle of the range suggested for the electrode. 5. If using a DC machine, set the polarity according to the requirements of the electrode being used. Gas tungsten arc welding (GTAW) , commonly known as TIG (or tungsten inert gas) welding, is a versatile welding process for joining metal. Both AC and DC power sources can be used depending on the type and thickness of the metal to be welded. A TIG torch is an electrode holder that supplies

4. Torches may be air- or water-cooled.

5. GTAW is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminium, magnesium and copper alloys.

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January 2020 TUBE PRODUCTS INTERNATIONAL