Tungsten inert gas (TIG) welding is applied in all industrial sectors but is especially suitable for applications requiring high-quality joints. In manual welding, the relatively small arc is ideal for thin sheet material or controlled penetration (in the root run of pipe welds). Because deposition rate can be quite low (using a separate filler rod), MMA or MIG may be preferable for thicker material and for fill passes in thick-wall pipe welds.
TIG is also widely applied in mechanised systems, either autogenously or with filler wire. Several systems are available for orbital welding of pipes, used for example in the manufacture of chemical plant or boilers. Those systems require no manipulative skill, but the operator must be well trained. Because the welder has less control over arc and weld pool behaviour, careful attention must be paid to edge preparation (machined rather than hand-prepared), joint fit-up and control of welding parameters.
TWI possesses the following TIG welding processes:
- Orbital TIG welding
- Narrow gap TIG welding
- TOP TIG welding
- Hot-wire TIG welding