Gas tungsten arc welding, in which an arc from a tungsten electrode heats the work under argon or helium while filler rod, if used, is fed by hand into the pool. It gives the cleanest, most controlled welds on stainless, aluminum, titanium, thin sections and pipe roots, but it is slow and demands two-handed, often foot-pedal, coordination. Aluminum runs on AC for oxide cleaning; steels run on DCEN.
Root and hot pass in GTAW, then fill and cap with 7018, that's the procedure on the steam lines.
Grind tungsten lengthwise, with the scratches running toward the point; grinding around the circumference makes the arc wander.
Also heard as
- TIG
- heliarc
- tungsten inert gas
Related terms
Dip
TIG slang for touching the tungsten into the weld pool or filler, contaminating it and stopping the work.
Cup
The ceramic or glass nozzle on a TIG torch that directs shielding gas; also a MIG gun nozzle.
Walking the cup
TIG pipe technique of rocking the ceramic cup along the bevel to move the torch in a steady weave.
Purge
Inert gas flowed inside a pipe or behind a joint to keep the back of the weld from oxidizing.
Stacking dimes
Slang for a weld bead with even, tight ripples that look like a row of overlapping coins.