In gas shielded tungsten arc welding (GTAW) / tungsten inert gas (TIG) welding, an arc burning under the protection of an inert gas is used as heat source. Pure tungsten rods or tungsten rods alloyed with cerium or thorium are used as electrode. The shielding gas consists of argon, helium or argon and helium mixtures with a minimum purity of 99.95 %. In this case the shielding gas fulfils several functions. It protects the highly heated tungsten electrode against oxidation by atmospheric oxygen, cools it down and enables the formation of a stable arc. At the same time, the liquid weld pool and the molten tip of the rod are also shielded from the ambient air. During GTAW, the filler metal is introduced into the arc laterally at zero current.

Rods approximately 1 m in length are used as filler metals for manual welding and wires coiled onto rolls are used for mechanised GTAW. C-Mn steels as well as low and high-alloyed steels are welded almost exclusively with direct current and the negative pole on the electrode.From the following table it is possible to determine how high the load on the tungsten electrodes can be depending on diameter:

1.0 25 – 70
1.6 50 – 110
2.4 80 – 160
3.2 120 – 220
4.0 150 – 300

The scope of application stretches from the welding of thin sheet metal in non to high-alloyed qualities to high-quality root welding in thicker plates and tubes in these materials. The use of thoriated electrodes is not recommended since radioactive dusts are released during welding and grinding.