Often called TIG welding is a welding process that joins metals by heating them with a tungsten electrode (nonconsumable) and a molten weld pool. The process may be used with or without the addition of filler metal. GTAW shielding gases generally include argon and helium or a mixture. Material thickness range from sheet metal to unlimited in all positions with applications such as pressure piping, vessels and other critical weldments. Material types used in GTAW include aluminum, copper alloys, nickel alloys, carbon / stainless steels, titanium and others. GTAW may be a manual, machine, semiautomatic or automatic welding process. Eye, face and skin protection are required.