Is a commonly use high quality welding process.  In TIG welding, an arc is formed between a non- consumable tungsten electrode and the metal being welded.  Gas is feed through the torch to shield the electrode and molten weld pool.

Tungsten Inert Gas (TIG) Welding

Uses the heat generated by an electric arc struck between a non-consumable tungsten electrode and the work piece to fuse metal in the joint area and produce a molten weld pool. The arc area is shrouded in an inert or reducing gas shield to protect the weld pool and the non-consumable electrode. The process may be operated autogenously, that is, without filler, or filler may be added by feeding a consumable wire or rod into the established weld pool. TIG produces very high quality welds across a wide range of materials with thicknesses up to about 8 or 10mm. It is particularly well suited to sheet material.