TIG welding is mostly used for the welding of thin-walled pipe or plate, and for the root runs of extremely critical welded joints. It can be used either without filler metal, doing pure joint fusion, or with filler metal being added. 

Filler metal is typically added with larger thickness material. 

In this course, positional welding is divided into 3 Modules: 

4.3.1 TIG Welding - Pipe 1 
4.3.2 TIG Welding - Pipe II 

Tackle one position at a time, practice it over and over again until you are fully comfortable and versatile with welding in the position, before proceeding to the next position.