What is back purging and why is it critical in motorsport fabrication TIG welding? Purging is the process of removing the oxygen from the inside of an enclosed part prior to TIG welding. Removing oxygen from inside the part protects the back of the weld from oxidation due to the high heat of TIG welding enhancing the quality of the weld. This, in turn, maintains the corrosion resistance of parent materials, ultimately reducing leak rates and even structural failure risks of your finished work. I