What is the main function of the back purge in GTAW?

The main function of the back purge in Gas Tungsten Arc Welding (GTAW) is to protect the backside of the weld from oxidation or contamination. When welding materials such as stainless steel or titanium, the exposure of the weld area to the atmosphere can lead to the formation of oxides and other contaminants, which can adversely affect the integrity and properties of the weld.

The back purge involves the use of an inert gas—typically argon—which is introduced to the area behind the weld. This process creates a protective atmosphere that prevents air (specifically oxygen) from coming into contact with the weld pool as it cools. By providing this shield, the back purge ensures a clean and strong weld joint, free from defects that would otherwise compromise the quality and performance of the weldment.

Utilizing a back purge also contributes to achieving consistent weld quality and is particularly critical in applications where corrosion resistance is paramount.