The gas in orbital TIG welding protects the weld puddle and the metal transferred into the welding arc from the ambient air.
This can seem strange as oxygen, hydrogen or nitrogen are sometimes added intentionally to the shielding gases in order to increase the energy input, the visual appearance of the weld bead or the quest for specific metallurgical characteristics.
These gas mixtures are only used if the added gas does not have any negative metallurgical effect on the material.


