Porosity Tig welding mild steel

by Frank
(PA)

Frequent porosity welding steel pipe root pass

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make sure you are not using too much torch gas .

using a small cup with lots of gas flow will cause porosity.

also using too big a cup will make you have to extend your electrode too far and cause porosity.

usually a #5 or #6 cup with about 15 cfh works for a root pass but it all depends on the bevel angle and prep.