porosity in tig root on boiler tube on a 6 g test

by phillip bunch
(jacksonville,florida)

i recently welded a boiler tube coupon on a 6 g position with a tig root,i had a little bit of push through at the top but not very much within a 16th of an inch,well wen they went to bend test it they said i had porosity in the root and i failed it,it looked awesome wen i finished welding it and was sure that i passed it,can u tell me wat the problem was?

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wtt answers,

sometimes on boiler tube and other pipe roots, you use a small diameter cup to get at the root.

it can suck air if you have the gas too high, or if you dont have it high enough you can lose shielding for a second because the gas is escaping thru the open butt root gap.

the tip is an unusual place for that to happen because argon is heavier than air.

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