Porosity in weld Tig root, 7018 cap

by Jay
(Canada)

Hey,

So i am welding 1 1/4 chrom with tig ER70Sb2L root, and 7018B2l cap and I am having problems with porosity in the weld. The porosity is showing up on the RT in failure levels. Just wondering if you might know where this would be coming from. I have many welders working on this job and the problem is not localized to one welder.

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It is really hard to isolate the problem from my end but here are some ideas...

high moisture in the argon (are you getting whiskers on the tip of the tungsten?)

welder using small cup with too much gas on root.

end of pipes not capped and breeze blowing thru pipe on root causing turbulence and loss of shielding.

too much cleaning of rods. ( a wipe with acetone is usually plenty...some oxidizers could be lost if the copper flashing is sanded off)

not cleaning inside of pipe enough.

using scotchbrite abrasives that leave a residue.

not wiping joint with acetone prior to welding.

thats all I can weigh in without being there...anyone else got anything?