Welding Tips and Tricks

hi all been doing 3inch carbon steel argon root,filler and cap hunderd percent x ray butts. Five have passed no probs but on the sixth butt there was porosity picked up in the root. So repaired the butt by grinding it out and rerooting it filler and cap the affectted area . X rayed again and still porosity after the third repair and still porosity foreman decided to get new pipe and fittings the only thing i can think of is the torch is sucking in oxygen somewhere but how were the other butts all ok. All info welcome .

'repairing' porosity is ALWAYS a lengthy process. you probably left a bit in when you ground out your weld, or your grinder wheel is embedding crap in the metal. it also might be moving the metal around, trapping crap in there.

try a few more coupons from scratch. I wouldn't suspect gas contamination(either picking up air or a bad bottle) until you try some clean steel with clean filler. 5 clean plates says it's probably an isolated issue, unless the porous one was the last one. then it's at least a possibility that a hose got nicked, or what have you.

Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%. This is very lengthy process.

Hi,

Porosity with the TIG will make you rip your hair out by the root. Just when you think you've gotten it all, it bubbles up again. If I am having trouble, I some time change from a small shroud with a step down (#5) to a larger straight one (#8) with no step down. This some times can help the gas flow smoother.

Hope this helps.

Mick

Hi again,

Just a continuation of the last post. I think you asked about why you got porosity on one weld only? It can be very hard to pin down why you are getting "TIGROSITY" as I call it. I hate it when you can do a practice weld thats all good, then move on to the job and its stuffed again. Maybey a little contamination on the pipe or a breath of wind. Mabey some one with a voodoo doll stabbed you at the exact moment. Who can tell? But usually once you've got it, its there to stay, even under perfectly good weld metal. Can you get a mag particle test done on the ground out area? That might show up any holes that are to small to see.

Sorry for rambling on,
Hope it helps
Mick