Welding Tips and Tricks

Is there a procedure for single pass Mig welding schedule 40 socket welds for steam pipe? We will see up to 100 psi saturated steam pressure on this line.

I work for a small food manufacturer and our engineer brought in a contractor to install a new stainless boiler for our process. The pipe fitter assembled the associated piping in sch 40 stainless pipe with socket weld fittings. He seemed to have to chase a lot of leaks in a relatively small run of pipe with a lot of weld looking cold lapped. Is this an actual procedure that he just failed to perform properly (he never feathered his starts/stops so I believe that's most of his issue) or did they just throw this together?

I can't seem to find anything about GMAW on socket fittings and even came across a site where the process was not permitted. What's the deal? I feel like a lot more leaks are gonna arise in the coming months once we see some hot and cold cycling.

I've only ever tig and stick welded SS pipe. Socket welds or open butt. I do know if the procedure is allowed you can mig weld both joints. But the only time I see that done is by the guys in the fab shop who are using positioners. They build spool pieces that get field welded. But if they were chasing leaks from the start then it probably will be an ongoing issue. Could have been from bad setup or bad practice.

Good to know. Looks like bad practice for sure. They are obviously having a difficult time getting it sealed if this is what we are being left with.





Welder and settings it was left at.

Ask for a copy of their WPS weld procedure specification and Welding Certification used on your job.


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I'm with Coldman. Ask for some documentation. 100 psi steam can hurt people and equipment. Not to mention how expensive unplanned down time is . From the look of those welds on guessing they will either send someone back to redo it, or they will give you a blank stare. If you get the blank stare then you have two options. Ask them to pay someone else to fix it/ replace it. Or chalk it up to lessons learned boot them out and find someone you can rely on to fix it.

There are no pre-approved procedures for short-circuit MIG in any code that I know of. While such procedures can be done and approved on an individual basis, the "skill" shown in the pictures tells me they didn't do it. That's some amateur bullshit and has no place in live steam work.

Steve S

I have to say that looking at those welds finds me, for the first time since joining this site, thinking "I could do better than that."

And that's not a thought that comes into my mind often!




Kym