Old timer named Bill told me to always double pass my root passes back in 2008

I was working a big boiler job outside of Pittsburgh, maybe 12 years ago now, and this old boilermaker named Bill kept yelling at me to go back over my root pass before I moved on. I thought I knew better, figured one solid pass was enough and I was just wasting time. Turns out on that job, we had a lot of thin wall tube and I got called out on a leak three weeks later. Had to cut out six of my own joints and redo them, cost the crew a whole afternoon. Bill just stood there shaking his head, didn't even say I told you so. Ever since then I always hit every root pass twice, especially on high pressure stuff. Any of you guys got a piece of advice that bit you in the rear when you ignored it?

2 comments

2 Comments

noahclark21d agoMost Upvoted

I've seen the same thing on 2 inch schedule 80 steam line, guys think one hot pass will fuse it but the backside ends up looking like crap. If you don't clean that oxide layer between passes you're begging for a failure down the road. Double pass every root, especially on anything over 300 psi, it's cheap insurance that saves you from burning a hole in your own pocket later.

bethcarr21d ago

Yeah, the "oxide layer" thing really got me. People don't realize how much that stuff can mess up a weld if you just flame right over it. I've seen guys skip the wire brushing on a root pass and then wonder why their welds are cracking six months later. A double pass on the root just makes sense, especially on steam like you said. It's a pain in the ass but it beats having to cut it out and start over. I'd rather spend an extra ten minutes now than ten hours later.