Changed my mind about pre-heating after a job in Cincinnati

Always thought letting a boiler cool completely before a weld was fine. Saw a massive stress crack form right in front of me on a cold start at the Miller plant. Anyone else run into this?

3 comments

3 Comments

robertb302mo ago

Yeah, that'll do it lol. Seen it happen with thick sections, the temp difference just rips it. Code might say it's okay but code is the bare minimum, you know? Always hit it with some heat now, not worth the call back.

patel.leo18d ago

You ever had to explain to a customer why their brand new weld cracked while you're standing there with a heat gun? It's not a fun conversation. On thick stuff, I always bring the part up to at least 200°F, sometimes more depending on the material. Saved my skin on a 2 inch plate repair last month, no cracks at all even after hydrotest. What do you use for your preheat, just a torch or do you have a real setup?

avery5822mo ago

Heard about a buddy who skipped pre-heat on a big pressure vessel repair. The thing split like a cheap seam the first time they fired it up, exactly like robertb30 said about the temp difference. He learned the hard way that code is just a suggestion for staying out of real trouble.