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The amount of guys who skip the pre-heat on a 2-inch thick plate weld is wild
I was on a job in Pittsburgh last month, and I watched a crew try to weld a 2-inch thick carbon steel plate without any pre-heat. They just started laying beads. I could hear the cracking from twenty feet away. They spent the next three days grinding out cracks and re-welding, which blew the whole schedule. It's basic stuff, but it matters because that thermal shock creates hydrogen cracks that you can't always see. I learned this the hard way on a pressure vessel repair five years ago when a weld failed hydro. Now I always check the WPS and break out the rosebud torch if it calls for it. Has anyone else had to step in and stop a crew from making this same mistake?
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christopher_craig3mo ago
Whoa, I started keeping a portable propane heater in my truck for that exact reason.
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christopherwilson6mo ago
You said "it's basic stuff, but it matters." Man, that is so true. I read an article in a trade magazine about this exact thing. They called those hydrogen cracks "delayed time bombs" because they can show up days later after the weld cools down. The article said on thick plate, skipping pre-heat is basically guaranteeing a failure. It's not worth the risk.
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sethr116mo ago
Delayed time bombs" is a perfect way to put it. People forget the hydrogen can come from the air itself, not just the rod. Ever weld in a humid garage? That moisture in the air gets into the weld pool. I saw a guy weld a trailer frame on a rainy day, no pre-heat, and it cracked clean through a week later. The schedule said it was fine, but the weather didn't.
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