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I laughed at pre-heating small welds until one snapped in the cold.
I used to think pre-heating was only for big jobs. After a weld cracked on a chilly day, I get it now! Never skipping that step again.
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ivan_perez7mo ago
Why bother with all that extra time and fuel though? Half the time it's just overkill for smaller joints if your technique is solid. I've seen guys waste a whole morning pre-heating stuff that would've held fine anyway. Bet that crack had more to do with the weld itself than the temp.
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seth2187mo ago
Ever see what happens when you skip pre-heat on thick plate? Buddy of mine figured his bead was good enough, saved an hour on the job. Whole thing split right down the seam come winter.
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michaelk237mo ago
That 1998 ASME boiler code update changed the game for a reason. They found pre-heat wasn't just about the weld pool, it drives out hydrogen that gets trapped in the steel. Your buddy's bead could have been perfect, but that hidden hydrogen embrittlement waits for the first good stress to crack. It's a time bomb, not a weak weld. Skipping it is gambling with chemistry, not just skill.
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