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Heat treatment charts are fine, but your welder's real issue is the fan setting
Last week on a big drum job outside Gary, the crew kept chasing a preheat that never held steady. The chart said 400 degrees, but the surface read all over the place. I finally looked at the little box fan they set up to cool themselves off, and it was blowing straight across the joint. Pulled the fan back ten feet and added a cheap wind screen made of scrap plywood, and the temp settled within twenty minutes. Everybody argues about thermocouple placement, but airflow messes up more jobs than bad probes. How many of you actually check the breeze before you blame the gear?
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lunawilson5d ago
Airflow is one of those sneaky things nobody thinks about until theyve been fighting a job for two hours. Wind screens are cheap and easy to rig, but most crews would rather swap out three thermocouples and cuss at the chart than admit a fan or a draft is the real problem. Even a light breeze can pull heat off the surface way faster than people expect, especially on bigger joints where the mass is already working against you. That little box fan story hits close to home because Ive seen guys set up heaters next to open doors or vents and then wonder why their interpass temps keep dropping. Once you start treating the air around the weld like part of the setup, those charts actually start behaving.
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