Why Your PWHT Pads Keep Creating Hot Spots

Why Your PWHT Pads Keep Creating Hot Spots Even When the Controller Says 620°C I’ve spent twelve years on fabrication yards and plant turnarounds around Shanghai—mostly pipe shops in Baoshan, Songjiang, and the outer chemical parks—watching post-weld heat treatment on carbon and chrome-moly welds. The complaint that shows up most is not that the ceramic pad won’t heat. It’s that the hardness readings or the temperature chart look uneven, one side of the weld is soft, and the crew blames the controller or the thermocouple. Nine times out of ten the flexible ceramic heating pad has crushed or...