uma685•2mo ago

Just passed my 5 year mark without a single weld fail on a pressure vessel

I keep seeing guys skip the full preheat on P91 steel, especially on smaller jobs like the feedwater heater we did for the plant in Tacoma. They think because it's a 'short' weld they can cheat the temp, but that's asking for a crack down the line. I've stuck to the book, hitting that 400 degrees for the full soak time every single time, and my last five inspections have been clean. What's the shortest weld you've still done a full preheat cycle for?

3 comments

3 Comments

nelson.wesley2mo ago

Yeah, my old foreman always said the steel doesn't know how long the weld is.

oscarb772mo ago

Exactly, the metallurgy doesn't care. It's wild how a tiny weld needs the same full process as a big one, but that's what keeps things from failing later.

the_nina2mo ago

Honestly, the shortest full preheat I did was on a three-inch seal weld for a superheater outlet header. It felt like overkill, but the metallurgy doesn't care about the weld length, only the cooling rate. That little weld passed UT five years later, so the time was worth it.