Had a flange weld crack on a boiler in a Detroit plant last winter

We were doing a pressure test on a 300 psi steam boiler after a full rebuild. I heard a sharp hiss and saw a hairline crack open up along a 4-inch flange weld I'd just finished. The whole crew had to shut down, bleed the system, and let it cool. We ground out the bad section, preheated the area with a rosebud, and re-welded it with 7018 rods. Anyone have a better method for preventing stress cracks on thick flanges?

3 comments

3 Comments

blair_butler472mo ago

Try peening the weld bead right after you finish. Helps relieve some of that stress. Also, a slower cool down with insulation can make a big difference.

jake_mason302mo ago

Slower cool down is key, we use welding blankets on big flanges.

emma_young14d ago

Welding blankets work but you gotta watch out for moisture getting trapped underneath on outdoor jobs. Had a 12 inch pipe crack on us once because we wrapped it too tight and condensation got in between. Peening can help but you gotta be careful not to flatten the bead too much or you'll work harden it. We do a light peen pass then wrap it with ceramic fiber blanket.