Serious question, my foreman told me to always use a 3/8 inch gap on that old boiler in St. Louis and it cracked the header after 6 months.

He said 'it needs room to breathe' but the thermal cycling was too much, so has anyone else had to re-weld a header on a 1920s unit because of bad expansion gap advice?

3 comments

3 Comments

seanh912mo ago

Wait, a three-eighths gap on a St. Louis header from the 20s? That's wild. I've seen a sixteenth work on some of those old riveted sections, maybe an eighth at most if the runs were long. Three-eighths is just asking for it to hammer itself apart every time it fires, no wonder it cracked. That's not breathing room, that's a highway for stress.

robin_foster11mo ago

Haha, 'highway for stress' is the best description I've heard all week, that clearance wasn't breathing room it was a damn interstate. @brian_jackson you're spot on about the clunking, I bet that Erie sounded like a giant angry skeleton every time the pressure came up. Honestly though, a three-eighths gap on a 20s header isn't a mistake, it's a cry for help from whoever designed it lmao.

brian_jackson2mo ago

My uncle's shop in Toledo still has the 1925 Erie they fixed after a similar gap mistake. Seanh91 is right about the hammering, you could hear that thing clunk from the parking lot on a cold start. They ended up sleeving the whole uptake to stop the flex.