I always thought the old rule of thumb for tube expansion was just shop talk.

I was reading a 1970s boiler manual from a plant in Cleveland and it said you should expand tubes to 1.5 times the tube wall thickness, not the hole diameter. My foreman confirmed it and said it prevents over-rolling. Has anyone else run into this spec in older prints?

3 comments

3 Comments

wendy2051mo ago

No kidding, those old manuals actually knew their stuff... my uncle was a pipefitter and he swore by that same rule. He said rolling to the wall thickness kept things from getting too tight and cracking later on. It makes total sense when you picture it... you're just filling the gap between the tube and the hole. Seems like a lot of that hands-on knowledge got lost when everything went digital.

oliver7721mo ago

Guess that old manual was right (who knew they actually wrote useful stuff back then). My foreman would've loved to see that.

jesse_west8d ago

@wendy205 nailed it though... those old timers figured all this stuff out through trial and error, not some fancy software. Funny how we keep rediscovering the same tricks they had in those tattered manuals from the 70s.