Welding Tips and Tricks

Tube sheet is 1-1/4 inch thick. On a 600Hp steam boiler. Runs about 100-120psi
Two different cracks on separate sides of the boiler. Both below the water line

Started grinding it out but under the surface the cracks started to spiderweb. The metal Braganza to flake off as well.

I'll post more pics after I get home tonight.

Is it "normal" over there to weld tubes in ? I never heard or seen anything like it - ours are always expanded - depending on the number & spacing of stays & known history for tube end erosion they're sometimes belled ( I hate that job ! ) - kinda seems like with thermal movement from cold start up & dramatic thickness difference between tube plate & tubes they're going to crack - I seen emergency welded repairs to keep an old boiler going but not on this scale.

This boiler is about 35 years old. These were expanded in and then welded. It's not very common here either. This boiler had been retubed before about 17 years ago. But I believe they were welded when it came from the factory. We were all concerned that the metal was going to be brittle and unrepairable before we started, but it's for a Hospital so we tried anyway. Going to let our weld engineers decide if they want try cutting out all the tubes and replacing the whole tube sheet.

I've done a few of those with the expander. We were warned very clearly before hand about over running/cracking them and what a pain it is to tear them out and do over. Then they got a tig root and mig cover.

Do you suppose that is what may have contributed to the failure, or are these just a matter of one every so many is going to crack and need repaired?

I've rolled in lots of tubes on lots of boilers and never had issues. I think these stem from the fact that they were welded from the beginning.