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Boiler tube sheet

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Boiler tube sheet

Postby Poland308 » Fri Aug 04, 2017 4:05 pm

Tube sheet is 1-1/4 inch thick. On a 600Hp steam boiler. Runs about 100-120psi

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Two different cracks on separate sides of the boiler. Both below the water line
I have more questions than answers

Josh
Poland308
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Re: Boiler tube sheet

Postby Poland308 » Fri Aug 04, 2017 4:08 pm

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Started grinding it out but under the surface the cracks started to spiderweb. The metal Braganza to flake off as well.
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I have more questions than answers

Josh
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Re: Boiler tube sheet

Postby Poland308 » Fri Aug 04, 2017 4:09 pm

I'll post more pics after I get home tonight.
I have more questions than answers

Josh
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Re: Boiler tube sheet

Postby Poland308 » Fri Aug 04, 2017 9:23 pm

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Metal is so stressed that it cracks at the edge of the haz as it cools
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Last 1/8 of thickness started to crumble
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Welded it back out and smoothed it off
IMG_2371.JPG (52.41 KiB) Viewed 270 times
I have more questions than answers

Josh
Poland308
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Location: Iowa

Re: Boiler tube sheet

Postby noddybrian » Sat Aug 05, 2017 3:20 am

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.
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Re: Boiler tube sheet

Postby Poland308 » Sat Aug 05, 2017 8:04 am

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 have more questions than answers

Josh
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Re: Boiler tube sheet

Postby PeteM » Sat Aug 05, 2017 1:09 pm

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?
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Re: Boiler tube sheet

Postby Poland308 » Sat Aug 05, 2017 7:41 pm

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.
I have more questions than answers

Josh
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