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Seeking to develop information on the repair of holes in stainless steel expansion bellows used to seal piping penetrations on HRSG units. Any equipment, techniques or supplier/service company information would be welcome. Our units are about .008 thickness with various degrees of damage. Thanks for any help you can provide.
Wow that's thin material, I'll have to wait and see some of ideas that get posted on this one. Sorta like welding up drink cans, only they are aluminum,Huh.
Deloro-Stellite offers a Plasma Transferred Arc (PTA) powder feed system called Microstar that will do the job. Problem is that it is a bit on the expensive side for a one-time job. They have a website at:
If you start making weld repairs on the bellows convolutions, there can be serious effects on fatigue life of the bellows. Expansion bellows are designed to accomodate a certain amount of movement due to expansion and for a certain amount of time. You could wind up shortening the remaining life significantly.
You didn't say what the nature of the damage is. If the damage has occurred while in service for no apparent reason, the cause should be investigated. We have seen inservice failures of expansion bellows from stress corrosion cracking, misalignment during installation, and fatigue. If you haven't determined the root cause, any repair may be short lived.
Contact Senior Flexonics Pathway Division (formerly Pathway Bellows) in Oak Ridge, Tenn. area for service and more detailed guidance. They can send an engineer to your site and advise on repairability. Contact them at:
Senior Flexonics Pathway
115 Franklin Road
Oak Ridge, Tennessee 37830
Phone: (865) 483-7444
Fax: (865) 482-5600
I find it unlikely that you will be able to weld this thin of material with any degree of certainty. More than likely you will create more problems. When I worked at Pratt & Whitney, we welded material down to .006 but that was with an automated LASER Welder.
If the bellows is in place, one possible solution is to replace the damaged bellows with a clamshell bellows. The clamshell should be thicker (say 0.0625). You can put the two halves together and weld them. This will save on having to cut the pipe that the bellows is attached to and replacing it with a new (one piece) bellows. I assume the bellows is welded to the downcommer (more than likely to a "poison pad" on the downcommer) and the HRSG panel.
However, as Marty has stated, we now have a weld seam on two sides of the bellow, which involves the convolutions. This could have a serious effect on fatigue life of the bellows.
If the bellows is not on the unit, then I would have a new one shipped to the site from the OEM. One question, if you repair this bellow, will the OEM still warranty the part against future failures????
Just my opinion.
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