Expansion Joint 1

[bucs2047]

We came across a little issue with our process drains and are now forced to pipe a safety/relief valve to a common header in order avoid further damage. However in 'good engineering practice' this was supposed to be piped in order to avoid and undo stresses during operation with pipe travel. I was thinking of having a bellows expansion joint fabricated, would this be against boiler or B31.1 power piping code and has anyone come across this issue before. This is a safety valve off our FW pump with 3000 psi @ 330F.

 

[KernOily]

Not sure I understand your question. Was the SRV discharge already hard-piped to the relief header?

Since you are on the discharge of an SRV, your downstream pressure will be far below the inlet pressure so you need to first estimate the outlet pressure in the relief line when the valve goes off and then use that pressure for the bellows sizing.

I do not think 31.1 disallows bellows-type expansion joints but I would have to check to be sure.

If you look at the bellows manufacturer's catalogs, you will find their upper pressure limit.

There are other ways around this problem. If you are inexperienced in the application of bellows-type expansion joints, I suggest you hire a competent piping engineer or a very experienced piping designer to help you with this. Bellows are not to be treated lightly. They are always the last resort in addressing piping flexibility problems and can cause a heck of a lot more problems than they solve if not applied correctly.

Thanks!
Pete

 

[StressGuy]

I would definitely explore piping flexibility more before pursuing and expansion joint. 3000 psig is going to be tough to design for - your plies are going to be pretty thick to retain that kind of pressure.

Edward L. Klein
Pipe Stress Engineer
Houston, Texas

"All the world is a Spring"

All opinions expressed here are my own and not my company's.

 

[bucs2047]

Thanks guys, it seems to be the general consensus with this issue. We originally had the SRV piped to process drains under the structural foundation, which has since collapsed. This being a temp fix while we work out the details of the bigger issue. I was very much trying to avoid having an expansion loop designed because of the number of unknown factors involved with travel and undue stress on the SRV discharge.
Also B31.1 is so thorough I really think it would be a violation somewhere.

Thanks again

 

[unclesyd]

What your are proposing is possible and is done.
Check out the following website and look at the 'SAFETY RELIEF VALVE VENT CONNECTORS' brochure.

http://www.americanboa.com/lite.htm

As stated above, the advice of a competent piping design engineer well versed in the art and science of same needs to be considered.