Pup pieces at both end of a valve to be replaced

[pipe76]

I basically need to know what the length has to be for two pup pieces, which will be welded at both end of valve. The diameter of the pipe is 32” (774 mm) diameter and 19mm wall thickness.

I have been looking at the codes (ASME B31.3, B31.8, B31.4, etc), but I have found nothing.

I will really appreciate if someone could help to answer my question.

 

[BigInch]

No real answer to that one. Generally acceptable for most pipe is a length equal to one pipe diameter or a minimum of 6" or so. The critical considerations determining an adequate length are the possible warping of the pup if the length is too small to give geometric stability and possible overheating from the weld damaging the valve internals if enough length to provide weld heat cooling is not present.

http://virtualpipeline.spaces.msn.com

 

[pennpiper]

pipe76,
Go here for lots of discussion about "pups"

http://pipingdesigners.com/phpBB/viewtopic.php?t=47

 

[BigInch]

That was a waste of time IMO

http://virtualpipeline.spaces.msn.com