How to check the load case in operating condition under the coad 31.3?
I was told to input yield stress of the piping material that can check the piping in hydrostatic condition, but how to check the piping in operating condition? Is there any statement in coad 31.3 announced that 31.3 does not check operating condition? In operating load case report, there always shown the ratio is 0.0 and allowable stress is 0.0, and each time my client comment it , I can not explain it well:<

It's that question again. Check out this site for identical questions with the 'search' facility, or R.T.F.M.

Hi mingyan,
refer appendix P,it is alternative method to stress range. It addresses lift offs at operating condition.
Same effect can be obtained through Caeser Ver 5, by checking the box Appendix P.
In the stress summary you should get the operating stress based on allowable of f*1.25(Sc+Sh)
Hope this resolves your query.
regards

Try these earlier threads:

http://www.coade.com/ubbthreads/ubbthrea...h=true#Post1907

http://www.coade.com/ubbthreads/ubbthrea...h=true#Post2232

http://www.coade.com/ubbthreads/ubbthrea...h=true#Post2925

"refer appendix P,it is alternative method to stress range. It addresses lift offs at operating condition."

The sustained cases must still be evaluated even when using Appendix P and lifted off supports need to adressed during the sustained loading evaluations.... to sum up Appendix P was never intended to allow people to just go merrily along ignoring pipe supports that are incative in one or more operating cases!

thanks alot !!!

I do tend to agree with you over here that pie stress analyst shall review all the lift offs and include it`s effect. While saying efect it should be seen how much lift off has occured. Whether it is significant enough or does sagging over some time will establish the contact gain.
And then analyze the sustained W+P stresses.
But unfortunately, I have seen mistake done by guys while dealing with hot piping with frequent change in direction.

And refering to P 300 Genral a) of B 31.3 "it considers stresses at operating conditions, including both displacement and sustained loads, rather than displacement stress range only.The method is more comprehensive that that provided in Chapter 2 and is more suitable for computer analysis of piping system, including nonlinear effects such as lifts oof of support"
Hence the mention of lifts offs at operating cond in my earlier mail.

If somebody knows what he is doing, he normally won`t mistake. But the problem with us is that we are trying to analyse the system without having read of code.
Best Regards