multiple expantsion allowable stress

Hi friends

In case of having more than one sustain load case, with different number of cycle , is that possible to have more than one allowable stress for expantion stresses?

regards

I am assuming you are using ASME B31.3.

Number of cycles does not apply to sustained cases, unless you want to consider fluctuation of pressure as a cyclic event.

I guess it is one piping system that you are dealing with so, logically it should have one governing set of allowable stresses.

If you have different numbers of cycles associated with several expansion cases, the allowable displacement stress range should be derived from B31.3 section 302.3.5 (equation 1d).

even if i consider that you have two sustained case, it will effect only the stress range only if you are using liberal stress.
rememeber the equation which has -SL, .
And if you consider 2 sustained load out of them higher Sl has to be selected for liberal stress range.
SO no worries if you ahev created case properly in Caeser
regards

Thanks for your reply

Considere we have two sustain cases which one of the with higher SL will happen only one time in entier pant life, is it logical to considere its SL to calculate the allowable expansion stress based on this higher SL which will happen only one time???

Note: this sustain case may be considered as Hydrotest ( suppose there is no hanger in the system)

Thanks

B31.3 does not have a prescribed manner for dealing with the stresses during a hydrotest it is left to the judgement of the designer "YOU" a hydrotest load is not the same thing as the sustained loads expected during operation.

Sorry Dear,
It cannot be considered as Sustained case at all.
You refer B 31.3, wher you will get a para stating the same.
Read and interpret the code, that should help you.
Hope now you have one sustained case rather than two!
regards