dear friends
how should we arrange load cases according to B31.8 in following case? Is this arrangement right or not?

T,W,P,U
L1 W+P (SUS)
L2 W+P+T (OPE)
L3 W+P+T+U (OCC)
L4 L2-L3 (OCC)
L5 L1+L4 (OCC)
L6 L2+L4 (OCC)
L7 L2-L1 (EXP)
L8 L1+L7 (OPE)

would you please describe in which case should we check stress? and basically is it necessary to check stress in occasional conditions.

B31.8 changed a lot of things in the 2003 edition. It used to check the OPE, SUS, and EXP cases with some simple equations. Now it must know if the pipe is restrained or not according to the guidelines in section 833.1. In any case, it does now check the OPE, SUS, EXP, and OCC cases. To review the code stress and allowable stress equations used in Caesar, go to Help->Online Documentation->Quick Reference Guide and check out the Code Stresses section starting on page 10.

I would set up your load cases a little differently that what you have there. Here is my suggestion:

L1 W+P1+T1 (OPE)
L2 W+P1+T1+U1 (OPE) not OCC
L3 W+P1 (SUS)
L4 L1-L3 (EXP)
L5 L2-L1 (OCC)
L6 L3+L5 (OCC) use Scalar Combination under Load Case Options tab.

Thanks Loren.
But Caesar load case recommendation for this case (in B 31.8) includes L8 L1+L7 (OPE).
Can we use abs load case combination under load case options tabs instead of scalar in L6 of your load case suggestion? Would you please explain why we should use OPE instead of OCC in L2?

L2 is not a code stress case so instead of considering it OCC we call it OPE. The reason it isn't an OCC case is because it includes thermal and displacement loading, which are secondary in nature (fatigue failure). Instead we go through the process of segregating the occasional load effect and then add that to SUS so that we have all the primary loads considered for the code stress check.

Caesar used to recommend the L8 case, but in version 5 it does not since the code changes.

Loren,
I'm still puzzled! For B31.8 VIII (Offshore), how do u set up load cases to account for the Combined (Von-Mises) Stresses; does the SUStained load case take care of this?

Read this previous post:
http://www.coade.com/ubbthreads/ubbthrea...h=true#Post1624

Dear sir
load case construction in ASME B31.8 shall be performed to the following rule:

L1 WW+HP+H HYD STRESS/LOAD/DISPLACEMENT
L2 W+P1+T1+D1+H OPE LOAD/DISPLACEMENT
L3 W+P1+T1+D1+H+U OCC LOAD/DISPLACEMENT
L4 W+P1+H SUS STRESS/LOAD/DISPLACEMENT
L5 L2-L4 EXP STRESS ALGEBRAIC
L6 L3-L2 OCC ALGEBRAIC
L7 L4+L6 OCC STRESS ABSOLUTE
L8 L4+L5+L6 OPE STRESS ABSOLUTE

BEST REGARDS
A.SADEGHABADI