Dear Experts & Richard Sir

We are facing below situation in one of our analysis,can You guide me?

The system has Negative Temperature (Below Ambient Temp case), the supports are Lift Off in SUS Cases, & full Stress Range has been considered for analysis based on Code ASME B31.3, than APPENDIX-P is applicable to check Operating Load Cases Stresses ?

OR Which is another option to check the Operating Cases Stress?

How to consider these Lift Off supports into calculations?

Regards
SND.

you can either make an extra calculation in which you shall remove the useless supports and check your SUS case or add a load case of T and deduct it from the relevant OPE case( the same that you do for you EXP case but this time T is a primary case) checking the new case will give you a good conclusion about the sus stress of your system.
I believe this is what you are looking for.

My opinion is that there is no need to perform an extra calculation with the supports removed since they are already inactive in SUS case. But since they are active at negative operating temperature you will have difficulties in segregating the primary stress and secondary stress, therefore Appendix P seems to be the only way. This is because in your case, the primary stress is lower than the one at ambient temperature, so your EXP load case will not show the reality.

Best regards,