Hi Harry,

1. If I just want to evaluate the reaction forces and moments of the pipeline, is SUS/EXP necessary? I think only actual installed/operating conditions should be considered. But SUS and EXP cases are not actual cases.

If you do not need to calculate primary and secondary stresses you would be right. But you DO need to calculate these stresses. Just go ahead and use the CAESAR II recommended cases and look at ALL the resulting calculated data. BTW there is much discussion on reaction forces and moments on this board and I would suggest that you do a search and read for a while.

2. How to get hot/cold reaction forces

Set up the Caesar II recommended load cases and for the reactions look at the operating case (ope) - look at the restraint summary report for the loadings.

....the moments after "stress relaxation" phenomenon (or "self-springing" as para 119.2 in B31.1)?

The phenomenon that you are referring to is a non-linear occurrence that cannot be duplicated by a linear elastic analysis. If you had a lot of experience in inelastic analysis you might be able to estimate the amount of "effective cold spring" that would creep into the system over a specific period (number of years) and use a CAESAR II model with estimated cold springs placed at "chosen by experience" locations. If the system had intentional cold spring at the time of fabrication and erection it would be difficult to estimate the rate of creep. And just to make things interesting, remember that every piping system ever built in the real world has some amount of unintentional cold spring (construction tolerances of 1/4 inch are typical).

Regards, John