Hello Everyone!!

I was just going through some old posts on lift-off supports check & was in quandary over solutions posted by different individuals as there was not a consensus!!

What about using Appendix P for non-linear analysis such as lift-off supports? As B31.3 explicitly states in para P300 that "The method is more comprehensive than that provided in Chapter II and is
more suitable for computer analysis of piping systems, including nonlinear effects such as pipes lifting off of supports." Therfore, Appendix P should be put on in config file for lift-off check.

Should this approach be fostered for such analysis?

How accurate are the results to the real time scenario & is this the best possible approach?

I've encountered many a times that a line which may not qualify in lift-off case (the +y restraint removal philosophy & then checking in sustained case) qualifies easily in Appendix P.

Hope you all come forward with your expert views & comments!!

Keep Smiling!!It always helps!!

SJ

Appendix P is not a complete answer to the nonlinear issue. It sidesteps the problem of setting a value for SL (the "sustained" stress) in the more-accurate limit for the expansion stress range (SA). But it requires more work in that the user must check the expansion stress range AND the operating stress state (in addition to the longitudinal stress due to sustained loads).
It's a good answer to a limited question. Unfortunately, many casual readers would assume that between CAESAR II and Appendix P, we have what we need to accurately model and evaluate real world (i.e. nonlnear) response. You still have real world variation on model parameters, design conditions, pipe fitters, and on and on.
A very sharp pencil does not improve the artist's eyesight.