Please tell me someone
As per ASME B31.3. is that necessary to perform, Stress analysis for all hot pipes.

I think that the support and pipe stress analysis is always required. There are only few exemptions given in 31.3, but to use them, you must really know the support situation well.

Background is that the Designer (check the qualification requirements in 301!!) shall not neglect the suports.

DK

Either that or you can write your own stress analysis plug-in that will simulate real life scenario. But that is a little hard as there are a lot of factors you have to consider and for your software to be recognized will take a great deal of time and patience on your part, but totally possible. It is adjust about making each parameter a sure and safe one to use and pull off.