DEAR CAESAR EXPERTS,

Sir I am doing stress analysis in plant piping for oil and gas projects.

I am finding one primary difference in SIF between ASME B31.3 and ASME B31.1 apart from so many other changes,that in B31.1 their is not much difference between inlet and outlet SIF's " i=0.9" we are using.

But in case of B31.3 inlet and outlet SIF,s are distinguished and their values are i(i)=0.75 and i(o)=0.9.

Sir I wanted to know the basics behind this!
why this difference exists? Even though I understand the one code is for power piping another for process piping.

Is it the maximum pressue case stands for the type of SIF values in power piping? and

Is it pressure and temperature cases stands for the type of SIf in Process piping.

Sir I have red the ARC Markel paper published in 1955,and Paulinah's reaserch paper's also.But cannot distinguish from them about this difference.

early reply will be highly appreciated.

Thanks in Advance.