Thanks Dorin for the detailed explanation of fatigue with respect to each code requirements.

It's really not straightforward to mix match each code to evaluate fatigue.

I have read so fast and was thinking that I have to multiply stress by 2 but in this case it's divide by 2 for elbows.

Anyway, I will try to explore ASME BPVC III-1/Subsection NB, Section 3600 (Piping Design), since it's related to piping components. I have look a quick glance on that Section 3600 and it separates the primary + secondary stress evaluation with C factors and peak stress intensity evaluation with CxK factors. Looks interesting to me, maybe try to have some result comparisons for each Code. But no time for now, a bit busy with some other things.

Thanks for your expert advice.

More power!