Fatigue stress computation

Hi all!
I have a doubt:
using the ASME code in CAESARII, the FAT stress is computed as a stress intensity.
the expansion stress is also computed in this way (with B31.3 for instance).
I have made a computation with the same load case defined as FAT or EXP, and the stresses computed are different.
Why?

thanks

B31.3 provides an explicit equation for the computation of the Expansion stress. B31.3 does not provide an equation for the Fatigue stress.

As explained in the Technical Reference Manual (Chapter 6), CAESAR II uses a stress intensity for the Fatigue stress. This will produce a different result than the code's expansion stress equation.