You wouldn't necessarily have to do these by hand, but what you would have to do is define the proper conditions under which to perform the calculations.
For example, shell & tube exchanger, MAWP for tubesheet, Part UHX. When calculating MAWP for one side, what is the condition for the other side? Is it at zero pressure? Operating pressure? Design pressure? Do you increment pressure for both sides at the same time, i.e. both sides at respective "MAWP"? Pressure only conditions? Pressure plus thermal expansion?
Who knows, I won't touch it. MAWP is design pressure. Period.
Regards,
Mike