Hi,
Is it require to check nozzel loads of the rotating equipments in
SUS load case to be in accordance wiht the API?

The answer is yes.

Regards

And in occasional cases?.

I will do so if the project/company specification demands. Otherwise I will not. I admit, I cannot strongly justify the reason as the requirement of the specific standard does not differentiate between load cases.My personal argument will be that occasional case loads are most of the time too high above the allowables and it is not a cost effective exercise to bring them within the requirement all for the sake of something that "does not have a bright possibility of happening ". Also my personal feeling is that the allowable loads in standards like API 610 or NEMA SM 23 are too low, although I cannot justify my claim.I admit that these are not very"scientic arguments " as they are not supported by strong evidences but perhaps these are the best arguments I could offer.

Regards

For rotating equipment, I generally do not make major changes to a piping layout to satify nozzle loads under occasional loads. Those allowables are typically based on long term exposure and are strain limited to keep the shafts and seals from wearing out prematurely. That said, I do still check the nozzle loads to make sure that the wind or seismic event isn't going to crack the case or anything.

For equipment nozzles (pressure vessels) I will check the nozzles stresses considering the occasional loads as we are talking about a stress limited value. When you do an FEA or WRC run on a nozzle, you are computing stresses imposed. Naturally, there is still safety factor involved, but you don't want to go tearing your nozzle off the tower because it wasn't strong enough to restrain the pipe when the hurricane comes through.