Hello, my issue is to evaluate centrifugal compressors nozzle loads as per API 617. If suction and discharge nozzles are similar (diameters and rating are the same), the question is: which nozzle must I consider to reduce forces and moments.
Thanks in advance,

Bernardo.

Moments ... choose either.

Forces ... choose the nozzle most distant from the resolution point.

Thanks Mover Z, perhaps I was not clear. But my question is about which is the nozzle (suction or discharge) where the resolution point shall be located in these cases when both nozzles are the same sizes.
Thanks

It is convention to resolve loads on a two nozzle compressor about the suction, which is usually the larger nozzle. This accords with the NEMA SM-23 code on which API 617 is based, where the steam turbine discharge nozzle is the resolution point, being the larger nozzle. The actual location for resolution along the nozzle axis is also not too clear. The flange face is commonly used.

A four nozzle machne would normally be resolved at the intersection of shaft axis and midpoint between suction nozzles, although this is not to any Code.

It is always best to specify or agree these important details with the machine vendor, as early as possible in the design process.