Hi ,

I am working on lines connected to multi stage centrifugal compressor and I have a question.
It appears to me that the forces and moments calculations in API617 appendix G deals with single stage compressors, if that is the case then can someone point me in the right direction for information relating to multi stage compressors calculations. I am particularly interested in finding out whether the combined forces and moments of the inlet, sidestream, and discharge connections are resolved at the centreline of the largest nozzle FACE or at the SHAFT centreline intersecting the centreline of the largest nozzle.
My understanding of this matter ,whether right or wrong is that forces and moments are resolved at the largest nozzle face for single stage compressors and at the shaft/largest nozzle intersection for multi stage compressors, I cant find any documentation to back this up therefore I look forward to your comments.

Thanks guys.

Aaron.