A WNC case run is usually made to check the displacements at the connecting flange for rotating equipments.When the displacements are very small there is no problem but for larger displacements it is difficult to tell if the pipe supporting is correct just by looking at the displacements as the strains caused on the nozzle will also be affected by size and thickness of pipes.
To make things easier for me I run two cases
wnc+h ( spring rigid)
wnc+h ( spring as designed)
If the calculated nozzle forces and moments are below acceptable limits I consider that as satisfactory.
I would like to know how the more experienced people deal with this.Any better way to do that?
Are there any industry accepted guidelines regarding the acceptable movements of the connecting flanges from the nozzle when we run WNC case for rotating equipments like pumps?
Regards
Siv

Any comments will be appreciated.

Regards
Siv

Displacement of 1 mm is allowed as per our project specification

Welding Research Council Bulletin 449 (Guidelines for the Design and Installation of Pump Piping Systems) has a good discussion of flange alignment at bolt up.