Alignment Rectification after process pipings are connected with Compressor nozzles results in catastrophic failure.

Care must be taken to ensure that alignment readings does not vary during alignment in both the circumstances i.e.
1) when pipe flange is not connected to compressor nozzles
2)when pipe flange is connected with compressor nozzles.
It is good practice to rectify piping and its companion flanges instead of rectifying alignment after piping is connected.This will result in catastrophic failure caused by undue loading and moments on machines casing and other internals.
There should not be load transfer from piping end to machine end after flanges are bolted with compressor nozzle in cold condition.However there may be axial and transverse loading which may occur during actual operation of plant load.This is being taken care during alignment by incorporating  axial and radial values as mentioned in OEM manual