steam turbine vibration "amplitude and phase" have huge changing with load? this happened after overhauling the steam turbine. what can be the cause?

if the problem is due to steam excitation or not?
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Packzad... I do not presume to have a solution, but, perhaps an experience will shed some light! Coincident change in amplitude and phase-shift could be indicative of a vibration phenomenon referred to as the 'Morton Effect!" It is associated with tilting-pad bearings or seal-to-shaft rub. My experience was associated with the latter phenomenon.

A 21,000 Hp induction-motor, driving a refinery compressor, would trip randomly. There was no recognizable pattern, i.e., day or night, weekday or weekend, rain or shine, during all phases of the moon, the ocean tides, space-shuttle launches, etc, etc.

The problem was eventually traced to a shaft-rub occurring where the shaft passed through a wood (yes, wood) bushing mounted through the motor's fiber-glass enclosure. A slight unbalance of the motor’s rotor produced the rub, which, in turn generated enough heat to bow the motor's 6-8" dia shaft. It seemed impossible to the team assigned to solve the problem (including Prof. J.P Denhartog, considered then, the father of Vibration Analysis!)

Additional details will be furnished on request.

Regards,
Phil Corso