One of our customers was made aware of the elevated acceleration levels on the Motor in January 2019. Spectral content showed harmonics of running speed frequency with noticeable impacts in the waveform. Afterwards, the G4131A was taken out of operation but was run again in June 2019 without any intrusive work done on it.
The elevated bearing stress was initially recorded and highlighted in January however further step increase was recorded in June. (Please note that unit was not operation from January 2019 till June 2019.) In June 2019, sharp impacts were recorded in the Time Waveform during the vibration survey conducted.
The demodulated spectra showed harmonics of synchronous frequency which is potentially indicative of mechanical looseness or excessive bearing wear on the Motor. The customer was advised to stop the machine and overhaul the Motor which was finally accomplished in September 2019.
Running speed harmonics in spectral content and sharp impacts in the Time Domain is normally indicative of mechanical looseness / excessive bearing wear.
The unit was finally overhauled in September 2019 and acceleration levels came down to satisfactory levels.
- Through their Supporting Services Agreement, utilising portable data collection from a Scout 140-IS and System 1, this UK refinery was able to avoid unscheduled downtime and retain machine train availability for operation.
- Estimated breakdown maintenance cost saved is £20k.