Hello all,

we are encountering a strange behavior on #2 brg of a gas GE gas turbine MS5001, in fact vibration level on that bearing seems to be normal until the opening of IGV, where the exhaust temperature falls down rapidly at the same time vibration level on brg 2 go high from 3mm/s to 7mm/s than keep going up to 13 mm/s,
after about 20 mn, when turbine thermal conditions stabilize, vibration start dropping down progressively to 4mm/s after 1hr 30 mn

shaft vibration indicate 0.03 mm (displacement probe)which is ok but seismic probes (2) gives high vibration reading at 1X, confirmed by external vibroport.

please advise.

Regards.

Dear Mohzek,

I am not sure whether your problem has been solved by now. Vibration troubleshooting is always troublesome. As per your description, it appears that, you might have vibration due to unbalance. This could be caused due, load coupling alignment problem and GT base plate loosens. To give you more information, you should give us some more detailed data such as HP speed, bearing drain temperatures. The older FR5001 have also one seismic probe on the GT axial compressor casing. The new types have two seismic probes per bearing. Does the both seismic probes on bearing#2 gives the same reading? Is there any vibration differential alarm? During transient conditions genuine vibrations might be detected and sometimes the seismic probes or the armed cable can be loose. Loose seismic can give you the same kind of problem!

Tempus Fugit

Ali Oztas

You did not tell when this problem appeared?

After a cold startup, due to rapid starting.
"\

Or startup after a shutdown and thermal bow etc?

What has changed ?

Some balance weight got disloged?