GE gas turbine vibration

[DUISENM69]

We are on commissioning of GE frame 9E gas turbine and facing problem with high vibration. Can anybody tell me what is the acceptible level of vibration for this machine? During shut down it has 7.9 mm/sec on third critical speed. On base load I see max displacement 80-90 mic/pp on bearing #1 at 3000 rpm.

Thanks,

Duisen

 

[Franko]

Does GE's instruction manual give limits - as well as checks to make sure the instrumentation is working properly? For Frame 7's they usually only give alarm and trip levels for casing velocity and use shaft displacement probes for monitoring only without any guarantees.

 

[salmo]

On load or off load - what is speed at high vibration - blades on frame 9 units tend to loose parts of the trailing edge on the larger LP stages due to vortex shedding affects,also the clamp bolts for the biscuits which compose the sections tend to streatch and allow the whole assembly to get out of ballance due to the shift in interrelations.