Gas Turbine Tilted Pad Journal Bearing Failure

We have Siemens SGT 300 ( 7.5 MW) Gas turbine Generator.

During starting of this machine heavy vibration observed and machine tripped at 9000 RPM on high vibration ( Vibration tripping set at 90 Microns). More than 15 trial taken in this machine neglecting vibration. On opening this machine cold end bearing found damage. Photographs attached. What is probable reason for this bearing failure??

Pawan

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pawannlng posted:

We have Siemens SGT 300 ( 7.5 MW) Gas turbine Generator.

During starting of this machine heavy vibration observed and machine tripped at 9000 RPM on high vibration ( Vibration tripping set at 90 Microns). More than 15 trial taken in this machine neglecting vibration. On opening this machine cold end bearing found damage. Photographs attached. What is probable reason for this bearing failure??

Hi Pawannlng,

Why it need to neglect the vibration? could you share plot if any like shaft centerline, sequence of orbit and time signal, bode and polar possible.

When is the last time taken oil analysis prior this incident? 

regards,

RG

Dear Pawan,

Without referring the diagnostic plots i think its very difficult to pin point the root causes of the failure. For fluid film tilting pad bearings, we need to refer more plots and one plot may not give clear conclusion. My opinion, since i am practicing vibration analyst more into this type of bearings. For hydro machines this type bearings are commonly used.

Sherub

Dear Pawannlng, the possibles causes are:

1.- misalignment (external misalignment)

2.- bearing housing excentricity (internal misalignment)

3.- low lub oil pressure in bearing or any restriction in lub line.

4.- over radial load.

5.- Preload in bearing (internal or external)

we can rule out the last possibles causes using technologies that Rotating Guy said (Shaft centerline, sequence of orbit and time signal, bode and polar possible, spectrum, etc).

 

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