Gas Turbine Bearing Failure - Lube Oil Leakage Caught Fire

The machine is Turbo Generator , the Gas turbine is GE Frame 1.

Fire incident happened in GT side due to Lube Oil leakage either internal or external not confirmed yet. Upon inspection , the Babbitt material loss found in bearing#3 (see attached crossection ) at LP rotor. Also coke or tar found at LP bucket. All relevant pics and GT crossection dwg ED2971C5-7E8E-4715-8728-57F4E0F84C7817D7E95B-309F-427B-81CD-DA126EFDAAF5A79F207E-45B6-4C05-81F0-42E7B324FA118BE73253-AB9A-4D12-91ED-AD20403941EB894E8710-72C8-454A-AB44-7C0A5FC7FC51D20AA1A6-7D62-4B7A-9BDC-510807B5C462attached .

The questions are:

1) what’s the origin of lube oil leakage external or internal ? Is it split from bearing housing or lube oil supply pipe leakages ?

2) what’s the root cause of lube oil leakage ?

3) What’s the root cause of Babbit materials loss at Lower part of Brg#3? Pics attached 

4) how the coke or tar formed at LP buckets ? Pic attached 

Attachments

Photos (6)
Original Post

I do not have experience on frame 1 but I think you should check some information and answer for yourself that:

1. The leakage oil just happen at Bearing #3 or at all bearings?

2. Have you checked the oil drain piping for any plug/stuck? 

3. there is buffer air supplied to labyrinth seal, isn't it? if any, have you checked the buffer air lines? 

4. How about oil vapour system?

5. Have you checked the bearing temp? when is it increased? the same for vibration?

If the fire happen in the moment of GT running, i think that the oil leakage happen from internal (if from external, i believe someone seen and announced).

The bearing look like running under too high temp. The oil under high temperature (over 200oC) will form coke. 

Ngo Dinh posted:

I do not have experience on frame 1 but I think you should check some information and answer for yourself that:

1. The leakage oil just happen at Bearing #3 or at all bearings?

Total 4 bearings, All bearings Checked , only bearing#3 found with Babbitt material lost. other 3 bearings found normal.

2. Have you checked the oil drain piping for any plug/stuck? 

Yes Checked , no obstruction or Plugging observed.

3. there is buffer air supplied to labyrinth seal, isn't it? if any, have you checked the buffer air lines? 

Yes, Seal air has been taken from 10th stage of Axial Compressor, air supply lines have been checked and found normal for required seal air pressure.

4. How about oil vapour system?

Please elaborate further on this??

5. Have you checked the bearing temp? when is it increased? the same for vibration?

Under Review.

If the fire happen in the moment of GT running, i think that the oil leakage happen from internal (if from external, i believe someone seen and announced).

Fire smoke has been observed in exhaust duct of GT, soon after GT enclosure was opened and fire was seen, in 1st thought, LO Pump was shutdown and fire was removed, once LO Pump Started again, the fire happened again then again the L.O Pump was shutdown and fire removed. Fire is for sure due to L.O leakage , but still mystery from where the Oil leaked and how the fire caught? and how the L.O penetrated at LP rotor bucket and formed coking/tar since L.O Pressure is lesser than the Turbine Pressure??

The bearing look like running under too high temp. The oil under high temperature (over 200oC) will form coke. 

The bearing#3 damage looks secondary damage due to fire and dry running of LP rotor (since L.O pump was stopped)

How the fire happened , still dont know??

 

The Ventilation Fan was also tripped due to breakage of its belt which may increase the T of enclosure and which further melt the Babbitt white metal which leads to bearing failure ?? I am not sure, can u recognize from bearing pic, is it melted during running or stationary? or is it melted due to high LO temp??? I am not sure 

During inspection, the brass oil seal was found damaged. So, there is a possibility the oil could leak from Brg#4 and got fire, but question is why Bearing#4 which is near to fire location is not melted and how the fire traveled from Brg#4 towards Brg#3 ?  You know its Turbine Section , the pressure at Brg#3 is higher than the pressure at Brg#4

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