Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.
Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.
(OP)
Hello Everyone,
I would like to know some suggestion from experts to problem i am describing here in post.
In one of the site i was working with client they have MS-5001 (Frame-5) GE gas turbine.During the starting of gas tubine when turbine had reached 85% of the speed auxillary pump has to be stopped and main oil pump on the auxillary gearbox has to develop requied pressure of 7.5 Bar.But even turbine has reached FSNL,auxillary pump was running and MOP was not developing required pressure of 7.5 Bar.I have tried force stop auxillary lube oil pump that was motor driven through control panel.But due to low pressure developing by Main oil pump,auxillary pump was immediatly coming in line as it is in auto mode.
From mechanical end later we shutdown the machine drained the lube oil tank reservoir and we calibrated pressure control valve (PCV) on downstream end of main oil pump in workshop with pressure set point of 120 PSI and found PCV was poping off at lower pressure at less that 10 PSI.New PCV was changed calibrated before assembly at lube oil tank and an non return valve has been checked and found okWe have inspected Main oil pump and found all internal are ok.Priming was done before turbine startup.When turbine was started Auxillary gearbox Main oil pump has generated pressure and auxillary pump was switched off automatically.
But After two days from proble rectified on Main oil pump again turbine was tripped due to load gearbox Load side end bearing high vibration and it was false alarm.When every thing was reset and started turbine same problem that was before i.es MOP was not developing pressure and auxillary pump is running at FSNL.
Kindly suggest me any cause.I am attching P&ID for referance.If any details required i can share in written formate.
Regards,
Rajuuma
I would like to know some suggestion from experts to problem i am describing here in post.
In one of the site i was working with client they have MS-5001 (Frame-5) GE gas turbine.During the starting of gas tubine when turbine had reached 85% of the speed auxillary pump has to be stopped and main oil pump on the auxillary gearbox has to develop requied pressure of 7.5 Bar.But even turbine has reached FSNL,auxillary pump was running and MOP was not developing required pressure of 7.5 Bar.I have tried force stop auxillary lube oil pump that was motor driven through control panel.But due to low pressure developing by Main oil pump,auxillary pump was immediatly coming in line as it is in auto mode.
From mechanical end later we shutdown the machine drained the lube oil tank reservoir and we calibrated pressure control valve (PCV) on downstream end of main oil pump in workshop with pressure set point of 120 PSI and found PCV was poping off at lower pressure at less that 10 PSI.New PCV was changed calibrated before assembly at lube oil tank and an non return valve has been checked and found okWe have inspected Main oil pump and found all internal are ok.Priming was done before turbine startup.When turbine was started Auxillary gearbox Main oil pump has generated pressure and auxillary pump was switched off automatically.
But After two days from proble rectified on Main oil pump again turbine was tripped due to load gearbox Load side end bearing high vibration and it was false alarm.When every thing was reset and started turbine same problem that was before i.es MOP was not developing pressure and auxillary pump is running at FSNL.
Kindly suggest me any cause.I am attching P&ID for referance.If any details required i can share in written formate.
Regards,
Rajuuma





RE: Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.
On your diagram, there are several pressure measurement locations. I assume that PI-1 is the one you've primarily been discussing here? Are the others also reading low (if not, then gauge 1 is likely bad).
Which icon represents your pressure control valve? Looks like VR-1 and VPR-2 could each play a role?
RE: Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.
Gauge was correct.For information PI-1 was gauge on panel outside the machine compartment.However even if it is fauly does show correct value through calibrated transmitter data on the control panel logic (Mark-vi).
we have already checked under lube oil tank internal piping.VR-1 valve was new one and was calibrated in workshop at 80 PSI and assembled on lube oil skid 5 Days ago.
RE: Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.
1. Check for leaks.
2. Check pressure relief valve(s).
3. Check actuators (includes loads).
...
...
...
87. Check pump.
In my experience, positive displacement pumps are rarely, if ever, the problem.
RE: Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.
What piping mods did you do on the lube oil piping?
Do you absolutely know that all of your bearings are getting full-rated flow? They must be getting some oil, or they would have burned out. But, are they getting the same flow they were before the outage?
Do you have a seal oil system that may be blowing by oil or re-cycling oil somehow, or are you using a air cooled generator?
RE: Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.
We have not made any piping modification.We had visual inspection of lube oil tank at time inspected NRV and changed pressure control valve on down stream of PCV.
We are getting good rated flow for bearing header pressure always.Load with an aircooled generator.
RE: Re:Positive Displacement pump (Main oil pump) in gasturbine not delivering required pressure.