Low lift Oil Pressure in 9FA Gas Turbine

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Thread Starter

Mahabub

We have been experiencing low lift oil pressure in one of our 9FA Gas Turbines. Sometimes it is with one pump and sometimes with another. Every time we replace the relief valve (VR21-1/VR22-1), it remains OK for several days. But it comes again repeatedly. Has anybody experienced this problem? Any suggestion will be appreciated.
 
Mahabub,

This topic is not unique to 9Fs; many F-class turbines including 7F & 7FA turbines have also experienced the same issue.

This topic was previously covered in the following thread:

http://www.control.com/thread/1339177794

The thread was found using the search term:<pre>
"lift oil"</pre>

in the control.com Search field at the top right of the Menu bar of every control.com page. (The double quotation marks were included in the search term to combine them into a single term. This can be confirmed using the 'Search' Help section.)

Are you using the relief valves to set or control the system pressure? Because if you are, then that is probably part of the problem. Relief valves are to protect the system against the failure of the internal hydraulic pump pressure regulator (usually called the compensator). With one exception on GE-design heavy duty gas turbines, relief valves are not used to set or maintain system pressure. (The exception is units with Accessory Gear-driven Main Lube Oil pump discharge pressure; and F-class turbines don't have Accessory Gears with internal, positive displacement pumps.)

I would find it very unusual to see the setting of the relief valves to be less than the internal pump pressure regulator setting in the unit Device Summary or P&ID.
 
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Henrik Jensen

Hello,

You might be experiencing problems with varnish in the oil. Please note I'm not unbiased as this is my job, but we recently had a client who - before removal of the varnish - had problems maintaining the lifting pressure (at 3000 psi I believe, it is also a 9FA turbine) and they had to run both pumps simultaneously. Now (after the oil is free from varnish again) the pressure can be maintained using only one pump. I suggest you contact ccjensen.com and ask for a filtration unit for varnish removal on gas turbine oil. They can help you measure the varnish level in the oil (for free) as the first step.

I hope you get the turbine running smoothly again.

/Henrik
 
Hi all,

We experienced the same issue before. I think you shall check the lift oil solenoid valve because the pressure is recovered when we push the manual solenoid instead of the electrical signal.
 
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ASHUTOSH SINGLA

Pl check your VPR valve. you can also check the lift in all the bearings. If any bearing has lift below nominal value then the lift hoses may have damaged due to which the oil demand increases.
 
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