How to change over Hydraulic oil filter in frame6B GE gas turbine, while the Gas turbine is in service? How can we make sure that the standby filter is filled with oil without air bubbles.

Before, Gas turbine tripped on several occasions during change over. Whether both filters will be in service when the change over handle is in the intermediate position. Is it necessary to change over quickly or to move the handle slowly? Please give a reply.

 

Check your P & ID for details.

1)open the fill valve and allow stand-by filter to be full and primed (should take only a minute)

2) Change over quickly, do not stop in the intermediate position, ever..!!

3)Close the fill valve

4)If you are really worried, you can force the Low Hydraulic Pressure Trip ( should be something like L63HQL or L63HQT)just while you are changing over.

I have never tripped a machine while changing the filters, something is wrong or you are doing something wrong.

 

Bob Johnston,

I have seen some non-GE packaged units which did not have transfer fill valves, making transfer on-line iffy, at best. In those cases, it was necessary to transfer to the newly-replaced filter for a brief time--while off-line--to fill the newly-replaced filter and -canister and then transfer back to the other filter. Then there was less chance of tripping when attempting an on-line transfer--though, as you say if the transfer valve handle was moved too slowly the unit could still trip.

The P&ID should note the presence of transfer fill valves; there should be a transfer fill valve for each filter canister (usually). To use the transfer fill valve, while there is hydraulic pressure one must first open the filter vent valve then open the transfer fill valve second, and wait for a steady stream of oil without bubbles to come out of the filter vent. Then, close the filter vent valve first and the transfer fill valve second, then firmly and with conviction move the transfer valve handle swiftly to change filters.

But not every turbine has transfer fill valves. Even on GE-packaged units they were sometimes a purchased option for on-line filter transfers. It just seems to have depended on the desire of the turbine packager to provide running reliability--and at a cost the purchaser could "afford."