can any one explain about SRV leak test during start-up/shut-down process?

 

Vino, I am not sure of what year and model turbine you are asking about, but I will give a quick explanation of what I am familiar with, that being a Frame 7EA of the 2003 vintage.

The control system of later years runs a test of the gas fuel system during startup and shutdown. This test is actually several tests ran in series of each other.

The tests run include checking for leakage through the SRV into the interstage (area between the SRV and gas control valves, testing of the interstage which would indicate the interstage vent valve or any of the gas control valves are leaking by, and finally testing of the interstage vent valve.

Leak testing consists of closing the interstage vent and looking for pressure build-up in the interstage area, indicating the SRV is not sealing properly.

Leak testing of the gas control valves consists of closing the interstage vent valve, a very quick opening and closing of the SRV to charge the interstage, and then monitoring the pressure of the interstage for a period of time to determine if a leak may exist either through the vent or any of the gas control valves.

The last test consists of monitoring the interstage pressure after the gas leak test and verifying that pressure drops, meaning the interstage vent valve and tubing are free flowing.

Failure of any of these tests should annunciate an alarm. If a large enough leak is detected typically the start sequence will be tripped.

This is a very quick explanation, but your question was not very specific. As always I look forward to a more formal explanation from MR. CSA! If you have a more specific question to the sequence, you might get a better response.

 

Thanks for your reply & feed back...

Actually i want to know about 9FA machine leak test...During start-up/shut-down i also observed the same thing what you mentioned...In addition to SRV, ASV (Auxiliary stop valve) & Shut off valve also there in upstream of SRV... Any other test will be conducted for this two valves?

If possible, pls give the setpoint for your machine...Because i couldn't able to access the rungs..In my plant (latest version's), it is accessible to administrator only.

 

Vinu, I am sorry that I can not comment further on your question. I do not have any experience with the FA fleet.

In my controller file the logic is in the "Fuel_Gas" module, under the "GasLeakTest" task. I understand if you are unable to access logic then this is useless information for you.