Commissioning a rebuilt 1950s GE turbine with orginal steam seal regulator.  Apparently working fine for 2 weeks, now gauge on it shows no pressure.  No steam leaking at the seals.  I suspect the guage is bad.  How can I check while online?

Some turbines are self sealing at higher loads; enough steam enters to sealing system from the high pressure end to supply the low pressure end seals.  Has the load been increased over the two weeks?  If the turbine is lightly loaded or the gland exhaust has a good vacuum, you may not see steam outside, but are you seeing higher DO?  That would indicate a loss of sealing.  Your gauge line may just be plugged with debris.  Can you safely isolate the gauge with a root valve and change it?

Is this a condensing unit, If so and if there was insuficient sealing steam you would loss vacuum.  

There should be a least a couple taps (with isolation valves availabe to to you.  More than likely the gauge you use to look at will have an isolation, then a plugged tee for installing a test guage for calibration ( or as a check guage.

You didn't say if MSTG or LSTG regulator, but in either case the feed and dump valve/globle valve are operated by one summing lever.  If that lever is level, then both are closed.

while off line or below minimun load the lever will be tilted to open the feed and supply main steam to the seal header.

Once on line and above minimun load, the HP gland leakage will back flow into the header, the regulator will sense the increase seal pressure and close the feed and open the dump valve and the lever will be tilted with the other end up.

For the LSTG, the dump valve opens with the hydrualic actuator piston down.  For the MSTG, with the actuator piston up.

IF you have any other questions related to those MHC controls, please ask

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