Turning Gear/Vacuum Pump

What happens if nobody answers because he is not "geared" enough to the question?

A little bit more input and also an explanation on STG would be helpful.

I.

STG / Stean Turbine Generator? Sealing oil plant vacuum pump?

Regards JD.

If the STG is at ambient temperature nothing will happen - as long as the gland steam is not in peration. The conditions of start up will mismatch and therefore it could be possible you will not get permission to start the turbine.

If the STG is hot (or warm) and the gland steam is not in operation air with ambient temperature will be succed in to the outer steam glands. Also when the gland steam system is in operation and the turning gear is not in operation the temperature of the shaft will be different along the circumference of the glands and cause thermic distorsion of the shaft. Starting of the STG from this point should be avoided - high vibration coukd occure, Therefore first you have to turn the shaft as long so that the temperature along the circumferense is equal.

I agree your point....Once again i will explain my doubt clearly....

During erection/commissioning, while checking the operation of vacuum pump, i was about to start vacuum pump without STG on TG. At that time, EPC people's hasn't agreed to start vacuum pump. Reason they given was, "without STG on TG, we shouldn't start vacuum pump". Is there any logic/reason behind this?

http://www.acronymfinder.com/stg.html

http://www.acronymfinder.com/TG.html

http://www.acronymfinder.com/EPC.html

What do you call a celibate deer with no eyes?

I can't understand about vacuum pump. Anyway i will give one answer. I consider that vacuum pump is used to create the vacuum in turbine. We have to supply gland steam before create vacuum in turbine. If STG is not in TG while supplying gland steam then definitely thermal distortion occurs in rotor. I think this might be the reason for putting the STG on TG before starting vacuum pump.

This is the only right explanation.

The vacuum pump will only maintain the required ressure (vaccuum) when the gland sealing steam system is in operation. Before starting this the rotor ha sto be turned permanently to avoild hot spots in the glands causing distorsions of the rotor.

A. Harrer