Steam Turbine HP Rotor Bending


Thread Starter

R B Murthy

When turbine was being restarted after a short shut-down under hot condition, there was high eccentricity (.66mm) even before the speed was reached 500 rpm. Turbine was stopped on opening up HP cylinder, it was observed that HPC Rotor had bending of .66mm close to hub of curtice wheel.

Probable cause and rememdial measures to be taken may kindly be emailed.

I don't know the type turbine you have, but it has been my experience that .66 MM is permissable on most turbines. It sounds as though the rotor was stopped for a short period and needed to be rolled out on gear. The other more critical issue would be water induction! With the bending at the first stages it is important to have the steam to metal mismatch less than 100 Degs F and the temperature of the steam increasing, on the roll up. Please contact me at [email protected] I would like to learn more about your problem.
Dear Mr. Danno,
thank you your quick response.
It is a LMZ Russian Design, BHEL make 210 MW Turbine working in one of the Power stations in Gujarat in India.
Water induction is ruled out since there was good control on drum level.Steam temperature was higher than metal temperature and was increasing.
The Turbine was being restated after a short shut down. While roll up excentricity shot up to 0.66. Hence the machine was tripped out. /When the machine was opened up for inspection severe rubbing on curtis wheel hub close to inlet nozzle box was seen. Rubbing mark was found in subsequent stages too over the shroud and tenen.
Could you throw any light on possible cause of this damage to HP rotor?

Thank You,

dear sh murthy,
the hp rotor bending is definitely due to water ingress. there are a no of reasons of water ingress, however past experiences show that the most common ones are----
1) HP heater level high and fcnrv's passing.
2)water ingress thru gland steam condenser during the start up period.
3)steam to seals parameters not ok, especially condensation in the line entering the rotor.
let me know more,
I would think that you had a severe water induction. Did you flood a feedwater heater and have it back up into the HP or IP?

0.66mm (.024") is a lot of runout. I'm assuming you'll need to throw the journals and re-machine the ODS on the rotor.

Best of luck.