What turbine? What manufacturer? What size turbine? What country?

have you called your district service agent?

You need to regularly adjust / calibrate this valve. It is general recommended practice to calibrate this every scheduled inspection. Job normally done by control / instrumentation person.

It's MS 5001D type one shaft.

Please note that this valves were never adjusted in the other turbines.

Thank you.

Any possibility of shellac forming from the oil? We used to experience occasional problems with torque converters fitted to our Westinghouse / MHI machines where an internal shuttle would stick and oil would bleed past what should have been a closed port resulting in the machine failing to make cranking speed. When was the last time it was stripped to component level and cleaned?

This is the basic troubleshooting I would do without knowing anything else:

1. Ensure the oil temperature is the same on all units, if the oil temperature is different in this particular unit the orifice will behave differently.

2. The orifice should have a set screw to keep it in position, make sure it is locked in position - mark the position with nail polish to confirm it moves from the position it was set to.

Then:

a. If the oil temperature is not the same (+/- 2°C) troubleshoot that problem: heaters on? difference in cooling water system?

b. If the orifice cannot be adjusted, change the device

c. If the orifice maintains the adjustment, exchange the orifice to another MS5001D and confirm that the problem follows the orifice.

saludos.
a.

It seems likely that the orifice is being adjusted to compensate for some problem elsewhere. Personally I wouldn't bother moving an orifice among machines - the only thing it can realistically do is wear due to either extreme flow velocity or abrasive media, and both of those should be immediately visible.