Please discuss what is the maintenance frequency of Pressure regulating valves VPR1 and VPR2, present in lube oil tank of GE Frame 5 Turbine. Or we can only check their diaphragms in outage, as space is very limited to pull out the whole valves?
Your GE Maintenance manual gives recommendations for maintenance of general instruments like Pressure Regulating Valves or maybe you have an in company policy for the same.
For me Predictive maintenance is better for evaluating the operation of the L.O. system. Is the Turbine Bearing Header pressure stable and at the correct pressure throughout the Load range? To be honest these are instruments that, once they are set up, are very reliable. If you really feel that you need to do something and the system is operating OK, I would wait until a Major Overhaul and remove the valves, take to the workshop and check. Again there is good details on the valves in the Spare Part manuals.