When is it necessary to filter turbine oil?

Turbine oil filtration management is a core maintenance task for power plants and large rotating equipment. Similar to hydraulic systems, its requirements are unique.

The frequency of turbine oil filtration is not determined by a fixed schedule but by the condition of the oil. It follows the principle of "filtration on demand" rather than "regular filtration."

How do you determine when turbine oil needs to be filtered?

The determination of when turbine oil filtration is necessary is primarily based on oil analysis reports. Typically, turbine oil filtration requires initiation under the following circumstances:

1、Cleanliness level exceeded (the most critical indicator):

The target cleanliness level for turbine oil is typically very high, generally meeting ISO 4406 15/12/10 or better (the lower the number, the cleaner it is).

When oil particle count analysis indicates that the cleanliness level exceeds the manufacturer's specified limits (for example, deteriorating to 17/14/12), immediate filtration is necessary. This is the most direct and scientific trigger.

2、Moisture content exceeded:

Turbine oil is extremely sensitive to moisture. The target moisture content is typically < 100 ppm (0.01%), and for supercritical and ultra-supercritical units, it can be even less than 50 ppm.

When oil analysis indicates excessive moisture content, dehydration and filtration (e.g., using a vacuum oil filter) are necessary.

3、Abnormalities during routine monitoring:

Oil appearance: If the oil sample becomes cloudy or opaque, this is usually a sign of severe emulsification or particulate contamination.

Online monitoring device alarms: If the system is equipped with a particle sensor or humidity sensor, the alarm value also signals to initiate filtration.

Post-maintenance: After a unit overhaul or component replacement, the oil system must be recirculated and filtered before startup until the oil quality is acceptable.

To summarize the frequency of turbine oil filtration: For properly operating units with good seals, if the oil quality remains acceptable, additional filtration may not be required for several years. However, for older units or those in poor operating conditions (such as steam leaks), filtration may be required monthly or even more frequently. All decisions are subject to oil testing results.