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Gas and steam turbine extended service analysis

Gas turbine blades

This extended service analysis helps determine oxidation stability, identify potential varnish buildup and monitor system condition.

Description

Using lubricant analysis to monitor turbine performance can help improve unit reliability and maintenance metrics. This service offers a more extensive level of testing designed to support equipment reliability decisions for critical turbine applications.

Extended service turbine analysis provides comprehensive data that can be paired with visual inspections and operational knowledge to help determine oxidation stability, identify potential varnish buildup and ensure proper system performance.

Test Purpose Importance of test
Total Acid Number (TAN) To measure acidic oil oxidation byproducts An elevated Total Acid Number may indicate increased oil acidity resulting from increased oil oxidation.
Demulsibility To measure the ability of an oil  to separate water Steam turbines often expose the turbine oil to water from condensed steam. The ability of the oil to shed water will have a direct impact on its long-term oxidative stability and equipment rust
Foam Sequence I To measure the potential of an oil to build and maintain foam Foam can lead to operational issues like improper oil level indication or reservoir overflow
Membrane Patch Colorimetry (MPC) To measure color change of a filter patch due to varnish vs. clean patch as energy change (ΔE) Color and light blockage from lubricant deposits on a membrane patch can indicate the presence of varnish in the oil
Metals To determine the presence and levels of metallic content in the oil, including contaminants and wear particles The level of wear metals helps determine if equipment components are wearing or if harmful contamination has entered the oil. The level of metals that are part of the additive chemistry is also reported
Particle Count Analysis To measure the level of particulate contaminants in the oil
  • Cleanliness is a critical factor in the running of turbine oil systems
  • Debris can interfere in the fine tolerances of the systems, pumps and valves or cause premature wear
Particle Qualification (PQ) Index To determine ferrous metal fatigue failures and metal-to-metal contact not usually detectable with some spectrographic analysis

PQ Index can detect at an early stage:

  • Anti-friction bearing wear
  • Plain bearing wear
  • Gear wear
Oxidation To determine the level of lubricant oxidation and deterioration

Oxidation can mean:

  • Increased wear and corrosion
  • Shorter equipment life
  • Increased viscosity
  • Excessive deposits and plugging
Remaining Useful Life Evaluation Routine (RULER) - (Linear Sweep Voltametry) To measure individual antioxidant concentration in oil compared to a new oil reference (%) Understanding antioxidant reserve in turbine oils can be helpful in predicting end of oil life and may provide insight on varnish formation
Rotating Pressure Vessel Oxidation Test (RPVOT) To measure the remaining oxidation stability of an oil Oxidation stability is a key performance feature in turbine oils. As an oil oxidizes, the equipment is more prone to build varnish
Ultracentrifuge Rating (UC) To measure varnish deposit formation in oil Elevated deposit formation can signify increased potential for varnish formation
Viscosity To determine the oil’s resistance to flow
  • An increase in viscosity may be due to high soot or insoluble content, water contamination, or admixture with higher viscosity fuel or lubricant
  • A decrease in viscosity may be due to water contamination, or admixture with lower viscosity fuel or lubricant
  • Both high or low viscosity may result in premature equipment wear
Water To detect presence of water contamination Water contamination may cause severe corrosion and subsequent wear, poor oil film thickness or hydrogen embrittlement