A Case Study in Steam Turbine Valve Lubrication Reliability
Steam turbine governor control valves operate under demanding thermal conditions that challenge lubricant stability. In a case study involving a U.S. electricity generator, Miller-Stephenson reported that changing the grease helped address drying-related failures and avoid recurring maintenance shutdowns.
Steam turbine governor control valves play an important role in regulating equipment operation. Their moving components require suitable lubrication to maintain reliable movement. At high temperatures, grease may dry out or lose effective lubricating performance, potentially increasing wear, sticking and maintenance requirements. Lubricant thermal stability must therefore be considered alongside actual operating conditions.
Miller-Stephenson’s Krytox XHT-BDZ case study describes a U.S. electricity generator experiencing problems with steam turbine governor control valves. The valve arrangement placed the components closer to the turbine than usual, exposing them to higher temperatures. The existing grease dried out, requiring at least four shutdowns per year for maintenance and bearing re-sleeving. The company reported that the base-load unit supplied more than 500 MW to the electricity grid.
According to the case study, switching to Krytox XHT-BDZ grease allowed the lubricant to withstand the application’s high temperatures. The camshaft bearings and fulcrum pins remained lubricated, and the recurring shutdowns for this maintenance issue were avoided.
The case highlights the importance of evaluating operating temperature, component design, speed, load and maintenance requirements when selecting lubrication for high-temperature equipment. Before changing lubricants, engineers should verify technical data, material compatibility, application methods and relubrication needs. This is a specific reported application, not a guarantee of identical results in every steam turbine valve.
