What Routine EHC Fluid Analysis Fails to Detect: Improved Phosphate Ester Maintenance Through Non-Routine Testing
Matthew G. Hobbs, PhD, Peter T. Dufresne Jr.
Despite the critical nature of electrohydraulic control (EHC) systems, many steam turbine operators’ oil analysis programs fail to detect fine insoluble contaminants that are responsible for costly downtime and failures. With minor modifications, however, gas turbine oil tests can be made suitable for use in steam turbine EHC applications. A modified version of the industry-standard membrane patch colorimetry (MPC) test, in particular, allows for the identification of “hidden” contaminants that are often responsible for costly EHC failures. By exploiting MPC analysis to its full potential, this method can be used to qualify application-specific problems like varnishing and dieseling in addition to quantifying their severity. Once these previously “hidden” problems have been identified, effective EHC fluid maintenance practices can be developed so that steam turbine performance and reliability may be ensured.