터빈 액추에이터 오일 계통에서의 윤활유 열화 및 부식 메커니즘

Hydraulic actuators in gas turbine (GT) inlet guide vane (IGV) systems are crucial for the stable operation of combined heat and power (CHP) plants. This study systematically investigates the internal damage and corrosion behavior of a GT IGV hydraulic actuator recovered after long-term service in a district heating CHP plant. The manifold block, cylinder tube, and piston were disassembled and analyzed to assess the effects of lubricant degradation and water contamination. Visual and cross-sectional examinations revealed localized corrosion pits, oxide accumulation, and uneven material thinning on lubricant-contacting sur- faces, with maximum pit depths measuring 0.18 mm in the manifold block, 0.13 mm in the cylinder tube, and 0.07 mm in the piston. The chromium plating, approximately 18 μm thick, effectively suppressed deg- radation of the cylinder tube; however, localized coating damage led to interfacial corrosion and acceler- ated substrate degradation. Lubricant analysis showed fluctuations in water content, particle contamination, and PQ index, indicating a lubricant environment susceptible to hydrolysis, additive depletion, and tribo- corrosion. These findings demonstrate that monitoring lubricant properties alone is insufficient to accu- rately represent the evolution of internal damage and provide direct experimental evidence linking lubricant degradation and water contamination to the internal corrosion of hydraulic actuators.