Repeated failure of Moog servo control valves caused poor reliability and availability in a GE Frame 6FA gas turbine.
Servo-valve failure was common occurrence from early on in the life of the plant which was running on the initial fill of lubricant. This caused an unacceptable level of unplanned outages. Less than three years after commissioning, the situation was unmanageable. The high incidence of servo-valve malfunction had a negative impact on reliability and availability of the plant. Oil analysis confirmed evidence of increasing degradation of the lubricant.
Since installing Castrol Perfecto XPG, there have been no recorded servo-valve malfunction trips in over seven years of operation.
Immediately on changing to Castrol Perfecto XPG servo-valve malfunction and failures due to deposits and varnish from lubricating oil were eliminated. At the same time, a dramatic reduction in the levels of total insolubles was observed in the oil as a result of the product’s extremely low sludge-forming and varnishing propensity.
Since filling with Castrol Perfecto XPG no supplementary cleaning systems have been used, and planned replacement of servo valves is limited to a three year interval at major outages. There has been no partial oil change, additive treatment or any other action.
Over seven years of reliable service has been recorded on a single charge of Castrol Perfecto XPG without a single servo-valve problem attributable to varnishing from the lubricating oil.