On-line valve monitoring and diagnosis

A valve monitoring system that enables the selection of power plant steam and containment valves to be serviced to be made on a justifiable priority-of-need basis is described. The system is designed to assist utilities in increasing plant availability and in decreasing maintenance costs attributed to valving. The system operates in one of two modes: trending or single-stroke. In the trending mode, the system monitors the performance of critical valves while the plant is online and compares sensor data with baseline signatures. Deviations from baseline data are evaluated by an expert system, and when the deviations exceed caution levels, probable causes of trouble are identified. In the single-stroke mode, the system is hooked up to any valve when the plant is offline and the valve is cycled through one full stroke (opening and closing). Using engineering data for the valve, the sensor signals are analyzed and a diagnosis is made.<>