(121c) Improving Reliability & Safety Performance of Solenoid Valves by Stroke Testing

Solenoid valves integrated into the design of emergency shutdown valves (EDS) used in industrial process systems can tend to bind, i.e., to become stuck in one position, when not moved for long periods of time. This binding, also known as failure due to excessive stiction, has significant negative impacts on the valve’s reliability and safety performance. It is a serious and costly problem normally addressed by expensive and time-consuming proof tests which typically have required a process shutdown to perform testing. This paper describes an effective, alternative in-service testing prptocol, known as valve stroke testing, which verifies whether or not the solenoid valve is stuck in position. It recommends a best practice procedure for implementing the valve stroke test and provides a quantitative example of how valve stroke testing significantly improve safety performance.