In an industrial setting such as a chemical plant, oil refinery or a deep-sea oil rig, there are safety instrumented systems in place that are designed to promptly bring about a safe shutdown of a process if certain hazardous conditions are detected. Such safe shutdowns frequently involve isolating a process fluid flow, often accomplished using an ESD (emergency shutdown) valve. If the ESD fails dangerously, when a hazardous condition necessitating a shutdown occurs and the ESD does not perform its function when required, the worst-case consequences can be catastrophic.
ESD valves often include a solenoid valve in the ESD design with the solenoid valve energized in an open position while the process operates normally and with the solenoid valve moving to the closed position to initiate a safe shutdown of process fluid flow. Solenoid valves can fail (be unable to close on command) due to several different conditions. However, the failure mode contributing most significantly to the dangerous failure rate of the solenoid valve is that of sticking or adhesion.