Glossary · Functional safety
Emergency shutdown valve (ESDV)
Also known as: ESDV, ESD valve, shutdown valve
German: Notabschaltventil
In the process industry, an emergency shutdown valve (ESDV) is an automated on/off valve that moves to its safe position, usually closed, on a demand from the emergency shutdown or safety instrumented system in order to isolate or depressurize part of the plant.
- Functional safety
- Integrated systems
In one sentence
An emergency shutdown valve (ESDV) is an automated valve that moves to its safe position on demand from the shutdown system.
Example
When gas is detected at a wellhead, the SIS de-energizes the solenoid of the ESDV on the export line, and the spring-return actuator closes the valve within the specified time.
How it applies
- Engineering: ESDVs are typically designed fail-safe, for example with a spring-return actuator that closes the valve on loss of air or power. Closing time, leakage class and fire resistance are specified per application.
- Functional safety: As a Final element, the ESDV is often the least reliable part of a SIF. Its failure data, diagnostics and test strategy strongly influence SIL verification.
- Maintenance: Proof tests include a full stroke and may be supplemented by partial stroke testing during operation. Partial stroke tests reveal only some failure modes and do not replace full proof tests unless the analysis allows it.
- Documentation: Record the safe position, closing time, test method and interval for each valve tag. The documentation team should describe manual reset and reopening procedures clearly, because reopening an ESDV can itself create a hazard.
ESDV vs. control valve
A control valve modulates flow during normal operation. An ESDV stays fully open during normal operation and only acts on demand. Using a control valve as a shutdown valve is possible but must be justified with respect to independence and common-cause failure.