Actuated (MOV) Valves

The most common requirement for key interlocking of power-actuated valves occurs in Pig Launcher/Receiver systems, Scraper Traps and Sand Filter systems etc, where power actuated valves need to be interlocked with manually-operated valves and vessel closures. Due to the ultra-critical nature of such valves, special considerations may arise:

  1. Where valves are part of an ESD system, the key interlock system must not compromise the valve’s fail-safe function.
  2. Where pigging operations occur, the key interlock system must verify the valve’s absolute position (open and/or closed) independent of any on-board instrument indication.
  3. On electrical actuators, where the key interlock system de-energizes the valve, any anti-condensation heating circuitry etc. must remain uninterrupted.
  4. Where actuators are equipped with a manual override facility, the key interlock system must permit operation of the valve in both modes (or in a combination of both modes – e.g. in the event of a power failure) while maintaining the integrity of the key sequence at all times.

These same key sequencing principles can be applied effectively to the management of motorized gate valves.