Partial Stroke Testing Device Avoids Costly Downtime

Dutch process-interlocking and valve-control specialist Netherlocks has developed a method of testing emergency shutdown (ESD) and high-integrity pressure-protection system (HIPPS) valves during normal operation of a plant, avoiding the loss in productivity caused by conventional testing methods.

Netherlocks FAITH testing system for ESD & HIPPS

The Fail Action Integrity Test Handling (FAITH) system limits the stroke of the valve-actuator combination to just 20 degrees, enough to guarantee the reliability of the valve without impacting on production.

Valves used in ESD and HIPPS fail-safe procedures which have not been operated for a long period of time risk becoming immovable due to the actuator and valve seals becoming stuck together.  Should an emergency shutdown become necessary and one of the valves will not close, an extremely dangerous situation could arise.

The conventional manner of testing these valves involves closing them completely, which leads to costly downtime, and this is only carried out during a complete plant shutdown.  Since complete shutdowns are very rare events, plants tend to install an expensive, over-sized actuator to ‘crack’ the sticking valve.

The FAITH system removes the need for such an actuator while enabling tests to be performed more frequently and conveniently.  It replaces the standard bracket and coupling between the actuator and valve, and will only allow the valve to be partially operated once the correct linear key has been inserted.

The FAITH device works on a completely mechanical principle, obviating the need for wiring, software or a PLC.  Maintenance-free and fail-safe, it can be used with both linear and rotary actuators.

Netherlocks’ complete product range can be found in a newly-released brochure.  This document features the company’s four main product groups: process interlocking, valve control, lock out / tag out and machine guarding.  A copy can be requested by visiting

Comments Off on Partial Stroke Testing Device Avoids Costly Downtime