Petroleos Mexicanos (PEMEX) has chosen Netherlocks B.V. to supply its FAITH partial stroke testing systems for three offshore facilities in the Gulf of Mexico. The FAITH tests ESD (emergency shut-down) valves with a partial stroke operation, therefore not interrupting production during the test. Partial stroke testing is of major importance to end users, as an important safety step to ensure that an ESD valve will operate as intended, when needed. All valves can become worn or stuck over time, so something as vital as an ESD must be tested frequently in order to meet SIL standards. A partial stroke test enables testing without halting process flow, meaning tests can be carried out more easily and more often, which should then also create a more reliable ESD system. The mechanical nature of the FAITH system ensures that the specified degree of opening (test angle) is not exceeded during the test. The Netherlocks device can also be used to block the actuator to perform maintenance on the ESD during production. Instead of relying on a potentially complex electronic system for a simple – but vital – operation, the FAITH is itself a simple, maintenance-free mechanical device that can still offer electronic feedback with optional added components.