Method for verifying the operability of a safety valve

A method for verifying the operability of a safety valve, wherein the safety valve comprises a valve member and a positioner for controlling the position of the valve member,

• wherein the safety valve is part of a plant on which a process with a process medium runs,
• wherein the plant comprises at least one sensor for monitoring the state or a property of at least one of the plant, the process, and the process medium,
• wherein the method comprises a first partial stroke test and a second partial stroke test for verifying the operability of the safety valve,
• wherein for the first partial stroke test a first stroke of the valve member is predetermined by the positioner,
• wherein the method comprises the following steps:
• acquiring at least one measured value of the at least one sensor;
• based on the at least one acquired measured value, determining a point in time during the ongoing process at which the second partial stroke test may be performed;
• wherein the second partial stroke test has a second stroke of the valve member by the positioner which is greater than the predetermined first stroke of the first partial stroke test and less than or equal to the stroke in a full stroke test;
• wherein the second stroke is such that the second partial stroke test can disrupt the process to no more than a predetermined extent;
• and
• wherein the second partial stroke test is performed at the predetermined point in time.