Samson Aktiengesellschaft

Focus-on V.o.f.

David Wagner-stürz

Adriaan Hendrik Boer

Kavreet Bhangu

Nadine Wetzstein

Methods for testing the operability of a safety valve, as well as a solenoid valve for triggering a safety valve, and corresponding devices are proposed. The safety valve has a solenoid valve which is used to vent the pneumatic actuator in a safety case. Initially, a safety case is triggered. The position course of the valve member is recorded, and the time required until the safety position is reached is compared with a reference value. From this, it can be reliably concluded whether the assumption of the fail-safe position was caused by the solenoid valve or by the positioner. The measured values of pressure sensors can also be taken into account and allow further diagnostics to be carried out if operability is not assured. If the result of the test is positive, maintenance intervals can be optimized.

Testing the operability of a safety valve for a safety case

The invention relates to a method for detecting a spring breakage in a preloaded drive of a control valve. The method is based on the fact that the pressure which must be applied to achieve a certain valve member position falls significantly after the breakage or failure of the spring. The breakage of a spring in a preloaded drive can thus be detected reliably using the sensor system already present in the control valve, moreover without having to disrupt or interrupt operation.

Spring fracture detection in a preloaded actuator of a control valve

A method is proposed for establishing termination criteria for a partial stroke test on a safety valve, including: a) A partial stroke test is carried out when the safety valve is operational. b) Position of the valve member and pressure in the drive fluid are recorded. c) A first relation is derived, which relates position of the valve member, time, pressure of the drive fluid, and/or control deviation to one another. d) This relation is defined as a safety valve reference curve. e) A second relation is defined, which has a predetermined distance from the reference curve. f) Termination criterion include: If the partial stroke test is repeated on the same valve, the same data are recorded and a third relation is derived for the reference curve, the partial stroke test is not passed if the third relation has a greater distance to the reference curve than the second relation.

Establishing termination criteria for a partial-stroke test of a fluid driven safety valve, and determining the proper functioning of a fluid driven safety valve

The disclosure provides a method for testing a solenoid valve for triggering a safety valve having a single-acting fluidic drive and a positioner. The drive fluid pressure is increased by a first pressure difference. An attempt is made to switch the solenoid valve to the safety position. The drive fluid pressure is measured at a specified point in time that is selected such that the pressure in the drive fluid lowers at most by the first pressure difference. If the pressure in the drive fluid is higher than a reference pressure at the specified point in time, the functionality test of the solenoid valve is failed. The lowering of the pressure in the drive fluid is monitored over a defined period of time to make conclusions regarding the pressure generating system. The pressure does not fall below the operating pressure so the position of the valve member remains constant.

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Mühltal, Germany

David Wagner-stürz