Shutdown Valve (SDV) are used for isolation of process system in case of emergency.

i) Should a preventive measure (PM) apply on SDV ?

ii) When or what conditions shall we implement preventive maintenance (PM) to shutdown valves ?

ii) Any specific reference or standard governing PM ?

Is it a control valve (hydraulic, pneumatic, electric), or  a simple hand/motor operated gate valve?

In case of a not human-powered valve there will be some PM, even if this is walking around every month for a visual check.

Even and-operated valves, need some grease or oil, check if there are no packing leaks, and in all cases, check the function of the valve (isolating).

A missing handwheel can be a matter of life and dead, if dealing with steam.

A pneumatical operated ball valve will have a risk of 'stickin' increasing torque necessary to loosen and move the ball. The seats may be damaged, the actuator may develop a leak (if not spring return operated) the solenoid valve for the actuator may be the weakest part if not especially selected for high quality or in redundance combination.

Dependability is of course given as a combination of quality and dimensioning (oversizing, mechanical safety factors) of the equipment.

Tests should be done for this whole ESD combination at a weighing between 'worst case scenario consequences' if failing and cost of test, if the test sequence is not given in any other way.

Sequence: testing at each startup, not less than once a month for good safety measure, at least not less than each quarter.

2011-01-18

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