Answer / haridass

In normal running plant the ESDVs will not be operated
unless there is an emergency situation, it happens rarely.
Sometime those valves will get struck in open position and
it will not help the situation to protect the plant.

So to avoid this kind of problem, the PARTIAL STROKE
TESTING (PST) system is applied. Periodically, the ESDV
will be closed 20% from full open to close and immediately
open fully, which will not affect the process flow. This
movement makes the valve free from struck-up.

This PST function takes place only when the valve is full
open. During the valve close PST FAIL alarm will be
occured. and recorded in the event summary.

Answer / yasir & farhan

we give nearst 70 psi so just we that esdis fully open or
close

Answer / kyle condran

So you know your actuator works without fully closing you esd valve, as this is not a good idea unless you want to upset your process.

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