Partial stroke testing

Partial stroke test reveals hidden ESD valve failures

Antwerp based leading global synthetics company found that

> Valves that performed spotless in full stroke tests during stops got stuck during live process

> These critical on/off valves would have remained open upon request for an emergency shutdown...

Partial stroke testing

The case > To prevent overpressure in a large, 30 meter high

column, both of its inlet lines are equipped with ESD valves

> The medium going through these valves was a monomer with a temperature of up to 200 °C

Partial stroke testing

What happened? > Valves failed during partial stroke test, despite previous

successful full stroke tests > Valves remained stuck in their seats and could not be

closed during PST test > PST test revealed that the ESD valves could not be

relied upon...

Partial stroke testing

What was the reason? > Process heat caused the ball of the valves to expand

more than specified by the valve supplier > When medium started running through the valves, the

valve could no longer be shut

Partial stroke testing

Ball of the valves replaced as a result of partial stroke test findings

> Balls of the valves were replaced by balls with a suitable expansion coefficient

> More ESD valves equipped with PST systems as a result

> Risks that had come to light were added to equipment malfunction database

> ESD valves are still tested on a bi-weekly schedule

Partial stroke testing

More information > Read the full article > Check out the video on mechanical partial stroke

testing > Find out more about mechanical partial stroke testing

Partial stroke testing