An Antwerp based leading global synthetics company uses partial stroke testing to test the availability of some of their most critical ESD valves. Remarkably, they found that some valves that performed spotless in full stroke tests during stops, turned out to be stuck during live process. Without mechanical partial stroke tests, these critical on/off valves would have remained open upon request for an emergency shutdown.

1. Partial stroke testing
Partial stroke test reveals hidden ESD valve failures

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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