(52c) Enhance and Ensure the Probability of Failure Demand of Multiple Relief Devices by Different Approaches and Design Tools

The process safety last active layer of protection are relief devices or blowdown system.
The system is design to handle the excess system pressure & load due to number of
contingencies and problems. The ineffective and improper old relief valves shall
decrease the probability and may put the system on risk, if the cumulative Probability
of Failure Demand (PFD) lower than the actual creditability.

For the evaluation of actual credibility of multiple relief device PFD, there are several
tools used to evaluate the offline performance of those safety equipments and these
evaluations modes variate with respect of type of device. The One of them tools are
PSV inspection through beach test at require/evaluated frequency. Any failure happen
for single relief device during bench test shall suspect the credibility of other multiple
device and may chance to reduce the PFD of cumulative multiple device.

Each set of multiple relief valves considered periodic inspection and evaluate the
performance with respect of result. The study were done by using different approaches,
tools and utilize number of international applicable standards. There were three
different approached (CCSP, API/ASME and Real time dynamic simulation) used to
evaluate the satisfaction of multiple relief performance.

The definite cost for such enhancement is set the complex under safe envelope and
remove the risk on equipment/units/complex. This approached & philosophy not only
limited to safe the cost of frequent replacement of relief devices or additional, but also
avoid the force shutdowns. The impact of study and change methodology had
removed the failure and provided the confidence to complex.