Regarding process safety and risk mitigation during plant’s operational upsets, traditional methods and new techniques/best practices not only guide us to risk free working environment, but also open new horizons to mitigate any catastrophic incidents, which may not happened yet.

For pressurize systems, relief devices are being used to ensure safety of surroundings. Essentialities of pressure relief valves (PSV/PRV/PZV) are proved to prevent any over pressure scenarios in the fluid flow lines or equipment systems. Commonly, these situations may be the resultant of any unwanted flow line blockage, or exposure of system to external flames or thermal expansion or any other unwanted cause to increase pressure inside the system. Selection of proper PSV as per requirement is the key factor and depends on governing relief scenario, back pressure, set pressure and fluid properties. Relief load calculations must be performed very carefully along with optimizing the flare system.

Case study focused is of; “De-Butanizer and De-Iso-Hexanizer of LPG Plant’s strippers (relief load calculations in case of Site wide Power Failure)” highlights the one of very inimitable scenario and its required calculations for selection criteria of proper PSV. This area is addressed very first time from safety point of view, and case study shows a much unexpected settings which comes up with grim potential of failure.

Purpose of the case study is to highlight this scenario as such an oblivious area which can become a dramatically staid failure of the system at any time. This case study should be the guideline for every process engineer to mitigate such scarce cases to save any potential catastrophic incident.