If I were to do 20 PSM/RMP audits per year with new clients, I estimate that I would have the following debate 15 times! In my Process Safety courses, I have a little fun with the phrase “Upwards and Unobstructed” as I make the class stand and repeat that phrase three times. But somehow/somewhere, this basic design characteristic got lost in many Pressure Relief System design basis.
I will cite either ASME Section VIII or ASME B31.3, Chapter II Design which states:
(emphasis by me)
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322.6.2 Pressure Relief Discharge Piping Discharge lines from pressure-relieving safety devices shall be designed to facilitate drainage. When discharging directly to the atmosphere, discharge shall not impinge on other piping or equipment and shall be directed away from platforms and other areas used by personnel. |
Why would ASME require vents off of PRDs to facilitate drainage if they allowed 180-degree goose necks to be part of a PRD design basis?