Refinery Vessel PSV Requirements
Refinery Vessel PSV Requirements
(OP)
During a prior HaZop of a refinery process unit (a H2SO4 Alky), it was stated (I assume by the facillitator) that even though the PSV on the isobutane surge drum was adequately sized for the controlling fire case, API codes now required dual PSVs, so a second PSV should be added. I can't find anything or anyone to confirm this statement about dual PSVs is true. Does anyone know of a recent change to the API RPs on PSVs for ASME VIII vessels? This is not a ASME I boiler vessel.





RE: Refinery Vessel PSV Requirements
RE: Refinery Vessel PSV Requirements
Not having a spare PSV means there's a risk of having to shutdown the process to fix the PSV.
RE: Refinery Vessel PSV Requirements
RE: Refinery Vessel PSV Requirements
- HazOp - Hazardous Operations Study -
- LOPA - Level of Protection Analysis -
prognosis: Lead or Lag
RE: Refinery Vessel PSV Requirements
RE: Refinery Vessel PSV Requirements
OSHA doesn't mandate HAZOP. HAZOP is fine, but there are other alternatives too, such as LOPA. OSHA 1910.119 mentions HAZOP and then goes on to say that equivalent alternate methodologies are also acceptable. LOPA is one of those equivalent alternatives.
RE: Refinery Vessel PSV Requirements
- If the vessels is operating 24/7
- If the vessel is connected to a common flare header
Best regards
Morten
RE: Refinery Vessel PSV Requirements
The provision of dual PSVs on vessels depends on company operation team. On the project we completed recently, based on HAZOP recommendation with input from the company's operation team, they requested us to replaced all single PSV with dual PSVs.
My past shall not limit my future....
RE: Refinery Vessel PSV Requirements
typically a HAZOP would list situations such as "NO FLOW" and then list the causes of No Flow (e.g., closed outlet valve) and then discuss the consequences of No Flow (e.g., pressure accumulation, high level, etc.) and then list safeguards (e.g., high pressure alarm, high level alarm, PSV, etc.). and finally would ask if the safeguards are adequate.
If the additional PSV was under a "High Level" situation then i would be asking if the PSV is large enough for liquid relief instead of vapor.
i think the rationale of the facilator might be hiding in the "challenge" of where it the action item was listed.
RE: Refinery Vessel PSV Requirements
My past shall not limit my future....
RE: Refinery Vessel PSV Requirements
I'm simply not familiar with any such requirement.