Atmospheric storage vessels' pressure / vac rating

[engineermum]

I am a UK engineer, looking at "fitness for purpose" calculations for atmospheric (low pressure) storage vessels. These are often vertical cylinders with dished ends, and therefore do not fit the atmospheric tank codes.

My colleague who is carrying out relief calculations for similar tanks has asked what the pressure / vacuum relief rating for these tanks usually is. We agreed that +56mbar / -6mbar was typical.

Where do these "typical" figures come from? API620, API650 and EN14015 all refer to 100mbar.

 

[JStephen]

Right offhand, I'm not aware of any place where API 620 or API 650 refer to 100 mbar, can't say for EN14015. For API-650 and API-620, the allowable pressure and vacuum would vary depending on the design and construction details, and is not a single number for all tanks built to that standard.

Vertical cylinders with dished ends may fit API-650, API-620, or ASME B&PV Code, depending on the details. That doesn't imply that the tanks in question were designed per any of those standards.