Storage Vessel Depressurization

[AggieCHEN04]

Are there any API guidelines for the blow-down of pressure vessels to flare? Are there any guidelines for how quickly the blow-down should occur (such as, no greater than 20 psid/minute or 10%/minute)

 

[garfio]

Take a look to API RP 521. It has some general guidelines but not like those you are looking for.

 

[AggieCHEN04]

Yep. So far all we have to go by is the size of the flare system that these vessels are feeding into.

 

[thvo]

In the Danish Offshore Sector the rule is, that the pressure must be decreased to the lowest of 7 barg or 50% design pressure within 15 minutes.

The acceptable flow rates are thus governed by your flare system capacity. It is common practice to built-in delays for some of the depressurisation valves in order to average the flare load in the 15 minutes and reduce the peak load.