Rupture risk due to deflagration (low pressure vessel)

[ChemEngSquirrel]

API 521, Section 7.3.2.4 recommends that a minimum design pressure of 3.5 barg be selected for knockout drums in subsonic flares to avoid rupture if a deflagration occurs.

I have a 1.5 barg design P vessel connected to flare. It is a hydrocarbon containing vessel but not the flare drum itself (only vented to flare).

Would the risk of deflagration be considered lower if I routed the vent from the vessel to an atmospheric vent with a flame arrestor? A new vessel is not an option.

Thanks.

 

[sosrotadi]

normally vent stack sizing is smaller than flare stack, there is another risk if a your area is categorized as a lighning area will be another risk if you dispose a combustible gas since it would be uncontrolable
I doubt if deflag occur in internal system,if worried on external fire,around yr KO drum should be equipped by fire water deluge & spray system