Thief Hatch &Vent 1

[egebull]

Can anybody tell me how to check if a vent and thief hatch combined on a 400 bbl atmospheric storage tank will be sufficient to relieve any sudden pressure surges/vapor breakthrough?

Thank you,

 

[Chance17]

In theory the psi to open the thief hatch is [weight of lid (lb)/lid area (in2)].
The hinge offers additional resistance to opening.
The hinge force is hard to predict due to friction & rust.
There are also possible spring forces depending on the model.

Any resulting flow through the device must be reduced by 50% (per OSHA) because it has no vendor calibration.

Using a thief hatch to "officially" protect a tank from overpresssure is highly questionable.
As an engineering professional my recommendation is to put aside this activity.

 

[CMA010]

API STD 2000 / ISO 28300 will give you guidance on calculating required venting requirements.