Pressure Relief where the vessel has additional vent paths

[dleafe]

Hello,

I have to verify the design of a pressure relief vent (2 x 6" bursting discs in series) for a pressure vessel in which a process upset could see water entering the tank and cause a reaction.

The following sketch shows how the vessel is linked to other vessels by vents and overflows.

There is always a vent path open under normal operation to these other vessels.

My question is, is it allowable to take account of the available vent area in these other routes? The 6" bursting disc route has insufficient area alone for the required relief duty.

I can see no reference in API 521 for such a case.

many thanks

 

[bimr]

Assume worst case. That would be when valves are closed or fluid is trapped. You do not show any valves?

 

[EmmanuelTop]

What is the case here? Are you saying that there are multiple vessels in series which would all contribute to the relief load, whereas the rupture disk is sized for the relief flow from a single vessel?


Dejan IVANOVIC
Process Engineer, MSChE

 

[dleafe]

There are no valves except the Level control valve as shown. The water can only enter D228 so the relief case is based on a reaction in that vessel only. The vent lines connecting the vessels remain clear. The overflows could be part filled with liquid.

 

[Latexman]

When D228 is discharging, is the moisture in the air an issue from a reaction standpoint?

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[dleafe]

The reaction will take place in the vessel. Unless there is two phase flow and unreacted vessel contents are emitted, the moisture in the air should not affect the discharge.