Gas relief valves for packed H2S Absorber tower

[cubicsupport]

We have two packed H2S absorber towers (5m diameter, 15m tan/tan) in our natural gas treatment units for final polishing to reduce the H2S, which do not have any relief valves. The plant is approximately 20 years old. A recent HAZOP has identified the need for fire relief. We have fail open valves on the tower outlet,to avoid any locked in condition.

As a recent seminar,a similar question was posed for new installation. The indication was that it was "industry practice", not to install PSV on the tower.
Are there any special guidelines for gas adsorber towers?

 

[dcasto]

so, what liquid is in the tower with the gas? or did you mean adsorbers?

Gas filled vessels are stick wickets and you'll find loads of threads here on the subject.

by the time the vessel absorbs(?) enough heat from the fire to heat it up, then a relief valve keeping the pressure at the MAOP, the vessel will eventually fail because the metal will reach the temperature where the lower strenght at high temperature exceeds the stress. With adsorption material inside the vessel taking up some heat, the time to fail will increase significantly.

So, I could support a statement like that especially if the gas had over 500 ppm H2S in it and there was no flare header avaiable.

Overall, I'd buck up and put the $300 valve on it.