Safety Relief requirements, external fire

[Diborane]

I recently completed sizing the SRV flow requirements for an ASME stamped vessel. One of the cases that I checked was for external fire causing the vaporization of the contents according to API 521 3.15.

My work was then sent for review to a senior engineer. He stated that I did not need to size an SRV on the reactor for the fire case.

The SRV size needed for the fire case is larger than any of the other cases looked at.

Isn't sizing for an external fire required for all ASME stamped pressure vessels? If not what cases allow you to not to have this protection? Does it matter if there aren't any likely scenarios where flammable materials would be near the vessel?

 

[moltenmetal]

If there is no credible scenario for a pool fire around the equipment in question, it's my understanding that you do not need to size relief for fire. This of course means no storage of combustible liquids etc. anywhere near the equipment in question, non-combustible construction of surrounding structures, fire suppression equipment (sprinklers etc.) and adequate access to firefighting. This means consideration of not just your equipment, but the equipment in the surrounding plant.

But what happens if someone later installs flammables storage which introduces a credible fire risk for your equipment? That becomes a management of change issue for the new installation.

If the reactor itself contains flammable or combustible liquids, you MUST design for fire because the equipment itself could be the source of the pool fire.

 

[Diborane]

Thank you moltenmetal. The final decision is not mine I just wanted to learn more for the future.