Air Cooler PSV Sizing

[bonkers]

I am sizing a PSV for a natural gas compressor station fin-fan gas cooler. What is the proper sizing design procedure? The customer has requested the fire protection case. Sizing per API 520 requires a seemingly large valve. However, reference material that I have seen tells me that the PSV over pressure protection would most likely not open before the tube heats up and ruptures due to tube metal heating faster than the PSV reaching it's setpoint. How can I install a relief system for this protection condition. There is PSV protection for the compressor and a station emergency shutdown system.

Thank you for your thoughts!
Bonkers

 

[Chance17]

Assuming the fin-fan is 100% vapor, my reference material would not require a safety valve for external fire protection.
If you really have to install a safety valve, I'd use "fire outside of gas filled vessel" based on the tubse plus header volumes.