Our 475# steam goes from an unfired boiler to a superheater. Both the boiler and the superheater are not registered as ASME Sec. 1 Boiler Code. The PSV on the boiler itself is able to relieve the full amount of steam generated at relieving conditions (which is less than at normal conditions).

How do I size the PSV on the superheater? The superheater is a fired heater/furnace, but not registered as ASME Sec. 1, so ASME Sec. 1 is not applicable. So...do I just use the heat duty of the superheater? This would result in a pretty big PSV.

Thank you in advance for all your help.