A boiler superheater safety valve is set to lift at 450 psi (3102 kPa). Coast Guard Regulations (46 CFR) require that if there is a pressure drop of 10 psi (69 kPa) across the superheater, the drum safety valve should set to lift at a pressure of __________.

Correct Answer: Option C — 465 psi (3206 kPa)

To guarantee adequate superheater cooling, the superheater safety valve must lift before the drum safety valves. Adding the 10 psi superheater pressure drop to the 450 psi superheater valve setting requires the drum safety valve to lift at a minimum of 465 psi.