Coast Guard Regulations (46 CFR) concerning superheater safety valves require that the valve __________.

Correct Answer: Option C — nominal size is not less than 1.5 inches nor more than 4 inches

Title 46 CFR governs marine boiler safety appurtenances, explicitly requiring that the nominal inlet size of superheater safety valves must fall within the range of not less than 1.5 inches and not more than 4 inches to ensure reliable overpressure protection.