91. The MAWP of a boiler is 900 psi and the normal drop across the superheater is 20 psi. If the superheater safety valve is set to lift at 825 psi, the minimum settings of the drum safety valves allowed by Coast Guard Regulations would be _______.

The drum safety valve setting must be at least the superheater safety valve setting plus the normal pressure drop across the superheater. With a superheater safety valve setting of 825 psi and a 20 psi pressure drop, the minimum drum safety valve setting is 845 psi, requiring a setting of 850 psi to satisfy regulations.