PG−72.1 Safety valves shall be designed and constructed to
operate without chattering and to attain full lift at a pressure no
greater than 3% above their set pressure. After blowing down,
all valves set at pressures of 375 psi or greater shall close at a
pressure not lower than 96% of their set pressure, except that all
drum valves installed on a single boiler may be set to reseat at
a pressure not lower than 96% of the set pressure of the lowest
set drum valve. All valves set at pressures below 375 psi shall
have a blowdown not greater than that specified in the following