I agree with nasim123
ASME Sec I - Safety valves for power boiler, steam generators, They are required to have 3 % Over pressure(OP) over pop point pressure and 3 % blowdown.
ASME Sec VIII - They can be used as safety (compressible) , relief (incompressible) and safety relief valve.
As per section VIII, OP for safety valve and coded relief valves should be 10%. For non-coded relief valve, OP can be 25 %.
Blowdown should range between 5 and 7 % below pop point.