Series Figure 31 Steam Safety Relief Valves are ASME section I valves used on steam boilers with operating pressures from 5 to 250psi (.34 to 17.2 bar). Series Figure 31 is a high capacity safety relief valve with a top guide and full nozzle. It consists of a bronze body (sizes 1/2 to 2 1/2 in.) with NPT threaded male inlet and threaded female outlet (drain) connections, or a cast iron body (sizes 1 1/2 to 6 in.) construction with flanged connections. ASME, Section I rated.