Designer steam boiler should consider the size, relieving or discharge capacity, set pressure and number of safety valve. These parameters depend on the presence of valve between steam boiler and safety valve in superheater and the pressure drop upstream of safety valve.
Installation of safety valve in reheater must be applied minimum one safety valve. Determining discharge or relieving capacity of safety valve in reheater is different with safety valve in boiler. It must be calculated separately. Safety valve in reheater can be located between reheater outlet and the first main stop valve.
If the temperature of steam flow exceeds 450 F, the safety valve should be equipped with casing with a spindle, bonnet, body and the base. These materials are fabricated from alloy steel or steel, or other material which has high heat resistance. The connection of safety valve can be flanges to make easy for maintenance or welded connection.
|Figure 1: Safety Valve in Superheater|