The Crosby BlockBodyTM Safety Relief Valve has been specifically designed to meet high-pressure safety relief requirements using only one valve, rather than a series of valves, in applications involving very high set and back pressures, outside the range covered by industry standards such as API-RP-526. Traditionally, a series of smaller safety relief valves operating in parallel has been used to meet the pressure rating not normally obtainable on larger orifice items. The guiding principle with such an arrangement is that the sum of the orifice areas of all the valves should be sufficiently large to discharge the total capacity of the system. However, this parallel concept has significant drawbacks in terms of greater weight and required space, increased maintenance and the creation of a greater number of potential leakage paths. The unique feature of the Crosby BlockBody Safety Relief Valve – its ability to withstand higher pressures – derives from the use of a superstructure envelope manufactured from a solid forging, giving it far greater structural integrity than the conventional cast body and bonnet assembly. Strength is further enhanced by the replacement of bolt-through flange connections by studding locations machined directly onto the inlet and outlet flange faces.
