Devices that are generally necessary on a safety valve
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Safety valves must generally be equipped with the following devices: Lever-type safety valves should have mechanisms to prevent the weight from moving on its own, as well as guides to restrict the lever from extending beyond certain limits. Spring-loaded safety valves should be equipped with a lifting handle and a device to prevent the adjustment screws from being turned casually. Gravity-type safety valves shall be equipped with a device to prevent the weight plate from coming loose. Controlled safety valves must have a reliable power source and electrical supply: (1) The valve in the impulse-type safety valve’s impulse inlet conduit should remain fully open and sealed with lead. (2) Safety valves controlled by compressed gas must have a reliable gas supply and power source. (3) Hydraulic-controlled safety valves must have a reliable hydraulic transmission system and power supply. (4) Electromagnetically controlled safety valves must have a reliable power supply.
A lifting wrench is only installed on a spring-loaded safety valve when required by the operating conditions (such as with steam) or by the customer; it is not mandatory. . .