Shutdown valve

ESD valves are required by law on any equipment placed on an offshore drilling rig to prevent catastrophic events like the BP Horizon explosion in the Gulf of Mexico in 2010.

When an external hydrocarbon, such as methane gas, is present in the atmosphere, it can be sucked into a diesel engine causing overspeed or over revving, potentially leading to a catastrophic failure and explosion.

When actuated, ESD valves stop the flow of air and prevent these failures.

Typical examples of these are: In addition to the fluid type, actuators also vary in the manner in which the energy is stored to operate the valve on demand as follows: The type of actuation required depends upon the application, site facilities and also the physical space available although the majority of actuators used for shutdown valves are of the spring return type due to the fail safe nature of spring return systems.

For this to operate, fuel, air and steam pressure can be converted to electrical signals by means of bellows, a bourdon tube, or a diaphragm-operated mercury switch.

Among the others 2 types of testing methods are: The performance standard of ESDVs may include the specification and testing of a closure time (e.g. to close in less than 10 seconds) and the specification and measurement of an acceptable leakage rate of fluid through the closed valve.

Pneumatically actuated shut down valve
A diagram of the internal components of a safety shutoff valve. When this type of valve is tripped, the flow is quickly stopped and an indicator disc tells the operator that the electrical circuit has been opened by a failure somewhere in the system. When the system failure has been corrected so that the circuit is again closed, the valve can be opened by the action of the hand lever . If, however, the system failure has not been satisfactorily corrected, the circuit will remain open and moving the hand lever will not open the valve, because the valve stem remains disengaged from the handle.