A pressure actuated and resettable safety valve for controlling the flow through a well conduit which closes in response to an increase in pressure in the well conduit.BALL VALVES Resetting means for opening the valve include a releasable piston for reopening the valve and resetting the valve closing mechanism. Butterfly ValvesThe valve closing mechanism retracting the resetting mechanism for resetting the valve to its initial position for reuse. Generally, it is old to provide a subsurface safety valve for controlling the flow through a well conduit in response to abnormal conditions such as might occur when the well over produces, blows wild or in the event of a failure of well equipment.Safety Valves Prior art subsurface safety valves have in the past been controlled in response to fluid flow through the well conduit, differential pressure across the valve, a decrease in tubing pressure, or by a control line extending to the well surface. The present invention is directed to various improvements in a subsurface safety valve in which the closure is caused to occur by an increase in tubing pressure in the well conduit and in which the safety valve is actuated and reset by application of pressure of a value in excess of shut-in tubing pressure in the conduit above the safety valve without requiring external control lines to the well surface.

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