| 摘要 |
<p>The invention relates to an improved subterranean well safety valve wherein an annular actuator is moved downwardly by applied fluid pressure to effect the opening movement of a valve head of a valve relative to an annular valve seat. The initial downward movement of the actuator effects the displacement of a valve stem which extends through a restricted aperture in the valve head, moving a ball valve segment on the valve stem from a seat in the aperture, thus permitting the bleeding of any fluid pressure differential existing on the lower side of the valve head relative to the upper side and reducing the amount of force required to move the valve to its open position. Additionally, in one embodiment, a locking sleeve is slidably mounted within the shiftable annular actuator and such sleeve is operable by an auxiliary tool to effect the radial shifting of locking elements carried by the actuator into locking engagement with the valve housing to achieve a temporary locking of the valve in an open position. The travel of the locking sleeve relative to the valve housing in a reverse direction is limited by a shearable pin so that reverse forcible movement of the locking sleeve will shear the pin and effect a permanent locking of the radially expansible locking segments carried by the actuating sleeve to the valve housing, thus permanently locking the valve in an open position.</p> |
