Subsurface well safety valve and control system

摘要

Subsurface safety valve assembly (16) for oil wells comprising a valve element (57) and a temperature responsive operator comprising multiple coil springs (69, 70), made of shape memory material, operable in opposing directions for opening and closing the valve element and a ratchet locking mechanism comprising wickers (79) for locking the valve in its open position after removal of the heating which causes shape memory effect movement to such position.