Patent ID: 7628176

Claim:
A mechanism for temporarily blocking flow in a pipeline having a flow axis, comprising a split housing for welding around the pipeline and having a device for positioning a valve on top of the split housing whereby a cutter and then a pipeline stop may be inserted into the split housing; an actuator for mounting on the valve to operate a pipeline stop providing a linearly movable output incapable of transmitting torque; and a pipeline stop including a central section cooperating with the output and having a series of downwardly facing recesses; a pair of lateral sections each having an outer face for sealing against flow through ends of the pipeline extending into the split housing and an inner face having a series of upwardly facing recesses; and a series of inclined links having ends movably abutting the upwardly and downwardly facing recesses and capable of angular movement relative thereto, the links being downwardly inclined from the central section toward the lateral sections so that downward movement of the output causes downward movement of the central section toward a lower position thereby moving the links from a first position defining a first angle to a longitudinal axis of the pipeline to a second position more nearly aligned with the pipeline axis and causing outward movement of the lateral sections for stopping flow through the pipeline and upward movement of the central section away from the lower position allows inward movement of the lateral sections so the pipeline stop can be removed from the pipeline whereby moving the links toward the second position creates an increasingly large force sealing the outer face against the pipeline ends.