Patent ID: 8474538
Filing Date: 2013-07-02
Classification: E21B,Y10T

Abstract:
1. A riser tension ring assembly, comprising: a tubular body; hydraulic fluid passages formed radially through the body, each of the passages intersecting an outer circumference portion of the body; a plurality of dogs, each of the dogs being carried within one of the passages, the dogs being selectively moveable within the passages between extend and retract positions in response to hydraulic fluid pressure applied to the passages; a lock ring circumscribing the outer circumference portion of the body and selectively rotatable from a non-locking position to a locking position; openings formed in the lock ring that register with the passages when the lock ring is in the non-locking position to enable a back of each of the dogs to move into one of the openings while in the retract position, the openings being angularly offset from the passages when the lock ring is in the locking position thereby forming a backstop for the dogs to prevent the dogs from retracting while the lock ring is in the locking position; and wherein the lock ring is rotatable from the non-locking to the locking position only when the dogs are in the extend position.