Abstract: A connector for securing a first cylindrical member to a second cylindrical member comprises a cylindrical body which includes a first end that is attached to the first member and a second end that is positioned proximate the second member, a cylindrical housing sleeve which is positioned concentrically over the body and which includes an upper end portion that is secured to the body and a lower end portion that is disposed adjacent the second member, a cylindrical primary piston that is positioned between the body and the housing sleeve, a locking mandrel which is connected to or formed integrally with the primary piston and which includes at least first and second annular portions that have different diameters, and a split lock ring which is supported by the lower end portion adjacent a number of locking grooves in the second member and which includes at least first and second cylindrical portions that correspond to the first and second annular portions of the locking mandrel.

Abstract: A connector for securing a first cylindrical member to a second cylindrical member comprises a cylindrical body which includes a first end that is attached to the first member and a second end that is positioned proximate the second member, a cylindrical housing sleeve which is positioned concentrically over the body and which includes an upper end portion that is secured to the body and a lower end portion that is disposed adjacent the second member, a cylindrical primary piston that is positioned between the body and the housing sleeve, a locking mandrel which is connected to or formed integrally with the primary piston and which includes at least first and second annular portions that have different diameters, and a split lock ring which is supported by the lower end portion adjacent a number of locking grooves in the second member and which includes at least first and second cylindrical portions that correspond to the first and second annular portions of the locking mandrel.

Abstract: A subsea wellhead tieback connector operatively used to connect to a marine riser pipe or a well conductor in a manner that that will not unthread or unloosen the joints of the riser pipe being unlocked. The tieback connector operates with a novel internal latching mechanism having a hydraulic piston, an inner body that stretches and deflects in a unique manner resulting in compression spring forces at two locations, an expanding lock ring, a threaded adjustment ring, and a reaction ring. During operation the tieback connector creates an enhanced mechanical advantage to originate a required pre-load force without the necessity of having to generate a large hydraulic force that would otherwise be needed.