Abstract: Special J-slot connectors have been devised for connecting concentric riser pipes and casing from a structure at the surface of a body of water to corresponding concentric casings set in the sea floor. This can be called a "tieback tool" for sealingly securing a first tubular member suspended from a vessel floating on a body of water to a casing hung in the wellbore in the bottom of the body of water. Special multiple axially aligned J-slot means are also provided together with means to assure proper "makeup" of the J-slots. Means are also provided for proper alignment of circumferentially spaced J-slot connectors. Special self-emergizing seals are also disclosed.

Abstract: A threaded connector for a pipe string, such as a production riser used in connection with sub-aqueous wells, in which the threaded connection between the pin member and box member of the connector is made up initially through an application of relatively low torque to the members, after which the connector has a straight line pretension force of a high tensile value applied to it through use of a suitable tool, the high pretension force being retained between the mating threads of the pin and box members by a preload reaction member threaded on the pin member and rotated into solid engagement with the box member while the pretension force is being applied, to lock the preload in the connector between the threads.

Abstract: Pipe connectors particularly useful in securing sections of an underwater marine riser together, including a pin received in a box which are secured to one another by a plurality of lock dogs mounted in the box and movable radially inwardly against a portion of the pin by fluid actuated pistons to force the pin and box firmly together, the dogs being retained in position by fluid operated lock pistons. The lock pistons are operated by fluid pressure to shift them to an unlocking position, the fluid actuated pistons being operated by fluid pressure to shift the dogs outwardly and disconnect the pin and box from each other.

Abstract: An apparatus is provided capable of absorbing shocks due to decelerating forces caused by landing of a marine riser on a spider resting on a rotary table. The apparatus includes a hydraulic shock absorber mounted on the rotary table which supports the spider on which the riser lands, the load and shock of the riser moving pistons in cylinders to force hydraulic oil in the cylinders through an orifice into an accumulator, effecting shifting of an accumulator piston against compressed air in the accumulator, which can exhaust through a pressure relief valve. The above action decelerates the riser and spider. Upon removing the weight of the riser from the spider, the compressed air in the accumulator, supplied from the suitable source, moves the accumulator piston back to its initial position, which acts through the hydraulic oil to effect upward return of the pistons to their initial positions. The apparatus permits lateral translation of the spider and also its tilting in all directions to limited degrees.