Abstract: An improved pipe section is disclosed for installation into a subsea pipeline. A pipe section in accordance with the present invention provides a length of pipe having a pipe wall and at least a first bearing shoulder projecting circumferentially outward from the pipe wall whereby the pipe section may be handled by supporting the pipe section from the first bearing shoulder during installation. The first bearing shoulder also prevents propagation of buckling failure in the subsea pipeline constructed from such pipe sections and the first bearing shoulder remains available for pipeline retrieval operations in the event of localized failure in the subsea pipeline.

Abstract: A method for laying underwater pipelines in deep water, using the J launching technique, comprising joining together mixed-structure pipes consisting of a steel core reinforced with a composite material consisting of a hardenable material containing continuous fibers and in which:the continuous fiber is wound about the steel core as a helical winding which forms an angle of between 65.degree. and 87.degree. with the pipe axis;the ratio of the thickness of the composite layer to the thickness of the steel core is between 2 and 8;the weight of the mixed-structure pipe in water is between about 40 and 100 kg/m.

Abstract: A pipeline connector and repair system for sealingly connecting the ends of first and second pipes together without welding or bolting. First and second connectors are provided at each end of a pipe joint and are inserted between the ends of the first and second pipes to be connected, the connectors are extended outwardly for enclosing the ends of the first and second pipes, and dual slip means and dual seal means in each of the connectors are hydraulically set for making the repair.

Abstract: An apparatus for near vertical laying of pipeline offshore. A support frame and movable deck on a lay vessel support a tower at the desired angle for pipe laying. The tower has a travel block that is movable between open and closed positions for receiving a pipe section and supporting the weight of the pipe or pipeline. The travel block is adapted for movement along the length of the tower for raising or lowering the pipe and pipeline. A pedestal that is movable between open and closed positions for receiving a pipe section and supporting the weight of the pipeline is positioned near the bottom of the tower and adapted to transfer the weight of the pipeline from the travel block to the pedestal without the need to open the travel block. A strongback with adjustable clamps is used to grasp a pipe section from a ready rack and transfer the pipe section into the tower for addition of the pipe section to the pipeline. The strongback is guided into and up the tower by rails.

Abstract: A method of testing snap type pipe connectors utilizes the same clamp that is used to clamp the pipe connectors together. The connectors are a part of pipe sections, with each connector having a profile that radially interferes with the other so that under straight axial compression, the connectors are snapped together. The clamp tool that applies compressive force will be reversed after the compressive force has been applied to apply a tensile test force. The test force is greater than the compressive force required to snap the pipe connectors together.

Abstract: A subsea system for oil or gas production and water injection operates without divers' assistance and with guide-cables and includes a template (50) equipped with ten drilling mouths (53) arranged in two rows of five. Each drill mouth (53) has a guidepipe (54). The upper extremity of the guide-pipe presents an external section for locking purposes. A guide-base (55) is provided with four posts (56) removable by a ROV. A central space is provided in the template for the setting of a manifold (60) through four posts (63) to guide the installation and devices which ensure the final positioning of the manifold (6) within established tolerances. Bases of export-line terminals (64) are located in one of the extremities of the template (50) Each base (64) is provided with two guide-posts removable by a ROV, in addition to reaction posts (66) which orient the lowering of the pulling and connection tools and transfer the stresses to the structure of the template. Receptacles (67) lock the export-line terminals.

Abstract: A method of laying a pipe (1) on a sea floor for the transportation of a fluid, having a temperature and/or a pressure exceeding the temperature and pressure of the surroundings involves the pipe (1) being provided with prestressing. This prestressing must be of such an order than it is at least substantially able to neutralize the effect on the pipe (1) of the temperature and the pressure difference during use. Prestressing may be provided by a prestressing device (6) which works between an anchor (7) and a clevis (4) welded onto the pipe.

Abstract: A pipelay apparatus and method comprising a steel turntable and a stinger pipe guide which can be supported on the construction deck of a repair vessel or drill ship are provided. The turntable is framed so that loads from two hanging pipes can be securely supported. The table-supported framing members can be moved so the load centerline for each pipeline can be placed an appropriate distance from the center of turntable rotation, which is useful where the two pipelines are of different diameters. This apparatus permits a vessel to simultaneously handle different sizes of pipe and pass large diameter appurtenances without modifying the stinger pipe guide.

Abstract: The laying of a pipeline on a surface located under water is to a great extent continuously performed because the pipes are arranged in line with a pipe string by means of at least two alternately used pipe carriers.

Abstract: A hydraulic control umbilical is disclosed for supporting a plurality of hydraulic control lines along a riser between a surface facility and a subsea completion. The umbilical provides a skin encircling the riser substantially its entire length with means for supporting the skin about the riser and means for supporting the hydraulic control lines within the skin. A method for deploying and retrieving the hydraulic control umbilical is also disclosed.

Abstract: An apparatus and method for underwater aligning and connecting of two pipes used in directional drilling and particularly trenchless beach crossings. An alignment cable is connected between the ends of the two pipes and is tensioned to bring them into axial alignment. A rigid supporting platform is positioned on the sea floor. Securing clamps are mounted on the platform to align the two pipes. To thread the pipes, one pipe rotates about the joint axis.

Abstract: An apparatus and method for underwater aligning and connecting of two pipes used in directional drilling and particularly trenchless beach crossings. An alignment cable is connected between the ends of the two pipes and is tensioned to bring them into axial alignment. A rigid supporting platform is positioned on the sea floor. Securing clamps are mounted on the platform to align the two pipes. To thread the pipes, one pipe rotates about the joint axis.

Abstract: A liner or other elongated duct is made by joining lengths of thin-walled polyethylene fusion. Typical thickness 2-4 mm, diameter 200 mm. Pipe ends are clamped in clamps which restore circularity. The ends are trimmed leaving aligned ends normal to pipe length. The clamps force the ends against a heated body, which is retracted and the ends are then forced together. The total heating period, say 15 seconds, and the periord between separation from the body and engagement of the ends, say 1 second, are very short. Good joint strengths and small beads result. The liner can be pulled into burst cast-iron gas main before a new main is passed through the liner; or the liner is a seal in a pipe. The method is applicable to other polyolefins e.g. polyropylene.

Abstract: A stabilizing system for use in joining flanged pipe sections together in an underwater environment including at least one flange stabilizing element having a back plate portion with a support portion affixed thereto and extending orthogonally out therefrom a distance substantially in excess of the thickness of one flange, providing laterally spaced lines of support adjacent to the front of the flange at different vertical positions along its width defining a curved support tray area consistent with the curvature of the flanges of the pipe sections to be joined. At least one stub also extends orthogonally out from said back plate portion having a diameter less than the diameter of the bolt holes of the flanges.

Abstract: Device with valve function which can be brought into and out of a pipeline and parked in the same. The device comprises a channel for throughflowing fluid, a valve (2) which is medium controlled and/or remote-controlled, a parking brake/packer seal unit (9) which with limited force can be brought to bear against the wall of the pipeline, a cylindrical wire anchor (1) with an external diameter which is slightly lesser than the internal diameter of the pipeline and can be brought into pressure contact with the pipeline.

Abstract: A lower portion of a subsea oil delivery hose is held taut between bouyant devices installed on the hose and a stationary point on the subsea floor. A portion of the lower part of the hose, connected to the stationary point, has a curved portion that is concave in the direction of a wellhead to which the hose is connected.

Abstract: Method and apparatus for remotely connecting an offshore structure to an underwater pipeline using a remotely operated vehicle (ROV). The structure has a bell-mouthed bending guide at its base through which a winch line from the surface passes and is temporarily looped back and attached to an accessible place on the structure. Using the ROV and a surface tended messenger line the pull-in line is attached to a terminal assembly at the end of flexible pipe attached to the pipeline. The terminal assembly is pulled in horizontally to the guide, arcuately through the guide and then from the guide in general vertical alignment with a pipe end receiver assembly on the structure above the bending guide. At a location near the receiver assembly a towing head is removed from the terminal assembly and a second pull-in line is attached to the terminal assembly. The two pull-in lines are attached to opposite sides of the terminal for balanced pulling of the terminal assembly to connection with the receiver assembly.

Abstract: Apparatus for laying large pipe sections underwater without on-site manual participation. A beam is releasably attached to a pipe section that is to be lowered to the floor of the water body and attached to the open end of the previously laid pipe section. A positioning fork depending from the beam is settled onto the prior pipe section with the fork legs straddling the pipe and assuring alignment of the pipe ends. Positioning rams in cooperation with landing gears on the fork legs achieve concentric abutment of the end flanges. The flange on the new pipe section is rotatable and a positioner from the beam is releasably attached to the rotatable flange and rotated therby to align bolt holes through the flanges. A wrench carried on a rigging releasably attached to the new pipe section behind the flange is movable between the bolt holes and pushes bolts partially pre-inserted in the bolt holes through the flanges and into engagement with nuts pre-positioned behind the bolt holes of the fixed flange.

Abstract: Connecting a tubular string to a subsea installation. The tubular string includes a short first section and a longer second section. The length of the first section is approximately one-half the depth between the lowermost guide ring of a fixed platform and the top of the subsea installation. One end of the first section is provided with a connector and the other end with a connector and a funnel. The first section is lowered through the guide rings and connected to the subsea installation. One end of the second section is provided with a connector and the second section is lowered through the guide rings and into the funnel. Since the two adjacent ends are about midway between the subsea installation and the lowermost guide ring, the adjacent ends are easily bent into alignment by the camming action resulting when the end of the second section slides along the inside tapered surface of the funnel when the axes of the platform and subsea installation are offset.

Abstract: The invention provides a method of assembling and installing pipes comprising disposing at least one cable between a first station and a second station; attaching and clamping a first pipe to the cable at or adjacent one of said stations; moving the pipe away from said one station with the cable; connecting a second pipe to the first pipe and attaching and clamping the second pipe to the cable at or adjacent said one station; repeating the connecting, attaching and clamping operation to provide an elongate connected sequence of pipes attached to and clamped to the cable; and drawing the cable away from said one station towards the second station to move the sequence of pipes into its desired position between the first and second stations.

Abstract: Apparatus for connecting portions of subsea flow conduits includes a stab member with a body and having a bore therethrough, one end of which exits from the stab body through a side port. A stab receptacle includes a bore for receiving the stab body, and a flow bore intersecting the receiving bore and leading to the exterior of the receptacle. The side port communciates with the receptacle flow bore when the stab member is landed in the receiving bore. Seals above and below the side port seal the receiving bore above and below the intersection of the receptacle flow bore and receiving bore. The cross-sectional areas of the seals exposed to internal fluid pressure are substantially equal, resulting in zero blow-apart force on the stab connection. Alternatively, the lower seal can have a larger exposed cross-sectional area than the upper seal, resulting in a net force tending to hold the connection teogether.

Abstract: A subsea connection assembly including a connection box having an open top and provided with a plurality of pipe segments coupled thereto, each pipe segment having an outlet end near the open top of the connection box. The pipe segments have their inlet ends coupled to a manifold assembly having connections to subsea wells. Guide wires are attached to the connection box for guiding a frame downwardly from a floating vessel or platform on the surface of the sea, the frame being operable to carry the lower ends of a plurality of fluid conductors downwardly to the connection box so that such lower ends can become connected to the outlet ends of the pipe segments.

Abstract: A method and apparatus is presented for connecting a flexible conduit bundle from a subsea wellhead to a floating platform. Movement of the floating platform relative to the subsea wellhead is compensated for by arranging the conduit bundle to be suspended in a catenary manner between the wellhead and the floating platform. The catenary form of the conduit bundle is maintained by bending the circuit around anchor blocks located a selective distance from the subsea wellhead.

Abstract: Disclosed in a method of and apparatus for lowering pipe strings and other objects, particularly pipe strings carrying anodes for cathotic protection, into and through the support structure of an offshore plateform. Skid beams are inserted into the support structure of the offshore platform below the top deck of the platform and above the water level, preferably at the plus twelve level of the structure. Mounted to the skid beams are winch and derrick means. The skid beams are inserted into the structure such that the winch and derrick means are positioned over the point at which the pipe string is to be lowered through the structure. The skid beams cantilever out from the structure such that they extend well beyond the outside perimeter of the top deck. The skid beams also serve as track for a trolley. Pipe string sections can be delivered to the trolley either from the top deck of the platform or directly from a barge.

Abstract: A subsea flowline connector for remotely connecting and releasing a first flowline such as a peripheral flowline on a marine riser to a complementary second flowline at a submerged location without the use of divers. Further, the seals in the connector may be remotely replaced without the need to bring the connector to the surface. Further, in one embodiment of present invention, a bundle of control/supply lines can be remotely connected to respective submerged lines at the same time as the flowline is connected.

Abstract: A subsea connector system for connecting the lower end of a structural core of a marine riser to a base which has been preset on the marine bottom. The box member of the connector system forms an integral part of a tapered section which, in turn, forms the lower end of the riser. The connector system, in a preferred embodiment, incudes a self-contained source of hydraulic fluid under pressure which actuates the connector to a locked position upon command. The connector also includes a back-up means for remotely locking the connector and three separate means for remotely unlocking the connector.

Abstract: The present invention provides a method and apparatus for connecting a flowline to a subsea structure. A riser and flowline connection tool are deployed downwardly to the subsea structure and a flowline terminal head, which is at the end of the flowline, is pulled to the flowline connection tool by means of a pullcable. Then the flowline terminal head is secured to the subsea structure and the flowline connection tool is recovered to the surface. The flowline terminal head consists of a connector hub with clamping surface to which the flowline is welded, and a flexible carrier pipe of interlocking metallic rings into which the end of the flowline is inserted. The carrier pipe limits the curvature of the flowline as the terminal head is bent into alignment with a flowline receptacle of the subsea structure. The flowline terminal head may include buoyant encircling rings which keep it free of difficult terrain in the vicinity of the subsea structure.

Abstract: A floating tube apparatus (7) for providing a sealed, reversible and remote-controlled connection between ducts, in particular underwater ducts or difficultly accessible ducts, provided with complementary connectors to connectors (8, 9) carried by the floating tube at its ends. The apparatus comprises a positioning device (17, 21, 22, 23, 24) for positioning the floating tube (7) relative to a reference plane defined by a rectilinear rolling path of fixed structure (18). The positioning device includes a ball joint (23, 24) mounted on the middle of the tube (7) and three carriages mounted on one another in such a manner as to enable each to be displaced rectilinearly along a displacement axis which is perpendicular to the displacement axes of the other two, the transfer carriage (17) which carries the other two carriages moving along the rolling path under the action of jacks (31A, 31B), and the carriage (22) carried by the other two carriages itself carrying the ball joint, and consequently the tube.

Abstract: Apparatus for enabling a self-contained submersible module including a length of conduit for connection to a collector to be repetitively put into place and removed. The collector (3) is located on the sea bed, and said length of conduit (14) and said collector (3) have mating ends fitted with a releasable connector suitable for establishing said connection when the ends to be connected come into end-to-end engagement. The length of conduit (14) is mounted in the module (2) on a carriage (7) to enable said length of conduit to be moved out from said module to bring one of its ends (13) into contact with the end (5) of the collector. Once the length of conduit has made connection with the end of the collector, the carriage also enables said length of conduit to be moved in the opposite direction pulling said collector with it in order to connect the other end of the conduit to a well head (1).

Abstract: A pipe-welding assembly is provided in which single-pass welding of one pipe length to another is accomplished by gas lasers mounted to rotate around the axis of the pipes to weld the pipe ends together in the gap between two axially aligned spaced pipe clamps. Weld-testing units are similarly rotated around the pipe axis. The pipe-welding assembly is mounted on a gyroscopically-stabilized platform, which can be located on a pipe-laying land vehicle, or on a pipe-laying ship for laying pipe lines on the ocean bed. If the ship is equipped with a pipe feed tower, with the pipe-welding assembly positioned at the base of the tower and a drawbridge provided for elevating successive pipe lengths angularly into the tower, pipe laying can be performed in the "J" configuration. If the tower is mounted so that it can be inclined angularly into a position approaching the horizontal, and the pipe-welding assembly can be similarly rotated on its stabilized platform, pipe-laying can be performed in the "S" configuration.

Abstract: A device for permitting the relatively precise positioning of two geometrical axes respectively of two elements at least one of the elements being associated with means capable of assuring its displacement characterized in that it comprises in combination at least two acoustic emitters-receivers disposed in a first plane substantially perpendicular to one of said geometrical axes, said axis being defined as the first axis, and capable of emitting toward said axis, said two emitter-receivers not being located on a same line passing through said first axis and in that it comprises a third emitter-receiver situated outside of said plane.

Abstract: This connection means comprises a male connector (1) with a circular groove (5) and a female connector comprising a body (2), a cap (3) and a sleeve (4). The cap (3) hangs from the bottom end of body 2 within which it is able to partly slide. The cap has a bearing surface (7) bearing on the male connector (1) and its bottom part (9) covers the male connector. This bottom part is provided with a circular series of openings (10) each equipped with a finger (11) operable to slide radially. These fingers cooperate with windows (27) in a conical wall (26) of the sleeve (4). Connection is made by gravity, by body 2 pushing down on sleeve 4, which slides downward causing the fingers (11) to slide radially inward. Disconnection is accomplished by sending oil pressure through purposely provided channels (35, 33, 30) into a chamber (20), causing the sleeve (4) to slide up and the fingers (11) to retract.

Abstract: In order to lay down a pipeline, which consists of socket pipes (9), a device which consists of a frame with two side walls (1) can be used. On the outside of the side walls (1) there is mounted a number of engines (7) which can lead an intermediate cross member (2) to the front and to the rear of the frame.Moreover there is in the front of the frame mounted a profile cutter (6) which can be led down into the underlying layer and excavate a bearing (8) for the socket. By means of this device an excavation can be made and a pipeline, which is supported in its full length, laid down. In this way even the strictest demands to laying down a pipeline can be complied with.

Abstract: Propagating buckle chambers, vessels or jugs are employed as in-line plugs in a pipeline. In order to test connectors before flooding the pipeline, the chambers, vessels or jugs are set to trigger at a pressure higher than test pressure.

Abstract: A gyro compass positioning apparatus is disclosed for use in lowering and accurately orienting a first object such as an underwater pipeline junction manifold to the floor of a body of water. The gyro compass positioning apparatus comprises a north seeking gyro compass in combination with a closed circuit television camera, all enclosed in a pressure housing. The closed circuit television camera is mounted above the north seeking gyro compass such that it is continuously viewing the orientation of the needle of the compass and displaying this orientation on a television monitor which is located on the surface ship. The first object or underwater pipeline junction manifold is attached to the bottom of the pressure housing by a mounting bracket and in predetermined orientation thereto.

Abstract: An eccentric hinge is provided for laying submarine pipelines which facilitates joining long segments of the pipeline by raising adjacent ends of the segments, attaching the hinge thereto, and lowering the segments and hinge to the sea-floor while remotely applying tension to one of the segments.

Abstract: A header or other pipe under pressure which is blanked at its terminal end by a closure plate is extended without the need of a shutdown or the construction of bypass piping. In a series of steps in the method disclosed, alternate bolts in the ring of bolts holding the closure plate to the annular flange of the existing pipe are variously repositioned or replaced to accomodate the construction of the extension while maintaining an adequate seal to prevent the escape of the pressurized fluid in the pipe. A structure which is installed as a product of this method and an apparatus used in this installation are also disclosed.

Abstract: Method for placing two submerged elements in a relative determined position, particularly in view of their mutual connection, comprising a first step of controlling the relative displacement of said elements on the basis of the measurement of electric values so as to ensure the alignment of a central point of one end of one element with the longitudinal axis of the other and a second step of progressively bringing the two elements in contact with each other by their relative displacement controlled on the basis of the measurement of their relative distance and mutual inclination angle, by means of acoustic emitters-receivers.

Abstract: Sections of pipe for an underwater pipeline are laid by first positioning a support frame on the underwater terrain generally about the position for a section of pipe and then lowering a longitudinal pipe support and a section of pipe into engagement with the support frame. The position of the longitudinal pipe support on the support frame can be adjusted for proper positioning of the section of pipe with previously laid pipe. After a section of pipe is laid and supported by backfill, the underwater support frame is moved to the position for the next section of pipe. The support frame includes first and second transverse members each having a saddle for receiving a seat portion of the longitudinal pipe support. The saddles are moveable along the transverse members for adjusting the position of a section of pipe, and one of the transverse members is moveable. The longitudinal pipe support is moveable on a roller in the saddle on the fixed transverse member.

Abstract: A plugging apparatus is disclosed for plugging the bore of a pipe at a selected location and withstanding a pressure differential thereacross that may equal or exceed the designed working fluid pressure of the pipe and includes a body adapted for insertion into the pipe bore and for axial movement within the pipe, the body including an upstream pressure head having a selected projected area and a support structure (which can conveniently be pigging discs) attached to and cooperating with the body for supporting the body axially in the pipe during movement in the pipe. A pipe gripping structure is carried by the body, locking engagement with the inside surface of the pipe. A plurality of annular elastomeric sealing members having a selected annular area are circumferentially mounted on the body.

Abstract: A modular undersea oil production plant having at least one satellite unit whose product is conveyed by a collector pipe (10) towards a central structure (4) in which operating modules (5,6) are grouped together, said product being removed from said operating modules, wherein said satellite unit has a wellhead (1) linked by a connector (13) to the upper portion of a pipe (44) in a drill hole, an individual auxiliary module (3) which can be raised being associated with said wellhead, said module containing the control and operation components and being connected firstly to said wellhead by a first connector (23) and secondly to one end of said collector pipe (10) by a second connector (24), said wellhead (1) and said auxiliary module (3) being installed on a template (2) in two distinct cavities whose shape is complementary to that of said wellhead and of said auxiliary module which has means for disconnecting it from the collector pipe and from the wellhead and for removing it from the template (2), said disc

Abstract: A collar forming machine for the repair of submerged pipelines is provided comprising a forming module having the central shaft (10) passing through the body (12) of a main jack, a piston (18) sliding on the shaft and carrying at its end a forming punch (13), the shaft carrying in its part intended to penetrate inside the tube to be repaired internal locking means (14) to be forcefully applied to the inner face of the wall of the tube and capable of transferring the forming force to the tube itself, further comprising external locking means (17) applied to the external face of the wall of the tube to prevent deformation thereof.

Abstract: A process for tapping a region of a pipe placed on a sea bed utilizes a working platform which is installed vertically above the region of the pipe to be tapped, the platform being adapted to receive a support girder which can be lowered from the surface of the sea onto the working platform and be engaged therewith and then lifted off the platform. The platform is adapted to receive successively a plurality of modular tool-carriers provided with tools for carrying out a variety of operations on the pipe, the operations including concrete stripping, removal of anti-corrosion covering, transverse cutting, internal brushing, and making the longitudinal weld flush.

Abstract: A method for joining of pipes, especially large concrete pipes, heretofore been a comparatively cumbersome procedure necessitating the use of special tools by means of which a pressure has been exerted on the back end of the pipe to push it towards the last of the previously laid pipes.

Abstract: A method and apparatus are provided for positioning, aligning and interfacing a towed pipe string to a previously installed pipe segment by positioning an end of the pipe string within a predetermined range of an end of the pipe segment, attaching a first gripper block to the end of the pipe string, moving an alignment tool over to the pipe segment while paying out connecting means between the alignment tool and the first gripper block, attaching a second gripper block of the alignment tool to the end of the pipe segment, tensioning the connecting means to draw the end of the pipe segment and the end of the pipe string within close proximity of each other, attaching a third gripper block of the alignment tool to the end of the pipe string, the second gripper block and the third gripper block being in a spaced-apart position, and drawing the second gripper block and the third gripper block toward each other, thereby aligning the end of the pipe string with the end of the pipe segment.

Abstract: A plugging apparatus is disclosed for plugging the bore of a pipe at a selected location and withstanding a pressure differential thereacross that may equal or exceed the designed working fluid pressure of the pipe and includes a body means adapted for insertion into the pipe bore and for axial movement within the pipe, the body means including an upstream pressure head having a selected projected area and support means (which can conveniently be pigging discs) attached to and cooperating with the body means for supporting the body means axially in the pipe during movement in the pipe. A pipe gripping means is carried by the body means, locking engagement with the inside surface of the pipe. A plurality of annular elastomeric sealing members having a selected annular area are circumferentially mounted on the body means.

Abstract: A latching system for releasably connecting two conduits which includes a base member having at least one upwardly extending conduit and a locking plate supported thereon, and a latch support member including at least one downwardly extending conduit and having a locking mandrel depending therefrom. The locking mandrel is rotated via the downward movement of a piston within a cylinder, the piston having a spirally splined shaft mounted thereon which mates with a spirally splined surface associated with the locking mandrel, whereby downward movement of the piston and spirally splined shaft causes the locking mandrel to rotate and lock into engagement with the locking plate.

Abstract: This invention relates to a floating production system for offshore development of oil and gas wells which employs an underwater buoy to decrease tension on flexible riser pipes used to connect a subsea pipeline to the floating vessel. The underwater buoy utilizes a cradle assembly having a drag balancing tail assembly to counteract the twisting moment applied to the cradle by current drag forces.

Abstract: Pressure-tight pipeline plugs are used in subsea connection operations to achieve a lightweight pipe condition which facilitates alignment by easing handling problems. An internal plug is provided for this purpose which is particularly useful for connection operations using a pipelay vessel, and which is capable of sealing, remotely releasing and then being pumped out of the line to a terminus.

Abstract: A subsea pipeline hub is connected to the hub of an adjacent spool piece connected to an in-place manifold of a subsea structure used in the production of oil and/or gas. The pipeline hub is positioned relative to the opposing spool hub and a remotely operated pipeline connecting tool is lowered from the water's surface to the subsea structure using guidelines and structural guidance for alignment of the pipeline hub with the spool piece hub. The spool piece hub is then drawn to the pipeline hub and the hubs are clamped together by operation of the connecting tool. The seal in the connection can be tested by means of the connecting tool. The spool piece may be retrieved and replaced by the connecting tool if maintenance is needed. Connecting tool operations are powered by hydraulic fluid and controlled from the surface. The pipeline hub may be lowered vertically and pivoted into its position adjacent the spool piece or may be pulled into that position.