Abstract: An articulated underwater cable riser system includes at least one articulated anchor section having a plurality of modular anchor segments and an articulated mid-span buoy having a plurality of modular buoy segments. The anchor segments and buoy segments encircle the cable and are secured adjacent one another in appropriate positions along the cable by cable clamps. The buoy segments and anchor segments are interfaced to the cable clamps by fairings which present smooth outlines for the anchor sections and mid-span buoy between the segments and the clamps to facilitate handling the anchor sections and mid-span buoy using conventional cable laying equipment. The anchor segments and buoy segments can be one-piece or, preferably, assembled by securing segment halves to one another. Bend limiters are coupled to at least some of the anchor segments to prevent an articulated anchor section from exceeding the minimum bend radius for the cable.

Abstract: A subsea flowline (10) deployed onto the sea floor (S) has tie-in points for interfacing other subsea facilities. Mudmats (14A, 14B, 14C) support hubs (16A, 16B, 16C) at the tie-in points. One embodiment shown in FIG. 2 has a cradle (22) supporting flowline (10) for relative rotative movement. Hydraulic jacks (26) are connected to arms (24) to position and maintain hub (16) in a vertical orientation. Another embodiment, shown in FIG. 3, has an outer swivel sleeve (21A) which is mounted on mudmat (14A) and receiving flowline (10A) for relative rotation. An annular fluid chamber or toroid (25A) provides fluid communication between flowline (10) and hub (16A) connected to outer swivel sleeve (21A). Another embodiment, shown in FIG. 4, combines the features and characteristics illustrated in FIGS. 2 and 3.

Abstract: A seabed flowline is connected to a substantially conventional tanker serving as a floating storage facility by a system comprising a three-leg mooring and a flexible riser. The mooring comprises anchors connected by anchor risers to a common node, and a mooring pendant extending from the node to the tanker. The flexible riser comprises a flexible rubber hose extending from the seabed to the tanker. The hose has a top section secured along part of the mooring pendant, and an intermediate section provided with buoyancy and restrained by a tether to maintain it clear of the anchor risers.

Abstract: An underwater pipeline apparatus for delivering a pig unit through an initially air or gas-containing sea-bed pipeline from an entry point toward an exit point. The apparatus includes an inlet conduit for coupling to a pipeline inlet port at a location behind the pig unit in its intended direction of travel, from the entry point to the exit point, having an opening to the sea to admit pressurised water into the pipeline under the head of water above the pipeline and means to regulate flow of water through the inlet conduit into a pipeline to regulate the speed of delivery of the pig unit along the pipeline.

Abstract: A method of connecting underwater pipelines by installation of a pipeline on a seabed fixed frame; laying of an outboard pipeline by a lay barge; installation of a subsea winch with the frame; actuation of the winch by a ROV to unwind the cable of the winch, aided by another ROV bringing and connecting the end of the cable to the outboard pipeline; winding of the cable and following deflection of the outboard pipeline up to the frame; installation of a metrology system to define the distance and angular misalignment between the two pipelines' ends to be connected; assembly of a connection system with telescopic capabilities using the measurements of the metrology system and using a dedicated frame installed on board a support ship; installation of the connection system on the seabed fixed frame and connection of the connection system with the pipeline ends.

Abstract: The invention relates to a system for pull-in and interconnection of two pipelines in subsea position, whereof one first pipeline initially is freely suspended, while one second pipeline for instance is mounted on a bottom based manifold frame. The end section on the first pipeline is provided with a socket-like termination with a front end, which is provided with means (17) for coupling of the terminator (8) to complementary pipe coupling means (29) on the second pipeline (19). The terminator (8) is provided with a laterally directed, longitudinally shaped anchor element (10), and the manifold frame (22) is provided with receiving means (24) for receipt and fixation of the anchor element (10).

Abstract: The invention provides a method for laying a pipeline on a floor located under water, wherein a pipe string is lowered from the pipe-bedding installation to the floor, characterized in that the part of the pipe string situated between the water surface and the floor is at least partially supported by bearing mechanism which engage on the pipe string, wherein an axial displacement is realized between the bearing mechanism on the one hand and the pipe string on the other.A heavy pipeline can hereby be laid on a deep seabed, for instance at a depth in the order of magnitude of 1-3 km, and/or the capacity of the draw benches on board the pipe-bedding installation can be reduced.

Abstract: The invention relates to improvements in an apparatus, such as pipelines (2) and associated equipment and to a method of making, insulating, providing buoyancy to, recovering and installing submarine apparatus. The marine or submarine apparatus comprises an impermeable enclosure (1) associated with the apparatus (2), which enclosure is tightly packed with hollow microspheres (3) to a density where, when submerged in use, the internal pressure of the microspheres is greater than or substantially equal to the water pressure on the apparatus.

Abstract: A system for accessing a subsea well in which a guide on a buoy system is tethered to the well head and the buoy is evacuated to render the guide arrangement rigid and a flexible coil tubing from a surface vessel above the well head is guided through this arrangement to the well head while adjustable buoyancy is provided along the flexible tubing between the vessel and the well head for controlling the profile of the tubing.

Abstract: A float (1) for floating flexible pipes has a multilayered foam body (3) that surrounds the floating flexible pipe (2), a textile cover (4) arranged on the foam body (3) and having in particular several transverse layers, and an outer covering (5) made of an elastomer, a thermoplastic elastomer or a thermoplastic material. The float (1) is further provided with a transverse textile reinforcement (6) that forms with the axis an angle from 75.degree. to 90.degree., in particular from 85.degree. to 90.degree..

Abstract: A clamp for a cylindrical object is provided which is formed of fibers in the form of woven fabric molded in a polymeric matrix. The clamps have two free ends through which one or two rods extend. The compressive force exerted by the clamp can be adjusted by adjusting the distance between the free end.

Abstract: An apparatus and method for laying underwater pipeline which includes a plurality of buoyancy control valves formed thereon. Each buoyancy control valve includes an air escape hole formed in the pipeline with a sliding weight member disposed in a first position upstream immediately adjacent to an air escape hole. During use, the air escape holes enables air to escape from the pipeline as it sinks at one end and descends to the sea floor in a catenary. As it descends to the sea floor, the sliding weight member slides via gravity from a first to a second position on the pipeline. When disposed in the second position, the sliding weight member covers the adjacent air escape hole. A hydraulically controlled restraining chain is disposed around the pipeline to control the sliding action of the sliding weight member until the pipeline has reached a pre-determine depth.

Abstract: A marine riser system which effectively combines rigid (e.g. steel catenary risers) with flexible flowlines. Basically, the steel catenary risers, which are merely the end portion of submerged rigid flowlines, are curved upward through the water in a gentle catenary path to a large, submerged buoy, which, in turn, is moored to the bottom by tension leg tether lines at a depth below the turbulence zone of the water. Flexible flowlines are fluidly connected to the steel catenary risers at the buoy and extend upward through the turbulence zone to the surface.

Abstract: The invention provides a method for laying a pipeline on a floor located under water, wherein a pipe string is lowered from the pipe-bedding installation to the floor, characterized in that the part of the pipe string situated between the water surface and the floor is at least partially supported by a bearing surface or trunk tubes which engage on the pipe string, wherein an axial displacement is realized between the bearing surface on the one hand and the pipe string on the other.A heavy pipeline can hereby be laid on a deep sea-bed, for instance at a depth in the order of magnitude of 1-3 km, and/or the capacity of the draw benches on board the pipe-bedding installation can be reduced.

Abstract: A hydrostatically releasable coupling assembly for releasably securing a buoyant object to a vessel with a lashing strap. The coupling assembly includes a pair of lashing plates, a cooperative latching mechanism carried by the lashing plates for releasably coupling the lashing plates together and a composite plunger assembly coupled to one of the lashing plates for movement between a release position and a locking position. The plunger assembly has a first diameter portion shaped for release of the latching mechanism for movement from an engaged position to a disengaged position when the plunger assembly is in the release position, and a second diameter portion formed of plastic and shaped to retain the latching mechanism in an engaged position when the plunger assembly is in the locking position.

Abstract: A device for mounting a flexible line including a curvature limiter. The device for mounting a flexible line on a structure, including a hollow rigid member forming part of the structure or fixed to the structure, and which the flexible line passes through after having been pulled with the aid of a pull cable fixed to one end of the flexible line, in particular on the end fitting mounted on the latter for connecting it to the structure, and a curvature limiter engaged on the flexible line and secured to fixing means able to interact with fixing means secured to the hollow rigid member for fastening the curvature limiter to the structure.

Abstract: A method for repairing a damaged subsea pipeline setting on the seabed includes the lowering of pipe support frames to the seabed and positioning the pipe support frames beneath the subsea pipeline on each side of the damaged pipeline section. The pipe support frames are expanded to elevate the damaged pipeline section. A pair of pipe attachment and receiving (PAR) assemblies are lowered to the seabed and positioned astride the pipeline on each side of the damaged section of the pipeline. The pipeline is gripped by the PAR assemblies. Cutting modules are lowered to the seabed and attached to each of the PAR assemblies. The pipeline is cut at each location with the cutting modules. The cutting modules are detached from the PAR assembly and a pair of docking modules are lowered to the seabed. One docking module is attached to each of the PAR assemblies. A telescoping spool section is lowered to the seabed and docked onto the docking modules.

Abstract: The present invention provides a method of cleaning a pipeline using a gel pig of a graft copolymer of a hydroxyalkyl cellulose prepared by a redox reaction with vinyl phosphonic acid. The gel pig is formed by hydrating the graft copolymer in an aqueous liquid. The gel pig is crosslinked by the addition of a Lewis base or Bronsted-Lowry base, to the gel in an amount sufficient to initiate crosslinking of the graft copolymer. Contaminants entrained in the crosslinked gel pig during the cleaning process may be separated by the addition of a pH reducing agent to the pig whereby the viscosity of the gel is caused to decrease. The gel may be used for further cleaning after contaminant separation by addition of an additional quantity of the Lewis base or Bronsted-Lowry base.

Abstract: An apparatus for dispersing chemicals into an underwater pipe comprising first and second chemical feed pipes, the feed pipes being mounted to an intake pipe forming part of the underwater pipe, the first feed pipe extending along the length of the intake pipe and being connected to the second feed pipe, the second feed pipe being mounted to the intake pipe at that portion of the intake pipe adjacent an intake pipe opening, the second feed pipe including a plurality of inwardly extending releasing valves for dispensing chemicals into the intake pipe, the chemicals being delivered to the second feed pipe through the first feed pipe. A cone-shaped device is also disclosed for inserting the first chemical feed pipe into the intake pipe, the cone-shaped device having first and second cone elements coaxially spaced apart to form an air pocket therebetween.

Abstract: For the balancing of seismic streamer cables (1) circular ring or sleeve-shaped weighted bodies are adjustably attached at desired intervals on the cable. The weighted bodies can be resilient for temporarily enlarging an opening (3) to receive the cable therethrough and for closing onto the cable in use, or can be circular cross-sectional bodies formed by two parts (4, 5, 4', 5') partially connected together by a single pin (6, 6') and fastened together by a spring pin (7) or hook-shaped pivoted lever (8) engageable with a retainer pin (10).

Abstract: The present invention relates to an improved flexible loading system which provides fluid communication between a subsea pipeline and a surface vessel including a hose extending from the subsea pipeline to a first buoyancy tank, a second hose extending from the first buoyancy tank to a central buoyancy tank, a second buoyancy tank, means connecting said second buoyancy tank to the sea floor and to the central buoyancy tank whereby the forces exerted on said central buoyant tank by said second hose and said connecting means are balanced to cause said central buoyancy tank to maintain a preselected position, a riser section extending upwardly from said central buoyancy tank and means on the upper termination for engagement by a vessel on the surface to raise said upper termination onto the vessel to complete the communication for moving fluids between the subsea pipeline and the vessel.

Abstract: A hydrodynamic cable deployment system suitable for deploying cable from a oil on a moving underwater vessel is disclosed. The present invention provides hydrodynamic assist means for cooperation with a system for the deployment of a cable tether used for communication between a marine vessel and an expendable or non-expendable device launched therefrom by providing means for generating hydrodynamic pressure to produce a current in the direction of cable deployment, assisting in the process of stripping the cable from the coil. The means for generating hydrodynamic pressure can be implemented via a pump, or via a water intake scoop which utilizes the forward movement of the marine vessel to force water therethrough. Additional pressure can be induced and concentrated in a predetermined direction through directional nozzles.

Abstract: A method is described for controlled bending of a pipeline during the laying thereof in the sea, utilizing bend controlling/stopping means which are mounted on the pipeline as a sleeve and interact with the pipeline. To achieve cold bending under controlled conditions, the pipeline is weight loaded internally at the selected bending zone. The weight loading may be achieved by means of a flexible string of weight elements and/or by introducing into the pipe a suitable heavy, readily flowable weight mass, for example, drilling fluid.

Abstract: A pipeline test bulkhead that can be neutrally buoyant under water for ease of transport under water is disclosed. The bulkhead is manually transportable under water without a crane regardless of the dry weight of the bulkhead out of the water and necessary for ease of transport under water in order to test each section of a pipe as it is attached during the construction of a pipeline under water.

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: This invention pertains to a method of installing well conductors in such a way that the load upon the platform is significantly reduced thereby also eliminating the need for additional framing members. In accordance with this method, an end region of a well conductor is plugged which, if the conductor has a diameter-to-wall thickness ratio of about thirty to one (30:1), will cause the conductor to achieve nearly neutral buoyancy. By selectively adjusting the buoyancy of the conductor, such as by flooding or de-ballasting, additional conductor lengths may be added without imposing an unduly large load upon the platform. In this fashion, a smaller crane will be able to lower the conductor string without the need for a much larger derrick crane, which may then be more efficiently used solely to upend and stab the elongated conductors through the platform.

Abstract: An apparatus is disclosed for balancing a seismic streamer cable. The housing is comprised of a first and a second valve coupled about the streamer cable. Each valve has a clasp adapted to engage a socket on the other valve to ridigly fasten the valves together about the streamer cable. The housing surrounds and retains weights applied to the streamer cable. An alternate embodiment is disclosed where the weight is integral with each valve. The exterior of the housing is designed to produce laminar flow conditions for the fluid passing over the housing as the cable is under tow, reducing ambient noise detected by the sensors within the streamer cable.

Abstract: A method of locally supplying slack to an axially tensioned length of pipeline spanning unsupported across an undulating seabed. During pipeline deployment, the pipeline is fitted with two weighted masses that will be positioned on either side of the undulation to be spanned. These masses will be spaced a predetermined distance from each other along the seabed, this distance being less than that between them along the pipeline. Also during deployment, the mid-region of this span is vertically deflected upward while retaining the axial tension in the pipeline. Once the pipeline is properly positioned, the vertical deflection of the pipeline is reduced thereby relieving the axial tension in the pipeline while also introducing sufficient pipeline slack such that the pipeline can closely follow the contours of the undulating seabed.

Abstract: A method and apparatus are provided for towing of a fluid containing tubular conduit above a sea bed floor and within a body of water, such as an ocean or river. First and second inflatable sealing elements are placed within the interior of the conduit with each of the sealing elements being movable from an unexpanded to an expanded position to effect a sealed interior section of the conduit. A movable pig is placed within the section and between the sealing elements and is activatable to displace fluid within the section when the sealing elements are in sealed relation to the conduit. A valve means is provided for discharge of the fluid out of the section during movement of the pig.

Abstract: Tendon segments are fabricated on a laybarge, then temporarily stored on seabottom. When a tension leg platform is moored, two tow vessels pick up one end each of the finished tendon and tow it to deep water, with the tendon in a catenary shape. Upon arrival in deep water, one end of the tendon is released and allowed to free fall to its uprighted position. A special work boat then transfers the tendon to the tension leg platform for final installation.

Abstract: A long pipeline is constructed at an on-shore site and then launched into a body of water. A tension force is maintained on the pipeline during launching to hold the pipeline off the floor of the body of water.

Abstract: Subsea pipelay is accomplished by flying the pipestring underwater with the use of wings which provide sufficient lift to maintain the pipestring off bottom as it is towed.

Abstract: A long pipeline is constructed at an on-shore site and is supported by floatable ground engaging supports. The pipeline is launched into a body of water while maintaining a tension load on the pipeline to hold it above the floor of the body of water. The floatable supports are retrieved after the pipeline is launched.

Abstract: The method of laying an underwater pipeline which is assembled in sections at the shoreline and conveyed from the shoreline along the bottom of a waterway, said pipeline being divided by separation means into a plurality of cylindrical sections provided with regulating means for selectively introducing thereto or removing therefrom ballast water or compressed air, which comprisesflooding at least a portion of the cylindrical sections in sequence as they are introduced into the waterway in order to achieve a desired residual weight,maintaining said desired residual weight by introducing compressed air into said cylindrical sections to displace excess ballast water contained therein, andcontinuing the layering of the pipeline along the bottom of the waterway by selectively supplying or discharging ballast water or compressed air to the cylindrical sections, andcompletely flooding the pipeline to complete its positioning at the bottom of the waterway and removing the cylindrical sections and the compressed air a

Abstract: A multi-component tubular structure for underwater conveyance of fluids comprising a plastic pipe, annular concrete ballast weights threaded along said pipe, and steel pulling rods. The pulling rods give the tubular structure tensile strength needed for underwater pipe laying, while the annular weights give overall uniform mechanical protection to the plastic pipe and a controlled negative buoyancy during the laying operation of the empty pie, and stability for the operating pipe. The tubular structure of the present invention combines the known advantages of plastic pipe, i.e., high flexibility, resistance to corrosion, with the advantages of coated steel pipe, i.e., ease of laying by the "bottom pull" method, high immersed wieght, and overall external mechanical protection.

Abstract: A technical hose with foam insert, expediently a maritime swimming hose for drawing-off oil, as well as to the process for the production thereof. The hose according to the invention consists of the elastic cross-linked elastomer layer containing also fibre-reinforcement, of the foam layer with closed cells arranged above said layer and assuring swimming ability, as well as of the new type of outer coating sheet.The outer coating sheet is a multi-layer system, the elementary layers are previously partially cross-linked, in their cross-section inhomogenous elastomer layers, stretched longitudinally in a given case, being interconnected and connected to the foam layer, respectively, by means of thermally and/or chemically activated adhesive layers.

Abstract: The pipeline (1) installed in an underwater environment (2) is engaged in a series of guides (4) placed above the seabed (3). These guides (4) are spaced from each other along a substantially straight-line direction (D) from land (5) towards the open sea (6). These guides (4) are connected by cables (7) to the seabed (3) and suspended from floats (8) placed at a sufficient depth (p) to minimize storm effects. Use particularly for installing a pipeline for withdrawing cold water from the depths of the sea to feed a tidal-thermal power station.

Abstract: An offshore oil platform (1) is provided with an improved riser handling system for making a subsea connection of a riser (6) to the platform, without the need for divers or boats to move the riser into position. A first coupling part (7) on the riser (6) is releasably coupled to a second coupling part (8) which in turn is releasably connected to a third coupling part (9) mounted in a submerged position on the platform. The second coupling part (8) is used as a guide to position the riser. The part (8) is coupled to cables (12,14) wound by winches (13,15). In use the riser can be released from the position shown in FIG. 1 to fall to the sea bed. To reconnect the riser, it is raised by davit (16) onto a platform (17), where the second coupling part (8) is fitted onto the part (7) on the riser. The cables (12,14), are then adjusted to draw the second coupling part (8) and hence the riser to the third coupling part (9) for connection therewith.

Abstract: The invention relates to the setting-down of a pipe in the sea using a setting-down line. The line is provided with sinkers at its lower end portion which tension the line and allow a reduction in the angle of general inclination of the line with the vertical and thus a reduction in the length of the line.

Abstract: A buoyant material/cable assembly is formed by placing elongated segments of a syntactic foam material around an underwater cable or the like to form a structure suitable for deep water applications. Banding in the form of oppositely directed spirals extend about the assembly and about its length to secure the segments together, to the cable, and against relative movement with respect to the cable. The bandings are fastened together at selected intervals along their length.Another form of the assembly consists of individual units of buoyant material formed of combined segments, secured together by bands. The units are spaced along the length of the cable.Another form consists of individual flotation units, or buoys, secured by flexible links to the cable. Oppositely directed spiral bandings extend along the length of the cable to secure the flexible links against movement with respect to the cable and with respect to each other.

Abstract: A method and apparatus is set forth in the present invention for supporting the weight of a marine riser by use of a passive tensioning system which utilizes a buoyant member located upon the upper end of the riser. The member has a vertical slot defined through its side such that the riser may access the member from a lateral direction. Such lateral access of the riser to the member allows these buoyant members to be changed from beneath the riser when maintenance and/or inspection is required on a particular member.Since the riser need only to move laterally to access any member, and the riser may be temporarily supported at the surface by other means, the lower end of the riser does not need to be disconnected from subsea equipment when maintenance and/or inspection operations are required on a buoyant member. Well operations do not need to be interrupted, therefore, during buoyant member maintenance operations.

Abstract: A flotation riser having a series of annular chambers with a riser string extending in free-standing relation through said chambers, means for supplying gas to the chambers to control buoyancy, means to supply gas to a plurality of the lowermost chambers to provide an emergency supply of deballasting gas, and means for remotely releasing said supply of gas into the chambers above to render the flotation riser free-standing to permit release from the floating platform during emergencies. A method of storing emergency deballasting gas and for emergency deballasting of the chambers to render the flotation riser freee-standing including the steps of supplying gas to the lowermost chambers, retaining the gas in said lowermost chambers, and remotely releasing the gas and conducting it to higher chamber to deballast such chambers sufficient so that said flotation riser is free-standing.

Abstract: Marine pipelaying is carried out from the surface of floating ice by use of modules which straddle a slot in the ice and carry the pipeline, each module having a large central float which is forced downward into the water and which functions to reduce loading on the sides of the ice slot.

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 to which the flowline is welded, a curved carrier pipe into which the end of the flowline is inserted, a bullnose to which the pullcable is attached, and a dovetail tenon which engages a dovetail receptacle to secure the terminal head to the subsea structure. The flowline terminal head may include buoyancy which keeps it free of difficult terrain in the vicinity of the subsea structure.

Abstract: Subsea pipe line sections adapted to be welded together into a continuous subsea pipe line are provided with a weight coating which, apart from its weighting function, also serves to protect the pipes. The weight coating comprises a composite material substantially consisting of a granulated iron ore in a matrix of a thermosetting resin, covered by a high strength durable plastic tube.

Abstract: In laying an electric cable underwater, the finishing end of the cable is brought ashore by laying the cable end portion (from the cable laying ship) along a course parallel to the shore and as close to the shore as the ship can reach, then pulling the cable end to shore using a rope, pulling the cable end along the shore to the intended landing point, and then pulling the cable end in-land along the intended laying line until the whole cable is positioned along this line. Buoyancy devices are attached at intervals to the cable end portion for the duration of the landing process, to facilitate the sliding movement of the cable over the bottom.

Abstract: The sealed shell of a nuclear steam generator is penetrated through a fluid lock by an elongated assembly including an axial fiber optic cable. Fluid pressure chambers within the assembly are selectively pressured to control the movement of the fiber optic head in visual inspection within the shell. Liquid is selectively introduced into the chambers to control buoyancy of the assembly.

Abstract: A pressure-actuated release mechanism is assembled using a prebuckled pipe segment as a pressure-triggering mechanism. The trigger mechanism is employed to attach buoys to an offshore structure or pipeline under construction. The attached buoys move with the structure or newly added pipe string toward the sea bottom, easing the descent. As a preselected external pressure is sensed, the buckle in the pipe segment propagates and the trigger mechanism actuates, releasing buoys from the structure or pipeline as each buoy in turn reaches the same depth or pressure.

Abstract: A method and apparatus are provided for laying an offshore pipeline or flowline bundle to a deepwater subsea structure. The pipeline or flowline bundle is laid along a prescribed path, preferably U-shape, such that a pullhead at the terminus of the pipeline or flowline bundle falls just short of the subsea structure. A pull-in tool connected to the pipeline or flowline bundle by a short length of pull cable is then landed on and latched to the subsea structure, and the pipeline or flowline bundle is pulled up to the subsea structure by the pull-in tool and pull cable.

Abstract: Apparatus for preventing flow of water from a first underwater pipeline portion forward of the apparatus to a second underwater pipeline portion rearward of the apparatus. At least one wedge-shaped member is mounted on a carriage of the apparatus for grippingly engaging the internal wall of a pipeline for preventing movement of the apparatus in a rearwardly direction upon application of force to the carriage urging the carriage in a rearwardly direction in the pipeline. In order to provide frictional contact with the pipeline wall so that gripping engagement thereof may be effected, the member is continually urged into sliding engagement with the pipeline wall during movement of the apparatus through the pipeline in a forwardly direction.