Abstract: The present invention relates to an apparatus for and a method of holding high top tension pipeline (101) during pipe-lay from a rolling and pitching vessel (730). In one implementation, a clamp system (711, 712) for supporting a pipe on a vessel includes a first clamp for coupling to the pipe and a second clamp for coupling to the pipe. The second clamp is disposed above the first clamp. At least one of the first clamp or the second clamp is movable relative to the other of the first clamp or the second clamp.

Abstract: The present invention relates to an apparatus for and a method of holding high top tension pipeline (101) during pipe-lay from a rolling and pitching vessel (730). In one implementation, a clamp system (711, 712) for supporting a pipe on a vessel includes a first clamp for coupling to the pipe and a second clamp for coupling to the pipe. The second clamp is disposed above the first clamp. At least one of the first clamp or the second clamp is movable relative to the other of the first clamp or the second clamp.

Abstract: A turntable assembly for performing welding or other operations in a pivotably-mounted J-lay tower is disclosed. The assembly includes an annular turntable supported by a base frame to turn about a pipe string in use and a tilt-compensating mechanism acting on the base frame to level the turntable as the tower pivots in use. The tilt-compensating mechanism includes at least one support that is driveable up and down with respect to the tower. In the embodiment disclosed, the support is a carriage movable along an upright track that pivots with the tower.

Abstract: A method of abandoning a pipeline during subsea pipelaying from a pipelay vessel includes suspending the pipe string from a tendon element of an abandonment string and engaging further tendon elements to an upper end of the abandonment string while lowering the pipe string to a handover depth. At the handover depth, tension is applied via a wire to the top of the pipe string at an acute angle to the launch axis. This deflects the pipe string from the launch axis into axial alignment with the wire to transfer the weight load of the pipe string to the wire, whereupon the abandonment string can be decoupled from the pipe string. Recovery of the pipeline from the seabed can be effected by a reverse process.

Abstract: A method of abandoning a pipeline during subsea pipelaying from a pipelay vessel includes suspending the pipe string from a tendon element of an abandonment string and engaging further tendon elements to an upper end of the abandonment string while lowering the pipe string to a handover depth. At the handover depth, tension is applied via a wire to the top of the pipe string at an acute angle to the launch axis. This deflects the pipe string from the launch axis into axial alignment with the wire to transfer the weight load of the pipe string to the wire, whereupon the abandonment string can be decoupled from the pipe string. Recovery of the pipeline from the seabed can be effected by a reverse process.

Abstract: An elongate sling section is disclosed. The elongate sling is cooperable with like sling sections to form a sling for use in abandonment or recovery of a pipeline. The sling section includes end-pieces at five opposite ends and complementary connector formations associated with each respective end-piece. Each connector formation is cooperable, in use when forming a sling, with a complementary connector formation of a neighbouring sling section in the sling. The sling section further includes a tensile load-bearing sling element extending between the end-pieces and a sleeve around the sling element.

Abstract: A turntable assembly for performing welding or other operations in a pivotably-mounted J-lay tower is disclosed. The assembly includes an annular turntable supported by a base frame to turn about a pipe string in use and a tilt-compensating mechanism acting on the base frame to level the turntable as the tower pivots in use. The tilt-compensating mechanism includes at least one support that is driveable up and down with respect to the tower. In the embodiment disclosed, the support is a carriage movable along an upright track that pivots with the tower.

Abstract: An elongate sling section is disclosed. The elongate sling is cooperable with like sling sections to form a sling for use in abandonment or recovery of a pipeline. The sling section includes end-pieces at five opposite ends and complementary connector formations associated with each respective end-piece. Each connector formation is cooperable, in use when forming a sling, with a complementary connector formation of a neighbouring sling section in the sling. The sling section further includes a tensile load-bearing sling element extending between the end-pieces and a sleeve around the sling element.

Abstract: A method and apparatus for laying pipeline from a vessel. The vessel has pipelaying equipment including apparatus for fabricating pipeline along a fabrication axis, a stinger pivotable between a deployed configuration and a retracted configuration, and a tower pivotable between a lowered configuration and an elevated configuration. The method includes a) pivoting the stinger away from the deployed configuration and into the retracted configuration when it is desired to attach a module to the pipeline, b) before or after step a) attaching a module to the pipeline. Further, c) lowering the section of pipeline from the tower along the departure axis until the attached module is below the retracted stinger, and d) pivoting the stinger away from the retracted configuration and into the deployed configuration to allow continued laying of fabricated pipeline.

Abstract: The present invention relates to a method and apparatus for laying offshore pipeline from a reel lay vessel. The invention involves providing a pipeline laying tower with a travelling clamp, which can be used to suspend the pipeline from the vessel, and a tensioner apparatus on the same tower, for providing a clamping force which can be used to suspend the pipeline from the vessel. The travelling clamp and tensioner apparatus may either be used separately or in conjunction with one another during the laying operation. The invention allows pipeline to be laid in very deep water.

Abstract: A vessel for laying rigid tubular pipes has two vertically upright wheels for storing tubular pipe which is wound with plastic deformation. An inclinable laying davit is arranged approximately above a moon pool. An arched chute deflects the pipe at the top of the davit, followed down the davit by a pipe-straightener and tensioner. The mid-planes of the two adjacent wheels face approximately towards the davit, and the mid-planes intersect in the vertical longitudinal mid-plane of the vessel.

Abstract: Induction heating apparatus for use in welding an end of a first length of pipe (26) to the exterior surface of a second length of pipe (28), consists of heating assemblies (20, 24) each comprising at least one electrical induction coil (32, 36) wound on an annular, laminated, magnetic core assembly (30, 34). The lowermost surfaces of said core assembly (30, 34) define a saddle shape adapted to be seated on the exterior surface of said second length of pipe (28). The arrangement of the coils (32, 36) and the core assemblies (30, 34) is such that substantially all of the magnetic flux generated when the apparatus is seated on the pipe (28) and the coil is energised is contained within the core assembly and within the wall of the pipe (28). Advantageously, the core assemblies (30, 34) have E-sections profiles, the ends of the limbs of the E-sections comprising the lowermost surfaces of the core assemblies and the coils being wound about the central limbs of the E-sections.

Abstract: A system for transporting a pig (28) along the interior of a pipeline (26), particularly for the purpose of installing a liner (12) in the pipeline by towing the liner behind the pig, in which a hydrostatic head is applied on either side of the pig and the head on the downstream side of the pig is reduced such that the pig is transported along the interior of the pipeline by the resultant pressure differential. Where the system is employed in a pre-existing subsea pipeline, the hydrostatic heads may be applied by means of risers (14, 24) and the pressure differential created by means of a pump (30) adapted to pump water out of the downstream riser (24). The liner may be pulled through a flooded pipe by means of a pig, cable, self-propelled pipe crawler, or by combinations of these. A further cable may also be employed to apply a back tension, and/or to limit the pulling force applied to the liner and/or to enable the liner to be pulled backwards.

Abstract: A storage system for storing continuous lengths of rigid pipe, particularly for storage of pipe prior to the spooling of the pipe onto the pipe storage reel of a marine pipelay vessel. The system comprises a loop of rail track with a plurality of rail bogies arranged around the circumference of the loop. The bogies are adapted to retain and receive multiple turns of the length of pipe extending around the loop. The radius of curvature of the loop is selected such that the bending of the pipe around the loop does not result in plastic deformation of the pipe. Arrangements for loading and offloading the pipe may include: a pipe guide suspended from a gantry spanning the track and a pipe loading/offloading path; pipe tensioning means located downstream of the pipe guide in the offloading direction; and an "expansion arc" extending from the loading/offloading point to allow variations in the length of the pipeline path extending from the loop to a vessel mooring location.

Abstract: Means for securing a polymer liner to the inner surface of a pipe comprises an end piece consisting of a hub portion and a corrosion resistant metallic insert. The polymer hub is fusion welded to the end of the liner, and the metallic insert is seal welded portion of the inner surface of the pipe clad with corrosion resistant material at a distance from the outer end of the pipe. The clad portion may be provided by a pup piece welded to the end of the pipe. This arrangement allows two lengths of lined pipes to be joined by welding with a continuous corrosion resistant internal surface, without damage to the polymer pipe linings and in a manner which allows an assembled pipe string to be spooled onto a reel for subsequent pipelaying operations. In the preferred embodiment, the metal insert is screw-threaded to the polymer hub with an elastomeric seal therebetween, which provides a secondary seal between the end piece and the pipe wall.