Abstract: A fluid vent (26) for venting fluid from the annulus between the inner surface of a rigid conduit (20) and the outer surface of a conduit liner (10). The fluid vent (26) consists of a length of rigid conduit (34) containing a multiplicity of apertures (32) extending through the wall of the conduit and arranged in an annular pattern around the circumference of conduit (34). The fluid vent (26) further comprises means defining a closed annular volume (36) extending around the exterior circumference of the conduit (34) and interconnecting the outer ends of the apertures (32) with at least one fluid outlet passage (40) located on the exterior of the conduit (34) and communicating with said annular volume (36). The fluid vent can be used to expel water or other liquids from the annular space when retro-fitting a liner to a conduit, venting gas which has permeated through the lining into the annulus, or for assisting in the movement of fluid through the annulus.

Abstract: A marine riser, particularly but not exclusively for use in connecting a subsea well installation to a dynamically positioned servicing vessel, comprises at least one section formed from rigid pipe and at least one section formed from flexible pipe. Preferably, the upper and lower sections (10, 12) are formed from fixed lengths of flexible pipe and the central section is formed from a plurality of lengths of rigid pipe which may be assembled to make up any required length. The riser may be deployed from a moonpool of the vessel and serves to accommodate movements of the vessel on the surface. This allows the use of a dynamically positioned service vessel rather than a conventional drilling rig.

Abstract: A marine pipelay vessel equipped with a pipe laying apparatus comprising a pipe handler for moving the pipe into its raised launching position, a pipe connection station for connecting together pipe ends when in the launching position, a pipe support for maintaining the pipe in a raised position, a static clamp for releasably securing the upper end of a previously launched pipe, a pipe launcher for controllably launching the raised pipe stalk in which the pipe launcher comprises a second mobile clamp adapted to be releasably secured to the pipe such that the second clamp may be raised and lowered controllably over a predetermined stroke distance between the uppermost and the lowermost stroke position relative to the vessel.

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: Mooring apparatus and method of use thereof, for marine vessels, comprising a subsea anchor (12) such as a suction pile (14A), and including a swivel (16) to which at least one mooring line (24) is connected, the other end of the mooring line being adapted for connection to the bow mooring apparatus of a marine vessel (22) such as a conventional tanker. The mooring line (24) includes a load cell for measuring tension applied to the line by reverse thrust of the vessel. Signals from the load cell are transmitted from the bow of the vessel to the bridge (40), enabling manual, automatic or semi-automatic control of the applied tension. In use, the mooring line is maintained under tension such that the vessel may weathervane around the swivel.

Abstract: A reel pipelaying vessel of the type having a main pipeline reel (118) mounted for rotation about a horizontal axis, a variable angle pipeline launching ramp (128) having pipeline straightening and tensioning means mounted thereon and having: an improved pipeline launching ramp arrangement including rack and pinion elevator means (140, 142, 144); an improved level winding mechanism for translating the pipeline straightening and tensioning means as the pipe is spooled onto or unspooled from the reel; sea fastening means for restraining axial movement of the reel while the vessel is in transit, thereby increasing the maximum pipeline load for reel bearings (114, 116) of a given load capacity; sponsons (108, 110) for providing additional flotation and strengthening the hull; an improved arrangement of auxiliary reels (120); a cantilever structure (200) for guiding auxiliary lines, providing access to the main reel and protecting the bridge (218) of the vessel; improved pipeline abandonment and recovery arrangeme

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.

Abstract: An apparatus for laying marine pipelines of the type in which the pipeline is assembled along a horizontal axis on board a pipelaying vessel prior to being launched therefrom; in which the pipeline is plastically bent to a desired launch angle and, in most cases, at least partially straightened thereafter. In preferred embodiments, the pipeline is bent through an angle greater than 90.degree.. In the most preferred embodiments, the pipeline is diverted through an angle of substantially 270.degree., plus or minus an angle allowing variation in the launch angle from the vertical, and crosses itself prior to entering the water. The pipeline (102) is diverted by being passed around a wheel-like diverter structure (104), the pipeline being assembled in multiple fabrication lines to produce stalks which are aligned and connected in a central firing line prior to being fed around the diverter structure. Other variations are also described.

Abstract: Method and apparatus for preventing the buckling of a pipeline (10) on either side of a localised zone of increased stiffness in the pipeline (such as a buckle arrester (12)) when the pipeline is bent around an arcuate path, in which packing elements (14) are located between the pipeline and a pipeline bearing surface (20) defining the arcuate pipeline path on either side of the zone of increased stiffness so as to vary the radius of curvature of the pipeline between a first, greatest value adjacent the zone of increased stiffness, and a second smaller value substantially equal to the radius of curvature of the arcuate pipeline path at a predetermined distance from the zone of increased stiffness on either side thereof. The packing elements (14) comprise a graded series of blocks adapted to be attached to the pipeline on either side of the zone of increased thickness. The blocks may be shaped as required to cooperate with the pipeline and the pipeline bearing surface.

Abstract: Methods and apparatus for laying marine pipelines of the type in which the pipeline is assembled along a horizontal axis on board a pipe laying vessel prior to being launched therefrom; in which the pipeline is plastically bent to a desired launch angle and, in most cases, at least partially straightened thereafter. In preferred embodiments, the pipeline is bent through an angle greater than 90.degree.. In the most preferred embodiments, the pipeline is diverted, initially upwardly, through an angle of substantially 180.degree. sheave (28), prior to being bent downwards to the desired launch angle by an adjustable angle ramp (30). Other variations are also described.

Abstract: A reel pipelay vessel is used to lay a first pipeline (6) and a second pipeline (7) subsequently. The second pipeline (7) is spooled on top of the first pipeline (6) at a shore base by use of transition joint (11) secured to the trailing end of the first pipeline (6) and to the leading end of the second pipeline (7). A variety of transition joints are described. In each case, the bending characteristic of the transition joint is selected to avoid buckling during spooling of the pipe transition. In an alternative embodiment the transition joint comprises a first pipe section (21) of first diameter hingeably connected to a second pipe section (22) of second diameter, the first and second pipe sections being bent to a common radius corresponding to the radius of curvature of the first pipe when spooled onto a reel.

Abstract: A reel pipelaying vessel includes pipe conditioning apparatus at its stern. The pipe conditioning apparatus includes a radius control device for imparting a substantially uniform curve to the pipe after it is unspooled from the reel, straightening apparatus for imparting a reverse bending force to the pipe opposite to the curvature imparted to the pipe by the reel, and apparatus for guiding the pipe into the water after it emerges from the straightening apparatus. The pipe conditioning apparatus is pivotable about a pivot axis to adjust the pipe entry angle at which the pipe enters the water. A stinger assembly is located at the downstream end of the pipe conditioning apparatus, extending sternwards of the vessel, and arranged to further increase the entry angle of the pipe after it exits the pipe conditioning apparatus. The stinger is curved and is provided with a series of pipe supporting rollers or pipe supporting endless conveyors apparatus.

Abstract: A reel pipelaying vessel includes pipe conditioning apparatus located at its stern. The pipe conditioning apparatus includes radius control apparatus for imparting a substantially uniform curve to the pipe after it is unspooled from the reel, straightening apparatus for imparting a reverse bending force to the pipe opposite to the curvature imparted to the pipe by the reel, and an apparatus for guiding the pipe into the water after it emerges from the straightening apparatus. The pipe conditioning apparatus is pivotable about a pivot axis to adjust the pipe entry angle at which the pipe enters the water. Endless pipe conveyor apparatus is arranged around the radius control apparatus to convey the pipe over the radius control apparatus in the passage of the pipe from the reel into the pipe straightening apparatus. The position of the downstream end of the radius control apparatus is adjustable relative to the pipe straightening apparatus.