Abstract: A support elelment (12) for supporting a rigid pipeline (10) during plastic bending of the pipeline has a transverse cross-sectional configuration such that, in use, a pipeline supported by the support element contacts said support element is at least first and second points (14, 16) disposed substantially symmetrically on either side of the plane of bending, the points of contact being arranged such that resultant forces between the pipeline and the support element act at points which are disposed substantially symmetrically about the plane of bending and which are spaced apart by an angle a greater than 90.degree. and less than 180.degree. around the cross-sectional circumference of the pipeline. The angle a is selected so as to minimize ovalisation for a pipeline of given material, diameter and wall thickness, and for a given bend radius and pipeline tension, or to provide useful modification of ovalisation over ranges of these parameters.

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: 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.