Importance

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Abstract

When laying pipe from a pipelay vessel into the sea, the pipe is subject to torsion. To relieve this torsion an apparatus to perform controlled relative rotation between the pipe and the vessel is proposed, which apparatus is also able to permit the pipelay vessel to 'weather vane' about the pipe without twisting it. The apparatus comprises a hold off clamp (3) which is mounted within a housing (5) via thrust bearings (4). The housing (5) is mounted to the vessel (6), and the clamping means (3) is clamped to the pipe (1). A brake assembly (12) and a drive means (13) capable of providing predetermined rotation and torsional damping, enable controlled relative rotation of the clamping means within the housing. With the pipe secured in the clamping means controlled relative rotation can be achieved for torsion relief, or weather vaning of the pipelay vessel about the pipe can be achieved.

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First Claim