Gimbaled table riser support system

Abstract

For a spar type floating platform having risers passing vertically through the center well of a spar hull, there is provided apparatus for supporting the risers from a gimbaled table supported above the top of the spar hull. The table flexibly is supported by a plurality of non-linear springs attached to the top of the spar hull. The non-linear springs compliantly constrain the table rotationally so that the table is allowed a limited degree of rotational movement with respect to the spar hull in response to wind and current induced environmental loads. Larger capacity non-linear springs are located near the center of the table for supporting the majority of the riser tension, and smaller capacity non-linear springs are located near the perimeter of the table for controlling the rotational stiffness of the table. The riser support table comprises a grid of interconnected beams having openings therebetween through which the risers pass. The non-linear springs may take the form of elastomeric load pads or hydraulic cylinders, or a combination of both. The upper ends of the risers are supported from the table by riser tensioning hydraulic cylinders that may be individually actuated to adjust the tension in and length of the risers. Elastomeric flex units or ball-in-socket devices are disposed between the riser tensioning hydraulic cylinders and the table to permit rotational movement between the each riser and the table.

Dependencies are inferred from the claim text.