Marine pipelay system and method

A marine pipe laying system for vertical or near vertical laying of an offshore pipeline, wherein the system comprises:

• a. a main supporting structure;
• b. a pivotable structure supported pivotably by the main supporting structure;
• c. a pipe connecting station, wherein a pipe section is connected to an uppennost end of a previously launched pipeline,
• d. a static clamp positioned above a mobile clamp adapted for releasably securing the uppermost end of the previously launched pipeline, wherein the static clamp is adapted to support the weight of the previously launched pipeline, and the static clamp is located below the pipe connecting station;
• e. the mobile clamp positioned below the static clamp adapted for releasably securing the previously launched pipeline at a position essentially below the static clamp, wherein the mobile clamp is adapted to support the weight of the offshore pipeline as the offshore pipeline is released from the static clamp;
• f. a mobile clamp hoist comprising a mobile clamp cable connected to the mobile clamp, wherein the mobile clamp hoist is adapted to raise and lower the mobile clamp and the offshore pipeline supported thereby, wherein the path of the mobile clamp cable intersects the pivot axis of the pivotable structure;
• wherein the offshore pipeline is raised and lowered by releasing the static clamp and engaging the mobile clamp, at which point the mobile clamp cable raises or lowers the mobile clamp which is engaged to the offshore pipeline;
• and
• wherein the offshore pipeline is engaged by the mobile clamp in a clamping position while the offshore pipeline is supported by the static clamp, whereafter the static clamp is released, whereafter the mobile clamp and the offshore pipeline are raised from the clamping position to a raised connecting position, wherein the pipe section is connected to the uppermost end of the previously launched pipeline, whereafter the mobile clamp and the offshore pipeline are lowered to a lower position below the clamping position, wherein at the lower position the static clamp secures the offshore pipeline, and whereafter the mobile clamp is released from the offshore pipeline and the mobile clamp is raised back to the clamping position, wherein the clamping position is still below that of the static clamp.

A marine pipelaying system for vertical or near vertical laying of an offshore pipeline, wherein the system comprises:

• a. a main supporting structure to be mounted on a vessel;
• b. a pivotable structure supported pivotably by the main support structure;
• c. a pipe connecting station, wherein a pipe section is connected to an uppermost end of a previously launched pipeline;
• d. a static clamp positioned above a mobile clamp adapted for releasably securing the uppermost end of the previously launched pipeline, wherein the static clamp is adapted to support the weight of the previously launched pipeline, and the static clamp is located below the pipe connecting station and the static clamp is arranged on the pivotable structure;
• e. the mobile clamp positioned below the static clamp adapted for releasably securing the previously launched pipeline, wherein the mobile clamp is adapted to support the weight of the offshore pipeline as the offshore pipeline is released from the static clamp;
• f. wherein the offshore pipeline is raised and lowered by releasing the static clamp and engaging the mobile clamp, at which point the mobile clamp hoist raises or lowers the mobile clamp which is engaged to the offshore pipeline, wherein the path of the mobile clamp cable intersects the pivot axis of the pivotable structure;
• and
• g. the pivotable structure freely pivots about at least one pivot axis by the main supporting structure, wherein the static clamp is arranged on the pivotable structure such that the pivotable structure comprises an orientation essentially independent from sea-state induced vessel motions.

A marine pipelaying system for vertical or near vertical laying of an offshore pipeline, wherein the system comprises:

• a. a main supporting structure;
• b. a pivotable structure supported pivotably by the main support structure;
• c. a pipe connecting station, wherein a pipe section is connected to an uppermost end of a previously launched pipeline;
• d. a static clamp positioned above a mobile clamp adapted for releasably securing the uppermost end of the previously launched pipeline, wherein the static clamp is adapted to support the weight of the previously launched pipeline, and the static clamp is located below the pipe connecting station and the static clamp is arranged on the pivotable structure;
• e. the mobile clamp positioned below the static clamp adapted for releasably securing the previously launched pipeline, wherein the mobile clamp is adapted to support the weight of the offshore pipeline as the offshore pipeline is released from the static clamp;
• wherein the offshore pipeline is raised and lowered by releasing the static clamp and engaging the mobile clamp, at which point the mobile clamp cable raises or lowers the mobile clamp which is engaged to the offshore pipeline;
• f. and
• g. at least one hydraulic actuator engaging the pivotable structure for maintaining an orientation of the pivotable structure.

A marine pipelaying system for vertical or near vertical laying of an offshore pipeline, wherein the system comprises:

• a. a main supporting structure;
• b. a pivotable structure supported pivotably by the main support structure;
• c. a pipe connecting station, wherein a pipe section is connected to an uppermost end of a previously launched pipeline;
• d. a static clamp positioned above a mobile clamp adapted for releasably securing the uppermost end of the previously launched pipeline, wherein the static clamp is adapted to support the weight of the previously launched pipeline, and the static clamp is located below the pipe connecting station;
• e. the mobile clamp positioned below the static clamp adapted for releasably securing the previously launched pipeline, wherein the mobile clamp is adapted to support the weight of the offshore pipeline as the offshore pipeline is released from the static clamp;
• wherein the offshore pipeline is raised and lowered by releasing the static clamp and engaging the mobile clamp, at which point the mobile clamp cable raises or lowers the mobile clamp which is engaged to the offshore pipeline;
• and
• f.
• wherein the main supporting structure comprises at least two movable support members extending at opposite sides of the pivotable structure, wherein the pivotable structure is connected to each movable support member through pivot connections adapted to allow the pivotable structure to pivot about a pivot axis with respect to the main supporting structure, and wherein the movable support members move the pivot connections essentially in a vertical direction so as to set a desired inclination of the pivot axis with respect to horizontal.