Patent ID: 6981823
Filing Date: 2006-01-03
Classification: E02B

Abstract:
1. A method for installation of a deck structure at an offshore location, where the deck structure is put on a vessel at a location inshore, then transported on the vessel to the offshore location and positioned relative to legs ( 13 ) of a jacket or gravity base type support structure standing on the sea bottom, or the legs or columns of a floating substructure, the deck structure having deck legs ( 5 ) corresponding to support legs ( 13 ) on the support structure, the deck legs ( 5 ) each being provided with a jack type of mechanism with an associated piston ( 1 ) which is extended into contact with and supported by the top part ( 3 ) of the corresponding support leg ( 13 ) at the beginning of a procedure for transferring the weight of the deck structure from the vessel to the support legs ( 13 ), said procedure comprising ballasting the vessel ( 12 ) while permitting wave induced motions of the vessel ( 12 ) to further lift the deck structure with respect to the support structure and permitting the pistons ( 1 ) to extend further below the respective deck legs ( 5 ) when a higher wave is encountered, but preventing the pistons ( 1 ) from moving into the respective deck legs ( 5 ) upon receding wave motion, continuing ballasting at least until the entire weight of the deck structure has been transferred to the support structure in order for the vessel ( 12 ) to clear the deck structure and permit removal of the vessel ( 12 ) with respect to the support legs ( 13 ), and lowering the deck structure to bring the deck legs ( 5 ) and the corresponding support legs ( 13 ) together to permit welding of the deck structure and support structure together, wherein the pistons ( 1 ) are prevented from moving into the respective deck legs ( 5 ) during the weight transfer by mechanically locking the pistons ( 1 ) in the legs by means of a one-way ratchet type mechanism.