Method and apparatus for fabricating an off-shore structure
AssigneeKaiser Steel Corporation
InventorsEero M. Hekkanen, Alpo J. Tokola
Life of this patent
Estimating the term…
Abstract
Improved method and apparatus for assembling and completing the fabrication of a multilegged structure of extended length at an offshore site wherein separate multilegged structural modules are selectively floated, disposed end-to-end, and aligned relative to each other at the offshore site such that the ends of aligned legs of the individual sections can be drawn and clamped together and then welded while in a clamped condition whereby the several welded-together sections can form an elongated unitary structure.
Claims35
The method of fabricating a modular offshore structure comprising the steps of transporting at least a pair of individual structural modules each of which is made up of interconnected and floatable watertight legs from an onshore site to a preselected offshore site, then while the said pair of modules are partially submerged in water at the offshore site selectively controlling the ballast in the watertight legs of each module of the pair of modules and maneuvering said pair of modules relative to each other until the legs of one module are fully aligned with the legs of the other and opposed module, progressively drawing said aligned legs of the pair of opposed modules together until they are abutted, and while holding the abutted legs of the modules firmly clamped together rigidly securing one leg of a pair of abutted legs to the other leg of said pair of legs.
A collapsible and floatable cofferdam device for engaging and isolating a pair of abutted legs on adjacent modular platform sections in the area of the joint between the pair of legs from the surrounding water at an offshore site, said device comprising a plurality of generally channel-shaped and interconnected elements, opposed edges of adjoining web portions of adjacent elements of the plurality of elements being hingedly interconnected together so as to effect opening and closing of the plurality of elements from an extended condition to a collapsed condition and vice versa, the opposed side edges of adjoining flange portions of adjacent elements being adapted to be separated from each other in order to define a groove therebetween when adjacent elements of the plurality of elements are in an extended condition, said opposed side edges at the adjoining flange portions of said elements being adapted to be disposed in abutting and sealing engagement with each other and the platform sections upon adjacent elements of the plurality of elements being in a collapsed condition, and pontoon means connected to certain of said elements for controlling the overall buoyancy of the plurality of elements during flotation and collapse of the plurality of elements about the pair of abutted legs at an offshore site.
A cofferdam element for a collapsible and floatable cofferdam device used for isolating from the surrounding water at an offshore site a pair of abutted legs of adjacent modular platform sections in the area of the joint between abutted legs, said cofferdam element comprising a web portion having first, second, third and fourth web edges, said first and third web edges and said second and fourth web edges, respectively, being in opposed relationship to one another, first and second hinge means located separately along said first and third web edges for hingedly connecting said cofferdam element with a pair of flanking cofferdam elements, first and second upstanding flange portions attached in watertight relationship to said web portion along said second and fourth web edges, each of said flange portions comprising a first and second flange edge each originating respectively at said first and third web edges and terminating at a top edge of each of said upstanding flange portions, at least a portion of each of said top edges being configured to closely conform with the cross-sectional configuration of at least a portion of the underside of the legs of the tower section, web edge sealing means positioned along said first and third web edges to sealingly engage with web edges of said flanking cofferdam elements, flange edge sealing means positioned along said flange edges to sealingly engage with flange edges of said flanking cofferdam elements, and top edge sealing means positioned at said top edge to sealingly engage with the outer surface of said tower leg.
A cofferdam element for a collapsible and floatable cofferdam device used for isolating from the surrounding water at an offshore site a pair of abutted legs of adjacent modular platform sections in the area of the joint between abutted legs, said cofferdam element comprising a web portion having first, second, third and fourth web edges, said first and third web edges and said second and fourth web edges, respectively, being in opposed relationship to one another, hinge means located along said first web edge for hingedly connecting said cofferdam element with another flanking cofferdam element, first and second upstanding flange portions attached in watertight relationship to said web portion along said second and fourth web edges, each of said flange portions comprising a first flange edge originating at said first web edge and terminating at a top edge of each of said upstanding flange portions, at least a portion of each of said top edges being configured to closely conform with the cross-sectional configuration of at least a portion of the side of the legs of the tower section, each of said flange portions further comprising a second flange edge originating at said third web edge and extending substantially perpendicularly to said web portion and terminating at said top edge, web edge sealing means positioned along said first and third web edges to sealingly engage with web edges of said flanking cofferdam elements, flange edge sealing means positioned along said first flange edges to sealingly engage with flange edges of said flanking cofferdam element, and top edge sealing means positioned at said top edge to sealingly engage with the outer surface of said tower leg.
A floatable module which is floatable to an offshore assembly site in horizontal orientation to be attached while horizontal to at least one other said module and then upturned to vertical orientation and emplaced, each said module comprising a series of laterally spaced floatable watertight leg elements and a plurality of brace elements interposed therebetween and interconnected to the series of spaced leg elements to form a module of polyhedral configuration, guiding and aligning means adapted to facilitate the abutting and joining of the ends of said leg elements of adjacent of said modules while said leg elements are horizontally oriented and floating in the water, said guiding and aligning means comprising a plurality of guide strip elements spaced about the outer peripheral portion of at least one of said leg elements at the end thereof, said guide strip elements extending outwardly beyond said leg end generally horizontally to receive therebetween the leg end of an adjacent of said modules to be brought into abutting relationship therewith, said guide strip elements being of such length as to guide and align the leg end of the adjacent leg elements during at least the final portion of movement of said leg end into abutting relationship, and an upstanding lug attached near the end of a leg in opposed relationship to a leg on an adjacent one of said modules to facilitate the attachment of a clamping device between said legs when the adjacent ends of the legs are drawn into abutment to form an extended structure.
A floatable module which is floatable to an offshore assembly site in horizontal orientation to be attached while horizontal to at least one other said module and then upturned to vertical orientation and emplaced, each said module comprising a series of laterally spaced floatable watertight leg elements and a plurality of brace elements interposed therebetween and interconnected to the series of spaced leg elements to form a module of polyhedral configuration, guiding and aligning means adapted to facilitate the abutting and joining of the ends of said leg elements of adjacent of said modules while said leg elements are horizontally oriented and floating in the water, and attachment means on said module for permitting attachment of means for pulling together adjacent of said modules from positions spaced from one another to a position wherein said leg elements are substantially in abutting relationship with one another.
A floatable module which is floatable to an offshore assembly site in horizontal orientation to be attached while horizontal to at least one other said module and then upturned to vertical orientation and emplaced, each said module comprising a series of laterally spaced floatable watertight leg elements and a plurality of brace elements interposed therebetween and interconnected to the series of spaced leg elements to form a module of polyhedral configuration, guiding and aligning means adapted to facilitate the abutting and joining of the ends of said leg elements of adjacent of said modules while said leg elements are horizontally oriented and floating in the water, and means to move adjacent of said modules, while the leg elements are in horizontally oriented position, from positions spaced from one another to a position wherein the leg elements are substantially in abutting relationship with one another.
Dependencies are inferred from the claim text.