Method and apparatus for the offshore installation of multi-ton prefabricated deck packages on partially submerged offshore jacket foundations
First Claim
1. A method for the offshore installation of multi-ton prefabricated deck package on a jacket foundation, comprising the steps of:
- a. transporting the prefabricated deck package to the site of the jacket base on a first transport barge;
b. attaching a triangular truss-like lifting assembly to the deck package at multiple positions on the deck package that are at least on generally opposite sides of the deck package, and at upper and lower positions on the deck package respectively and at vertices of the triangular truss-like lifting assembly, the triangular truss-like lifting assembly including at least three chords, including a horizontal chord normally in tension during the lifting process which has a variable length and a diagonally extending chord normally in compression during the lifting process;
c. structurally supporting the triangular truss-like lifting assembly with one or more lift barges;
d. removing the transport barge as a support for the deck package so that the deck is supported by the triangular truss-like lifting assembly and lift barges, with the deck package froming a load carrying portion of the triangular truss-like lifting assembly;
e. alinging the deck package with the jacket so that the deck package can be placed on the jacket; and
f. lowering the deck package upon the jacket by changing the length of the horizontal chord of each triangular truss-like lifting assembly.
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Accused Products
Abstract
A method and apparatus for the installation of large multi-ton prefabricated deck packages includes the use of usually two barges defining a base that can support a large multi-ton load. A variable dimensional truss assembly is supported by the barge and forms a load transfer interface between the barge and the deck package. Upper and lower connections form attachments between the truss members and the deck package at upper and lower elevational positions on the deck package. The variable dimension truss includes at least one member of variable length, in the preferred embodiment being a winch powered cable that can be extended and retracted by winding and unwinding the winch. Alternate embodiments include the use of a hydraulic cylinder as an example.
70 Citations
23 Claims
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1. A method for the offshore installation of multi-ton prefabricated deck package on a jacket foundation, comprising the steps of:
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a. transporting the prefabricated deck package to the site of the jacket base on a first transport barge; b. attaching a triangular truss-like lifting assembly to the deck package at multiple positions on the deck package that are at least on generally opposite sides of the deck package, and at upper and lower positions on the deck package respectively and at vertices of the triangular truss-like lifting assembly, the triangular truss-like lifting assembly including at least three chords, including a horizontal chord normally in tension during the lifting process which has a variable length and a diagonally extending chord normally in compression during the lifting process; c. structurally supporting the triangular truss-like lifting assembly with one or more lift barges; d. removing the transport barge as a support for the deck package so that the deck is supported by the triangular truss-like lifting assembly and lift barges, with the deck package froming a load carrying portion of the triangular truss-like lifting assembly; e. alinging the deck package with the jacket so that the deck package can be placed on the jacket; and f. lowering the deck package upon the jacket by changing the length of the horizontal chord of each triangular truss-like lifting assembly. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 13, 14)
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10. A lifting apparatus for placing a multi-ton deck package on an offshore jacket foundation, comprising:
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a. barge means defining a base that can support a large multi-ton load; b. truss means supported by the barge means about the periphery of the deck package for forming a load transfer between the barge means and the deck package to be placed; c. upper and lower connection means for forming attachments of the truss means to the deck package at upper and lower respective elevational positions; and d. means for lowering the combination of the truss means and the supported deck package with respect to the jacket foundation such as during placement of the deck package on the jacket foundation. - View Dependent Claims (11, 12, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification