US 5,662,434 AGranted

Method and apparatus for the offshore installation of multi-ton prefabricated deck packages on partially submerged offshore jacket foundations

OwnerJon E. Khachaturianinventor

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Abstract

A method and apparatus for the installation or removal 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. End caps are removably connected to each of a two diagonally extending, longitudinal members of a boom portion of the truss assembly. Upper and lower connections form attachments between the end caps and the deck package at the upper elevational positions on the deck package. Tensile connections form attachments between the deck package and barge at a lower elevational position. 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.

Claims17

Dependent claims

A lifting apparatus for placing a multi-ton deck package on an offshore jacket or partially submerged foundation, comprising:

a) a pair of barges, each defining a base that can support a large multi-ton load;
b) truss means supported by the barges about the periphery of the deck package for forming a load transfer between the barges and the deck package to be placed, said truss means including a plurality of diagonally extending lift booms, each lift boom having a lower end attached to a barge and an upper end which enables attachment to the deck package;
c) each boom comprising:
i) a pair of longitudinally extending members;
ii) a plurality of end caps that each removably connect to at least one longitudinally extending lift boom;
iii) the end caps forming part of the connection between the deck package and a barge;
d) upper and lower connection means for forming attachments of the truss means to the deck package at upper and lower respective elevational positions;
e) said upper and lower connection means including corresponding connecting portions that enable the barges and package to quick disconnect, one of said corresponding quick connecting portions including the upper end portion of the lifting boom, said other quick connecting portion being positioned at said upper elevational position;
and
f) means for lowering the combination of the truss means and the supported deck package with respect to the jacket or partially submerged foundation during placement of the deck package on the jacket or partially submerged foundation.

7 more elements

A method for the offshore installation of a multi-ton prefabricated deck package on a jacket or partially submerged foundation, comprising the steps of:

a) transporting the prefabricated deck package to the site of the jacket or partially submerged foundation on a transport barge;
b) attaching a triangular truss-like lifting assembly to the deck package at multiple elevational positions on the deck package including positions 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 installation which has a variable length and a diagonally extending chord normally in compression during the lifting process;
c) wherein in step "b" the truss like lifting assembly has a plurality of removable end caps that attach to ends of the diagonally extending chord member and quick connect fittings are used to attach the diagonally extending chords to the deck package and to the end caps;
d) structurally supporting the triangular truss-like lifting assembly with one or more lift barges;
e) removing the transport barge as a support for the deck package so that the deck package is supported by the triangular truss-like lifting assembly and lift barges, with the deck package forming a load carrying portion of the triangular truss-like lifting assembly;
f) aligning the deck package with the jacket or partially submerged foundation so that the deck package can be placed on the jacket or partially submerged foundation;
and
g) lowering the deck package upon the jacket or partially submerged foundation by changing the length of the horizontal chord of each triangular truss like lifting assembly.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/615,838Filed 14 Mar 1996 · continuation in part
Priority: 15 Mar 1995
Granted: 2 Sep 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

E02B 17/00
Artificial islands mounted on piles or like supports
B63B 27/16
Arrangement of ship-based loading or unloading equipment for cargo or passengers: of lifts or hoists
B63B 35/003
Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for: for transporting very large loads,…
B63B 77/00
Transporting or installing offshore structures on site using buoyancy forces