Ships – Mooring device
Reexamination Certificate
2002-04-09
2003-07-08
Avila, Stephen (Department: 3617)
Ships
Mooring device
C441S005000
Reexamination Certificate
active
06588357
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to mooring systems and in particular to turret mooring systems. Still more particularly, the invention relates to a coupling or mounting arrangement for coupling an upper turret structure to a lower turret of a Floating Production, Storage and Offloading vessel (FPSO) or the like.
2. Description of the Prior Art
The prior art has provided mooring systems with turret structures having upper and lower portions which are rigidly coupled together. For example, in U.S. Pat. No. 5,316,509, an upper turret structure
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, on which a product swivel and manifold decks are placed, is rigidly secured to the top of the lower turret structure which is rotatably supported in a moonpool of the vessel by upper and lower bearing assemblies.
Other prior art patents have provided flexible bearing structures for rotatably supporting the lower turret structure. U.S. Pat. Nos. 4,955,310 and 5,515,804 are examples of flexible bearing supports. Other arrangements provide axial and radial springs to support the turret from the vessel.
3. Identification of Objects of the Invention
A primary object of this invention is to provide an improved turret arrangement for a vessel mooring system which reduces the cost and complexity of large diameter turret arrangements where several flexible fluid conduits are supported and housed within the turret.
Another object of the invention is to eliminate springs which have been used around the outside diameter of the turret bearing in the past.
SUMMARY OF THE INVENTION
The objects identified above, as well as other advantages and features are incorporated in an improved turret, which includes an upper turret structure characterized by an upper turret diameter, a lower turret structure characterized by a lower turret diameter which is larger than the upper turret diameter, and a flex joint arrangement between the upper and lower turret structures.
The upper turret structure is coupled to an upper portion of the vessel's moonpool wall by an upper axial/radial turret bearing assembly and a plurality of tubes which angle inwardly from the moonpool wall to a rigid-box ring on which the bearing assembly is mounted. The tubes are arrayed in a conical pattern and function not only to allow smaller diameter bearings to be used on the upper turret, but also isolate the upper axial/radial turret bearing assembly from ovaling of the vessel. The lower turret structure is coupled to a lower portion of the moonpool wall by a lower radial bearing assembly. A flex joint arrangement, which includes a middle ring, couples the upper turret structure to the lower turret structure while minimizing moments acting on the upper axial/radial turret bearing via a flex joint. Several embodiments of the flex joint arrangement are provided. In one embodiment, the flex joint is located at an upper ring of the upper turret structure. In another embodiment, the flex joint is located at the middle ring of the flex joint arrangement.
REFERENCES:
patent: 4490121 (1984-12-01), Coppens et al.
patent: 4637335 (1987-01-01), Pollack
patent: 4955310 (1990-09-01), Pollack
patent: 5336020 (1994-08-01), Askestad
patent: 5468166 (1995-11-01), Breivik et al.
patent: 5515804 (1996-05-01), Pollack
patent: 5517937 (1996-05-01), Lunde
patent: 5782197 (1998-07-01), Pollack
patent: 5823837 (1998-10-01), Boatman et al.
patent: 5893334 (1999-04-01), Poranski
patent: 5957076 (1999-09-01), Pollack et al.
Andrews & Kurth
Avila Stephen
Bush Gary
FMC Technologies Inc.
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