U.S. patent application number 09/756499 was filed with the patent office on 2001-10-18 for mooring tube assembly with swivel mounted chain support.
This patent application is currently assigned to FMC CORPORATION. Invention is credited to Fontenot, William L., Han, Humphrey C., Krafft, Martin J., Seaman, David M..
Application Number | 20010029878 09/756499 |
Document ID | / |
Family ID | 22639095 |
Filed Date | 2001-10-18 |
United States Patent
Application |
20010029878 |
Kind Code |
A1 |
Seaman, David M. ; et
al. |
October 18, 2001 |
Mooring tube assembly with swivel mounted chain support
Abstract
A vessel with a mooring tube assembly with swivel mounted chain
supports. The assembly includes a frame arranged and designed for
support within a vertical opening of the vessel at its bow and/or
its stem. A plurality of chain tubes are carried on the outer side
of the frame in an arc such that their top ends extend upwardly
generally parallel to the vertical axis of opening of the vessel.
The vessel includes a deck mounted above the upper end of the
frame. A track on the deck allows a single winch to be moved so
that a pull-in line can be registered with any of the top ends of
the tubes. A plurality of chain supports are rotationally mounted
on the frame where each chain support has an outlet and an inlet. A
trunnion chain stopper is provided between the outlet and inlet of
the chain support. The outlet of each chain stopper is in
registration with the lower end of one of the chain tubes.
Inventors: |
Seaman, David M.; (Hockley,
TX) ; Han, Humphrey C.; (Houston, TX) ;
Krafft, Martin J.; (Houston, TX) ; Fontenot, William
L.; (Houston, TX) |
Correspondence
Address: |
GARY L. BUSH
MAYOR, DAY, CALDWELL & KEETON, L.L.P.
SUITE 1900
700 LOUISIANA
HOUSTON
TX
77002
US
|
Assignee: |
FMC CORPORATION
|
Family ID: |
22639095 |
Appl. No.: |
09/756499 |
Filed: |
January 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60175144 |
Jan 7, 2000 |
|
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|
Current U.S.
Class: |
114/230.12 |
Current CPC
Class: |
B63B 21/50 20130101;
B63B 21/507 20130101 |
Class at
Publication: |
114/230.12 |
International
Class: |
B63B 021/00 |
Claims
What is claimed is:
1. In a vessel including a vertical passage which extends from a
hull to a top deck including a plurality of anchor chains extending
through said vertical passage, said vertical passage having a
generally vertical axis, an improvement comprising, a structure
(50) (51) arranged and designed to be installed and supported
within said vertical passage (53), said structure (50) (51)
including a support frame (58) (55) and a plurality of tubes (52)
(57) placed in a tube arrangement about a periphery of said support
frame, said tubes being arranged and designed for anchor chains to
pass through, said tubes having top ends which are generally
parallel to said vertical axis of said vertical passage.
2. The vessel of claim 1 further comprising, a deck (99) (100)
mounted on said vessel above an upper end of said support frame
(51) (55), a track (60) (82) disposed on said deck, said track
placed in a track arrangement which corresponds to said tube
arrangement, and a winch (79) (81) mounted on said deck and
arranged and designed to move along said track (60) (82) so that a
pull-in line can be generally registered with any of said top ends
of said tubes (52) (57), whereby a single winch (79) (81) can pull
in any one of a plurality of anchor chains disposed in said tubes
(52) (57).
3. The vessel of claim 1 further comprising, a plurality of chain
supports (56), each chain support (56) being rotationally mounted
on said support frame (51) (55), each chain support having a chain
outlet (47) which is in registration with one of said plurality of
tubes, with each chain support having an inlet (84).
4. The vessel of claim 3 wherein each chain support (56) includes,
a trunnion support body (40) arranged and designed for rotation
about a support body vertical axis, said support body having a
hollow upper shaft (47) serving as said chain outlet, said support
body vertical axis being parallel to said vertical axis of said
vertical passage, bearing blocks (37) mounted transversely to said
vertical axis in said support body, a trunnion chain stopper
housing (80) carried by said bearing blocks (37) and arranged and
designed for rotation with respect to said support body (40) about
an axis transverse to said vertical axis, a chain stopper (82)
carried within said housing (80), said chain stopper having an
outlet which communicates with said hollow upper shaft (47) for the
passage of a chain, said chain stopper having an inlet, and a chain
tube (84) coupled to said inlet of said chain stopper housing
(80).
5. The vessel of claim 1 wherein said structure (50) is mounted in
said vertical passage located at a stem of the vessel.
6. The vessel of claim 1 wherein said structure (51) is mounted in
said vertical passage located at a bow of the vessel.
7. A chain support for a vessel comprising a trunnion support body
arranged and designed for rotation about a first axis, bearing
blocks mounted transversely to said first axis in said support
body, a trunnion chain stopper housing carried by said bearing
blocks and arranged and designed for rotation with respect to said
support body about a second axis chain stopper which is transverse
to said first axis, a chain stopper carried within said chain
stopper housing, said chain stopper having an outlet for the
passage of a chain, said chain stopper having an inlet, and a chain
tube coupled to said inlet of said chain stopper housing.
8. The chain support of claim 7 wherein said first axis is a
vertical axis and said second axis is a horizontal axis.
9. The chain support of claim 7 wherein said first axis is a first
horizontal axis and said second axis is a second horizontal
axis.
10. The chain support of claim 8 wherein said support body has a
hollow upper shaft, and said outlet of said chain stopper
communicates with said hollow upper shaft for the passage of a
chain.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This non-provisional application claims priority from
provisional application 60/175,144 filed on Jan. 7, 2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates in general to mooring equipment for
vessels and in particular to chain support equipment for mooring
legs of a spread mooring arrangement for a permanently moored
storage vessel.
[0004] 2. Description of the Prior Art
[0005] FIGS. 1 and 2 illustrate a prior art spread mooring system
of British Patent 1,194,371 (published Jun. 10, 1970) having
mooring legs 10 at the bow and stern of the vessel 20. FIG. 1 is a
plan view of a storage vessel with two shuttle oil-tankers 22
berthed along side of it. FIG. 2 is a view similar to that of FIG.
1, but showing the storage vessel alone, skewed to port so that it
can be pointed toward wind, waves, or current. The mooring legs
must be lengthened and shortened appropriately to accommodate this
rotation of the storage vessel from the position of FIG. 1 to that
of FIG. 2.
[0006] FIGS. 3, 4, and 5 illustrate a prior art spread mooring
system where anchor legs 10 at the bow and stem of a storage vessel
extend from the sea floor through an opening in the bottom of the
hull and pass through mooring insert tubes 120, one at the bow and
the other at the stem of the vessel. The anchor legs of FIGS. 3, 4,
and 5 cannot easily be lengthened/shortened to provide a skewed
orientation of a vessel like that of FIGS. 1 and 2.
[0007] Other prior chain supports have included many moving parts
and components which are prone to failure over time such as spring
loaded flappers. Other prior chain support systems are deck mounted
which require hull stiffening to transfer mooring loads. Such prior
configurations require multiple sheaves, portable sheaves or
vertical capstans which require a huge expanse of deck to reach all
anchor legs from a central point.
[0008] 3. Identification of Objects of the Invention
[0009] A primary object of this invention is to provide a spread
mooring arrangement where anchor legs enter the bottom of a vessel
and extend upwardly through mooring insert tubes, one for each
anchor chain, but can easily be lengthened or shortened to provide
skewed headings of the vessel depending on wave, wind and current
conditions.
[0010] Another object of the invention is to provide a trunnion
style chain stopper into a swivel mounted chain support.
[0011] Another object of this invention is to provide a fixed
self-contained modular unit for installation in a vessel for swivel
chain support mounting.
[0012] Another object of this invention is to provide a
self-contained modular unit which is arranged and designed for
installation within the hull of a vessel, below decks, so as to
avoid interference with deck houses, hose hauling and/or process
equipment.
[0013] Another object of this invention is to provide a unit having
a single installation winch at the stern, another at the bow, which
can be moved among a plurality of anchor leg stations respectively
at the stem and bow, to serve all anchor legs.
[0014] Another object of this invention is to provide a swivel
mounted chain support where an anchor chain is pulled in and slides
against a single trunnion guide face.
[0015] Another object of this invention is to provide a swivel
mounted chain support with a single trunnion guide face where
mooring loads between anchor chains and the vessel are transferred
at the head of the trunnion support.
[0016] Another object of this invention is to provide a chain
stopper in a single trunnion guide on a hull mounted chain support,
rather than a deck mounted chain stopper, thereby providing a chain
guidance to assume alignment in the lateral direction with the
flapper of the chain stopper.
SUMMARY OF THE INVENTION
[0017] The objects identified above, along with other features and
advantages result from providing a swivel mounted chain support,
one for each anchor leg, at the bottom end of a mooring insert
tube, so that as the vessel changes its heading, each anchor leg
has its chain support turned to directly face its respective anchor
leg, rather than entering the chain support at an angle. The
mooring insert tube assembly, one for the bow, the other for the
stern, is a fixed self-contained modular unit installed at the bow
or stern of a vessel and includes one or more mooring insert tubes.
A trunnion style chain stopper is mounted in a swiveling base to
allow for rotation about a vertical axis similar to a standard
fairlead sheave. A single winch is installed above the insert tube
assembly with tracks to permit the winch to be moved from alignment
with one mooring insert tube to another.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIGS. 1 and 2 show a prior art spread mooring system where
the vessel may be skewed with respect to a nominal heading by
shortening and lengthening anchor legs at the bow and stem of the
vessel;
[0019] FIGS. 3, 4 and 5 show a permanently moored prior art spread
mooring system with anchor leg insert tubes at the bow and stem of
the vessel;
[0020] FIG. 6 is a partial side cross-section view of the vessel
illustrating stern and bow insert tubes and showing swivel mounted
chain supports according to the invention;
[0021] FIG. 7 is a partial top view of the vessel of FIG. 6 showing
the stem and bow anchor leg orientations;
[0022] FIGS. 8A, 8B, 8C present a more detailed illustration, (with
side, front and top views) of the mounting of the trunnion chain
stopper in a swiveling base for partial rotation about a vertical
axis and partial rotation about a horizontal axis;
[0023] FIG. 9 illustrates an alternative trunnion chain stopper to
that shown in FIGS. 8A, 8B, 8C, for partial rotation about a first
horizontal axis and partial rotation about a second horizontal
axis.
DESCRIPTION OF PREFERRED EMBODIMENT OF THE INVENTION
[0024] The mooring arrangement of FIGS. 6 and 7 is a variant of the
prior art double point mooring arrangement of FIGS. 3, 4, and 5 but
with the improvement of swiveling chain supports 56 which allow
partial rotation or "skewing" of the vessel as in the prior art
arrangement of FIGS. 1 and 2. Unlike the arrangement of prior art
FIGS. 1 and 2, the improved arrangement of FIGS. 6 and 7 are not
routed over and down the sides of the vessel, but are centrally
located in a moonpool area 53 in which the insert tubes are
defined.
[0025] As illustrated in FIGS. 6 and 7, a stern insert tube
assembly 50 or 51 is arranged and designed to be manufactured as a
unit and installed in a moonpool 53 at the stem of a FPSO or other
offshore vessel. The assembly 50 includes a frame 58 and a
plurality of insert tubes 52 mounted on frame 58, for example four
such tubes are evident in the plan view of the stem as shown in
FIG. 7. Such tubes are placed in an arc about the outer periphery
of frame 58 so as to provide a spread array of anchor chains at the
stem of the vessel. Each tube 52 has upper and lower supports 54
from frame 58 to provide vertical passage of an anchor chain from a
swivel mounted chain support 56 mounted at the bottom of the frame
51. A single powered winch 79 is mounted on a deck 99 of the
vessel. The deck 99 is positioned above the assembly 50. The winch
79 is movable on a track 60 such that a pull-in line of the winch
79 can be placed in alignment with any one of the tubes 52 of the
stern insert assembly 50. During mooring operations, the
installation winch 79 is moved from one insert tube 52 to another
along track 60 so that its pull-in cable is aligned with the chain
leg in any one of the insert tubes 52 without additional sheaves,
etc. The swivel mounted chain support 56 swivels to directly face
an anchor chain as it extends into the sea toward its end anchored
in the seabed below.
[0026] Also illustrated in FIGS. 6 and 7 is a bow insert tube
assembly 51 which, like the stem insert assembly 50, is an assembly
which can be prefabricated and mounted within a moonpool 53 in the
bow of the vessel. A plurality of bow insert tubes 57 are mounted
on a frame 55 of the assembly 51. Each bow insert tube is supported
by upper and lower supports 61. Aligned with each bow tube 57 is a
dedicated swivel mounted chain support 56, one for each tube 57. A
single installation winch 81 is mounted on a deck 100 of said
vessel, where the deck 100 is positioned above the top of the
assembly 51. The winch 81 can move on a track 82 so that its
pull-in line is in alignment with the top ends of insert tubes
57.
[0027] The swiveling chain supports 56 can be located both above
and below the keel level. Above keel level placement allows the
entire steel insert tube assembly 50 and 51 support structures to
be installed from above into the moon pool 53 with minimum drydock
requirements. Below keel level installation allows reduction of the
diameter, or size, of the moonpool 53, but requires more drydock
time. Depending on the vessel configuration and overall scheduling,
the combination of a swivel mounted chain support 56 with plural
mooring insert tubes 52, 57 is flexible enough to adapt to the most
desirable solution. The amount of deck machinery, both in number
and cost, for installation of the anchor legs is significantly
reduced due to a centralized location of a winch 79 or 81 on decks
99 or 100 above the assemblies 50 or 51. A single winch 79 or 81
one for the bow, the other for the stern, is all that is needed in
lieu of multiple winches or a single winch with multiple
overboarding fairleads, and several auxiliary sheaves required for
the prior art arrangement of FIGS. 1 and 2.
[0028] FIGS. 8A, 8B and 8C illustrate in side, front and top views
the swiveling chain supports 56 of FIG. 6. A trunnion support 40 is
mounted by means of upper and lower swivel bearings 44, 42 so that
the trunnion support 40 can rotate about a vertical axis 46 of the
support frames 50 or 51. As a result, the trunnion support 40 can
rotate from side to side about axis 46 to directly face an anchor
chain which passes through it. The support 40 includes a hollow
upper shaft 47 through which an anchor chain can pass so as to be
in alignment with a mooring insert tubes 52 or 57 as shown in FIG.
6.
[0029] Bearing blocks 37 are provided between trunnions 35 and
trunnion support 40. A trunnion style chain stopper 82 is installed
in the housing 80. A chain tube 84 carried by housing 80 provides
an entry path for a chain through the chain stopper 82 and through
the hollow shaft 47 at the upper end of the trunnion support.
[0030] As illustrated in FIGS. 8A, 8B and 8C, this trunnion style
chain stopper 82 is mounted into a trunnion housing 40 which itself
rotates about an axis 46 perpendicular to that of the trunnion
rotation axis 45. This arrangement, when used in a spread mooring
system, can accommodate large vessel yaw rotations of up to +/-90
degrees, as illustrated in FIG. 2, from its nominal calm water
heading. This arrangement is particularly applicable to a special
type of spread mooring system which can partially weathervane. The
advantage of integrating a trunnion chain stopper 82 into a
swiveling housing 40 is that an anchor chain passing through it
does not develop inter-link wear due to rotation of the individual
links against one another. By locating the chain stopper 82 between
the bearings 42, 44 of swivel housing 40, excessive loading on the
swivel housing 40 due to chain twisting during vessel rotation is
eliminated. The arrangement of FIGS. 8A, 8B, 8C advantageously
eliminates prior combinations of a fairlead sheave with a separate
chain stopper.
[0031] FIG. 9 illustrates a side view (partially in section) of an
alternative embodiment of the chain support of FIGS. 8A, 8B, 8C. A
chain support 56' is rotatably supported on support frames 50 or 51
with a trunnion support body 40' horizontally mounted via bearings
5, 6 such that the body 40' is free to rotate about a first
horizontal axis 3. A trunnion chain stopper housing 80' is
rotatably mounted on body 40' such that it is free for limited
angular rotation about a second horizontal axis 45'. A chain
stopper 82', is installed within chain stopper housing 80'. A chain
tube 84' is coupled to the inlet of the chain stopper 82'. A chain
8 is illustrated as entering the chain tube 84' and exiting the
chain stopper 82'.
* * * * *