U.S. patent application number 11/596437 was filed with the patent office on 2008-03-06 for methods and apparatus for installation of a device about a marine structure.
Invention is credited to Donald Wayne Allen, Stephen Paul Armstrong, Dean Leroy Henning, Li Lee, Kenneth John Loch, Damon Michael McMillan, David Wayne McMillan, Dennis Edward Walker, Christopher Steven West.
Application Number | 20080056828 11/596437 |
Document ID | / |
Family ID | 34965965 |
Filed Date | 2008-03-06 |
United States Patent
Application |
20080056828 |
Kind Code |
A1 |
Allen; Donald Wayne ; et
al. |
March 6, 2008 |
Methods and Apparatus for Installation of a Device about a Marine
Structure
Abstract
Methods and apparatus for the installation of VIV suppression
during the S-Lay installation of a subsea pipeline. A locking
member will be interposed between a pipe and a fairing rotatably
mounted on the pipe, sufficient to bias the fairing against
rotating. Upon marine application, the locking member will degrade,
thereby releasing the fairing.
Inventors: |
Allen; Donald Wayne;
(Richmond, TX) ; Armstrong; Stephen Paul;
(Houston, TX) ; Henning; Dean Leroy; (Needville,
TX) ; Lee; Li; (Houston, TX) ; Loch; Kenneth
John; (Katy, TX) ; McMillan; Damon Michael;
(Humble, TX) ; McMillan; David Wayne; (Deer Park,
TX) ; Walker; Dennis Edward; (Deer Park, TX) ;
West; Christopher Steven; (Pearland, TX) |
Correspondence
Address: |
SHELL OIL COMPANY
P O BOX 2463
HOUSTON
TX
772522463
US
|
Family ID: |
34965965 |
Appl. No.: |
11/596437 |
Filed: |
April 11, 2005 |
PCT Filed: |
April 11, 2005 |
PCT NO: |
PCT/US05/12297 |
371 Date: |
October 4, 2007 |
Current U.S.
Class: |
405/211 |
Current CPC
Class: |
F15D 1/10 20130101; B63B
2021/504 20130101; F16L 1/18 20130101; B63B 39/005 20130101; B63B
21/502 20130101; F16L 1/20 20130101; B63B 2035/442 20130101 |
Class at
Publication: |
405/211 |
International
Class: |
E02D 31/10 20060101
E02D031/10 |
Foreign Application Data
Date |
Code |
Application Number |
May 17, 2004 |
US |
10848547 |
Claims
1. A system for installing vortex induced vibration suppression or
drag reduction devices about a marine structure, comprising: a
mechanism for holding the device relative to the structure in a
preferred orientation while the structure is being installed; and
wherein the mechanism no longer holds the device relative to the
structure in the preferred orientation after the marine structure
has been installed.
2. The system of claim 1, wherein the mechanism comprises material
that will degrade in a marine environment.
3. The system of claim 1, wherein the structure comprises a
tubular, for example a riser.
4. The system of claim 1, wherein the device comprises a
fairing.
5. The system of claim 1, wherein the mechanism comprises at least
one strap that can be broken after the marine structure has been
installed, and/or a pin that can be removed after the marine
structure has been installed.
6. The system of claim 5, further comprising a loop, wherein the at
least one strap is connected to the loop, wherein the loop can be
pulled to break the at least one strap.
7. The system of claim 6, further comprising a plate, wherein the
at least one strap and the loop are connected to the plate.
8. The system of claim 1, further comprising a collar about the
structure, wherein the mechanism connects the device and the
collar, to hold the device relative to the structure in the
preferred orientation.
9. The system of claim 8, wherein the collar has a reduced radius
portion, and an enlarged radius portion, further wherein the
enlarged radius portion extends radially away from the
structure.
10. The system of claim 1, wherein the device comprises a fairing
having a tail, wherein the preferred orientation relative to the
structure during installation comprises turning the tail away from
a stinger during a J-lay installation of the structure.
11. The system of claim 1, wherein the mechanism is adapted to
position a portion of the device radially away from the
structure.
12. A method comprising: (A) positioning and locking the device in
the preferred orientation, such that the device will not be damaged
as it passes over a ramp or roller; and (B) passing the structure
and device over the ramp or roller.
13. The method of claim 12, further comprising after passing the
structure and device over the ramp or roller, disabling the locking
such that the device can move relative to the structure.
14. The method of claim 12, further comprising locking the device
to a collar installed about the structure.
15. The method of claim 12, wherein positioning and locking the
device comprises securing at least one strap to the device and to
the structure or to a second structure connected to the
structure.
16. The method of claim 15, further comprising after passing the
structure and device over the ramp or roller, breaking the at least
one strap to disable the locking such that the device can move
relative to the structure.
17. The method of claim 12, wherein positioning and locking the
device comprises securing at least one pin to the device and to the
structure or to a second structure connected to the structure.
18. The method of claim 16, further comprising after passing the
structure and device over the ramp or roller, removing the at least
one pin to disable the locking such that the device can move
relative to the structure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This Application claims priority to U.S. Non-Provisional
application having Ser. No. 10/848,547, filed on May 17, 2004,
having attorney docket number TH 2463.
FIELD OF THE INVENTION
[0002] In one aspect, the invention relates to apparatus, systems
and methods for reducing vortex-induced-vibrations ("VIV"), current
drag, low frequency drift oscillations due to random waves, and low
frequency wind induced resonant oscillations. In another aspect,
the invention relates to apparatus, systems and methods comprising
enhancement of VIV suppression devices for control of
vortex-induced-vibrations, current drag, low frequency drift
oscillations due to random waves, and low frequency wind induced
resonant oscillations. In another aspect, the invention relates to
apparatus, systems and methods comprising modified and improved
performance fairings for reducing VIV, current drag, low frequency
drift oscillations due to random waves, and low frequency
wind-induced resonant oscillations. In another aspect, the
invention relates to methods and apparatus for "J-Lay" and/or
"S-Lay" installation of pipe. In another aspect, the invention
relates to methods and apparatus installation of VIV suppression
during the "J-Lay" and/or "S-Lay" installation of pipe. In another
aspect, the invention relates to methods and apparatus for
installation of a device about a marine structure.
DESCRIPTION OF THE RELATED ART
[0003] When a bluff body, such as a cylinder, in a fluid
environment is subjected to a current in the fluid, it is possible
for the body to experience vortex-induced vibrations (VIV). These
vibrations are caused by oscillating hydrodynamic forces on the
surface which can cause vibrations of the structure, for example,
if the forcing frequency is at or near a structural natural
frequency. The vibrations may be largest in the direction
transverse to flow, however, in-line vibrations can also cause
stresses which may be larger than those in the transverse
direction.
[0004] Drilling for and/or producing hydrocarbons or the like from
subterranean deposits which exist under a body of water may expose
underwater drilling and production equipment to water currents and
the possibility of VIV. Equipment exposed to VIV includes the
smaller tubes and cables of a riser system, umbilical elements,
mooring lines, anchoring tendons, marine risers, lateral pipelines,
the larger underwater cylinders of the hull of a minispar or spar
floating production system, and any other structure in the body of
water.
[0005] There are generally two kinds of water current induced
stresses to which all the elements of an underwater structure are
exposed. The first kind of stress as mentioned above is caused by
vortex-induced alternating forces that vibrate the underwater
structure in a direction perpendicular to the direction of the
current. These are referred to as vortex-induced vibrations (VIV).
When water flows past the structure, vortices are alternately shed
from each side of the structure. This produces a fluctuating force
on the structure transverse to the current. If the frequency of
this harmonic load is near the resonant frequency of the structure,
large vibrations transverse to the current can occur. These
vibrations can, depending on the stiffness and the strength of the
structure and/or any welds, lead to unacceptably short fatigue
lives. Stresses caused by high current conditions have been known
to cause structures such as risers to break apart and fall to the
ocean floor.
[0006] The second type of stress is caused by drag forces which
push the structure in the direction of the current due to the
structure's resistance to fluid flow. The drag forces may be
amplified by vortex induced vibrations of the structure. For
instance, a riser pipe which is vibrating due to vortex shedding
may disrupt the flow of water around it more so than a stationary
riser. This results in greater energy transfer from the current to
the riser, and hence more drag.
[0007] Many methods have been developed to reduce vibrations of
subsea structures. Some of these methods operate by modifying the
boundary layer of the flow around the structure to prevent the
correlation of vortex shedding along the length of the structure.
Examples of such methods include the use of helical strakes around
a structure, axial rod shrouds, and/or perforated shrouds. Other
methods to reduce vibrations caused by vortex shedding from subsea
structures operate by stabilization of the wake. These methods
include the use of fairings, wake splitters and/or flags.
[0008] VIV may also be a problem for subsea pipelines, especially
the positions of the pipe line that span canyons or trenches on the
ocean floor. These canyons or trenches can act as conduits and
magnify the effects of currents at or near the ocean floor. As with
vertical structures, the solution is to install VIV suppression
such as fairings, wake splitters and flags.
[0009] Installation of VIV suppression after the laying of the
pipeline can be very expensive, laborious, and/or dangerous. It is
generally advantageous that VIV suppression would be installed on
the pipe at the lay vessel as it is being laid.
[0010] There are two main methods of laying pipe, the "J-Lay" and
"S-Lay." With "J-Lay," a vertical lay vessel is utilized, in which
pipe leaves the traveling vessel vertically, with the pipe
essentially forming a "J" as it is being laid on the ocean floor.
With "S-Lay," pipe leaves the lay vessel in an essentially
horizontal position, and rolled off of a radially shaped "stinger"
mounted aft, with the pipe essentially forming an "S" as it is
being laid on the ocean floor. The stinger cross-section is a "V"
shaped trough conveyor comprising a series of rollers across which
the pipe passes. As the stinger is "V" shaped, only a portion of
the pipe engages rollers. The problem with installing VIV during an
S-Lay, is that the stinger may tend to shear off anything that
extends radially from the pipe at those places where it engages the
pipe.
[0011] U.S. Pat. No. 6,695,539 discloses apparatus and methods for
remotely installing vortex-induced vibration (VIV) reduction and
drag reduction devices on elongated structures in flowing fluid
environments. The disclosed apparatus is a tool for transporting
and installing the devices. The devices installed can include
clamshell-shaped strake elements, shrouds, fairings, sleeves and
flotation modules. U.S. Pat. No. 6,695,539 is herein incorporated
by reference in its entirety.
[0012] Thus, there is a need in the art for apparatus, systems and
methods for suppressing VIV and reducing drag of a marine element;
for apparatus, systems and methods for suppressing VIV and reducing
drag of a subsea pipeline, which can be installed during the laying
of the pipeline; and/or for apparatus, systems and methods for
laying a subsea pipeline with devices for suppressing VIV and/or
reducing drag.
[0013] These and other needs of the invention will become apparent
to those of skill in the art upon review of this specification,
including its drawings and claims.
SUMMARY OF THE INVENTION
[0014] In one aspect, the invention provides for apparatus, systems
and methods for suppressing VIV and reducing drag of a marine
element.
[0015] In another aspect, the invention provides for apparatus,
systems and methods for suppressing VIV and reducing drag of a
subsea pipeline, which can be installed during the laying of the
pipeline.
[0016] In another aspect, the invention provides for laying a
subsea pipeline with VIV.
[0017] In another aspect, the invention provides for a fairing for
reducing vortex-induced-vibrations in a cylindrical marine element.
The fairing includes a main body defining a circular passage for
receiving the marine element, and comprising a tail section. A
locking member is supported by the main body, wherein the member is
positionable and lockable in the circular passage against any
marine element in the passage to move the tail section away from
any marine element in the passage, wherein at least a portion of
the locking member may comprise material that will degrade in a
marine environment and upon degradation disengage from the marine
element.
[0018] In another aspect, the invention provides for a modified
pipe, which includes a pipe section, a fairing having a tail
section, and rotatably mounted on the pipe. Also included is a
locking member interposed between the pipe section and the fairing,
biasing the fairing against rotating and/or positioning the tail
section radially away from the pipe section, wherein at least a
portion of the locking member may comprise material that will
degrade in a marine environment and upon degradation will no longer
bias the fairing against rotating, and/or no longer position the
tail section away from the pipe section.
[0019] In another aspect, the invention provides for a method of
modifying a pipe having a fairing rotatably mounted thereon. The
method includes positioning a locking member between the pipe and
the fairing sufficient to bias the fairing against rotating and/or
position a portion of the fairing radially away from the pipe
section, wherein at least a portion of the locking member may
comprise material that will degrade in a marine environment and
upon degradation will no longer bias the fairing against rotating,
and/or no longer position the fairing radially away from the pipe
section. A further aspect may include placing the pipe, fairing and
locking member in a marine environment, and allowing the locking
member to degrade.
[0020] In another aspect, the invention provides for a method of
passing a pipe with a rotatably mounted fairing over a roller,
wherein the fairing comprises a tail section. The method includes
(A) positioning the fairing such that the tail section will not
touch the roller as it passes over the roller. The method also
includes (B) passing the pipe and fairing over the roller. A
further aspect may include, in step (A), further comprising
positioning a temporary locking member sufficient to bias the
fairing against rotating.
[0021] In another aspect, the invention provides for a collar for
securing a fairing rotatably mounted on a pipe. The collar may
include a circular segment of less than 2.pi. radians, and a
circular shaped band positioned around the segment. Other aspects
include modifying a pipe by applying the collar to the pipe,
passing a pipe with the collar over a roller by positioning the
circular segment so that it clears the rollers.
[0022] In another aspect, the invention provides for a system for
installing VIV suppression or drag reduction devices about a marine
structure, comprising a mechanism for holding the device relative
to the structure in a preferred orientation, and wherein the
mechanism no longer holds the device relative to the structure in
the preferred orientation after the marine structure has been
installed.
[0023] In another aspect, the invention provides for a method of
passing a structure with a device having a preferred orientation
relative to the structure over a ramp or roller, the method
comprising positioning and locking the device in the preferred
orientation, such that the device will not be damaged as it passes
over the ramp or roller; and passing the structure and device over
the ramp or roller.
[0024] Even other aspects include modifying a pipe by applying both
the collar and fairing of the invention to the pipe, and passing a
pipe with both the collar and fairing over a roller.
[0025] Still other aspects include S-laying and/or J-laying of pipe
by utilizing the fairing and/or collar.
[0026] These and other aspects of the invention will become
apparent to those of skill in the art upon review of this
specification, including its drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1 is a schematic representation of a "J-Lay"
installation of a subsea pipeline, showing vessel 10 moving in
direction 5 it ocean surface 18, laying pipe 12 onto ocean floor
16.
[0028] FIG. 2 is a schematic representation of an "S-Lay"
installation of a subsea pipeline, showing vessel 20 moving in
direction 5 at ocean surface 18, laying pipe 12 utilizing stinger
22 onto ocean floor 16.
[0029] FIG. 3 is a cross-sectional representation of stinger 22 of
FIG. 2, showing pipe 12 positioned and rolling across rollers
25.
[0030] FIG. 4 is an isometric representation, showing pipe 12,
having VIV fairing 15 and collar 13, positioned and rolling across
stinger 22 in direction 7.
[0031] FIG. 5 is a cross-sectional representation of FIG. 4. taken
at 5-5, showing pipe 12, having VIV fairing 15 and collar 13,
positioned and rolling across stinger 22.
[0032] FIG. 6 is a cross-sectional representation showing fairing
15 mounted on pipe 12, showing gap 3 formed as a result of
gravity.
[0033] FIG. 7 is a cross-sectional representation showing fairing
15 mounted on pipe 12, showing a substantially smaller gap 3 that
can be achieved by lifting fairing 15 in direction 4.
[0034] FIGS. 8 and 9 are a cross-sectional representations showing
failing 15 mounted on pipe 12, showing fairing 15 lifted and held
in place by positioning lock 30.
[0035] FIGS. 10 and 11 are cross-sectional representations of
stinger 22, showing collar 13 mounted on pipe 12.
[0036] FIG. 12 is a cross-sectional representation of stinger 22,
showing fairing 15 mounted on pipe 12.
[0037] FIG. 13 is an isolated representation of collar 13.
[0038] FIG. 14 is a cross-sectional view of pipe 12, failing 15,
and plate 120.
[0039] FIG. 15 is a cross-sectional view of collar 13.
[0040] FIG. 16 is a side view of fairing 15.
[0041] FIG. 17 is a view of a fairing locking system.
[0042] FIG. 18 is a view of a fairing locking system installed
between collar 13 and fairing 15 about pipe 12.
[0043] FIG. 19 is a side view of pipe 12 about which collars 13,
fairings 15, and plates 120 have been installed.
[0044] FIG. 20 is a side view of pipe 12 about which collars 13 and
fairings 15 have been installed.
DETAILED DESCRIPTION OF THE INVENTION
[0045] The invention is best understood by first making reference
to the prior art, and understanding the problem of installing VIV
suppression during an S-Lay installation of pipe.
[0046] Referring to FIG. 1, there is shown a schematic
representation of a prior art "J-Lay" installation of a subsea
pipeline, showing vessel 10 moving in direction 5 at ocean surface
18, laying pipe 12 onto ocean floor 16. The name "J-Lay" comes from
the "J" shape made by pipe 12 during installation. As shown, VIV
suppression is being installed at those locations where pipeline 12
will span channels/trenches 17. Fairings 15 and collars 13 may be
installed.
[0047] Referring now to FIG. 2, there is shown a schematic
representation of a prior art "S-Lay" installation of a subsea
pipeline, showing vessel 20 moving in direction 5 at ocean surface
18, laying pipe 12 utilizing stinger 22 onto ocean floor 16. The
name "S-Lay" comes from the "S" shape made by pipe 12 during
installation.
[0048] Referring additionally to FIG. 3, there is shown a
cross-sectional representation of stinger 22 of FIG. 2, showing
pipe 12 without suppression positioned and rolling across rollers
25.
[0049] Referring additionally to FIGS. 4 and 5, there are shown,
respectively, an isometric representation and a cross-sectional
representation, of pipe 12, having fairing 15 and collar 13, with
pipe 12 positioned and rolling across stinger 22 in direction
7.
[0050] As pipe 12 rolls across stinger 22 in direction 7, any
attached devices, for example collar 13 and fairing 15, may
encounter stinger 22 at point 40, resulting in such collar 13 and
fairing 15 either being broken or sheared off of pipe 12, or held
back at point 40 while pipe 12 passes through such attached
devices, such as the collars and fairings.
[0051] If the tail end of the fairing could be oriented to avoid
stinger 22, then it could pass over stinger 22 intact.
[0052] Gravity may tend to pull the fairing away from the pipe
allowing that portion of the fairing to fall below the pipe and
also engage the stinger. This problem can be seen by reference to
FIG. 6, which is a cross-sectional representation showing fairing
15 mounted on pipe 12, showing gap 3 formed as a result of gravity.
As this fairing 15 approaches the stinger, the portion of the
fairing sagging below the pipe 12 will engage the stinger 22, and
the fairing 15 may either be sheared/knocked off, or held back
while the pipe 12 passes through.
[0053] If the portion of the fairing 15 that sags below the pipe 12
and engages the stinger 22 could be abutted firmly against the pipe
12, that portion of the fairing 15 could pass easily over the
stinger 22.
[0054] In one embodiment, there is disclosed a system for
installing VIV suppression or drag reduction devices about a marine
structure, comprising a mechanism for holding the device relative
to the structure in a preferred orientation, and wherein the
mechanism no longer holds the device relative to the structure in
the preferred orientation after the marine structure has been
installed. In some embodiments, the mechanism comprises material
that will degrade in a marine environment. In some embodiments, the
structure comprises a tubular, for example a riser. In some
embodiments, the device comprises a fairing. In some embodiments,
the mechanism comprises at least one strap that can be broken after
the marine structure has been installed, and/or a pin that can be
removed after the marine structure has been installed. In some
embodiments, the system also includes a loop, wherein the at least
one strap is connected to the loop, wherein the loop can be pulled
to break the at least one strap. In some embodiments, the system
also includes a plate, wherein the at least one strap and the loop
are connected to the plate. In some embodiments, the system also
includes a collar about the structure, wherein the mechanism
connects the device and the collar, to hold the device relative to
the structure in the preferred orientation. In some embodiments,
the collar has a reduced radius portion, and an enlarged radius
portion, further wherein the enlarged radius portion extends
radially away from the structure. In some embodiments, the device
comprises a fairing having a tail, wherein the preferred
orientation relative to the structure during installation comprises
turning the tail away from a stinger during a J-lay installation of
the structure. In some embodiments, the mechanism is adapted to
position a portion of the device radially away from the
structure.
[0055] In one embodiment, there is disclosed a method of passing a
structure with a device having a preferred orientation relative to
the structure over a ramp or roller, the method comprising
positioning and locking the device in the preferred orientation,
such that the device will not be damaged as it passes over the ramp
or roller; and passing the structure and device over the ramp or
roller. In some embodiments, the method also includes after passing
the structure and device over the ramp or roller, disabling the
locking such that the device can move relative to the structure. In
some embodiments, the method also includes locking the device to a
collar installed about the structure. In some embodiments,
positioning and locking the device comprises securing at least one
strap to the device and to the structure or to a second structure
connected to the structure. In some embodiments, the method also
includes after passing the structure and device over the ramp or
roller, breaking the at least one strap to disable the locking such
that the device can move relative to the structure. In some
embodiments, positioning and locking the device comprises securing
at least one pin to the device and to the structure or to a second
structure connected to the structure. In some embodiments, the
method also includes after passing the structure and device over
the ramp or roller, removing the at least one pin to disable the
locking such that the device can move relative to the
structure.
[0056] Referring now to FIG. 7, there is shown a fairing 15 with
its tail oriented to avoid the stinger 22, and that has been
abutted firmly against the pipe 12. FIG. 7 is a cross-sectional
representation showing fairing 15 mounted on pipe 12, showing
fairing tail oriented to avoid stinger 22, and showing that a
substantially smaller gap 3 that can be achieved by lifting fairing
15 in direction 4.
[0057] Once fairing 15 has been lifted in direction 7 is may be
held in place so that it can pass safely over stinger 22. In some
embodiments, there is provided a positioning lock to keep fairing
15 abutted in place while fairing 15 travels over stinger 22. Any
suitable positioning lock 30 may be utilized.
[0058] In some embodiments, positioning lock 30 can be seen by
reference to FIG. 9, in which a wedge 39 has been inserted into the
upper gap between fairing 15 and pipe 12 to minimize gap 3 and abut
fairing 15 against pipe 12. It is envisioned that any suitable
number of wedges may be utilized, and that such wedges may comprise
any suitable shape.
[0059] In some embodiments, positioning lock 30 can be seen by
reference to FIG. 8, which utilizes a set screw/bolt. There is
shown a cross-sectional representation showing fairing 15 mounted
on pipe 12, where fairing 15 is lifted and held in place by
positioning lock 30. Threaded passages 33 may be provided in
fairing 15 for receiving set screws/bolts 35 and 37. In some
embodiments, set screw/bolt 37 may engage pipe 12 directly. In
other embodiments, set screw/bolt 35 engages a pipe contact member
38, which in turn engages pipe 12.
[0060] Once fairing 15 passes over stinger 22, fairing 15 may be
made to freely rotate around pipe 12. While engaged, positioning
lock 30 prevents such free rotation. According to some embodiments
of the invention, position lock 30 may be disengaged after fairing
15 passes over stinger 22. According to some embodiments of the
invention, position lock 30 comprises materials which will degrade
in the aquatic environment and allow free rotation of fairing 15
around pipe 12. The materials may be selected to degrade in the
aquatic environment at a rate slow enough to allow for
installation, but fast enough so that the fairing may properly
operate not too long after installation. The materials may have
physical properties suitable to allow fairing 15 to be locked into
place, and to withstand the rigors in pipe installation, and travel
across the stinger. Not all of positioning lock 30 need be
comprised of degradable materials. As one non-limiting example,
pipe contact member 38 may comprise a degradable material. As
another non-limiting example, set screw/bolt 37 may comprise a
degradable material. As another non-limiting example, even bolt 37
does not have to be made entirely of degradable materials. As
non-limiting examples, only the tip of set screw 37 in contact with
pipe 12 need comprises degradable material, or perhaps the threads
of screw/bolt 37 will degrade. Alternatively, the threads of
threaded passages 33 can be made to degrade, freeing set screw 38.
As even another non-limiting example, a positioning lock 30 with a
degradable locking pin can be easily envisioned.
[0061] Materials that will degrade in marine environments and that
will have adequate physical properties are well known to those of
the materials art. Such materials may be degradable thermoplastics
and/or thermosets and/or metals, for example biodegradable
thermoplastics and/or thermosets.
[0062] In some embodiments, collars 13 are provided to secure
fairings 15 to pipe 12. Specifically, the collars may be designed
to avoid colliding with stinger 22. Referring now to FIGS. 10 and
11, there are shown cross-sectional representations of stinger 22,
showing two embodiments of collar 13 mounted on pipe 12. With
additional reference to FIG. 13, there is an isolated
representation of collar 13. Point 63 is the center of pipe 12
cross-section and of collar 13 cross-section. Assuming a uniform
circular collar 13, the interfering radial portion 65 of collar 13
is that portion which would engage stinger 22, and is that portion
65 of collar 13 between points 61 and 62, defining angle .THETA..
Within this .THETA. radius, collar 13 must be made thin enough to
pass over stinger 22, and in some embodiments is merely a thin band
51. Interfering portion 65 of collar 13 that does not engage
stinger 22 defines an angle (2.pi.-.THETA. radians). Thus for a
stinger having an interference angle with a collar of .theta.
radians, the main body of collar may be less than or equal to
(2.pi.-.THETA. radians), with at least a .THETA. radian portion of
the collar comprising a thin section having a thickness that will
not interfere with passage over the stinger 22. The main body of
collar 13 may extend radially away from pipe 12 a sufficient
distance to secure fairing 15 in place. Collar 13 may be provided
with a band groove 54 for receiving band 51, for example a steel or
inconel band. In some embodiments, a band locking/tightening
mechanism, such as locking bolt/nut 55 may be provided.
[0063] Referring now to FIG. 12, there is shown a cross-sectional
representation of stinger 22, showing fairing 15 mounted on pipe
12. Screw/bolt 35 has been fed through threaded passage 33 to force
pipe contact member 38 into engagement with pipe 12, to hold tail
of fairing 15 away from stinger 22.
[0064] Referring now to FIG. 14, in some embodiments, there is
illustrated pipe 12 about which is installed fairing 15. Fairing 15
includes bolts 106 which hole end plate 108 in place. End plate 108
may be installed at each end of fairing 15 to hold the form of the
fairing. Connector 104 is at tail 105 of fairing 15, which
connector 104 holds tail 105 together. Hole 112 and hole 110 are
provided in fairing 15. Plate 120 is also shown, which includes
hole 122 and hole 124. Straps may be fed through hole 122 and hole
110 to secure tail 105 of fairing 15 in a desired orientation. A
strap may be fed through hole 124 and hole 112 to hold tail 105 of
fairing 15 in a desired orientation.
[0065] Referring now to FIG. 15, in some embodiments, collar 13 is
illustrated. Collar 13 includes flange 140, with hole 142 and hole
144 through flange 140. A straps may be fed through hole 142 of
collar 13 and hole 110 of fairing 15 to keep fairing 15 in a
desired orientation. Also, a strap may be fed through hole 144 of
collar 13 and hole 112 of fairing 15, to hold fairing 15 in a
desired orientation. The straps may also be fed through hole 122 or
hole 124 of plate 120, if desired.
[0066] Referring now to FIG. 16, in some embodiments, a side view
of fairing 15 is illustrated. Fairing 15 includes tail 105, with
connectors 104 holding tail 105 and/or fairing 15 together. Holes
112 are provided at each end of fairing 15, which may be used to
feed a strap through one of more these holes to keep tail 105
oriented in the desired direction.
[0067] Referring now to FIG. 17, in some embodiments, a fairing
orientation system is illustrated. The system includes plate 120.
Loop 150 is connected to plate 120 by connector 152. Strap 130 and
strap 132 are fed around plate 120. Strap 130 is attached to
connector 152 by connection 154. Strap 132 is attached to connector
152 by connection 156.
[0068] In use, plate 120 may be placed between fairing 15 and
collar 13, with strap 130 fed through hole 142 of collar 13 and
hole 110 of fairing 15. Strap 132 may be fed through hole 144 of
collar 13 and hole 112 of fairing 15, where straps 130 and 132 act
to keep tail 105 of fairing 15 in the desired orientation. Any
suitable device may be used to grab loop 150 and pull on loop 150
to break straps 130 and 132 so that fairing 15 is free to
weathervane about pipe 12, for example a cable attached to loop 150
or an ROV arm to grab loop 150.
[0069] Referring now to FIG. 18, in some embodiments, fairing
orientation system is shown attached to pipe 12. Collar 13 is
mounted about pipe 12, and fairing 15 is mounted about pipe 12.
Plate 120 is between collar 13 and fairing 15. Strap 132 is fed
through a hole in fairing 15 and a hole in collar 13 to keep
fairing oriented in the desired direction. Strap 130 is fed through
a hole in collar 13 and a hole in fairing 15 to keep fairing 15
oriented in the desired direction. Connector 152 acts to connect
strap 132 to plate 120 and strap 130 to plate 120, loop 150 to
plate 120. Loop 150 is connected to plate 120, strap 132, and strap
130. When desired, strap breaker 160, for example an ROV, a cable,
or a rope, maybe used to pull loop 150 and break straps 130 and
132, and also remove plate 120, so that fairing 15 is free to
weathervane about pipe 12. In some embodiments, after straps 130
and 132 are broken, broken straps are attached to connector 152,
plate 120, and loop 150, so that the entire fairing orientation
system may be recovered.
[0070] Referring now to FIG. 19, in some embodiments, pipe 12 is
illustrated. Collars 13 are mounted about pipe 12, fairings 15 are
mounted between collars 13 about pipe 12. Each fairing also
includes tail 105 oriented in the desired direction, for example,
in the same direction and/or away from stinger 22. Plates 120 are
provided between fairings 15 and collars 13.
[0071] In some embodiments, in operation, strap 130 may be used to
anchor fairing 15 to collar 13 to keep tail 105 oriented in the
desired direction. Straps may be provided for each of fairings 15,
for example on each side of tails 105.
[0072] In some embodiments, in operation, fairings 15 may be
secured to collars 13 by strap and/or a plate, and then fed off a
ship in a S-lay configuration, over a stinger 22. After pipe 12 has
been fed over stinger 22, straps 130 maybe broken and plates 120
maybe removed so that tails 105 are able to weathervane about pipe
12 between collars 13, having sufficient radial and longitudinal
freedom of motion.
[0073] Referring now to FIG. 20, in some embodiments, pipe 12 is
illustrated. Mounted about pipe 12 are collars 13 and fairings 15.
Each fairing 15 has tail 105 oriented in the desired direction, for
example, in the same direction and/or away from stinger 22. Holding
tails 105 in the desired direction are pin 170, pin 174, pin 178
and pin 182 fed through a hole in collar 13 and into a receiving
hole in fairing 15. Attached to pin 170, pin 174, pin 178 and pin
182 are cable 172, cable 176, cable 180, and cable 184,
respectively. After it is not longer desired that tails 105 be
locked in a certain orientation, pins 170, 174, 178, and 182 may be
removed by pulling on cables 172, 176, 180, and 184. In some
embodiments, the cables may be collected at hub 186 so that hub 186
may be pulled to remove pins 170, 174, 178, and 182.
[0074] In some embodiments, one end of cable 172, cable 176, cable
180, and cable 184 may be retained on the vessel 20, so that after
pipe 12 has been fed over stinger 22 a desired distance, the one
end of the cables may be used to pull out the pins 170, 174, 178,
and 182.
[0075] In some embodiments, hub 186 may be pulled by an ROV or a
cable that has been retained on the vessel 20 after pipe 12 has
been fed over stinger 22.
[0076] While the illustrative embodiments of the invention have
been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the invention. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the invention, including all features which would
be treated as equivalents thereof by those skilled in the art to
which this invention pertains.
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