Note: Descriptions are shown in the official language in which they were submitted.
CA 02796536 2012-11-26
BENDING RESTR1CTOR ASSEMBLY FOR USE WITH A PIPELINE SECTION
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED
RESEARCH OR DEVELOPMENT
Not applicable.
NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT
Not applicable.
INCORPORATION-BY-REFERENCE OF MATERIALS SUBMITTED ON
A COMPACT DISC
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
[0001] The present invention generally relates to apparatus and methods of
controlled bending of
a pipeline beyond elastic limits during the laying of the pipeline in the sea.
In particular, the present
invention relates to apparatus and methods that utilize external forces to
produce controlled bending
of a pipeline beyond elastic limits. The present invention also relates to
bending sleeves that are
used to limiting the amount of bending that can occur in the pipeline during
the laying of the pipeline
or during the maintaining of the pipeline at the sea floor.
2. Description of Related Art Including Information Disclosed Under 37 CFR
1.97 and
37 CFR 1.98.
[0002] Subsea pipelines are typically fabricated one segment at a time aboard
a pipeline-laying
vessel. As each segment is added, the vessel moves forward and the pipeline
follows a descending
path to the sea floor. The suspended pipe span between the vessel stern and
the sea floor is typically
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supported partially by a ramp attached to the vessel stern and axial tension
is applied to the pipe
which maintains the pipeline within elastic boundaries.
100031 The steel pipelines that are laid on the bottom of the sea cannot be
pre-formed or pre-adapted
to the contour of the sea floor. This is because of the above-identified
laying and installation
procedure.
100041 There may be tolerated a certain degree of unevenness over which the
pipeline is capable of
spanning or bending, provided that the specific load does not produce
excessively high stresses in
the pipeline steel or cause vortex-induced vibrations. If stresses exceed
allowable limits, the pipeline
could be deformed permanently, either by buckling or cold bending, or both to
an unacceptable
configuration. Should cold bending occur through yielding of the steel in the
pipeline, it could
propagate uncontrollably. Requirements set by classification societies for
construction and operation
of offshore pipelines permit a certain degree of cold bending beyond elastic
limits provided that it
takes place under controlled conditions. Parameters for such controlled
conditions entail that a
pipeline may be cold bent to a minimum radius less than what is allowed for
uncontrolled bending.
100051 Pipelines that are laid on an uneven sea floor are subjected to free
spanning because of the
rigidity of the pipeline. Specifications used for submarine pipeline
installation permits plastic
deformation as long as positive measures are taken to ensure that excessive
bending is prevented.
By allowing plastic deformation, it is possible to reduce to a considerable
degree the occurrence of
free spanning. Bending beyond elastic limits may be achieved by overloading
the pipeline by
applying external loads.
100061 Submarine pipelines having a diameter of more than twelve inches
usually require a weight
coating to achieve negative buoyancy. This is necessary if the pipeline is to
be submerged and also
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maintain a stable state with respect to the sea current. Plastic deformation
of a pipeline having a
weight coating of concrete will cause the concrete to crack and break loose.
BRIEF SUMMARY OF THE INVENTION
100071 A bending restrictor assembly for use with a pipeline section comprises
first and second
sleeves having an inner diameter greater than the outer diameter of the
pipeline section, an outer
collar slidably positioned relative to and over the first sleeve, and an inner
collar slidably positioned
relative to an interior ofthe outer collar. The inner collar has an inner
diameter greater than the outer
diameter of the pipeline section. The inner collar is positioned spaced
longitudinal relation to an end
of the first sleeve. The inner and outer collars are slidable relative to each
other and relative to a
bending force applied to the pipeline section.
[00081 The outer collar can include a first outer collar that has a portion
overlying a portion of the
first sleeve and another portion overlying a portion of the inner collar, and
a second outer collar has
a portion overlying another portion of the inner collar. The second outer
collar is in longitudinally
spaced relation relative to the first outer collar. The inner collar includes
a first inner collar that is
slidably received within an interior of the portion of the first outer collar
and extends outwardly
therefrom. The first inner collar has an end in spaced relation to an end of
the first sleeve. A second
inner collar is slidably received within an interior of another portion of the
second outer collar.
100091 In the present invention, the first sleeve has at least one hole formed
therein. The outer collar
has at least one keyway overlying the hole of the sleeve. A first pin is
affixed within the hole of the
sleeve and has a portion extending into the keyway of the outer collar.
Additionally, the outer collar
can have a hole formed therethrough in spaced longitudinal relation to the
keyway of the outer collar.
The inner collar has a keyway formed therein. The hole of the outer collar
overlies the keyway of
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the inner collar. A second pin is affixed within the hole of the outer collar
and has a portion
extending into the keyway of the inner collar. The first pin, in the preferred
embodiment of the
present invention, is threadedly received within the hole of the sleeve.
Additionally, in the preferred
embodiment of the present invention, the second pin is threadedly affixed
within the hole of the outer
collar. In a form of the present invention, all of the pins can be affixed
within the outer collars so as
to received by the respective keyways of the inner collars.
100101 Each of the first and second pins has a diameter. Each of the keyways
has a length
dimension. The diameters of the pins and the length dimension of the keyways
correspond to a limit
of a bending radius of the pipeline section. Additionally, a distance between
the end of the first
sleeve and an end of the inner collar corresponds to a limit of the bending
radius of the pipeline.
100111 The outer collar can comprise a plurality of outer collars arranged in
spaced relation to each
other. One of the plurality of outer collars is adjacent the sleeve. Another
of the plurality of outer
collars is away from the first sleeve. The second sleeve is slidably
positioned interior of the another
portion of the collar at the end of the plurality of collars away from the
first sleeve.
100121 The present invention is also a method of the controlled bending of a
pipeline section. This
method includes the steps of: (1) affixing a sleeve around an outer diameter
of the pipeline section;
(2) slidably positioning a portion of an outer collar around an outer diameter
of the sleeve; (3)
slidably positioning a portion of an inner collar within an interior of
another portion of the outer
collar; and (4) securing the portion of the outer collar to the sleeve and
another portion of the outer
collar to the inner collar so as to limit a movement of the outer collar and
inner collar relative to the
controlled bending of the pipeline section so as to limit a radius of bend.
[0013] The steps of securing includes forming a hole into the sleeve, forming
a keyway through a
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wall of the outer collar, and affixing a pin into the hole of the sleeve such
that a portion of the pin
extends into the keyway of the outer collar. The step of securing can also
further include forming a
hole into the outer collar in a position in spaced longitudinal relation to
the keyway of the outer,
collar forming a keyway into a portion of the inner collar, and inserting
another pin through the hole
of the outer collar such that a portion of this another pin resides in the
keyway of the inner collar.
[0014] The method of the present invention can further include laying the
pipeline section, the
sleeve, the outer collar and the inner collar on or adjacent to a sea floor,
and then applying an
external force onto the pipeline section or onto the outer collar so as to
bend the pipeline section
within limits so that the pipeline section has a contour corresponding to a
contour of the sea floor.
The step of applying the external force can include lowering a weighted member
from a sea surface
to the sea floor and then contacting the pipeline section with the weighted
member so as to induce
the bending of the pipeline section. Alternatively, the step of applying the
external force can include
laying the pipeline section from a vessel adjacent an obstacle at the sea
floor, and changing a
direction of the vessel such that the bending of the pipeline section occurs
by contact with the
obstacle.
[0015] This foregoing section is intended to describe the preferred embodiment
of the present
invention. It is understood that variations to the preferred embodiment can be
made within the scope
of the present invention. As such, this section should not be construed as
limiting of the scope of
the present invention. The present invention should only be limited by the
following claims and their
legal equivalents.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0016] FIGURE 1 is a cutaway view of the bending restrictor assembly as
applied to a pipeline
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section in accordance with the teachings of the present invention.
[0017] FIGURE 2 is a plan, partially-transparent view showing the bending
restrictor assembly of
the present invention.
[0018] FIGURE 3 is a partial cross-sectional view showing the bending
restrictor assembly as
applied to a pipeline section in which the bending restrictor assembly is in a
originally assembled
position.
[0019] FIGURE 4 is a partial cross-sectional view of the bending restrictor
assembly as applied to
a pipeline section in which the bending restrictor assembly is shown in
extension.
[0020] FIGURE 5 is a partial cross-sectional view of the bending restrictor
assembly of the present
invention in which bending restrictor assembly is shown in compression.
[0021] FIGURE 5A is a partially cross-sectional view of the present invention
showing an extended
sleeve as epoxy secured to the pipeline section.
[0022] FIGURE 6 is an illustration of an example of how the present invention
serves to reduce free
span.
100231 FIGURE 7 is an illustration showing an early step in the installation
procedure of the pipeline
in accordance with the teachings of the present invention.
[0024] FIGURE 8 is an illustration of a further step in the installation of
pipeline section in
accordance present invention.
[0025] FIGURE 9 is a view showing the operation of the bending restrictor
assembly of the present
invention in association with a mud slide or walking pipeline.
[0026] FIGURE 10 shows the bending restrictor assembly of the present
invention as adapted to
subsurface structures and as adapted to accommodate external loads.
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[0027] FIGURE 11 is an illustration of showing the installation of the
pipeline of the present
invention through the use of horizontal deviations.
[00281 FIGURE 12 shows the use a weight as an external force to induce bending
of the pipeline at
a location where the bending restrictor assembly is attached.
[0029] FIGURE 13A - C show a method of using a weight as an external force to
induce bending
of a pipeline section at a location where a bending sleeve assembly is
attached in different directions.
100301 FIGURE 14 shows the method of FIGURE 13 wherein wires are attached to
winches
mounted on a vessel.
[0031] FIGURE 15 shows the method of the present invention using a winch
mounting on a vessel,
a wire, and a pulley to exert an external force to bend the pipeline attached
to the bending restrictor
assembly.
[00321 FIGURE 16 shows a plan view of the method of the present invention
using a vessel and an
anchor to bend a pipeline section where the bending restrictor assembly is
attached.
4.
100331 FIGURE 17 is a further step in the method shown in FIGURE 16 for the
use of a vessel for
the bending of the pipeline section.
[0034] FIGURE 18 is a plan view of a method using a vessel to install a
pipeline around an immobile
object and showing, in particular, the bending restrictor assembly as attached
to the pipeline.
100351 FIGURE 19 is a plan view showing a further step in the method of FIGURE
18.
DETAILED DESCRIPTION OF THE INVENTION
[0036] Referring to FIGURE 1, there is shown the bending restrictor assembly
10 in accordance with
the teachings of the present invention. As can be seen, the bending restrictor
assembly 10 is applied
to a pipeline section 12. The pipeline section 12 has a length dimension and
an outer diameter. The
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bending restrictor 10 includes a sleeve 14 that is affixed to the outer
diameter of the pipeline section
12. In particular, sleeve 14 is illustrated as affixed to a widened thickness
portion 16 of the pipeline
section adjacent one end of the pipeline section 12. The inclusion of the
length of the pipeline
section12 determined by the installation placement of the sleeve 14 at the
widened thickness portion
16 of the pipeline section 12 assures that bending occurs in the area where
the wall thickness of the
pipeline is minimal, generally in the central area 18.
100371 As can be seen in FIGURE 1, there are plurality of inner collars 24
that are arranged around
the outer diameter of the pipeline section 12 and are positioned in generally
spaced longitudinal
relationship to each other. Each of the collars 24 will extend entirely around
a diameter of the
pipeline section 12. A first outer collar 22 is illustrated as extending over
the outer diameter of the
sleeve 14. A plurality of outer collars 20 are arranged so as to extend
between the respective
plurality of inner collars 24. The plurality of inner collars 24 are arranged
in spaced longitudinal
relationship to each other. Each of the plurality of inner collars 24 will
have an inner diameter
greater than the outer diameter of the pipeline section 12. Each of the inner
collars 24 has an outer
diameter that generally corresponds to the inner diameter of the outer collars
20. As such, the
arrangement of outer collars 20 and inner collars 24 can be slidably linked
together so as to fix the
bending limits of the pipeline section 12.
100381 An outer collar 26 is located at the end of the bending restrictor
assembly 10. Another sleeve
28 is slidably received within the interior of the outer collar 26. The sleeve
28 also extends over a
widened thickness 30 of the pipeline section 12. Sleeves 14 and 20 are
utilized so as to restrict the
bending from affecting the structurally strong connector areas located at the
opposite ends of the
pipeline section 12. As such, the bending restrictor assembly 10 of the
present invention assures the
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integrity of the pipeline section upon which it is placed.
100391 FIGURE 2 shows a circumferential segment of the bending restrictor
assembly 10. As can
be seen, the sleeve 14 is affixed to the pipeline section 12. A pair of slots
32 and 34 are provided
on the sleeve 14 so as to facilitate the ability to weld the sleeve 14 to the
pipeline section 12. The
first outer collar 22 is illustrated as extending over the outer diameter of
the sleeve 14. The outer
collar 22 is illustrated as having a pair of keyways 36 and 38 formed through
the wall thereof. A pin
40 will extend into the keyway 36. Another pin 42 will extend into the keyway
38. The diameter
of the pins 40 and 42, along with the length of the keyways 36 and 38, are
components which
determine the limit of bend of the pipeline section 12. Another sleeve 28 is
formed at the opposite
end of the bending restrictor assembly 10.
100401 The first outer collar 22 also includes a hole 44 formed through the
wall thereof. A pin 46
is threadedly affixed within the hole 44. Another hole 48 is also formed
through the wall of the first
collar 22. A pin 50 is threadedly received by the hole 48. Pins 46 and 48 will
extend radially
inwardly of the outer collar 22 so as to be received by keyways 52 and 54
(illustrated in broken line
fashion) on the inner collar 24.
[004111n FIGURE 2, it can be seen that the inner collar 24 extends through the
space between one
end of the collar 22 and the second collar 56. Second collar 56 has a
configuration similar to that
of the first collar 22. The second outer collar 56 includes suitable keyways
and holes so as to
facilitate the connection with the inner collar 24. It should be noted that,
within the concept of the
present invention, all of the pins could be placed into the outer collar so as
to extend into keyways
in the sleeves and the inner collars. This could facilitate the ability to
assemble the bending restrictor
assembly.
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100421 FIGURE 2 shows a limited arrangement of the outer collars 20 and the
inner collars 24.
Ultimately, the sleeve 28 is illustrated as extending over the pipeline
section 12 at the end of the
arrangement of outer collar 20. The sleeve 28 will include keyway 60 which
serves to receive pins
62 affixed within the holes of the outer collar 56.
100431 FIGURE 3 illustrates the arrangement of the outer collars and inner
collars at the point of
installation upon the pipeline section 12. In FIGURE 3, it can be seen that
the sleeve 14 is welded
to the outer diameter of the pipeline section 12. The sleeve 14 includes a
hole 64 formed at a location
away from the welded connection. The hole 64 is suitably threaded so as to
receive a pin 66 therein.
Pin 66 has a portion extending into the keyway 68 of the outer collar 70.
Because of the use of the
keyway 68, the outer collar 64 will be in slidable relationship with the
sleeve 14. The pin 66 serves
to limit the amount of sliding motion that can occur.
100441 The outer collar 70 has a threaded hole 72 that receives a pin 74
therein. Pin 74 will extend
downwardly so as to be received within a keyway 76 associated with an inner
collar 78. The
arrangement of holes and keyways facilitates the ability to install the
bending restrictor assembly 10
of the present invention. In other words, it is only necessary to align the
respective keyways with
the respective holes. The pins can then be inserted through the keyway so as
to threadedly engage
the hole or threadedly inserted into the threaded hole so as to ultimately
have a portion extending
into the keyway. Other techniques, such as welding or pressing can also be
used so as to cause the
pins to be fixed within their respective holes.
[004511n FIGURE 3, there is a second outer collar 80 also having a keyway 82
and a hole 84 formed
therein. The inner collar 78 includes a hole 86 that serves to receive pin 88
therein. Similarly, a
second inner collar 90 (or sleeve) will have a keyway 92 formed therein. Pin
94 is threadedly affixed
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within hole 84 so as to extend into the keyway 92.
[0046] In FIGURE 3, since each of the respective pins 66, 74, 88 and 94 reside
centrally of the
keyways, the pipeline section 12 is in a straight configuration. The spacing
of the keyways and
holes, along with the spacing of the inner and outer collars, assures that the
bending radius of the
pipeline section 12 is properly controlled.
[0047] FIGURE 4 shows the bending restrictor assembly 10 of the present
invention as used in
extension. In FIGURE 4, the pin 66 has moved so as to abut a side of the
keyway 68. The edge 81
of the sleeve 14 is spaced from the edge 83 of the inner collar 78. Also, the
pin 74 abuts a wall of
the keyway 76. The edge 85 of the outer collar 70 is spaced further from the
edge 87 of the outer
collar 80. Similarly, the pin 88 abuts an end of the keyway 82. Additionally,
and furthermore, the
pin 94 is moved so as to abut an end of the keyway 92 of the inner collar 90.
[0048] FIGURE 5 shows the bending restrictor assembly 10 in compression. In
this arrangement,
the pin 66 abuts another side of the keyway 68. Pin 74 abuts another end of
the keyway 76. Pin 88
abuts another end of the keyway 82. Pin 94 will also abut another end of the
keyway 92. So as to
further restrict bending movement in compression, the end edges 81 and 83 of
the sleeve 14 and the
inner collar 78 abut one another. Similarly, the end edges 85 and 87 of the
outer collars 70 and 80
will abut each other.
[0049] FIGURE 5A shows an alternative embodiment of the present invention in
which an extended
sleeve 14a is affixed with epoxy (or other adhesive) to the outer surface of
pipeline section 12a. The
outer collars 70a and the inner collars 71 have a configuration similar to
that of the previous
embodiment. Another extended sleeve 14c extends from the end of the
arrangements of outer collars
70a and the inner collars 71 opposite to the sleeve 14a. The pipeline section
12a has a generally
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constant wall thickness along its length. The pipeline section I2a lacks the
area of greater wall
thickness of the previous embodiment. The sleeve 14a is not welded to the
outer surface of the
pipeline section 12a.
100501 The sections with increased bending resistance at side of the pipeline
joint are installed to
ensure that the bending takes place at the intended location. The connection
of the pipeline
extensions to the bending restrictor sleeve, after the pipeline splice has
been completed can be by
welding or through the use of a quick connect coupling. The bending resistor
sleeve is connected to
the pipeline with high capacity epoxy. The epoxy connection between the
bending restrictor sleeve
and the pipeline is designed to accommodate the installation tension and the
locating of the bending
sleeve onto the pipeline.
100511 FIGURE 6 shows how the present invention serves as one example of a way
to reduce free
span occurring in the pipeline. In particular, a high spot on the seabed 80 is
creating excess free
spanning of the pipeline. Pipeline 82a has the bending restrictor assembly
affixed thereto. Pipeline
82a is illustrated without the bending restrictor assembly. The section 86a
illustrates the free span
length with the moment relieved through cold bending beyond elastic limits at
80a. Distance 88a
shows the free span without relieving moment. The relieving of moment at the
high spot 80a serves
to reduce the free span length to 86a. As such, it can be seen that the
pipeline 84a with the bending
restrictor assembly of the present invention achieves a more natural angle
with respect extending
from the support 80a to the outer supports 90a and 92a. Additionally, this
arrangement will reduce
the amount of pipeline that is required so as to accommodate the free span.
[00521 FIGURE 7 shows the installation of the pipeline 100 in accordance with
the teachings of the
present invention. Pipeline 100 has bending restrictor assemblies 102 and 104
affixed thereto. The
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pipeline 100 is placed upon the sea floor 106 in a conventional manor. The
pipeline 100 will hang
at a desirable angle from the ramp of a pipe-laying vessel. Another vessel 108
can be utilized so as
to extend a weighted member 110 downwardly from a line 112. This weighted
member 110 can be
placed upon the pipeline 100 in the area of the bending restrictor assemblies
102 and 104. As such,
the pipeline 100 can be bent at a desired angle toward the sea floor 106.
Another weighted member
107 can be used separately from the weighted member 110. This weighted member
107 can also be
lowered from vessel 108. The weighted member acts as a counterweight to
facilitate the bending
of the pipeline at the intended location.
100531 FIGURE 8 shows a further step in the process of the laying of the
pipeline 100 at the sea floor
106. The weighted member 110 has been lowered to its lowermost position at the
end of the line
112. A suitable winch on the vessel 108 it is utilized so as to lower the
weighted member 110. The
bending restrictor assemblies 102 and 104 will allow the pipeline 100 to be
bent at a suitable contour
corresponding to the contour 114 of the sea floor 106. The bending restrictor
assemblies 102 and
104 allow the pipeline 100 to be easily bent without exceeding the plastic
deformation limits of the
pipeline. The weighted members 107 and 110 are properly placed to ensure that
bending takes place
within the central area of the pipeline section. As such, the present
invention facilitates the ability
to conform the pipeline 100 to the contours 114 of the sea floor 106 without
buckling and reduce free
spans. The weighted members 107 and 110 will then stay in place over the
pipeline 100 once the
pipeline is at the sea floor. This serves to limit hysteresis.
[00541 FIGURE 9 shows the utilization of the bending restrictor assemblies of
the present invention
in areas in which a mudslide 120 occurs. As can be seen, the pipeline 122 has
been laid upon the
sea floor 124. The area of the mudslide 120 is defined by sides 126 and 128. A
restraint 130 is
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placed into the sea floor 128. A suitable cable or other line 132 can extend
from the restraint 130
so as to connect with the bending restrictor assembly 134. Another restraint
136 is secured by cable
138 to another bending restrictor assembly 140. Bending restrictor assemblies
134 and 140 are
located along the length of the pipeline 122 to make it bend at the desired
locations.
10055] In FIGURE 9, when a mudslide 120 or walking pipeline should occur, then
the pipeline 122
can bend because of the ability of the bending restrictor assembly 134 and 140
to accommodate such
a bend, The restraints 130 and 136 will limit the amount of travel of the
pipeline 122. When the
ultimate limits of the bending of the pipeline 122 occur, then the bending
restrictor assemblies 134
and 140 will prevent further bending movement of the pipeline 122. As such,
buckling and damage
to the pipeline 122 is effectively prevented and free spans are reduced.
[00561 FIGURE 10 shows the use of external weights 180 that are used to exert
an external force
= onto the bending restrictor assembly (not shown) attached to the pipeline
182. The permanent
weight 180 exerts an external force to the bending restrictor assembly so as
to induce the bending
of the pipeline. The weights 180 are placed on top of and around the pipeline
182 at a section of the
pipeline 182 when the bending restrictor assembly (not shown) is attached. The
bending restrictor
assembly was designed so as to be sufficiently strong to accept permanent
external forces exerted
by the weights 180. The weights 180 can be made of natural material, such as
large rocks, or of
manufactured components (man-made material). The weights 180 are permanently
placed at specific
locations to bend the pipeline 182 to an acceptable bending radius to conform
to the seabed 184.
This approach also provides physical protection for the pipeline 182 from
external forces, such as
ice, wave actions and sea currents. This embodiment, as shown in FIGURE 10, is
particularly useful
at locations where pipelines are laid on the sea floor where rock formations
are present.
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10057] FIGURE 11 shows another technique for bending the pipeline 200 through
the use of
structures located at the sea floor. In particular, obstacles 202 and 204 are
positioned on the sea floor
206. The bending restrictor assembly 208 is located adjacent to the obstacle
202. The bending
restrictor assembly 210 is located adjacent to the obstacle 204. A host or
manifold 210 is connected
to an end of the pipeline 200. The opposite end 212 of the pipeline 200 will
be connected to a
vessel. The vessel can suitably travel so as to deliver the pipeline 200,
along with the bending
restrictor assemblies 208 and 210, in the proximity of the obstacles 202 and
204. As such, the
pipeline 200 can achieve the desired bend by contact with these obstacles 202
and 204. The bending
restrictor assemblies 208 and 210 will assure that the pipeline 200 is not
bent beyond acceptable
plastic deformation limits.
10058] FIGURE 12 shows a method of using a weight 300 as an external force to
induce bending of
a pipeline 305 where a bending sleeve assembly 310 is attached to the pipeline
305 in one
embodiment of the present invention. The pipeline 305 is free spanning over
the sea floor 315. The
weight 300 is placed on top of the bending sleeve assembly 310. The weight 300
is suspended from
one or more elongate flexible members such as a wire 320, where one end of the
elongate flexible
member 320 is attached to the weight 300. Different elongate flexible members,
in addition to wires
can be used to serve the same purpose. For example, a cable, belt, chain,
rope, strap or the like can
be used instead of a wire. The weight 300 is positioned on top of the pipeline
305 where the bending
sleeve assembly 310 is attached. The weight 300 provides an external force on
the bending sleeve
assembly 310 and pipeline 305, permanently bending the pipeline 305 to a
curvature predefined by
the bending sleeve assembly 310. The bending sleeve assembly 310 is designed
to absorb the point
load forces from the weight 300 and restrict the increase in diameter or
flattening as a result of the
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bending of the pipeline 305.
[00591 FIGURES 1 3A-C show a method of using a weight 400 as an external force
to induce
bending of a pipeline 405 where a bending sleeve assembly is attached (not
shown in detail) in
different directions in one embodiment of the present invention. The pipeline
405 is free spanning
over the sea floor 410. The elongated-shaped weight 400 is held by two (or
more) elongate flexible
members such as wires 415 attached to opposite ends of the weight 400.
Different elongate flexible
members, other than wires, can be used to serve the same purpose. For example,
cables, belts, chains,
ropes, straps or the like can be used instead of wires. The angle of the
external force exerted by the
weight 400 can be altered by adjusting the length of the wires 415.
[00601 The weight 400 can exert an external force on the pipeline 405 in
different directions,
depending on the bending requirement. FIGURE 13A shows the weight 400 exerting
an external
force in a vertical direction on the bending sleeve assembly attached to the
pipeline 405. FIGURES.
13B and 13C show one end of the weight 400 resting on the sea floor 410 with
the weight 405
exerting an external force in a diagonal direction on the bending sleeve
assembly attached to the
pipeline 405.
100611 FIGURE 14 shows the method in FIGURE 13A-C where the wires 415 are
attached to
winches 505 mounted on a vessel 500 in one embodiment of the invention. The
winches 505 are
operated to control the angle of the external force exerted by the weight 400
on the bending sleeve
assembly attached to the pipeline 405 by adjusting the lengths of the wires
415. Remotely operated
underwater vehicles (ROVs) with video cameras and other subsea surveying
equipment commonly
known in the industry may be used to guide the position of the weight 400 at
the desired location.
[0062] FIGURE 15 shows a method of using a winch 600 mounted on a vessel 605,
a wire 610, and
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a pulley 615 to exert an external force to bend a pipeline 620 attached to a
bending sleeve assembly
(not shown) in one embodiment of the present invention. One end of the wire
610 is attached to the
winch 600 mounted on the vessel 605 positioned above the bending sleeve
assembly. The wire 610
runs from the winch 600 through the pulley 615 secured to the sea floor 625
below the bending
sleeve assembly. The other end of the wire 610 is attached to the pipeline 620
where the bending
sleeve assembly (not shown) is attached. A different elongate flexible member,
other than a wire,
can be used to serve the same purpose. For example, a cable belt, chain, rope,
strap or the like can
be used instead of a wire. When the winch 600 is activated to pull the wire
610, the pulley 615
directs the wire 610 to exert an external force on the pipeline 620, bending
the pipeline 620 towards
the pulley 615.
100631 FIGURES 16 and 17 show a plan view of a method using a vessel 800 and
an anchor 805 to
bend a pipeline 810 at a section where a bending sleeve assembly 815 is
attached to the pipeline 810
in one embodiment of the present invention. The vessel 800 installs the
pipeline 810 on the sea floor.
The bending sleeve assembly 815 attached to the pipeline 810 is positioned on
the pipeline 810 at
a section where bending is desired. One end of a wire 820 is attached to the
pipeline 810 where the
bending sleeve assembly 815 is attached. The other end of the wire 820 is
attached to an anchor 805
resting on the sea floor. Alternatively, the other end of the wire 820 can be
attached to an immobile
object, a vessel, or the sea floor itself. A different elongate flexible
member, other than a wire, can
be used to serve the same purpose. For example, a cable belt, chain, rope,
strap or the like can be
used instead of a wire. The vessel 800, holding one end of the pipeline 810,
turns in a direction
deviating horizontally away from the anchor 805. As a result, the anchor 805
exerts an external force
on the bending sleeve assembly 815 attached to the pipeline 810, bending the
pipeline 810 in the
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CA 02796536 2012-11-26
direction of the vessel 800. FIGURE 16 shows the pipeline 810 before
controlled bending. FIG. 8B
shows the pipeline 810 after controlled bending.
[00641 FIGURES 18 and 19 show a plan view of a method using a vessel 900 to
install a pipeline
905 around an immobile object 910 where a bending sleeve assembly 915 is
attached to the pipeline
905 in one embodiment of the present invention. The vessel 900 lays down the
pipeline 905 around
the immobile object 910. The bending sleeve assembly 915 attached to the
pipeline 905 is positioned
next to the immobile object 910. The vessel 900, holding one end of the
pipeline 905, turns in a
direction deviating horizontally around the immobile object 910. As a result,
the bending sleeve
asseinbly 915 makes contact with the iminobile object 910 and the reaction
from the immobile object
910 exerts an external force on the bending sleeve assembly 915 attached to
the pipeline 905,
bending the pipeline 905 around the immobile object 910. FIGURE 18 shows the
pipeline 905
before controlled bending. FIGURE 19 shows the pipeline 905 after controlled
bending.
100651 The present invention offers a number of advantages in the laying of
pipeline. The pipeline
length can be reduced by selecting a direct route. This can result in cost
savings. Cold bending is
achieved during pipeline installation operations. This allows the required
additional length of the
pipeline to be created to follow an undulating seabed contour. The bending
restrictor sleeve is
installed on the pipe sections before being added to the pipeline and made
part of the final
installation. The weight coating is not required in those areas where cold
bending takes place. As
such, it will leave an outer diameter similar to the diameter of weight-coated
section. The present
invention further alleviates seabed preparation and post installation
corrections.
100661 The foregoing disclosure and description of the invention is
illustrative and explanatory
thereof. Various changes in the details of the illustrated constructions, or
in the steps of the
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CA 02796536 2012-11-26
described methods, can be made within the scope of the present intention
without departing from the
true spirit of the invention. The present invention should only be limited by
the following claims
and their legal equivalents.
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