Note: Descriptions are shown in the official language in which they were submitted.
CA 02562823 2006-10-06
PIPE COUPLING AND METHOD FOR INSTALLATION
FIELD
The present invention relates generally to the field of composite pipes, and
in particular
to a coupling for use with composite pipe and a method of installing a
coupling onto
composite pipe.
BACKGROUND
Composite pipe, which for example is sometimes also referred to as fiber-
reinforced
plastic pipe or composite tubing, is well known in the art. These types of
pipe are
generally made of an internal layer of a polymeric material, outer layers of
reinforcing
fibers and polymeric coatings. Composite pipe is particularly useful for
conducting
fluids in oil and gas gathering and piping operations, as it can be flexible
and therefore
spoolable, resulting in faster and more cost-effective installation than pipe
strings which
are assembled from sections of metallic pipe threaded together.
In oil and gas gathering and piping operations, the composite pipe may be
exposed to
aggressive chemicals and harsh conditions. With regard to the conditions that
the pipe
may be exposed to, the load on the pipe, resulting from external pressure,
internal
pressure and tension or compression forces can be very high. The composite
pipe must
be able to withstand these conditions.
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Composite pipe is often used in a manner that requires coupling and uncoupling
of the
pipe at selected locations. A coupling for use with composite pipe must ensure
that the
coupled end of the pipe has at least the same structural integrity as the rest
of the pipe.
The installed coupling should equal or exceed the full design ratings of the
pipe and in
particular the maximum load to which the pipe will be exposed under normal
operating
conditions.
SUMMARY
In accordance with a broad aspect of the invention, there is provided a method
for
installing a pipe coupling on a pipe comprising: providing a pipe coupling
including a
mandrel and an outer sleeve; inserting the mandrel into the pipe inner
diameter of an end
of the pipe with an outboard end of the mandrel protruding from the end of the
pipe;
positioning the outer sleeve substantially concentrically outwardly of pipe in
which the
mandrel is inserted to form a length of substantially concentrically arranged,
overlapping
portions of the mandrel, the pipe and the sleeve; crimping over at least a
portion of the
length to engage the pipe between the sleeve and the mandrel; and, either
before or after
crimping, connecting the sleeve to the outboard end of the mandrel.
In accordance with another broad aspect of the invention, there is provided a
pipe
coupling comprising: a mandrel including an axial passage and an outer
surface, a sleeve
including an inner bore with first and second open ends, the sleeve formed to
be
connectable adjacent the first open end substantially concentrically about the
mandrel
with an outboard end of the mandrel extending beyond the first open end of the
sleeve
and an annular space formed between the sleeve and the mandrel; and an opening
adjacent the second open end positioned to be in communication with the
annular space
when the sleeve is connected concentrically about the mandrel.
It is to be understood that other aspects of the present invention will become
readily
apparent to those skilled in the art from the following detailed description,
wherein
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various embodiments of the invention are shown and described by way of
illustration. As
will be realized, the invention is capable for other and different embodiments
and its
several details are capable of modification in various other respects, all
without departing
from the spirit and scope of the present invention. Accordingly the drawings
and detailed
description are to be regarded as illustrative in nature and not as
restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring to the drawings wherein like reference numerals indicate similar
parts
throughout the several views, several aspects of the present invention are
illustrated by
way of example, and not by way of limitation, in detail in the figures,
wherein:
Figure IA is an axial sectional view of one embodiment of a pipe coupling
according to
the present invention installed on a pipe.
Figures 1B, 1C, 1D and 1E show progressive sectional views of a method for
installing
an end coupling to arrive at the end coupling of Figure 1A.
Figure IA is an axial sectional view of another embodiment of a pipe coupling
according
to the present invention installed on a pipe.
Figure 2B is an exploded view of the pipe coupling of Figure 2A
Figure 3 is an enlarged view of a teethed mandrel surface useful in the
present invention.
Figure 4 is an axial sectional view of an end to end pipe coupling installed
between two
pipes.
DESCRIPTION OF VARIOUS EMBODIMENTS
The detailed description set forth below in connection with the appended
drawings is
intended as a description of various embodiments of the present invention and
is not
intended to represent the only embodiments contemplated by the inventor. The
detailed
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description includes specific details for the purpose of providing a
comprehensive
understanding of the present invention. However, it will be apparent to those
skilled in
the art that the present invention may be practiced without these specific
details.
A coupling according to one aspect of the invention is shown in Figure IA
installed on a
pipe 10. The coupling includes a mandrel 11 and a coupling outer sleeve 13. In
a
method for installing the coupling on a pipe, mandrel 11 is inserted into the
inner
diameter ID of an end of pipe 10 with an outboard end 11 a of mandrel
protruding from an
end of the pipe. Then the outer sleeve 13 is positioned over the pipe to form
a length L of
substantially concentrically arranged, overlapping parts of mandrel 11, pipe
10 and sleeve
13. Then sleeve 13 is crimped over at least a portion of length L that engages
the pipe
between the sleeve and the mandrel. Either before or after sleeve 13 is
crimped over the
pipe, the sleeve is connected to outboard end 11 a of mandrel 11.
An embodiment of a method for installing an end coupling on a pipe is shown in
Figures
113 to 1E to arrive at a connection, for example, such as is shown in Figure
IA.
According to one embodiment of a method, coupling outer sleeve 13 may be
connected
to mandrel 11 so that the sleeve is not able to move axially over the mandrel.
The
connection 14 so formed may also serve to limit the rotational movement of the
sleeve
relative to the mandrel, although this may not always be necessary. Through
the
connection, sleeve 13 is positioned substantially concentrically about mandrel
11 creating
an annular space 16 therebetween. As shown in Figure 1D, an end of pipe 10 can
be
inserted into annular space 16 between the sleeve and the mandrel, which
includes
forcing the pipe over the mandrel. Once the pipe is in position over the
mandrel, sleeve
13 may be crimped over the pipe to engage the pipe between the sleeve and the
mandrel.
It is noted that although the illustrated method secures the sleeve to the
mandrel prior to
inserting the mandrel into the pipe ID, it is to be understood that these
steps may be
reversed if desired. Of course, if sleeve 13 is not connected to the mandrel
before the
pipe is forced over the mandrel and the mandrel includes an outboard
enlargement, such
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as flange 17, that is larger than the inner bore of the sleeve, then the
sleeve must be
inserted over the end of the pipe prior to the mandrel being inserted into the
pipe.
It is further noted that the actual method of securing the coupling outer
sleeve over the
mandrel is not of great importance. However, one way to rigidly attach the
sleeve to the
mandrel against axial movement thereover is to crimp/form the sleeve onto the
mandrel,
as shown in Figures 1. In order to facilitate a crimped connection between the
mandrel
and the sleeve, mandrel 11 may have grooves 18, such as annular indented
grooves, as
shown, grooves formed between ribs, teeth, etc., to engage the crimped
material of sleeve
13. The depth of a groove may be greater than the thickness of the sleeve
material, if
desired. The crimping process may be accomplished in one or more steps, as
desired. In
one embodiment, a first crimping step (Figure 1B) is used to create a crimped
interval 20
of reduced inner diameter IDs on sleeve 13, before the sleeve is positioned
over the
mandrel (Figure IC). Then sleeve 13 is formed along its already crimped
interval 20 to
drive the sleeve 13 into engagement with the mandrel (Figure 1D). Such a two
step
crimping process can allow a selection of crimping die size during the step of
crimping to
the mandrel that is more suitable for the diameter to be crimped. It will be
appreciated,
however, that such a two step process is not the only way to achieve a crimped
connection between sleeve 13 and mandrel 11.
The sleeve may be crimped onto the pipe to form a crimped interval 21
therebetween
through the application of pressure by a circular array of crimping dies 22a -
22g (Figure
1E) as driven by a force generating crimping assembly, which may use for
example
hydraulics. Although seven dies are shown, various numbers of dies may be used
to
crimp the sleeve around its circumference. In the step of crimping the sleeve
over the
pipe, it is desirable to use a crimping process that controls and seeks to
equalize applied
crimping pressure, arrows Pa - Pg, about the crimping circumference, rather
than seeking
equal displacement of crimping dies 22a - 22g. As such, the pressures Pa, Pb,
Pc, Pd, Pe,
Pf and Pg may all be substantially equal. In one embodiment, the pressure
applied at
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each die is generally +/- 2 to 10% of a selected crimp pressure for the
connection. In
such a process for example, the dies may be formed to be substantially of
equal surface
area and the force applied to each die may generated through its own hydraulic
cylinder,
that is monitored and controlled such that the various cylinders apply a force
to their die
which is substantially uniform for the complete array of dies. It is noted
that in such a
process the displacement of the each die in the array may not be substantially
equal to the
displacement of the other dies of the array. Such a process may be useful
achieve a
substantially consistent annular engagement between the sleeve, the pipe and
the mandrel
even if the pipe or the sleeve has a non-uniform wall thickness or a non-
uniform
concentricity. It will be appreciated that the crimp pressure selected for any
connection
depends on the materials of the sleeve and the pipe in that connection.
Crimped interval 21 is positioned along length L of the overlapping sleeve 13,
pipe 10
and mandrel 11.
With reference to Figure 2, it may be desirable to select a total length of an
interval 121
to be crimped with consideration as to the pipe's pitch length Lp. A pitch
length is
defined as a cycle length, indicated as 124, of a spirally wound fiber
reinforcement in a
fiber reinforced pipe 110. In one embodiment of a connection, a length of the
crimped
interval 121 between the sleeve and the pipe, may be selected to be at least
about 80% of
the pitch length Lp or possibly at least about 100% of the pitch length of the
reinforcing
fiber wrap of the pipe.
A single or multiple step crimping process may be used if desired. In one
embodiment
for example, a first crimping step may be performed along a first length L1 of
the sleeve,
but not the full length L. Then a second crimping step may be performed having
a length
L2 that overlaps with the first length L1 crimped in the first step but also
includes a
portion of sleeve 113 not previously crimped. In such a two step crimping
process, it
may be desirable to crimp the first length L1 adjacent a connection 114
between sleeve
113 and mandrel 111 and then select the second crimped length L2 adjacent the
open end
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113a of the sleeve. Such a two step process may allow use of a smaller die set
(i.e. of a
reduced length) and reduce bubbling of residual materials. Of course, spaced
apart
crimps can also be used in a multi-step crimping process, if desired.
In some crimping processes of the present invention, it may be useful to hold
crimping
force for greater than 10 seconds. For example, once a selected maximum
crimping force
is achieved such force may be maintained for >10 seconds and possibly about 15
to 25
seconds. This may be set on the crimping device duration selector. Such a
crimp hold
force may be useful in colder weather operations where the ability of pipe
materials to
elastically deform may be reduced.
If desired, consideration may be given to the construction and materials of
the sleeve and
the mandrel in order to facilitate formation and function of a connection. For
example, as
with pipe 110, the materials of the mandrel and the sleeve may be selected
with
consideration as to the environment in which they are to operate, including
the fluids to
be conveyed through pipe 110 and in which the mandrel inner bore 131 and
possibly the
sleeve may come into contact.
Further, mandrel 111 may be formed to support the force of crimping thereover
without
crushing. Mandrel 111 may also be formed to facilitate and/or control the
positioning of
the other parts, as for example by inclusion of a pipe shoulder 132, which
acts to stop
insertion of pipe 110 and a sleeve positioning shoulder 133, which may be used
to
position and facilitate connection of sleeve 113.
The outer surface of mandrel 113 along length 113 may be formed to be
substantially
cylindrical and may have an outer diameter slightly less than the inner
diameter of the
pipe with which it is to be used, such that the pipe, when forced thereover is
held snugly
thereon and driven into a cylindrical form. In addition or alternately,
inserted end 11 lb
of mandrel 111, which is the end over which pipe 110 is forced, can be formed
such that
when sleeve is connected on the mandrel, inserted end 11 lb extends out beyond
the
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sleeve. In one embodiment, for example, the mandrel and the sleeve are formed
and
configured such that the mandrel extends at least 0.5 and possibly 0.8 mandrel
OD radii
beyond end 113a of the sleeve. The mandrel may be gradually rounded and
tapered at its
inserted end 111b to facilitate installation of pipe 110 thereover. For
example, this
formation of inserted end 111b may cause the pipe to be brought to a circular
condition
before it enters annular space 116, which may permit the inner diameter of
sleeve 113 to
be reduced into close tolerance with the outer diameter of the pipe on the
mandrel.
O-rings 128 or other sealing means may be installed between mandrel 111 and
pipe 110
to seal against fluid flow therepast from the pipe, if desired. In the
illustrated
embodiment, for example, glands 130 may be formed near the end of mandrel to
accept
o-rings 128. If o-rings are used, they are installed before the mandrel is
inserted into the
pipe.
In one embodiment, sleeve 113 may include a hole 134 positioned to allow
permeated
gases trapped in the annulus 116 to vent. Hole 134 may be formed adjacent the
end of
sleeve that will be connected to mandrel and positioned so that therethrough
the
installation of pipe 110 can be observed to be at selected insertion depth.
The inner surface of the sleeve and/or the outer surface along L of the
mandrel may
include teeth 136 thereon to facilitate gripping of the pipe therebetween. The
teeth may
be discreet, continuous circumferentially or spiraling. A non-spiral tooth
form such as a
circumferentially extending tooth may act against interface leakage. The teeth
may be
canted away from the inserted end of the mandrel to act against forces tending
to pull the
pipe out of the coupling. In one embodiment, the teeth may be formed to permit
the
material of the pipe to be forced into the valleys between adjacent teeth
during crimping.
In such an embodiment, with reference to Figure 3, a tooth 234 is shown on a
mandrel
211. Tooth 234 includes a rear tooth face 236 between a tooth crest 234a and
tooth
valley 234b that extends substantially without an overhang of the crest over
the valley.
For example, in the illustrated embodiment the rear tooth face 236 is cut
substantially
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radially at about +1-5 from an orthogonal reference extending radially from
the mandrel
long axis x. Stated another way, the rear tooth face 236, which is the tooth
face directed
toward the mandrel outboard end and away from any forces tending to pull the
pipe out
of the connection, may extend at angle a of 85 -95 from the long axis x of
the mandrel
on which the tooth is formed. The teeth formed on sleeve may also be formed to
facilitate engagement of the material of the pipe.
In the illustrated embodiment, where a V-shaped valley is formed between the
peaks of
an adjacent pair of teeth, the teeth may be formed with 75 to 125 thousands
(of an inch)
spacings S (shown indicating crest to crest spacing) and a height H of 15 to
50 thousands
(valley to crest). In another embodiment shown in phantom at 234c, the valley
between
adjacent teeth is flattened and although the spacing may remain generally
similar to that
previously described; the tooth height may be reduced to 0.010 to 0.050 inch.
In one
embodiment, spacing may be 90 to 110 thousands and tooth height maybe 20 to 40
thousands for discreet valleys or 10 to 20 thousands for a tooth arrangement
with flat
valleys.
A number of different coupling types may be provided according to the present
invention
and three possible types are shown. Figure 1 shows a connection with a flanged
fitting
including a standard ANSI flange connection 17 and sleeve 13 connected to
mandrel 11
through forming operation.
Figure 2 shows outboard end llla formed as a weld-neck fitting. In such a
fitting,
mandrel 111 may be formed of a non-polymeric material, such as metal and such
a
fitting-type may be used to connect a composite pipe 110 to a metallic pipe
(not shown)
by welding between outboard end l 11 a and the metallic pipe. Figure 2 also
shows sleeve
113 attached to mandrel 111 by welds 160, rather than by crimping.
An end to end fitting shown for example in Figure 4, connects two pieces of
pipe 310a,
310b together with or without a flange in between and includes a mandrel 311
with a
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sleeve 313a, 313b connectable on each of its ends. The mandrel of Figure 4 may
include
a groove 162 on which a reusable split-ring tool is attached to facilitate
mandrel handling
for pipe installation and crimping operations.
Some possible benefits of the present connection of mandrel to sleeve may
include: the
press fit of the sleeve onto the mandrel may cause the sleeve to be well-
centered on the
mandrel improving fitting performance and reducing the size of the fitting;
the compact
size allows pre-assembly of standard ANSI flange; the sleeve can be removed
from a
used fitting so that mandrel can be reused; the coupling may provide increased
axial
retention capacity; the coupling arrangement may permit consistent axial
location of
sleeve relative to mandrel; and a low profile fitting adds very little to
diameter of large
diameter pipe. This provides a significant advantage for installation methods
such as
pulling through failed steel pipelines and plowing.
The previous description of the disclosed embodiments is provided to enable
any person
skilled in the art to make or use the present invention. Various modifications
to those
embodiments will be readily apparent to those skilled in the art, and the
generic
principles defined herein may be applied to other embodiments without
departing from
scope of the invention. Thus, the present invention is not intended to be
limited to the
embodiments shown herein, but is to be accorded the full scope consistent with
the
claims, wherein reference to an element in the singular, such as by use of the
article "a"
or "an" is not intended to mean "one and only one" unless specifically so
stated, but
rather "one or more". All structural and functional equivalents to the
elements of the
various embodiments described throughout the disclosure that are known or
later come to
be known to those of ordinary skill in the art are intended to be encompassed
by the
elements of the claims. Moreover, nothing disclosed herein is intended to be
dedicated to
the public regardless of whether such disclosure is explicitly recited in the
claims.
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