Note: Descriptions are shown in the official language in which they were submitted.
CA 02822136 2013-07-24
COUPLING GASKETS AND ASSOCIATED METHODS
This application is a divisional of Canadian Patent Application No. 2,705,351
filed on
October 3, 2008
BACKGROUND OF THE INVENTION
Field of the Invention
Embodiments of the present invention generally relate to coupling devices
used to join sections of pipe and more particularly, to improvements in the
gaskets
used in various pipe coupling devices.
Description of Related Art
A common type of pipe coupling device used to join two pipes employs a
housing with a C-shaped gasket that is designed to straddle the joint between
the
pipes. The portions of the gasket that resiliently contact the outer surface
of each
pipe are often referred to as "sealing lips." The C-shaped gasket design can
provide an effective seal in both vacuum and pressure applications. A cavity
created by the inner surface of the C-shaped gasket functions as a pressure
reservoir. In positive pressure applications, pressure within the piping
system is
applied to the internal surfaces of the gasket via the cavity formed by the
gasket.
This positive pressure increases the force of the sealing lips against the
pipe
surfaces. In a vacuum environment, the sealing lips are drawn tighter against
the
pipe surfaces due to the difference in pressure between the piping system and
atmospheric pressure.
One benefit of these types of coupling devices is that they allow for limited
expansion and contraction of the pipes in the axial direction, while
maintaining
contact between the sealing lips and each pipe's outside surface. Movement of
the
gasket relative to the pipe surfaces can also occur with pressure changes in
the
piping system. Over time, relative movement between the pipes and the gasket
can
wear the gasket sealing lips, which can result in leaks. One known solution to
this
problem is to apply a lubricant, such as grease, to the sealing lips during
the
installation process to reduce wear on the sealing lips. Although this has
improved
the performance of the gaskets, additional improvements are needed because the
grease can be displaced over time thereby allowing the seals to wear. An
additional issue with prior art designs is that gaskets can become damaged
during
installation.
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BRIEF SUMMARY OF THE INVENTION
Various embodiments of the present invention address issues experienced
with known coupling devices, some of which are identified above. In one
embodiment, a coupling for joining two pipes positioned end to end in
substantial
axial alignment is provided. The coupling device includes: a housing having a
plurality of segments configured to straddle the joint, wherein the housing
defines
an annular groove; a plurality of fasteners configured to connect the
plurality of
segments; and an annular gasket with a substantially C-shaped cross-section
that
defines a housing interface portion configured to engage the annular groove
defined by the housing and two sealing portions directed inwardly and
configured
to engage respective outer surfaces of the two pipes, wherein each of the
sealing
portions includes at least one tapered rib having a vertical component and a
horizontal component wherein the vertical component is substantially
perpendicular to the horizontal component.
In another embodiment, an annular gasket is provided. The annular gasket
has a substantially C-shaped cross-section that defines a housing interface
portion
formed on the outer surface of the C-shaped cross-section and two sealing
portions
formed on the outer surface of the C-shaped cross-section proximate the
respective
termination portions of the C-shaped cross section, wherein each of the
sealing
portions includes at least one tapered rib that includes a vertical component
and a
horizontal component and wherein the vertical component is substantially
perpendicular to the horizontal component.
In a further embodiment, an asymmetrical annular gasket is provided. The
asymmetrical gasket includes: a substantially L-shaped housing interface
portion
defining a first leg and a second leg; a pipe sealing portion extending
substantially
perpendicularly from said first leg and including a sealing portion defining
at least
one tapered rib configured to engage an annular surface; and a flange sealing
portion extending substantially perpendicularly from said second leg and
configured to engage a flat surface.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
Having thus described the invention in general terms, reference will now be
made to the accompanying drawings, which are not necessarily drawn to scale,
and
wherein:
Fig. 1 is a pictorial view of a coupling device 20 in accordance with an
embodiment of the present invention;
Fig. 2 is a partial cut-away pictorial view of a coupling device 20 joining
two pipes in accordance with an embodiment of the present invention;
Fig. 3 is a schematic diagram showing a cross-section of a portion of a
coupling device 20 and portions of two pipes;
Fig. 4 is a top view of a gasket 40 in accordance with an embodiment of the
present invention;
Fig. 5 is a cross-section view of the gasket 40 shown in Fig. 4;
Fig. 6 is an enlarged view of the cross-section of the gasket 40 shown in
Figs. 4 and 5;
Fig. 7 is an enlarged view of a cross-section of the pipe interface portion
46A of the gasket 40 shown in Figs. 4-6;
Fig. 8 is a cross-section view of a gasket 70 in accordance with another
embodiment of the present invention;
Fig. 9 is a cross-section view of a pipe interface portion 80A of the gasket
70 shown in Fig. 8;
Fig. 10 is a pictorial view of a flange coupling device;
Fig. 11 is a cross-section view of the gasket 160 shown in Fig. 10;
Fig. 12 is a schematic diagram of a gasket illustrating some options for
movement of mold components used in creating an injection molded gasket;
Figs. 13 A-E are schematic diagrams illustrating cross-sections of different
types of couplings devices that may include a gasket having a tapered rib
design in
accordance with embodiments of the present invention.
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DETAILED DESCRIPTION OF THE INVENTION
The present invention now will be described more fully hereinafter with
reference to the accompanying drawings, in which some, but not all embodiments
of the inventions are shown. Indeed, these inventions may be embodied in many
different forms and should not be construed as limited to the embodiments set
forth
herein; rather, these embodiments are provided so that this disclosure will
satisfy
applicable legal requirements. Like numbers refer to like elements throughout.
Various embodiments of the present invention provide improved coupling
devices for joining pipe ends that have improved sealing performance and/or
manufacturability over known pipe coupling devices. One of the improvements
provided by various embodiments of the present invention is a unique design of
the
gasket. Various embodiments of the gasket include an innovative pipe interface
profile that improves the manufacturability of the gasket itself and its
sealing
performance. Specifically, the pipe interface includes one or more tapered
ribs
with a geometry that allows the use of less complex molds to manufacture the
gasket and also aids in distributing lubricant during the life of the gasket
thereby
providing improved sealing performance. The following paragraphs describe
embodiments of the present invention in relation to a gasket having a C-shaped
cross-section; however, it should be understood that concepts described herein
may
be used in conjunction with other types of gaskets.
Fig. 1 illustrates a coupling device 20 in accordance with an embodiment of
the present invention. The illustrated device 20 includes a housing 25, two
fasteners 30A,B, and a gasket 40. In various embodiments, the housing 25
includes two segments 26A,B, which cooperate to form a cylinder. The housing
segments include flanges 27A-D that are configured to receive fasteners 30A,B
and facilitate connection of the segments. It should be understood that other
embodiments of the present invention may include more than two segments to
create the cylinder. As will be appreciated by those skilled in the art,
couplings for
large pipe diameters often include a greater number of segments to facilitate
installation.
The housing 25 may be constructed of grey iron, ductile iron, steel alloys,
or other suitable material. The housing 25 may be plated with zinc or other
materials such as paint to inhibit corrosion.
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Fig. 2 illustrates how the coupling device 20 connects two pipes 10A,B.
Generally, the two pipes to be joined are positioned end to end and in
substantial
axial alignment. Typically, the pipe ends are spaced apart, but they may be in
contact if desired. The pipes 10A,B include grooves 12A,B formed or cut into
each pipe's outer surface proximate the ends to facilitate attachment of the
coupling device 20 to the pipes 10A,B. Generally, the gasket 40 is positioned
such
that it straddles the joint between the pipes. The housing segments 26A,B are
then
placed over the gasket and secured together using fasteners.
Fig. 3 provides a schematic of a cross-section of a portion of the pipes
10A,B and the coupling device 20. As illustrated, the cross-section of the
housing
25 is substantially U-shaped with one leg 28A of the "U" engaging a groove 12A
in pipe 10A, and the other leg 28B of the "U" engaging a groove 12B formed in
pipe 10B. The inner surface of the U-shaped housing defines a groove that is
sized
and shaped to receive a portion of the gasket 40.
In the illustrated embodiment, the housing 25 is not in rigid contact with
the pipes 10A,B so that the pipes 10A,B are allowed to move or "float" a
limited
amount. For example, the pipes may be allowed to expand axially until the edge
of
the grooves contact an edge of the housing 25. As will be understood by those
skilled in the art, the housing legs 28A,B may be configured to contact the
pipe
grooves to form a rigid connection if desired.
Turning to Figs. 4-7, the gasket 40 is an annular ring having a substantially
C-shaped cross-section. The gasket 40 may be made of an elastomer material
such
as EPDM, nitrile, fluoro-elastomer or silicon. The gasket may be produced
using
an injection, extrusion or compression molding process.
Fig. 6 illustrates the unique cross-section of the gasket 40 in accordance
with an embodiment of the present invention. The gasket 40 has a generally C-
shaped cross-section and is substantially symmetrical about the centerline CL
of
the gasket. The gasket 40 includes a housing interface portion 42 and two pipe
interface portions 46A,B. The housing interface portion 42 generally extends
from
edge 45A to edge 45B along the outer surface of the C-shaped gasket 40. This
portion of the gasket is sized and shaped to engage the inner surface of the
housing
25 as generally shown in Fig. 3.
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The pipe interface portions 46A,B are located proximate the tips 68A,B of
the C-shaped cross-section of the gasket 40 and are configured to resiliently
engage pipe outer surfaces. It should be noted that the pipe interface
portions
46A,B in the illustrated embodiment are substantial mirror images of one
another.
Accordingly, the following discussions regarding concepts embodied in the
interface portion 46A will also apply to 46B. However, it should be understood
that other embodiments of the present invention may include pipe interface
portions that are not mirror images.
Fig. 7 provides an enlarged view of the interface portion 46A. The
interface portion 46A extends generally along the outer surface of the gasket
40
from the leading edge 45A and terminates at tip 68A. For the illustrated
embodiment, the interface portion 46A includes two tapered rib features 50,
60.
Leading into the first rib feature 50 is a horizontal section 47 that is
oriented
substantially perpendicular to and directed towards the centerline CL of the
gasket
40. The first rib feature 50 includes a first vertical component 52 and a
first
horizontal component 54. The first vertical component 52 extends from the
horizontal section 47 in a downward direction and terminates at the edge of
the
first horizontal component 54. The first horizontal component 54 extends
towards
the centerline CL such that the vertical component 52 and horizontal component
54 are substantially perpendicular. In various embodiments, the first vertical
component 52 may also be substantially parallel with the centerline CL of the
gasket 40. As will be understood by those skilled in the art, the tapered rib
feature
is designed such that the vertical component 52 engages the pipe during
installation.
The second rib feature 60 includes a second vertical component 62 and a
second horizontal component 64. The second vertical component 62 extends
substantially perpendicularly from the termination point of the first
horizontal
component 54 in a downward direction and extends to the edge of the second
horizontal component 64. The second horizontal component 64 extends towards
the centerline CL. The second vertical component 62 may be substantially
perpendicular to the second horizontal component 64. A tapered section 66
extends downward in an obtuse angle from the second horizontal section 64 and
terminates at the tip 68A. Although the illustrated embodiment shows two
tapered
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rib features, it should be understood that other embodiments may comprise one
or
more tapered rib features. Furthermore, the figures illustrate the rib
features
themselves as being asymmetrical (e.g., horizontal component longer than
respective vertical component); however, other embodiments may be symmetrical.
As will be understood by those skilled in the art, the tapered rib feature is
designed
such that the vertical component 62 engages the associate pipe during
installation.
Fig. 8 illustrates the cross-section of another embodiment of the gasket 70.
The gasket 70 is an annular ring with a substantially C-shaped cross-section.
The
C-shaped cross-section is substantially symmetrical about the centerline CL.
The
gasket 70 includes a housing interface portion 72, which extends along the
outer
surface of the C-shaped gasket from edge 75A to edge 75B. Also included in the
gasket 70 design are two pipe interface portions 80A,B that extend from the
edge
75A,B to the tips 89A,B, respectively, of the C-shaped gasket. The pipe
interface
portions 80A,B are configured to resiliently engage the pipe surfaces. It
should be
noted that the pipe interface portions 80A,B are substantial mirror images of
one
another. Accordingly, the following discussions regarding the profile of the
interface portion 80A will also apply to interface portion 80B. However, it
should
be understood that other embodiments of the present invention may include pipe
interface portions that are not mirror images.
Fig. 9 provides an enlarged view of the interface portion 80A. As
illustrated, the interface portion 80A includes two rib features 100, 110.
Leading
into the first rib feature 100 is a horizontal section 82, which extends from
edge
75A towards the centerline CL of the gasket. Extending from the horizontal
section 82 is a declined section 84, which extends downwardly at an obtuse
angle
with respect to the horizontal section 82 and generally towards the centerline
CL.
The first rib feature 100 has a first vertical component 102 and a first
horizontal
component 104, where the first vertical component 102 may be substantially
parallel with the centerline CL of the gasket 70. The first vertical component
102
extends from the tapered section 84 in a downward direction and terminates at
the
edge of the first horizontal component 104. The first horizontal component 104
extends towards the centerline CL in an orientation substantially parallel to
the
first horizontal section 82. In the illustrated embodiment, the first vertical
and
horizontal components are substantially perpendicular. Extending from the
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termination of the first horizontal component 104 is a second declined section
86,
which extends at an obtuse angle therefrom. As will be understood by those
skilled in the art, the tapered rib feature is designed such that vertical
component
102 engages the pipe during installation.
The second rib feature 110 includes a second vertical component 112 and a
second horizontal component 114. The second vertical component 112 extends
from the termination point of the second declined section 86 in a downward
direction and extends to the edge of the second horizontal component 114. The
second horizontal component 114 extends towards the centerline CL in an
orientation substantially parallel to the first horizontal section 82 and
terminates at
tip 89A. Although the embodiment illustrated in Figs. 8 and 9 includes two
tapered rib features, it should be understood that other embodiments may
include
one or more tapered rib features.
Fig. 10 illustrates a flange coupling device 150 in accordance with an
embodiment of the present invention. Flange couplings are used to provide a
fluid
tight seal between a pipe end and a mating flange. The illustrated flange
coupling
150 includes two housing segments 152A,B and two fasteners 154A,B for securing
the segments together. The flange coupling device 150 also includes an annular
gasket 160 for providing the fluid tight seal. The gasket 160 is an annular
ring has
an asymmetrical cross-section.
Fig. 11 illustrates the cross-section of the gasket 160, which includes a
housing interface portion 162, a pipe interface portion 170 and a flange
interface
portion 190. The housing interface portion 162 is substantially L-shaped and
extends from edge 166 to edge 167 along the outer surface of the gasket 160.
This
portion of the gasket is sized and shaped to engage the inner surface of the
housing
segments 152A,B. The pipe interface portion 170 extends from edge 167 to tip
185 and is configured to resiliently engage the outer surface of the pipe
being
joined.
In the illustrated embodiment, the pipe interface portion 170 includes a
tapered rib feature 172, which comprises a declined component 176 and a
horizontal component 178. Leading into the tapered rib feature 172 is a first
horizontal section 174 that extends from edge 167 and is oriented
substantially
perpendicular to the adjacent housing interface portion. This horizontal
section
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174 terminates into the first declined section 176 of the tapered rib feature
172.
The declined component 176 is oriented at an obtuse angle with respect to the
horizontal section 174 and terminates in the horizontal component 178 of the
tapered rib feature 172. The horizontal component 178 is substantially
parallel to
the horizontal section 174. The horizontal component 178 terminates in a
radius
180, which itself terminates in a declined section 182. The declined section
182
terminates at the tip 185. Although the illustrated embodiment shows a single
tapered rib feature, it should be understood that other embodiments may
comprise
one or more tapered rib features.
The flange interface portion extends from edge 165 to tip 192 at an obtuse
angle from the adjacent housing interface portion. The flange interface
portion
extends into a radius 194 which extends inwardly.
Methods of Use
As noted, various embodiments of the coupling device 20 may be used to
join two pipes. As a first step in installing the coupling device 20, a
lubricant, such
as grease, is applied to the interface portions 46A,B of the gasket 40. The
gasket
40 is then slid onto the outer surface of pipe 10A such that both interface
portions
46A,B are in contact with the outer surface of pipe 10A. As will be understood
by
those skilled in the art, the vertical components of the tapered ribs on
interface
portion 46A engage the pipe 10A during installation.
Next, a second pipe, 10B, is placed end to end in substantial axial
alignment with pipe 10A such that a gap is present between the ends. The
gasket is
then slid towards pipe 10B until the gasket is substantially centered over the
gap
between the pipe ends such that interface portion 46A is in contact with pipe
10A
and interface portion 46B is in contact with pipe 10B. As will be understood
by
those skilled in the art, the vertical components of the tapered ribs on
interface
portion 46B engage the pipe 10B as the gasket is slid towards pipe 10B.
Once the gasket is positioned, each segment of the housing is positioned
over the gasket and the segments loosely connected using fasteners. After all
of
the housing segments are positioned, the fasteners may be tightened such that
each
segment is rigidly connected to its adjacent segment(s). A cut-away view of a
finished coupling device 20 attached to two pipes is illustrated in Fig. 2.
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As is apparent by the installation procedure described above, the gasket is
repositioned several times during the coupling process. A benefit of the
unique
ribbed profiles described herein is that a portion of the applied grease may
be
retained between the two ribs as well as between the ribs and other features
such as
the leading edge 45 and tip 68A. This creates a small reservoir that can
replenish
grease or other lubricant to the surface of the pipe over time to improve the
durability of the seal.
An additional benefit of the tapered rib geometry is that it adds flexibility
to
the design of molds needed to create the gasket. As one of ordinary skill in
the art
will appreciate, an injection mold may open and close in a direction
substantially
parallel ("B") or perpendicular ("A") to the centerline of the gasket as
generally
shown in Fig. 12 due to the tapered rib geometry profile. If other rib
profiles were
used, the mold would likely have to open and close in direction "C" to reduce
the
chance of deformation of ribs caused by the mold dragging across the rib
profile
when opened to allow the gasket to be removed. It should be noted that molds
used to produce gaskets with the tapered ribbed profiles describe herein may
open
and close in any direction between direction "A" and "B" as desired.
Many modifications and other embodiments of the inventions set forth
herein will come to mind to one skilled in the art to which these inventions
pertain
having the benefit of the teachings presented in the foregoing descriptions
and the
associated drawings. For example, concepts disclosed herein may be used in
conjunction with various pipe couplings marked by Anvil Industries, Inc., such
as
Roughneck , End Guard , Flush Gap , Reducing, and Flange couplings
illustrated in Figs. 13A-E, respectively.
It is to be understood that the inventions are not to be limited to the
specific
embodiments disclosed and that modifications and other embodiments are
intended
to be included within the scope of the appended claims. Although specific
terms
are employed herein, they are used in a generic and descriptive sense only and
not
for purposes of limitation.
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