U.S. patent application number 11/329669 was filed with the patent office on 2006-06-01 for mechanical pipe joint, gasket, and method for restraining pipe spigots in mechanical pipe joint bell sockets.
This patent application is currently assigned to United States Pipe and Foundry Company, LLC. Invention is credited to Daniel A. Copeland, William W. IV Holmes, William H. Owen.
Application Number | 20060113793 11/329669 |
Document ID | / |
Family ID | 34963513 |
Filed Date | 2006-06-01 |
United States Patent
Application |
20060113793 |
Kind Code |
A1 |
Owen; William H. ; et
al. |
June 1, 2006 |
Mechanical pipe joint, gasket, and method for restraining pipe
spigots in mechanical pipe joint bell sockets
Abstract
A mechanical pipe joint, restraining gasket, and method for
restraining pipe spigots within adjacent bell sockets. The
restraining gasket is composed of two axially-separate components:
a sealing portion and a restraining portion made of a plurality of
arcuate locking members. The restraining gasket and a gland
surround an outer surface of the pipe spigot. The mechanical pipe
joint is formed as the pipe spigot is inserted into the bell socket
and the gland is axially attached to the bell socket so that the
restraining gasket is held between: the gland, an inner surface of
the bell socket, and the outer surface of the pipe spigot, so as to
provide a fluid seal in the joint and urge the locking members into
contact with the outer surface of the pipe spigot, axially
restraining the pipe spigot within the bell socket.
Inventors: |
Owen; William H.;
(Fultondale, AL) ; Holmes; William W. IV;
(Birmingham, AL) ; Copeland; Daniel A.; (Bessemer,
AL) |
Correspondence
Address: |
ALSTON & BIRD LLP;BANK OF AMERICA PLAZA
101 SOUTH TRYON STREET, SUITE 4000
CHARLOTTE
NC
28280-4000
US
|
Assignee: |
United States Pipe and Foundry
Company, LLC
|
Family ID: |
34963513 |
Appl. No.: |
11/329669 |
Filed: |
January 11, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10827159 |
Apr 19, 2004 |
|
|
|
11329669 |
Jan 11, 2006 |
|
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|
Current U.S.
Class: |
285/337 |
Current CPC
Class: |
F16L 21/08 20130101;
F16L 47/12 20130101; F16L 21/04 20130101; Y10S 285/91 20130101 |
Class at
Publication: |
285/337 |
International
Class: |
F16L 21/02 20060101
F16L021/02 |
Claims
1. A restraining gasket, for sealing and restraining a male piping
member within an adjoining bell socket along an axis in a
mechanical pipe joint, the restraining gasket being formed at least
in part of an elastomeric material and comprising: a sealing
portion adapted to fit substantially within a sealing cavity
defined between the male piping member and the bell socket; a
restraining portion adapted to surround the male piping member
substantially outside the sealing cavity, the restraining portion
comprising a plurality of circumferentially-spaced arcuate locking
members formed from a rigid material and arranged for restraining
engagement between a bearing surface of a gland and the male piping
member, wherein the locking members are retained relative to each
other by the elastomeric material before attachment of the gland to
the bell socket; and an interface between the sealing portion and
the restraining portion, the interface being adapted to distribute
an axial attachment force exerted by the bearing surface of the
gland on the restraining portion to prevent a premature engagement
of an outer surface of the male piping member by the plurality of
circumferentially-spaced arcuate locking members.
2. The restraining gasket according to claim 1, wherein the
elastomeric material comprises the sealing portion and a plurality
of spacers separate from and adhesively attached to the sealing
portion, and wherein the plurality of circumferentially-spaced
arcuate locking members are retained relative to each other by the
plurality of spacers.
3. The restraining gasket according to claim 2, wherein the
plurality of spacers are composed of an elastomeric material having
a different stiffness than the stiffness of the sealing
portion.
4. The restraining gasket according to claim 2, wherein each spacer
is located circumferentially between two of the
circumferentially-spaced arcuate locking members such that the
plurality of circumferentially-spaced arcuate locking members are
initially suspended out of contact with an outer surface of the
male piping member at a distance of about 0.100 inches from the
outer surface of the male piping member.
5. The restraining gasket according to claim 1, wherein the
plurality of circumferentially-spaced arcuate locking members are
configured to restrain the outer surface of the male piping member
with a means for gripping the outer surface of the male piping
member, the gripping means selected from the group consisting of: a
plurality of teeth; an abrasive grit; a hard granular material; or
a plurality of radial ridges.
6. The restraining gasket according to claim 1, wherein the
interface further defines a slope, the slope being configured to
convert the axial attachment force of the gland into a
partially-axial force and a partially-radial force on the
restraining gasket.
7. The restraining gasket according to claim 6, wherein the slope
is directed radially outward towards the bell socket at an angle of
approximately 10 to 20 degrees, with respect to a plane that is
perpendicular to the axis, such that the partially-axial force is
exerted first on the sealing portion, and the partially-radial
force is exerted second on the plurality of
circumferentially-spaced arcuate locking members so that the axial
attachment force of the gland seals the sealing cavity about the
male piping member before urging the plurality of
circumferentially-spaced arcuate locking members into engagement
with the outer surface of the male piping member so as to axially
secure the male piping member within the bell socket.
8. The restraining gasket according to claim 7, wherein the slope
is directed radially outward towards the bell socket at an angle of
approximately 15 degrees, with respect to a plane that is
perpendicular to the axis.
9. The restraining gasket according to claim 1, wherein an arc
length of each of the plurality of circumferentially-spaced arcuate
locking members is at least 15 degrees, with respect to the
axis.
10. The restraining gasket according to claim 1, wherein an arc
length of each of the plurality of circumferentially-spaced arcuate
locking members is about 60 degrees, with respect to the axis.
11. The restraining gasket according to claim 1, wherein the rigid
material is selected from the group consisting of: hardened metal;
mild steel; ductile iron; ceramic; or plastic having a hardness
greater than that of PVC.
12. A restraining gasket for sealing and restraining a male piping
member within an adjoining bell socket along an axis in a
mechanical pipe joint, the restraining gasket being formed at least
in part of an elastomeric material and comprising: a sealing
portion adapted to fit substantially within a sealing cavity
defined between the male piping member and the bell socket; a
restraining portion adapted to surround the male piping member, the
restraining portion comprising at least one arcuate locking member
formed from a rigid material arranged for restraining engagement
between a bearing surface of a gland and an outer surface of the
male piping member; and a raised portion disposed circumferentially
on a radially-outward surface of the at least one arcuate locking
member such that the raised portion provides a reduced surface area
for reducing friction between the radially-outward surface of the
at least one arcuate locking member and the bearing surface of the
gland.
13. The restraining gasket according to claim 12 wherein the at
least one arcuate locking member comprises a plurality of
circumferentially-spaced arcuate locking members.
14. The restraining gasket according to claim 13, wherein the
elastomeric material comprises the sealing portion and a plurality
of spacers separate from and adhesively attached to the sealing
portion, and wherein the plurality of circumferentially-spaced
arcuate locking members are retained relative to each other by the
plurality of spacers.
15. The restraining gasket according to claim 14, wherein the
plurality of spacers are composed of an elastomeric material having
a different stiffness than the stiffness of the sealing
portion.
16. The restraining gasket according to claim 14, wherein each
spacer is located circumferentially between two of the
circumferentially-spaced arcuate locking members such that the
plurality of circumferentially-spaced arcuate locking members are
initially suspended out of contact with an outer surface of the
male piping member at a distance of about 0.100 inches from the
outer surface of the male piping member.
17. The restraining gasket according to claim 12, wherein the at
least one arcuate locking member is configured to restrain the
outer surface of the male piping member with a means for gripping
the outer surface of the male piping member, the gripping means
selected from the group consisting of: a plurality of teeth; an
abrasive grit; a hard granular material; or a plurality of radial
ridges.
18. The restraining gasket according to claim 13, wherein an arc
length of each of the plurality of circumferentially-spaced arcuate
locking members is at least 15 degrees, with respect to the
axis.
19. The restraining gasket according to claim 13, wherein an arc
length of each of the plurality of circumferentially-spaced arcuate
locking members is about 60 degrees, with respect to the axis.
20. The restraining gasket according to claim 12, wherein the rigid
material is selected from the group consisting of: hardened metal;
mild steel; ductile iron; ceramic; or plastic having a hardness
greater than that of PVC.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 10/827,159, filed Apr. 19, 2004, which is hereby incorporated
herein in its entirety by reference.
FIELD OF THE INVENTION
[0002] The present invention relates generally to mechanical joint
connections between pipe spigots and bell sockets and, more
particularly, relates to a mechanical pipe joint, gasket and method
for more effectively sealing and restraining pipe spigots in
mechanical joint bell sockets using a gasket with a sealing portion
that is axially separated from a restraining portion, the
restraining portion having a plurality of arcuate locking
members.
BACKGROUND OF THE INVENTION
[0003] The construction of pipelines generally involves the axial
connection of two pieces of pipe to form a single pipeline conduit
for transporting materials from one point to another. Along the
pipeline there may be one or more fittings, which allow the pipe
pieces to be joined to other components in the pipeline. The liquid
or gaseous materials usually conveyed via pipelines require that
the pipeline conduits and joints between axially-joined pieces of
pipe, and between pipes and fittings, be substantially leak-proof.
In addition it is advantageous for the axial joint to have
significant strength so as to axially restrain the adjoining pieces
of pipe as flow in the pipeline creates thrust forces between the
pieces of pipe that tend to counteract the attachment forces
axially securing the pipe joint. Those having skill in the art of
pipeline construction are thus in search of pipeline components and
securing methods for more completely securing pipeline joints to
better meet the needs listed above as well as accomplish other
objectives as listed in this application.
[0004] Existing methods for providing a secure pipeline joint can
be distinguished from one another by the procedures and components
utilized to form the pipeline joint. In addition, existing pipeline
joints vary by the way the pipeline connection components, such as
gaskets, locking rings, and other components, are placed and
secured within the pipeline joint. The design parameters of a
pipeline joint are affected by the methods and components used to
construct a given joint, the types of materials transported by the
pipeline, the environment in which the pipeline is situated, and
other pipeline design factors.
[0005] One common method for connecting pipe together involves the
insertion of an end of a male piping member (spigot) into an
expanded end of a second pipe, the interior profile of which has
been specially fabricated to form a socket ("bell socket"). The
bell socket is sized to accommodate the spigot end of the male
piping member to be received. This connection type is known in the
pipe industry as a "push-on joint."
[0006] In order to seal and secure a push-on joint, several methods
are known in the art. One method involves inserting a fitted gasket
within an annular recess formed within the bell socket. Such a
gasket is often specially designed to both seal the pipe joint and
axially-restrain the pipe spigot within the bell socket by
employing stainless steel locking segments that are embedded
circumferentially into the elastomeric material gasket as shown in
U.S. Pat. Nos. 5,295,697 and 5,464,228 issued to J. Weber and L.
Jones on Mar. 22, 1994 and Nov. 7, 1995 respectively. The locking
segments in these gaskets extend from the interior surface of the
gasket, and away from the interior surface of the bell socket, such
that they grip the outer surface of the spigot when the pipeline
conduit is subjected to internal pressures. These gaskets couple
the axial restraint function with the sealing function in a
single-gasket design.
[0007] Another method of axially joining pieces of pipe to form a
pipeline conduit is referred to as a mechanical joint. In this
method, the bell socket has an arrangement for axial attachment to
a corresponding gland that is configured to slidably fit on the
outer surface of the spigot. In mechanical joints such as those
disclosed in U.S. Pat. No. 5,803,513 to Richardson, issued Sep. 8,
1998, an elastomeric gasket and a separate locking ring are
positioned between the gland and the bell socket, so that as the
gland is attached to the bell socket, the elastomeric gasket is
compressed into a sealing position within the bell socket, and the
locking ring is urged into contact with the outer surface of the
pipe spigot. In the Richardson '513 patent, the locking ring is
prevented from prematurely engaging the spigot by the use of skid
pads, which are added to the inner, toothed surface of the locking
ring. While the skid pads in the Richardson '513 patent prevent
premature engagement of the locking ring with the outer surface of
the spigot, they add cost of materials and labor to the
construction of the underlying gasket.
[0008] Other mechanical joint pipe joints are disclosed in U.S.
Pat. No. 5,398,980 to Hunter et al., U.S. Pat. No. 5,335,946 to
Dent et al., and U.S. Pat. No. 4,878,698 to Gilchrist et al. In
these patents, there are disclosed various mechanical joint methods
utilizing a separate restraining (toothed split ring) and sealing
(elastomeric gasket) element positioned within the bell socket and
held in place by an axially-attached gland to seal and restrain
pipe spigots in mechanical pipe joints. The Hunter '980, Dent '946,
and Gilchrist '698 patents all disclose the placement of the
locking elements within the bell socket. As a result, less space is
available within the bell socket for the elastomeric gasket. In
addition, these methods require the use of two separate components
(the split ring and elastomeric gasket) to restrain and seal the
spigot within the mechanical joint.
[0009] EP 0334380 to Imhof et al. discloses another mechanical pipe
joint where the joint is sealed and locked by the interaction of
several separate layered components including: (1) a clamping ring
composed of a plurality of clamping segments, which are
interconnected in the circumferential direction by a rubber layer,
(2) a joint gasket made of soft elastomeric material, and (3) a
sliding ring interposed between the joint gasket and the clamping
ring. Thus, the Imhof patent requires three separate components to
be assembled within the mechanical joint to produce the desired
sealing and locking functions.
[0010] In some mechanical pipe joints, it is advantageous to secure
pipe spigots made of various materials. For instance, in some
cases, there exists a need to secure plastic pipe spigots (such as
PVC piping) within a bell socket composed of a different material
(such as ductile iron). In this case, however, conventional
hardened steel locking segments having a relatively short length
can expose the PVC pipe spigot to large localized forces that might
damage the PVC material.
[0011] In addition, in mechanical piping joints having ductile iron
bell sockets and glands and PVC or other plastic pipe spigots, it
is advantageous to provide a lighter weight gland so that it is
easier for assembly personnel to handle during pipe joint
construction. In prior mechanical joints, such as those described
in the Hunter '980 patent, the gland includes a "forward end" that
extends axially outward from the gland. The extra material added to
the gland in the "forward end" structure adds weight and
manufacturing complexity to the gland structure. Thus, there exists
a need for a mechanical pipe joint that utilizes a more lightweight
gland that is easier to handle and is less likely to damage PVC or
other plastic pipe spigots during pipe joint construction.
[0012] Thus, there exists a need in pipe industry for a mechanical
pipe joint, gasket, and method for restraining a pipe spigot within
a bell socket utilizing an integrated gasket that improves both:
(1) sealing surface area between the inner surface of a bell socket
and outer surface of a pipe spigot, and (2) restraining surface
area between an inner surface of a restraining portion and an outer
surface of a pipe spigot. In addition, there exists a need for
locking elements that exert a restraining force that is evenly
distributed around the entire circumference of the spigot outer
surface, and that engage the spigot outer surface only after the
sealing portion of the gasket has been compressed within the bell
socket. Also, there exists a need for a mechanical pipe joint
gasket that fills the bell socket with an uninterrupted sealing
portion. Finally, there exists a need in the industry for a gasket
that accomplishes these goals with an easy-to-assemble mechanical
pipe joint, that can be utilized with piping components that are
made of various materials, including PVC pipe spigots.
SUMMARY OF THE INVENTION
[0013] The present invention provides an improved restraining
gasket for use in a mechanical pipe joint that improves sealing and
restraint functions in joints between fluid piping members.
Specifically, the invention provides an improved sealing area
between an inner surface of a bell socket and an outer surface of a
pipe spigot. The gasket of the present invention also provides a
more evenly-distributed radial restraining force on an improved
outer surface area of a pipe spigot. The present invention also
provides for a mechanical pipe joint utilizing the gasket, and a
method for restraining a pipe spigot within a bell socket,
utilizing the gasket.
[0014] The gasket is composed of a sealing portion and a
restraining portion. The sealing portion of the gasket is
preferably composed of an elastomeric material and the attached
restraining portion comprises a plurality of
circumferentially-spaced arcuate locking members composed of a
rigid material, each locking member having an inner surface that is
adapted to grip the outer surface of a pipe spigot. The arcuate
locking members may be circumferentially separated by the
elastomeric material of the sealing portion so that the inner
surfaces of the arcuate locking members are held initially out of
contact with the outer surface of the pipe spigot. Alternatively,
the arcuate locking members may be circumferentially separated by a
plurality of spacers that are attached to, but separate from, the
elastomeric material of the sealing portions. According to one
embodiment, the arcuate locking members may be provided with a
raised portion disposed circumferentially on their radially-outward
surface so as to reduce the contact surface area, and resulting
friction, between the locking members and the bearing surface of a
gland.
[0015] The restraining gasket of the present invention is designed
to axially separate the sealing and locking functions of the gasket
and achieve, for example, the following advantages: (1) an increase
in sealing area within the bell socket, (2) an increase in
restraining area in contact with the pipe spigot, as the arcuate
locking members are formed in long arcuate sections to conform to
the cross-section of the pipe spigot outside the bell socket, and
(3) an improved construction of the restraining gasket, so that no
separate locking and sealing parts are required.
[0016] The restraining gasket of the present invention may be used
in the mechanical pipe joint and method of sealing and axially
securing a male piping member within an adjoining bell socket of
the present invention. The mechanical pipe joint includes a
lighter-weight gland having a recessed bearing surface that
contacts the outer surfaces of the arcuate locking members. Since
the gland has a recessed bearing surface, it contains less material
than a standard mechanical joint gland, making it lighter and more
easily manipulated by the technician assembling the joint. In the
mechanical pipe joint of the present invention, the rigid arcuate
locking members may be located outside of the bell socket so that
the gland bearing surface may transmit the axial attachment force
of the gland bearing surface to the axially-adjacent sealing
portion of the gasket. Furthermore, the gland bearing surface may
transmit a portion of the axial attachment force into the radial
direction so as to urge the locking members into contact with the
outer surface of the pipe spigot as the gland is axially attached
to the bell socket.
[0017] The bell socket of the present invention includes a sealing
cavity, which is filled by the sealing portion of the gasket so
that the sealing portion of the gasket resides completely within
the bell socket, axially separated from the restraining portion of
the gasket. This bell socket and gasket arrangement ensures that
the circumferential sealing contact between the sealing portion,
bell socket, and the pipe spigot, is uninterrupted around the
entire circumference of the pipe joint. This feature improves the
sealing surface area of the gasket.
[0018] The interface between the sealing and restraining portions
of the restraining gasket may include a slope so that an axial
attachment force imparted by the gland bearing surface on the
locking members is first transmitted primarily axially to the
sealing portion. This axial force transmission ensures that the
sealing portion is seated within the sealing cavity of the bell
socket and that a more fluid-tight seal exists between the bell
socket, gasket, and spigot. The interface slope may be configured
such that the axial attachment force is then directed more in the
radial direction so as to urge the arcuate locking members into
contact with the outer surface of the pipe spigot once the sealing
portion is seated in the sealing cavity of the bell socket. The
seated sealing portion also provides a resistive axial force due to
its elastomeric compression.
[0019] The gasket, mechanical pipe joint, and method of the present
invention provide a more complete circumferential seal between the
pipe spigot and the inner surface of the bell socket as well as a
more evenly distributed radial locking force between the inner
surfaces of the arcuate locking members and the outer surface of
the pipe spigot. These advantages are provided in a restraining
gasket that is configured for use with an improved method and
mechanical pipe joint utilizing a lighter weight gland and a bell
socket that provides a sealing cavity designed to receive the
sealing portion of the gasket. Additionally, the present invention
provides a more effective distribution of the axial attachment
force imparted on the arcuate locking members by the bearing
surface of the gland so that the sealing portion of the gasket is
fully compressed and seated within the sealing cavity of the bell
socket before the arcuate locking members are urged into radial
contact with the outer surface of the pipe spigot.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The foregoing and other objects or features and advantages
of the present invention will be made apparent from the detailed
description of the preferred embodiments of the invention and from
the following list of drawings which are for illustration purposes
and are not necessarily to scale:
[0021] FIG. 1 is a cross-sectional view of one embodiment of the
mechanical pipe joint of the present invention.
[0022] FIG. 2 is an enlarged cross-sectional view of one embodiment
of the restraining gasket of the present invention.
[0023] FIG. 3 is an elevational view of one embodiment of the
restraining gasket of the present invention.
[0024] FIG. 4 is a cross-sectional view of an embodiment of the
mechanical pipe joint of the present invention utilizing threaded
connectors to attach the gland to the bell socket.
[0025] FIG. 5 is an exploded perspective view of the components of
the restraining gasket of the present invention.
[0026] FIG. 6 is an elevational view of one embodiment of the
restraining gasket of the present invention showing the arc length
of the plurality of circumferentially-spaced arcuate locking
members making up the restraining portion.
[0027] FIG. 7 is a cross-sectional view of another embodiment of
the restraining gasket of the present invention employing a V-slit
to further compress the sealing portion of the restraining
gasket.
[0028] FIG. 8 is a cross-sectional view of a locking member for use
in another embodiment of the restraining gasket of the present
invention employing a raised portion to reduce surface area and
accompanying frictional interaction between a gland bearing surface
and the locking member.
DETAILED DESCRIPTION OF THE INVENTION
[0029] The present inventions now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the invention 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.
[0030] Referring to FIG. 1, the mechanical pipe joint, restraining
gasket and method embodiments of the present invention will be
primarily described in conjunction with mechanical pipe joints
suitable for round cross-section fluid pipelines. It should be
understood, however, that the mechanical pipe joint, restraining
gasket and method embodiments of the present invention can be
utilized in conjunction with a variety of other applications, both
in fluid pipeline conduits and other types of pipelines. For
example, the mechanical pipe joint, restraining gasket and method
embodiments may be utilized in conjunction with gas pipelines and
other applications requiring secure, fluid-tight connections
between adjacent piping conduits having various cross-sectional
shapes. In addition, embodiments of the present invention will be
primarily described in conjunction with mechanical pipe joints
connecting elongate female pipe sections comprising bell sockets
with male pipe sections, however, it should be understood that
embodiments of the present invention may be used with a variety of
fluid piping members, including adjoining male and female pipe
terminal fittings and other pipe fittings having bell sockets
attached thereto configured to receive a male piping member.
[0031] FIGS. 1 and 2 depict one embodiment of the mechanical pipe
joint and restraining gasket of the present invention which is
configured to axially join a male piping member 100 with a female
piping member 200, the female piping member having a bell socket
210 designed for receiving the male piping member. The invention is
particularly useful for male piping members 100 made from polyvinyl
chloride (PVC), high-density polyethylene (HDPE) and/or any other
suitable polymeric material. However, the invention could also be
used with male piping members 100 made from ductile iron, steel
and/or other metals. The female piping member 200 generally will
have a bell socket 210 made from a metal. The male piping member is
axially-secured by a combination of forces imparted on its outer
surface 110 by a gland 300 slidably encircling the outer surface of
the male piping member. A restraining gasket 400 is positioned
between the gland 300, the bell socket sealing cavity 230, and the
male piping member outer surface 110, the restraining gasket 400
having a sealing portion 420 and a restraining portion 430.
[0032] The sealing portion 420 of the restraining gasket 400 is
preferably composed of an elastomeric material 410 so as to provide
a fluid-tight seal in the circumferential sealing cavity 230
defined between the outer surface 110 of the male piping member 100
and the inner surface 220 of the bell socket 210. The sealing
portion of the restraining gasket is configured to fill the sealing
cavity 230 and part of the restraining portion of the restraining
gasket may extend outside the bell socket. As shown in FIGS. 3 and
5, the restraining portion 430 of the restraining gasket 400 is
composed of a plurality of circumferentially-spaced arcuate locking
members 470 formed out of a rigid material. The locking members 470
can be composed out of unhardened metal, mild steel, ductile iron
or ceramic for male piping members 100 made from a polymer. The
locking members 470 can also be formed from a polymeric material if
the material is harder than the polymer of the male piping member.
For male piping members made of metal, the locking members are
formed from a material that is harder than the metal of the male
piping member, such as hardened steel. The arcuate locking members
470 are retained relative to each other by segments of the
elastomeric material 410 extending axially between adjacent arcuate
locking members 470 as shown in FIG. 3. The arcuate locking members
of the restraining portion also include gripping means 460 for
engaging the outer surface 110 of the male piping member 100.
According to various embodiments of the present invention, the
gripping means of the arcuate locking members may include, a
plurality of teeth defined by the arcuate locking member material,
an abrasive grit or other abrasive material affixed to the arcuate
locking members, a plurality of radial ridges defined by the
arcuate locking member material, or another textured material that
is selected to have a gripping ability with respect to the outer
surface of the male piping member.
[0033] In the mechanical joint of the present invention, the gland
300 is axially attached to the bell socket 210 so that a bearing
surface 310 of the gland imparts a force on the restraining portion
430 of the restraining gasket 400. The restraining portion further
transmits a partially axial force to seat and compress the sealing
portion 420 of the restraining gasket 400 within the sealing cavity
230 defined by an inner surface 220 of the bell socket 210. The
restraining portion also receives a partially radial force from the
axial attachment force of the bearing surface 310 of the gland 300
so that the gripping means 460 of the restraining portion 430 are
urged into contact with the outer surface 110 of the male piping
member 100 so as to axially restrain the male piping member within
the bell socket 210.
[0034] Referring now to FIG. 2, which depicts a cross-sectional
view of the restraining gasket 400, an interface 440 is provided
between the restraining portion 430 and the sealing portion 420 of
the restraining gasket, the interface having a slope relative to
the axis of the pipe. The slope of the interface is configured so
that the axial attachment force imparted on the restraining portion
of the restraining gasket is first transmitted to the sealing
portion of the restraining gasket so that the sealing portion is
compressed into the sealing cavity 230 depicted in FIG. 1. After
the sealing portion 420 is fully compressed and seated within the
sealing cavity 230, the axial attachment force imparted on the
restraining portion 430 is directed in the radial direction by the
axially-resistive force of the compressed sealing portion 420 so
that the gripping means 460 of the restraining portion are urged
into contact with the outer surface 110 of the male piping member
100, thereby restraining the male piping member within the bell
socket 210.
[0035] The slope may be tailored to achieve an improved balance
between axial and radial motion transmitted from the gland bearing
surface to the restraining gasket, and in several embodiments of
the present invention, the slope of the interface, or ramp angle
(with respect to a plane that is normal to the pipe axis) may be
set at 20 degrees, 15 degrees, or 10 degrees, respectively. In
other embodiments this ramp angle may also be set at other angles
that provide an improved distribution of the force imparted by the
gland bearing surface so as to delay the radially-inward,
teeth-engaging motion of the locking members until after the
sealing portion has been adequately compressed to achieve a
satisfactory seal.
[0036] As shown in FIGS. 3 and 5, the restraining portion 430 of
the restraining gasket 400 is composed of a plurality of arcuate
locking members 470. In an advantageous embodiment of the
restraining gasket of the present invention, the plurality of
arcuate locking members 470 may be retained relative to each other
by a separate plurality of spacers 480 that are composed of the
same elastomeric material 410 as the sealing portion of the
restraining gasket. Alternatively, the spacers 480 may be composed
of a resilient second elastomeric material having a stiffness that
exceeds the stiffness of the first elastomeric material 410 of the
sealing portion, such that compression of the first elastomeric
material occurs prior to the compression of the second elastomeric
material so that the sealing portion of the restraining gasket is
fully compressed within the sealing cavity 230 before the gripping
means 460 of the arcuate locking members 470 are urged into contact
with the outer surface of the male piping member.
[0037] Preferably, the spacers 480 relatively retain the arcuate
locking members so that the arcuate locking members are initially
suspended radially outward from the outer surface of the male
piping member at a distance of approximately 0.100 inches. As the
gland is tightened, these spacers become compressed in the
circumferential direction as the locking members are forced closer
together at their ends by the radially-inward motion imparted to
them by the gland. In addition, the portion of the spacer
radially-inward of the teeth and engaged against the male piping
member outer surface becomes radially compressed. These
compressions can be adjusted based on the elastomeric stiffness and
dimensions of the spacers to allow the teeth to engage the outer
surface of the male piping member only after the sealing portion of
the gasket has been sufficiently compressed against the outer
surface of the male piping member.
[0038] Additionally, in embodiments of the present invention using
separate spacers 480, the spacers may also be affixed to the
sealing portion 420 and to adjacent arcuate locking members 470
using a various adhesives or glues which are compatible with the
varying types of spacer materials and arcuate locking member
materials.
[0039] FIG. 4 depicts one advantageous embodiment of the mechanical
pipe joint of the present invention wherein the gland 300 is
axially attached to the bell socket 210 using a plurality of
threaded connectors 600 extending through a first plurality of
apertures 320 defined by the gland and a second plurality of
apertures 240 defined by a flange 500 extending radially from the
bell socket. According to this embodiment, the gland is gradually
urged into contact with the restraining portion 430 of the
restraining gasket 400 as the threaded connectors are tightened to
axially attach the gland to the bell socket. In one embodiment, the
threaded connectors are T-head bolts, as depicted in FIG. 4 which
are secured axially through the corresponding first and second
plurality of apertures 320, 240 by a plurality of threaded nuts
601.
[0040] Referring now to FIG. 6, which shows a front view of the
restraining gasket 400 according to one embodiment of the present
invention, an arc length 490 of the arcuate locking members is
shown. In the depicted embodiment, the arc length is approximately
60 degrees with respect to the pipe conduit axis, such that the
restraining portion of the restraining gasket contains 6 arcuate
locking members. In other embodiments, the arc length may be varied
such that the restraining portion 430 is composed of more or less
individual arcuate locking members 470.
[0041] FIG. 7 shows an alternate embodiment of the restraining
gasket 400 of the present invention wherein the sealing portion 420
includes a V-notch 421 that faces the bell socket 210 such that
when the pipe conduit is pressurized with a flow of fluid, the
V-notch fills with fluid so as to more fully expand the sealing
such that the sealing cavity 230 is more completely filled by the
sealing portion. In addition, the sealing portion of the
restraining gasket may be fitted with a wiper seal so that the
internal pressure generated within the connected piping members
aids in compressing the sealing portion within the sealing cavity
defined in the bell socket.
[0042] FIG. 8 shows an alternate embodiment of the arcuate locking
member 470 of the present invention wherein the radially-outward
surface of the arcuate locking member comprises a raised portion
475 extending circumferentially along the arc length of the arcuate
locking member. The raised portion 475 reduces the frictional
forces produced as the arcuate locking member 470 interacts with
the bearing surface 310 of the gland 300. The raised portion 475
provides a reduced surface area of interaction between a
radially-outward surface of the arcuate locking member 470 and the
bearing surface 310 of the gland 300 such that less axial force is
required during assembly of the mechanical pipe joint of the
present invention. In addition, the raised portion 475 provided in
this embodiment allows the cross-sectional profile of the arcuate
locking segment 470 to be reduced. For example, the raised portion
475 may replace the flat surface of the arcuate locking segment (as
depicted, for example, in FIG. 2) that would otherwise directly
contact the bearing surface 310 of the gland 300.
[0043] Referring again to FIG. 1, a method for axially securing a
male piping member within a bell socket is described. First, the
components of the pipe joint are provided, including, the
restraining gasket 400, the male piping member 100, the bell socket
210, and the gland 300. Next, the gland 300, followed by the
restraining gasket 400, is placed respectively around the outer
surface 110 of the male piping member so as to surround the male
piping member. Then the male piping member, encircled by the
restraining gasket and gland, is inserted into the bell socket so
that the sealing portion of the restraining gasket is positioned
within the sealing cavity 230 defined by the inner surface 220 of
the bell socket. Finally, the gland is moved axially towards the
bell socket so that the gasket is sandwiched axially between the
gland and the bell socket. The gland defines a bearing surface 310
that contacts the restraining portion 430 of the restraining
gasket. The gland is axially-attached to the bell socket so that
the bearing surface of the gland is gradually brought into contact
with the restraining portion of the restraining gasket.
[0044] As the bearing surface of the gland contacts the restraining
portion, an axial force is first directed towards the sealing
portion so that the elastomeric material 410 of the sealing portion
is compressed within the sealing cavity 230 so that a fluid-tight
seal is formed between the outer surface of the male piping member
and the inner surface 220 of the bell socket. As the sealing
portion becomes fully seated in the sealing cavity, the axial force
produced by the bearing surface is then directed more in the radial
direction so that the bearing surface of the gland then urges the
gripping means 460 of the restraining portion of the restraining
gasket into contact with the outer surface of the male piping
member, thus axially-securing the male piping member within the
bell socket with a fluid-tight seal provided by the
fully-compressed and seated sealing portion of the restraining
gasket.
[0045] 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. Therefore, 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.
* * * * *