AU2013204192A1 - Seal and fluid conduit incorporating same - Google Patents

Abstract

There is disclosed an elastomeric seal for sealing between first and second sections of a fluid conduit in which an end of the first section is received in the second section whereby an annular space is defined between said end and said second section, the seal comprising a radially inner sealing portion receivable against an outer face of said end and a radially outer sealing portion receivable against an inner face of the second section, whereby sealing is effected in the annular space, wherein the radially inner sealing portion comprises an annular lip which projects generally axially beyond the radially outer sealing portion. -18 'AA /1920 8 1 17 5 i I1 I

Description

1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 SEAL AND FLUID CONDUIT INCORPORATING SAME The present invention relates to a seal for sealing between first and second sections of a fluid conduit. The invention has particular, though not necessarily exclusive, application 5 to underground water mains piping. End-to-end joining of underground water mains pipes is typically effected by means of a socket, into which the adjacent ends of the pipes are received. Typically, a respective elastomeric sealing ring is fitted between each pipe end and the socket, the ring engaging 10 an outer circumferential face of the end and an inner circumferential face of the socket, thereby effecting sealing between the faces. Satisfactory sealing relies on not only adequate alignment between each pipe and the socket to which it is coupled, but also in the deviation of the exterior configuration of the 15 pipe end from truly cylindrical being within certain limits. Distortion of a given pipe, whereby its external configuration is not truly cylindrical, can be caused by ballooning of the pipe under mains pressure or ovality in the pipe cross-section, the latter being a problem frequently encountered where the pipe is formed from polyvinyl chloride (PVC), particularly PVC-O, which may result in the manner in which the pipe is stored prior to 20 installation. There is a need in the art for a seal which, when installed, effects reliable sealing between the pipe end and socket, particularly where there is distortion or misalignment. 25 According to a first aspect of the present invention, there is provided an elastomeric seal for sealing between first and second sections of a fluid conduit in which an end of the first section is received in the second section whereby an annular space is defined between said end and said second section, the seal comprising a radially inner sealing portion receivable against an outer face of said end and a radially outer sealing portion receivable against an 30 inner face of the second section, whereby sealing is effected in the annular space, wherein the radially inner sealing portion comprises an annular lip which projects generally axially 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -2 beyond the radially outer sealing portion. The lip may be surrounded by pressurised fluid in the annular space and thereby forced against said inner face. 5 In one embodiment of the invention, the seal has an outer diameter of about 13cm to about 16cm, and preferably about 14.5cm, and an inner diameter of about 10cm to about 12cm, and preferably about 11cm. Preferably, in that embodiment, the lip has a thickness of about 0.2cm to about 0.3cm. More preferably, in that embodiment, the lip has a thickness 10 of about 0.25cm. Preferably, in that embodiment, the lip has a length of about 0.4cm to about 0.7cm. More preferably, in that embodiment, the lip has a length of about 0.55cm. Preferably, said annular lip is of substantially uniform thickness along its length. 15 According to a second aspect of the present invention, there is provided a fluid conduit comprising first and second sections, an end of the first section being received in the second section whereby an annular space is defined between said end and said second section, and an elastomeric seal having a radially inner sealing portion received against an outer face of said end and a radially outer sealing portion received against an inner face of 20 the second section, whereby sealing is effected in the annular space, the radially inner sealing portion comprising an annular lip which projects axially beyond the radially outer sealing portion to be surrounded by pressurised fluid in the annular space and thereby forced against said inner face. 25 Preferably, the seal is configured with an annular cavity a radially inner wall of which is defined by a proximal portion of the lip, the cavity being radially inward of the radially outer sealing portion and opening axially so as to be occupied by pressurised fluid in the annular space. Pressurised fluid occupying the annular cavity forces said proximal portion against said radially outer face. Preferably, the annular cavity has a generally axially 30 facing side surface at an end thereof which is opposite to an end thereof at which it opens axially. Preferably, the side surface has a radial length at least twice the thickness of said 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -3 annular lip. Said radial length may be two to four times the thickness of said annular lip. Preferably, said side surface comprises a face which is substantially perpendicular to the central axis of the seal. 5 Preferably, the radially outer sealing portion comprises a circumferential lip which projects to define a radially outer wall of the cavity, whereby to be forced against the inner face of the second section by pressurised fluid occupying the cavity. That lip may have a thickness which is generally similar or equal to the thickness of said annular lip. 10 Preferably, the radially outer sealing portion comprises a sealing face which has a substantially straight axial cross-sectional profile. Preferably, said profile is aligned with a central axis of the seal. Preferably, the radially inner sealing portion comprises a sealing face which has a 15 substantially straight axial cross-sectional profile. Preferably, that profile is angled with respect to the central axis of the seal whereby an opening defined through the seal is tapered to facilitate fitting of the seal to the first section. Preferably, the seal includes a substantially solid annular body region extending from a 20 sealing face of the radially inner sealing portion to a sealing face of the radially outer sealing portion so as to be compressed when said sealing is effected whereby to urge the radially inner sealing portion and radially outer sealing portion against said outer face and said inner face respectively. In a preferred embodiment of the invention, the body region defines a proximal section of the radially inner sealing portion. In a preferred embodiment 25 of the invention, said radially outer sealing portion comprises said circumferential lip and said body region defines a proximal section of the radially outer sealing portion. Preferably, a radial length of the body region is at least twice an axial length of the body region. Preferably, said radial length is two to three times the axial length. 30 In a preferred embodiment of the invention, an axial end section of the seal which comprises the sealing portions includes said body region.

1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -4 Preferably, the seal is configured with a retaining formation engageable with a complementary retaining formation with which the second conduit section is configured so as to be located within the second section and restrained from axial displacement relative 5 thereto during insertion of said end into the second conduit section. Preferably, the retaining formation of the seal comprises a circumferential shoulder receivable against a radially inwardly projecting circumferential bead defining the retaining formation of the second conduit section. Preferably, the seal is configured with a radially outwardly opening circumferential groove which defines the shoulder and is arranged to receive the 10 bead. Preferably, an axial end section of the seal which comprises said shoulder has a hardness which is greater than a hardness of an axial end section of the seal which comprises the sealing portions. The section comprising the shoulder preferably has a hardness of about 70 Shore A to about 100 Shore A, and more preferably a hardness of about 80 Shore A to about 90 Shore A, and the section comprising the sealing portions has 15 a hardness 45 Shore A to about 60 Shore A, and more preferably a hardness of about 50 Shore A to about 55 Shore A. In a preferred embodiment of the invention, the first conduit section comprises plastic pipe. Preferably, the plastic is polyvinylchloride (PVC). Preferably, the plastic is PVC-0. 20 Alternatively, the plastic may, for example, be PVC-U or PVC-M. In an alternative embodiment of the invention, the first conduit section comprises metal pipe. The metal may comprise, for example, ductile iron. In a preferred embodiment of the invention, the second conduit section is defined by a 25 fitting. The fitting may interconnect the first section and at least one further conduit section. The fitting may comprise a socket. Preferably, the second conduit section is metal. 30 According to a third aspect of the present invention, there is provided a method of assembling a fluid conduit, comprising effecting receipt of an end of a first conduit section 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -5 in a second conduit section whereby fitted in an annular space defined between said end and said second section is a seal a radially inner sealing portion of which abuts an outer face of said end and a radially outer sealing portion of which abuts an inner face of the second section, such that sealing is effected in the annular space, the radially inner sealing 5 portion comprising an annular lip which projects axially beyond the radially outer sealing portion to be surrounded by pressurised fluid in the annular space and thereby forced against said inner face. Preferably, the method comprises fitting the seal within the second section then effecting 10 relative axial movement between the first and second sections such that said end is received in the second section whereby the radially inner sealing portion abuts the outer face of the end and said sealing is thus effected. The invention will now be described, by way of non-limiting example only, with reference 15 to the accompanying drawings, in which: Figure 1 is a first perspective view of a seal according to a preferred embodiment of the invention; Figure 2 is a second perspective view of the seal; Figure 3 is a side view of the seal; 20 Figure 4 is an axial cross-sectional view of the seal; Figure 5 is an axial cross-sectional view schematically depicting joining of two parts to form the seal; Figures 6 to 8 show stages in the formation of a conduit assembly comprising a pipe, a socket and the seal, wherein the seal effects sealing between the pipe and socket, in 25 accordance with a preferred embodiment of the invention; Figure 9 is a view of detail A in Figure 8 and shows the manner in which fluid in the conduit assembly engages the seal; and Figure 10 is a cross-sectional view which corresponds to Figure 4 and shows exemplary dimensions of the seal. 30 An annular rubber seal 1 according to a preferred embodiment of the present invention is 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -6 shown in Figures 1 to 3. The seal 1 is used, referring to Figures 6 to 9, to effect sealing between first and second sections in a fluid conduit which in the example described and illustrated comprise a pipe 3 and a socket 5 into which an end of the pipe 3 is received and via which the pipe 3 may be interconnected with another pipe (not shown) in the conduit. 5 The pipe 3 is formed from PVC, preferably PVC-O, though may, without departure from the invention, be formed from alternative PVC formulations (e.g., PVC-U or PVC-M) or metal (e.g., ductile iron). Also, the socket 5 may be replaced with an alternative member into which the pipe end is received such that the seal effects sealing between the pipe end and the member, such as an alternative form of fitting or a section of pipe having an inner 10 diameter greater than the outer diameter of the pipe 3. The socket 5 is formed of metal. The seal 1, when in situ, as shown in Figure 8, occupies an annular space 4 defined between the end of the pipe 3 and the socket 5, and, referring to Figures 1 to 3 includes a radially outer sealing portion 7 which comprises a radially outwardly facing, 15 circumferentially extending face 8 the axial cross-sectional profile of which is straight throughout and aligned with the central axis of the seal 1. The surface 8 is arranged so as to abut a radially inwardly facing circumferential surface 9 in the socket 5 whereby a seal is formed between the abutting surfaces when the seal 1 is in situ. The seal 1 further includes a radially inner sealing portion 11, comprising a radially inner surface 12 arranged 20 so as to abut an outer circumferential surface 13 of the pipe 3 whereby a seal is formed at the interface between the seal 1 and the pipe 3. The radially inner sealing portion 11 is configured with an annular lip 14 which projects beyond the radially outer sealing portion 7 and thereby defines an axially endmost extent of the seal 1. The entirety of the radially inner circumferential surface of the ring 1, including the surface 12, has an axial 25 cross-sectional profile which is angled with respect to the central axis of the seal 1, whereby, referring also to Figure 4, a tapered opening 15 is defined through the seal 1 to facilitate insertion of the pipe end through the seal 1, as will be described in further detail later. 30 The seal 1 is formed with an axially opening annular cavity 17, which promotes sealing in a manner which will be described later, the cavity 17 being positioned so as to define a 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -7 proximal portion of the lip 14 and such that the outer sealing portion 7 comprises an axially projecting lip 21. The seal 1 is additionally configured with a circumferentially extending, radially outwardly 5 opening groove or channel 19 which is arranged to engage a circumferentially extending, radially inwardly projecting bead formed in the socket 5 whereby the seal 1 is axially retained in a manner which will be described in further detail later. The seal 1 comprises two sections which are separately formed and bonded together 10 (preferably via vulcanisation), those sections comprising a first section 2A, which has a hardness of about 85 Shore A, and a second section 2B, which has a hardness of about 55 Shore A, the latter section defining the sealing portions of the seal 1. The section 2B is configured so as to define a substantially solid annular body region 10 15 extending from the surface 8 to the surface 12 so as to be compressed radially between the pipe 3 and socket 11 when the sealing is effected, thereby defining a reliable compression bridge which contributes to the sealing. The body region 10 defines a generally axially facing side surface 18 of the cavity 17 at an end thereof which is opposite to an end thereof at which it opens axially, the side surface 18 having a radial length which, referring to 20 Figure 10, is at least twice the thickness of the annular lip 14. The side surface 18 is substantially perpendicular to the central axis of the seal 1. In the example shown, the pipe 3 is a DN100 pipe and the seal 1 (in its relaxed condition), referring to Figure 10, has an outer diameter of about 14.5cm, and a minimum inner 25 diameter (at the tip of the lip 14) of about 11cm. The lip 14 has a thickness of about 0.25cm and projects a distance of about 0.55cm. Referring also to Figure 4, the body region 18 has an average radial length LR of about 1.3cm and an axial length LA of about 0.5cm. 30 The side surface 18 has a radial length of about 1cm. The body region 10 has an average radial length of about 1.3cm to about 1.4cm 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -8 Assembly of the conduit, which in the present example is an underground water mains conduit, whereby to effect sealing, via the seal 1, between the pipe 3 and fitting 5, will now be described. 5 Firstly, referring to Figure 6, the seal 1 is positioned in the socket 5 in a manner such that the bead 20 is received in the groove 19. Relative axial movement between the pipe 3 and socket 5 is then effected whereby the end of the pipe 3 is introduced into the end of the socket 5 and received through the tapered opening 15 in the seal 1, as shown in Figure 7. 10 While the pipe 3 is being so received, it exerts a radially outward force against the radially inner circumferential face of the seal 1, whereby, referring also to Figure 8, the sealing surface 12 aligns with and presses tightly against the surface 13, thus forming a seal therewith, and the surface 8 is pressed tightly against the surface 9 to form a seal therewith. Abutment between the bead 20 and a shoulder 22 defined by the groove 19 retains the 15 seal 1 axially during insertion of the pipe 3. The greater hardness of the first section 2A, which section includes the shoulder 22, promotes reliable engagement between the shoulder 22 and the groove 19. Referring to Figure 9, when fluid flows through the conduit, in either direction, pressurised 20 fluid occupying the annular space 4, including the cavity 17, forces the lip 14 against the pipe 3, enhancing sealing integrity. The lip 14, owing to its flexibility and its being sufficiently thin relative to the body region 10, will conform to the transverse cross-sectional exterior profile of the pipe 3 even if there is a degree of angular irregularity in that profile, resulting from ovality or other distortion, and/or a degree of misalignment 25 between the central axes of the pipe 3 and the socket 5. Also, fluid in the cavity 17 forces the lip 21 of the radially outer sealing portion 7 against the radially inner surface 9 of the socket 5, enhancing sealing. The cavity 17 functions as a domed compression pocket which uniformly distributes internal pressure, forcing the sealing surface portions of the lips 14 and 21 against the pipe 3 and socket 5 respectively. 30 Because fluid pressure contributes appreciably to the sealing effected by the seal 1, as l: \am\Interwoven\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 -9 described above, the body region 10 can (and does) have a relatively small axial length, whereby the amount of rubber which must be compressed/deformed when the pipe end is received through the seal 1 is, correspondingly, less, so that resistance to the receipt is reduced that the receipt thus facilitated. More particularly, that axial length, which is the 5 distance between the face 18 and the face of the section 2B via which that section is bonded to the section 2A can be (and is) less than the distance between the sealing portion sealing surfaces when the seal 1 is in situ, and more particularly is no more than about half of that distance. 10 While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. It will be apparent to a person skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above described 15 exemplary embodiments. Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps 20 but not the exclusion of any other integer or step or group of integers or steps.

Claims (35)

1. An elastomeric seal for sealing between first and second sections of a fluid conduit in which an end of the first section is received in the second section whereby an annular 5 space is defined between said end and said second section, the seal comprising a radially inner sealing portion receivable against an outer face of said end and a radially outer sealing portion receivable against an inner face of the second section, whereby sealing is effected in the annular space, wherein the radially inner sealing portion comprises an annular lip which projects generally axially beyond the radially outer sealing portion. 10

2. A seal according to claim 1, wherein said annular lip is of substantially uniform thickness along its length.

3. A seal according to claim 1 or 2, being configured with an annular cavity a radially 15 inner wall of which is defined by a proximal portion of the lip, the cavity being radially inward of the radially outer sealing portion and opening axially so as to be occupied by pressurised fluid in the annular space.

4. A seal according to any one of the preceding claims, wherein the annular cavity has 20 a generally axially facing side surface at an end thereof which is opposite to an end thereof at which it opens axially.

5. A seal according to claim 4, wherein the side surface has a radial length at least twice the thickness of said annular lip. 25

6. A seal according to claim 5, wherein said radial length is two to four times the thickness of said annular lip.

7. A seal according to any one of claims 4 to 6, wherein said side surface comprises a 30 face which is substantially perpendicular to the central axis of the seal. 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 - 11

8. A seal according to any one of the preceding claims, wherein the radially outer sealing portion comprises a circumferential lip which projects to define a radially outer wall of the cavity, whereby to be forced against the inner face of the second section by pressurised fluid occupying the cavity. 5

9. A seal according to any one of the preceding claims, wherein the radially outer sealing portion comprises a sealing face which has a substantially straight axial cross-sectional profile.

10 10. A seal according to claim 9, wherein said profile is aligned with a central axis of the seal.

11. A seal according to any one of the preceding claims, wherein the radially inner sealing portion comprises a sealing face which has a substantially straight axial 15 cross-sectional profile.

12. A seal according to claim 11, wherein said axial cross-sectional profile of the sealing face of the radially inner sealing portion is angled with respect to a central axis of the seal whereby an opening defined through the seal is tapered to facilitate fitting of the 20 seal to the first section.

13. A seal according to any one of the preceding claims, including a substantially solid annular body region extending from a sealing face of the radially inner sealing portion to a sealing face of the radially outer sealing portion so as to be compressed when said sealing 25 is effected whereby to urge the radially inner sealing portion and radially outer sealing portion against said outer face and said inner face respectively.

14. A seal according to claim 13, wherein the body region defines a proximal section of the radially inner sealing portion. 30

15. A seal according to claim 13 or 14, wherein said radially outer sealing portion 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 - 12 comprises said circumferential lip and said body region defines a proximal section of the radially outer sealing portion.

16. A seal according to claim 15, wherein a radial length of the body region is at least 5 twice an axial length of the body region.

17. A seal according to claim 16, wherein said radial length is two to three times the axial length. 10

18. A seal according to any one of the preceding claims, wherein an axial end section of the seal which comprises the sealing portions includes said body region.

19. A seal according to any one of the preceding claims, which is configured with a retaining formation engageable with a complementary retaining formation with which the 15 second conduit section is configured so as to be located within the second section and restrained from axial displacement relative thereto during insertion of said end into the second conduit section.

20. A seal according to claim 19, wherein the retaining formation thereof comprises a 20 circumferential shoulder receivable against a radially inwardly projecting circumferential bead defining the retaining formation of the second conduit section.

21. A seal according to claim 20, which is configured with a radially outwardly opening circumferential groove which defines the shoulder and is arranged to receive the 25 bead.

22. A seal according to claim 21, wherein an axial end section thereof which comprises said shoulder has a hardness which is greater than a hardness of an axial end section of the seal which comprises the sealing portions. 30

23. A seal according to claim 22, wherein the section comprising the shoulder has a 1: \azm\Interwoen\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 - 13 hardness of about 70 Shore A to about 100 Shore A and the section comprising the sealing portions has a hardness 45 Shore A to about 60 Shore A.

24. A seal according to claim 23, wherein the section comprising the shoulder has a 5 hardness of about 80 Shore A to about 90 Shore A and the section comprising the sealing portions has a hardness of about 50 Shore A to about 55 Shore A.

25. A fluid conduit comprising first and second sections, an end of the first section being received in the second section whereby an annular space is defined between said end 10 and said second section, and an elastomeric seal according to any one of the preceding claims, wherein the radially inner sealing portion of the seal is received against an outer face of said end and the radially outer sealing portion of the seal is received against an inner face of the second section, whereby sealing is effected in the annular space, the annular lip being arranged so as to be surrounded by pressurised fluid in the annular space 15 and thereby forced against said inner face.

26. A fluid conduit according to claim 25, wherein the first conduit section comprises plastic pipe. 20

27. A fluid conduit according to claim 26, wherein the plastic is polyvinylchloride (PVC).

28. A fluid conduit according to claim 27, wherein the plastic is PVC-0. 25

29. A fluid conduit according to claim 25, wherein first conduit section comprises ductile iron pipe.

30. A fluid conduit according to any one of claims 25 to 29, wherein the second conduit section is defined by a fitting. 30

31. A fluid conduit according to any one of claims 25 to 30, wherein the second l: \am\Interwoven\NRPortbl\DCC\AZM\5071155 l.doc-12 04/2013 - 14 conduit section comprises a socket.

32. A fluid conduit according to any one of claims 25 to 31, wherein the second conduit section is metal. 5

33. A method of assembling a fluid conduit, comprising effecting receipt of an end of a first conduit section in a second conduit section whereby fitted in an annular space defined between said end and said second section is a seal according to any one of claims 1 to 24, the radially inner sealing portion of which abuts an outer face of said end and the radially 10 outer sealing portion of which abuts an inner face of the second section, such that sealing is effected in the annular space, the annular lip being arranged so as to be surrounded by pressurised fluid in the annular space and thereby forced against said inner face.

34. A method according to claim 33, comprising fitting the seal within the second 15 section then effecting relative axial movement between the first and second sections such that said end is received in the second section whereby the radially inner sealing portion abuts the outer face of the end and said sealing is thus effected.

35. A seal substantially as hereinbefore described with reference to the accompanying 20 drawings.