AU2008101322A4

AU2008101322A4 - An expansion joint

Info

Publication number: AU2008101322A4
Application number: AU2008101322A
Authority: AU
Inventors: Andrew Hobbs
Original assignee: Plastec Australia Pty Ltd
Current assignee: Plastec Australia Pty Ltd
Priority date: 2007-10-12
Filing date: 2008-07-03
Publication date: 2013-10-03
Anticipated expiration: 2016-07-03
Also published as: AU2008202935A1

Abstract

An expansion joint 1 for coupling two conduits to each is disclosed. The expansion joint 1 includes an outer sleeve 3 defining inner and outer sleeve surfaces 10, 8 5 extending between opposed ends 5, 7. The outer sleeve 3 includes an outer sleeve stop formation 9 projecting inward that is formed integrally with the outer sleeve 3. The joint 1 also includes an inner sleeve 4 slidably received within said outer sleeve 3 defining inner and outer surfaces 34, 36, and an inner sleeve stop formation 37 projecting out there from that is formed integrally with the inner 10 sleeve. The inner sleeve stop formation 37 is sized to interfere with the outer sleeve stop formation 9 to limit movement of the inner sleeve 4 in an axial direction. The joint 1 includes an outer sleeve insert 17 that is snugly received within the outer sleeve 3 and permanently fixed thereto, which is also sized to interfere with said inner sleeve stop formation 37. Thus the assembly which may 15 be manufactured in a few separate moulding steps yields a joint 1 that resists being pulled part by a user. FIG. 2 FOR PUBLICATION

Description

1 AN EXPANSION JOINT FIELD OF THE INVENTION 5 This invention relates to an expansion joint for coupling two conduits having flow passages to each other such that the conduits are in flow communication with each other. This invention also extends to an inner sleeve for an expansion joint and a method of manufacturing an expansion valve and a pipe line assembly including an expansion valve. 10 This invention relates particularly but not exclusively to an expansion joint for coupling two conduits that are subterranean plumbing pipes of circular cross section to each other, such that the pipes can move relative to each other in an axial direction at least to some extent while still preserving the integrity and 15 functioning of the pipeline. In particular the pipes may be water pipes made of plastics material used in a domestic setting on or around domestic dwelling structures. It will therefore be convenient to hereinafter describe this invention with reference to this example application. However at the same time it is to be clearly understood that the invention is capable of other applications. 20 BACKGROUND TO THE INVENTION A pipe which is located underneath the ground is a well known contrivance in the plumbing art. Such pipes can be used to convey water from a mains pipe line to a 25 discrete water delivery point. Further such pipes can also be used to convey waste water away from a house to a main, e.g. a sewerage main or a storm water main, which drains water away from the dwelling. In many subterranean environments significant earth movements may take place. 30 For example these may be due to changes in moisture levels within the earth, heaving clays, and also change in temperatures within the soil. When earth 2 movements such as these take place they can impose forces on a pipeline received within the earth. Clearly therefore it would be advantageous if an expansion joint could be devised 5 so that a pipeline that was buried within the soil had an ability to accommodate movements in the surrounding earth and could lengthen or shorten in an axial direction while still coupling the two conduits together in a sealing fashion. SUMMARY OF THE INVENTION 10 According to one aspect of this invention there is provided an expansion joint for coupling two conduits to each other in flow communication with each other, the expansion joint including: 15 an outer sleeve defining an inner sleeve surface and an outer sleeve surface extending between one end and an opposed end, and including an outer sleeve stop formation projecting inward from the inner surface thereof; and an inner sleeve that is slidably received within said outer sleeve, the inner 20 sleeve defining an outer surface and an inner surface, and an inner sleeve stop formation projecting outward away from the outer surface thereof, the inner sleeve stop formation being sized to interfere with said outer sleeve stop formation when the inner sleeve is slid in an axial direction thereby to limit movement of the inner sleeve in an axial direction. 25 The outer sleeve stop formation projecting inward from the inner surface thereof may be formed integrally with the outer sleeve. Similarly the outwardly extending inner sleeve stop formation may also be formed integrally with the inner sleeve. 30 The expansion joint may further include an outer sleeve insert comprising an insert body defining an inner surface and an outer surface, and the outer sleeve insert 3 body may be sized and configured such that it can be snugly received within the outer sleeve. Thus the expansion joint comprises an outer sleeve having an outer sleeve stop 5 formation formed integrally therewith and the inner sleeve has an inner sleeve stop formation that is formed integrally therewith. By forming said outer sleeve stop formation and said inner sleeve stop formation integral with their associated outer or inner sleeve as the case may be, the number of forming operations to form the basic components for the expansion joint is reduced. 10 The insert body may define an insert body stop formation that is positioned radially inward of the inner surface of the outer sleeve, and the insert body stop formation, like said outer sleeve stop formation, may be sized to interfere with said inner sleeve stop formation. 15 The outer sleeve stop formation may be positioned towards one end of the outer sleeve, e.g. adjacent said one end thereof. Further the insert received within the outer sleeve may be positioned adjacent an opposite end of the sleeve to the outer sleeve stop formation. 20 The insert body may be permanently fixed to the outer sleeve. The insert body may resist the inner sleeve from being detached from the outer sleeve whereby to form a single joint assembly that cannot be pulled apart by a user. 25 The outer sleeve stop formation may project inward from the inner surface of the outer sleeve, and the stop formation on the insert body may be spaced away from said outer sleeve stop formation in the longitudinal direction of the outer sleeve. The outer sleeve may have a substantially circular cylindrical configuration, and 30 the outer sleeve stop formation may be an annular stop formation that extends substantially fully around the circumference of the inner surface of the outer sleeve.

4 The outer sleeve stop formation may be formed integrally with the outer sleeve in a single injection moulding operation. Further the outer sleeve stop formation may be positioned adjacent one end thereof and the insert body may be positioned 5 adjacent the other end of the outer sleeve. The inner sleeve may have a substantially circular cylindrical configuration, and the inner sleeve stop formation may be an annular stop formation that projects radially outward away from the inner sleeve around the full circumference thereof. 10 The inner sleeve stop formation may be positioned adjacent one end of the inner sleeve. The inner sleeve stop formation may also be formed integrally with the inner sleeve in a single injection moulding operation. The inner sleeve may include a seal support on which a seal can be mounted, and 15 the inner sleeve may also include a seal mounted on the seal support. The seal support and the seal may be sized so that the seal sealingly bears and rubs against the inner surface of the outer sleeve when mounted on the seal support. The inner sleeve stop formation on the inner sleeve, described above, may also 20 form at least part of the seal support. In one form of the invention the seal support may comprise two axially spaced circumferentially extending ribs that are axially spaced apart from each other, and one of said ribs may form said inner sleeve stop formation. The seal may be mounted on the seal support by being sandwiched between the two ribs that are spaced a small distance apart from 25 each other. The ribs may define a space between them of 5 to 15 mm. The seal may be sandwiched in the space between the two ribs where it is held in position by an interference fit. The seal may be a sealing ring that extends circumferentially around the inner 30 sleeve, e.g. a rubber sealing O-ring or a ring having a substantially rectangular cross section with a significantly greater cross sectional area and thereby a greater seal contact area than an O-ring.

5 The outer sleeve stop formation may be positioned towards one end of the inner sleeve, e.g. adjacent one end of the inner sleeve. Correspondingly the seal which is mounted on the seal support, and part of which forms the outer sleeve stop 5 formation, may also be positioned adjacent one end of the inner sleeve. The outer sleeve may include a sleeve wall, e.g. of substantially cylindrical configuration. The outer sleeve stop formation may be formed by a section of the outer sleeve wall that is formed of a reduced radius relative to the rest of the 10 sleeve wall to form said outer sleeve stop formation. The section of the outer sleeve that is formed of reduced radius may comprise a section of the sleeve that tapers radially inward in an axially extending direction. The outer sleeve stop formation may further include a cylindrical section of smaller 15 radius than the main body of the outer sleeve at the end of the tapered section that is of reduced radius, .e.g. at the end that is remote from the main body of the outer sleeve. The outer sleeve stop formation formed by the tapering section of the outer sleeve 20 may have a square internal shoulder, e.g. that extends orthogonally to the longitudinal axis of the outer sleeve, to provide a complementary abutment surface against which the outer surface of the seal support formation can abut. The stop formation on the outer sleeve may be positioned towards one end 25 thereof, and the reduced radius cylindrical section may form said one end of the outer sleeve. The outer diameter of the inner sleeve may be sized such that it can be received within said outer sleeve stop formation with a working clearance, so that the outer 30 sleeve stop formation permits sliding displacement of the inner sleeve relative to the outer sleeve and also guides this displacement.

6 The outer sleeve may have a greater diameter than the diameter of adjacent pipes to which the expansion joint is to be coupled. The outer sleeve may also have a plurality of circumferentially extending ribs projecting outward therefrom along the axial length of the outer sleeve. 5 The insert body may be sized to be snugly received within the outer sleeve to facilitate a face to face fixing of an outer surface of the insert body to the inner surface of the outer sleeve. Thus the body of the outer sleeve insert may be substantially cylindrical to complement the cylindrical inner surface of the outer 10 sleeve towards said opposed end. The insert may be sealingly mounted to the outer sleeve. That is the outer surface of the insert may be permanently and sealingly adhered to the inner surface of the outer sleeve, e.g. by means of solvent welding, adhesive or the like. 15 The insert body may have an inner diameter that substantially corresponds with the diameter of the outer surface of the inner sleeve. The inner diameter of the insert body may optionally taper radially inwardly in an axial direction to assist coupling thereof to an adjacent pipe section by means of an interference fit. 20 The insert body may further include an inward pipe stop formation in the form of a radially inwardly extending annular shoulder for limiting the extent of travel of an adjacent pipe section into the insert. 25 For example the inward pipe stop formation may be in the form of an annular shoulder that extends radially in from the inner surface of the insert, e.g. around the circumference of the inner surface of the insert. This provides a stop or locating formation against which an end of a pipe, e.g. to which the joint is coupled, can abut when it is inserted into the insert. 30 7 The insert body may further include an outward locating formation in the form of an annular rib projecting radially outwardly away from the insert body for locating the insert body in position along the longitudinal length of the outer sleeve. 5 The outward locating formation may comprise a formation projecting radially outwardly away from the outer surface of the body of the insert. The outward or outer sleeve locating formation may be in the form of a circumferential flange positioned towards the opposite end of the insert body to the pipe locating formation. 10 The outer sleeve insert may have an inner surface having a diameter that is sized to substantially correspond with the diameter of the outer surface of the inner sleeve. This way an end section of adjacent pipe having the same outer diameter as the inner sleeve can be received within the outer sleeve insert. If the diameter 15 of the adjacent pipe is less than that of the inner surface of the outer sleeve insert an adapter can be used, e.g. a reducing bush. The end section of another adjacent pipe extending away from the joint in an opposite direction can be mounted on an end of the inner sleeve that projects out 20 of the inner sleeve. The inner and outer sleeve and the outer sleeve insert may be formed of plastics material, e.g. polyethylene, or any other plastic having appropriate mechanical strength properties. The different components may be made of the same plastics 25 material or a different plastics material. According to another aspect of the invention in an expansion joint for coupling two conduits to each other in flow communication with each other, in which an outer sleeve defines an inner surface and an outer surface extending between one end 30 and an opposed end with an outer sleeve stop formation projecting inward from an inner end thereof, and in which an inner sleeve is slidably received within said outer sleeve, 8 wherein the inner sleeve includes an inner sleeve body defining an outer surface and an inner surface, and an outwardly extending inner sleeve stop formation projecting outward away from the outer surface thereof, and the inner sleeve stop 5 formation is sized to interfere with said one stop formation when the inner sleeve is slid in an axial direction thereby to limit movement of the inner sleeve in an axial direction. The outwardly extending inner sleeve stop formation may be formed integrally with 10 the inner sleeve. The inner sleeve may have a substantially circular cylindrical configuration. Further the inner sleeve stop formation may have an annular stop formation that projects outward away from the inner sleeve around the full circumference thereof. The 15 inner sleeve stop formation may be positioned adjacent one end of the inner sleeve. The inner sleeve stop formation may be formed integrally with the inner sleeve in a single injection moulding operation. 20 The inner sleeve may include a seal support and the inner sleeve may further include a seal mounted on the seal support. In one form the inner sleeve stop formation on the inner sleeve also forms the seal support. The inner sleeve stop formation may comprise two axially spaced circumferentially extending ribs that 25 are axially spaced apart from each other and the seal may be sandwiched in the space defined between the two ribs. The inner sleeve may include any one or more of the features of the inner sleeve as defined in the first aspect of the invention above. 30 According to another aspect of this invention there is provided a method of manufacturing an expansion valve, including: 9 forming an outer sleeve having an integral outer sleeve stop formation projecting radially inward therefrom in a moulding operation; 5 forming an inner sleeve having an outward projecting inner sleeve stop formation projecting radially outward therefrom in another moulding operation; and placing the inner sleeve through an end of the outer sleeve such that the inner sleeve stop formation is received within the outer sleeve, and the inner 10 sleeve projects out through one end of the outer sleeve. The method may further include forming an outer sleeve insert in yet another moulding operation, and then inserting the outer sleeve insert into the other end of the outer sleeve and fixing it to the outer sleeve whereby to form an assembled 15 expansion joint that cannot be pulled apart. The method may include permanently fixing the outer sleeve onto the insert for the outer sleeve by adhesive or by solvent welding. 20 The method may further include forming the inner sleeve stop formation such that it includes two axially spaced circumferential ribs extending around the inner sleeve forming a seal support formation. The method may further include mounting a circumferential seal on the seal support. 25 The outer sleeve and the outer sleeve stop formation may be formed in a single injection moulding operation. The inner sleeve and the inner sleeve stop formation may also be formed in another single injection moulding operation as may the outer sleeve insert. 30 The method may further include any one or more of the method steps defined in the detailed description of the invention.

10 This invention also extends to a pipeline assembly including a plurality of pipe sections and at least one expansion joint as defined above in the first aspect of the invention coupled in line with two of the pipe sections. 5 The expansion joint may include any one or more of the optional features of the expansion joint described above according to the first aspect of the invention. This invention also extends to a method of forming a pipe line assembly that is capable of expansion in an axial direction, including: 10 providing two pipe sections having adjacent ends that are axially spaced apart from each other; inserting an expansion joint as defined above according to the first aspect 15 of the invention, into the space between the ends of the pipe sections; expanding the expansion joint so that it fills the space between the ends of the pipe sections; and 20 operatively connecting the expansion joint at each end to the adjacent pipe sections. The expansion joint may include an outer sleeve insert and one pipe section may be inserted into an open end of the outer sleeve insert. The pipe section may be 25 received within the socket formed by the outer sleeve insert. The pipe section may be solvent welded to the outer sleeve insert. The other pipe section may form a socket that is passed over and around an end of the inner sleeve. 30 The expansion joint may be permanently connected to the adjacent pipe sections, e.g. by solvent welding, adhesive or the like. The other pipe section may be 11 solvent welded to the inner sleeve. Specifically the socket may be solvent welded to an end region of the other pipe section. The expansion joint may include any one or more of the optional features of the 5 expansion joint described above according to the first aspect of the invention. DETAILED DESCRIPTION OF THE INVENTION An expansion joint in accordance with this invention may manifest itself in a variety 10 of forms. It will therefore be convenient to hereinafter describe at least one embodiment of the invention in detail with reference to the following drawings. The purpose of providing this detailed description is to instruct persons having an interest in the subject matter of the invention how to carry the invention into practical effect. However it is to be clearly understood that the specific nature of 15 this detailed description does not supersede the generality of the preceding broad description. In the drawings: Fig. 1 is an exploded perspective view of an expansion joint in accordance with one embodiment of the invention; 20 Fig. 2 is a sectional side view of the expansion joint of Fig. 1; Fig. 3 is an external side view of the expansion joint of Fig. 1; 25 Fig. 4 is an end view of the expansion joint of Fig. 1; Fig. 5 is an external three dimensional view of the assembled expansion joint of Fig. 1; and 30 Fig. 6 is a sectional side view of a pipeline comprising two pipe sections coupled to each other by means of an expansion joint like that in Fig. 1.

12 In Fig. 1 reference numeral 1 refers generally to an expansion joint in accordance with the invention. The expansion joint 1 comprises broadly an outer sleeve 3 and an inner sleeve 4 a 5 portion of which is received within the outer sleeve 3. The outer sleeve 3 comprises a sleeve wall 6 having one end 5 and an opposed end 7. The sleeve wall defines an inner surface 10 and an outer surface 8. The outer sleeve 3 also includes an outer sleeve stop formation (or inward extending 10 stop formation) 9 at the end 5. The outer sleeve stop formation 9 is formed by an end region 12 on the sleeve wall 6 that is of reduced radius and extends inward relative to the rest of the sleeve wall 6. In the illustrated embodiment the end region 12 comprises a frusto 15 conical or inwardly tapering section 13 and then a cylindrical section 15 adjacent the frusto-conical section 13 defining the end of the outer sleeve 3. The expansion valve 1 further includes an outer sleeve insert 17 comprising a broadly cylindrical body of short axial length that is sized to be snugly received 20 within the wall of the outer sleeve 3 such that it can be fixed thereto, e.g. by solvent welding, adhesive or the like. The insert body 17 defines an inner surface 16 and an outer surface 18 that is sized to substantially complement the diameter of the inner surface 10 of the outer 25 sleeve 3. This enables the insert 17 to be snugly received within the outer sleeve 3. The insert 17 defines a further stop formation 11 that effectively projects radially inward from the inner surface 6 of the outer sleeve 8. The further stop formation 11, like said one outer sleeve stop formation 9 is sized to interfere with an inner sleeve (or outwardly projecting) stop formation on the inner sleeve 4. 30 The outer sleeve insert 17 has an inner surface 16 and an outer surface 18. The inner surface 16 has a diameter that is sized to substantially complement the outer 13 surface of the inner sleeve 4, e.g. the inner sleeve 4, apart from the stop formation 11, may be sized such that it could be received within the outer sleeve insert 17. The outer sleeve insert 17 further includes a pipe locating formation 19 that is of 5 smaller diameter than the diameter of the inner surface 16 of the insert 17. The pipe locating formation 19 extends radially inward from the inner surface 16 of the insert 17. This provides a locating formation 19 against which an end of a pipe, e.g. to which the joint is coupled, can abut when it is inserted into the insert 17. 10 In the illustrated embodiment the pipe locating formation 19 is in the form of an annular shoulder at one end of the insert 17 that extends radially in from the inner surface 16 of the insert 17 a short distance. The insert 17 further includes an outer sleeve locating formation 22 for mounting 15 over an end of the outer sleeve 3 thereby to locate the insert longitudinally on the outer sleeve 3. In the illustrated embodiment the outer sleeve locating formation 22 comprises a formation in the form of a circumferential flange projecting radially outwardly away from the outer surface 18 of the outer sleeve insert 17. The outer sleeve locating formation 22 is positioned towards the opposite end of the insert 20 body 17 to the pipe locating formation 22. The outer surface of the insert 17 is sealingly adhered to the inner surface 6 of the outer sleeve 3, by means of solvent welding, adhesive or the like. 25 The cylindrical insert 17 is sized to receive an end section of an adjacent pipe to which the expansion joint 1 is to be coupled therein. As such the inner diameter of the stop formation 11 may complement the outer diameter of the adjacent pipe to which it is to be coupled and also made to correspond to the outer diameter of the internal sleeve 4. 30 Further the outer sleeve 3 has a plurality of axially spaced circumferential rings 25 on its outer surface 8 to assist a user with gripping the outer sleeve 3.

14 The inner sleeve 4 comprises an inner sleeve wall 31 having one end 33 that is received within the outer sleeve and an opposed end 35 that is external to the outer sleeve 3. The wall has an inner surface 34 and an outer surface 36. 5 The inner sleeve 4 has a radius that is less than the radius of the outer sleeve 3 and may correspond to the diameter of the pipe sections to which the expansion joint 1 is coupled at each end. 10 The inner sleeve 4 includes an inner sleeve (or outward projecting) stop formation 37 at the end 33 thereof. The inner sleeve stop formation 37 projects radially outward from the outer surface 36 of the inner sleeve wall and is sized to be received with a high tolerance sliding clearance within the outer sleeve wall 6 such that the inner sleeve 4 can slide relative to the wall of the outer sleeve 3. In the 15 illustrated embodiment the inner sleeve stop formation 37 is in the form of a rib 43 that projects outward away from the outer surface 30 of the inner sleeve 4 around the circumference of the inner sleeve 4. The inner sleeve 4 also includes a seal support formation. The seal support 20 formation comprises the rib 43 described above forming the inner sleeve stop formation and a further similar rib 45 that projects outward away from the outer surface 36 of the inner sleeve 4 and extends around the circumference of the inner sleeve 4. The ribs 43 and 45 are axially spaced apart from each other by a short distance. 25 The inner sleeve 4 also includes a seal 41 mounted thereon. In the illustrated embodiment the seal comprises a sealing ring that is mounted on the sleeve 4 between the ribs 43, 45 with a tight friction fit or interference fit. The seal projects radially out beyond the ribs 43, 45 to seal against the wall 6 of the outer sleeve 3. 30 The outer sleeve 3 excluding the outer sleeve insert 17 is formed as an integral article by means of a moulding operation such as an injection moulding operation.

15 Thus the outer sleeve stop formation is formed integrally with the rest of the sleeve wall 6. Similarly the inner sleeve 4, including the rib 43 forming the inner sleeve stop 5 formation and part of the seal support formation and the rib 45 forming the other part of the seal support formation, is formed in a single injection moulding operation. The seal 41 is then placed in position sandwiched between the ribs 43, 45 one of which forms the inner sleeve stop formation of the inner sleeve 4. 10 The outer sleeve insert 17 is also formed separately from the rest of the outer sleeve 3 in a separate injection moulding operation. The expansion joint 1 is then assembled from the separately moulded components 3, 17, and 4 as follows. The inner sleeve 4 is passed through the end 7 of the 15 outer sleeve 3 so that the inner sleeve stop formation 37 on the inner sleeve 4 is positioned intermediate the ends 5, 7 of the outer sleeve 3 in an axial direction. The inner sleeve 4 projects out through the open end 5 of the outer sleeve 3 such that its end 35 is positioned outward of the sleeve 3. 20 Thereafter the insert 17 forming the outer sleeve stop formation 11 is mounted within the outer sleeve 3 adjacent the end 7 and is affixed thereto by solvent welding, adhesive or the like. This effectively holds the inner sleeve 4 mounted on the outer sleeve 3 because it cannot slide off the outer sleeve 3. This thereby completes the assembly of the expansion joint 1. 25 In use the expansion joint 1 is coupled to two pipes that are broadly arranged end to end with the joint 1 intermediate the adjacent ends of the pipes. A typical usage is shown in Fig 6 where the joint is coupled in line with a subterranean water pipe includes pipe sections 51, 53. 30 16 The joint 1 is moved to a retracted position by sliding the inner sleeve 4 into the outer sleeve 3 to the maximum extent. In this position the inner sleeve stop formation 37 on the inner sleeve 4 will be adjacent to the insert 17. 5 The joint 1 can then be lowered into position between the ends of the pipes 51, 53. One end of one pipe 53 will be inserted into the insert body 17 until the end of the pipe 53 abuts up against the inward shoulder 19 on the inner end of the body 17. Thereafter the expansion joint 1 can be moved part of the way to its fully extended position by sliding the inner sleeve 4 out of the outer sleeve 3 until it is correctly 10 positioned for attachment to the other pipe 51. In the illustrated embodiment the other pipe 51 has a flared end region defining a socket within which the end of the sleeve 4 is received. It will readily be appreciated by persons skilled in the art that there are many other ways in which the ends of the expansion joint 1 may be coupled to the adjacent pipe ends. 15 In its position underneath the ground the expansion joint 1 permits movement of the inner sleeve 4 relative to the outer sleeve 3 in an axial direction to accommodate earth movement and the like. This way shrinkage or expansion in the earth due to differing moisture levels and/or temperature changes can be 20 accommodated by the pipe and do not necessarily transmit consequent forces through to the pipe line. An advantage of the expansion joint described above with reference to the drawings is that a stop formation on the outer sleeve is formed integrally with the 25 outer sleeve in a single moulding operation. Consequently there is one less component to mould and this leads to a first saving in the manufacturing cost. A further advantage is that there is one less step in the assembly of the expansion valve because the outer sleeve stop formation is already integrally formed with the outer sleeve and therefore does not need to be attached thereto. This leads to a 30 further saving in the manufacturing cost.

17 A further advantage of the expansion valve described above with reference to the drawings is that the diameter of an inner surface of the integral outer sleeve stop formation can be of fine tolerance when it is formed integrally with the rest of the sleeve. Consequently the outer sleeve can receive the inner sleeve therein with a 5 sliding fit but with only a very small gap between the inner and outer sleeves. This resists the passage of dirt, soil and the like from the environment into the space defined between the inner and the outer sleeves. It will of course be realised that the above has been given only by way of 10 illustrative example of the invention and that all such modifications and variations thereto, as would be apparent to persons skilled in the art, are deemed to fall within the broad scope and ambit of the invention as is herein set forth.

Claims

1. An expansion joint for coupling two conduits to each other in flow communication with each other, the expansion joint including: 5 an outer sleeve defining an inner sleeve surface and an outer sleeve surface extending between one end and an opposed end, and including an outer sleeve stop formation projecting inward from the inner surface thereof; and 10 an inner sleeve that is slidably received within said outer sleeve, the inner sleeve defining an outer surface and an inner surface, and an inner sleeve stop formation projecting outward away from the outer surface thereof, the inner sleeve stop formation being sized to interfere with said inwardly extending outer sleeve stop formation when the inner sleeve is slid in an axial direction thereby to limit 15 movement of the inner sleeve in an axial direction.

2. An expansion joint according to claim 1, wherein said outer sleeve stop formation projecting inward from the inner surface thereof is formed integrally with the outer sleeve. 20

3. An expansion joint according to claim 1 or claim 2, wherein the outwardly extending inner sleeve stop formation is formed integrally with the inner sleeve.

4. An expansion joint according to any one of claims 1 to 3, further including 25 an outer sleeve insert comprising an insert body defining an inner surface and an outer surface, and wherein the outer sleeve insert body is snugly received within the outer sleeve.

5. An expansion joint according to claim 4, wherein the insert body defines an 30 insert body stop formation that is positioned radially inward of the inner surface of the outer sleeve, and wherein the insert body stop formation, like said outer sleeve stop formation, is sized to interfere with said inner sleeve stop formation. 19

6. An expansion joint according to claim 5, wherein the insert body is permanently fixed to the outer sleeve, and wherein the insert body resists the inner sleeve from being detached from the outer sleeve whereby to form a single 5 joint assembly that cannot be pulled apart by a user.

7. An expansion joint according to claim 5, wherein the outer sleeve stop formation projects inward from the inner surface of the outer sleeve, and wherein said inner sleeve stop formation on the insert body is spaced away from said outer 10 sleeve stop formation in the longitudinal direction of the outer sleeve.

8. An expansion joint according to any one of claims 1 to 7, wherein the outer sleeve has a substantially circular cylindrical configuration, and wherein said outer sleeve stop formation is an annular stop formation that extends substantially fully 15 around the circumference of the inner surface of the outer sleeve.

9. An expansion joint according to claim 8, wherein the outer sleeve stop formation is formed integrally with the outer sleeve in a single injection moulding operation. 20

10. An expansion joint according to any one of claims 1 to 9, wherein the outer sleeve stop formation is positioned adjacent one end thereof and wherein the insert body is positioned adjacent the other end of the outer sleeve. 25

11. An expansion joint according to claim 10, wherein the inner sleeve has a substantially circular cylindrical configuration, and wherein the inner sleeve stop formation is an annular stop formation that projects outward away from the inner sleeve around the full circumference thereof, and wherein the inner sleeve stop formation is positioned adjacent one end of the inner sleeve. 30 20

12. An expansion joint according to any one of claims 1 to 11, wherein the inner sleeve stop formation is formed integrally with the inner sleeve in a single injection moulding operation. 5

13. An expansion joint according to claim 12, wherein the inner sleeve includes a seal support on which a seal can be mounted.

14. An expansion joint according to claim 13, wherein the inner sleeve further includes a seal mounted on the seal support. 10

15. An expansion joint according to claim 14, wherein the inner sleeve stop formation on the inner sleeve also forms at least part of the seal support.

16. An expansion joint according to claim 15, wherein the seal support 15 comprises two axially spaced circumferentially extending ribs that are axially spaced apart from each other, one of said ribs forms said inner sleeve stop formation.

17. An expansion joint according to claim 16, wherein the seal is mounted on 20 the seal support by being sandwiched between the two ribs.

18. An expansion joint according to any one of claims 1 to 17, wherein the outer sleeve stop formation comprises a section of the outer sleeve that is formed of a reduced radius relative to the rest of the sleeve wall. 25

19. An expansion joint according to claim 18, wherein the section of the outer sleeve that is formed of reduced radius comprises a section of the sleeve that tapers radially inward in an axially extending direction. 30

20. An expansion joint according to claim 19, wherein the outer sleeve stop formation further includes a cylindrical section of smaller radius than the main body of the outer sleeve at the end of the tapered section that is of reduced radius. 21

21. An expansion joint according to any one of claims 1 to 20, wherein the outer diameter of the inner sleeve is sized such that it can be received within said outer sleeve stop formation with a working clearance, so that the outer sleeve stop 5 formation permits sliding displacement of the inner sleeve relative to the outer sleeve and also guides this displacement.

22. An expansion joint according to any one of claims 1 to 21, wherein the outer sleeve has a greater diameter than the diameter of adjacent pipes to which the 10 expansion joint is to be coupled, and wherein the outer sleeve has a plurality of circumferentially extending ribs projecting outward therefrom along the axial length of the outer sleeve.

23. An expansion joint according to claim 4, wherein the insert body is sized to 15 be snugly received within the outer sleeve to facilitate a face to face fixing of an outer surface of the insert body to the inner surface of the outer sleeve.

24. An expansion joint according to claim 1, wherein said insert body has an inner diameter that substantially corresponds with the diameter of the outer 20 surface of the inner sleeve, and wherein the inner diameter of the insert body tapers radially inwardly in an axial direction to assist coupling thereof to an adjacent pipe section by means of an interference fit.

25. An expansion joint according to claim 4, wherein the insert body further 25 includes an inward pipe stop formation in the form of a radially inwardly extending annular shoulder for limiting the extent of travel of an adjacent pipe section into the insert.

26. An expansion joint according to claim 25, wherein the insert body further 30 includes an outward locating formation in the form of an annular rib projecting radially outwardly away from the insert body for locating the insert body in position along the longitudinal length of the outer sleeve. 22

27. An inner sleeve for an expansion joint for coupling two conduits to each other in flow communication with each other, which expansion joint includes an outer sleeve defining an inner surface and an outer surface extending between 5 one end and an opposed end with an outer sleeve stop formation projecting inward from an inner end thereof, the inner sleeve including an inner sleeve body defining an outer surface and an inner surface, and an outwardly extending inner sleeve stop formation projecting outward away from the outer surface thereof, and the inner sleeve stop formation is sized to interfere with said one stop formation 10 when the inner sleeve is slid in an axial direction thereby to limit movement of the inner sleeve in an axial direction.

28. An inner sleeve according to claim 27, wherein the outwardly extending inner sleeve stop formation is formed integrally with the inner sleeve. 15

29. An inner sleeve according to claim 27 or claim 28, wherein the inner sleeve has a substantially circular cylindrical configuration, and wherein the inner sleeve stop formation is an annular stop formation that projects outward away from the inner sleeve around the full circumference thereof, and the inner sleeve stop 20 formation is positioned adjacent one end of the inner sleeve.

30. An inner sleeve according to claim 29, wherein the inner sleeve stop formation is formed integrally with the inner sleeve in a single injection moulding operation. 25

31. An inner sleeve according to claim 30, wherein the inner sleeve includes a seal support on which the seal is mounted.

32. An inner sleeve according to claim 31, wherein the inner sleeve further 30 includes a seal mounted on the seal support 23

33. An inner sleeve according to claim 32, wherein the inner sleeve stop formation on the inner sleeve also forms the seal support.

34. An inner sleeve according to claim 33, wherein the inner sleeve stop 5 formation comprises two axially spaced circumferentially extending ribs that are axially spaced apart from each other and wherein the seal is sandwiched in the space defined between the two ribs.

35. A method of manufacturing an expansion valve, including: 10 forming an outer sleeve having an integral outer sleeve stop formation projecting radially inward therefrom in a moulding operation; forming an inner sleeve having an outward projecting inner sleeve stop 15 formation projecting radially outward therefrom in another moulding operation; and placing the inner sleeve through an end of the outer sleeve such that the inner sleeve stop formation is received within the outer sleeve, and the inner sleeve projects out through one end of the outer sleeve. 20

36. A method according to claim 35, further including forming an outer sleeve insert in yet another moulding operation, and inserting the outer sleeve insert into the other end of the outer sleeve and fixing it to the outer sleeve whereby to form an assembled expansion joint that cannot be pulled apart. 25

37. A method according to claim 36, further including permanently fixing the outer sleeve onto the insert for the outer sleeve by adhesive or by solvent welding.

38. A method according to any of claims 35 to 37, further including forming the 30 inner sleeve stop formation such that it includes two axially spaced circumferential ribs extending around the inner sleeve forming a seal support formation. 24

39. A method according to claim 38, further including mounting a circumferential seal on the seal support.

40. A method according to any one of claims 35 to 39, wherein the outer sleeve 5 and the outer sleeve stop formation are formed in a single injection moulding operation, and the inner sleeve and the inner sleeve stop formation are formed in another single injection moulding operation.

41. An expansion joint for coupling two conduits to each other in flow 10 communication with each other substantially as herein described in the detailed description with reference to the drawings

42. A method of manufacturing an expansion valve substantially as herein described in the detailed description of the invention. 15