PIPE JOINTS

Abstract: A PVC joint between socket (22) and spigot ends (10) with coaxial spigot end locating means (21) and seal engaging surfaces to the socket (22). The joint being sealed against internal and external pressures by a seal having a sealing body portion (33) compressed between the spigot and socket with outwardly directed sealing fins (32, 34) attached thereto.

Description: "PIPE JOINTS" TECHNICAL FIELD OF THE INVENTION THIS INVENTION relates to pipes and more particularly to the means by which pipe lengths may be sealably joined one to another. BACKGROUND ART Extruded piping of materials such as PVC are produced for application in sewerage systems and in order to effect a sealed joint between two lengths, a rubber seal can be used to prevent the escape of the pipe*s contents, the seal being compressed between the outer surface of a spigot end and the inner surface of a socket end. In order to insert the spigot into a socket end with a seal in place, a locating recess to the inner socket surface is commonly provided. The socket end is formed as a larger diameter bell shaped region at the pipe end with a seal locating recess on the inner wall for receipt of the seal. Assembly involves the location of a seal in its seat and the pushing of a spigot end therepast, Usually lubricants are employed so as to enable insertion without twisting or displacement of the seal. Even with lubricants, the seal may be displaced. To date there is no effective means by which a joint between extruded pipes may be formed which will provide reliable seals given the range of conditions which may be experienced when laying pipes in trenches where dirt and grit is an ever present problem; where trenches may be underwater at various points; where twists may develop at the pipe joints; and where the infiltration pressures, where pipes are below the water table, are such that water may leak into the pipe system. In sewer systems, it is undesirable to allow infiltration of ground water which increases the load on the system. A further problem is the penetration of the system by plant roots past badly designed or fitted joints to eventually cause blockages of the system. The design of the system's seal and the construction of the mating ends is critical to the ability of the system to survive as well as being critical regarding ease with which the system may be made to operate. The other major area where pipe costs and effective pipe interconnection is a continuing problem is in provision of water mains for delivery of water to specific localities. Commonly employed are fibre reinforced concrete pipes which are proving undesir¬ able for a variety of factors. It would be desirable to employ PVC piping but a sealing means is required to resist internal pressures as well as external infiltration as might occur with tree roots whilst retaining ease of setting up and low costs. OUTLINE OF THE INVENTION It is an object of the present invention to provide a pipe joint which is applicable to the now common extruded pipes formed of plastic type materials such as PVC. It is a further object of the present invention to provide a pipe joint which provides enhanced assembly properties enabling a pipe system to be constructed with a higher degree of confidence in the integrity of the pipe joints than has herebefore been possible. It is a still further object of the present invention to provide a combination of socket and spigot end configurations which are more readily adapted to construction of a pipe system without the defects which may arise with other systems through joint movement during layup caused by movements of jointed pipes such that the effectiveness of the seal at that joint might otherwise be defective. It is another object of the present invention to provide a pipe joint and seal which is effective to seal a joint against internal and infiltration pressures. Other objects and advantages of the present invention will hereinafter become apparent. The present invention achieves its objects by the provision of a pipe joint which comprises mating socket and spigot end pieces, the spigot end being provided with a seal engaging outer surface, the socket end of a pipe forming a joint with said spigot end being provided with a spigot engaging portion which receives the spigot end therein to engage the spigot end and align it with said socket, the socket end piece being additionally formed with a seal engaging surface which engages said seal to compress said seal between said surface and the spigot end such that a spigot end carrying a seal thereon may be inserted into said socket to slide said seal along the inner seal engaging surface to a position whereat said spigot is sealably located within said spigot engaging portion of said socket. BRIEF DESCRIPTION OF THE DRAWINGS In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment thereof and wherein:- Fig. 1 is a sectional view illustrating the configuration of the socket and spigot pipe ends which may be mated in accordance with the teachings of the present invention to achieve a seal therebetween; Fig. 2 is a sectional view through a sealing ring which may be used in the pipe joint shown in Fig. 1; Fig. 3 is a sectional view illustrating the alternate configuration of socket and spigot pipe ends in accordance with the present inventio ; Fig. 4 is a sectional view of a seal and pipe combination in accordance with the present OMPI invention; Fig. 5 is a sectional view of another seal and pipe arrangement; and Fig. 6 is an alternate form of the invention to that shown in Figure 5. METHOD OF PERFORMANCE Fig. 1 shows the various structural aspects of the spigot and socket ends of two mated pipes in sectional view with the diameter of the pipe reduced in relation to its length to clearly show the various features of the joint. The spigot end of pipe 10 is shown with end 11 mated into the socket end of the mating pipe 20. The spigot end is provided with an outer groove 12 which is shaped to receive a locating portion of a sealing ring (not shown) which engages the inner surface of the socket end to be compressed between the inner and outer surfaces of the socket and spigot to achieve a seal therebetween. The groove 12 engaging with a locating portion of a sealing ring, locates the ring thereon as the seal and spigot are pushed into the socket. The actual position of the groove 12 relative to- the end 11 will be determined in accordance with various parameters such as the lengthwise exteiyt of the seal, the pe:rmissable axial joint movement built into the design and the extent of the socket lengthwise. The pipe 20, of Fig. 1, is fitted with a socket end opening with an outward flare 23 to receive, locate, and lead in the initially uncompressed seal on the spigot end as it is inserted into the socket. The flare 23 leads inwardly to a cylindrical seal engaging inner surface 22 which surrounds the spigot end and provides a gap therebetween into which an annular seal, seated in groove 12, may be fitted to sealingly engage thereagainst. The inner extent of surface 22 terminates in a spigot end engaging portion 21 into which end 11 of the spigot end is fitted so as to be axially aligned thereby during installation of the system. The alignment serves to offset unwanted twistings of the pipe axes, one to the other, which would differentially compress the sealing ring and contribute to possible failures of the seal. Once the system is properly bedded and backfilled, the problem is largely resolved, but during construction sideways displacements of the pipes can produce undesirable pressures on the seals. The portion 21 provides against this by locking the pipes. The extent, lengthwise, of the portion 21 must take account of normal pipe length contractions which occur during the time of layup such that the maximum contraction of length will leave sufficient engagement at this section to lock the pipes against sideways movement. Fig. 2 shows a sectional view through a sealing ring which is suitable for use with the pipe joint of the present invention. This ring comprises a locating portion 30 which fits into groove 12 on the spigot end to locate it in place during assembly. The ring is provided with a rearwardly tapered front end leading back to a body portion 33 which is provided with a rearwardly orientated, tapered fin 34 off the rearward top section thereof. The back of the ring is provided with a shoulder 35 over which the fin 34 is compressed in operation, and a rearwardly orientated, tapered tail 32. The front end 31 faces inwardly of the joint formed with the seal and the body portion 33 provides a seal by compression between the spigot and socket. The tapered ramp surfaces of the rear portion 32 and the fin 34 provide, in compression between the spigot and socket surfaces, surfaces which direct roots attempting to penetrate the seal away from the seal pipe interface into the V shaped recess over the shoulder beneath the fin and JϋϊϊX. OMPI so prevent violation of the seal. The two rearwardly directed fin structures 32 and 34 also serve to seal against liquid infiltration which can occur where the pipe joint is below the water table and external pressures are substantial. The external pressures serve to increase the interface pressures between the fin and pipe surfaces to enhance the seal. The forward body portion as shown tends to stabilise the seal against twisting and rolling forces during insertion of the spigot into the socket and the rearward disposition of the locating portion 30 ensures that the compression of the body portion 33 is not into the locating groove such that compressive forces are not lessened thereby. In Fig. 3 is shown an alternate mechanism for locating a seal between the spigot end 11 and the seal engaging inner surface 22. The groove 12 of Fig. 1 is not formed. An abutment 40 is provided against which internal pressures will push a seal (not shown) of the type previously described. The abutment 40 might simply be formed by a sleeve of the same material as that of pipe 10 welded or adhered thereto by any suitable means such as by epoxy type glues etc. This construction eliminates the need for a locating groove where its production might weaken the physical properties of the pipe. Fig. 4 shows an alternate form of seal which enables a seal to be fixed to pipe 10 as a permanent fixture so as to do away with the need of grooves and abutments as locating elements. The seal of Fig. 4 has the character of the earlier described seal except that its base 36 is flat and engaged over its length with pipe 10. In practice the seal may be vulcanised or otherwise adhered to the material of pipe 10 so as to be rigidly located thereon. Such a pipe end need only be slid into a mating spigot end to produce an effectively sealed pipe connection. In Figure 5 the pipe spigot end has an integrally formed abutment 41 against which a seal is pressed by internal pressures to stop it blowing out. To this end a flat rear end 42. might be formed to butt against abutment 41. In Figure 6 the abutment 43 conforms to the shape of seal end 32 which may then nest within the abutment. The abutments might be formed integrally during the pipe forming extrusion process. The presently proposed pipe joint is effective against both internal pressures as well as against infiltration pressures of ground water, tree roots, etc. The now proposed pipe joint is particularly effective in application to PVC pipes as are now commonly employed to provide a dramatically improved joint performance both in ease of layup and in sealing qualities in use. The use of the illustrated sealing ring enables reliable jointing. While the above has been given by way of illustrative example, many modifications and variations as would be apparent to persons skilled in the art may be made thereto without departing from the broad scope and ambit of the invention as herein set forth and claimed in the following claims.

Claims: CLAIMS 1. A pipe joint which comprises mating socket (20) and spigot (10) end pieces, the spigot end (10) being provided with a seal engaging outer surface, the socket end (20) of a pipe forming a-joint with said spigot end being provided with a spigot engaging portion (21) which receives the spigot end (11) therein to engage the spigot end (11) and align it with said socket, the socket end piece (20) being additionally formed with a seal engaging surface (22) which engages said seal to compress said seal between said surface (22) and the spigot end (10) such that a spigot end (10) carrying a seal thereon may be inserted into said socket to slide said seal along the inner seal engaging surface to a position whereat said spigot is sealably located within said spigot engaging portion of said socket. 2. A pipe joint as claimed in Claim 1, wherein said seal engaging outer surface of the spigot end (10) of a pipe is provided with a seal locating means (12) thereat. 3. A pipe joint as claimed in Claim 2, wherein said seal locating means (12) is a groove in the outer surface of the pipe adapted to receive therein a seal locating portion (30) of a seal, to retain the seal against movement along the pipe. 4. A pipe joint as claimed in Claim 2, wherein said seal locating means is an abutment (40) provided on the outer pipe surface to serve as a stop against movement of the seal by internal pressures. 5. A pipe joint as claimed in Claim 4, wherein said abutment (40) is a sleeve of material fitted over the spigot end (10) and adhered thereto. 6. A pipe joint as claimed in Claim 1, wherein a seal (33) is adhered immovably to the seal engaging outer surface of the spigot end (10) . - - 7. A pipe joint as claimed in Claim 1, wherein said seal comprises a sealing body portion (33) for compression between the sealing surfaces of the spigot (10) and socket pipe (20) ends having a forward ramp surface (31) angled downwardly and forwardly towards the end of the spigot (11) and tapered, outwardly flared, rearwardly projected fins (32, 34) to engage against respective spigot and socket sealing surfaces. 8. A pipe joint as claimed in Claim 7, wherein said seal engaging outer surface of the spigot end of a pipe is provided with a seal locating means (12, 40, 41, 43) thereat. 9. A pipe joint as claimed in Claim 8, wherein said seal locating means is a groove (12) in the outer surface of the pipe adapted to receive therein a seal locating portion (30) of a seal, to retain the seal against movement along the pipe. 10. A pipe joint as claimed in Claim 8, wherein said seal locating means is an abutment (40, 41, 43) provided on the outer pipe surface to serve as a stop against movement of the seal by internal pressures. 11. A pipe joint as claimed in Claim 10, wherein said abutment is a sleeve of material (40) fitted over the spigot end and adhered thereto. 12. A pipe joint as claimed in Claim 10, wherein said abutment (41, 43) is integrally formed with the material of the pipe. 13. A pipe joint as claimed in any one of the preceding claims wherein said socket end is comprised of two axially adjacent portions (21, 22) having internal diameters greater than the pipe diameter, the first outer end portion having the greatest diameter for compression of a seal between it and a spigot end, the second inner portion being of sufficient diameter to receive a spigot end (11) therein to align the spigot end within the socket. 14. A pipe joint as claimed in Claim 13, wherein said seal engaging outer surface of the spigot end of a pipe is provided with a seal locating means (12, 40, 41, 43) thereat. 15. A pipe joint as claimed in Claim 14, wherein said seal locating means is a groove (12) in the outer surface of the pipe adapted to receive therein a seal locating portion of a seal, to retain the seal against movement along the pipe. 16. A pipe joint as claimed in Claim 14, wherein said seal locating means is an abutment (40, 41, 43) provided on the outer pipe surface to serve as a stop against movement of the seal by internal pressures. 17. A pipe joint as claimed in Claim 16, wherein said abutment is a sleeve of material (40) fitted over the spigot end and adhered thereto. 18. A pipe joint as claimed in Claim 17, wherein said abutment (41, 43) is integrally formed with the material of the pipe. 19. A pipe joint as claimed in Claim 13, wherein said socket comprises an outwardly flared section (23) on the outer end of said first section to assist in guiding spigot ends thereinto. 20. A pipe joint as claimed in Claim 13, wherein said socket is moulded into the end of a length of PVC pipe.

Inventors: WILSON RALPH, WILSON, RALPH
Applicants: FINRING MFG, FINRING MANUFACTURING PTY. LTD.
Application year: 1984
Main classification: F16L47
IPC codes: F16L17