AU2006203094B2

AU2006203094B2 - End Fitting for Pipe

Info

Publication number: AU2006203094B2
Application number: AU2006203094A
Authority: AU
Inventors: Peter Glanville Chapman; James Henwood; George Macovaz
Original assignee: Vinidex Pty Ltd
Current assignee: Vinidex Pty Ltd
Priority date: 2005-07-19
Filing date: 2006-07-19
Publication date: 2012-05-31
Anticipated expiration: 2026-07-19
Also published as: AU2006203094A1

Abstract

A pipe end fitting (12) for protecting the end of a pipe (10) for jointing with a socket (26) and sealing ring (32) arrangement includes an attachment portion (14) adapted for attaching the fitting to the pipe end, and a generally annular end portion (16) extending past and generally coaxial with the pipe end, the end portion having a tapered outside surface at its end to serve as a lead-in portion for pushing the pipe end past the sealing ring. The attachment portion of the end fitting may have deformable formations (115) which allow fitting to range of pipe internal diameters. Fig. 2 C*4A -4--

Description

TITLE OF THE INVENTION END FITTING FOR PIPE BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an end fitting for a pipe, and particularly to a fitting for the spigot formed at the end of the pipe. The invention is particularly, though not exclusively, adapted for use in conjunction with thin-walled plastics or metal pipes - e.g. of diameter to wall thicknesses ratios greater than about 30 for polyvinyl chloride (PVC), about 20 for polyethylene (PE) and about 40 for steel - and is described here in that context, but has more general application to pipes of any thickness. 2. Description of Related Art [00021 Pipes are often formed to allow jointing with similar pipes by means of a push-fit connection, by creating a bell (or socket) of increased diameter at one end of the pipe, formed to retain a rubber sealing ring. Methods for forming the bell on a plastics pipe are well understood in the art. 100031 The other end, or spigot, of the pipe is of the same internal and external diameters as the pipe body, and is adapted to be pushed into the bell of the adjacent pipe so that the sealing ring seals against the outside surface of the spigot. The end of the spigot is often chamfered at its outside surface to provide a lead-in for pushing past the rubber ring. 100041 Improvements in pipe production have allowed pipes to be produced with thin wall thicknesses, but which nevertheless provide adequate circumferential and diametral strength to withstand the internal pressure and external loads on the pipe in use.

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100051 Difficulties may arise at the spigot ends of such thin-walled pipes, where the chamfer on the spigot end may be inadequate, due to the thin wall, to facilitate entry to the socket past the sealing device during jointing, and may reduce the capacity of the spigot end to withstand forces encountered during jointing to other pipes or to other fittings, such as compression forces from sealing rings, or loads encountered in operation such as pressure thrusts such as those which may be exerted by valves or reducers. SUMMARY OF THE INVENTION 100061 The present invention seeks to overcome some or all of the above disadvantages. [00071 In one form, the invention provides a pipe end fitting including: an attachment portion adapted for attaching the fitting to a pipe end, and a generally annular end portion extending past and generally coaxial with the pipe end, said end portion having a tapered outside surface at its end. [00081 Preferably, said end portion has a maximum outside diameter substantially equal to the outside diameter of said pipe end, and includes an abutment surface for bearing against an end surface of the pipe. [00091 Preferably, said end portion has a maximum wall thickness greater than the wall thickness of the pipe end. 100101 A further form of the invention provides a connection arrangement for a pipe and socket, comprising: a pipe having an end spigot; a socket having a sealing ring, adapted for receiving the pipe spigot; 2 an end fitting of the type described above fitted to said end spigot and forming a lead-in portion for push-fit connection of the end spigot into the socket. [00111 A further form of the invention provides a method of forming a connection between a pipe end spigot and a socket having a sealing ring, including fitting an end fitting of the type described above to the pipe spigot and pushing the pipe spigot with the end fitting into the socket so that the end fitting forms a lead-in portion for the pipe spigot. [00121 The invention also provides a pipe and end fitting arrangement comprising an end fitting of the type described fitted to a pipe end, and a method of protecting a pipe end comprising fitting of an end fitting of the type described to a pipe end. 100131 Further aspects of the invention are set out in the claims. BRIEF DESCRIPTION OF THE DRAWINGS 100141 Further preferred embodiments of the invention will now be described with reference to the accompanying drawings, in which: 100151 Fig. I is an exploded view of a pipe end fitting according to an embodiment of the invention, fitted to a pipe end; 100161 Fig.2 is a schematic cross section of a pipe end, end fitting and pipe bell arrangement according to a further embodiment; and 100171 Figs. 3A and 3B are schematic side and partial cross section views of a pipe end fitting according to a further embodiment. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 10018] Fig. 1 is an exploded view of a plastics pipe end 10 and pipe end fitting 12 arrangement according to an embodiment of the invention. 3 100191 The pipe end 10 is square cut at its end, having inside and outside diameters substantially equal to those of the body of the pipe. The other end of the pipe (not shown) will typically include a pipe bell of increased diameter, as described and shown in Fig.2. 100201 The pipe end fitting 12 has a tubular attachment portion 14 having an outside diameter adapted for insertion in the pipe end to form an interference fit, preferably a tapered interference fit, against the inside surface of the pipe end to secure the fitting to the pipe end. [00211 The pipe fitting further comprises an end portion 16 which extends past the pipe end, including a land portion 18 and a tapered portion 20. The land 18 has an outside diameter substantially equal to that of the pipe end, so that when the fitting is attached to the pipe fitting the land 18 forms a continuation of the pipe outside surface. The length of the land is preferably kept as short as possible consistent with the required strength, for reasons discussed below with reference to Fig. 2, and in situations where there is minimal axial thrust to applied to the pipe spigot - such as where the pipe spigot is to be jointed to a thrust-supported fitting - the parallel land portion 18 of the end fitting may be shortened to just a few millimetres or may be omitted entirely. [00221 An axial, cylindrical bore 22 passes through the fitting, communicating with the bore 24 of the pipe. The fitting bore 22 is of smaller diameter than the bore 24 of the pipe. 100231 The fitting 12 may be made of metal, or of plastics, which may be reinforced by glass or other fillers or fibres. The fitting may be formed by any suitable method, such as by moulding or machining. 100241 Fig. 2 is a cross-section of a pipe end and fitting arrangement, further showing the use of the fitting in a bell connection jointing of the pipe to the bell 26 of an adjacent, similar pipe. The bell connection consists of an enlarged diameter bell 28 with a ring groove 30 which retains a rubber sealing ring 32. 4 [0025] It can be seen that the fitting is inserted into the pipe end such that a rear abutment surface 34 of the end portion 16 bears against the squared-off end surface 36 of the pipe end. [00261 In use, the tapered portion 20 of the fitting serves as a lead-in to allow the fitting to be pushed past the sealing ring 32, in a similar manner to the tapering of the pipe end in the prior art. [00271 As will be observed from Fig. 2, the length of end portion 16 of the fitting is less than the length from the back of the socket to the sealing ring 32, so that the end portion of the fitting passes completely beyond the sealing ring 32 and the ring seals against the outer surface of the pipe end. In this way the seal is between the two pipes, and it is not necessary to provide a separate seal between the fitting 12 and the pipe end 10. However, if necessary, a seal between the attachment portion 14 of the fitting and the pipe end may be formed, for example by providing a sealing ring (not shown) on the attachment portion. [00281 Keeping the length of the land portion 18 as short as possible also maximises the 'pull-out' length available, i.e. the length of pipe inserted past the seal. 100291 It will be further noted that the wall thickness at the end surface of the fitting tapered portion is at least approximately equal to, or greater than, the wall thickness at the pipe end, i.e. without chamfering. While the internal diameter of the bore of the fitting is reduced compared to that of the pipe body, it is considered that this will cause negligible difference in hydraulic performance in most applications. [00301 The end fitting thus provides a greater end wall thickness than would be the case of the pipe end being chamfered according to the prior art, providing protection to the pipe end during jointing and improved resistance to damage due to thrusts and compressive forces on joint in use. In the case that the end fitting is damaged during use, it can be replaced rather than requiring replacement of the pipe length. 5 [00311 While Fig. 2 illustrates a pipe-to-pipe connection, it will be appreciated that the invention has substantial application in connection of pipes to the sockets of other fittings, such as reducers or the cast iron sockets of valves in water supply installations. [0032] A further advantage of the invention is improved ease of installation in circumstances where the pipe is to be cut to length on site, whereby it can simply be cut off square without the need for chamfering. [00331 Fig. 3A is a side view of a further embodiment of the pipe end fitting which is adapted to accommodate variation in the internal diameter of the pipes to which it may be fitted, for example pipes of large tolerance in internal diameter or with the same outside diameter but different thickness (class) resulting in variations in internal diameter of up to 1.5-3%. In practice, it is likely that the fitting will allow for differences in wall thicknesses equivalent to one or perhaps two classes - each class having a 25% difference in wall thickness as a proportion of external diameter, e.g 1:32, 1:40, 1:50. [00341 Fig. 3B is a partial cross section view along line 3B-3B. [0035] The end fitting 112 is generally similar to the ones described with reference to Figs. 1 and 2 - having an attachment portion 114 and an end portion 116 having a land 118 and tapered end 120. [00361 The attachment portion 114 differ from that of Figs. I and 2 by being of reduced outside diameter and having a series of thin longitudinal or circumferential ribs 115 or other formations on its outside surface which are capable of deforming to form a resilient fit with pipes of a range of internal diameters. The ribs or other formation may be integrally formed, e.g. moulded, with the attachment portion, or may be separately formed such as a sleeve of elastomeric material such as rubber. [00371 In an alternative, unillustrated modification the attachment portion of the end fitting may be slotted or have other weakening formations to allow the 6 attachment portion to reduce in diameter to allow fitting to pipe spigots of smaller internal diameter. [00381 In this specification, the word "comprising" is to be understood in its "open" sense, that is, in the sense of "including", and thus not limited to its "closed" sense, that is the sense of "consisting only of'. A corresponding meaning is to be attributed to the corresponding words "comprise, comprised and comprises where they appear. 100391 While particular embodiments of this invention have been described, it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. The present embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. It will further be understood that any reference herein to known prior art does not, unless the contrary indication appears, constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates. 7

Claims

1. A pipe end fitting, for jointing a pipe end to a socket, including: an attachment portion adapted for attaching the fitting to the pipe end, and a generally annular end portion extending past and generally coaxial with the pipe end, said end portion having a tapered outside surface at its end.

2. A pipe end fitting according to claim 1, wherein the end portion has a maximum outside diameter substantially equal to the outside diameter of the pipe end, and includes an abutment surface for bearing against an end surface of the pipe.

3. A pipe end fitting according to claim 1 or 2, wherein said end portion has a maximum wall thickness greater than the wall thickness of the pipe end.

4. A pipe end fitting according to claim 1, wherein the end portion is adapted to provide a lead-in portion for fitting of the pipe end to the socket having a sealing ring.

5. A pipe end fitting according to claim 1, wherein the end portion is adapted to travel past the sealing ring so that the sealing ring forms a seal against the pipe.

6. A pipe end fitting according to claim 1, wherein the attachment portion is tubular and is adapted to fit inside the pipe end.

7. A pipe end fitting according to claim 6, wherein the attachment portion has a tapered outside surface adapted to form an interference fit with the inside surface of the pipe end.

8. A pipe end fitting according to claim 6, wherein the attachment portion has one or more formations adapted to provide a fit with a range of pipe ends of different internal diameters.

9. A pipe end fitting according to claim 8, wherein the formations are deformable formations located on an outer surface of the attachment portion. 8

10. A pipe end fitting according to claim 9, wherein the formations are deformable ribs.

11. A pipe end fitting according to claim 9, wherein the deformable formations comprise an elastomeric member on the outside of the attachment portion.

12. A pipe end fitting according to claim 8, wherein the formations comprise weakening formations which allow the attachment portion to reduce in diameter to fit smaller pipe end internal diameters.

13. A connection arrangement for a pipe and socket, comprising: a pipe having an end spigot; a socket having a sealing ring, adapted for receiving the pipe spigot; a pipe end fitting according to any one of claims I to 12 fitted to said end spigot and forming a lead-in portion for push-fit connection of the end spigot into the socket.

14. A connection arrangement for a pipe and socket according to claim 13, wherein said pipe end fitting is adapted to travel past the sealing ring so that the sealing ring forms a seal against the pipe.

15. A method of forming a connection between a pipe end spigot and a socket having a sealing ring, including fitting a pipe end fitting according to any one of claims I to 12 to the pipe spigot and pushing the pipe spigot with the pipe end fitting into the socket so that the pipe end fitting forms a lead-in portion for the pipe spigot.

16. A method according to claim 15, including the step of pushing the pipe end into the socket by a sufficient distance that the pipe end fitting travels past the sealing ring and the sealing ring seals against the outer surface of the pipe.

17. A method according to claim 15 or 16, wherein the socket is the bell of another pipe. 9

18. A method according to claim 15 of 16, wherein the socket is formed on a pipe fitting.

19. A method according to claim 18 wherein the pipe fitting having the socket is a valve.

20. A method according to claim 18 wherein the pipe fitting having the socket is a reducer.

21. A method according to any one of claims 15 to 20, including the step of cutting the pipe to length at the installation site prior to fitting the pipe end fitting.

22. A method according to any one of claims 15 to 21, wherein the pipe end fitting provides protection to the pipe end during jointing.

23. A method according to any one of claims 15 to 22, wherein the pipe end fitting provides resistance to thrust damage and compressive forces for the connection.

24. A pipe end fitting substantially as herein described with reference to any of Figs. 1, 2 or 3A and 3B.

25. A connection arrangement for a pipe, or a method of forming a pipe connection, substantially as herein described with reference to Fig. 2. 10