WO2009024787A1

WO2009024787A1 - Push-fit pipe fitting system

Info

Publication number: WO2009024787A1
Application number: PCT/GB2008/002828
Authority: WO
Inventors: Adrian Bristow; Geert Brookman; Steve Sutcliffe; Ray Fisher
Original assignee: Wavin B.V.
Priority date: 2007-08-20
Filing date: 2008-08-20
Publication date: 2009-02-26
Also published as: GB2452038B; GB0716222D0; GB2452038A

Abstract

A push-fit pipe fitting system comprises a fitting having a body portion (2) defining a bore (3) for receiving a pipe (6) and a sleeve (4) adapted to be received within an end portion of the pipe (6). The bore (3) is provided with gripping means (8) for retaining the pipe (6) within the bore (3) and a seal (10) for effecting a seal between the pipe (6) and the fitting. The bore (3) comprises a first location formation (14) and the sleeve comprises a second location formation (36). The first and second location formations (19, 36) are adapted to cooperate in a tactile and/or audible manner during insertion of the pipe (6) into the (bore 3) in order to indicate a predetermined position of the pipe (6) within the bore (3).

Description

PUSH-FIT PIPE FITTING SYSTEM

The present invention relates to a push-fit pipe fitting system and particularly, but not exclusively, to a system for use for example in plumbing applications for connecting water pipes. The invention also relates to components for use in such a system.

Push- fit pipe fitting systems typically comprise couplings and other components that are each provided with at least one tubular body portion for housing a sealing ring and a gripping means for resisting or preventing the withdrawal of a pipe once it has been pushed into the bore of the tubular body portion.

Both the sealing ring and the gripping means (typically a grab ring or wedge-like structure) are inherently required to co-operate very intimately with the pipe to form a joint. As a consequence of this, either or both of them tend to offer some resistance to the insertion of the pipe upon assembly of the joint. It is not uncommon for this resistance to be misinterpreted as the pipe reaching the end of the bore, thereby indicating that it is fully inserted. If this occurs, it is likely that the joint will not have been properly formed and, therefore, either or both of the sealing ring and the gripping means will be unable to perform their proper function, hi such a case, the joint can leak and, as the system is pressurized or some other load is applied to the joint, catastrophic failure can occur.

Various solutions have been proposed in order to address the above problem, hi many cases, these include observation apertures or some other visible means. Pipe fittings incorporating such structures can be complex and expensive to manufacture, hi addition, visible insertion indicators are ineffective in poor light or where the fitting is obstructed from view during connection to the pipe. The present invention sets out to overcome the above problems of the prior art. Accordingly, a first aspect of the invention provides a push-fit pipe fitting system comprising a fitting having a body portion defining a bore for receiving a pipe, the said bore being provided with gripping means for retaining the said pipe within the bore and a seal for effecting a seal between the said pipe and the said fitting; and a sleeve adapted to be received within an end portion of the said pipe; wherein the bore comprises a first location formation and the sleeve comprises a second location formation, the said first and second location formations being adapted to cooperate in a tactile and/or audible manner during insertion of the said pipe into the said bore in order to indicate a predetermined position of the said pipe within the said bore.

Such a system enables the person assembling a push-fit joint to hear and/or feel when the joint is properly formed. In addition, by providing the first location formation upon the sleeve, no special treatment of the pipe end is required, thereby avoiding the need for the assembler to carry out any additional operations.

Preferred features of this aspect of the invention are set out in Claims 2 to 31.

In embodiments where one of the location formations is formed upon an annular member, axial movement of the annular member will enable the co-operating location formations to move axially together under loading of the joint, thereby reducing the risk of separation.

In certain embodiments, such as where one of the location formations takes the form of a tongue and the other incorporates a groove, the engagement between the location formations is releasable, thereby enabling the joint to be re-usable.

A second aspect of the invention provides a push- fit pipe fitting as set out in Claim 32. Preferred features of this aspect of the invention are set out in Claims 33 to 49.

A third aspect of the invention provides a sleeve for use in a push- fit pipe fitting system as set out in claim 50. Preferred features of this aspect of the invention are set out in Claims 51 to 62. Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings in which:

Figure 1 is a section through a joint assembly in accordance with a first embodiment of the invention;

Figures 2a and 2b are perspective views of a bush forming part of the fitting from the joint assembly of Figure 1;

Figure 3 is a perspective view of the sleeve forming part of the joint assembly of Figure l;

Figures 4a-4k are side views of alternative sleeves in accordance with the invention;

Figures 5a-5c are sectional views showing the formation and loading of a joint using the joint assembly of Figure 1;

Figure 6 is a sectional view of a joint assembly in accordance with a second embodiment of the invention;

Figures 7a and 7b are perspective views of the bush from the fitting of the joint assembly of Figure 6;

Figures 8a and 8b are sectional views illustrating the formation of a joint using the joint assembly of Figure 6;

Figures 9 and 10 are, respectively, perspective views of a sleeve and a bush in accordance with a third embodiment of the invention; and

Figure 11 is a sectional view of a joint assembly forming a joint in accordance with a fourth embodiment of the invention. Figure 1 shows a joint assembly forming part of a push-fit pipe fitting system in accordance with a first embodiment of the invention. It will be seen that the illustrated joint assembly comprises a socket in the shape of a body portion 2 which comprises a bore 3 for receiving a sleeve 4 inserted within the end of a pipe 6. The body portion 2 can be formed from a wide variety of materials, including various plastics (such as polybutylene) and brass.

Figure 1 (along with all other figures of this specification) is somewhat schematic in that the body portion 2 is merely part of a fitting, the remainder of which is not shown. The remainder of the fitting can have an almost infinite variety of overall shapes and configurations, both in terms of its function and its appearance. For example, the fitting could be a simple coupling, for joining two lengths of pipe together; a more complex joint, such as an elbow; or something more complex, such as a T-junction, a manifold or a valve. Some of these fittings will include other socket-defining body portions and these need not necessarily have a similar structure to the illustrated body portion. The non-illustrated parts of the fitting will not be discussed further.

The body portion 2 comprises gripping means in the form of a grab ring 8, and a seal 10, both of which are annular and coaxially accommodated within the bore 3. The seal 10 is adapted to accommodate the pipe 6 and seal between its radially outer surface and a radially inner surface of the bore 3 when the pipe 6 is fully received within the bore 3. The grab ring 8 has inclined teeth 9 which are adapted to flex as the pipe is inserted into the bore, thereby permitting its insertion. The inclination of the teeth is, however, such as to resist removal of the pipe from the bore after insertion and, particularly, during axial loading of the type experienced when the system is pressurized. The specific shape and configuration of the grab ring and the seal are not relevant to the invention and a wide variety of alternative gripping means and seals could be used in their place. In view of this, the precise details of the grab ring 8 and the seal 10 will not be discussed further except where relevant to the operation of the invention.

The bore 3 is further provided with a bush 12, which takes the form of an annular member. The bush 12 is provided with three tongues 14, each of which is integrally formed with a main body portion 15 of the bush 12. As can be seen clearly from Figure 1, each of the tongues 14 has a cross-section that is generally "J"-shaped. That is to say each of the tongues has a radially inwardly and axially inwardly (in the sense of the bore 3) oriented portion which defines an insertion bearing surface 16. In addition, each of the tongues 14 also comprises a distal return portion 17, which defines a withdrawal bearing surface 18 that faces in a radially inward and axially inward direction.

The bush is manufactured from a polymer having resilient characteristics, but it could also be produced from metal

The tongues 14 are accommodated within correspondingly configured slots within a skirt 24. The skirt 24 has a diameter which is narrower than that of the main body 15 of the bush 12 in order to guide the insertion of the pipe and sleeve and provide lateral support once the joint is assembled. The skirt 24 also serves to protect the tongues laterally. The axially innermost end of the skirt 24 terminates in a radially inwardly extending flange which defines a pipe stop 22. The flange 22 is generally annular in configuration and, at its radially inner edge, is provided with a short axially-extending cylindrical neck 26. Neck 26 provides a smooth transition through the bore of the fitting when the joint is assembled, as can be seen in Figure 5b. Neck 26 also assists in the location of the bush 12 within the bore 3.

The bush 12 is further provided with a radially-outwardly extending seating flange 20. This flange sits on a correspondingly configured rebate 21 provided in the body portion, so as to limit its axially inward movement. Note, however, that the bush 12 is free to move in the opposite axial direction to a limited extent.

The provision of the bush 12 at the axially innermost portion of the bore 3 facilitates automated top-down assembly in which the body portion is oriented as shown in the figures. The other components are assembled over the top of the bush 12 which sits supported during the process.

The sleeve 4 comprises an insertion portion 28 that is retained within the pipe 16 by one or more anchor formations that will be discussed in more detail below. The remainder of the sleeve defines an extension portion 30 which includes a nose 32 at its axial end. The nose is provided with an annular camming surface 34 that faces in a radially outward and axially inward direction (relative to the bore 3). Midway along the length of the extension portion 30, there is provided an annular channel 36.

The remainder of the extension portion 30 is defined by a flange-like portion comprising a frusto conical surface 37 having an orientation broadly the same as the camming surface 34 and an axially-facing stop surface 39 for abutting against the end of the pipe 6 when the sleeve 4 is fitted to the pipe 6.

Figures 4a to 4k show a number of alternative examples of anchor formations 38a-38k. Each of these anchor formations has essentially the same purpose: to secure the position of the sleeve 4 within the end of the pipe 6. The anchor formations 38 can be employed in any of the embodiments of the invention specifically described in this specification, or any other embodiment. The various anchor formations all have the common feature of including some form of radial projection that, in some cases, serves to cause a corresponding radial deflection or deformation within the structure of the pipe. Due to the somewhat resilient physical characteristics of the pipe, this radial deformation causes it to exert an opposing radial force that essentially grips the sleeve and retains it in pace. In some cases the anchor formations themselves deflect and retention of the sleeve is, in this case, due to the resilient nature of this deflection causing a reaction against the pipe. A resisting force may be provided by a combination of both of these actions.

Figure 4a shows a sleeve 4 in which the anchor formations 38a take the form of a portion of the insertion portion 28 which is radially offset from the remainder. The offset portion has a somewhat arcuate profile.

Figure 4b shows a sleeve 4 in which the anchor formations 38b take the form of a series of teeth with profiles that are generally in the form of right-angled triangles. The teeth are orientated such that they deflect to allow the insertion of the sleeve 4 into the pipe 6, yet bite into the radially inner surface of the pipe 6 to resist withdrawal. Figure 4c shows a sleeve 4 in which the anchor formations 48 take the form of lugs 38c, each of which is accommodated within a respective aperture. The lugs are essentially hinged, so as to enable them to deflect into their respective apertures to facilitate insertion of the sleeve 4 into the pipe 6, yet move radially outwardly in order to lock the sleeve 4 within the pipe 6 upon the application of a withdrawing force.

Figure 4d has a radially offset portion at the distal end of the insertion portion 28. Although this radially offset portion 38d has a stepped profile, its principle of operation is broadly the same as that of Figure 4a.

Figure 4e comprises an anchor formation 38e in which an elastomeric ring is seated within an annular recess on the insertion portion 28. This ring is provided with an inclined surface that facilitates insertion of the sleeve 4 within the pipe 6. The compression of the elastomeric ring 38e between the sleeve 4 and the radially inner surface of the pipe 6 serves to resist withdrawal of the sleeve 4 from the pipe 6.

Figure 4f comprises an anchor portion 38 in the form of a section of the insertion portion 28 having an increased diameter. In the present case, this section 38f happens to be provided at a distal end of the insertion portion, but it could be provided at other positions along its length.

Figure 4g illustrates a sleeve 4 provided with a plurality of axially-aligned ribs 38g set at equidistant, spaced positions around the circumference of the insertion portion 28. As with other versions of the anchor formation, the ribs are provided with chamfers in order to aid the insertion of the sleeve 4 within the pipe 6.

Figure 4h shows a version of the sleeve 4 in which teeth 38b similar to those of Figure 4b are provided in conjunction with a pair of annular, coaxial ribs 38i. These ribs have inclined surfaces for facilitating insertion of the sleeve 4 within the pipe 6.

Figure 4i comprises five annular ribs 38a having a substantially identical shape to those ofFigure 4h. Figure 4j comprises a pair of diametrically opposed inclined teeth, each accommodated within a respective recess.

Figure 4k comprises an anchor formation 38k in the form of a pair of opposed tongues accommodated within respective apertures. The tongues compress into the apertures upon insertion of the sleeve 4 into the pipe 6, yet are urged resiliency radially outwardly, so as to resist withdrawal of the sleeve.

An additional example of an anchor formation in accordance with the invention comprises a helical flange, effectively defining a screw-thread. Such a formation can enable the sleeve 4 to be screwed into the pipe.

Operation of the assembly will now be described with reference to Figures 5a to 5c.

In Figure 5 a, sleeve 4 has been inserted into the pipe 6 and the combined sleeve 4 and pipe 6 have been inserted into the body portion 2 of the fitting, to the extent that they have entered into the bore with the extension portion 30 of the sleeve located axially inwardly of the grab ring 8 and the seal 10. At this point, the nose 32 of the sleeve 4 begins to bear against the insertion bearing surfaces 16 of the tongues 14. As the pipe 6 is urged further into the bore 3, the nose 32 cams against the insertion bearing surfaces 16 and urges them radially outwardly, so as to deflect the tongues about their junctions with the main body portion 15 of the bush 12.

Once the nose 32 progresses beyond the axially inner ends of the insertion bearing surfaces 16, the resilience of the tongues 14 causes them to return radially inwardly with something of a "snapping" action as the nose meets the pipe stop 22 of the bush. The person inserting the pipe into the fitting therefore feels a gradual rise in the resistance to insertion as the nose 32 cams over the insertion bearing surfaces 16, followed by a sudden drop in the resistance and then an abrupt stop as the pipe reaches its final resting place. This rather satisfying "click" into place provides both an audible and physical indication of the correct establishment of the joint between the pipe and the^ fitting. From the above, it will be appreciated that the tongues essentially define a first location formation and the channel a second. The two formations co-operate to indicate the location of the pipe/sleeve relative to the fitting.

The degree of resistance offered by the first location formation can be carefully controlled by the thickness/orientation of the tongues and appropriate selection of material.

It should here be noted that the pipe stop 22 could be omitted from the bush 12 and provided, instead, as a feature of the body portion itself. However, as the body portions of different fittings will in practice be made from a variety of materials, it has been found that providing the pipe stop 22 on the bush 12 has the added benefit of providing a consistency of feel, thereby enhancing the audible and tactile nature of the indication.

Figure 5c shows the joint effected by the jointing assembly under axial load. Here it will be seen that the back of the nose 32 of the sleeve 4 bears against the withdrawal bearing surface 18. This causes a withdrawing force to be exerted on the bush 12. The configuration of the bush 12 is such that it is able to slide axially within the bore 3 - the flange 20 is so configured as to prevent only axially inward movement and allow a certain amount of axially outward movement of the bush 12. In addition, the grab ring 8 initially also has freedom to move axially within the bore 4, as does the seal. However, the purpose of the grab ring is to resist withdrawal of the pipe from the body portion 2 and it can be seen in the figure that it is doing this by eventually biting into the radially outer surface of the grab ring because the limit of axial movement has been reached.

In the present embodiment, a release tool 19 is provided for releasing the engagement of the teeth of the grab wedge 8 from the radially outer surface of the pipe 6. Once the tool is brought into operation in this manner, the pipe can be withdrawn from the body portion 2. As this happens, the anchor formations 38 continue to lock the sleeve 4 within the pipe 6, so that it is correspondingly withdrawn from the body portion 2. At this stage, the rear of the nose 32 of the sleeve 4 acts upon the withdrawal bearing surfaces 18 of the tongues 14 and thereby forces them radially outwardly. This operation is assisted by flange 20 bearing against the seal 10 and the other internal components.

Once the nose 32 of the sleeve 4 moves beyond the junctions between the insertion bearing surfaces 16 and the withdrawal bearing surfaces 18, the tongues 14 snap back into place and the withdrawal of the pipe 6 can continue further without resistance. It will be noted that, following this operation, the bush 12 has returned to its pre-joint condition and the fitting is therefore ready to be re-used.

Although the invention is intended to work as described above, the configuration of the socket is such that it will still operate with a plain pipe end, if a sleeve is not available, hi such a case, a joint can still be formed, but there will be no indication regarding the extent of insertion of the pipe or the correctness of the joint. However, where the gripping mechanism is releasable, such a joint could be treated as a temporary measure, if so preferred.

A second embodiment of the invention will now be described with reference to Figures 6 to 8b. As will be seen from Figure 6, this embodiment has broad similarity to the embodiment of Figure 1, the primary difference subsisting in the shape and configuration of the bush 12. In this case, the tongues and skirt are replaced by an alternative location formation in the form of a deformable wall 41 provided with a pair of radially inwardly directed circumferential ribs 43. In this case, the ribs 43 are arranged as a pair and are situated in a diametrically opposed manner at the axially inward end of the deformable wall 41.

The deformable wall 41 has a wall thickness that is somewhat thinner than that of the main body 15 of the bush 12. This is to enable the wall to deform in order to accommodate an increase in lateral separation of the two ribs 43. Each of the ribs 43 has a somewhat rhomboid shape in cross-section, being provided with an insertion bearing surface 45 that faces radially inwardly and axially outwardly. The other side of each of the ribs 43, defines a withdrawal bearing surface 47 that faces axially inwardly and radially inwardly. The sleeve need not differ from the first embodiment in order to cooperate with the fitting of this embodiment.

The operation of this embodiment of the invention will be described further with reference to Figures 8a and 8b.

As can be seen in Figure 8a, as the combined pipe 6 and sleeve 4 are inserted into the bore 3 of the body portion 2, the nose 32 of the sleeve 4 initially bears against the insertion bearing surface 45. hi a similar manner to the previous embodiment, further insertion of the pipe causes the camming surface 34 of the nose to bear against the ribs 43 and urge them radially outwardly. In this case, the radially outward movement is rendered possible by the deformation of the deformable wall 41, which is urged into an oval configuration, so as to let the nose 32 pass. As the nose 32 proceeds past the ribs 43, the resilience of the deformable wall 41 causes the ribs 43 to snap back to their original position, whereupon they engage the channel 36 provided in the extension portion 30 of the sleeve 4. At this stage, the insertion bearing surfaces abut the axially outermost side surface of the channel 36, which acts as a pipe stop 40. It will be noted that, in this case, there is no additional pipe stop provided on either the wall of the bore or indeed on the bush 12 itself.

The pipe and sleeve can be withdrawn together in a re-usable manner, as with the previous embodiment.

Although the above embodiments show laterally movable location formations in the body portion and non-deformable location formations on the extension portion of the sleeve, this configuration could be reversed. Figures 9 and 10 show, respectively, a sleeve 4 and a bush 12, which embody such a reverse configuration.

In this case it can be seen that the displacement to effect the snap- fit between the sleeve and the bush is provided by dividing the extension portion of the pipe 6 into a series of tongues 50. Conversely, the bush 12 is provided with an entire annular projection 52 which co-operates with and engages within the channel 36 provided in the sleeve. In the above embodiments, the "male" aspect of the insertion indicator is provided on the sleeve and the "female" aspect of the insertion indicator is provided in the body portion. However, it is equally possible for this to be reversed and Figure 11 shows an embodiment in which this is the case. Although in this embodiment the bush is provided with a rigid portion and the sleeve is provided with flexible tongues, this could also be reversed.

In each of the above embodiments, the location formation situated within the body portion is provided on a bush. However, it is equally possible for such formations to be moulded into the body portion as an integral part of that component.

Many further modifications and variations will suggest themselves to those skilled in the art upon making reference to the above embodiments which are not intended to limit the scope of the invention, that being determined by the appended claims.

Claims

CLAIMS:

1. A push-fit pipe fitting system comprising: a fitting having a body portion defining a bore for receiving a pipe, the said bore being provided with gripping means for retaining the said pipe within the bore and a seal for effecting a seal between the said pipe and the said fitting; and a sleeve adapted to be received within an end portion of the said pipe; wherein the bore comprises a first location formation and the sleeve comprises a second location formation, the said first and second location formations being adapted to cooperate in a tactile and/or audible manner during insertion of the said pipe into the said bore in order to indicate a predetermined position of the said pipe within the said bore.

2. A push- fit pipe fitting system according to Claim 1, wherein the said first location formation includes at least one engagement tongue adapted to co-operate with the said second location formation.

3. A push- fit pipe fitting system according to Claim 2, wherein the said first location formation includes a plurality of said engagement tongues.

4. A push-fit pipe fitting system according to Claim 2 or 3, wherein the or each said engagement tongue extends generally axially inwardly and radially inwardly when in an unstressed condition.

5. A push- fit pipe fitting system according to Claim 2, 3 or 4, wherein the or each said engagement tongue is provided with a bearing surface for facilitating removal of the said pipe from the said bore.

6. A push-fit pipe fitting system according to Claim 5, wherein the or each said bearing surface is defined by an axially inwardly and radially inwardly directed surface provided on a respective said engagement tongue.

7. A push- fit pipe fitting system according to Claim 6, wherein the or each said bearing surface is defined by an axially inwardly and radially outwardly extending distal return portion of the respective said engagement tongue.

8. A push-fit pipe fitting system according to one of Claims 2 to 7 and comprising three said engagement tongues arranged at 120° intervals about the circumference of the said bore.

9. A push- fit pipe fitting system according to Claim 1, wherein the said first location formation includes an annular, deformable wall section arranged to be co-axial with the said bore and provided with a radially inwardly directed projection at an axially inner axial end region thereof.

10. A push- fit pipe fitting system according to Claim 9, comprising a plurality of said radially inwardly directed projections disposed at circumferentially spaced locations about the said deformable wall section.

11. A push- fit pipe fitting system according to Claim 1, wherein the said first location formation includes an annular, radially inwardly directed projection arranged coaxially within the said bore.

12. A push- fit pipe fitting system according to any preceding claim, wherein the said first location formation is provided on an annular member located coaxially with the said bore.

13. A push- fit pipe fitting system according to Claim 12, wherein the said annular member comprises a radially outwardly extending flange in an axially outer region thereof, the said flange being adapted to aid orientation of the said annular member within the said bore.

14. A push-fit piece fitting system according to one of Claims 12 or 13, wherein the said annular member comprises an axially inner portion having a reduced diameter for aligning the said pipe and/or sleeve during insertion of the said pipe into the said bore.

15. A push- fit pipe fitting according to one of Claims 12 to 14, wherein the said annular member is adapted to slide axially within the said bore in the event that the pipe moves axially relative to the said coupling under load.

16. A push-fit pipe fitting according to one of Claims 12 to 15, wherein the said annular member further comprises a radially inwardly directed stop-formation adapted to cause termination of the insertion of the pipe into the said bore.

17. A push- fit pipe fitting system according to one of Claims 12 to 16 when dependent directly or indirectly upon Claim 2, wherein the or each said tongue is received generally within a protective skirt formed by a portion of the said annular ring.

18. A push- fit pipe fitting system according to one of claims 1 to 11 , wherein the said first location formation is formed integrally with the said body portion.

19. A push-fit pipe fitting system according to any preceding claim, wherein the said sleeve comprises an insertion portion for location within the end portion of the said pipe when installed for use, and an extension portion that is adapted to project axially from the end portion of the pipe, the said second location formation being formed upon the extension portion.

20. A push-fit pipe fitting system according to Claim 19, wherein the said second location formation comprises an annular channel formed in a radially outer surface of the said extension portion.

21. A push- fit pipe fitting system according to Claim 19 or 20, wherein a distal portion of the said extension portion is divided into a plurality of circumferentially spaced sections, such that the extension portion is able to contract in diameter as it contacts the said first engagement portion.

22. A push-fit pipe fitting system according to Claim 19, 20 or 21 wherein the said sleeve is provided with an anchor formation for retaining the said insertion portion of the sleeve within the said end portion of the pipe during use.

23. A push- fit pipe fitting system according to Claim 22, wherein the said anchor formation comprises one or more radially outwardly projecting tongues.

24. A push- fit pipe fitting system according to Claim 22 or 23, wherein the said anchor formation comprises one or more radially outwardly projecting teeth.

25. A push- fit pipe fitting system according to Claim 22, 23 or 24, wherein the said anchor formation comprises one or more radially outwardly projecting ribs.

26. A push- fit pipe fitting system according to Claim 25, wherein at least one of the said ribs is elongate and aligned parallel to the longitudinal axis of the said sleeve.

27. A push-fit pipe fitting system according to Claim 25 or 26, wherein at least one of the said ribs is annular and arranged circumferentially about the said insertion portion.

28. A push- fit pipe fitting system according to one of Claims 22 to 27, wherein the said anchor portion comprises a radially offset section of the said insertion portion.

29. A push- fit pipe fitting system according to one of Claims 22 to 28, wherein the said anchor portion comprises a compressible member.

30. A push-fit pipe fitting system according to Claim 29, wherein the said compressible member is an annular ring located coaxially about the perimeter of the said insertion portion.

31. A push- fit pipe fitting system according to one of Claims 22 to 30, wherein the said anchor portion comprises an annular region having a diameter greater than the basic diameter of the said insertion portion.

32. A push- fit pipe fitting having a body portion defining a bore for receiving a pipe, the said bore being provided with gripping means for retaining the said pipe within the bore and a seal for effecting a seal between the said pipe and the said fitting; wherein the bore comprises a first location formation adapted to cooperate with a sleeve fitted to an end portion of the said pipe in a tactile and/or audible manner during insertion of the said pipe into the said bore in order to indicate a predetermined position of the said pipe within the said bore.

33. A fitting according to Claim 32, wherein the said location formation includes at least one engagement tongue.

34. A fitting according to Claim 33, wherein the said location formation includes a plurality of said engagement tongues.

35. A fitting according to Claim 33 or 34, wherein the or each said engagement tongue extends generally axially inwardly and radially inwardly when in an unstressed condition.

36. A fitting according to Claim 33, 34 or 35, wherein the or each said engagement tongue is provided with a bearing surface for facilitating removal of the said pipe from the said bore.

37. A fitting according to Claim 36, wherein the or each said bearing surface is defined by an axially inwardly and radially inwardly directed surface provided on a respective said engagement tongue.

38. A fitting according to Claim 37, wherein the or each said bearing surface is defined by an axially inwardly and radially outwardly extending distal return portion of the respective said engagement tongue.

39. A fitting according to one of Claims 33 to 38 and comprising three said engagement tongues arranged at 120° intervals about the circumference of the said bore.

40. A fitting according to Claim 32, wherein the said location formation includes an annular, deformable wall section arranged to be co-axial with the said bore and provided with a radially inwardly directed projection at an axially inner axial end region thereof.

41. A fitting according to Claim 40, comprising a plurality of said radially inwardly directed projections disposed at circumferentially spaced locations about the said deformable wall section.

42. A fitting according to Claim 32, wherein the said location formation includes an annular, radially inwardly directed projection arranged coaxially within the said bore.

43. A fitting according to any one of Claims 32 to 42, wherein the said location formation is provided on an annular member located coaxially with the said bore.

44. A fitting according to Claim 43, wherein the said annular member comprises a radially outwardly extending flange in an axially outer region thereof, the said flange being adapted to aid orientation of the said annular member within the said bore.

45. A fitting according to one of Claims 43 or 44, wherein the said annular member comprises an axially inner portion having a reduced diameter for aligning the said pipe and/or sleeve during insertion of the said pipe into the said bore.

46. A fitting according to one of Claims 43 to 45, wherein the said annular member is adapted to slide axially within the said bore in the event that the pipe moves axially relative to the said coupling under load.

47. A fitting according to one of Claims 43 to 46, wherein the said annular member further comprises a radially inwardly directed stop-formation adapted to cause termination of the insertion of the pipe into the said bore.

48. A fitting according to one of Claims 43 to 47 when dependent directly or indirectly upon Claim 33, wherein the or each said tongue is received generally within a protective skirt formed by a portion of the said annular ring.

49. A fitting according to one of claims 32 to 42, wherein the said location formation is formed integrally with the said body portion.

50. A sleeve for use in a push-fit pipe fitting system, the said sleeve comprising an insertion portion for location within the end portion of a pipe when installed for use, and an extension portion that is adapted to project axially from the end portion of the pipe; wherein the extension comprises a location formation adapted to cooperate with a fitting in a tactile and/or audible manner during insertion of the said pipe into a bore of the said fitting in order to indicate a predetermined position of the said pipe within the said bore.

51. A sleeve according to Claim 50, wherein the said location formation comprises an annular channel formed in a radially outer surface of the said extension portion.

52. A sleeve according to Claim 50 or 51, wherein a distal portion of the said extension portion is divided into a plurality of circumferentially spaced sections, such that the extension portion is able to contract in diameter as it contacts the said first engagement portion.

53. A sleeve according to Claim 50, 51 or 52, wherein the said sleeve is provided with an anchor formation for retaining the said insertion portion of the sleeve within the said end portion of the pipe during use.

54. A sleeve according to Claim 53, wherein the said anchor formation comprises one or more radially outwardly projecting tongues.

55. A sleeve according to Claim 53 or 54, wherein the said anchor formation comprises one or more radially outwardly projecting teeth.

56. A sleeve according to Claim 53, 54 or 55, wherein the said anchor formation comprises one or more radially outwardly projecting ribs.

57. A sleeve according to Claim 56, wherein at least one of the said ribs is elongate and aligned parallel to the longitudinal axis of the said sleeve.

58. A sleeve according to Claim 56 or 57, wherein at least one of the said ribs is annular and arranged circumferentially about the said insertion portion.

59. A sleeve according to one of Claims 53 to 58, wherein the said anchor portion comprises a radially offset section of the said insertion portion.

60. A sleeve according to one of Claims 53 to 59, wherein the said anchor portion comprises a compressible member.

61. A sleeve according to Claim 60, wherein the said compressible member is an annular ring located coaxially about the perimeter of the said insertion portion.

62. A sleeve according to one of Claims 53 to 61, wherein the said anchor portion comprises an annular region having a diameter greater than the basic diameter of the said insertion portion.

63. A push- fit pipe fitting system substantially as hereinbefore described with reference to the accompanying drawings.

64. A push-fit pipe fitting substantially as hereinbefore described with reference to the accompanying drawings.

65. A sleeve for use in a push- fit pipe fitting system substantially as hereinbefore described with reference to the accompanying drawings.