The present invention relates to joints in pipe installations, and more specifically to joints which can accommodate expansion and/or contraction.
Background
Known arrangements for accommodating pipe expansion typically employ a dedicated expansion joint which has pipe sections affixed either side, e.g. by means of flange couplings, wherein rubber seals are used to ensure a fluid-tight connection to the pipes either side of the expansion joint. However, the rubber seals of such prior art arrangements are prone to degrade with time which may compromise the integrity of the joints between the pipe and the expansion joint.
Accordingly, the present inventors have appreciated that an improved pipe joint which can accommodate expansion and contraction whilst not requiring the use of rubber seals would be desirable.
Summary of the Invention
According to a first aspect of the invention there is provided a pipe joint having an inlet and an outlet, the pipe joint comprising: an elongate sleeve having a flexible portion for accommodating expansion and/or contraction between said inlet and outlet, and an axially adjacent rigid portion providing one of said inlet or outlet; and a mating portion providing the other of said inlet or outlet, the mating portion having means for attaching to the flexible portion of the sleeve.
The expansion and contraction may be substantially along an axis extending from the inlet to the outlet.
An axis of the sleeve and an axis of the mating portion may be substantially parallel. The sleeve and the mating portion may be substantially coaxial.

The mating portion may have a radially outward shoulder for attaching the mating portion to the flexible portion of the sleeve, and the radially outward shoulder may be arranged to be electrofusion welded, solvent welded or butt welded to the flexible portion of the sleeve.
The mating portion may be substantially tubular. The sleeve may be substantially radially symmetrical.
The radially outward shoulder may be located at an intermediate axial position on the mating portion such that the mating portion extends partially into the sleeve when the mating portion is attached to the sleeve by means of the radially outward shoulder. The end of the mating portion above the radially outward shoulder may define the inlet or outlet.
The flexible portion of the sleeve may comprise one or more radially outward extending circumferential ribs, the ribs being configured to accommodate the expansion and/or contraction. The one or more circumferential ribs may surround the part of the mating portion below the radially outward shoulder which extends into the sleeve.
In one series of embodiments the sleeve may comprise one or more radially outwardly extending helical rib(s). Embodiments with a helical rib have greater flexibility than comparable embodiments with multiple concentric ribs.
The helical rib or ribs may be configured to accommodate the expansion and/or contraction. The helical rib or ribs may extend coaxially along the sleeve. The helical rib or ribs may surround the part of the mating portion below the radially outward shoulder which extends into the sleeve. In embodiments comprising two or more helical ribs, the ribs may be congruent with the same axis, for example, the ribs may define a double or triple (or greater) helix.
The pitch and/or helix angle of the one or more helical ribs may be configured to provide at least three, at least four, at least five, or at least six complete helical turns. By adjusting the pitch and/or helix angle and/or the number of turns it is possible to adjust the flexibility of the flexible portion. The pitch and/or helix angle may be constant along the length of the at least one helical rib.

In an alternative series of embodiments, the pitch and/or helix angle may vary along the length of the at least one helical rib. For example, the at least one helical rib may comprise a first portion with a first pitch and/or helix angle, and at least one second portion with a second pitch and/or helix angle, different to the first. The helical rib may comprise more than one first and/or second portion, and/or optionally may comprise one or more further portion(s) with a pitch and/or helix angle different to the first and second. By varying the pitch and/or helix angle along the length of the at least one helical rib it is possible to adjust the flexibility of the flexible portion of the sleeve in the axial direction. For example, the at least one helical rib may be configured so that the central portion of the flexible portion has a greater or lesser flexibility than the remainder of the helical rib.
For avoidance of doubt, the terms pitch and helix angle used herein are intended to be defined as explained below with reference to Figure 7.
The rigid portion of the sleeve may consist of a chamber portion arranged to accommodate the end of the mating portion below the radially outward shoulder, and a connecting portion defining said inlet or outlet, the connecting portion being of smaller diameter than the chamber portion.
The pipe joint may be configured such that the end of the mating portion below the radially outward shoulder moves within the chamber portion during said expansion and/or contraction, and the mating portion terminates within the chamber when the sleeve is not accommodating said expansion and/or contraction.
The outer surface of the mating portion may abut the inner surface of the chamber, thereby substantially preventing ingress of debris into the rib or ribs.
The outside diameter of the mating portion may be substantially equal to the outside diameter of the connecting portion. The outside diameter of the end of the sleeve proximate the flexible portion may be substantially equal to the outside diameter of the radially outward shoulder of the mating portion.
The flexible portion and the rigid portion of the sleeve may be materially continuous.

According to a second aspect of the invention there is provided a pipe installation comprising one or more pipe joints according to the first aspect of the invention.
The pipe installation may be arranged to receive a flow of fluid in a direction from the inlets of the one or more pipe joints towards the respective outlets of the one or more pipe joints, thereby substantially preventing the ingress of said fluid into the flexible portion of the sleeves of the one or more pipe joints.
According to a third aspect of the invention there is provided a kit of parts comprising a pipe joint according to the first aspect of the invention and at least one section of pipe for attaching to the inlet or outlet of the pipe joint.
Pipe joints according to the present invention enable expansion and contraction in soil stacks and suspended drain runs within buildings to be accommodated, with the benefit of not having any rubber seal or assemblies that could come apart. This is because joints according to the present invention are continuously jointed, and may not include or need rubber seals. This removes the requirement for separate expansion joints in a vertical and horizontal stack, as expansion joints according to the present invention become effectively materially continuous with the pipe installation.
Brief Description of the Drawings
Some embodiments of the invention will now be described by way of example only and
with reference to the accompanying drawings in which:
Figure 1 illustrates an external view of a pipe joint according to an embodiment of the
invention;
Figure 2 illustrates a cross section of a pipe joint according to an embodiment of the
invention along line A-A in Figure 1; and
Figure 3 illustrates the pipe joint of Figure 2 in an axially contracted state, i.e. when the
pipe joint is accommodating expansion within a pipe network;
Figure 4 illustrates an application of a pipe joint according to an embodiment of the
invention in part of a larger pipe installation;
Figure 5 illustrates a perspective view of a pipe joint according to a second
embodiment of the invention;

Figure 6 illustrates an external view of the pipe joint of Figure 5; and
Figure 7 illustrates a cross-section of the pipe joint of Figures 5 and 6 along the line B-
B.
Detailed Description
According to an embodiment of the invention, and with reference to Figures 1 to 4 of the drawings, a pipe joint 1 having an inlet 20 and an outlet 22 comprises: an elongate sleeve 2 having a flexible portion 3 for accommodating expansion and/or contraction between said inlet and outlet, and an axially adjacent rigid portion 4 providing one of said inlet 20 or outlet 22; and a collinear mating portion 5 providing the other of said inlet 20 or outlet 22, the mating portion 5 having means 6 for attaching to the flexible portion 3 of the sleeve 2.
According to an embodiment, both the sleeve and the mating portion are radially symmetrical and the mating portion is substantially tubular, defining the axis of the pipe joint, that being the axis of rotational symmetry of the pipe joint. In alternative embodiments, the axis may extend from the inlet to the outlet, substantially parallel to at least a portion of one or both of the sleeve and/or mating portion, but not aligned to any rotational axis of symmetry, and indeed there may be no such axis of symmetry. The means 6 for attaching the mating portion 5 to the sleeve 2 is a circumferential radially outward shoulder 6 which is located at an intermediate axial position on the mating portion 5. In this manner, as illustrated in Figure 2, the mating portion 5 may be attached to the sleeve 2 by electrofusion welding, solvent welding or butt welding the radially outward shoulder 6 to the end face 7 of the sleeve 2 in such as manner as to make a permanent, continuous joint between the two. No rubber seal may be required at the joint to make it fluid-tight. The sleeve 2 and mating portion 5 are dimensioned such that the outside diameter <))1 of the sleeve 2 at the flexible portion 3 end of the sleeve 2 is substantially the same as the outside diameter <))1 of mating portion 5 at the radially outward shoulder 6. In this manner a good fit is ensured between the mating portion 5 and the sleeve 2 around the entire circumference of the mating portion/sleeve. Other manners of attaching/affixing the mating portion 5 to the sleeve 2 are contemplated, such as clips or flanges/bolts for example. The exposed end of the mating portion, i.e. the end above the radially outward shoulder, defines the inlet 20 of the pipe joint and is generally dimensioned to correspond with a longer pipe section to

which it can be attached by any appropriate method such as electrofusion welding, for example.
With reference to Figures 2 to 4, the flexible portion 3 of the sleeve 2 consists of a number of circumferential ribs 8 distributed axially along the flexible portion 3. The ribs 8 are approximately 'IT shaped in cross section when at rest (i.e. when not under compression or tension) and allow a certain amount of axial expansion and contraction in the pipe installation 14 to be accommodated. For example, suppose axial expansion/contraction in the pipe network causes a compression force to applied to the pipe joint 1, then since the distal end of the sleeve 2, i.e. the outlet 22, may be held fixed by means of a further pipe fitting 15 or concrete slab, for example, the ribs 8 will accommodate some or all of the compression by becoming more closed at the inner side, i.e. the ribs 8 will morph towards an '0' shape or loop shape in cross section, which is illustrated in Figure 3. The opposite is the case when a tension force is applied by the pipe section 5 to the sleeve 2 via the radially outward shoulder 6, i.e. the ribs 8 will resemble a flatter 'IT shape than that which they resemble when at rest, i.e. more open than as illustrated in Figure 2, which may be indicative of the pipe joint at rest, i.e. not under tension or compression. If more ribs 8 are included in the flexible portion 3 of the sleeve 2 then more expansion/contraction can be tolerated by the pipe joint 1, since each rib 8 has a maximum compression extent and tension extend. Therefore it may be desirable to calculate the expected expansion/contraction in a given pipe installation 14 and choose a pipe joint 1 according to an embodiment of the invention which has an appropriate number of ribs 8. For example, a range of different pipe joints 1 may be provided with a range of rib 8 sizes/numbers on the sleeve 2 to suit different installation 14 scenarios. The flexible portion 3 of the sleeve 2 may also accommodate some lateral movement, e.g. resulting in the ribs on one side of the sleeve 2 being compressed whilst the ribs on the diametrically opposing side are under tension. Further, the flexible portion may allow relative rotational movement to a degree, where the inlet twists relative to the outlet, or vice versa.
As can be seen in Figure 2, the rigid portion 4 of the sleeve is composed of two regions, namely a chamber portion 9 and a connecting portion 12. The mating portion 5 is dimensioned such that when it is attached to the sleeve 2 by means of the radially outward shoulder 6, the mating portion 5 occupies the inside region of the sleeve 2 in the entire flexible portion 3 and emerges slightly into the chamber portion 9 of the rigid

portion 4 of the sleeve 3, when the pipe joint 1 is at rest, i.e. under no substantial compression or tension forces. In this manner, a small overlap/abutment 10 arises between the outside wall of the mating portion 5 and the inside wall of the chamber portion 9, which creates a barrier against debris ingress into the ribs 8. When expansion/contraction in the pipe network causes a compression force to be applied to the pipe joint 1, the end of the mating portion 5 within the sleeve 2 will move further into the chamber portion 9. The limit of movement in this direction is governed by the axial extent 11 of the chamber portion 9. Beyond the chamber portion 9 the internal/outside diameter of the rigid portion 4 of the sleeve 2 decreases into the connecting portion 12 which defines the outlet of the pipe joint 1. In this manner, there is an internal shoulder 13 against which the end face of the mating portion 5 will abut under maximum compression of the ribs 8. The outside diameter <))2 of the connecting portion 12 is substantially the same as the outside diameter <))2 of the mating portion 5 which in turn may be substantially the same as the outside diameter of a pipe section 16 which is to be joined to the inlet of the pipe joint 1, such that any fittings 15 which are compatible with the pipe section 16 are also compatible with pipe joint 1 as whole including the sleeve 2. The flexible portion 3 and the rigid portion 4 are materially continuous. The sleeve 2 and mating portion 5 may be formed of any suitable material such as polyvinyl chloride or high-density polyethylene, for example.
Although in the above-described embodiment the sleeve surrounds part of the mating portion, in alternative embodiments the sleeve may in fact be disposed partially within the mating portion. For example, in this alternative embodiment the ribs of the flexible portion of the sleeve may extend radially inwards, rather than radially outwards as illustrated. Thus the term "sleeve" as used herein is not to be interpreted as being limited to an outer-most component, and as such the sleeve could either be an inner or outer sleeve, with the mating portion disposed either outside or inside of the sleeve, respectively.
With reference to Figure 4, the pipe joint 1 is installed in a pipe installation 14 comprising a longer pipe section 16 such that the direction of flow of fluid through the joint 1 is in the direction indicated in Figures 2 and 4, i.e. in the direction going from the flexible portion 3 of the sleeve 2 towards the rigid portion 4 of the sleeve 2 (i.e. from the inlet to the outlet of the pipe joint 1). In this manner, since the mating portion 5 downstream of the shoulder 6 occupies the inside region of the sleeve 2 along the

8
entire length of the flexible portion 3, the ribs 8 are substantially shielded from the fluid which is flowing in the indicated direction and therefore debris cannot build up or become caught in the ribs 8, which if allowed to happen would limit the amount of expansion/contraction the ribs could accommodate and ultimately render the joint ineffective at accommodating expansion/contraction. Furthermore, as mentioned above, the small overlap 10 between the outside wall of the mating portion 5 and the inside wall of the chamber portion 9, completes the barrier against debris ingress into the ribs 8.
The longer section of pipe 16 is joined to the inlet 20 of the pipe joint 1 by e.g. electrofusion welding. Alternatively, the longer section of pipe 16 and the mating portion 5 could effectively be one and the same component, i.e. they could be materially continuous. In such a case, the longer section of pipe 16 may initially be a standard section of pipe without the radially outward shoulder 6. Some form of ring may then be affixed (e.g. by solvent welding) to the outer surface of the pipe 16 at an appropriate location thereby effectively turning the plain pipe section into the combined pipe section and mating portion. Thus there is great flexibility in how the overall concept of the pipe joint 1 as herein described is incorporated into a pipe installation.
The pipe joint 1 may be used to accommodate expansion and contraction in soil stacks and suspended drainage runs within buildings. A sufficient number of anchor and guide points would be provided throughout the building to support the system, with all expansion and contraction being accommodated at the or each pipe joint 1.
Turning now to Figures 5 to 7, there is shown a second embodiment of the invention. The pipe joint 100 is substantially the same as the pipe joint 1 in Figures 1 to 4, and descriptions of the features in common will not be repeated. The pipe joint 100 differs from the pipe joint 1 of the first embodiment by having a single helical rib 108, rather than the multiple concentric ribs 8 of the first embodiment.
The pipe joint 100 has a flexible portion 103 which is defined by the length of the helical rib 108. It will be understood that the end of the flexible portion 103 adjacent to the outlet 122 will have a small section of the circumference free of the helical rib 108 due to the shape of the helix.
9

The means for attaching the mating portion 105 to the sleeve 102 is a circumferential radially outward shoulder 106 which is located at an intermediate axial position on the mating portion 105. The shoulder 106 projects further from the surface of the mating portion 105 compared to the pipe joint 1 in Figures 1-4. The sleeve 102 is provided with a sealing portion 107 which has the same width/diameter as the outer surface of the helical rib 108. Thus, the shoulder 106 and sealing portion 107 have the same dimensions and can abut. The mating portion 105 may be attached to the sleeve 102 by any suitable method such as electrofusion welding, solvent welding or butt welding (as described previously) between the radially outward shoulder 106 and the sealing portion 107. Thus a permanent, continuous joint can be made between the two. No rubber seal is necessary at the joint to make it fluid-tight.
The pipe joint 100 has been found to have increased flexibility compared to the pipe joint 1 of Figures 1 to 4. The flexibility of the pipe joint 100 can be configured by varying the dimensions and characteristics of the helical rib 108. For example, the pitch P of the helical rib 108 is the axial distance required for one complete turn of the helix. The helix angle 9 is the angle between the helical rib 108 and the axis of the helix. The pitch P and helix angle 9 can be increased or decreased as desired to modify the flexibility with a similar effect to changing the width in the axial direction and total number of the concentric ribs 8 of the pipe joint 1 of the first embodiment.
The pipe joint 100 can be used in exactly the same way as the pipe joint 1 of Figures 1 to 4, including within installations as described with reference to Figure 4. A further advantage of the helical rib 108 is the simplified manufacture of the flexible portion of the sleeve. For example, when moulding the sleeve 102, the completed product can be simply unscrewed from the mould, making removal easier and quicker and reducing breakages.
It will be appreciated by the person of skill in the art that various modifications may be made to the above described embodiments without departing from the scope of the present invention.

We Claim:

1.A pipe joint having an inlet and an outlet, the pipe joint comprising:
an elongate sleeve having a flexible portion for accommodating expansion and/or contraction between said inlet and outlet, and an axially adjacent rigid portion providing one of said inlet or outlet; and
a mating portion providing the other of said inlet or outlet, the mating portion having means for attaching to the flexible portion of the sleeve.
2. The pipe joint according to claim 1, wherein said expansion and contraction are substantially along an axis extending from the inlet to the outlet.
3. The pipe joint according to claim 1 or 2, wherein an axis of the sleeve and an axis of the mating portion are substantially parallel.
4. The pipe joint according to claim 3, wherein the sleeve and the mating portion are substantially coaxial.
5. The pipe joint according to claim 3 or 4, wherein the mating portion has a radially outward shoulder for attaching the mating portion to the flexible portion of the sleeve.
6. The pipe joint according to claim 5, wherein the radially outward shoulder is arranged to be electrofusion welded, solvent welded or butt welded to the flexible portion of the sleeve.
7. The pipe joint according to claim 5 or 6, wherein the mating portion is substantially tubular, and the sleeve is substantially radially symmetrical.
8. The pipe joint according to claim 7, wherein the radially outward shoulder is located at an intermediate axial position on the mating portion such that the mating portion extends partially into the sleeve when the mating portion is attached to the sleeve by means of the radially outward shoulder, and wherein the end of the mating portion above the radially outward shoulder defines said inlet or outlet.

9. The pipe joint according to claim 8, wherein the flexible portion of the sleeve comprises one or more radially outward extending circumferential ribs, the ribs being configured to accommodate said expansion and/or contraction.
10. The pipe joint according to claim 9, wherein the one or more circumferential ribs surround the part of the mating portion below the radially outward shoulder which extends into the sleeve.
11. The pipe joint according to claim 10, wherein the rigid portion of the sleeve consists of a chamber portion arranged to accommodate the end of the mating portion below the radially outward shoulder, and a connecting portion defining said inlet or outlet, the connecting portion being of smaller diameter than the chamber portion.
12. The pipe joint according to claim 11, configured such that the end of the mating portion below the radially outward shoulder moves within the chamber portion during said expansion and/or contraction, and the mating portion terminates within the chamber when the sleeve is not accommodating said expansion and/or contraction.
13. The pipe joint according to claim 12, wherein the outer surface of the mating portion abuts the inner surface of the chamber, thereby substantially preventing ingress of debris into the ribs.
14. The pipe joint according to any one of claims 11 to 13, wherein the outside diameter of the mating portion is substantially equal to the outside diameter of the connecting portion.
15. The pipe joint according to any one of claims 11 to 14, wherein the outside diameter of the end of the sleeve proximate the flexible portion is substantially equal to the outside diameter of the radially outward shoulder of the mating portion.
16. The pipe joint according to any preceding claim, wherein the flexible portion and the rigid portion of the sleeve are materially continuous.
17. A pipe installation comprising one or more pipe joints according to any preceding claim.

18. The pipe installation according to claim 17, arranged to receive a flow of fluid in a direction from the inlets of the one or more pipe joints towards the respective outlets of the one or more pipe joints, thereby substantially preventing the ingress of said fluid into the flexible portion of the sleeves of the one or more pipe joints.
19. A kit of parts comprising a pipe joint according to any one of claims 1 to 16 and at least one section of pipe for attaching to the inlet or outlet of the pipe joint.