GB2331137A

GB2331137A - Non-stick jointing ring or gasket

Info

Publication number: GB2331137A
Application number: GB9824022A
Authority: GB
Inventors: Thomas William Wildgoose
Original assignee: Glynwed Pipe Systems Ltd
Current assignee: Glynwed Pipe Systems Ltd
Priority date: 1997-11-08
Filing date: 1998-11-04
Publication date: 1999-05-12
Also published as: GB9824022D0; GB9723561D0; AU1040499A; WO1999024750A1

Abstract

A jointing ring or gasket 1 for or included in a pipe, or a pipe joint, comprises a part 4 including an integral non-stick solid material 12 which provides the part with a low friction surface. The ring or gasket may be used in a spigot 14 and socket 10 pipe joint with the part of non-stick material contacting either the spigot 14 or socket 10. There may be more than one such part. Another application of the ring or gasket is around a segment for a pipe-like structure (Figure 4). The non-stick material may be applied as a coating to the or each part after the part has been formed, or it may be included in the jointing ring or gasket as it is formed. Preferably the non-stick material (12) is a plastics material, e.g. a fluoropolymer, which has low friction characteristics and is flexible, such as polytetrafluoroethylene (PTFE).

Description

JOINTING RING OR GASKET AND JOINTS INCORPORATING THE SAME This invention relates to jointing rings or gaskets for pipes, and joints incorporating jointing rings or gaskets.

The invention has relevance, but not exclusively, to jointing rings or gaskets for providing a seal in a pipe joint of the spigot and socket kind. Such rings or gaskets are usually made of an elastomeric material.

It is to be understood that the expression "pipe" as used herein is intended to include pipes and tubes as such, and also pipe-like fittings used within pipework such as elbows, 'T' bends and valves incorporated in pipe work and having parts of a pipe-like nature, and pipe-like structures such as tunnels, shafts or linings assembled from segments, such as made as concrete castings, which fit together and are sealed, for example against water ingress, at their joints by gaskets applied to the segments.

Joints of the above-mentioned spigot and socket kind are utilised in the inter-connection of pipes of water or gas carrying capability, for example, and comprise a socket at one end of a pipe within which is located an annular jointing ring or gasket which is sealingly engageable with a spigot of the next adjacent pipe on insertion into the socket so as to provide a sealed joint. As a jointing ring or gasket which provides a seal in such a joint must have good sealing contact with the socket and spigot at a joint, force is required to engage the spigot in the jointing ring or gasket. Without application of lubrication the force required can be quite substantial. The force required can be reduced appreciably by the application of lubrication to the jointing ring or gasket. The conventional way of lubricating a jointing ring or gasket is to apply a coating of a liquid soap solution, usually by brush, on the jointing ring or gasket. A problem with this is that in many working situations where pipe joints have to be made, for example outdoors in dug trenches, there is a strong likelihood of the coated jointing ring or gasket becoming soiled with dirt, debris, grit or other foreign matter from the surroundings, which sticks to the soap solution before the joint is made. That soiling can reduce the effectiveness of the lubrication and, more seriously, it can result in an unsatisfactory seal being produced at the pipe joint. Apart from that the process of applying the coating to the jointing ring or gasket takes time, involves additional equipment to be used by the pipe fitter and tends to be messy.

In the case of segments for the construction of pipe-like structures, the segments are each shaped to form part of the required circumferential shape. They are assembled and secured together to make up the circumferential shape. Gaskets are provided around the peripheries of the segments to seal adjacent segments together, the gaskets usually being located and bonded in grooves in the peripheries and extending continuously, like frames, around the peripheries. It is usually essential that good sealing contact is made between the gaskets of adjacent segments but it can happen that the gaskets can be moved and even become detached from the grooves as segments are manoeuvred into position, and adjusted so that seals are not properly made. The elastomeric material of which the gaskets are made has a tendency to develop a high friction condition so that when adjacent gaskets are brought together they are likely to adhere to one another and relative movement then between their respective segments can break the bonding of the gaskets in their grooves, and even cause the gaskets to become detached from the grooves. As an aid to preventing this, lubrication is applied to the gaskets to enable them to slip over one another as the segments are moved, the lubrication conventionally being a liquid soap solution such as used for the spigot and socket kind of joint described above, and similarly applied usually by brush. Similar problems arise from the use of that lubrication.

The present invention seeks to avoid the above-mentioned shortcomings associated with the conventional lubrication of jointing rings or gaskets.

According to a first aspect of the present invention there is provided a jointing ring or gasket for a pipe having a part including an integral non-stick solid material which provides the part with a low friction surface.

According to a second aspect of the present invention there is provided a joint which includes a jointing ring or gasket in accordance with the foregoing first aspect of the present invention disposed between connected components of the joint.

When the jointing ring or gasket is to be used for a spigot and socket pipe joint the part of non-stick material may be an approach part at which the ring or gasket is introduced to the spigot or socket for engagement therewith.

If the jointing ring or gasket is to be applied to a segment for a pipe-like structure, the part or parts which are to make contact with another segment, or other segments, with which the segment is to be assembled may be of the non-stick material.

Preferably the non-stick material is a plastics material which has low friction characteristics and is flexible. The material may be a fluoropolymer, typically a polytetrafluoroethylene (PTFE) such as TEFLON (Registered Trade Mark).

The non-stick material may be applied as a coating to the formed part of the jointing ring or gasket. The coating may be applied in liquid form, for example by brushing, dipping or spraying, and then be baked to become a solid integral surface of the part. Alternatively, the non-stick material may be included in the jointing ring or gasket as the ring or gasket is formed. Thus when the jointing ring or gasket is made as a moulding, of an elastomeric material, the non-stick material may be included in the ring or gasket as it is moulded. If the jointing ring or gasket is made at least partially as an extrusion the non-stick material may be included by spraying it onto the extrusion or possibly by co-extrusion.

The remainder of the jointing ring or gasket may be made of any suitable material. It may be made of an elastomeric material, rubber or a mouldable polymeric material, such as commonly used for jointing rings or gaskets. The jointing or gasket ring may include a holding ring, in accordance with the jointing gasket provided in our GB Patent Application 97150775, or a resilient holding ring, such as a spring, in accordance with the jointing ring provided in our GB Patent Application 9716144.2.

The jointing ring or gasket may be of a torodial form or it may be of a generally sleeve-like form. The part of non-stick material may be inclined or ramped.

For a spigot and socket pipe joint the part may comprise a flared mouth of the jointing ring or gasket, for example, or an internal flap, flange or other sealing portion which may be bodily inclined or have an inclined surface for sealing engagement with the spigot. Another possibility is for the part to be a ramped part at the exterior of the jointing ring or gasket, or an external flap, flange or other sealing portion which may be bodily inclined or have an inclined surface for sealing engagement with the socket. There may be two of the parts, one for engagement with the spigot and the other for engagement with the socket.

The jointing ring or gasket may be fitted as an original part of a pipe manufactured to be connected to another pipe by a spigot and socket joint. It may be fitted as an original part of a segment manufactured for use in a pipe-like structure.

According to a third aspect of the present invention a pipe is provided having a socket in which is located a jointing ring or gasket in accordance with the foregoing first aspect of the invention the part of which of non-stick material is disposed to be introduced to a spigot of a second pipe for reception of the spigot into the socket to form a sealed joint between the pipes.

According to a fourth aspect of the present invention a pipe is provided having a spigot on which is located a jointing ring or gasket in accordance with the foregoing first aspect of the invention the part of which of non-stick material is disposed to be introduced to a socket of a second pipe for the socket to receive the spigot to form a sealed joint between the pipes.

According to a fifth aspect of the present invention a segment for a pipe-like structure is provided having located thereon a jointing ring or gasket in accordance with the foregoing first aspect of the invention the part of which of non-stick material is disposed for contact with a jointing ring or gasket of another segment.

The jointing ring now provided facilitates the making of a joint between pipes or segments. Tests have been carried out using a jointing ring or gasket in accordance with the first aspect of the invention located in the socket of a first pipe and having a part with an integral PTFE coating for the introduction of the spigot of a second pipe into the jointing ring or gasket and socket. These tests showed that the force required to insert the spigot through the jointing ring or gasket and the socket was only about one third of that required to make such a joint with a similar type of known jointing ring or gasket devoid of a non-stick material and without having a lubricant applied to it. The reduced force required was comparable to that needed when a liquid soap lubricating solution is applied in the conventional way. The jointing ring or gasket now provided, however, has the advantages over the known rings or gaskets lubricated with a liquid soap solution that it is cleaner to use, there is no need for the fitter to apply a lubricant and there is considerably less risk of the jointing ring or gasket becoming soiled by dirt or other foreign matter at the working situation where the joint is made. If a pipe or segment is supplied to site already fitted with the jointing ring or gasket the joining of the pipe to, or the assembling of the segment with, another is facilitated further.

Some embodiments of the invention are shown by way of example only in the accompanying drawings, in which: Figures 1 and 2 are fragmentary sections through two different spigot and socket pipe joints, each shown separated, in the sockets of which jointing rings in accordance with the first aspect of the invention are located; Figure 3 is a fragmentary section through a further spigot and socket pipe joint, also shown separated, in which a jointing ring in accordance with the first aspect of the invention is located on the spigot, and Figure 4 is a perspective view of a segment for tunnel construction including a jointing gasket in accordance with the first aspect of the invention.

In the embodiments illustrated by Figures 1 to 3 the jointing rings 1 have annular bodies 2 made as mouldings of a resilient elastomeric material such as natural or synthetic rubber.

Referring to Figure 1, the jointing ring 1 has its annular body 2 of a generally wedge-shaped section having a cylindrical external surface 3 and an inclined internal surface 4 which inclines inwardly from a forward, entry, end 5 of the jointing ring, thereby increasing the thickness of the section towards a rearward end 6 of the ring. An annular helically coiled spring 7 is contained within the thicker part of the section of the body 2 towards the rearward end 6. Adjacent to the forward end 5 an annular rib 8 projects from the external surface 3 and engages in an annular internal groove 9 in a socket 10 of a first pipe 11 to locate the jointing ring in the socket, near to the mouth of the socket.

The inclined surface 4, which constitutes an approach part of the jointing ring, has a coating 12 of PTFE applied to it. The PTFE is sprayed onto the inclined surface and then baked so that it is solid, yet flexible, and becomes an integral part of the body 2 of the jointing ring.

This is done in the course of manufacture of the jointing ring before it is located in the socket of the first pipe 11. With the PTFE coating 12 the inclined surface 4 becomes a low friction surface.

The first pipe 11 is joined to a second pipe 13 by pushing a spigot 14 of the latter into the socket 10 of the first pipe through the jointing ring. As the spigot is inserted a bevelled end edge 15 of the spigot engages with the inclined surface 4 of the jointing ring and the PTFE coating 12 allows the spigot to pass through the ring without excessive force being necessary. The body 2 becomes resiliently compressed as the spigot is pushed through the jointing ring and a good seal is thus achieved at the joint.

In the embodiment of Figure 2 the jointing ring 1 has its annular body 2 of a generally triangular section with the base thereof presenting a cylindrical internal surface 16 of the body. An inwardly inclined sealing flap 17 projects from the internal surface 16, being joined to the body for approximately half of its axial length from a forward, entry, end 18 of the jointing ring. A forwardly directed surface 19 of a sealing flap 17 constitutes an approach part of the jointing ring and has a coating 20 of PTFE applied to it in similar manner to the coating 12 in the first described embodiment.

The triangular section body 2 engages in a complementary internal recess 21 formed in a socket 22 of a first pipe 23 so as to locate the jointing ring 1 in the socket, the sealing flap 17 projecting into the bore of the socket 22 with the coated forwardly directed surface 19 facing the mouth of the socket.

As before, a spigot 24 of a second pipe 25 to be joined to the first pipe 23 is pushed into the socket 22 of the first pipe through the jointing ring 1, a bevelled end edge 26 of the spigot 24 engaging with the forwardly directed surface 19 of the sealing flap 17. The PTFE coating 20 allows the spigot to pass readily through the jointing ring to make the joint. As the spigot 24 passes through the jointing ring, the sealing flap 17 is resiliently urged outwardly into compressive engagement with the cylindrical internal surface 16 of the body 2 so that a good seal is again provided at the joint.

Referring now to Figure 3, in this embodiment the jointing ring 1 has its annular body 2 of a generally wedge -shaped section which is inside out as compared with the body of the jointing ring in the first described embodiment. Here the body 2 has a cylindrical internal surface 27 and an inclined external surface 28 which inclines outwardly from a forward end 29 of the jointing ring. The inclined external surface 28 is rounded towards the thicker rearward portion of the body 2.

The inclined external surface 28 constitutes an approach part of the jointing ring and has a PTFE coating 30 applied to it, in a similar manner to the PTFE coatings of the other two embodiments.

To make a joint between a first pipe 31 and a second pipe 32 the jointing ring is located in an external annular groove 33 in a spigot 34 of the first pipe. The inclined external surface 28 of the located jointing ring projects from the groove 33. As the spigot 34 is pushed into a socket 35 of the second pipe 32, the inclined external surface 28 of the jointing ring engages with an internally bevelled edge 36 of the mouth of the socket and the body of the jointing ring becomes compressed as the ring is pushed with the spigot into the socket. The PTFE coating 30 on the inclined external surface 28 allows the jointing ring to enter with relative ease into the socket but the compression of the body of the inserted jointing ring provides a good seal between the two joined pipes.

Referring now to Figure 4, a segment 37 is shown, made for example as a concrete casting, which is intended for use in the construction of a tunnel. The segment 37 is of arcuate rectangular shape and assembles with others, as indicated at 37', 37", 37"', 37"", circumferentially and axially to form a required tunnel structure. It has a flanged periphery 38 at which it is bolted to the adjacent segments.

Extending along all four side edges of the periphery 38 of the segment 37 is a peripheral groove 39. Located in the groove 39 is sealing gasket 40 which is in one-piece and four-sided to extend all around the periphery of the segment. The sealing gasket 40 is made from an extrusion of a resilient elastomeric material, such as natural or synthetic rubber. Its cross-section is of a width to fit tightly in the groove 30 and it is of a depth to protrude out of the groove. The protruding part 41 has a coating 42 of PTFE applied to it, the PTFE being sprayed on and then baked to become solid and an integral part of the gasket. Thus the PTFE coating 42 provides the protruding part 41 with a low friction surface.

The PTFE coating is applied in the course of manufacture of the gasket before the gasket is attached to the segment 37.

The gasket 40 is sufficiently resilient to enable it to be engaged in the groove 39, where it contracts to engage tightly in the groove.

Adhesive secures the gasket in the groove.

In the construction of a tunnel the segment is located edge to edge axially and circumferentially with other segments 37', 37'', 37''', 37' also fitted with similar gaskets to seal the segments together in the structure. The PTFE coating 42 of the gasket and of the gaskets of the other segments enables the gaskets to slip easily over one another as the segments are manoeuvred into position, and adjustments of their positions are made to ensure their proper location. This facilitates appreciably the assembling of the segments and avoids movements of the gaskets relative to their respective segments, and possible undesirable detachment of gaskets from the grooves in the segments.

Claims

CLAIMS 1. A jointing ring or gasket for a pipe having a part including an integral non-stick solid material which provides the part with a low friction surface.
2. A jointing ring or gasket according to claim 1 wherein the part of non-stick material is an approach part at which the ring or socket is introduced to a spigot or socket of a pipe for engagement therewith.
3. A jointing ring or gasket according to claim 1 which is made to be applied to a segment for a pipe-like structure and the part of non-stick material is at least one part of the ring or gasket which is to make contact with the segment or segments with which the segment is to be assembled to form the pipe-like structure.
4. A jointing ring or gasket according to any preceding claim wherein the non-stick material is a plastics material which has low friction characteristics and is flexible.
5. A jointing ring or gasket according to claim 4 wherein the plastics material is a fluoropolymer.
6. A jointing ring or gasket according to claim 5 wherein the plastics material is polytetrafluoroethylene.
7. A jointing ring or gasket according to any preceding claim wherein the non-stick material is applied as a coating to said part after the part has been formed.
8. A jointing ring or gasket according to any of claims 1 to 6 wherein the non-stick material is included in said part as the ring or gasket is formed.
9. A jointing ring or gasket according to claim 8 which is made as a moulding.
10. A jointing ring or gasket according to claim 8 which is made at least partially as an extrusion, the non-stick material being included by spraying it onto the extrusion.
11. A jointing ring or gasket according to claim 8 which is made at least partially as an extrusion, the non-stick material being included as a co-extrusion with the extrusion.
12. A jointing ring or gasket according to any preceding claim wherein except for the non-stick material the ring or gasket is made of an elastomeric material.
13. A jointing ring or gasket according to any preceding claim which includes a holding ring.
14. A jointing ring or gasket according to claim 13 wherein the holding ring is resilient.
15. A jointing ring or gasket according to claim 14 wherein the holding ring is a spring.
16. A jointing ring or gasket according to any preceding claim which is of a toroidal form.
17. A jointing ring or gasket according to any of claims 1 to 15 which is of a generally sleeve-like form.
18. A jointing ring or gasket according to any preceding claim wherein the part of non-stick material is inclined or ramped.
19 A jointing ring or gasket according to claim 2 or any of claims 4 to 18 as dependent from claim 2 wherein the part of non-stick material is a flared mouth of the ring or gasket.
20. A jointing ring or gasket according to claim 18 as dependent from claim 1 or any of claims 4 to 17 which is made to be used in a spigot or socket pipe joint and wherein the part of non-stick material is an internal flap, flange or other sealing portion which is bodily inclined or has an inclined surface for sealing engagement with the spigot of the pipe joint.
21. A jointing ring or gasket according to claim 18 as dependent from claim 1 or any of claims 4 to 17 which is made to be used in a spigot or socket pipe joint and wherein the part of non-stick material is a ramped part at the exterior of the ring or gasket, or an external flap, flange or other sealing portion which is bodily inclined or has an inclined surface for sealing engagement with the socket of the pipe joint.
22. A jointing ring or gasket according to claims 20 and 21 which has two of said parts of the non-stick material, the one part being that which has sealing engagement with the spigot of the pipe joint and the other part being that which has sealing engagement with the socket of the pipe joint.
23. A pipe joint including a jointing ring or gasket as claimed in any preceding claim disposed between connected components of the joint.
24. A pipe including a jointing ring or gasket as claimed in any of claims 1 to 22.
25. A pipe having a socket in which is located a jointing ring or gasket as claimed in any of claims 1 to 22 the part of which of non-stick material is disposed to be introduced to a spigot of a second pipe for reception of the spigot into the socket to form a sealed joint between the pipes.
26. A pipe having a spigot on which is located a jointing ring or gasket as claimed in any of claims 1 to 22 the part of which of non-stick material is disposed to be introduced to a socket of a second pipe for the socket to receive the spigot to form a sealed joint between the pipes.
27. A segment for a pipe-like structure having located thereon a jointing ring or gasket as claimed in claim 3 or any of claims 4 to 18 the part of which of non-stick material is disposed for contact with a jointing ring or gasket of another segment.
28. A jointing ring substantially as described herein with reference to Figure 1 of the accompanying drawings.
29. A jointing ring substantially as described herein with reference to Figure 2 of the accompanying drawings.
30. A jointing ring substantially as described herein with reference to Figure 3 of the accompanying drawings.
31. A jointing gasket substantially as described herein with reference to Figure 4 of the accompanying drawings.
32. A spigot and socket pipe joint substantially as described herein with reference to Figure 1 of the accompanying drawings.
33. A spigot and socket pipe joint substantially as described herein with reference to Figure 2 of the accompanying drawings.
34. A spigot and socket pipe joint substantially as described herein with reference to Figure 3 of the accompanying drawings.
35. A segment for a tunnel construction including a jointing gasket, substantially as described herein with reference to Figure 4 of the accompanying drawings.