GB2293422A

GB2293422A - A method of joining a conduit to a second conduit and a seal

Info

Publication number: GB2293422A
Application number: GB9419276A
Authority: GB
Inventors: Phillip Ryan; Robert Michael O'keefe
Original assignee: Johnston Pipes Ltd
Current assignee: Johnston Pipes Ltd
Priority date: 1994-09-23
Filing date: 1994-09-23
Publication date: 1996-03-27
Anticipated expiration: 2014-09-23
Also published as: GB2293422A8; GB2293422B; GB9419276D0

Abstract

The present invention relates to (with reference to Figure 2) a method of joining a first conduit to a second conduit in a branch connection comprising the steps of: creating an aperture in a wall of the first conduit, inserting compliant sealing means (10) into the aperture, inserting the second conduit into the aperture, and compressing at least a portion (14) of the sealing means (10) located between the first and second conduits in order that the sealing means (10) sealingly locates the second conduit in the aperture. The present invention also relates to a seal (10) for use in an aperture in a first conduit or in a container which in use acts between a surface defining the aperture and a second conduit in order to sealingly locate the second conduit in the aperture. The seal (10) comprises a first compliant part (11) and a second less compliant part (12) which are arranged such that at least a portion (14) of the first compliant part (11) is compressed between the surface defining the aperture and the second less compliant part (12) when the seal (10) is inserted into the aperture. <IMAGE>

Description

A METHOD OF JOINING A CONDUIT TO A SECOND CONDUIT AND A SEAL The present invention relates to a method of joining a first conduit to a second conduit in a branch connection. The present invention also relates to a seal, which is suited to use in the method but also is of general utility.

In the prior art a branch connection between a concrete host pipe and a clay branch pipe is typically manufactured by casting a piece of clay pipe into the concrete pipe. This method is time consuming, prone to error and creates a product which is easy to damage and difficult to repair.

The present invention provides in a first aspect a method of joining a first conduit to a second conduit in a branch connection comprising the steps of: creating an aperture in a wall of the first conduit, inserting compliant sealing means into the aperture, inserting the second conduit into the aperture, and compressing at least a portion of the sealing means located between the first and second conduits in order that the sealing means sealingly locates the second conduit in the aperture.

The invention provides an easy, straightforward method of joining a first conduit to a second conduit in a branch connection, e.g. a concrete host pipe with a clay branch pipe. The resulting joints are not fragile and joints can be manufactured in situ wherever required.

The present invention provides in a second aspect a seal for use in an aperture in a first conduit or container which in use acts between a surface defining the aperture and a second conduit in order to sealingly locate the second conduit in the aperture, wherein the seal comprises a first compliant part and a second less compliant part which are arranged such that at least a portion of the first compliant part is compressed between the surface defining the aperture and the second less compliant part when the seal is inserted into the aperture.

The invention also provides a seal which can be used in many applications to provide an effective fluidtight connection, e.g. to locate a pipe in an aperture in another pipe or in an aperture in a container. The seal is particularly suited for use in sealing between a concrete host pipe and a clay branch pipe since clay branch pipes are not generally made to strict tolerances and it can be found that the annular clearance between a concrete host pipe and a clay branch pipe is too great for a normal seal of one part construction to be sufficiently compressed between the branch pipe and the host pipe. The two part seal overcomes this problem.

It should be understood that when reference is made in the description and in the claims to a "first compliant part" and a "second less compliant part", the two parts could be both of the same material, but given different compliances by virtue of, for instance, different densities. For instance, it is envisaged that a seal could be moulded from a particular compound in a mould with the moulding process adapted to give different densities to give two different parts integrally within the seal.

A preferred embodiment of the method of the invention and a preferred embodiment of seal according to the present invention will now be described with reference to the accompanying drawings, in which; Figure 1 is an elevational view of a seal according to the invention; Figure 2 is a cross-sectional view through the seal of Figure 1, the cross-section taken along the line A-A of Figure 1.

Figure 3 is a cross-sectional view through one half of a second embodiment of seal according to the invention.

Figure 4 is a cross-sectional view through one half of a third embodiment of seal according to the invention.

Figure 5 is a cross-sectional view through one half of a fourth embodiment of seal according to the invention.

Figure 6 is a cross-sectional view through one half of a fifth embodiment of seal according to the invention.

Referring to both Figures 1 and 2 a seal 10 according to the present invention comprises a first compliant part in the form of member 11 and a less compliant part in the form of member 12. The seal 10 is designed to fit in an aperture in a wall of a conduit (e.g. a water soil pipe) or a container.

The member 11 of the seal 10 would typically be of polyurethane or rubber and the type of material for the member 11 will be chosen to suit a particular application. For instance a chemically resistant rubber may be chosen when the seal 10 will be exposed to corrosive conditions. In the described preferred embodiment the member 11 is a rubber member 11 of EPDM with a shore hardness of 50. The member 12 is plastic and is chosen to be less compliant than the rubber member 11.

The rubber member 11 of the seal 10 is circular and surrounds the plastic member 12. The rubber member 11 has a flange 13 at its front end (i.e. the end which is exposed when the seal 10 is located in an aperture) which extends radially outwardly of the rubber member 11. The rubber member 11 also has an outwardly protruding annular rib 14 provided on its exterior surface spaced apart from the flange 13.

When the seal 10 is in an aperture in a conduit or container the flange 13 and annular rib 14 act together to grip the wall of a conduit or container and to hold the seal 10 in place in the aperture; the annular rib being compressed between the wall of the conduit or container and the plastic member 12.

The rubber member 11 of the seal 10 has two inwardly facing ribs 15 and 16 spaced apart from each other. The rib 15 is nearest the flange 13 which is at the front end of the seal 10, i.e. the end that is outside of the conduit or container when in use and which is the entry point for the seal 10. The rib 15 has a cross-section which is in shape a right-angled triangle, the rib 15 having a surface 15a which is a tapering surface and which faces the front end of the seal 10 and a flat surface 15b which is in a plane transverse of the seal 10 and which faces the rear end 10b of the seal 10. The second rib 16 has a crosssection which is an isosceles triangle, the rib 16 having two inclined surfaces 16a and 16b respectively facing the front end 10a and rear end 10b of the seal 10.

The plastic member 12 has three distinct portions, a portion 12a nearest the front end 10a of the seal 10, a portion 12b at the rear end of the plastic member 12 and an intermediate portion 12c.

The plastic member 12 has a uniform external diameter Dl along its length. The portion 12a has an inner radius D2 and the portion 12c has a lesser diameter D3.

The portion 12b is an inwardly extending flange at the rear of the plastic part 13. The portion 12a of the plastic member 12 is sandwiched between two layers of the rubber member 11. The portion 12a underlays the two ribs 15 and 16. The rubber member 11 has an inwardly extending rear flange 17 which abuts and covers the rear facing surface of the flange 12c. The rear flange 17 acts to securely locate the plastic member 12 in the rubber member 11. The flange 12c and the flange 17 together define a rear aperture 18 of the seal 10. The annular rib 14 overlays the plastic member 12.

An example of how the preferred seal 10 can be used in a method according to the present invention will now be given.

A circular cross-section Hepworth clay branch pipe is to be joined to a circular cross-section concrete host pipe in a branch connection. A circular aperture is drilled in the wall of the concrete host pipe to receive the Hepworth clay branch pipe. The seal 10 described above is inserted into the drilled aperture, with the wall of the concrete host pipe gripped between the flange 13 and the rib 12 and a portion of the rubber member 11 which overlays the plastic member 12 (which portion includes at least a part of rib 14) being compressed between the surface of the concrete pipe defining the aperture and the plastic member 12. The seal 10 is thus securely located in the aperture in the concrete pipe, with the flange 13 serving to prevent the branch pipe from being pushed too far into the host pipe.

The smooth-walled Hepworth clay branch pipe is pushed into the seal 10 until the end of the branch pipe abuts the flange 12c of the plastic member 12 of the seal 10; the flange 12c acts as a stop in order to prevent the branch pipe from being pushed too far into the aperture in the concrete host pipe.

The seal 10 sealingly locates the branch pipe in the aperture in the concrete pipe. The flange 13, the rib 14 and a portion lla of the rubber member 11 (which extends between the rib 12 and the flange 13) all engage the material of the host pipe to form a leaktight seal. The ribs 15 and 16 of the rubber part 12 engage the outer surface of the branch pipe to form a leaktight seal.

The plastic member 12 of the seal 10 serves to allow compression of the portion of the rubber member 13 which is located between the plastic part 12 and the host pipe. This compression enables secure fixed location of the seal 10 in the aperture in the host pipe and permits good sealing around the aperture.

The clay pipes generally available are not manufactured to strict tolerances and thus quite a large annular gap can exist between the exterior of a clay pipe and the inwardly facing surface of the drilled aperture in the host pipe. A large annular gap does not provide good compression of a sealing member between the concrete host pipe and the branch pipe; this problem is overcome by the plastic member 12 providing a firm support for the rubber member 11.

The rib 15 of the rubber member 11 of the seal 10 ensures a good seal around the surface of the branch pipe. The rib 16 seals around the branch pipe and also helps to prevent a lateral load on the branch pipe creating a leak by resisting shear loading on the branch pipe and thus preventing pivoting of the branch pipe in the seal 10. The rib 15 is of slender section and will not be able to resist shear loading. For this reason the second rib 16 is provided. The performance of the rib 16 is enhanced by the firm support of the plastic member 12 which is advantageously positioned to allow compression of the rib 16 between the clay branch pipe and the plastic member 12.

Whilst in the seal 10 described above the rubber member 11 has a portion 17 which covers the rear surface of the flange 12b and serves to prevent the plastic member 12 moving relative to the rubber member 11, this is not necessary as can be seen from figure 3 where a second embodiment of seal is shown. In figure 3 a seal 30 has a rubber member 31 which is identical to the rubber member 11 already described except that it does not have the inwardly extending rear flange 17. The plastic member 32 of the seal 30 is identical to the plastic member 12 already described except that it has a triangular cross-section outwardly projecting rib 33 which bites into the rubber member 31 and prevents the plastic member 32 moving rearwardly with respect to the rubber member 31.

Whilst the member 12 described above is of plastic material, it could be of any material which is less compliant than rubber, e.g. metal and GRP.

Whilst the seal 10 described above is described in use in a method of joining two pipes in a branch connection, the seal 10 is of general utility and could, for instance, be used in an opening at an end of a pipe. The seal could be made to any size to suit a particular application. The seal could be used in joining a pipe to a manhole.

Whilst the illustrated seal 10 described above is adopted to join a smooth walled branch pipe to a host pipe, it is envisaged that the two ribs 15 and 16 could be easily modified to engage a rough walled pipe, such as a concrete pipe, or a ribbed pipe.

The seal of the invention can be used to sealingly locate a pipe in an aperture in a container.

Whilst the seal 10 described above is a two part seal which consists of two separate members arranged in such a way that neither of the members needs to be bonded to the other (although in practical circumstances they may be bonded for added security), seals according to the invention could also be provided by bonding two members together as can be seen in figures 4 and 5 In figure 4 a seal 40 comprises a first compliant member 41 bonded to a second less compliant member 42.

An inwardly facing rib 42 of the first compliant member is wholly supported by a portion 44 of the second compliant member 42 which is sandwiched as an intermediate layer between a radially outermost surface and a radially innermost surface of the compliant member 41 and which is cylindrical in nature. The portion 44 of the second compliant member also provides support for a tapering outer surface 45 of the compliant member 41 which defines with a flange 46 a slot 47 for engaging a wall of a container or conduit. The first compliant member 41 only extends over the portion 44 of the second compliant member 42 and does not extend over any other part of the second compliant member 42.

In figure 5 a seal 50 is shown which comprises a first compliant member 51 bonded to a second less compliant member 52. The second compliant member 52 has a triangular cross-section annular portion 53 at one end which is sandwiched between as an intermediate layer between a radially inner layer and a radially outer layer of the first compliant member 51, the portion 53 providing a firm support for an inwardly facing rib 54 of the first compliant member 51 which in use engages a branch pipe.

The first compliant member 51 also has a second inwardly facing rib 55 for engaging a branch pipe, which is not supported by the second compliant member 52, and a tapering surface 56 which defines with a flange 57 a slot 58 for engaging a wall of a conduit or a container.

Whilst in the method described above the two part seal 10 is used (and is indeed advantageously used), it is envisaged that many other types of compliant seal (eg one part one material seals) could be used in the method, eg the seals illustrated in figures 6 and 7. In figure 6 the seal 60 comprises a first compliant member 61 bonded to a second less compliant member 62. The second less compliant member still provides a stop to prevent a branch pipe being inserted too far into a host pipe, but no longer provides firm support for two inwardly facing ribs 63 and 64 of the first compliant member 61 which engage in use a branch pipe or support for a tapering exterior surface 65 of the first compliant member 61 which defines with a flange 66 a slot 67 for engaging a host pipe.

The seal 70 in Figure 1 is made of one compliant material only and no second member is provided for supporting two inwardly facing ribs 71 and 72 for engaging a host pipe or a tapering surface 73 which defines with a flange 74 a slot for engaging a host pipe.

Whilst the rib 15 and rib 16 advantageously have the particular cross-sections in the embodiments described above, it is envisaged that they could have several different cross-sections and still be effective.

Whilst the host pipe described above is a circular cross-section concrete pipe, the conduit could be of any other cross-section, eg polygonal, square, oval or rectangular. Indeed the method of the invention is suitable for joining a pipe to a container and the seal of the invention can be used in an aperture in the wall of a container acting between the wall and a conduit leading from the container.

The host pipe or container could be of any material, eg plastic, concrete clay, steel, iron or a composite.

Claims

1. A method of joining a first conduit to a second conduit in a branch connection comprising the steps of: creating an aperture in a wall of the first conduit, inserting compliant sealing means into the aperture, and inserting the second conduit into the aperture and compressing at least a portion of the sealing means located between the first and second conduits in order that the sealing means sealingly locates the second conduit in the aperture.

2. A method as claimed in claim 1 wherein at least a portion of the compliant sealing means is compressed on insertion of the sealing means in the aperture.

3. A method as claimed in claim 1 or claim 2 wherein at least a portion of the compliant sealing means is compressed by the insertion of the second conduit into the aperture.

4. A method as claimed in any one of the preceding claims wherein the first conduit is of a first material and the second conduit is of a second different material.

5. A method as claimed in any one of the preceding claims wherein the first conduit is a concrete host pipe and the second conduit is a clay branch pipe.

6. A method as claimed in any one of the preceding claims wherein the first conduit is a pipe of circular cross-section.

7. A method as claimed in any one of the preceding claims wherein the second conduit is a smooth-walled branch pipe and the first conduit is a rougher walled host pipe.

8. A seal for use in an aperture in a first conduit or in a container which in use acts between a surface defining the aperture and a second conduit in order to sealingly locate the second conduit in the aperture, wherein the seal comprises a first compliant part and a second less compliant part which are arranged such that a least a portion of the first compliant part is compressed between the surface defining the aperture and the second less compliant part when the seal is inserted into the aperture.

9. A seal as claimed in claim 8 wherein the first compliant part and the second less compliant part are arranged such that at least a portion of the first compliant part is compressed between the second less compliant part and the second conduit when the second conduit is inserted into the aperture.

10. A seal as claimed in claim 9 or claim 10 wherein the first compliant part is an outer part of the seal which has first engagement means for engaging the first conduit or the container to locate the seal in the aperture.

11. A seal as claimed in claim 10 wherein the first engagement means comprises a flange which in use remains outside the first conduit or the container and which provides a stop to limit insertion of the seal into the aperture and a rib which engages the inside surface of first conduit or the container and which is compressed between the first conduit or container and the second less compliant part when the seal is inserted into the aperture.

12. A seal as claimed in claim 10 or claim 11 wherein the first compliant part has second engagement means for engaging the second conduit.

13. A seal as claimed in claim 12 wherein the second engagement means is compressed between the second less compliant part of the seal and the second conduit when the seal sealingly locates the second conduit in the aperture.

14. A seal as claimed in claim 12 or claim 13 wherein the second engagement means comprises first and second spaced part ribs which both engage the second conduit when the seal sealingly locates the second conduit in the aperture, the second rib acting in use to prevent lateral loading of the second conduit from causing a leak.

15. A seal as claimed in claim 14 wherein the first rib before compression has a cross-section which is a right-angled triangle.

16. A seal as claimed in claim 14 or claim 15 wherein the second rib before compression has a crosssection which is an isosceles triangle.

17. A seal as claimed in any one of claims 8 to 16 wherein the second less compliant part of the seal has a flange which acts a stop to limit insertion of the second conduit into the aperture.

18. A seal as claimed in any one of claim 8 to 17 wherein the second less compliant part of the seal has a first portion which can abut the second conduit when the second conduit is located in the aperture and a second portion which is separated from the second conduit by a portion of the first compliant part of the seal.

19. A seal as claimed in claim 8 wherein the first compliant part of the seal is a first generally cylindrical resilient member which has a radially outwardly extending flange at one end, a radially inwardly extending flange at the other end, a radially outwardly protruding annular rib spaced apart from the radially outwardly extending flange and acting with the radially outwardly extending flange to engage the first conduit or the container to locate the seal in the aperture, a first inwardly extending rib of right-angled triangle cross-section and a second inwardly extending rib of isosceles triangle cross-section spaced apart from the first inwardly extending rib, and the second less compliant part of seal is a generally cylindrical resilient member and has a radially outermost surface which is entirely overlaid by the first resilient member, at one end an inwardly extending flange in abutment with the inwardly extending flange of the first resilient member, a first cylindrical portion with a first internal diameter and a second cylindrical portion with a second larger internal diameter which is embedded in the first resilient member.

20. A seal as claimed in claim 19 wherein the outwardly protruding annular rib of the first compliant member overlays the second less compliant member and the isosceles triangle cross-section extending rib is located radially inwardly of the second cylindrical portion of the second compliant member to be compressed between the second compliant member and the second conduit when the second conduit is inserted into the aperture.

21. A seal as claimed in any one of claims 8 to 20 wherein the first compliant part of the seal is a rubber or polyurethane member.

22. A seal as claimed in any one of claims 8 to 21 wherein the second less compliant part of the seal is a plastic member.

23. A seal as claimed in any one of claims 8 to 22 wherein the second less compliant part of the seal is a glass reinforced plastic member.

24. A seal as claimed in any one of claims 8 to 22 wherein the second less compliant part of the seal is a metal member.

25. A method of joining a first conduit to a second conduit in a branch connection comprising the steps of: creating an aperture in a wall of the first conduit, inserting a seal as claimed in any one of claims 8 to 25 into the aperture created in the wall and compressing the first compliant part of the seal between the second less compliant part of the seal and a surface defining the aperture during insertion of the seal into the aperture, whereby the seal is retained in the aperture, and inserting the second conduit into the aperture to be sealingly located by the seal in the aperture.

26. A method as claimed in claim 22 wherein the insertion of the second conduit in the seal compresses a portion of the first compliant part between the second less compliant part and the second conduit, whereby the seal sealingly locates the second conduit in the aperture.

27. A method as claimed in claim 26 wherein the first conduit is of a first material and the second conduit is of a second different material.

28. A method as claimed in claim 27 wherein the first conduit is of concrete and the second conduit is of clay.

29. A method as claimed in any one of claims 25 to 28 wherein the first conduit is a pipe of circular axial cross-section.

30. A method as claimed in any of claims 22 to 26 wherein the second conduit is a smooth walled pipe at the first conduit in a rough walled pipe.

31. A seal substantially as hereinbefore described with reference to and as shown in the accompanying drawings.