GB2197044A

GB2197044A - Branch coupling-lined pipe

Info

Publication number: GB2197044A
Application number: GB08623679A
Authority: GB
Inventors: Raymond Weaver
Original assignee: Subterra Ltd
Current assignee: Subterra Ltd
Priority date: 1986-10-02
Filing date: 1986-10-02
Publication date: 1988-05-11
Anticipated expiration: 2006-10-02
Also published as: GB8623679D0; GB2197044B

Abstract

An end portion of a second pipe or pipe connector is joined to the circumferential surface of a first pipe 1 having an outer casing 2 and a polyolefine lining 3 by drilling a first aperture 5 in the outer casing of such diameter that it is formed without the drill impinging on the lining. A probe 11 is inserted through the first aperture 5 to ensure a clearance between the lining 3 and its casing 2 such as to enable the drilling of a second aperture 7 in the casing without impinging on the lining. The second aperture 7 is large enough to accommodate one end portion of the second pipe or pipe connector, which is secured to the lining. Within the second pipe or pipe connector, an opening is formed in the lining 3 to allow communication between the interior of the first pipe 1 and that of the second pipe or pipe connector. <IMAGE>

Description

SPECIFICATION Improvements in and relating to joining pipes The invention relates to joining pipes, and especially to joining to the circumferential surface of a first pipe an end portion of a second pipe or an end portion of a pipe connector for a second pipe, the first pipe having an outer casing and a polyolefine pipe lining.

It has previously been proposed to line pipework, for example, underground main sewer pipes, water mains or gas mains, with polyolefine pipes. Lining may be carried out in the manner known as "slip lining" in which polyolefine pipes having an external diameter slightly smaller than the internal diameter of the existing pipework are inserted into the pipework, and a small clearance remains between the lining and the pipework, in use.

Alternatively, polyolefine pipes of external diameter greater than the internal diameter of the pipework can be roll reduced so that their external diameter is less than the internal diameter of the pipework. The polyolefine pipes are fed into the pipework and are then caused to expand into engagement with the walls of the pipework. Such a lining process is disclosed in United Kingdom Patent Specification No. 2 084 686.

Problems arise when it is required to join to the lined pipework secondary pipes, for example, pipes known as service pipes, which serve to connect domestic or commercial premises to the mains, or branch pipes to serve as branches of the mains. It is highly desirable for this operation to be performed without shutting down the mains, the interior of which, in use, will generally be at a considerably higher pressure than that on the exterior.

To join a secondary pipe, it is necessary to cut an aperture in the original pipework, now forming an outer casing, in order to secure to the polyolefine lining an end portion of the secondary pipe itself or an end portion of a pipe connector, to which the secondary pipe is, in turn, secured. Because of the curvature of the pipework, a drill arranged to cut a circular opening in the casing of the pipework large enough to accomodate one end of the secondary pipe or pipe connector will generally also cut through the lining rupturing the mains, so that such a process cannot be used without shutting down the mains. Accordingly, it has been proposed to use a wheel cutter, which cuts in straight lines, to remove a portion of the outer casing, so that a secondary pipe can then be joined to the lining.

The invention provides a method of joining to the circumferential surface of a first pipe having an outer casing and a polyolefine lining an end portion of a second pipe or an end portion of a pipe connector for a second pipe, which comprises drilling a first aperture in the outer casing of the first pipe of such diameter that the first aperture is formed without the drill impinging on the lining, inserting a probe through the first aperture to ensure a clearance between the lining and its casing in the region of the first aperture such as to enable the drilling of a second aperture in the outer casing without impinging on the lining, the second aperture being large enough to accomodate one end portion of the second pipe or pipe connector, drilling the second aperture, securing the end portion of the second pipe or pipe connector to the lining, and, within the second pipe or pipe connector, forming an opening in the lining to allow communication between the interior of the first pipe and the interior of the second pipe or pipe connector.

With the method of the invention, the first aperture or pilot aperture has only to be of a size sufficient for the probe to be inserted, and therefore can be of such a small diameter relative to the diameter of the first pipe that the curvature of the pipe does not create a problem and the aperture can be drilled without the drill impinging on the lining, that is to say, without the drill so cutting into the lining as to materially weaken the lining or otherwise materially impair its performance. The probe, inserted through the pilot aperture, can ensure the necessary clearance between the lining and the casing for the drilling of the second larger aperture by pushing the lining away from the casing where necessary.Accordingly, it is possible for secondary service or branch pipes to be joined to a main pipeline, either directly to the lining or to pipe connectors secured to the lining, by the use of a drill without shutting down the main pipeline. This has advantages over the use of a wheel cutter as previously proposed not only in terms of speed and convenience but also because the aperture in the casing for the second pipe or pipe connector can be substantially circular and of only slightly greater diameter than the diameter of the end portion of the pipe or pipe connector to be joined, so that loss in structural strength of the first pipe caused by the joining of the second pipe or pipe connector can be kept as low as possible.

Advantageously, the second aperture is formed by means of a drill on which the probe is coaxially mounted, the probe being arranged to project beyond the cutting edge of the drill. The probe can then ensure that the lining is maintained in a position away from the casing while the second aperture is being formed. With this arrangement, the probe is advantageously mounted on the drill so that the cutting edge of the drill and the probe, or at least that end portion of the probe that projects beyond the cutting edge of the drill, are capable of relative rotation.

The probe or the said end portion of the probe can then remain stationary while the drill is forming the second aperture. Such an arrangement is desirable since it avoids the possibility of the probe rubbing against or abrading the lining during the cutting of the second aperture and damaging it, although, since that portion of the lining is later removed when the opening is cut within the second pipe, it is not absolutely essential.

The distance by which the probe projects beyond the cutting edge of the drill is advantageously within the range of from 0.10 to 0.75 of the diameter of the cutting edge of the drill.

In addition to the lining of the first pipe, the second pipe or pipe connector for the second pipe may also be made of a polyolefine, for example, polyethylene, but the expression "polyolefine" is used in this specification to include substituted polyolefines, for example, polyvinyl chloride.

The invention also provides a drill and a probe for forming a second aperture in accordance with the method of the invention wherein the probe is mounted on the drill so as to be coaxial with the drill and projects beyond the cutting edge of the drill.

A method of joining to the circumferential surface of a first pipe an end portion of a second pipe or pipe connector for a second pipe in accordance with the invention and a drill and a probe for carrying out the method of the invention will now be described by way of example with reference to the accompanying drawings. in which: Fig. 1 is a cross-section through part of a pipe showing diagrammatically a first step in the method of the invention; Fig. 2 is a cross-section through a part of a pipe showing diagrammatically a second step in the method of the invention; Fig. 3 is a cross-section through a pipe showing diagrammatically a third step in the method of the invention; and Fig. 4 is a diagrammatic longitudinal section through part of the pipe shown in Fig. 3; Fig. 5 is a longitudinal section through a part of the pipe showing showing a fourth step in the method of the invention; and Fig. 6 is a diagrammatic axial section through a drill and a probe for carrying out the third step of the method of the invention; Referring to the accompanying drawings, and initially to Fig. 1, a first pipe, indicated generally by the reference numeral 1, which is, for example, a main sewer pipe, water main, gas main, or a pipe for carrying oil or slurry, has an outer casing 2 made of, for example, cast iron, and a pipe lining 3 made of polyolefine, for example, polyethylene.A drill (only a part of which is shown diagrammatically in Fig. 1) having a cup drill or tank cutter 4 with a cutting edge 4a of small diameter relative to the diameter of the first pipe 1 is used to drill a first pilot aperture 5 (see Fig. 2! in the outer casing 2 of the first pipe 1. The diameter of the tank cutter 4 is sufficiently small relative to the diameter of the pipe 1 that the pilot aperture 5 can be drilled without the cutting edge 4a of the drill impinging on the pipe lining 3, that is to say, without the drill so cutting into the pipe lining 3 as to materially weaken the lining or otherwise materially impair its performance, although it may merely contact the lining.

A drill, indicated generally by the reference numeral 6, (only a part of which is shown) is used to cut a second aperture 7 in the outer casing 2 of the first pipe 1 as can be seen in Figs. 3 and 4. The drill 6 has a mandrel (not shown) on which is mounted a cup drill or tank cutter 8 with a cutting edge 8a of a diameter slightly greater than the external diameter of a saddle or flange 8 at one end of a pipe connector 10 (see Fig. 5) for a second pipe to be joined to the circumferential surface of the first pipe 1 to form, for example, a service pipe for connecting domestic or commercial premises to the mains, or a branch of the mains.A probe, indicated generally by the reference numeral 11, is mounted coaxially on the drill 6 and comprises a body portion 12 secured to the drill mandrel and a nose portion 13 separated from the body portion 12 by a thrust race 14 so that the nose portion and the body portion are capable of relative rotation. The nose portion 13 projects beyond the cutting edge 8a of the drill 6 by a distance within the range of from 0.10 to 0.75 of the diameter of the cutting edge. The projecting end surface of the nose portion 13 is rounded to provide a deflecting surface 13a.

In the method of the invention, as can be seen from Figs. 3 and 4, the nose portion 13 of the probe 11 is first inserted through the pilot aperture 5 until the deflecting surface 13a bears against the lining 3. The probe 11 is then moved further through the pilot aperture 5 so that the nose portion 13 pushes the lining 3 away from the outer casing 2 of the pipe 1. The probe 11 maintains the lining in a deflected state while the drill 6 is operated and the cutting edge 8a cuts the second aperture 7 in the outer casing of the pipe 1. The probe 11 extends far enough beyond the cutting edge 8a of the drill 6 that the lining 3 is held clear of the cutting edge 8a as the second aperture is formed without the risk of the cutting edge impinging on the lining, that is to say, without the drill so cutting into the pipe lining 3 as to materially weaken the liner or otherwise materially impair its performance.

Because of the thrust race 14, the nose portion 13 of the probe 11 can remain stationary while the body portion 12 of the probe and the cutting edge 8a of the drill rotate, thus avoiding damage which might be caused if the nose portion 13 rotated with the cutting edge 8a and rubbed against or abraded the lining.

After the second aperture 7 is formed, the drill 6 with the probe 11 are removed, whereupon the lining 3 reverts to its original shape. The flange 9 at one end of the pipe connector 10 is then secured to the lining 3 in a suitable manner. Lengths of pipe can be secured to the pipe connector 10, as required, to form a service or branch pipe. Finally, a cutter (not shown) within the pipe connector 10 can be screwed down inside the connector to form an opening in the lining 3 and allow communication between the interior of the first pipe 1 and the interior of the pipe connector 10 and the service or branch pipe connected thereto.

The pipe connector 10 and its flange 9 may be made of polyolefine, for example, polyethylene, in which case the flange 9 may be secured to the lining 3 by fusion.

Instead of securing the flange 8 of the pipe connector 10 to the lining 3, a length of pipe having a flange similar to the flange 9 may be secured directly to the lining in a similar manner.

Fig. 6 shows another form of drill, indicated generally by the reference numeral 15, suitable for carrying out the reference to Figs. 3 and 4. The drill 15 has a mandrel 16 on which is mounted a cup drill or tank cutter 17 with a cutting edge 17a of a diameter slightly greater than the external diameter of a flange at one end of a pipe connector or pipe to be joined to the circumferential surface of the first pipe 1. A probe, indicated generally by the reference numeral 18, is mounted coaxially on the drill 15 and comprises a body portion 19 secured to the drill mandrel 16 by means of a retaining nut 20 (which also serves to secure the tank cutter 17 to the mandrel) and a nose portion 21 separated from the body portion 19 by a thrust race 22 and secured to the body portion by a retaining screw 23 so that the nose portion and the body portion are capable of relative rotation. The nose portion 21 projects beyond the cutting edge 17a of the drill 15 by a distance within the range of from 0.10 to 0.75 of the diameter of the cutting edge. The projecting end surface of the nose portion 21 is rounded to provide a deflecting surface 21a.

The drill 15 and the probe 18 are used in the same manner as the drill 6 and the probe 11.

Claims

1. A method of joining to the circumferential surface of a first pipe having an outer casing and a polyolefine lining an end portion of a second pipe or an end portion of a pipe connector for a second pipe, which comprises drilling a first aperture in the outer casing of the first pipe of such diameter that the first aperture is formed without the drill impinging on the lining, inserting a probe through the first aperture to ensure a clearance between the lining and its casing in the region of the first aperture such as to enable the drilling of a second aperture in the outer casing without impinging on the lining, the second aperture being large enough to accomodate one end portion of the second pipe or pipe connector, drilling the second aperture, securing the end portion of the second pipe or pipe connector to the lining, and, within the second pipe or pipe connector, forming an opening in the lining to allow communication between the interior of the first pipe and the interior of the second pipe or pipe connector.

2. A method as claimed in claim 1, wherein the second aperture is formed by means of a drill on which the probe is coaxially mounted, the probe being arranged to project beyond the cutting edge of the drill.

3. A method as claimed in claim 2, wherein the second aperture is formed by means of a drill on which the probe is so mounted that the cutting edge of the drill and the probe, or at least that end portion of the probe that projects beyond the cutting edge of the drill, are capable of relative rotation.

4. A method as claimed in claim 2 or claim 3, wherein the distance by which the probe projects beyond the cutting edge of the drill is within the range of from 0.10 to 0.75 of the diameter of the cutting edge of the drill.

5. A method as claimed in any one of claims 1 to 4, wherein the second pipe or pipe connector for the second pipe are made of a polyolefine.

6. A method as claimed in any one of claims 1 to 5, wherein the polyolefine is polyethylene.

7. A drill and a probe for forming a second aperture as claimed in any one of claims 1 to 6, wherein the probe is mounted on the drill so as to be coaxial with the drill and projects beyond the cutting edge of the drill.

8. A drill and a probe as claimed in claim 7, wherein the probe is so mounted on the drill that the cutting edge of the drill and the probe, or at least that end portion of the probe that projects beyond the cutting edge of the drill, are capable of relative rotation.

9. A drill and a probe as claimed in claim 7 or claim 8, wherein the distance by which the probe projects beyond the cutting edge of the drill is within the range of from 0.20 to 0.75 of the diameter of the cutting edge of the drill.

10. A method of joining to the circumferential surface of a first pipe an end portion of a second pipe or pipe connector for a second pipe substantially as hereinbefore described with reference to the accompanying drawings.

11. A drill and a probe as claimed in any one of claims 7 to 9 and substantially as hereinbefore described with reference to, and as shown in, either Figs. 3 and 4, or Fig. 6, of the accompanying drawings.