GB2041147A

GB2041147A - Renovating sewers

Info

Publication number: GB2041147A
Application number: GB8001358A
Authority: GB
Original assignee: FUSION EQUIPMENT Ltd
Current assignee: FUSION EQUIPMENT Ltd
Priority date: 1979-01-22
Filing date: 1980-01-15
Publication date: 1980-09-03
Also published as: GB2041147B

Abstract

To renovate a sewer a flexible pipe (3) is inserted into a main collector sewer (1), a hole is cut in the pipe (3) at the location of a branch pipe (2) by means of a remotely operated cutter, Figs. 1, 2 not shown, introduced through branch pipes (2) or (3), and a rubber liner sleeve (9) is inserted to seal around the hole cut in the flexible pipe (3) and against the inner wall of the branch pipe (2). The liner sleeve (9) has a flange (12) held in sealing contact with pipe (3) by a rib (13), and is internally tapered at its outer end. The liner is drawn into position by a flexible line attached to the liner by a releasable gripping device. In a modification, Figs. 7-9 (not shown) wherein the branch pipe (2) is at an acute angle to the sewer pipe (3), the flanged liner sleeve (9) is replaced by a flared-end liner (20) which is sawn off flush after insertion. Grout may be inserted between pipes (3) & (1). <IMAGE>

Description

SPECIFICATION Improvements in or relating to the renovation of sewers This invention is concerned with the renovation of sewers and, more particularly relates to a method of renovating sewers by insertion of flexible pipe and to apparatus for use in carrying out the method.

Infiltration of rainwater into foul sewage systems through faults in the walls of old sewer pipes which have deteriorated with age having been buried underground for several years is a serious problem because of the extra load which is put on sewage treatment plants as a result of their having to handle additionally the infiltrated rainwater.

Conventional gravity sewer networks consist of a large diameter collector sewer normally laid deep undergound in a roadway and 'lateral' pipes of smaller diameter which branch off from the collector sewer and serve to feed sewage from respective dwellings into the collector sewer.

It has been propsed previously to renovate collector sewers by inserting flexible polyethylene pipe and this method has proved fairly successful, especially where the collector sewers are laid in long, straight uninterrupted lengths and access is available through manholes. Once the polyethylene pipe has been installed in the collector sewer it is necessary to connect all the 'laterals' to it, which is not so straight forward. It is common for laterals to be connected every few feet along a collector sewer and it is very uneconomical to dig up each one in order to complete the necessary connection. Furthermore, the insertion of small diameter polyethylene pipe into the laterals is often impossible making the connection between the collector sewer and laterals more difficult since it is essential that a leak tight seal should exist between the laterals and collector sewer.

The present invention aims at providing a solution to the above problem and accordingly provides a method of renovating a sewer system including a collector sewer and lateral sewer pipes branching from the collector sewer, comprising the steps of inserting a flexible pipe into the collector sewer, cutting a hole in the flexible pipe at the connection between the collector sewer and a lateral sewer pipe, and inserting a flexible tubular liner to seal around the hole cut in the flexible pipe and extend along the lateral sewer pipe.

Using the above method an effectively sealed connection can be made between a collector sewer and a lateral and all the apparatus can be carried out remotely.

The tubular liner may be adapted to seal against the interior surface of the lateral sewer pipe, in which case it may extend only a short distance along this pipe. It is also possible for the liner to be inserted the full length of the branch pipe and be connected to an inspection pit wall, for example by mortar or any other method.

The invention also includes a sewage system renovated by the method and a tubular liner for use in carrying out the method. In one preferred form the liner is made of rubber and comprises a radially outwardly directed flange at one end for sealing against the inner surface of the first pipe around the hole, a peripheral rib extending around the liner tube at a distance from the flange approximately equal to the wall thickness of the flexible pipe for holding the liner in position on the flexible pipe.

The above liner is ideal for relining lateral connections, to seal the branch sewer pipe to the flexible pipe installed in the collector sewer, when the lateral is at 90 to the collector. However, many connections are made at an angle of 45 and in most cases the actual orientation of a lateral to the collector sewer can only be determined by excavation. A suitable form of liner for sealing connections of 45 or 90 consists of a length of flexible tubing, e.g. rubber, which is flared at one end for sealing around the hole cut in the flexible pipe when the liner is drawn into the lateral. Any part of the liner protruding into the interior of the flexible pipe can be removed by means of a cutter passed through the flexible pipe, so that it does not constitute an obstruction.

If a liner is to extend only a short distance along a branch pipe it is preferably provided with an internal taper at the end opposite the flange or flaring to provide a smooth transition from the inner diameter of the liner to that of the branch pipe.

A more complete understanding of the invention will be had from the following detailed description, given by way of example, with reference to the accompanying drawings, in which: Figure 1 is a vertical cross-section through a sewer system; Figure 2 is a longitudinal cross-section through part of a sewer system; Figure 3 shows a liner in axial cross-section; Figure 4 shows the liner attached to a nose cone ready for installation; Figure 5 shows the liner being located in position in a longitudinal cross-section; Figure 6 is a view similar to Fig. 5 on an enlarged scale and showing the liner in pos.

tion; Figure 7 is a longitudinal cross-section through a sewer system in the course of renovation by the method of the invention; Figure 8 is a section through the end of the tubular liner shown in Fig. 7; and Figure 9 is a similar view to Fig. 7 showing a rotary cutter trimming the inner end of the liner.

Referring to the drawings, and in particular to Fig. 1, there is shown a sewage system in the process of renovation and including a collector sewer 1 from which branch off lateral pipes, such as that designated 2. A first step in the renovation is to insert a flexible polyethylene liner pipe 3 into the collector sewer 1 between conveniently located manholes, for example manholes A and B B seen in Fig. 5. The next step is to connect the laterals 2 to the collector sewer which is achieved by cutting a circular coupon out of the wall of the flexible pipe at the location where the lateral 2 joins the old sewer 1. The cutting can, for example, be performed by means of hole cutter 4 carried on a flexible drive 5 and inserted into the lateral through an access point at ground level.Alternatively, the hole in the flexible pipe 3 may be produced by a cutting device 6 (Fig. 2) inserted into the flexible pipe 3 from a convenient manhole A. The cutting device is remotely controlled to take up the correct position at the joint between the lateral 2 and the collector sewer 1 by introducing a signal transmitter 7 into the lateral 2 and mounting a receiver 8 on the cutting device 6. When the coupon has been cut out the cutting equipment 4, 5 or 6, 7, 8 is removed.

The next step is to insert a wire rope into the lateral 2 from the access point at ground level and to feed it through the lateral until it enters the polyethylene pipe 3. A second wire rope passed through pipe 3 between the manholes A and B is used to pick up the end of the rope inserted through the lateral and to draw it through to one of the manholes. The "picking up" can be achieved by providing a loop at the end of the first rope and hooks on the second. Alternatively, instead of using the second rope the first rope could be simply fed into the lateral until its end appeared at either of the manholes A, B but it would not be possible to predetermine at which manhole the rope end would appear. At the manhole a tubular rubber liner 9 which is to be used to connect the polyethylene pipe 3 to the lateral 2 is connected to the end of the wire rope extending through the lateral 2.

The liner 9 is shown in Fig. 3 and consists of a moulded rubber end part 10 which is cemented or otherwise connected (e.g. by vulcanizing) to a rubber pipe length 11 selected to suit the particular lateral to which it is to be fitted. The end part 10 includes a radially outwardly directed flange 12 and a peripheral rib 13 spaced from the flange by a distance substantially equal to the wall thickness of the polyethylene pipe 3 for retaining the liner on the pipe 3 with the flange 12 lying and sealing against the inner surface of the pipe, as will become clear from the follow- ing description. At its free end the rubber pipe 11 has an internal taper 14 to provide a smooth transition from the internal diameter of the liner 9 to that of the lateral 2.

The liner 9 is attached to the end of the wire rope, as seen in Fig. 4, by a nose cone 15 having an internal release mechanism which is remotely actuable to release the nose cone from the liner. If the liner being inserted is to extend the full length of the lateral, the release mechanism of course, need not be remotely actuable.

The liner 9 is drawn through the pipe 3 from the manhole by means of the wire rope 16 and nose cone 15 and is then pulled through the hole cut in the pipe 3 into the lateral 2 (Fig. 5) until the rib 13 of the liner has passed through the hole and the flange 12 lies against the internal surface of pipe 3 around the hole. The release mechanism of the nose cone 15 is actuated to let go the liner 9 and the wire rope 16 and nose cone are withdrawn completely from the lateral 2.

The end of the liner expands and seals against the internal wall of the lateral.

As may be seen in Fig. 6, the liner 9 when fitted in position is securely attached to the polyethylene pipe 3 by the flange 12 and rib 13 and provides a sealed connection between the pipe 3 and lateral 2. In addition the method of installation is reasonably simple and effected remotely.

The method and liner described above with reference to Figs. 1 to 6 are ideal when the lateral pipes join the collector sewer at 90 . In many instances, however, the connections are at an angle of 45 , as shown in Fig. 7. (In Figs. 7 to 9 the same reference numerals as in the earlier Figs. are used to designate corresponding parts.) The flexible pipe 3 is introduced into the collector sewer 1 and a hole is cut through the wall of the pipe 3 at the juncture between the lateral 2 and collector 1, in the same manner as described with reference to Figs. 1 and 2.The liner 20 consists of a length of rubber tubing which is flared at its inner end so that the tubing engages and seals around the edge of the hole cut in pipe 3 when the liner 20 is drawn into the lateral 2 from the interior of pipe 3, for example by means of a flexible line as in Fig. 5. In order to complete the seal and anchor the liner 20 it may be necessary to inject grouting compound 21 into the annular space between the old sewer 1, 2 and the liner. The grouting material may, for example, be introduced from access points at manholes where the liner emerges. So that the liner 21 does not collapse during the grouting process it may be necessary to support it internally, such as by means of an inflatable bag (not shown). The bag could be inserted before or after installation of the liner 20 and would be deflated and removed when the grout has hardened. All these operations can be conveniently performed remotely from the lateral and collector connection. As a final step the part of the liner protruding into the pipe 3 can be trimmed off by means of a rotary cutter 22 (Fig. 9) so as not to constitute an obstruction to material flowing along the pipe 3.

Because the liner 20 has a flared end it can be used with equal effect where the lateral is at 90' or 45 to the collector sewer. It therefore has the advantage that it is not necessary to determine the angle at which the lateral 2 intersects the collector sewer 1 as a preliminary step prior to installation.

Claims

1. A method of renovating a sewer system including a collector sewer and lateral sewer pipes branching from the collector sewer, comprising the steps of inserting a flexible pipe into the collector sewer, cutting a hole in the flexible pipe at the connection between the collector sewer and a lateral sewer pipe, and inserting a flexible tubular iner to seal around the hole cut in the flexible pipe and extend along the lateral sewer pipe.

2. A method according to claim 1, wherein the steps of cutting the hole in the flexible pipe and inserting the tubular lining are performed remotely from the installation site of the liner.

3. A method according to claim 2, wherein the hole is cut in the flexible pipe by a a cutter device passed through the lateral sewer pipe from an access point at ground level.

4. A method according to claim 2, wherein the hole is cut in the flexible pipe by a a cutter device introduced along the flexible pipe, and signal producing or sensing means passed through the lateral sewer pipe serves to locate the cutter correctly for cutting the hole.

5. A method according to claim 2, 3 or 4, wherein the liner is drawn into position from within the flexible pipe by a flexible element passed through the lateral sewer pipe and through the hole cut in the flexible pipe.

6. A method according to claim 5, wherein the flexible element is connected to the liner by releaseable gripping means.

7. A method according to any one of claims 1 to 6, wherein the liner has a peripheral flange at its inner end for sealing contact with the inner wall of the flexible pipe, and projection means spaced from the flange by a distance substantially equal to the wall thickness of the flexible pipe for engaging the outer wall of the flexible pipe to hold the liner firmly in position.

8. A method according to any one of claims 1 to 7, wherein the liner has an internal taper at its outer end to provide a smooth transition from the inner diameter of the liner to that of the lateral sewer pipe.

9. A method according to any one of claims 1 to 8, wherein the liner is made of rubber.

10. A method of renovating a sewer system substantially as herein described with reference to Figs. 1 to 6 of the accompanying drawings.

11. A sewer system when renovated by the method of any one of the preceding claims.

12. A tubular liner for use in renovating sewer systems by the method of claim 1, comprising a tube of resiliently flexible material having an external flange adjacent one end, and an external protrusion spaced at a small distance from the flange and axially inwardly thereof, the tube having a smooth internal bore whose diameter increases towards the end opposite said one end to provide a smooth transition from the interior of the tube to the inner wall of a sewer pipe in which said opposite end is installed.

13. A tubular liner according to claim 12, wherein said protrusion is a peripheral rib.

14. A tubular liner substantially as herein described with reference to Fig. 3 of the accompanying drawings.

15. A method according to any one of claims 1 to 6 wherein the liner consists of a length of flexible tubing which is flared at one end thereof which seals against the flexible pipe.

16. A method according to claim 15, wherein grouting material is introduced into the space between the old sewer and flexible pipe.

17. A method according to claim 16, wherein the liner is supported internally against collapsing during introduction of the grouting material.

18. A method according to claim 17, wherein the liner is supported by an inflated bag which is deflated and removed when the grouting material has hardened.

19. A method according to any one of claims 15 to 18, wherein a part of the liner protruding into the interior of the flexible pipe is trimmed off.

20. A method of renovating a sewer system substantially as herein described with reference to Figs. 7 to 9 of the accompanying drawings.