GB2213229A

GB2213229A - Method and apparatus for pipe replacement

Info

Publication number: GB2213229A
Application number: GB8817871A
Authority: GB
Inventors: Masataka Fukami; Yoshitaka Niki; Kenji Kondo
Original assignee: Kurimoto Ltd
Current assignee: Kurimoto Ltd
Priority date: 1987-12-07
Filing date: 1988-07-27
Publication date: 1989-08-09
Anticipated expiration: 2008-07-27
Also published as: JPH01150087A; DE3835900C2; DE3835900A1; CA1326600C; GB2213229B; GB8817871D0

Description

-i- 4 I- Description of Invention "Method and apparatus for pipe

replacemenC J d- THIS INVENTION relates to a method and apparatus for replacing an ex. isting old pipe, such as a water service pipe, gas pipe or the like with a new pipe and, in particular, to a method and apparatus for replacing an old pipe with a new one without digging up the ground.

When an old buried pipe, in particular a cast iron pipe, has deteriorated with age or when it is necessary to replace the old pipe with a new one due to new requirements, it is desirable to be able to replace the old pipe with a new one without digging up the ground, because great labour and cost is involved in excavating the old pipe and because such digging work unavoidably obstructs traffic or affects means of transport and communication.

According to a known method of pipe replacement called "pipe- in-pipe", a new pipe is simply inserted into the old one under the ground. However, this inevitably means that the internal diameter of the new pipe must be smaller than that. of the old pipe, resulting in a reduction in the capacity for transporting gas or water.

An attempt has already been made to overcome the above discussed drawback of the "pipe-in-pipe" method, as disclosed in U.K. Patent GB2152624B "Pipe Replacement System", GB 2124325B and GB 2092701B "Mains Insertion", and which is illustrated in detail in Figures 4 to 6 of the accompanying drawings.

Figure 7 illustrates a manner of actual use of this prior apparatus, which is taken from a catalogue explaining the practical use of the apparatus on a commercial basis, and Figure 8 illustrates a method based on an improvement of the method of Figure 7.

The aforesaid prior art discloses a method and an apparatus for pipe replacement in which a new pipe is attached to the rear end of a bursting mole having a cylindrical body with an external diameter which is larger than that of the old pipe to be replaced. The bursting mole and the new pipe move forward together, and a front end or head of the bursting mole intrudes into the old pipe and progressively bursts the old pipe to form an enlarged space to receive the new pipe, so that the old pipe is replaced with the new one.

An embodiment of this prior art apparatus will now be more specifically described with reference to Figures

4 to 6.

The bursting mole 8a comprises a front section which intrudes into the old pipe 11a and bursts the wall thereof, and a rear section which is connected to the new pipe la to tow the new pipe behind the bursting mole.

The front section of the mole has a head 14a with cutting blades 13a thereon, and a front end of the head is drawn forward by a winch (not illustrated) by way of a traction cable 10a which is passed through the old pipe.

Cutting edges 15a are provided on the blades 13a, and at least one blade can be pivoted outwardly from the bursting mole in order to cut the wall of the old pipe.

In Figure 5, a fluid pressure hose extending forwardly through the old pipe delivers a pressure fluid a to actuate a piston 16a provided in the head of the bursting mole. The- piston, in turn, acts on blade 13a to pivot it outwardly thereby to cut the wall to form an enlarged space for the new pipe following behind the mole 8a.

Forward movement of the bursting mole together with the attached new pipe is performed by an air hammer 17a disposed in a hollow section of the cylindrical body of the bursting mole as illustrated in Figure 6. The piston in the air hammer slides back and forth in response to pressurized air delivered through an air hose attached to the rear end, and additionally by winching through the cable attached to the front end of the bursting mole. Additionally, a hydraulic jacking device may be provided to apply further pressure to the rear end of the new pipe as disclosed by the Applicant in Japanese Patent Application No. 61-159184.

In practice, an air hose for supplying air to the hammer 17a and incorporated inside the head of the mole, is joined to the rear of the mole by suitable means. An oil feed pipe for supplying oil under pressure to the head for rotating the blades 13a may also be joined to the rear of the mole 8a.

When a new pipe section is joined to the pipe sections behind the bursting mole, the hoses have to be inserted through the pipe section as typically illustrated in Figure 7.

In the aforementioned conventional method, however, a large working space is required in a rear portion of the starting pit. The pipe line is usually laid under a road, and it is an obstacle to traffic to secure such a large working space. Moreover, in the method illustrated in Figure 7, it is necessary to move a compressor following each forward movement of the bursting mole. In order to continue the work without moving the compressor, it would be necessary to connect a longer air hose extending at least 1.5 times the length from the starting pit to the destination pit, which results in a lowering of the air supply efficiency.

It is indeed possible to reduce the working space by forming a pipe line by joining specific lengths of new pipe together sequentially according to the forward movement of the mole as illustrated in Figure 8. However, in such an arrangement, the air supply to the mole during the replacment work is frequently interrupted as new pipe sections are added and the air hoses are extended (detached and rejoined). This is a lengthy process and considerably lowers the efficiency of the process. Moreover, as the air hose inserted through the new pipe has many couplings, the air supply efficiency is also lowered there is a possibility of damage to the internal surface of the new pipe and the cost of replacing the pipe is high due to the use of many expensive couplings.

The present invention aims to overcome or at least mitigate the above-discussed problems and to provide a method of replacing an old buried pipe with a new pipe in which the required working space is reduced and the replacement is carried out without interruption.

Accordingly, in one aspect, the invention provides a method of replacing an old buried pipe with a new pipe comprising a plurality of pipe sections, which method comprises attaching successive new pipe sections to a bursting mole having a cylindrical body whose external diameter is larger than the existing old pipe, and moving the bursting mole forward so that a head of the bursting mole intrudes into the old pipe and bursts it to provide an enlarged space for the new pipe following the bursting mole, which method furtherAncludes supplying power to a driving means carried by the bursting mole through a power line from a power source and temporarily detaching a longitudinal portion of each successive pipe section in order to introduce the power line into the pipe sections without disconnecting the line from the bursting mole.

In another aspect, the invention provides apparatus for replacing an old buried pipe with a new pipe comprising a plurality of pipe sections, which apparatus comprises, a bursting mole having a cylindrical body with an external diameter which is larger than the existing old pipe, means for attaching successive pipe sections to the bursting mole, a power source for. supplying power through a power line to a driving means carried by the bursting mole to move the bursting mole forward so that a head of the mole intrudes.into the old pipe and bursts it, and means for attaching successive pipe sections behind bursting mole wherein each pipe section is adapted to be coupled to a preceding pipe section as the mole advances and is provided with a detachable section defining a longitudinal detachable portion extending the length of the pipe section which can be temporarily detached from the pipe section in order to introduce the power line into the pipe section without disconnecting the power line from the bursting mole.

In order that the invention may be more, readily understood, embodiments thereof will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1A is a diagrammatic side view of a pipe section having a detachable portion for use in a method embodying the present invention; Figure 1B is a diagrammatic end view of the pipe section of Figure 1 with the detachable portion disconnected; Figure 1C is an enlarged fragmentary view of the connection between the detachable portion of the pipe section of Figure 1; Figure 2 is an enlarged view of the pipe section and detachable portion shown in Figure 1C, with a resilient sealing member inserted between the pipe section and the detachable portion; Figure 3A is a diagrammatic sectional view illustrating a method embodying the present invention; Figure 3B (a), (b), (c) and (d) are sectional views Of sequential steps carried out in the method of Figure 3A; -20 Figure 3C is a further diagrammatic sectional view illustrating the method embodying the present invention; Figures 4-6 are diagrammatic sectional views illustrating apparatus used in a prior art pipe replacing method;

Figure 7 is a diagrammatic sectional view illustrating a prior art pipe replacement method embodying the apparatus of Figures 4 to 6; and Figure 8 is a diagrammatic sectional view illustrating a further prior art pipe replacement method.

Referring first to Figure 3A, in order to replace an old buried pipe 1 with a new pipe 2, a bursting mole 3 is positioned at one end of the old pipe line. To this I- 4 end, a starting pit 4 is dug in the ground over a length sufficient to expose one end of the old pipe line to be replaced and to accommodate related equipment and tools.

One end of a traction cable 5 is passed through the old pipe 1 and is attached to a front end of the bursting mole 3. The cable 5 is attached at its other end to a winch (not shown) which pulls the bursting mole into the old pipe to burst it and replace it with the new pipe 2 following behind the mole 3. Since the external diameter of the cylindrical section of the bursting mole is larger than that of the old pipe, a space (including fragments of the old pipe) larger than the old pipe is formed by the bursting mole to accommodate the new pipe attached to the rear end of the mole 3.

3. 5 In the method illustrated in Figure 3, the new pipe 2 is in the form of short pipe sections. As shown in Figures 1 (a), (b) and (c), each pipe section 2 is provided with a longitudinal detachable portion 6 constituting a removable part of the periphery of the pipe in parallel to the axial direction thereof. In the example illustrated, stepped portions 7 are provided on the edges of the longitudinal detachable portion 6 which engage with correspondingly stepped portions provided in the periphery of the pipe 2. Each of the stepped portions 7 of the pipe section 2 and the detachable portion 6 are provided with aligned bores 7a. The bores are provided with an internal screw thread 7b. The stepped portions 7 of the pipe section 2 and the detachable portion 6 are secured together by a screw 8 (or other fastening member such as a bolt) having a shaft provided with a screw thread corresponding to that provided in the bores 7a. A resilient sealing member 9 (as shown in Figure 2) in the form of a rubber strip is interposed between the stepped portions 7 to provide a satisfactory seal between the pipe section 2 and the detachable portion 6.

Figures 3A-C illustrate the process of forming a new pipe line by joining together individual pipe section 2.

The steps involved in the illustrated pipe replacement method are as follows:

1. A power line (in the form of an air hose) 10 extending from a power source 11 (in the form of a compressor) for driving the mole is joined to the rear thereof and a cable 5 extending from a winch (not shown) is joined to the front of mole 3. The mole 3 is then moved forward with the tip end of the mole intruding into the old pipe 1 and the old pipe is burst by the mole 3. The air hose 10 supplies compressed air to a driving means (in the form of an air hammer) incorporated in the head of the mole, thereby advancing the mole 3 into the space vacated by the old pipe 1 2. As illustrated in Figures 3B (a - d), the longitudinal detachable portion 6 is removed from a pipe section 2 to be joined to the rear of the mole 3. The air hose 10 is then inserted into the new pipe and the longitudinal detachable portion 6 is secured in place in the periphery of the pipe 2 by the screw 8. The mole and the new pipe section 2 are integrally secured to each other by suitable means, such a wire, to form a sealed connection. Furthermore, as shown in Figure 3, the mole 3 and the new pipe section 2 are moved forward together into the space formed by the burst old pipe 1. The air hose 10 is alternately let out and rewound from a hose reel 12 when a pipe section 2 is to be fitted to the new pipe line.

The air hose 10 is then- inserted into a new pipe section 2 which is then joined in the same manner as above to the rear end of the preceding pipe section whereby the extension from the starting pit to the destination pit is easily and neatly achieved.

By the above process, pipe sections can be added to the new pipeline without interrupting the air supply to the bursting mole.

A method according to the present invention allows replacement work to be efficiently carried out even when the starting Pit is narrow and has a relati ' vely small working area.

A method according to the present invention results in, among other things, the reduction of working space, shortening of working time, omission of certain working instruments, protection of the internal surfaces of the new pipes and an improvement in the efficiency of air supply to the bursting mole.

The new pipe may be either a replacement pipe for the old pipe or a sheath for the replacement pipe.

Claims

CLAIMS:

A method of replacing an old buried pipe with a new pipe comprising a plurality of pipe sections, which method comprises attaching successive new pipe sections to a bursting mole having a cylindrical body whose external diameter is larger than the existing old pipes and moving the bursting mole forward so that a head of the bursting mole intrudes into the old pipe and bursts it to provide an enlarged space for the new pipe following the bursting mole, which method further includes supplying power to a driving means carried by the bursting mole through a power line from a power source and temporarily detaching a longitudinal portion of each successive pipe section in order to introduce the power line into the pipe sections without disconnecting the line from the bursting mole.
2. A method according to claim 1, wherein -the method further comprises forming the new pipe from a plurality of short pipe sections having a strength able to endure the application of the compressive force and connectin the pipe sections to one another in a starting pit.
3. A method of replacing an old buried pipe with a new pipe substantially as hereinbefore described with reference to the accompanying drawings.
4. Apparatus for replacing an old buried pipe with a new pipe comprising a plurality of pipe sections, which apparatus comprises, a bursting mole having a cylindrical body with an external diameter which is larger than the existing old pipe, means for attaching successive pipe sections to the bursting mole, a power source for supplying power through a power line to a driving means 11 I t carried by the bursting mole to move the bursting mole forward so that a head of.the mole intrudes into the old pipe and bursts it, and means for attaching successive pipe sections behind bursting mole wherein each pipe section is adapted to be coupled to a preceding pipe section as the mole advances and is provided with a detachable section defining a longitudinal detachable portion extending the length of the pipe section which can be temporarily detached from the pipe section in order to introduce the power line into the pipe section without disconnecting the power line from the bursting mole.
5. Apparatus according to claim 4, wherein each pipe. section and related detachable portion are provided with correspondingly shaped stepped portions.
6. Apparatus according to claim 5, wherein the stepped portions are secured together by a fastening member.
7. Apparatus according to claim 5 or 6, wherein a resilient sealing member is interposed between the stepped portions in order to provide a seal between the pipe section and the related detachable portion.
8. Apparatus for replacing an old buried pipe with a new pipe substantially as hereinbefore described with reference to and as shown in Figures 1 to 3 of the accompanying drawings.
9. Any novel feature described herein.

or combination of features PubhBhed 1989 at The Patent Office, State House, 66 71 High Holborn, London WCIR 4TP. Further copies may be obtained from The Patent OMce Sales Branch, St Mary Cray, Orpington. Rent BRS 3RD Printed ky Multaplex techniques ltd, St Mary Cray, Rent, Con- 1/87