WO2001027433A1

WO2001027433A1 - Method and apparatus for replacing a conduit

Info

Publication number: WO2001027433A1
Application number: PCT/GB2000/003947
Authority: WO
Inventors: Richard Geall
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-10-14
Filing date: 2000-10-13
Publication date: 2001-04-19
Anticipated expiration: 2002-04-14
Also published as: AU7805700A

Abstract

A method of and apparatus for replacing an existing underground conduit (1), e.g. pipe or cable, with minimal excavation is disclosed. A hydraulic ram (4) is used to inject sleeving along the path of the existing conduit (1) and a new conduit can then be run in with or without removing the existing conduit (1). The sleeving may be rotated and water may be forced through the sleeving so as to emerge at the front end, thereby assisting in progressing the sleeving through the earth.

Description

METHOD AND APPARATUS FOR REPLACING A CONDUIT

The present invention relates to a method of replacing, renewing or servicing an existing underground conduit and to apparatus for replacing an existing underground conduit . The underground conduit may be a utility service pipe, cable, duct or other continuous conduit .

Conventional methods of replacing an underground conduit invariably involve a significant amount of excavation which causes disruption. Such methods are also time consuming and expensive. Conventional methods by open excavation involve the risk of damage to other apparatus, pipes, cables, etc. as a new clear route has to be found and exposed. Other methods of replacement tend to be of limited use due to the close proximity of other apparatus, pipes, cables, etc. which can be easily damaged by impact and/or by vibrations from machinery in close proximity or actual contact. Furthermore, a new clear route still has to be found and this can be problematic.

It is therefore desired to provide an improved method of replacing a continuous conduit.

According to the present invention there is provided a method of replacing, renewing or servicing an existing underground conduit, comprising the steps of: placing a sleeve on the existing conduit; moving said sleeve along said existing conduit; and connecting at least one additional sleeve to the sleeve.

Preferably, the existing underground conduit is a utility or mains pipe, cable or duct.

Preferably, a fluid is passed within or through the sleeve and/or the additional sleeve. The fluid, preferably water, may emerge at the end of a sleeve and/or may exit via holes in the sleeving.

Preferably, the sleeve and/or the additional sleeve are rotated to aid the progression of the overboring pipe along the existing conduit.

The sleeve may have a boring portion for boring a hole, and/or it may have a cutting portion.

Hydraulic means such as a hydraulic ram or the arm of an excavating machine or digger may be used to move e.g. push or pull the sleeve along the conduit.

According to a particularly preferred embodiment the sleeve and/or the additional sleeve are manufactured from polypropylene . The at least one additional sleeve may be provided with a thread so that it can be screwed to the sleeve which is also preferably provided with a thread.

The existing conduit may be withdrawn once the sleeving has been introduced, or as the sleeving is being introduced. In one embodiment the sleeve and the at least one additional sleeve are initially left in place and the existing conduit is withdrawn through the sleeve and the at least one additional sleeve. In an alternative embodiment, the sleeve and the at least one additional sleeve are removed and then the existing conduit is withdrawn.

The new or replacement conduit may be introduced as the sleeve and the at least one additional sleeve are being removed. Alternatively, the new or replacement conduit is introduced after the sleeve and the at least one additional sleeve have been removed.

An expander portion may be provided for altering the size or diameter of the conduit. The expander portion may comprise a cone shaped expander, and may be attachable to the sleeve and/or said at least one additional sleeve.

Apparatus for replacing an existing underground conduit is disclosed, comprising: a sleeve having a cutting or boring portion; and moving means for moving said sleeve along said existing conduit.

The moving means may be arranged to hydraulically move the sleeve. The moving means may comprise an hydraulic ram having one or more jaws for gripping the sleeve and/or the existing underground conduit.

At least one additional sleeve may be provided which in use is attached to the sleeve. Preferably, the sleeve and/or the at least one additional sleeve are substantially rigid. Further preferably, the sleeve and/or said at least one additional sleeve are threadably connectable. The sleeve and/or the at least one additional sleeve may be made from mild steel, another metal, plastic, polypropylene or medium-density polyethylene.

A method of replacing, renewing or servicing an underground pipe or conduit is disclosed, comprising the steps of: placing a first sleeve portion over an exposed portion of the pipe or conduit; hydraulically pushing or pulling the first sleeve portion along the underground pipe or conduit; and attaching a second sleeve portion to the first sleeve portion; and hydraulically pushing or pulling both the first sleeve portion and the second sleeve portion along the underground pipe or conduit. Either the first or the second sleeve portion may be provided with boring means for boring a hole.

In one embodiment a hole at one or both ends of the underground pipe or conduit may be excavated or otherwise dug. Apparatus for introducing a new underground pipe along the path of an existing underground pipe is also disclosed comprising: a plurality of sleeves which are connectable to one another; and hydraulic means for pushing and/or pulling the plurality of sleeves along the underground pipe or cable.

Preferably, means may be provided for rotating the plurality of sleeves.

Preferably, means may be provided for introducing a fluid into the plurality of sleeves for assisting in progressing the plurality of sleeves along the underground pipe or cable .

At least one of the sleeves may have a cutting or boring portion. At least one of the sleeves may have an expanding portion.

Apparatus for servicing an underground conduit is also disclosed comprising: a generator for providing power; a plurality of pipe sleeving; and pipe sleeving moving means comprising at least two hydraulic cylinders for operating a set of jaws for gripping and pushing and/or pulling the pipe sleeving along the path of the existing underground conduit. A method of replacing an underground pipe without excavating the pipe is disclosed, comprising the steps of: identifying an old underground pipe having a first external diameter to be replaced; introducing a plurality of sleeves having a second external diameter larger than the first external diameter along the length of the old underground pipe; withdrawing the old underground pipe after the sleeves have been introduced underground; and introducing a replacement underground pipe along the path of the old underground pipe . A method of sleeving an existing underground pipe or cable is disclosed, comprising: excavating one or more ends of the underground pipe or cable without excavating the majority of the pipe or cable; and passing a plurality of sleeves along the underground pipe or cable using the underground pipe or cable as a guide .

Hydraulic means may be used to pass the sleeves along the underground pipe or cable .

A substantially no-dig method of replacing an underground service is disclosed, comprising: guiding a plurality of sleeves along the path of the underground service whilst the underground service remains substantially in si tu; withdrawing the underground service from inside the sleeving; and running in a replacement underground service within the sleeving.

A portion of the sleeves may have a cutting or boring portion.

A method of guiding sleeving along an existing underground service is disclosed, comprising the steps of: excavating one or more ends of the existing service; attaching a first sleeve portion to the existing service; guiding the first sleeve portion along the existing service; attaching a second sleeve portion to the first sleeve portion; and guiding both the first and second sleeve portions along the existing service.

A replacement service may be introduced inside the first and second sleeve portions. A replacement service may be introduced as the first and second sleeve portions are withdrawn.

One of the advantages of the present invention is that it utilises the route of an existing conduit hence guaranteeing the provision of a clear route . The present invention also avoids contacting other apparatus and conduits which, according to current regulations, must be at least 150mm away from the existing conduit. Furthermore, if the present invention is used to replace a cable, then any protection which may already be present above the cable remains in position and remains effective. In addition the replacement cable will be in contact with the surrounding earth and so is able to dissipate any heat generated which is an important design consideration. Various embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawing in which:

Fig. 1 shows an arrangement for renewing an existing service conduit; and Fig. 2 is an enlargement of the view at X-X of Fig.

1.

With reference to Fig. 1, an existing pipe, cable, duct or other continuous conduit 1 requiring renewal, replacement or servicing is located using conventional techniques. According to a preferred embodiment a launch pit 2 is then dug or excavated at one end of the conduit 1 and a reception pit 3 is dug or excavated at the other end of the conduit 1. The conduit 1 is then cut or disconnected in the launch pit 2 to provide an end.

An overboring unit 4 which in a preferred embodiment comprises an hydraulic ram is then positioned in the launch pit 2. The overboring unit 4 may be connected to a power source 5 such as a generator by means of a connector or hose 6. Preferably, the hydraulic ram is positioned in the launch pit 2 so that it is generally level with the existing conduit 1. As shown in greater detail in Fig. 2, a first pipe sleeve 7 of generally greater external diameter than that of the existing conduit 1 is chosen and is fitted over the end of the existing conduit 1 or other service to be replaced, renewed or serviced. Dependent upon the ground conditions the first sleeve 7 may have a cutting edge 8. Alternatively, the first sleeve 7 may have an end that is shaped or otherwise sharpened to assist with the progression of the sleeve 7 through the ground. For example, the first sleeve 7 may have an end which assists in boring through compacted soil. It will also be appreciated that in less preferred arrangements the cutting or boring means does not have to provided right at the very tip of the first sleeve 7. For example, the cutting or boring means could be provided along the length of the sleeve 7. In other arrangements a cutting or boring edge 8 may be provided at the tip of the sleeve 7 and additional means disposed further along the sleeve body may be provided for assisting the passage of the sleeve 7 through the ground. The overboring unit 4 is preferably used to push the first sleeve 7 over and along the existing conduit 1 which may, for example, be a water pipe. According to a less preferred embodiment, the first sleeve 7 can be placed at the opposite end of the existing service 1 to that of the overboring unit 4, and the first sleeve 7 can then be pulled towards the overboring unit 4. Preferably a hydraulic ram is used to push (or pull) the first sleeve 7 along and over the existing conduit 1. In one embodiment the overboring unit 4 comprises two or more hydraulic cylinders (not shown) which operate a set of jaws (not shown) . The set of jaws are used to grip the first sleeve 7 and push (or pull) the first sleeve 7 along the existing conduit 1. The overboring unit 4 preferably has a push/pull force of at least 3 tons .

The first sleeve 7 preferably consists of a rigid pipe which preferably has a thread at one end enabling a second sleeve to be connected thereto. Further sleeves can be connected to the second sleeve, thereby forming sleeving approximately as long as the existing conduit 1. Although a threaded connection is preferred for the first 7, second and any subsequent sleeves, it will be readily appreciated that other forms of connector arrangement could be used, such as for example a snap- lock arrangement. The first sleeve 7 may be made from mild steel, other metals and alloys, plastics, carbon fibre, medium-density polyethylene (MDPE) or other materials. The second sleeve may be made from the same material as the first sleeve, or alternatively it may be made from a different material. For example, in one embodiment the first sleeve 7 which may have a cutting or boring function may be made from steel, whereas the second and any subsequent sleeves may be made from plastic .

The use of polypropylene as a material for making the sleeving is particularly preferred since it has the strength and flexibility to be pushed and rotated over the host. The pipe may also be butt welded to join several pipes together. Ideally, the sleeving or overboring pipe should be flexible with a bend of up to 40% over a 1 metre length, resistant to torque, not be brittle and should be able to be joined without affecting any of its properties or its performance as a continuous pipe. The pipe material should also preferably allow a colour pigment to be added and the pipe should be able to accept a thread. Further preferred properties of the overboring sleeving are that the pipe should be resistant to longitudinal compression, and should be able to be pressurised and withstand up to 15 bar internal pressure. Although it is preferred that the first sleeve 7 is provided with means 8 for cutting or boring through the ground, it will also be appreciated that in a less preferred arrangement the second sleeve or a subsequent sleeve may additionally or alternatively be provided with such means 8.

A hydraulic ram may be used to push (or pull) the first sleeve 7 over the existing pipe or conduit 1, and once the first sleeve section 7 has been pushed (or pulled) almost its full length, the jaws on the ram are released, a second sleeve section is screwed or otherwise connected to the first sleeve section 7, and the process is repeated. Third, fourth and further sleeves may then be attached or connected in due course . The sleeves preferably generally or substantially follow the route of the existing service 1 and are generally or substantially kept on line by the existing service 1. The process continues until the desired length of the existing service 1 has been sleeved. According to the preferred embodiment, the process is continued until the majority of the existing service 1 has been sleeved, further preferably substantially the whole length of the existing service 1 has been sleeved.

Once the desired length of the existing service 1 has been sleeved, the existing service 1 can be withdrawn from within the protective or shielded environment provided by the sleeving. Alternatively, depending upon ground conditions, the sleeving process can be reversed leaving a hole of greater diameter than that of the existing service 1. The existing service 1 can then be simply withdrawn from the hole. The process can be reversed by turning the hydraulic rams so that the pushing action becomes a pulling action (or vice versa) . If it is desired to replace the existing service 1 with a replacement service, then a replacement service can be pushed (or pulled) through the hole left subsequent to the withdrawal of the sleeving and existing service 1. Alternatively, a replacement service can be introduced as the sleeving is being withdrawn. For example, if the sleeving is being withdrawn by being pulled by the overboring unit 4 into the launch pit 2, then the replacement service can be introduced through the reception pit 3. The replacement service may be attached to the sleeving as it is being withdrawn so that the same action removes the sleeving and also introduces the replacement service.

Other embodiments are also contemplated. For example, it will be appreciated that the existing service does not need to be withdrawn if the sleeving and/or replacement service have an internal diameter which is larger than the external diameter of the existing service 1 so that an annular space is provided between the replacement service and the existing service 1.

In a further embodiment, the size of the service can be expanded or otherwise altered by using an expander which can, for example, be attached to the far end of the sleeving as it is being withdrawn by pulling. The expander may comprise a cone shaped expander.

In other less preferred embodiments if the sleeving if of sufficient diameter then it can be left in the ground once it has been deployed and a new conduit could be introduced inside the sleeving with or without removing the existing conduit.

The size of the sleeving used is generally determined by ground conditions and the size and power of the hydraulic system being used. The pipe sleeving may be pushed in a dry condition i.e. without using a lubricant. However, according to a particularly preferred embodiment, water or another liquid or fluid may be introduced preferably into the inside of the overboring pipe, under variable pressure/flow conditions. In one embodiment water may be introduced at a pressure of approx. 1200 psi (8268 kPa) and at a flow of approx. 5 gallons per minute (22.5 litres per minute) . The method of supplying water is via a tank with a petrol/generator driven pump, directly into the annulus of the overboring pipe. In other embodiments liquid may be introduced at different flows and pressures up to a maximum between 2000-5000 psi (13780-34450 kPa) . It will be appreciated that fluids other than water may be used.

The pipe or sleeving which is placed over the existing conduit may also be rotated using e.g. a geared drive from a compressor. The speed of rotation may be varied. Alternatively, the pipe or sleeving may be rotated using an hydraulic drive and again the speed of rotation may be varied. In one embodiment the speed of rotation may be set in the region of approx. 30 rpm, and in other embodiments the speed- of rotation is preferably kept low so as not to exceed more than approx. 250rpm. Rotation of the overboring pipe has been found to be particularly effective as a means of easing progress of the sleeves and avoiding snagging of any irregular edges. The rotation may also be used to facilitate cutting at the front of the overboring pipe or sleeving. In one embodiment hydraulic force can also be used to push the overboring pipe over the host using an addition to the end of the excavating arm of an excavating machine or digger such as a JCB or Kubota. A cutting head may also be attached to the overboring pipe, and the pipe may be threaded enabling attachments to be attached thereto.

Three different sizes of overboring pipe may be used: (i) 0 to 30mm diameter which may be used mainly small diameter services to individual properties; (ii) 30mm to 70mm diameter for large building services and feeds to groups of properties/buildings; and (iii) >70mm diameter for replacement of main pipes, cables, and conduits .

The typical distances involved with each type of sleeving vary but as a rough guide, 0 to 30mm diameter sleeving may be used up to approx. 30 metres, 30mm to 70mm diameter sleeving up to approx. 100-150 metres, and 70mm and above diameter sleeving up to distances of 200 metres or more.

Claims

1. A method of replacing, renewing or servicing an existing underground conduit, comprising the steps of: placing a sleeve on the existing conduit; moving said sleeve along said existing conduit; and connecting at least one additional sleeve to said sleeve.

2. A method as claimed in claim 1, wherein said existing underground conduit is a utility or mains pipe, cable or duct .

3. A method as claimed in claim 1 or 2 , further comprising the step of passing a fluid within or through said sleeve and/or said additional sleeve.

4. A method as claimed in claim 1, 2 or 3 , further comprising the step of rotating said sleeve and/or said additional sleeve.

5. A method as claimed in any preceding claim, further comprising the step of providing said sleeve with a boring portion for boring a hole.

6. A method as claimed in any preceding claim, further comprising the step of providing said sleeve with a cutting portion.

7. A method as claimed in any preceding claim, further comprising the step of using hydraulic means to move said sleeve along said conduit .

8. A method as claimed in claim 7, wherein said hydraulic means pushes said sleeve.

9. A method as claimed in claim 7 or 8 , wherein said hydraulic means pulls said sleeve.

10. A method as claimed in claim 7, 8 or 9, wherein said hydraulic means comprises a hydraulic ram.

11. A method as claimed in any of claims 7-10, wherein said hydraulic means comprises the arm of an excavating machine .

12. A method as claimed in any preceding claim, wherein said sleeve and/or said additional sleeve are manufactured from polyolefin, preferably polypropylene.

13. A method as claimed in any preceding claim, further comprising the step of screwing together said at least one additional sleeve to said sleeve.

14. A method as claimed in any preceding claim, further comprising the step of withdrawing said existing conduit .

15. A method as claimed in claim 14, wherein said sleeve and said at least one additional sleeve are initially left in place and said existing conduit is withdrawn through said sleeve and said at least one additional sleeve.

16. A method as claimed in claim 14, wherein said sleeve and said at least one additional sleeve are removed and then said existing conduit is withdrawn.

17. A method as claimed in any preceding claim, further comprising the step of introducing a new or replacement conduit.

18. A method as claimed in claim 17, wherein said new or replacement conduit is introduced as said sleeve and said at least one additional sleeve are being removed.

19. A method as claimed in claim 17, wherein said new or replacement conduit is introduced after said sleeve and said at least one additional sleeve have been removed .

20. A method as claimed in any preceding claim, further comprising providing an expander portion for altering the size or diameter of the conduit.

21. A method as claimed in claim 20, wherein said expander portion comprises a cone shaped expander.

22. A method as claimed in claim 20 or 21, wherein said expander portion is attachable to said sleeve and/or said at least one additional sleeve.

23. Apparatus for replacing an existing underground conduit, comprising: a sleeve having a cutting or boring portion; and moving means for moving said sleeve along said existing conduit.

24. Apparatus as claimed in claim 23, wherein said moving means is arranged to hydraulically move said sleeve .

25. Apparatus as claimed in claim 24, wherein said moving means comprises an hydraulic ram having one or more jaws for gripping said sleeve and/or said existing underground conduit .

26. Apparatus as claimed in claim 23, 24 or 25, further comprising at least one additional sleeve which in use is attached to said sleeve.

27. Apparatus as claimed in claim 26, wherein said sleeve and/or said at least one additional sleeve are substantially rigid.

28. Apparatus as claimed in claim 26 or 27, wherein said sleeve and/or said at least one additional sleeve are threadably connectable .

29. Apparatus as claimed in claim 26, 27 or 28, wherein said sleeve and/or said at least one additional sleeve are made from mild steel .

30. Apparatus as claimed in claim 26, 27 or 28, wherein said sleeve and/or said at least one additional sleeve are made from metal .

31. Apparatus as claimed in claim 26, 27 or 28, wherein said sleeve and/or said at least one additional sleeve are made from plastic.

32. Apparatus as claimed in claim 31, wherein said sleeve and/or said at least one additional sleeve are made from polypropylene .

33. Apparatus as claimed in claim 26, 27 or 28, wherein said sleeve and/or said at least one additional sleeve are made from medium-density polyethylene.

34. A method of replacing, renewing or servicing an underground pipe or conduit, comprising the steps of: placing a first sleeve portion over an exposed portion of said pipe or conduit; hydraulically pushing or pulling said first sleeve portion along said underground pipe or conduit; and attaching a second sleeve portion to said first sleeve portion; and hydraulically pushing or pulling both said first sleeve portion and said second sleeve portion along said underground pipe or conduit .

35. A method as claimed in claim 34, further comprising providing either said first or said second sleeve portion with boring means for boring a hole.

36. A method as claimed in claim 34 or 35, further comprising excavating or otherwise digging a hole at one or both ends of said underground pipe or conduit .

37. Apparatus for introducing a new underground pipe along the path of an existing underground pipe comprising: a plurality of sleeves which are connectable to one another; and hydraulic means for pushing and/or pulling said plurality of sleeves along said underground pipe or cable .

38. Apparatus as claimed in claim 37, further comprising means for rotating said plurality of sleeves.

39. Apparatus as claimed in claim 37 or 38, further comprising means for introducing a fluid into said plurality of sleeves for assisting in progressing said plurality of sleeves along said underground pipe or cable .

40. Apparatus as claimed in claim 37, 38 or 39, wherein at least one of said sleeves has a cutting or boring portion .

41. Apparatus as claimed in any of claims 37-40, wherein at least one of said sleeves has an expanding portion.

42. Apparatus for servicing an underground conduit comprising: a generator for providing power; a plurality of pipe sleeving; and pipe sleeving moving means comprising at least two hydraulic cylinders for operating a set of jaws for gripping and pushing and/or pulling said pipe sleeving along the path of the existing underground conduit.

43. A method of replacing an underground pipe without excavating said pipe, comprising the steps of: identifying an old underground pipe having a first external diameter to be replaced; introducing a plurality of sleeves having a second external diameter larger than said first external diameter along the length of said old underground pipe; withdrawing said old underground pipe after said sleeves have been introduced underground; and introducing a replacement underground pipe along the path of said old underground pipe.

44. A method of sleeving an existing underground pipe or cable, comprising: excavating one or more ends of said underground pipe or cable without excavating the majority of said pipe or cable; and passing a plurality of sleeves along said underground pipe or cable using said underground pipe or cable as a guide.

45. A method as claimed in claim 44, further comprising using hydraulic means to pass said sleeves along said underground pipe or cable .

46. A substantially no-dig method of replacing an underground service, comprising: guiding a plurality of sleeves along the path of said underground service whilst said underground service remains substantially in si tu; withdrawing said underground service from inside said sleeving; and running in a replacement underground service within said sleeving.

47. A method as claimed in claim 46, wherein a portion of said sleeves has a cutting or boring portion.

48. A method of guiding sleeving along an existing underground service, comprising the steps of: excavating one or more ends of said existing service; attaching a first sleeve portion to said existing service; guiding said first sleeve portion along said existing service; attaching a second sleeve portion to said first sleeve portion; and guiding both said first and second sleeve portions along said existing service.

49. A method as claimed in claim 48, further comprising introducing a replacement service inside said first and second sleeve portions.

50. A method as claimed in claim 48, further comprising introducing a replacement service as said first and second sleeve portions are withdrawn.