GB2227543A

GB2227543A - Lining pipework

Info

Publication number: GB2227543A
Application number: GB8928168A
Authority: GB
Inventors: David John Hill; Steven John Dudley; John Alan Denning; Alan Lloyd Headford
Original assignee: Victaulic Co PLC
Current assignee: Victaulic Co PLC
Priority date: 1988-12-22
Filing date: 1989-12-13
Publication date: 1990-08-01
Anticipated expiration: 2009-12-13
Also published as: GB8928168D0; GB2227543B; GB8829974D0

Abstract

The invention provides a method of and apparatus for lining underground pipework 8 via a downwardly extending access or manhole shaft 7 in which a liner pipe 1 is passed downwardly into the access shaft 7, and is deformed within the access shaft 7 at the level of the pipework 8 by rollers 10, 11 so as at least partially to flatten the liner pipe 1 and bend it eg to kidney shape across the generally flattened plane to a generally horizontal disposition, the liner pipe 1 being caused or permitted to take up its original pipe shape configuration eg by rollers 12 and passed into the pipework 8 from the access shaft 7. Upper rollers 5, 6 may be provided to bend the liner pipe 1 in reverse manner and to feed the liner pipe along a Z-shaped path. <IMAGE>

Description

Apparatus for and Methods of Lining Pipework This invention relates to apparatus for and methods of lining pipework, especially underground pipework, and more particularly although not exclusively, to the relining of old or leaky underground pipework such as sewers, water mains and service pipes.

Various techniques for carrying out such relining are known, frequently using polyethylene pipe for this purpose, by various methods, after renovation or descaling of the pipework if necessary.

One method involves excavating a short trench down to the level of the existing pipework, breaking into the pipework, carrying out renovation and descaling as necessary, and then inserting into the pipework a new polyethylene pipe liner of smaller outside diameter than the internal diameter of the existing pipework, the positioning being carried out for example by means of a steel hauling cable. Such a technique provides a loosely fitting liner with a small but measure able annular gap between liner and original pipework.

A variation on the just mentioned method is a "diameter reduction" technique in which the liner pipe before insertion is reduced in diameter by rolling or swaging, and then a "diameter recovery" technique is used after insertion of the liner pipe into the pipework by means of heat and/or pressure, or by means of natural time shape reversion.

The two known methods mentioned above both have the disadvantage that excavation to a certain extent of the ground around the existing pipework is necessary to give access, since it is not in practice possible with the usual dimensions of the pipework systems to insert the liner pipe via existing manhole access points to pipework, usually particularly owing to the small bend radii required for the liner pipe to bend from the vertical manhole or access shaft into the horizontal pipework itself.

It is an object of the present invention to provide a lining system which overcomes or at least substantially reduces the above mentioned disadvantage.

In accordance with one aspect of the present invention, there is provided a method of lining underground pipework via a downwardly extending access or manhole shaft comprising the steps of passing a liner pipe downwardly into the access shaft, deforming the liner pipe within the access shaft at the level of the pipework so as at least partially to flatten the liner pipe and bending it across the generally flattened plane to a generally horizontal disposition, causing or permitting it to take up its original pipe shape configuration and passing it into the pipework from the access shaft.

Where there is sufficient tolerance between the liner pipe and the pipework at least part of the step of causing or permitting the liner pipe to take up its original configuration may take place within the pipework.

Preferably, however, this step is completed within the access shaft before the liner pipe moves into the pipework The invention may include the additional preliminary steps of deforming the liner pipe when in a generally horizontal disposition at the upper end of the shaft so as at least partially to flatten the pipe in a generally horizontal plane, and bending the liner pipe downwardly and then passing the pipe downwardly into the access shaft.

In accordance with another aspect of the present invention, there is provided apparatus for relining underground pipework comprising a pipe deforming roll arrangement adapted for location at the lower end of a downwardly extending access or manhole shaft, the rolls being so inter-related as to enable liner pipe passed down the access shaft being engaged by the lower roll arrangement, partially flattened thereby, and bent to pass into underground pipework extending from the lower end of the access shaft.

The apparatus may include an upper pipe deforming roll arrangement adapted for location at the upper end of the downwardly extending access or manhole shaft, the rolls being so inter-related as to enable liner pipe, generally horizontally disposed, to engage the first roll arrangement and be partially flattened thereby and bent to pass down the access shaft to the lower pipe deforming roll arrangement.

Desirably the roll arrangments are adapted to deform the liner pipe to a kidney shaped cross section at the same time as bending the pipe along its length and in the direction of the concave side of the kidney section. Such a configuration imposes minimal strain on the pipe walls whilst still providing an adequately partially flattened deformation of the pipe.

A convenient arrangement is for the liner pipe to move into the pipework via the access shaft in zig zag fashion in the same generally vertical approximate plane.

In this case (where a kidney shaped pipe deformation is formed) the rolls at top and bottom of the access shaft will be arranged to provide cross section deformations of opposite sense, and a further roll arrangement may be located in the access shaft between the two sets of deforming rolls for guidance purposes which permit or assist in the removal of the first distortion to the liner pipe caused by the first set of rolls.

A further roll arrangement may be provided adjacent to the entrance to the pipework after the second set of rolls adapted to act upon the side walls of the liner pipe and assist in the reversion to the normal configuration of the pipe.

In order that the invention may be more readily understood one embodiment thereof will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic side view of apparatus for a relining method for pipework by means of the present invention; Figure 2 is a schematic illustration of driving mechanisms for lining pipe for use in the technique shown in Figure 1; Figure 3 illustrates a final straightening set of rolls in the arrangement of Figure 1; and Figures 4 to 7 show the lining pipe cross section at the upper deforming rolls, the guiding rolls, the lower deforming rolls and the final straightening rolls, respectively.

As can be seen in Figure 1 polyethylene pipe 1 is delivered to the relevant pipework relining site in considerable lengths coiled upon drums 2, thereby eliminating or reducing the need for butt welding lengths of pipe for use as an elongate lining. In practise a drag chain (not shown) may be attached to the start of the coil of liner pipe to pull the pipe through the assembly of rollers used in the method of the present invention into the pipework.

As can be seen in Figure 2, the pipe is first passed through a set of drive jaws 3 which positively push the liner pipe 1 forward at a controlled speed. The drive jaws are so designed that minimal slippage will occur even if the pipe on site is wet and muddy. These can be of any known design for such drive jaws.

In Figure 1 it can be seen that the liner pipe is driven through a set 4 of deforming rollers at the upper end of an access shaft 7 opening into pipework 8. The deforming rollers may comprise a plurality of ball rolls or a ball roll 5 and plain roll 6 (as illustrated) which alter the section of the pipe into a partially flattened shape, and preferably into the kidney shape as shown in Figure 4, or alternatively into a flattened figure "8" shape (not shown). At the same time the flattened pipe is bent through an angle of 900 or greater thereby allowing it to pass downwardly into the access shaft 7 for the pipework 8 to be relined. It is to be seen that the bending is assisted greatly by the kidney shape of the deformed pipe, where the concave arc of the kidney is on the inside of the bend.

Part way down the access shaft 7, as the flattened pipe commences to revert to circular cross section it passes through a set of guide rolls 13 which permit the reversion as shown in Figure 5.

As can be seen in Figure 1, at the foot of the access shaft 7 the pipe is bent through a further angle of 900 or greater by being forced through a further set 9 of deforming roll 10 and plain roll 11 corresponding to those at the upper end of the manhole opening but operating in the opposite sense so that the pipe is now deformed into a kidney shape of reverse formation from that previously formed as shown in Figure 6, the bending again being assisted by means of the concave arc of the kidney shape on the inside of the bend.

As can be seen from Figure 3, the kidney shape pipe passes through either a re-rounding tool or tas shown) a set 12 of rolls which bear upon the outer walls of the deformed kidney shaped pipe and assist in the natural pipe reversion to circular cross section, within the access shaft in the illustrated embodiment, as shown in Figure 7.

With the arrangement illustrated, the installed liner pipe recovers fully to its initial circular cross section without any further processing. However, the technique may be used and form part of other processes such as that providing a temporary reduction of diameter of the liner pipe prior to feeding into the shaft 7 and pipework 8 by means of a rolling or swaging technique. Where such a technique is used heating and/or pressure may be used within the liner pipe after installation to recover the circular section diameter of the liner pipe towards its original pre-reduced diameter so as to ensure a tight fit within the pipework.

By means of the invention we enable a polyethylene liner pipe to be formed and inserted into a suitable access shaft for underground pipework without requiring any excavation of that manhole opening. The liner pipe can be subsequently recovered to its original shape at insertion into the pipe line, and this recovery may be achieved without the need for the application of heat and/or pressure except where the technique is used in combination with a pipe diameter reduction technique as described hereinabove.

We would mention at this point one earlier proposed technique for providing lining pipes for pipework which involved the provision of a lining pipe collapsed, off site, into a tight "U" shape (in section) and subsequently, after insertion of the still collapsed pipe into the pipework, restore the original pipe shaped configuration to the liner pipe by means of pressure and/or heat. As will be appreciated from the above description, the technique and apparatus of the present invention circumvents the need to deliver large quantities of collapsed pipe to the work site, and additionally, the requirement of heat and/or pressure means to restore the correct section of the liner pipe after it has been threaded into the post pipework, except as previously discussed when a pipe diameter reduction technique is additionally used.

It is to be understood that the foregoing is merely exemplary of methods of and apparatus for relining underground pipework in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention

Claims

CLAIMS: 1. A method of lining underground pipework via a downwardly extending access or manhole shaft comprising the steps of passing a liner pipe downwardly into the access shaft, deforming the liner pipe within the access shaft at the level of pipework so as at least partially to flatten the liner pipe, and bending it across the generally flattened plane to a generally horizontal disposition, causing or permitting it to take up its original pipe shape configuration, and passing it into the pipework from the access shaft.
2. A method as claimed in Claim 1 wherein the step of causing or permitting the line of pipe to take up its original pipe shape configuration after bending it into said generally horizontal disposition is completed within the access shaft before the liner pipe passes into the pipe work.
3. A method as claimed in Claim 1 wherein the step of causing or permitting the line of pipe to take up its original pipe shape configuration after bending it to said generally horizontal disposition takes place partially within the pipework and partially within the access shaft.
4. A method as claimed in any one of the preceding claims including additional preliminary steps of deforming the liner pipe, when in a generally horizontal disposition at the upper end of the shaft, so as at least partially to flatten the pipe in a generally horizontal plane, and bending the liner pipe downwardly and then passing the pipe downwardly into the access shaft.
5. A method as claimed in any one of the preceding claims wherein the deformation of the liner pipe is, in each instance, to a kidney-shaped cross-section, and the pipes are bent along the length of the pipe in each instance in the direction of the concave side of the kidney section.
6. A method of lining underground pipework substantially as herebefore described with reference to the accompanying drawings.
7. Apparatus for relining underground pipework comprising a pipe deforming roll arrangement adapted for location at the lower end of a downwardly extending access or manhole shaft, the rolls being so inter-related as to enable liner pipe passed down the access shaft being engaged by the lower roll arrangement, partially flattened thereby, and bent to pass into underground pipework extending from the lower end of the access shaft.
8. Apparatus as claimed in Claim 7 including an upper pipe deforming roll arrangement adapted for location at the upper end of the downwardly extending access or manhole shaft, the rolls being so inter-related as to enable liner pipe, generally horizontally disposed, to engage the further roll arrangement and be partially flattened thereby and bent to pass down and into the access shaft for engagement by the lower roll arrangement.
9. Apparatus according to Claim 7 or 8 wherein the roll arrangements are adapted to deform the liner pipe to a kidney-shaped cross-section at the same time as bending the pipe along its length and in the direction of the concave side of the kidney section.
10. Apparatus according to any one of Claims 7 to 9 wherein the upper and lower roll arrangements are disposed in generally opposite sides of the access shaft when viewed in plan so that in overall operation the liner pipe is moved into the pipework in a "zig zag" fashion in the same generally vertical plane.
11. Apparatus as claimed in Claim 10 wherein the rolls at the upper and lower parts of the access shaft are arranged to provide cross-section deformations of opposite sense.
12. Apparatus as claimed in Claim 10 or 11 in which a further roll arrangement is located in the access shaft between the upper and lower deforming roll arrangements for guidance purposes and assistance in removal of the distortion produced by the first roll arrangement.
13. Apparatus as claimed in any one of Claims 7 to 12 wherein an additional roll arrangement is provided adjacent to the entrance to the pipework at the lower end of the access shaft in succession to the lower deforming roll arrangement, said additional roll arrangement being adapted to act upon the side walls of the liner pipe and assist in the reversion thereof to its original pipe shape configuration.
14. Apparatus for relining underground pipework substantially as shown in and as hereinbefore described with reference to the accompanying drawings.