WO1992006323A1

WO1992006323A1 - Improvements in or relating to conduit lining layers

Info

Publication number: WO1992006323A1
Application number: PCT/GB1990/001491
Authority: WO
Inventors: Gerard Francis Burns
Original assignee: W.E. Rawson Limited
Priority date: 1990-09-28
Filing date: 1990-09-28
Publication date: 1992-04-16

Abstract

A hose (14) is extended through the inner wall of a pipe (10) to be repaired and hydraulic pressure is exerted such that the hose is biased against the inwardly facing surface of the pipe (10) and at least partially into a space from which leads a branch pipe (26). The hose (14) is more readily able to expand in the circumferential direction with respect to the pipe (10) than it is in t he longitudinal extent of the pipe (10) and thereby the hose (14) extends a considerable extent into the opening leading to the branch pipe (26). After the hose (14) has been placed in position and the resin which it contains has undergone an exothermic reaction to harden, a camera is passed within the main pipe (10) and when the depression of the hose at the opening to the pipe (26) is viewed, at least a part of that depression is removed in order to gain access to the branch pipe (26).

Description

IMPROVEMENTS IN OR RELATING TO,CONDUIT LINING LAYERS

The present invention relates to conduit lining layers, a method of impregnating a conduit lining layer, a method of forming a conduit lining layer, methods of lining conduit and lined conduits.

In a known method of lining pipes having a duct leading from the pipe, a flexible resin coated layer is layed along the inside of the pipe and held against the inwardly facing surface of the pipe and over the duct by hydrostatic pressure. The layer must be resistant to elongation along the pipes if it is not to stretch thinly and unevenly along the pipe thereby reducing its thickness and ultimate strength. The resin is hardened by heating the water which exerts the hydrostatic pressure to cause the resin to undergo an exothermic reaction and thereby harden. The portion of the hardened layer extending over the opening to the duct leading from the lined pipe then has to be removed. This is achieved by passing a camera within the pipe and attempting to locate the opening by detecting a difference in shape of the lining at the opening and then cutting out a portion of the lined layer. However, as the layer must be strong to resist the hydrostatic forces tending to stretch the layer along the pipe, and as the pipe being lined is being repaired and may have an uneven surface and as the working conditions are dim and dirty, it is extremely difficult to locate any difference in the shape of the lining at the opening to the duct. Consequently valuable time is lost in searching for the opening and an incorrect portion of the lining may be attempted to be removed in the mistaken belief that it covers the duct opening, thereby ruining the new liners. An additional problem with the layers is that in order to achieve their strength, the fibres making up the layers must be fairly compact thereby reducing the amount of resin which a given length can hold and thereby necessarily limiting the thickness and strength of the new lining. Furthermore, the resin takes a considerable time to penetrate the layer because of the necessary high density of fibres thereby not only resulting in a long production time but also endangering the layer as the resin is prone to commencing its exothermic reaction if time is taken to impregnate the layer, and such a reaction during impregnation ruins the layer.

It is an object of the present invention to attempt to overcome at least some of the above disadvantages.

According to one aspect of the present invention a conduit lining layer is arranged, in use, to be located within and around a conduit in which the material comprising the layer includes fibres with the density of the fibres of the layer extending at an angle to the general extent of the layer being greater in a first direction in which, in use, the layer is arranged to extend around a conduit than the density of fibres extending at an angle to the general extent of the layer, which fibres extend in a second direction in which, in use, the layer is arranged to extend along a conduit. Such a conduit lining layer may be particularly useful where it is lining a conduit having one or more openings leading therefrom as the second direction of the layer can be arranged to coincide with the longitudinal axis of the conduit whereby the layer does not expand unduly along the length of the conduit as the layer is being located in position and when the layer is under pressure and yet the layer is able to expand into the opening leading from the conduit as a result of a pressure differential being created across the layer in order that the opening can be easily determined by virtue of the significant depression in the lining at the location of the opening when the lining is being inspected from within the conduit.

The layer may be endless when viewed in one cross- sectional view, and may be tubular.

The ratio of the ability to expand in the first direction relative to the second direction may be equal to or less than 3:1 and may be in the region of 2:1 and is preferably substantially 3.05:1.65.

The Youngs Modulus for the layer in the first direction may be equal to or less than 3N/mm and may be in the region of 1.65N/mm. The Youngs Modulus for the layer in the second direction may be equal to or less than 5N/mm and may be substantially 3N/mm.

Tne layer may include an internal region or regions of less density than outer regions. The internal region or regions may extend in the general direction of the second direction. The internal region or regions may be defined at least in part by a ceiling layer, or alternatively the internal region or regions may be defined by fibres.

The layer may be impregnated with a hardenable fluid.

One or both of the surfaces of the layer may be sealed, for instance by a further layer or layers.

A greater number of fibres may extend in the first direction than in the second direction. According to a further aspect of the present invention a method of forming a conduit lining layer comprises reorientating fibres in a layer such that the density of fibres extending at an angle of the general extent of the layer is greater in a first direction than the density of fibres extending at an angle to the general extent of the layer in a second direction transverse to the first direction.

The fibres may be reorientated such that a greater number of fibres extend in the first direction than in the second direction.

The fibres may be reorientated from a layer having fibres located randomly.

The method may comprise creating a region of reduced fibre density within the layer between those displaced fibres and other fibres.

Fibres may be displaced from the general extent of the layer with the displaced fibres extending generally in the first direction, when viewed from the side of the laye .

Fibres may be reorientated to extend generally in the first direction when viewed from the side of the layer.

A region of reduced fibres density may be created.

The method may comprise reorientating fibres by causing relative movement between the layer and a member having a notch extending in the second direction such that the notch passes relative_ to the fabric from one side towards the other side. Passing the notch relative to the fabric from one side towards the other side may reorientate fibres to extend generally in the first direction when viewed from the side of the layer.

The region of reduced density may extend generally in the second direction.

The method may further comprise impregnating the layer with a hardenable liquid. At least some of the liquid may impregnate the layer from within the layer. The liquid may be caused to occupy the region of reduced fibre density. The hardenable liquid may be caused to move along the region of reduced density during impregnation.

The method may comprise forming the layer into an endless layer, when viewed from one direction.

The method may comprise sealing one side of the layer, for instance with a sealing layer. The sealing layer may define part of the region of reduced density.

The present invention also includes a conduit which has been lined by a layer as herein referred to, or which has been lined by a layer which has been made by a method as herein referred to.

According to another aspect of the present invention a method of lining a conduit having an opening leading therefrom comprises locating a layer in the region of an inner surface of the conduit, with the layer extending across the opening, creating a pressure differential across the layer to cause the layer to extend at least partially into the opening, with the layer having less resistance to expansion in the direction transverse to the longitudinal extent of the conduit than in the direction of the longitudinal extent of the conduit, and removing at least a part of the layer extending across the opening.

The method may comprise viewing the internal region of the conduit and determining from that viewing where the layer extends at least partially into the opening prior to removing at least a part of the layer extending across the opening.

According to a further aspect of the present invention a method of lining a conduit using a lining layer impregnated with hardenable liquid in which the layer includes internal regions of less density than outer regions, the internal regions extending in the longitudinal extent of the conduit with those internal regions including hardenable resin comprises exerting an outwards force on the layer and causing the hardenable liquid in those internal regions to spread outwardly towards adjacent internal regions of less density.

The method may comprise the layer having less resistance to expansion in the direction transverse to the longitudinal extent of the conduit than in the direction of the longitudinal extent of the conduit. The method may further comprise an opening and a layer extending across the opening with a pressure differential being created across the layer to cause the layer to extend at least partially into the opening with at least a part of the layer extending across the opening subsequently being removed.

The present invention also includes a conduit when lined by a method as herein referred to. The present invention also includes a method of impregnating a conduit lining layer with a hardenable liquid in which the layer includes internal regions of less density extending in a generally common direction comprising causing at least some of the liquid to enter the regions of less density.

The method may comprise causing at least some of the liquid to travel along the regions of less density during impregnation.

The method may comprise causing at least some of the liquid to travel from regions of less density into other regions of the layer.

The method may comprise passing the layer through a restricted region during impregnation.

The method may comprise forming the layer into a tube and locating liquid initially in space within the tube prior to, or during impregnation. The method may comprise surrounding the tube by a further layer resistant to the passage of liquid.

The present invention also includes a conduit lining layer which has been impregnated by a method as herein referred to.

The present invention includes any combination of the herein referred to features.

The present invention may be carried into practice in various ways, but one embodiment will now be described by way of example and with reference to the accompanying drawings, in which:- Figure 1 is a schematic cross-section through part of a pipe being lined;

Figure 2 is a section taken along the line II-II of Figure 1;

Figure 3 is a schematic plan view of a piece of felt, prior to processing, for use in lining a pipe, and

Figure 4 is a schematic perspective view of the felt in Figure 3 after that felt has been processed.

A pipe 10 is shown in Figures 1 and 2 which is to be realigned in order to seal cracks 12 or other faults in the pipe wall. The pipe is lined with a tubular hose 14 comprising an outer sealing layer 16, which lies against the inwardly facing surface of the pipe, and an inner felt layer 18 which is impregnated with resin.

In order to repair a pipe and reline it with the hose 14 the hose is inserted into an open end of the pipe with a part of the sealing layer 16 against the internal wall of the pipe and with the majority of the tube having been turned back on itself such that it passes back out of the pipe. Water is then located in the space 20 defined by the opposing surfaces of the felt and the hose is caused to advance in the direction of arrow 22 as a result of the water pressure acting on the interior of the forward end of the base. The water pressure may be derived from a head of water or from a pump.

When the hose has extended along the required length of pipe the water in the pipe is then heated and the resin in the felt 18 undergoes an exothermic reaction to cause the resin to polymerise and harden and thereby reline the pipe with a sealed self supporting layer.

A branch pipe 26 extends away from the downwards side of the main pipe 10 and the hose 14 must be removed from the opening to that pipe if the repaired pipe is to be placed in communication again with the branch pipe. The portion of hose to be removed is located by passing a camera within the relined but vacant pipe 10 until a depression 28 caused by the hose extending outwardly into the branch pipes is seen by the camera, whereupon remotely operated cutting apparatus can cut out the hose to open up the passage to the branch pipe 26. Furthermore, as the felt has expanded in the region of the depression the thickness of resin there will be less than the thickness adjacent to the inner wall of the pipe thereby facilitating removal of the depression.

It will be appreciated that the felt must not stretch unduly in the axial direction of the pipe 10 as otherwise its thickness in the pipe and therefore its strength will decrease. However, in order for the depression 28 to be readily detectable by the camera it is αesirable that the felt stretch as much as possible. This dichotomy is resolved by making the felt more readily expandable in the circumferential direction of the pipe than it is in the axial direction in a manner to be described below in relation to Figures 3 and 4.

The felt 18 is processed prior to impregnation with the resin as follows. The felt shown in Figure 3 comprises randomly arranged fibres. That felt is passed over a grid comprised by upwardly extending parallel plates, and needles are passed down to push some of the fibres downwardly between the plates before the needles are retracted. The needles comprise flat plates parallel to the grid plates which include a small notch transverse to the grid plates, which notch engages and pushes fibres extending in the general weft direction and also reorientates other fibres more towards or generally in the weft direction. That process results in the fibre shown in Figure 4 in which the warp fibres 30, in use, extend along the axis of the pipe but the weft fibres are arranged to extend circumferentially around the pipe. The weft fibres are made up of straight or arc shaped fibres 32 which have been pushed by the needles such that they do not extend in the general extent across the layer and substantially flat fibres 34 which extend across the felt.

The warp threads 30 and the flat fibres 34 may form the base of tunnels 36 which run in the warp direction of the felt with the upper part of those tunnels being defined by the straight or arc shaped fibres 32. It will be appreciated that the felt is shown very much in schematic form for ease of understanding and that the fibres will not all lie in the exact configurations shown. Furthermore, the tunnels 36 are not devoid of fibres but comprise a much less dense region of fibres where the needles have been pushed through.

Alternatively the fabric may have less dense regions, running in the warp direction which are bounded on one side by the sealing layer 16.

The ratio of warp threads 30 to the flat weft threads 34 is approximately 24 to 8 or 9 and accordingly the felt is able to expand much more readily in the circumferential direction, when it is mounted in the pipe, than it is in the axial direction as a result of the fibres 32 being brought back into line with the general extent •of the fibre. The arrangement of the threads in the felt also results in a Young's Modulus, in the warp direction, of 3.05 N/mm² and, in the weft direction, of 1.65 N/mm2.

After the felt has been made into the form shown in Figure 4, a polyurethane coating comprising the sealing layer 16 is applied on to the opposite side of the felt from that which the tunnels 36 are formed on, and the material is brought round to form a tube with the layer 16 lying outermost. The polyurethane coating or the felt or both are then stitched or sealed together.

Resin is then inserted into the tube and the tube is passed through rollers in order to squeeze the resin into the felt and saturate the felt with the resin. The presence of the tunnels 36 running longitudinally along the tube, combined with the relatively loose weft threads ensures rapid saturation of the felt both as a result of the easy penetration of the felt and as resin is ab^e to run along the tunnels and penetrate the surface regions of the felt from within. This feature is of importance as the polyester resin is exothermic and can tend to heat up during the impregnation process, particularly if the impregnation is not done rapidly. Accordingly, the rapid impregnation reduces the risk of the exothermic reaction of the resin occurring during impregnation. Furthermore, the rapid impregnation reduces the time required to process the tube from prior methods where impregnation is not so rapid. A further advantage of the tunnels 36 is that they are able to contain more rein than a felt which is more compact thereby increasing the thickness and strength of lining provided by hardening resin in the felt. When the tube is being progressed along a pipe, the hydrostatic pressure pushes the tunnels 36 outwardly and tends to collapse or depress the tunnels, at least partially, thereby squeezing the resin around the circumference to ensure an even distribution.

Claims

CLAIMS :

1. A conduit lining layer (14) arranged, in use, to be located within and around a conduit in which the material comprising the layer includes fibres with the density of the fibres of the layer extending at an angle to the general extent of the layer being greater in a first direction in which, in use, the layer is arranged to extend around a conduit than the density of fibres extending at an angle to the general extent of the layer, which fibres extend in a second direction in which, in use, the layer is arranged to extend along a conduit.

2. A layer as claimed in Claim 1 which is endless in the first direction.

3. A layer as claimed in Claim 1 or 2 which is tubular.

4. A layer as claimed in any preceding claim in which the ratio of the ability to expand in the first direction relative to the second direction is equal to or less than 3:1.

5. A layer as claimed in Claim 4 in which the ratio is in the region of 2:1.

6. A layer as claimed in Claim 5 in which the ratio is substantially 3.05:1.65.

7. A layer as claimed in any preceding claim in which Youngs Modulus for the layer in the first direction is equal to or less than 3N/mm.

8. A layer as claimed in Claim 7 in which Youngs Modulus for the layer in the first direction is in the region of 1.65N/mm.

9. A layer as claimed in any preceding claim in which Youngs Modulus for the layer in the second direction is equal to or less than 5N/mm.

10. A layer as claimed in Claim 9 in which Youngs Modulus in the second direction is substantially 3N/mm.

11. A layer as claimed in any preceding claim including an internal region of less density than outer regions.

12. A layer as claimed in Claim 11 including internal regions of less density than outer regions.

13. A layer as claimed in Claim 11 or 12 in which the internal region or regions extend in the general direction of the second direction.

14. A layer as claimed in Claim 12 or 13 in which the internal region or regions are defined at least in part by sealing layer.

15. A layer as claimed in Claim 12 or 13 in which the internal region or regions are defined by fibres.

16. A layer as claimed in any preceding claim impregnated with a hardenable fluid.

17. A layer as claimed in any preceding claim in which one of the surfaces of the layer is sealed.

18. A layer as claimed in any of Claims l to 16 in which both surfaces of the layer are sealed.

19. A layer as claimed in any preceding claim in which a greater number of fibres extend in the first direction than in the second direction.

20. A method of forming a conduit lining layer comprising reorientating fibres (32) in a layer such that the density of fibres extending at an angle to the general extent of the layer is greater in a first direction than the density of fibres extending at an angle to the general extent of the layer in a second direction transverse to the first direction.

21. A method as claimed in Claim 20 in which the fibres are reorientated such that a greater number of fibres extend in the first direction than the second direction.

22. A method as claimed in Claim 20 or 21 in which the fibres are reorientated from a layer having fibres located randomly.

23. A method as claimed in any of Claims 20 to 22 in which fibres are displaced from the general extent of the layer with the displaced fibres extending generally in the first direction, when viewed from the side of the layer.

24. A method as claimed in any of Claims 20 to 22 comprising reorientating fibres to extend generally in the first direction when viewed from the side of the layer.

25. A method as claimed in any of Claims 20 to 24 comprising creating a region (36) of reduced fibre density.

26. A method as claimed in any of Claims 20 to 25 comprising reorientating fibres by causing relative movement between the layer and a member having a notch extending in the second direction such that the notch passes relative to the fabric from one side towards the other side.

27. A method as claimed in Claim 26 in which passing the notch relative to the fabric from one side towards the other side reorientates fibres to extend generally in the first direction when viewed from the side of the layer.

28. A method as claimed in Claim 25 or 26 or 27 when dependent on Claim 25 in which the region of reduced density extends generally in the second direction.

29. A method as claimed in any of Claims 20 to 28 comprising impregnating the layer with a hardenable liquid.

30. A method as claimed in Claim 29 comprising at least some of the liquid impregnating the layer from within the layer.

31. A method as claimed in Claim 29 or 30 when dependent upon Claim 22 in which the liquid is caused to occupy the region of reduced fibre density.

32. A method as claimed in Claims 31 in which hardenable liquid is caused to move along the region of reduced density during impregnation.

33. A method as claimed in any of Claims 20 to 32 comprising forming the layer into an endless layer, when viewed from one direction.

34. A method as claimed in any of Claims 20 to 33 comprising sealing one side of the layer.

35. A method as claimed in Claim 34 comprising sealing one side of the layer with a sealing layer.

36. A method as claimed in Claim 33 and 25 in which the sealing layer defines part of the region of reduced density.

37. A conduit which has been lined by a layer as claimed in any of Claims 1 to 19 or by a layer which has been made by a method as claimed in any of Claims 20 to 36.

38. A method of lining a conduit having an opening leading therefrom comprising locating a layer (18) in the region of an inner surface of the conduit with the layer extending across the opening, creating a pressure differential across the layer to cause the layer to extend at least partially into the opening witn the layer having less resistance to expansion in a direction transverse to the longitudinal extent of the conduit than in the direction of the longitudinal extent of the conduit, and removing at least a part of the layer extending across the opening.

39. A method as claimed in Claim 38 comprising viewing the internal region of the conduit and determining from that viewing where the layer extends at least partially into the opening prior to removing at least a part of the layer extending across the opening.

40. A method of lining a conduit using a lining layer (18) impregnated with hardenable liquid in which the layer includes internal regions (36) of less density than outer regions, the internal regions extending in the longitudinal extent of the conduit with those internal regions including hardenable resin comprising exerting an outwards force on the layer and causing the hardenable liquid in those regions to spread outwardly towards adjacent internal regions of less density.

41. A method as claimed in Claim 40 in which the layer has less resistance to expansion in the direction transverse to the longitudinal extent of the conduit than in the direction of the longitudinal extent of the conduit.

42. A method as claimed in Claim 40 or 41 in which the conduit includes an opening and the layer extends across the opening with a pressure differential being created across the layer to cause the layer to extend at least partially into the opening with at least a part of the layer extending across the opening subsequently being removed.

43. A conduit which has been lined by a method as claimed in Claim 38 or 39 or as claimed in Claims 40, 41 or 42.

44. A method of impregnating a conduit lining layer with a hardenable liquid in which the layer includes internal regions of less density extending in a generally common direction comprising causing at least some of the liquid to enter the regions of less density.

45. A method as claimed in Claim 44 comprising causing at least some of the liquid to travel along the regions of less density during impregnation.

46. A method as claimed in Claim 44 or 45 comprising causing at least some of the liquid to travel from regions of less density into other regions of the layer.

47. A method as claimed in any of Claims 44 to 46 comprising passing the layer through a restricted region during impregnation.

48. A method as claimed in any of Claims 44 to 47 in which the layer comprises a tube, and liquid is located initially in the space within the tube prior to, or during impregnation of the layer.

49. A method as claimed in Claim 48 in which the tube is surrounded by a further layer resistant to the passage of liquid.

50. A conduit lining layer which has been impregnated by a method as claimed in any of Claims 44 to 49.