WO1999019659A1

WO1999019659A1 - Multi-layered renovative pipeliner

Info

Publication number: WO1999019659A1
Application number: PCT/GB1998/003014
Authority: WO
Inventors: David Andrews
Original assignee: Texon Uk Limited; Texon Materiales, S.L.
Priority date: 1997-10-10
Filing date: 1998-10-09
Publication date: 1999-04-22
Also published as: AU9546898A; GB9721405D0

Abstract

A pipeliner comprising a plurality of concentric tubes of fabric arranged to be receptive to curable resin, said tubes of fabric being coupled together with discontinuous adhesive means.

Description

MULTI-LAYERED RENOVATIVE PIPELINER

Technical Field

The present invention relates to multi-layered pipeliner and, more particularly, to pipeliner used to renovate sewerage pipes.

Background Art

It will be appreciated that the sewerage pipe network installed in most countries in the 19th century is now becoming elderly and therefore in need of replacement or renovation. Obviously, replacement of a sewerage pipe network will be expensive, time consuming and extremely inconvenient within the environs of a typical urban conurbation. Thus, the preferred approach is to renovate a sewerage pipe prior to collapse or other terminal condition. There are many ways of renovating a sewerage pipe but the technique which is the subject of the present invention involves use of a laminated fabric impregnated with a curable resin.

Typically, the fabric will be a non- woven felt laminated with a barrier layer formed from polyurethane or Surlyn plastics material. The fabric will be impregnated with a resin which is curable either after mixing with an activator compound, and/or as a result of conditioning at elevated temperature.

Once hardened, the resin impregnated into the fabric provides a robust reinforcing structure for the sewerage pipe and the barrier layer achieves an additional environmental seal for that sewerage pipe. Typically, a pipeliner is made from a sheet of non- woven felt laminated with a barrier layer and with longitudinal edges of the felt bonded together and sealed with a sealing tape in order to provide a continuous barrier around the complete circumference of the pipeliner tube.

Although a single pipeliner tube may be used to renovate a sewerage pipe of relatively low dimension, it is common in larger- dimension sewerage pipes for a combination of concentrically arranged pipeliner tubes to be assembled in order to achieve the necessary gauge for adequate reinforcement for renovation of the sewerage pipe. It will be appreciated that there is a limit to the thickness of non-woven felt that can be readily achieved with the necessary density to accommodate the curable resin. Thus, the gauge to create a sufficiently thick pipeliner for robust renovation is most conveniently achieved by a combination of several layers of such felt tubes. However, as indicated above, these layers of felt are typically laminated with a barrier layer formed from polyurethane or Surlyn plastics materials. Furthermore, it is advantageous for the sealing tapes overlying the longitudinal bond of each pipeliner tube to be arranged at displaced radial positions in order that a labyrinthine seal path is generated and the inevitable bulging of such sealing tapes are not collective to create a distortional problem within the pipeliner.

Those skilled in the art will understand that the concentric laminated felt tubes of a pipeliner in accordance with such a construction must be secured together in order to resist twisting and ballooning during installation. Such installation will normally at least involve inflation of the pipeliner using a fluidic medium and may also involve inversion of the pipeliner in order to force the pipeliner into the sewerage pipe to be renovated. Both these operations are obviously quite violent and can result in severe shock to the pipeliner.

The known technique for fusing the concentric fabric bes together is to provide flame bonds between the fabric and the barrier layer. In order to create the flame bond, a portion of the barrier layer is heated until it achieves a softened or melted state and then the fabric is brought into abutment with that softened portion of the barrier layer in order to create a bond. Such flame bonding inherently pins the layers of fabric in a concentric pipeliner construction and cannot take sufficient account of differential expansion or growth between the barrier laminate and the felt.

Unfortunately, and inevitably, the pipeliner used to renovate a sewerage pipe will generally be slightly the wrong size. It will be understood that a sewerage pipe will both expand and contract during its lifetime as a result of various seismic, erosion and other factors. Thus, a notional sewerage pipe size on installation may vary appreciably over the years. Such variation will be significant within the context of variation in the expansion of the barrier layer and underlying non-woven fabric as a result of resin reagent and temperature factors.

As indicated above, the fabric will typically be impregnated with a curable resin. This resin will typically be of an organic nature and so may attack the plastics material of the barrier layer causing significant volumetric growth. However, the underlying non- woven fabric being of a more heterogeneous random nature may not expand to an equivalent extent and may, under certain circumstances, even slightly contract. Thus, there is a significant differential between the barrier layer and the underlying felt in terms of expansion. However, as indicated above, the flame bonds created between the concentric layers of non-woven felt robustly tack these concentric fabric tubes together creating distortion and stress within the pipeliner which, upon curing, will precipitate separation between the concentric fabric tubes and potential failure of the pipeliner. It will be understood that a failed renovative pipeliner may be as expensive, if not more so, to replace than the original sewerage pipe for renovation.

Another problem with swelling of the pipeliner is wrong sizing. If the pipeliner is too small then the sewerage pipe to be renovated will not be properly reinforced and may partially collapse upon the undersized renovative pipeliner within. However, over-sizing of the renovative pipeliner will result in wrinkling and potentially soft spots due to inadequate curing of the resin in these wrinkles. Ideally, the pipeliner should be slightly undersized to enable expansion as a result of the resin/ temperature effects under inflation of the pipeliner. Thus, the renovative pipeliner upon installation will be slightly stretched and held in that stretched configuration by the cured resin held within the fabric of the pipeliner. Unfortunately, the flame bonds between the concentric laminated fabric layers of the pipeliner described above inhibit such marginal stretching to the desired pipeliner size.

It is an object of the present invention to provide an improved renovative pipeliner construction, especially one which substantially alleviates the above mentioned problems arising from flame bonding. It is also an object of the present invention to provide a method of making such a pipeliner.

Summary of the Invention

In accordance with the present invention there is provided a pipeliner comprising concentric mbes of fabric arranged to be receptive of curable resin, said mbes of fabric preferably including at least one barrier layer of plastics material, said mbes of fabric being coupled together with discontinuous adhesive means.

Said mbes of fabric may be arranged in their concentric configuration with said barrier layer, where present, there between.

Preferably, the discontinuous adhesive means is flexible to allow limited controlled shear movement between respective fabric mbes.

Preferably, the discontinuous adhesive means is affected by said curable resin in order to reduce the strength of coupling or remove such coupling in order to accommodate variable expansion of said fabric mbes and barrier layer.

The barrier layer may be formed from a polyurethane or Surlyn film laminated to the fabric tube. The fabric of the fabric mbes may be a non-woven textile fibre fabric or felt appropriately mechanically entangled to achieve a suitable density for pipeliner renovation and conveniently this felt may be made from polyester fibres. The curable resin with which the pipeliner is impregnated in use may be styrene based.

The discontinuous adhesive means may be applied randomly or regularly, for example in dots or stripes or bands. Where the adhesive means is applied randomly it may be applied in powder form, or in any convenient discontinuous form, by any suitable means for example electrostatic spraying, or as a random web of adhesive. Where the adhesive means is applied in a regular pattern, any suitable means of application may be used; for example known printing techniques including printing using an appropriately patterned roll or platen of a press or screen printing, or by using a stencil. The means of application will be selected according to the physical form of the adhesive means which may be fluid (with the adhesive component carried in solution or a water-based or solvent-based dispersion, or as a hot melt) or supplied as a powder. When supplied in hot-melt powder adhesive form the powder may be dispensed onto a sheet of fabric through a suitably patterned device so that the powder is deposited in the required pattern and it may be necessary to effect a preliminary activation of the powder adhesive to retain it in the desired pattern before assembling sheets of fabric together to form concentric mbes.

Conveniently, the continuous adhesive means is a hot-melt powder adhesive having a melting point below 65 °C.

Further, in accordance with the present invention, there is provided a method of making a pipeliner comprising: (a) procuring a sheet of fabric and applying a discontinuous pattern of adhesive to at least one surface of that fabric;

(b) assembling several sheets of fabric together, including at least one sheet of fabric processed in accordance with step (a) above, whereby respective longitudinal edges of each sheet of fabric are brought into juxtaposed position within a concentric configuration;

(c) securing said sheets of fabric together to provide a plurality of concentric mbes;

(d) propagating and facilitating said pattern of adhesive to couple respective sheets of fabric together through use of compression, heat or any other appropriate means.

In a method of making a pipeliner in accordance with the invention other means facilitating coupling sheets of fabric together may include activation reagents arranged to activate the adhesive.

In a method in accordance with the invention only one of the sheets of fabric may have discontinuous pattern of adhesive applied to it and the adhesive may be chosen to be capable of penetrating one or more adjacent sheets whereby to couple all of those sheets together.

In another method in accordance with the invention a discontinuous pattern of adhesive may be applied to all or most, of the sheets of fabric and each deposited pattern may be such as to only couple the sheet on which it is deposited to the next adjacent sheet. In carrying out a preferred method of making a pipeliner in accordance with the invention it is preferable to secure said longitudinal edges of each sheet of fabric together by stitching, welding or adhesive bonding to provide each concentric tube and provide sufficient strength to the pipeliner as well as to effect a good seal. However, although it is strongly preferred to ensure that the longitudinal edges of each sheet abut one another it may be possible to dispense with specific, dedicated, means to secure said longitudinal edges together and to rely on the discontinuous adhesive means to effect securement of the sheets of fabric together and retain said longitudinal edges in substantial abutment. In that event it is preferable to ensure that the longitudinal edges of each sheet are circumferentially displaced from the longitudinal edges of the next adjacent sheets with the adjacent edges of the various sheets equally spaced circumferentially around the pipeliner. Furthermore, the adhesive means may be applied selectively in order to achieve controlled variation of the coupled strength between the fabric tube layers over time and so facilitate twist correction or achieve a degree of cross fabric tube stress for greater renovation strength.

A pipeliner in accordance with the invention may be used in known methods of renovation which involve impregnating the pipeliner fabric with curable resin, introducing the pipeliner into a pipeline to be renovated, using known techniques, inflating the pipeliner to expand it into and maintain it in engagement with the interior of the pipeline to be renovated and curing or allowing curing of the curable resin to provide a rigid impervious liner within the pipeline. The curable resin may alter, over time, the adhesive in terms of the strength of the bond which couples respective sheets of fabric together.

The invention may also be considered to provide a method according to any one of claims 14 to 21 wherein the adhesive is polyester based.

Preferably in a method of installing a pipeliner in accordance with the invention the adhesive means is affected by the curable resin in order to reduce or remove the coupling between the fabric mbes during installation in the pipeline.

Brief Description of the Drawings

Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which Figure 1 is a schematic crosssection of a pipeliner and Figure 2-7 are a schematic plan view showing examples of discontinuous adhesive patterns.

Modes of Carrying out the Invention

The present invention relates to pipeliners used for renovation of sewerage pipes. As indicated above, with larger diameter pipelines it is necessary, in order to provide a sufficient gauge of fabric for adequate reinforcement in association with a curable resin, for several layers of non- woven textile fibre fabric or felt to be combined. Thus, as depicted in Figure 1 , several mbes of fabric are arranged in a concentric configuration. In Figure 1 , three mbes (1), (2), (3) are illustrated. However, it will be appreciated that more or less mbes could be used depending upon the performance required. These mbes (1), (2), (3) are formed by bringing longitudinal edges into a juxtaposed position and then securing these edges together to form a respective longitudinal bond (4), (5), (6) for each fabric mbe (1), (2), (3). In the preferred embodiment which is shown in Figure 1 only an outer mbe (3) has a laminated barrier layer (7) which provides an environmental seal for the pipeliner, in use. However, it will be appreciated that the other mbes (2), (3) could also be laminated with a barrier layer. Any suitable barrier layer can be used; the barrier layer is conveniently a plastics material, generally a polyurethane or a Surlyn plastics material of appropriate thickness to provide resilience within a renovative pipeliner environment.

In order to ensure the pipeliner (10) formed by the mbes (1), (2), (3) remains assembled with the mbes in desired relative positions, it is necessary to couple these respective mbes together. Previously, this was done using flame bonds between the surfaces of respective mbes (1), (2), (3) in abutment. Unfortunately, flame bonds are rigid and thus inappropriate for accommodation of the inherent expansion variations between the respective mbes (1), (2), (3) and also the component fabric and barrier layer of these respective mbes (1), (2), (3). Thus, distortion and stress are an inherent problem. Furthermore, such flame bonds inhibit stretch expansion of the pipeliner (10) upon installation. Ideally, the pipeliner should be slightly, i.e. about 5 % , undersized with regard to the sewerage pipe to be renovated, and the pipeliner under the inflationary effect of a calibration mbe will expand into the diameter of the sewerage pipe. It will be appreciated that preferred barrier layer materials, for example polyurethane and Surlyn, are quite elastic and that the fabric of the mbes (1), (2), (3) is generally a non- woven felt which can stretch to a degree. In use, the curable resin held within the non-woven fabric will, upon curing, consolidate the pipeliner (10) in its stretched configuration within the sewerage pipe to be renovated. It will also be understood by those skilled in the art that the curable resin impregnated into the pipeliner (10) may have an effect upon the barrier layer in increasing the flaccidity of such layer and so allowing greater expansion. Generally, the flame bonds inhibit such expansion by providing resilient fixed tacks between the mbes (1), (2), (3) in previous pipeliner constructions.

In accordance with the present invention, flame bonds between the mbes (1), (2), (3) are eliminated and replaced with discontinuous adhesive bonds spread about the respective surfaces (8), (9) between the mbes (1), (2), (3). The adhesive used will generally be degradable under the effect of the curable resin impregnated into the pipeliner (10). An example of a suitable adhesive is the powder adhesive Bostik Esterpow (a 50/50 blend of 1112 AF and 1108 AF adhesive components). This powder adhesive is polyester based, believed to comprise poly (tetramethylene-adipate), has a relatively low melting point and has a crystallinity melt temperature of 55- 60°C. Powder adhesives have an advantage in that they can be readily applied in an appropriate pattern upon a fabric such as a non-woven felt or a barrier layer formed from polyurethane or Surlyn.

An important feature of a preferred embodiment of the present invention is that the discontinuous adhesive pattern applied to the surfaces (8), (9) can be controllable or at least predictable within certain parameters. Thus, the pipeliner installer can control the strength of the coupling bond between the respective mbes (1), (2), (3) in operation in light of the prevailing requirements and circumstances. Thus, the pipeliner installer will know from appropriate look-up data the effect of the curable resin which is being used in a particular installation upon the pipeliner construction in terms of expansion, the respective rate of degradation and strength of the coupling bond at surfaces (8), (9) along with installation details such as the respective undersizing of the pipeliner with regard to the sewerage pipe to be renovated and the inflation pressure created by the inflation fluid within the calibration mbe upon installation. In such circumstances, the installer will be able to calculate the time window within which installation must take place in order to create the best renovative conditions. Such time window will be dependent upon the degree of expansion necessary of the pipeliner as a result of undersizing and whether such expansion necessitates the complete breakaway of the adhesive coupling bond at surfaces (8), (9) or merely an appropriate loosening of such bond, etc. It will be appreciated that bonding between fabric and barrier layer will have a different effect in comparison with bonding between two fabric surfaces for many reasons, including the inherent difference in adhesive penetration depth into the respective mbe (1), (2), (3). It will be appreciated by those skilled in the art that the adhesive when applied to a fabric will penetrate beyond the fabric surface whilst adhesive applied to the barrier layer will not generally penetrate that layer.

The method of making the pipeliner (10) is known to those skilled in the art, except that prior to forming the pipeliner (10) a discontinuous pattern of adhesive is applied to the sheet of fabric from which each fabric mbe is formed. The particular pattern and extent of adhesive deposition is determined by performance requirements and the adhesive used. Furthermore, the principal types of adhesive, i.e. solvent based, water based, or hot melt adhesives have different aging performance. Thus, solvent based adhesives can be readily dissolved to degrade or break away the coupling bond between mbes (1), (2), (3). However, water based adhesives are very difficult, once dry, to degrade. In view of the above, it will be appreciated that the type of adhesive used should be determined by the manufacturer or pipeliner installer in order to achieve the best performance in the time frames expected between resin impregnation and installation. It will also be understood by those skilled in the art that different adhesive types or grades could be used at different zones or segments of the pipeliner in order to give differential performance and so create stressing which could be preferential to reinforcing within a sewerage pipe, to be renovated. For example, if there is a degree of cross-plying with regard to stress in adjacent fabric mbe layers then the radial and/or longitudinal strength of the pipeliner could be altered in a similar fashion to cross-ply vehicle tyres. Finally, such differentials between adhesive patterns with regard to patterns and type/grade could be made in respective layers at interface surfaces (8), (9) in order to control the degree of expansion or to create a pseudo peristaltic waved surface for the pipeliner upon curing.

As indicated above, the discontinuous adhesive pattern applied to the fabric mbe surface to a large extent determines performance in association with the particular adhesive used. In Figures 2-7 some examples are depicted of appropriate adhesive patterns. Figure 2 illustrates a random dot or spot application of adhesive. It will be appreciated that random application of adhesive spots ensures that the coupling bond performance is not orientationally dependent and is generally equalised in all planes.

Figure 3 illustrates dots in a regular but evenly distributed pattern. Again, such a pattern should be substantially equalised in all planes but it is important that the spacing of the dots/spots of adhesive is close enough to achieve necessary bond strength, as compared to the random pattern shown in Figure 1 ; it will be appreciated that a lower level of adhesive dot density should be necessary to achieve the same result but at the risk, if badly applied, of the coupling bond strength being insufficient. An example of such bad application would be if there were dry or reduced adhesive deposition areas within the pattern.

Figures 4 and 5 illustrate respectively discontinuous and continuous spaced stripes of adhesive as discontinuous adhesive patterns in accordance with the present invention. It will be appreciated that the stripes could be as depicted about the circumference of the pipeliner or be orientated in the axial direction of the pipeliner. Furthermore, the provision of circumferential stripes or longitudinal stripes will give differing coupling bond performance in respective radial and longitudinal directions of the pipeliner. The width and spacing of the stripes may be regular or varied in order to provide a desired performance.

In Figure 6 alternative adhesive pattern elements are illustrated including circles, discs and crosses. It will again be appreciated that use of different deposition elements will alter coupling bond performance. Alternatives include concentric rings of adhesive, squares, diamonds, etc.

In Figure 7 it can be seen that combinations of stripes which are continuous, variously spaced, and/or discontinuous can be created in the same pattern dependent upon desired performance. Furthermore, as indicated above, a pipeliner embodying the invention may have different patterns of adhesive at different zones or segments of the pipeliner. For example, it may be possible to combine at a first fabric mbe interface, e.g. (9) in Figure 1 , radial stripes with a second discontinuous adhesive pattern at a further fabric mbe interface (8) with longitudinal stripes such that in combination the securing strength is compounded to achieve the necessary performance.

As indicated previously, it is desirable when specifying a pipeliner for renovation purposes that the pipeliner is slightly undersized and allowed to expand into the actual sewerage pipe dimensions. Thus, a 5% differential can be achieved. In accordance with the present invention it is desirable that there is a fabric to fabric, i.e. felt to felt, bond rather than a more traditional barrier layer to felt flame bond described. Such felt to felt bonding using adhesive is more convenient due to the consistency of the surfaces to be bonded in comparison with previous barrier layer to fabric differences.

Once cured, it will be appreciated that the resin held within the fabric of the pipeliner (10) provides the essential integral combination of the respective concentric fabric mbes (1), (2), (3). Thus, the discontinuous adhesive pattern can be relatively sacrificial in that its primary objective is to hold the fabric mbes (1), (2), (3) together during manufacture and installation but once cured the adhesive becomes relatively incidental to such pipeliner (10) integrity. In such circumstances the degradation of the adhesive by the curable resin is acceptable and in accordance with a preferred embodiment the present invention is utilised as an approach to provide more specific performance control of the pipeliner in use with regard to reinforcement and tailoring within the pipe to be renovated. Furthermore, by use of the flexibility inherent in an adhesive, the pipeliner (10) embodying the present invention is more flexible with regard to accommodation of the stresses of installation in comparison with the relatively brittle coupling bonding achieved by flame bonds in accordance with prior knowledge.

Moreover, the use of a discontinuous adhesive pattern permits penetration of curable resin when the pipeliner is being impregnated throughout the plurality of fabric layers, facilitating uniform distribution of the resin throughout the pipeliner and contributing to predictable performance.

Typically, the fabric from which the fabric mbes are formed will generally have a gauge of several millimetres, e.g. 2-8mm preferably about 6mm and the barrier layer will be approximately 1 millimetre thick. However, it will be understood that the thickness is determined by the necessary assurance that the barrier layer will not be abraded away during installation against the sewerage pipe wall surface. The mbe will be made by bringing longitudinal edges of a fabric sheet together and securing these edges together with a weld or adhesive or stitching. Furthermore, it will be common for the longitudinal bond (6), at least at the outer surface of the pipeliner (10), to be sealed with a sealing tape to provide a complete circumferential barrier. This sealing tape will be secured to the barrier layer (7) using an adhesive. As depicted in Figure 1 in order to create a labyrinthine combination, the longitudinal bonds (4), (5), (6) of the pipeliner (10) may be spaced about the pipeliner circumference. Thus, in the three mbe pipeliner depicted in Figure 1 , the longitudinal bonds (4), (5), (6) are equally spaced, located at approximately 120° spacings with respect to each other. A further advantage with such equal spacing when each longitudinal bond (4), (5), (6) has a sealing tape is that the distortional effects of the bond (4), (5), (6) and the tape are distributed about the pipeliner (10) rather than accumulative at one point on the circumference of the pipeliner (10).

Typically, the curable resin will be styrene based and such a curable resin will affect a polyester adhesive eg poly (tetramethylene- adipate) mentioned above, tending to cause the bond to weaken. It has also been found that such a styrene-based resin affects polyurethane barrier layer material. However, it will be appreciated that other resin types could be used with differing degrees of effect upon the barrier layer, discontinuous adhesive pattern and fabric felt. Furthermore, provided there are no detrimental effects to the curing performance of the resin, it will be appreciated that the resin could incorporate activating reagents for the degradation of the adhesive and also precipitate enhanced or reduced expansion of the fabric mbe including the barrier layer. Such reagent included in the curable resin could be arranged to precipitate a colour change in the adhesive such that when the discontinuous adhesive pattern is applied as a stripe, distortions in that stripe can be seen, i.e. if the stripe became bright orange it could be seen through the substantially clear resin and any distortions from the straight stripe could be seen. Furthermore, with a little more sophistication, such colour change in the adhesive could be used to denote areas of excessive shear slippage between the respective layers of fabric mbe, as such slippage would appear as a broad smudge due to the localised relatively large movements of the respective mbe layers resulting in spreading of the adhesive.

Those skilled in the art will appreciate that there are alternative embodiments to the present invention which are not described above but should be incorporated within the scope of the present application.

Claims

1. A pipeliner comprising a plurality of concentric mbes of fabric arranged to be receptive to curable resin, said mbes of fabric being coupled together with discontinuous adhesive means.

2. A pipeliner according to claim 1 also comprising at least one barrier layer of plastics material laminated with at least one of the fabric mbes.

3. A pipeliner according to claim 2 wherein the barrier layer is laminated with the outer fabric mbe on an outer surface thereof to provide an environmental seal.

4. A pipeliner according to any one of the preceding claims wherein the fabric is a non- woven fibre fabric.

5. A pipeliner according to any one of the preceding claims wherein the adhesive means is flexible to allow limited shear movement between the fabric layers of adjacent mbes.

6. A pipeliner according to any one of the preceding claims wherein the adhesive means is such that it is affected by said curable resin or a component thereof, to reduce the strength of or to remove such coupling between the concentric mbes.

7. A pipeliner according to any one of the preceding claims wherein the adhesive means is in a random pattern.

8. A pipeliner according to any one of claims 1 to 6 wherein the adhesive means is in a regular pattern.

9. A pipeliner according to claim 8 wherein the pattern is made up of dots, stripes or bands or any combination of same.

10. A pipeliner according to any one of the preceding claims wherein the adhesive means is such as to provide controlled variation of the coupled strength between the fabric mbes over a period of time.

11. A pipeliner according to any one of the preceding claims comprising different patterns of adhesive at different zones or segments of the pipeliner.

12. A pipeliner according to any one of the preceding claims wherein the adhesive means comprises poly (tetramethylene-adipate).

13. A pipeliner according to any one of the preceding claims wherein the adhesive means comprises a regular pattern and includes means whereby the pattern can be made visible during installation of the pipeliner whereby distortions or changes in the pattern can be monitored and may indicate degree of effectiveness of installation of the pipeliner.

14. A method of making a pipeliner comprising:

(a) procuring a sheet of fabric and applying a discontinuous pattern of adhesive to at least one surface of that fabric; (b) assembling several sheets of fabric together, including at least one sheet of fabric processed in accordance with step (a) above, whereby respective longimdinal edges of each sheet of fabric are brought into juxtaposed position within a concentric configuration;

15. A method according to claim 4 wherein said longimdinal edges of each sheet are secured together in substantially abutting relation.

16. A method according to claim 15 comprising applying a longitudinally extending sealing tape to seal the region between the longimdinal edges.

17. A method according to either one of claims 14 and 15 wherein the fabric is a non- woven fibre fabric.

18. A method according to any one of claims 14 to 17 wherein the adhesive is applied in a random pattern.

19. A method according to any one of claims 14 to 17 wherein the adhesive is applied in a regular pattern, for example by printing.

20. A method according to any one of claims 14 to 19 wherein the adjacent longimdinal edges of each sheet of fabric are spaced from the adjacent edges of the other sheets of fabric about the pipeliner circumference.

21. A method according to any one of claims 14 to 20 wherein the adhesive has a low melting point, below 65 ┬░C.

22. A method according to any one of claims 14 to 21 wherein the adhesive is polyester based.

23. A method according to any one of claims 14 to 22 wherein the adhesive is applied to the fabric in powder form.

24. A method of installing a pipeliner accordmg to any one of claims 1 to 13 comprising impregnating the pipeliner fabric with a curable resin introducing the pipeliner into a pipeline to be renovated, inflating the pipeliner to expand it into engagement with the pipeline, and curing or allowing curing of the curable resin to provide a liner within the pipeline.

25. A method according to claim 22 wherein the adhesive means is affected by the curable resin in order to reduce or remove coupling between the fabric mbes during installation in the pipeline.