AU4883102A - Guiding means for installation of formed-in-situ conduit repairs - Google Patents

Description

ORIGINAL

Australia Patents Act 1990 Complete Specification for the Invention Entitled GUIDING MEANS FOR INSTALLATION OF FORMED-IN-SITU CONDUIT REPAIRS The invention is described in the following statement: GUIDING MEANS FOR INSTALLATION OF FORMED-IN-SITU CONDUIT REPAIRS This invention relates to improvements in methods and apparatus for the installation of formed-in-situ repairs in pipes and conduits. In particular, it relates to methods in which suitably shaped, fibrous, woven or knitted repair material impregnated with a settable resin is carried into place within a pipe or conduit to be repaired by a progressively everting form, the everted part of which is kept in an inflated state to maintain said repair material in intimate contact with the inner surface of said pipe or conduit until said settable resin is cured' PCT Patent Application No. PCT/AU98/00988 teaches a method of installing a formned-in-situ repair in a pipe or conduit through the use of a progressively everting form to carry into place within said pipe or conduit resin-impregnated repair material. In this method, guiding means in the form of a guide .tape or cord passes.along and through the length of the uninverted part of said everting form and its distal end is led out the end of the section of said pipe or conduit to be repaired. Tension applied to said distal end of said guiding means acts to guide the everting zone of said everting form through large, sharp directional and/or diameter changes or contorted, dislocated or constricted zones in said pipe or conduit. The use of said guiding means makes said method particularly suited to the installation of repairs in pipes and conduits of a sinuous or tortuous nature incorporating sharp, large directional changes or changes in diameter or alignment.

In the method taught by PCT Patent Application No.

PCT/AU98/00988, the local attachment of said guiding means to said everting form and said repair material is only frictional. In consequence, during negotiation by said everting zone of said everting form of large, sharp directional changes or misalignment of joints resulting in a reduction in cross-sectional area, relative movement can occur between said guiding means and said everting form (and, as appropriate, said repair material) resulting in a retardation of the eversional progress of said everting form or said repair material. The result may be a concertina-like bunching of said everting form or said repair material within said conduit in a zone behind the everting zone if excessive tension is applied to said guiding means in an attempt to negotiate said feature causing said retardation of eversional progress. Said bunching may form, effectively, a tight-fitting plug which acts to completely arrest eversional progress. It has been found in practice that, if said guiding means are attached to the inner surface of said everting fori and said repair material throughout the length of.said everting form from its trailing or moving end to a point close to its everting zone, then their effectiveness in guiding said everting zone through large, sharp directional changes or changes in diameter in a pipe or conduit is substantially enhanced. Where said guiding means.are attached to the inner surface of said everting form and said repair material, the means of attachment must necessarily be able to be readily broken or ruptured to permit the separation of the two at the point of eversion.

The object of the present invention is to provide guiding means which may be used to effectively guide the everting zone of said everting formn and said repair material through large, sharp directional changes in said pipe or conduit, and means of attaching said guiding means to said everting fornn and said repair material in a way which will allow said guiding means to perform their intended function but which permit the ready separation of said guiding means from said everting form and said repair material at the point ofeversion.

According to the present invention, one or more pieces of suitably shaped fibrous, woven, knitted, sheet repair material in tubular form are impregnated with a settable resin and attached in appropriate positions to the inner surface of an everting form made from a suitable thin, soft, flexible, fluid-tight material or combination of materials. The means of attachment of said repair material to said everting form are such as to permit ready separation of the two following curing of said settable resin.

Guiding means in the form of a tape, cord, fabric tube or tubular web extend along and throughout the length of the un-everted part of said everting form and said repair material and are bonded or otherwise attached to its inner surface. Said everting form with said repair material is rolled onto a drum rotationally supported within a pressurisable container and its free end is led out through and sea!ingly clamped over the open end of a delivery tube formed as an extension of said pressurisable container. An extension of said guiding means is passed along and through the section of said pipe or conduit to be repaired and its distal end is led to a winch or other suitable means of applying tension to it. The end of said delivery tube is presented to the open end of said section of pipe or conduit to be repaired and fluid pressure is applied to the interior of said pressurisable container to induce progressive eversion of said everting form from said delivery tube and into said pipe or conduit, thereby carrying said repair material with it into said pipe or conduit. Tension applied to said guiding means directly or by means of their said extension acts to guide the everting zone of said everting form through large, sharp directional changes or changes in diameter in said pipe or conduit. When said everting form and said repair material are fully everted into said pipe or conduit, fluid pressure within it is maintained in order to urge said repair material into intimate contact with the inner surface of said pipe or conduit and to maintain it so until completion of curing of said settable resin with which it is impregnated. A heated fluid may be passed through the interior of said everting form in order to accelerate curing of said resin. When said resin is properly cured, tension is applied to a retrieval tape passing along and through the everted length of said everting form and connected to its distal end. Said tension acts to cause said evenrting fori to de-evert, reversing its process of eversion until it is fully withdrawn from said pipe or conduit, said everting form peeling away from said cured repair material as the zone of deeversion passes it, leaving said repair material in place securely bonded to the inner surface of said pipe or conduit.

The various aspects of the present invention will be more readily understood by reference to the following description of preferred embodiments given in relation to the accompanying drawings in which: Figure 1 is a longitudinal cross-sectional view of a bend of a pipe or conduit through which said everting formnn and said repair material are being deployed using a first form of guiding means; Figure 2 is a longitudinal cross-sectional view of a bend of a pipe or conduit through which said everting form and said repair material are being deployed using a second form of guiding means; Figure 3 is a is a longitudinal cross-sectional view of a straight part of a pipe or conduit through which said everting form and said repair material are being deployed using the first form of guiding means; Figure 4 is a transverse cross-sectional view of a straight part of a pipe or conduit through which said everting form and said repair material are being deployed using the second form of guiding means; Figure 5 is a transverse cross-sectional view of a bend of a pipe or conduit through which said everting form and said repair material are being deployed without use of guiding means; Figure 6 is a face view of a third form of guiding means; Figure 7 is a transverse cross-sectional view of a straight part of a pipe or conduit through which said everting form and said repair material are being deployed using the guiding means depicted in Figure 6.

With reference to Figure 3, everting form 1 is depicted in the process of eversion into straight section 2 of a pipe or conduit. In all embodiments, said everting form is made from a suitable soft, flexible, pressure-tight, film material in continuous form and is fed out from and pressurised with a suitable fluid from a pressurisable container or launcher vessel as taught by PCT Patent Application No. PCT/AU98/00988. At its everting zone 29 immediately beyond eversion point 5, said everting form acts as a diaphragm and, with an effect analogous to a piston, exerts a force under the influence of said pressurising fluid to drive said everting zone of said everting form and said repair material along said pipe or conduit. At said everting zone, said repair material is carried or displaced from the interior of said everting form to its exterior, thereby bringing said repair material into position against the inner surface of said pipe of conduit. Said everted part of said everting form is maintained fully inflated to retain said resin-impregnated repair material against the inner surface of said pipe or conduit until said settable resin is properly cured.

Guiding means in the form of tape, wire or cord 3 are attached as appropriate to the inner surfaces of un-everted part 4 of said everting form and repair material 28 and tension applied to said guiding means directly or through their extension (not shown) assists in guiding the zone of eversion of said everting form and said repair material through large, sharp directional changes in said pipe or conduit. At eversion point 5, said guiding means attached to the inner surfaces of the un-everted part 4 of said everting form and said repair material peel or tear away from said everting form and said repair material and become detached. In the preferred embodiment, said guiding means are bonded to the inner surfaces of the uneverted part 4 of said everting form and said repair material by means of a suitable adhesive. In its cured state, said adhesive provides high longitudinal shear attachment to said everting form and said repair material, but low tear strength or resistance to peeling at the point of eversion. In the preferred embodiment, said adhesive is a room temperature-vulcanising silicone rubber sealing compound or a weak, latex or rubber-based contact adhesive in single application, both of which tear or peel easily away from the smooth surface of said everting form and said repair material. Said adhesives are applied to said guiding means in a narrow, more or less continuous application or in discrete applications, closely-spaced in an axial sense. -Care is taken to ensure that said guiding means and said adhesives do not mask or otherwise impede the subsequent process of impregnating said repair material with said settable resin. In an alternative embodiment used where said guiding means take the fornn of a flat tape, a double-sided adhesive tape is employed to attach said guiding means to the inner surfaces of said everting form and said repair material. In further alternative embodiments, suitable mechanical means are employed to attach said guiding means to the inner surfaces of said everting form and said repair material, said attachment means comprising stitching, tacking, stapling or frictional attachment elements providing high longitudinal shear, but rupturing or breaking readily at the point of eversion.

With reference to Figure 4, guiding means in the form of a fabric tube or tubular web 6, 8 extend along and through the length of un-everted part 4 of everting form I and repair material 28 and are bonded or attached to the inner surfaces of said everting form and said repair material in the same way as described in relation to Figure 3. The diameter of said fabric tube or tubular web is preferably the same as the internal diameter of said inverting form and said repair material and preferably takes the form of a light, open-weave fabric of suitable tensile strength or what is commonly known as 'onion bag' material, a strong net material in which intersecting threads or filaments are fused or adhered to each other.

During eversion of said everting form and said repair material, tension applied to extended part 7 of said guiding means acts to assist in drawing un-everted part 4 of said everting form and said repair material through the everted part 1 of said everting form. Said guiding means detach from and peel away from said everting form and said repair material at point 9. Said arrangement better distributes the drawing force applied to said everting form through said guiding means and, as described in relation to Figure. 2, provides better guidance of said everting zone through large, sharp directional changes in pipe or conduit 2 to.be repaired.

With reference to Figure 5, depicted are stages of the progressive eversion of everting form 1 with said repair material into bend 10 of pipe or conduit 2 without the use of guiding means. It can be seen that, at the stage of eversion depicted by the feature numbered 11, all parts of said everting form and said repair material have progressed equally. However, at the stage of eversion depicted by the feature numbered 12, it can be seen that contact with the inner wall of bend 10, and thereby the development of frictional forces, has inhibited eversionary progress of the part of said everting form and said repair material abutting said bend. At the stage of eversion depicted by the feature numbered 13, the effect of wall contact has been accentuated, with a substantial collapsing of eversionary progress on the side of said everting form abutting said bend. Simultaneously, the most forward part of the eversion zone of said everting form and said repair material may, in fact be deflected towards the collapsing side, the effect being one of a capturing of said everting zone by said bend with a complete interruption of eversionary progress. Such effect renders necessary the use of said guiding means. It can be demonstrated that, in an everting form carrying with it repair material and without the provision of said guiding means, its zone of eversion is unlikely to negotiate a smooth bend with a large, sharp directional change exceeding approximately 45' In contrast, the zone of eversion of the same said everting form and repair material, when said guiding means are employed, can be made to readily negotiate a smooth bend with a large, sharp directional change exceeding 180'.

With reference to Figure 1, everting form 1 is depicted in the process of eversion through bend 10, guided by guiding means in the form of flat tape 3. Said guiding means are bonded or attached to the inner surface of said everting form and said repair material in the same way as described in relation to Figure 3. Tension applied to said guiding means substantially compresses the part 18 of the everting zone of said everting form and said repair material adjacent zone 17 at the inside of bend allowing expansion of the part 16 of said everting zone adjacent the outside of said bend such that it substantially fills the lumen of said pipe or conduit, thereby facilitating its eversionary progress. At the stage of eversionary progress depicted, said everting zone has been stretched into a generally eliptical shape and the resultant tension generated across the major axis 21 of said everting zone acts to draw or urge part 16 around bend Adhesion or attachment of said guiding means to said everting form and said repair material peels or tears away from the surface adjacent part 16 at point 14 and from the surface adjacent part 18 at point 15. The combined effect is such that eversionary negotiation of bend 10 by everting form 1 and said repair material is facilitated.

With reference to Figure 2, everting form 1 together with said repair material are depicted in the process of eversion through bend 10, guided by guiding means in the form of a fabric tube or tubular web 6, 8. Said guiding means are bonded or attached to the inner surface of said everting form in the same way as described in relation to Figure 3. Tension applied to said guiding means through their extension 7 substantially compresses the part 18 of the everting zone of said everting form and said repair material adjacent zone 17 at the inside of bend 10, allowing expansion of the part 16 of said everting zone adjacent the outside of said bend such that it substantially fills the lumen of said pipe or conduit, thereby facilitating its eversionary progress. At the stage of eversionary progress depicted, said everting zone has been stretched into a generally eliptical shape and the resultant tension generated across the major axis 21 of said everting zone acts to draw or urge part 16 around bend 10. At the same time, it is apparent that tension applied directly to part 16 of said everting zone by fabric tube or tubular web 6 acts to draw part 16 around bend 10. Adhesion or attachment of said guiding means to said everting form and said repair material peels or tears from the surface adjacent part 16 at point 20 and from the surface adjacent part 18 at point 19 and along the intermediate surfaces between points 19 and 20. The combined effect is such that eversionary negotiation of bend 10 by everting form 1 is more effectively facilitated.

With reference to Figures 6 and 7, one or more tape-type guiding means 26 are sewn or otherwise fastened into said everting form and said repair material prior to their closure into tubular form in preparation for their eversion into a pipe or conduit 2 being repaired. In the preferred embodiment, said guiding means are made from a .suitable material combining high longitudinal shear strength with tearability. In the preferred embodiment, said material is a fibre-reinforced paper material 13 which has been treated to prevent its being softened by contact with water or said settable resin. Said guiding means pass along and through the full length of the interior of said everting form said repair material and are sewn or bonded to it along typical lines 23. Said repair material (not shown) is fixed and contained within said everting form and zones 22 of said guiding means are optionally sewn to it to secure it in place. An extension (not shown) is securely attached to the free end of said guiding means to allow tension to be applied to said guiding means for the purpose of guiding the everting zone of said everting form and said repair material. A more or less centrally-located longitudinal zone 25 of said guiding means is reinforced to substantially increase its tensile strength. In the preferred embodiment, said reinforcement takes the form of a lamination of a suitable scrim material. Narrow longitudinal zones 24 immediately adjacent said reinforced zone are weakened such that the two un-reinforced zones 22 of said' guiding means readily tear away from said reinforced zone at the point of eversion of said everting form and said repair material. At said point of eversion, said un-reinforced zones tear away from said reinforced zone and, being attached to said everting form and, as appropriate, said repair material, are everted with them and carried into position against the inner surface of said pipe or conduit being repaired. Said separated reinforced zone continues to extend beyond said point of eversion, carrying tension applied for the purpose of guiding said everting zone.

Where said guiding means take the form of said fabric tube or tubular web, said adhesives are preferably used in applications closelyspaced in an axial sense throughout the length of said everting form. The term closely spaced can be taken to mean applications spaced no further apart in an axial sense than 50 millimetres. In alternative embodiments, said applications of adhesive are separated in an axial sense by distances of up to 500 millimetres. Application of adhesive is readily achieved with said guiding means laid flat on a suitable surface and a suitable dispenser used to apply strip applications across the width of said guiding means and orientated more or less normal to their longitudinal axis.

Where all said forms of said guiding means pass over or across said repair material attached within said everting form, said guiding means are bonded to said repair material in the same way as to said everting form.

During subsequent impregnation of said repair material with said settable resin, said guiding means do not inhibit access of said resin to said repair material. Where said guiding means take the form of a tape or cord or strip material as described in relation to Figures 6 and 7, said resin material is able to satisfactorily pass around or through said guiding means and effect proper impregnation of said repair material. Where said guiding means take the form of said fabric tube or tubular web, as described in relation to Figures 2 and 4, said resin material is able to satisfactorily pass between the warp and weft. of the fabric or the threads or filaments of the 'onion bag' material of said guiding means and effect proper impregnation of said repair material.

Obviously, said guiding means may be attached to said everting form and to said repair material by any suitable adhesive or mechanical attachment means. Said attachment means must accommodate forces applied in the axial direction of said everting form and said repair material, but permit ready separation or detachment of said guiding means from said evenrting form and said repair material by breaking, rupturing or a peeling action generated at said zone of eversion by tension applied to said guiding means as said zone of eversion is impelled forwardly by said fluid pressure applied to the interior of said evenrting form. Tension applied to said guiding means does not act to impel forwardly said zone of eversion, but serves to guide said zone of eversion through directional changes and discontinuities in said pipe or conduit and prevents localised axial differential movement between said evenrting form and said repair material immediately upstream of said zone of eversion while permitting the required freedom of differential movement between said evenrting form and said repair material in the immediate said eversion zone.

If said guiding means are not attached to the inner surface of said evenrting form and said repair material more or less continuously throughout its length from its trailing or moving end to a point close to its evenrting zone, then tension applied to said guiding means may cause the trailing or moving end of said everting form and said repair material, to which said guiding means are attached, to travel along said pipe or conduit at a higher speed than said zone of eversion, thereby creating a localised bunching up of said everting form and said repair material. This effect is particularly evident where said everting form is passing around a bend or deviation and, in smaller diameter pipes or conduits, may be sufficiently obstructive as to cause fluid pressure to be cut off from said zone of eversion. Where this occurs, further tension applied to said guiding means merely acts to exacerbate the bunching effect and obstruction.

In all cases herein, the term 'everting form' should be taken to mean, as appropriate, the combination of said everting form together with said resin-impregnated repair material carried with it. In the case where a long repair is to be installed in a pipe or conduit, it may, in fact, occupy almost the whole length of said everting form and said guiding means are attached to said repair material throughout its length in the manner described and to said everting form only at its closed end. In the case where a short repair is to be carried deep within a pipe or conduit from the point of entry on a proportionately much longer everting form, said guiding means are also attached as required to said everting form throughout its length and at its closed end. Where said everting form is made from very thin, soft, flexible film material and particularly where repairs are installed in pipes and conduits of larger diameter, said guiding means may be attached to said everting form at points substantially more widely separated than normal. Said points of attachment of said guiding means to said everting form may be separated in an axial sense by as much as one to two metres or greater distances and, in some cases, it may only be necessary for said guiding means to be attached to said repair material in the way described and to said everting form only at its closed end. Where said everting form is made from thicker, less compliant film material and particularly where repairs are installed in pipes and conduits of smaller diameter, said guiding means must be attached to said repair material in the way described and to said everting form throughout its length at appropriately spaced points and at its closed end.

Where said repair material comprises several discrete layers of material and said guiding means are bonded to what may be termed the inner layer of said repair material prior to its eversion, tension applied to said guiding means may result in differential movement between said layers of said repair material. Where this may occur, said layers of said repair material are loosely connected by suitable mechanical means which permit a degree of localised differential movement between said layers, but prevent gross differential movement. In the preferred embodiment, said mechanical connection means take the form of loose stitching, sewing, tacking or stapling.

Claims (34)

1. A method of guiding an everting form employed to carry formed-in-situ repair material into a pipe or conduit, said method comprising passing guiding means through the interior and along the full length of said everting form in its un-everted state; fixing a first end of said guiding means to a substantially closed end of said everting form; attaching said guiding means in a readily detachable way to the interior surfaces of said everting form and said repair material substantially throughout the length of said everting form; and, during eversion of said everting form, applying tension to a second end of said guiding means through an extension of suitable length such that force applied to said guiding means is transmitted generally to said everting form and said repair material throughout their un-everted lengths and in particular to both said parts at the zone of eversion, thereby assisting in guiding the transition of said zone of eversion through directional changes and discontinuities in said pipe or conduit and preventing localised axial differential movement between said everting form and said repair material immediately upstream of said zone of eversion whilst permitting the required freedom of differential movement between said everting form and said repair material in the immediate said eversion zone.

2. A method according to Claim 1 in which said guiding means take the form of one or more flat tapes.

3. A method according to Claim 1 in which said guiding means 19 take the form of one or more cords, wires or the like.

4. A method according to Claim I in which said guiding means take the form of a tube of knitted or woven fabric.

5. A method according to Claim 1 in which said guiding means take the form of a tubular web of strong, interconnected, filamentary material such as that known as 'onion bag'.

6. A method according to Claim 1 in which said guiding means are attached to the inner surfaces of said everting form and said repair material by means of an adhesive providing high longitudinal shear attachment but low tear strength or resistance to peeling.

7. A method according to Claim 6 in which said adhesive is a silicone rubber sealing compound.

8. A method according to Claim 6 in which said adhesive is a weak latex or rubber-based contact adhesive in single application.

9. A method according to Claim 1 in which said guiding means are attached to the inner surfaces of said everting form and said repair material by means of double-sided adhesive tape.

A method according to Claim I in which said guiding means are attached to the inner surfaces of said everting form and said repair material by means of self-adhesive forms of the complementary parts of a hook and loop attachment system such as that known by the trade name, Velcro.

11. A method according to Claim 1 in which said guiding means are attached to the inner surfaces of said repair material by means of a self- adhesive form of the hook part of a hook and loop attachment system such as that known by the trade name, Velcro, said hook part being self- adhesively attached to said guiding means with its hooks engaging the soft surface of said repair material.

12. A method according to Claims 10 and 11 in which one or both parts of said hook and loop attachment system are attached to said guiding means and to the inner surfaces of said everting form and said repair material by stitching, sewing, tacking or stapling.

13. A method according to Claim 1 in which said guiding means are attached directly to the inner surfaces of said everting form and said repair material by means of weak stitching, sewing, tacking or stapling.

14. A method according to Claim 1 in which said means of attaching said guiding means to the inner surfaces of said everting form and said repair material take the form of one or more axially-arranged applications extending more or less continuously throughout the attached length of said guiding means and, in the case of said adhesive means, each having a width less than one tenth of the circumference of said everting form.

A method according to Claim 1 in which said means of attaching said guiding means to the inner surfaces of said everting form and said repair material take the form of one or more axially arranged applications, each comprising a plurality of discrete applications 21 throughout the attached length of said guiding means and, in the case of said adhesive means, each having a width less than one tenth of the circumference of said everting form.

16. A method according to Claim 15 in which said discrete applications of said means of attachment are separated axially by distances in the range 25 to 200 millimetres.

17. A method according to Claim 15 in which said discrete applications of said means of attachment are separated axially by distances in the range 200 to 400 millimetres.

18. Apparatus for guiding an everting form employed to carry formed-in-situ repair material into a pipe or conduit, said apparatus comprising one or more soft, flexible guiding means of high tensile strength which pass through the interior and along the full length of said everting form in its un-everted state, a first end of said guiding means being fixed to a substantially closed end of said everting form, said guiding means being attached in a readily detachable way to the interior surfaces of said everting form and to said repair material substantially throughout the length of said everting form such that, during eversion of said everting form, tension may be applied to a second end of said guiding means through an extension of suitable length such that force applied to said guiding means is transmitted generally to said everting form and said repair material throughout their un- everted lengths and in particular to both said parts at the zone of eversion, thereby assisting in guiding the transition of said zone of eversion through 22 directional changes and discontinuities in said pipe or conduit and preventing localised axial differential movement between said everting form and said repair material immediately upstream of said zone of eversion whilst permitting the required freedom of differential movement between said everting form and said repair material in the immediate said eversion zone. material immediately upstream of said zone of eversion whilst permitting the required freedom of differential movement between said everting form and said repair material in the immediate said eversion zone.

19. Apparatus according to Claim 18 in which said guiding means take the form of one or more flat tapes.

Apparatus according to Claim 18 in which said guiding means take the form of one or more cords, wires or the like..

21. Apparatus according to Claim 18 in which said guiding means take the form of a tube of knitted or woven fabric.

22. Apparatus according to Claim 18 in which said guiding means take the form of a tubular web of strong, interconnected, filamentary material such as that known as 'onion bag'.

23. Apparatus according to Claim 18 in which said guiding means are attached to the inner surfaces of said everting form and said repair material by means of an adhesive providing high longitudinal shear attachment but low tear strength or resistance to peeling.

24. Apparatus according to Claim 23 in which said adhesive is a silicone rubber sealing compound.

Apparatus according to Claim 23 in which said adhesive is a weak latex or rubber-based contact adhesive in single application.

26. Apparatus according to Claim 18 in which said guiding means are attached to the inner surfaces of said everting form and said repair material by means of double-sided adhesive tape.

27. Apparatus according to Claim 18 in which said guiding means are attached to the inner surfaces of said everting form and said repair material by means of self-adhesive forms of the complementary parts of a hook and loop attachment system such as that known by the trade name, Velcro.

28. Apparatus according to Claim 18 in which said guiding means are attached to the inner surfaces of said repair material by means of a self- adhesive form of the hook part of a hook and loop attachment system such as that known by the trade name, Velcro, said hook part being self- adhesively attached to said guiding means with its hooks engaging the soft surface of said repair material.

29. Apparatus according to Claims 27 and 28 in which one or both parts of said hook and loop attachment system are attached to said guiding means and to the inner surfaces of said everting form and said repair material by stitching, sewing, tacking or stapling.

Apparatus according to Claim 18 in which said guiding means are attached directly to the inner surfaces of said everting form and said repair material by means of weak stitching, sewing, tacking or stapling.

31. Apparatus according to Claim 18 in which said means of attaching said guiding means to the inner surfaces of said everting form and said repair material take the form of one or more axially-arranged applications extending more or less continuously throughout the attached length of said guiding means and, in the case of adhesive means, each having a width less than one tenth of the circumference of said everting form.

32. Apparatus according to Claim 18 in which said means of attaching said guiding means to the inner surfaces of said everting form and said repair material take the form of one or more axially arranged applications, each said application comprising a plurality of discrete applications throughout the attached length of said guiding means and, in the case of adhesive means, each having a width less than one tenth of the circumference of said everting form.

33. Apparatus according to Claim 32 in which said discrete applications of said means of attachment are separated axially by distances in the range 25 to 200 millimetres.

34. Apparatus according to Claim 32 in which said discrete applications of said means of attachment are separated axially by distances in the range 200 to 400 millimetres.