IMPROVEMENTS RELATING TO THE LINING OF PIPELINES OR PASSAGEWAYS

Abstract: The method provides that a pipeline (10) or passageway (10) wall is coated using a backstop means, a body of resinous material (6) and an everting tube (5). These items are located inside the passageway to be lined and moved there along with the backstop (1) providing support for the bulk of resin material and also applying pressure via the resin material onto the everting face (16). When the everting tube is a resin absorbent material, the presence of the bulk of the fluent material prevents air from becoming entrained in the everting face and prevents voids in final lining. The resin may be introduced via a tee piece (12) through the lag thereof whilst the everting tube is introduced along the arms of the tee.

Description: IMPROVEMENTS RELATING TO THE LINING OF PIPELINES OR PASSAGEWAYS This invention relates to the lining of pipelines or passageways in which a synthetic composition is utilised either as an adhesive or to form in itself a layer which forms a coating on the pipeline or passageway surface. In specific examples, the coating material is a curable synthetic resin, which may be of the ambient cured type or maybe of a type which requires initiation for example by heat or light or other means to commence the cure. Lining processes in which curable synthetic resin is used are known, and typical of such a process is described in British patent specification no. 1449455. As described in that patent specification, a lining process for an underground passageway such as a sewer involves the use of a flexible lining tube which comprises a resin absorbent inner layer such as a fibrous felt, and an impermeable outer layer. To insert the flexible tube into the pipeline or passageway to which the tube is sized, the tube is everted using fluid pressure, typically a head of water. The resin impregnated fibrous inner layer is therefore turned inside out and is presented to the surface to be lined. When the lining tube has been applied fully, the resin soaking the ' absorbent layer is cured so that in fact the resin absorbent layer and the cured resin form a rigid lining shell or skin on the passageway surface. The impermeable membrane may serve as a surface to the finished tube, or it may alternatively be removed. This lining process is extremely successful and is used throughout the world and is in fact known as the Tnsitufor (Registered trademark) process. The flexible lining tube TITUTESHEET comprising the inner fibrous, layer and the outer impermeable layer is trademarked by the name Insitutube. The present invention has specific application to processes involving the applying of Insitutubes to underground passageway surfaces, but varies in concept from the Insituform method described above. l n In its widest aspect, the present invention comprises the application of a fluent coating or lining material to a pipeline or passageway surface wherein a bulk of the fluent coating material is housed in the pipeline or 15 passageway between an everting face of an inwardly travelling lining tube and a backstop means ensuring the creation of a pressure from the body of fluent material against the everting face, so that the everting face the body of fluent material and the backstop move along the 20 surface to be lined whereby the coating material is progressively applied to the surface by being carried by the everting face. It is preferred that the backstop be a "rolling pig" 25 which comprises a tubular member of a flexible material with the ends turned back on themselves and connected together. The pig is inflated and will roll upon itself as the coating proceeds along the passageway. 30 The everting tube preferably is an Insitutube comprising an inner fibrous absorbent layer and an outer impermeably membrane, in which case the invention has the significant advantage that a void free Insitupipe bonded or bendable to the original surface results. The method may comprise 35 the provision of a launching tee piece located at the end of the pipeline or passageway and into which the body of the fluent composition can be loaded. The everting tube enters the tee from one arm and exits via the other arm directly into the pipeline or passageway moving the body 40 of fluent material into the passageway as it progresses. This method is particularly suitable for applying thick coatings to, for example, steel pipelines for the purposes of corrosion protection. It is particularly useful for drinking water pipes and will suitably replace the conventional lining method for such pipes which comprises the application of cement mortar. More recently such pipes have been lined by a spray on technique using epoxy resin, a process which has met with some success. An embodiment of the present invention is illustrated by way of example only with reference to the accompanying drawings wherein;- Fig 1. is a sectional side elevation showing the leading end of the pipeline or passageway to be lined; and Fig 2. is a view showing the process after the rolling pig and everting face have moved somewhat along the passageway. Referring to the drawings, a flexible lining tube (5) which typically will have an inner felt layer of no more than 3 mm in thickness, and an outer impermeable coating which may be removable at the end of the process. The felt is impregnated with resin prior to use and the ends are sealed. The pipeline (10) to be lined using the Insitutube is initially cleaned, and where the pipe is of metal, it is preferably cleaned back to the bare metal surface by any suitable cleaner device. A launching tee piece (12) is fixed so that one arm (12a) is connected to the end of the pipe (10) whilst the other arm (12b) has a feed elbow (14) aligned therewith. The leg (12c) of the launching tee piece provides a means SUBSTITUTESHEET for charging curable synthetic resin into the tee piece and into the leading end of the passageway (10). The leg (12a) is sealed to the leading end of the pipe (10) by means of a temporary seal (4). Into the passageway (10) at the appropriate end is introduced a rolling pig (1). A rolling pig as described herein comprises a length of flexible tubing of which the ends are turned backwards upon the tube and are connected together so that the tube becomes endless and can roll upon itself as will be understood. The pig is in fact inflated by suitable inflation means through a one-way valve, and when it is inflated to the required pressure it will form a seal on the inner surface of the passageway (10). A tape or rope (2) passes through the centre of the pig, and out through the leg (12c) as shown and forms a means for holding the pig back from travelling freely along the passageway (10). The tape or rope (2) passes to the outside of the pig, and is returned as shown to the outlet of arm (12b) of the launching tee piece as indicated by reference (3). The Insitutube (5) is inverted through the connecting elbow (14) using water as shown or alternatively air under pressure after the leading end of the tube (5) is turned back upon itself so that the water pressure will cause the tube to evert along the arms of the tee and into the passageway (10). An appropriate quantity of the resin (6) is introduced into the space between the pig and the everting face (16) of the tube (5) to completely fill such space and to displace any air therefrom. As the resin is poured in, the tape (2) is released by being fed out to allow the rolling pig to move down the pipeline to the appropriate position. The tube (5) is now everted, and before it closes the open end of the arm (12b) of the tee, any excess amount of the tape (2) is cut off so that it does not impede the progress of the pig along the passageway as will be explained. TESHEET As eversion continues the rolling pig (1) will move ahead of the body of resin (6) holding said reservoir against the everting face and by this means the everting face constantly is in contact with the resin reservoir thereby providing the significant advantage of excluding the entry of air into such face and in particular into the fabric layer whereby voids in the resulting lining are avoided. If the passageway (10) has any side connections then of course it is necessary to ensure that such side connections are blocked off before the process commences as otherwise such side connections would fill with resin as the body or reservoir of resin (6) passes. A simple method of achieving this block-off is to pre-line the passayiway (10) with for example a flexible tube of synthetic plastics material, a procedural step which is quite simple. When the pig reaches the downstream end of the pipeline, suitable arrangements can be made to catch the pig and any excess resin. In an alternative arrangement, an ordinary pipe pig of any of the commercial forms e.g. a piston, plug or the like may be used although the use of such pigs gives a greater risk of the process being impeded due to the pigs sticking in the passageway. The rolling pig may be of a fabric reinforced rubber or plastics material. It will be appreciated that the Insitutube may be replaced by an alternative form of tube such as a standard, multi-layered structure, but in any case the method does achieve the prevention of air and water entrainment during eversion. In another modified method, the Insitutube is used but is SUBSTITUTESHEET not initially impregnated internally with resin, in which case sufficient resin must be provided in the reservoir (6) to effect complete impregnation of the absorbent layer of the tube when it is introduced through the down- tube (14) and the tee (12). In this case a vacuum is applied to the inside of the lining tube to remove air to ensure that the everting face will fully impregnate with resin. In the methods described, the resin may be of a type which is cured by curing means such as heat and/or light, but the invention can also be applied where the resin is of the ambient cured type. Another variation in the method can be provided when the Insitutube is a coated fabric or thin felt impregnated with one part of a two part resin system (the one part may be toughened acrylic) and the second part such as an initiator is introduced between the rolling pig and the Insitutube by means of a reservoir (6). When the two parts come together in the passageway they will react to a depth of a millimetre or more without intimate mixing and the toughened acrylic will harden in a few seconds. In this instance the resin and felt or fabric may act as a means to secure the coating to the passageway wall. The advantages of these methods of corrosion protection over the spray-on epoxy method are that the resin will always be properly mixed and a sample taken from the lining inside the launching tee will be representative of the quality of the lining inside the passageway. Spray- on systems have short comings of possible mis-metering mis-mixing and mis-spraying. SUBSTITUTESHEET

Claims: AMENDED CLAIMS [received by the International Bureau on 8 July 1991 (08.07.91); original claims 1-13 replaced by amended claims 1-10 (2 pages)] 1. A method of lining a pipeline or passageway surface wherein a Dulk synthetic resin is housed in the pipeline or passageway between an everting face of an inwardly travelling lining tube of resin absorbent material which is pre impregnated with synthetic resin and a backstop means ensuring the creation of a pressure from the body of fluent material against the everting face, so that the everting face the body of fluent material and the backstop move along tne surface to De lined. . A method according to Claim 1 , wherein the backstop is a "rolling pig" which comprises a tubular member of flexible material with the ends turned back on themselves and connected together. 3. A method according to Claim 2 wherein the pig is inflated so as to roll upon itself as the coating proceeds along the passageway. 4. A method according to Claim 1, 2 or 3 , wherein the everting tube is a tube comprising an inner fibrous absorbent layer impregnated with synthetic resin and an outer impermeable membrane. 5. A method according to any of Claims 1 to 4 including tne provision of a launching tee piece located at tne end of the pipeline or passageway and into which th bulk of synthetic resin can be loaded, the everting tube being caused to enter the tee from one arm and exit via the other arm directly into the pipeline or passageway moving the body of fluent material into the passageway as it progresses. The method according to any of Claims 1 to 5, wherein the method is used on a steel pipeline for the purposes of corrosion protection. A method according to Claim 2 or any Claim dependent thereon wherein a tape or rope passes through the inside of the pig to assist the movement of same along the pipeline or passageway. 8. A method according to any preceding Claim wherein a pre lining tube is applied to the pipeline or passageway before the insertion therein of the backstop means body of synthetic resin and everting tube. 9. A method according to any preceding Claim wherein the everting tube is a coated fabric or felt impregnated with one part a two part resin system and the second part is the body of resin between the backstop and everting tube. 10. A method according to Claim 9 wherein the said one part of the resin system may be toughened acrylic which provides a means of securing the everting tube to the passageway wall.

Inventors: SMITH EDWARD PETER, SMITH, EDWARD, PETER
Applicants: INSITUFORM GROUP LTD, INSITUFORM GROUP LIMITED
Application year: 1991
Main classification: F16L55
IPC codes: B29C63, F16L55