IMPROVEMENTS RELATING TO THE LINING OF PIPELINES OR PASSAGEWAYS

Abstract: The invention provides that an underground pipeline or passageway (10) is lined using a thermoplastic pipe. The pipe is extruded vertically downwards into a manhole (14) and then is fed into the pipeline or passageway (10) to be lined. The extrudate (34) is provided with longitudinal folds (38) so it will temporarily take up a reduced cross section. When in the pipeline or passageway (10) it is expanded up to size to line the pipeline or passageway (10) surface. It is kept hot and soft until it is expanded, when it is cooled so that it will retain its full size shape.

Description: IMPROVEMENTS RELATING TO THE LIN ING OF P IP ELINES OR PASSAGEWAYS This invention relates to the lining of pipelines and passageways, and in particular concerns the lining of such pipelines or passageways, with a tube or lining of thermo¬ plastic material which is of a nature such that it is folded longitudinally . in order to reduce its overall dimensions, to enable the lining tube to be inserted into the pipeline or passageway, and subsequently can be re- expanded up to the pipeline or passageway size so as to line the surface thereof, which constitutes its final form. In order to enable the plastics material to go through these stages, it needs to be heated so that it will be soft when it is in position in the pipeline or passageway, but before being expanded up to the pipeline or passageway size. There are already a number of methods for lining pipelines or passageways using thermo-plastic lining pipes, and one such method comprises extruding the plastic lining pipe followed by the immediate folding of same, followed by cooling and coiling onto a storage drum. The storage drum is taken to the site where the pipeline or passageway, which usually will be underground, has to be lined, where at the folded and coiled lining pipe is unwound, and is heated to soften same, and it is fed into the pipeline or passageway down a man-hole and then along the pipeline or passageway to be lined. When the hot folded lining tube is in position, its interior is pressurised to expand same onto the pipeline or passageway surface, followed by cooling of the lining pipe so that it will solidify in place and remain in place when the inflating pressure is removed. Other systems are known but generally speaking they follow the lines of the method described above. The present invention is also concerned with the insertion of a thermo-plastic pipe into a pipeline or passageway and, with the expansion of the thermo-plastic pipe, when hot, onto the pipeline or passageway surface but the present invention provides that the method can be used for the lining of extremely long lengths of pipeline or passageway, the known methods being limited to the length of coiled p pe which can be taken to site. In accordance with the general method of the invention, the thermo-plastic lining pipe is extruded on site in a substantially vertical downwards direction into a man-hole and the extruded pipe is guided down the man-hole and into the pipeline or passageway to be lined, whilst the exterior of the extruded lining pipe is kept warm and the pipe therefore soft by virtue of heating fluid surrounding the extruded lining pipe, and the lining pipe either being extruded in a folded form so that it is of reduced overall dimension enabling it to be passed into the pipeline or passageway, or being folded or formed after extrusion into such reduced size, and the soft, hot and folded extruded lining pipe being expanded when in the pipeline or passageway onto the pipeline or passageway surface and 'eventually being cooled so as to remain in position on such surface. The extruded lining pipe may be applied to the pipeline or passageway surface by being everted onto such surface, the pipe expanding as it everts, or alternatively it may be pulled into position, until it extends for the full length of the * pipeline or passageway to be lined. When it reaches such position it may be expanded by introducing fluid under pressure into the interior of the lining pipe either directly or by everting an expansion tube into the lining pipe. It is preferred that the exterior of . the extruded lining pipe in addition to being kept warm by means of heated fluid, will also be kept under pressure by said fluid in order for example to keep the lining pipe in the said folded condition. To assist in the pulling of the lining pipe into the pipeline or passageway, a pull-rope may be fed through the extruder so as to emerge in the centre of the extrudate which, after folding, engages the central rope, and is held suitably thereto by virtue of the friction which arises as a result of pressuring the exterior of the lining pipe by the said heated fluid. By virtue of the said invention, theoretically infinitely long pipelines or passageways can be lined, and the lining pipe thickness can be accurately controlled. Additionaly, the . manner in which the pipe is folded can be controlled and varied with ease. It is particularly suitable for example to fold the pipe so that in its reduced outer size, it will define a star configuration. Such folding enables the lining pipe to travel readily around bends and curves in the pipeline to be lined. Any suitable thermo-plastic may be used for the lining pipe, such material to include p.v.c. or any of the polyolefins. Because an extruder which extrudes vertically downwards is utilised, it is also possible to feed into the centre of the extruder a fabric tube which forms reinforcement for the interior of the extrudate, and if the extruded tube is eventually everted inside the pipeline or passageway, the reinforcement tube will be presented to the pipeline or passageway surface. This fabric layer may form a useful anchoring means if the extruded pipe is to be anchored to the pipeline or passageway suface, for example using a curable synthetic resin as adhesive or bonding medium. An embodiment of the present invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing, wherein the single figure shows one method of realisation of the present invention. Referring to the drawing, an underground passage (10) to be lined in accordance with this embodiment of the invention extends between a pair of man-holes (12) and (14) extending from the passage (10) to ground level (16). At ground level adjacent the man-hole is a winch (18), the purpose of which is to winch a pull-rope cable or the like (20) to assist the lining operation as will be described. At the other man-hole (14) at ground level there is a generator and boiler unit (22) for electricity supply and supply of hot water which is in fact ejected through an outlet water pipe (24) to a head (26) whose function will be described hereinafter. Also at the man-hole (14) is an operational vehicle (28) housing an extruder (30) which supplies plastic material to a cross-head extruder (32) as shown to exude an extrudate (34) in a vertically downwards manner. The extrudate is in the form of a circular pipe which is formed into folded configuration by folding rollers (36), so that the extrudate is for example formed into the star configuration shown at (38). The thus formed extrudate is folded around a central rope (20) which extends entirely through the man- hole and the passageway (10) to be lined and onto the winch (18). The rope (20) is fed from a .supply (40) carried by the vehicle and passes through the centre of the extruder cross-head (32). An orifice valve arrangement (42) enables the downstream chamber (44) which is defined by a pipe (46), and the end of the extradate (48) which has been inverted and attached to the pipe (46) by a clamp (50), to be pressurised with water supplied from the head (26). It will be appreciated that when the extrudate is initially extruded, the leading end is turned upon itself and connected to the end of the pipe (46) at location (50), and hot water is supplied through the head (26). Head (26) is of a type which will be self propelled in that the hot water issues from the rear of the head, and therefore the head is forced forwards as far as possible so that as shown on the drawing as the extrudate everts in the region of the everting face (52), so the head (26) remains close to such face and supplies hot water to assist in the eversion, and also to keep the inwardly travelling portion (54) of the extrudate in a soft condition so that it will expand freely at the everting face (52) as that face travels along the passageway (10) . The valve (42 ) serves to maintain the pressure in the chaamber (44), but if there is any excess pressure water is in fact bled upwardly through the valve (42), and will return to the boiler via the return line (56). The extruding operation will be discontinued when the everting face (52) is approximately halfway along the passageway (10), so that the trailing end of the extrudate will arrive in the region of the man-hole (12). Some means may have to be provided in order to seal the trailing end of the extrudate so that the pressure can be maintained inside the extrudate and the hot water can be replaced with cold water in order to cure the extrudate material which is thermo-plastic in nature. By virtue of keeping the inwardly travelling portion (54) under heat and pressure, so there will be no tendency for the folds of the extrudate to unfold prematurely, and furthermore the extrudate will be pressed firmly into frictional contact with the rope (20) so that any pull in the rope will clearly assist the eversion process. The extrudate may be of any suitable material such as p.v.c. or a polyolefin. The use of the rope (20) can be employed to assist in the control of the speed of extrusion. Additionally, it is possible to feed other members into the cross-head (32), such other members comprising for example fabric tubes which will eventually be everted with the extruded lining tube so as to lie between the tube and the passageway surface. Such fabric tubes may be of assistance when for example synthetic resin is applied to the everting face or to the wall of the passageway (10) in order to anchor the resulting lining to the passageway surface. The present invention has a number of advantages including there is no theoretical length limitation on pipes which can be lined using the extrusion method. Material handling and transport costs can be considerably reduced. By so forming the extrudate into folded form, bends can be negotiated, and the material can be readily everted.

Claims: CLAIMS 1. A method of lining a pipeline or passageway wherein a thermo-plastic lining pipe is extruded on site in a substantially vertical downwards direction into a man-hole and the extruded pipe is guided down the man-hole and into the pipeline or passageway to be lined, whilst the exterior of the extruded lining pip.e is kept warm and the pipe therefore soft by virtue of heating fluid surrounding the extruded lining pipe, and the lining pipe either being extruded in a folded form so that it is of reduced overall dimension enabling it to be passed into the pipeline or passageway, or being folded or formed after extrusion into such reduced size, and the soft, hot and folded extruded lining pipe being expanded, when in the pipeline or passageway, onto the pipeline or passageway surface and eventually being cooled so as to remain in position on such surface. 2. A method according to Claim 1, wherein the extruded lining pipe is applied to the pipeline or passageway surface by being everted onto such surface. 3. A method according to Claim 1, wherein the extruded lining pipe is pulled into position, until it extends for the full length of the pipeline or passageway to be lined, following which it is expanded by introducing fluid under pressure into the interior of the lining pipe eihter directly or by everting an expansion tube into the lining pipe. 4. A method according to any of Claims 1 to 3, wherein the exterior of the extruded lining pipe in addition to being kept warm by means of heated fluid, is also kept under pressure by said fluid in order for example to keep the lining pipe in the said folded condition. 5. A method according to Claim 3, or Claim 4 when dependent upon Claim 3, wherein, to assist in the pulling of the lining pipe into the pipeline or passageway, a pull-rope is fed through the extruder so as to emerge in the centre of the extrudate which, after folding, engages the central rope, and is held suitably thereto by virtue of the friction which arises as a result of pressuring the exterior of the lining pipe by the said heated fluid. 6. A method according to any preceding Claim, wherein the pipe is folded so as to define a star configuration in cross section. 7. A method according to any preceding Claim, wherein the lining pipe comprises p.v.c. or any of the polyole ins. 8. A method according to any preceding Claim, including feeding into the centre of the extruder a fabric tube which forms reinforcement for the interior of the extrudate, and when the extruded tube is eventually everted inside the pipeline or passageway, the reinforcement tube will be presented to the pipeline or passageway surface. 9. A method according to Claim 8, wherein the fabric layer forms a useful anchoring means if the extruded pipe is to be anchored to the pipeline or passageway surface, for example using a curable synthetic resin as adhesive or bending medium.

Inventors: WOOD ERIC, WOOD, ERIC
Applicants: INSITUFORM GROUP LTD, INSITUFORM GROUP LIMITED
Application year: 1991
Main classification: F16L55
IPC codes: F16L55