EP0000576B1

EP0000576B1 - Method of lining a passageway

Info

Publication number: EP0000576B1
Application number: EP19780100492
Authority: EP
Inventors: Bernard Barber
Original assignee: Trio Engineering Ltd
Current assignee: Trio Engineering Ltd
Priority date: 1977-07-27
Filing date: 1978-07-24
Publication date: 1981-09-02
Also published as: DK332478A; AT374901B; ES472063A1; CA1115917A; AU3837378A; EP0000576A1; DE2861006D1; ATA547678A; AU529673B2; IE47216B1; NO782548L; IE781512L; US4207130A; JPS55133923A

Description

This invention relates to the lining of passageways, especially long underground pasageways, such as sewers and pipelines.
There have been many proposals for the lining of passageways because throughout the world there is a very large number of passageways in need of repair and/or restoration. Passageways may need repair because of a number of reasons. For example an underground sewer may be leaking to such an extent that sewage is leaking into the surrounding subsoil or a pipeline may be leaking to such an extent that ground water and other liquid deposits are leaking through the pipeline into the interior of the pipeline, which may be carrying a medium which is becoming contaminated by the ingressing liquid. Again, the passageways may require repairs where they are not actually leaking, but are corroding or eroding, which could lead to leakage. Still further, it may be required to line a passageway in order to change its function e.g. it may be desired to line an otherwise corrosive passageway with an anti-corrosive liner, to enable that passageway to carry corrosive material, or it may be desirable to insert a liner in order to enable the passageway to carry medium under pressure, the liner providing a means of supporting or assisting in supporting the pressure forces of the pressure medium.
It will be appreciated that depending upon requirements, liners for pipelines vary from thin, flimsy forms of plastics foil where a surface is simply to be protected from an environment, to heavy resin impregnated felts where the liner is to support the pressure of the medium flowing in the passageway and to protect the passageway surface from chemical attack and impacts from objects and debris being carried by the medium.
In French specification 2,316,528 there is disclosed a method of lining pipeline, wherein a circular liner is deflected to out of circular condition so that it becomes small enough to be inserted in the pipeline, and is held in such condition by bands or a sheath. The so held liner is inserted in the pipeline and when in the pipeline pressure can be used to break the band or sheath allowing the liner to return to circular condition lining the pipeline. The liner is described as including circumferential reinforcement in the form of elastic threads or filaments to assist in expanding the liner back to the circular condition. In French specification 2,327,484 there is described a method of lining a passageway wherein a flexible liner is impregnated with a resin. The flexible liner in flat condition is introduced into the pipeline, whilst floating it on liquid in the pipeline, and then is inflated so as to shape to the pipeline surface, and the resin cures so that the liner will remain in position.
In all of the known systems for passageways lining there is a common problem of inserting long length linings over 305 metres into a pipeline without having to provide the linings in sections and having to provide many joints which can be a source of leakage. The problem of providing sealed jointing with the heavier gauge liners has not fully been solved for cases where the passageway carries a fluid, such as gas under pressure.
It is possible to insert long lengths of flimsy material into passageways by everting it thereinto, but such liners cannot be used to increase the pressure containing capability of the passageway.
Heavy, resin impregnated felt liners must of necessity be of finite length as otherwise they become impossible to handle.
There is, therefore, a real need to provide a method of lining passageways with a liner which can be made in long lengths, and is robust enough to contain fluid under pressure.
The present invention deals with this need and in accordance with the invention there is provided a method of lining a passageway with a tubular liner of plastics, said tube being of such resiliency that it can be flexed but will return or tend to return to the unflexed conditon, comprising deflecting the tube to a condition in which the largest diametrical dimension of the deflected tube is less than the outer diameter of the undeflected tube, releasably holding the tube in its deflected condition, inserting the held, deflected tube into the passageway to be lined, and releasing the hold on the tube when the tube is in the pasageway and either allowing or causing the tube to return to its original undeflected diametrical condition characterised in that the tubular liner of plastics is formed by being extruded from an extrusion machine located at the site of the passageway.
The extruding, deflecting, holding and inserting the tube in the passageway preferably is effected in a continuous operation.
After the tube has been placed in the passageway and the holding means released, the interior of the tube may be pressurised in order fully to redeflect the tube to the circular form, or such operation may be effected by passing a pipeline pig through the tube.
The tube may be deflected to horse-shoe shape in cross section and the holding means may be a tape or sleeve of plastics foil. In the case of a tape it may be applied to the tube with adhesive and be such as to be releasable by peeling the tape from the tube. Where a sleeve is used it may have a seam of weakening which can be ruptured, for example by igniting a fuse embodied therein along such seam.
After the tube is extruded and whilst still soft. it may be expanded up to the required size before being deflected.
If it is desired to provide a liner in the pasageway which has a higher hoop stress than a single extrudate, the process of the invention can be repeated a number of times, each subsequent extrudate being inserted in the previous extrudate, until a liner of the desired thickness is formed.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein:-

Fig. 1 is a perspective view of apparatus for carrying out the method of the invention;
_.Fig. 2 is a sectional view showing the tubular extrudate in the deflected condition;
Fig. 3 is a view similar to Fig. 2, showing how a number of extrudates may be placed one within another;
Fig. 4 shows how the method is carried out in lining a passageway in the form of an underground pipeline; and
Fig. 5 is a sectional side view showing how the end of the tubular extrudate may be anchored when positioned in the passageway.

Referring to the drawings, and firstly to Fig. 1, reference 10 indicates a conventional extruder for producing a tubular plastics material extrudate 12. The extrudate is shown as passing through spray bars 14 from which cold water is sprayed onto the extrudate in order that the plastics material will set, and from the spray bars, the plastics material tube passes through a forming apparatus 15, comprising a deflecting roller 16 carried by a frame 18, and folding rollers 20. The deflecting roller 16 deflects the upper central portion of the tube which is semi-rigid so that it takes up a horse-shoe type configuration in cross section as shown, in Fig. 2 and the rollers 20, which are waisted as shown press the sides of the horse-shoe cross section together. A driving roller 22 drives and supports the tube 12. Said roller 22 is driven by a motor 34.
As the thus deflected tube 12 proceeds from the deflecting apparatus 15, it is wrapped with a plastics foil or fabric 24 which may be of polyvinyl chloride and is wrapped around the tube 12 as shown so that the edges thereof overlap at a hot melt bonder unit 26, and such edges are sealed in order to form a sleeve around the deflected 12 to hold it in the deflected condition. Along the seam there is inserted a fuse wire 28 which is supplied from a fuse supply reel 30. The purpose of the fuse wire will become clear hereinafter.
Referring now to Fig. 4, the thus deflected tube 12, held in deflected condition by the foil or fabric 24 is fed directly into a passageway 35 to be lined with the material of tube 12. Insertion into the passageway 35 is facilitated by virtue of the fact that the tube 12 is held in deflected condition and in this condition the largest diametral dimension of the tube 12 is less than the outer diameter of the tube prior to deflection and is smaller than the inner diameter of the passageway to be lined. In Fig. 4 the free end of the tube 12 is shown as being connected to a pulling member 37 in the form of a rope, and additionally the tube 12 is shown as being led through a lead-in pipe 36 and out of a tail pipe 38. The pipes 36 and 38 are connected to the ends of the underground pipeline 35 in a watertight manner, and in fact the passageway 35 and the pipes 36 and 38 are flooded with water in order to facilitate travel of the tube 12 through the passageway 35. When the tube 12 is in position, the water can be removed from the passageway, but it may be desirable to introduce a lubricant into the water, such as a soap composition in order that the tube 12 which in itself is reasonably bendable, can easily follow beds in the passageway 35. This applies especially in the case where the passageway is prelined with a thin film of plastics material such as polythene film. The free end of the tube 12 may be sealed in order that the interior of the pipe does not become flooded with water, although in some instances it is desirable that this should happen. It is desirable that the tube 12, which may have to travel long lengths, e.g. over 1,000 ft. should have as near neutral buoyancy in any liquid contained in the passageway 35, as otherwise there could be substantial drag forces exerted on the tubes as it is inserted into the pipeline.
The process up to the stage of placement of the lining tube 12 in the pipeline passageways 35, is continuous, which provides for minimum operation time, but if the extruder can be stopped and started satisfactorily, the process can be operated on a step by step basis.
When the tube 12 is in position, the holding effect of the sleeve 24 is released, and in this example this is achieved by igniting the fuse 28 which ruptures the sleeve 24, and allows the deflected tube 12 once more to expand to the circular condition and into a position lining the interior of the passageway 35. The return of the tube 12 to circular form may be assisted by pressurising the interior of the' tube 12 with fluid under pressure as by passing a pipeline pig therethrough from end to end.
In relation to the passageway or pipeline to be lined, the lining tube 12 may be of slightly larger diameter or smaller diameter than that of the passageway or pipeline. when the tube 12 is of slightly larger diameter, when it returns to its circular form in the passageway or pipe line it snaps into position and in so doing becomes circumferentially compressed in that it is prevented from taking up its natural size. When the lining tube 12 is sized to snap into a circumferentially stressed condition as described, it is preferably only slightly larger diameter than the pipeline or passageway to ensure that the tube 12 does snap into circular form. This arrangement is useful when the lining operationis to provide for example a liquid impermeable barrier rather than a stress taking member.
When the tube 12 is sized to be of smaller diameter than the pipeline or passageway surface to be lined, it may be only slightly smaller or significantly smaller. One may arrange for the lining diameter to be slightly smaller than the passageway or pipeline surface where the lining tube has to carry fluid under pressure and must expand under the said pressure, and thereby contribute to taking a certain amount or all of the hoop stress in order to contain the fluid.
When the tube 12 is of significantly less diameter than the pipeline or passageway the fold in the tube 12 as formed by rollers 16, 20 may be filled with a filling material such as mastic which spreads round the tube to fill the clearance between the tube 12 and pipeline or passageway surface, when the hold on the deflected tube 12 is released.
In the case where the liner has to be sufficiently strong to contain pressure forces when fluid medium under pressure passes through the passageway, the process as described in relation to Fig. 4, can be repeated, each subsequent extrudate being placed inside the previous extrudate in the manner described, and so that there is a small peripheral clearance between each lining tube and the inner surface of the tube in which it is located. Fig. 3 shows how a number of extrudates have been positioned one within the other, and also shows a final extrudate whilst still held in the deflected condition, inside the previous extrudate and ready to be expanded back to its original circular form. By this reptition of the process, a liner of any desired thickness and hoop strength within limits can be built up.
It would not be possible to insert a single liner of the same overall thickness as a number of extrudates, because it would be extremely difficult to deflect such a one-piece liner to make it smaller in overall dimensions than the passageway, and it would not bend longitudinally to pass through the pipes 36 and 38 and any other bends in the passageway 35.
The invention is particularly suitable for pipelines and passageways which are neither too small nor too large. For very large passageways, i.e. ones in which human beings can freely walk or move, other lining techniques can be used, because there is not the same difficulty in the creation of joints between sections of liner, and for very small pipelines, it becomes extremely difficult to deflect the tubular member 12 down to a smaller size for insertion in the pipeline and the frictional forces created by endeavouring to direct a deflected tube around bends and curves become prohibitive. The invention can however be used over a wide range of passageway sizes for example from pipelines of the order of 4 or 5 inches diameter up to passageways of the order of 4 to 5 feet.
The final size of the tube 12 as it is extruded from the extruder 10 is established before the material is set and there may be a means for causing the extrudate to inflate up to the desired size whilst it is still soft. It will be necessary of course to reduce the size of subsequent extrudates when a multilayer lining tube is being built up, such as in the arrangement shown in Fig. 3.
The tubular extrudate may be formed of any suitable material such as polypropylene, high density polyethene or similar plastics material which has a significant plastic memory, and preferably is of a thickness to give the required flexing and recovery characteristics. Polypropylene of a thickness 3 mm of (g") appears to give satisfactory characteristics in this respect.
One method releasing the hold on the extrudate when in deflected condition in the passageway has been described, i.e. the use of a fuse, but other methods may be adopted. For example the holding means may be severed by a cutting means, or it may be in the form of a tape which extends lengthwise of the tube and which is adhesively applied to the tube 12, but can be peeled therefrom, or it may be provided with a line of weakening which is fractured as a result of pressurisation of the interior of the tube 12 after it has been placed in position. In a further arrangement the holding effect is achieved by wrapping a web around the deflected tube in much the same manner as indicated in Fig. 1, but the adjacent edges of the web are held together by a running stitch arrangement sewn into the edges as they are brought together the entire seam being releasable by pulling on the thread at one end of the assembly comprising inner tube and outer web. Pulling on such thread causes the stitching to release along the entire length of the seam. An alternative holding arrangement comprises a mandrel of appropriate shape and having ducting whereby, when the tube is over the mandrel, and source of negative pressure is applied to the ducting, the tube is sucked onto the mandrel, and in being so sucked, the sectional shape changes such that the largest diametral dimension is less than that of the tube before deflection. The tube is so held until it has been fully inserted in the passageway when the source of negative pressure is released and air under pressure is supplied to the tube thereby inflating the tube to its original form. In any event, after the hold of the holding means has been released, the tube 12 will tend to return to its initial undeflected condition, but to ensure that it does it may be desirable to pressurise the interior of the tube 12 or to pass a pipeline pig therethrough. If the tube 12 is of slightly larger diameter than the internal diameter of the passageway 35, it will finally be placed in position by a snapping action which results in the liner tube being placed in compression, as described herein. Where a mutli-layered liner is built up, it can be arranged that each subsequent extrudate is snapped into the previous extrudate in the manner described above.
Referring finally to Fig. 5, in this drawing there is shown an arrangement illustrating how the end of the liner may be anchored by the use of complimentary wedging collars. An outer frusto-conical collar 40 is bolted to the end of the pipeline 35 and the free end of the liner 12 overhangs the bolt joint by an amount equal to the length of the collar 40. A male collar 42 having a frusto-conical outer surface is inserted into the free end of the liner 12 such that bolt holes in flanges of collars 40 and 42 become aligned and bolts are passed therethrough and tightened with the effect that the free end of the lining tube 12 becomes trapped and wedged between the frusto-conical faces of the two collars 40 and 42. Other arrangements for fixing the ends of the lining tube can of course be used.
The invention also provides a passageway lined in accordance with the method.

Claims

1. A method of lining a passageway with a tubular liner of plastics, said tube being of such resiliency that it can be flexed but will return or tend to return to the unflexed condition, comprising deflecting the tube to a condition in which the largest diametrical dimension of the deflected tube is less than the outer diameter of the undeflected tube, releasably holding the tube in its deflected condition, inserting the held, deflected tube into the passageway to be lined, and releasing the hold on the tube when the tube is in the passageway and either allowing or causing the tube to return to its original undeflected diametrical condition characterised in that the tubular liner of plastics is formed by being extruded from an extrusion machine located at the site of the passageway.

2. A method according to claim 1, wherein the extruding, deflecting, holding and inserting of the tube is performed as a continuous operation.

3. The method according to claims 1 or 2 wherein the deflecting is performed by passing the extrudate past forming rollers, which deflect the tube into horse-shoe shaped section.

4. The method according to claim 3, wherein the tube is of slightly larger diameter than the pipeline or passageway to be lined, so that it snaps into position lining the pipeline or passageway when it returns or is returned to its initial condition.

5. The method according to claim 3, wherein the tube is slightly smaller in diameter than the passageway or pipeline surface to be lined.

6. The method according to Claim 5 wherein the deflected portion of the tube is filled with a grouting material such as mastic which fills the clearance between the outside of the tube and the pipeline or passageway surface when the tube returns or is returned to its initial condition.

7. The method according to any preceding claim wherein the tube is held in deflected condition by a sleeve formed by wrapping a web around the deflected tube and by joining the meeting edges of the web to form a seam extending longitudinally of the tube.

8. The method according to Claim 7 wherein the said seam is provided with a fuse wire, the ignition of which effects the splitting of the seam and the release of the hold on the deflected tube.

9. The method according to Claim 7 wherein the sleeve has a line of weakening extending for the length thereof, and release of the hold on the tube is effected by pressurising the interior of the tube which bursts the sleeve along the line of weakening.

10. The method according to any of Claims 3 to 6, wherein the tube is held in deflected condition by adhesive tape extending lengthwise of the tube, and the hold on the tube is removed by removal of the said tape.

11. The method according to Claim 1 wherein the tube is held in deflected condition by a shaped mandrel having ducts therein and over which mandrel the tube is placed and deflection is achieved by applying a vacuum to said ducts to draw the tube onto the mandrel surface.

12. The method according to any preceding claim wherein the pipeline or passageway is flooded with a liquid which fills the tubs as it moves into the pipeline or passageway and by which the held tube is buoyantly supported as it is inserted into the pipeline or passageway.

13. A method according to claim 12, wherein the liquid contains soap to act as a lubricant.

14. The method according to any preceding claim, when repeated to insert a first tube in the pipeline or passageway and to insert subsequent tubes of progressively smaller dimension within the first tube, the second tube, the third tube and so on, until a laminated lining tube of a required thickness is achieved.

15. The method according to any preceding cliam wherein the or each tube is of polypropylene or high density polythene or similar plastics material which as a plastic memory and is of a thickness of the order of 3 mm {f').