A METHOD OF RESTORING OR MAKING A CONVEYOR CHANNEL AND A LINING HOSE FOR CARRYING OUT THE METHOD

Abstract: Method of restoring or making a conveyor channel or pipeline for medium under pressure, especially water, along an already existing cavity (1) formed of a section of a damaged and untight conventional pipeline or consisting of recesses in successively arranged elements, preferably of insulating material. The new feature resides in drawing in a hose-like lining (4) including a covering (5) of durable, pressure-absorbing, untight material which is generally unelastic and has no tendency to expand and contract axially but is elastic and expandible to a limited degree in the peripheral sense, said covering (5) including an inner layer (6) which is tight, elastic, soft and resistant to the material being conveyed.

Description: A METHODOFRESTORINGORMAKINGACONVEYORCHANNEL A NDALININGHOSEFORCARRINGOUTTHEMETHOD The present invention relates to a method of resto¬ ring or making a conveyor channel or pipeline for me- diu under pressure, especially water, along an already existing cavity formed of a section of a damaged and 5 untight conventional pipeline or consisting of reces¬ ses in successively arranged elements, preferably of insulating material. From Swedish Patent specifications 337,784 and 337,785 there are already known methods and arrangements _o for drawing linings into pressure-absorbing pipes al¬ ready existing or designed for this purpose. A condition for obtaining a quite satisfactory result with the prior art methods is that the outer pipe has ability to absorb the pressure strains from the lining tube or hose 15 formed of soft material. Due to corrosion, settings in the ground or the like pipelines of metal, plastic material, concrete and the like can have leaks or cracks which can be repaired only if the pipe is dug up and replaced or, alternati- 0 veϊy, is uncovered and repaired in situ. When it is a matter of old pipelines there is often no point in re¬ pairing leaks caused by corrosion but it will be neces¬ sary to dig up and replace the entire section of the pipe where damages have been encountered. It goes with- 5 out saying that such operations wϊl3r become expensive and take much time because, in addition to the direct expenditure in connection with the excavation, the taking up of existing pipes':and laying of new pipes will involve comprehensive ground and restoration work. In pipelines 0 having damages of this type it is not possible to uti¬ lize the methods known from the above— mentioned patent specifications because one cannot be quite sure that the damaged sections of the pipe have the pressure-absorb¬ ing ability required.. If, for example, a pipe fracture "ξHHEATϊr OMPI is the result of settings in the ground a soft lining tube in the fracture zone would not have the necessary support in the radial sense and the lining tube would thus be pressed out through the fracture opening and 5 probably burst when the pipe is subjected to pressure. This can also happen when an unprotected lining tube is introduced for example in an already existing cold-water conduit having internally un-broached, very sharp pipe ends formed when the pipe is cut. When the unprotected . 10. soft lining tube is pulled in or is pressed by the in¬ ternal water pressure against these sharp edges a break is likely to take place through the wall of the lining tube. From DK-PS 139,243 it is previously known to pro- 15 vide untight pipes with a lining by drawing into the pipe a hardenable, expandible hose of plastic material, which may include a reinforcement permitting radial as well as axial expansion, which hose is caused to expand by means of hot, pressurized medium, so that it will 20 bear against the inside of the pipe, and is hardened. Said known hose can be said to float in the cavity for¬ med of the pipe and will thus assume a shape conforming therewith. The hose being designed for flanged conduits is to form a collar over the flanges of the conduit so 25 as to constitute a complementary flange seal. The con¬ dition for this hose to function is that the hose being expanded will meet a moulding wall defining the expan¬ sion. If it is a question of lining a practically in¬ tact pipe no problem will arise but when a break is to 30 be bridged there is a great risk that the hose material will expand in balloon fashion, which can give rise to unacceptable pocket formations in the pipeline and a great risk of hose rupture caused by the edges of the fracture. That hose involves no safe solution of the 35 problems. The object of this invention is to provide a me¬ thod and a hose specifically designed therefor, permit- ting, on one hand, a reliable and unproblematic instal¬ lation of linings in damaged pipes independently of the extension and position of the damages and, on the other hand, a permanent, appropriate flow stream function in the pipe restored according to the method. The object can be considered to include the provision of a fluid passage in an existing cavity with no claim to tight¬ ness and pressure-absorbing ability. The essential characteristic of the method of the invention resides in drawing into the cavity a hose- like lining including a covering of durable, pressure- absorbing, untight material which is generally unelasfeic and has no or insignificant tendency to expand and con¬ tract axially but is elastic and expandible to a li i- ted degree in the peripheral sense, said covering in¬ cluding an inner layer which is tight, elastic, soft and resistant to the material being conveyed. The invention will be described more fully below with reference to the accompanying drawings in which: Fig. 1 shows a schematic cross-section through a pipe or cavity provided with un internal lining accor¬ ding to the invention; Fig. 2 is a cross-sectional view of the lining; Fig. 3 shows a schematic cross-section through a damaged pipe into which a hose according to the inven¬ tion is pulled in; Fig..4 shows a schematic longitudinal section il- lustrating the ability of the internal lining or lining hose to adapt itself and to absorb pressure strains; Fig. 5 is a longitudinal section showing how the lining is drawn in; arid Fig. 6 is a schematic view of a pipe system showing how it can be provided with an inside lining hose. In the drawings, 1 designates a cavity which can be formed of a pipe 2 of metal, plastic material, con¬ crete or the like. The cavity 1 may also be formed of successive holed blocks with ηg claim to tightness, e.g. I. 4 of insulating material of little mechanical stength. The pipe may have a damage for example in the form of a crack, as indicated at 3 in Fig. 2. To provide a passage for the medium to be conveyed through the cavity or conduit a lining in the form of a hose 4 is fitted therein. The lining hose comprises an outer, pressure-absorbing, suitably stocking-like layer 5 and an inner t tight layer 6 which is resistant to the medium to be conveyed. The lining hose is delivered to the place for use in the flattened condition shown in Fig. 2 , which faci¬ litates transport, storage and handling. In principle one might bend up the flattened li¬ ning hose and pull it through the pipe cavity 1, as is indicated with dashed lines in Fig. 1. However, as the friction surface F' facing the cavity wall would thus be¬ come comparatively large and the edge portions would press against the cavity wall due to the intrinsic elas¬ ticity of the lining hose material, it is preferable to inflate the hose so as to assume the shape indicated by full lines, prior to the operation of drawing the hose into suitably insulated cavities with smooth and undamaged walls. The friction surface F* will thereby be reduced and the required pull will become consider- ably lower. As the lining hose is peripherally expandible up to a certain limit and thereupon does not yield one may let it remain inflated during the pulling-in operation only to such a degree that it will assume round shape.' After the lining hose has been connected to couplings, T-pieces or the like arranged at the respective ends of the pipe section it may be set under full pressure ' whereby it expands and fills out, or almost fills out the cavity 1. When a lining tube or hose is to be drawn. into a damaged pipe with a rugged or rough surface it is con¬ venient to roll up the hose 4 and hold it together tern- porarily during the drawing operation, as indicated in Fig. 3. This can be done by attaching around the rolled- up hose adhesive tapes which are strong enough to keep the hose rolled up but burst when the hose is set under pressure. Alternatively, when the hose is rolled up in connection with its introduction at .the end of the ca¬ vity 1 one may wind round it a thin wire or the like ■ attached to the cable by means of which the hose is drawn through the cavity. To the same cable a conical guide sleeve should suitably be attached in which the hose end is inserted and fastened. When the hose is in posi¬ tion the wire is slackened and detached and the guide sleeve is removed whereby the wire can be pulled out and the hose can unfold. When a rolled-up hose is used the friction surface F 1 ' * will be very small. Another advantage is that, as the cross-section of the hose is minimized, it is easy to pass constrictions, if any. The ability of the hose to expand peripherally makes it possible to completely fill out the available space in the pipe. The area of the cavity may be decisive for the hose dimension and the aim is that the hose in fully expanded condition should fill out the cavity area as much as possible. Since the hose is peripherally elastic to a limi¬ ted degree it can function without hindrance even if the cavity should have local constrictions, as indica¬ ted at 7 in Fig. 3. Axially, i.e. in the longitudinal direction of the lining hose, it is unelastic and has no essential ten- : dency to expand and contract, which, for one thing, re¬ duces the strains on the connection points. As the outer layer is pressure-absorbing the hose ' can also without problems be allowed to pass fractures and cracks in the pipe and the only condition for this is that the fracture must not be such that the cavity cross-section is entirely obstructed by sunk pipe wall portions or penetrating ground material. A moderate lo¬ cal reduction of the cavity cross-section, which does not prevent introduction of the hose, has no appreci- able influence on the conveying ability of the pipe. Even if part of a pipeline has fallen out entirely, for example because underlying ground material has sunk, the conveying ability of the pipeline can be rapidly re¬ stored by-uncovering the fracture ends and pulling the lining hose, which has been drawn into the pipe part on one side of the rupture, freely over the rupture so as to bridge it, passing the hose into the pipe part on the other side and pulling it on through this part up to the following joint. In order to prevent the lining hose from being compressed by the filling material it should be set under pressure before the excavation is refilled. The outer layer of the lining hose can be made up of woven polyester yarn, for example, which gives the required strength and low friction against the cavity wall. The inner " layer is suitably made up of a rubber composition which is decided with regard to the nature of the medium to be conveyed. To facilitate pulling of the lining hose 4 into the cavity 1 the front plug 8 of the two plugs required to enable inflation, i.e. the plug situated at the front end of the lining hose and is connected to the drawing cable L, may be provided with exhaust openings 9 direc¬ ted in backward direction, i.e. towards the rear end of the hose. As part of the pressure medium keeping the lining hose inflated is allowed to flow out in backward direction an assisting pull is obtained at the same time as the outflowing medium acts as a friction-reducing lubricant. New pressure medium, replacing the discharged medium, is preferably continuously supplied through a connection 11 to the plug 12 arranged in the rear end of the lining hose. u> i to to H P * tn o tn o tn o tn that the lining hose will run freely over a short sec¬ tion. The invention must not be limited to that descri¬ bed above and shown in the drawings but may be modified in various ways within the scope of the appended claims.

Claims: CLAIMS 1. A method of restoring or making a conveyor chan¬ nel or pipeline for medium under pressure, especially water, along an already existing cavity (1) formed of a section of a damaged and untight conventional pipe- line or consisting of recesses in successively arranged elements, preferably of insulating material, c h a r a c t e r i z e d by the step of drawing in¬ to the cavity (1) a hose-like lining (4) including a* covering (5) of durable, pressure-absorbing, untight material which is generally unelastic and has ho or in¬ significant tendency to expand and contract axially but is elastic and expandible to a limited degree in the peripheral sense, said covering (5) including an inner layer (6) which is tight, elastic, soft and resistant to the material being conveyed. 2. A method as claimed in claim 1, c h a r a c ¬ t e r i z e d in that the hose-like lining (4) , the form of which is flattened in uninfluenced condition, is given a generally circular shape prior to the draw- ing-in operation. 3. A method as claimed in claim 2, c h a r a c ¬ t e r i z e d in that the hose-like lining prior to the drawing-in operation is provided with end plugs ■ and is inflated to assume circular shape. 4. A method as claimed in claim 3, c h a r a c ¬ t e r i z e d in that the plug fitted in the front end of the hose-like lining is provided with outlet ope¬ nings, directed opposite the drawing-in direction, for pressure medium facilitating said drawing-in operation. 5. A method as claimed in claim 1, c h a r a c ¬ t e r i z e d in that the hose-like lining prior to the drawing-in operation is rolled or folded up in its longitudinal direction and suitably is provided with means holding it together. which are active during the drawing-in operation. OMPI 6. A lining hose for carrying out the method as claimed in claim 1, c h a r a c t e r i z e d in that the lining hose consists of a covering (5) of dur¬ able, pressure-absorbing, untight material which is ge- nerally unelastic and has no or insignificant tendency to expand and contract in its longitudinal direction and is elastic and expandible to a predetermined limit in the -peripheral sense, said covering (5) including an inner layer (6) which is tight, elastic, soft and resistant to the material being conveyed through the lining hose.

Inventors: WOLFF INGEMAR, WOLFF, INGEMAR
Applicants: FORSHEDA INNOVATION AB
Application year: 1983
Main classification: F16L55
IPC codes: B29C63, F16L55