GB2192442A

GB2192442A - Lining a duct

Info

Publication number: GB2192442A
Application number: GB8616899A
Authority: GB
Inventors: Hunter Martin Franklin
Original assignee: Stanley Robert Moore
Current assignee: Stanley Robert Moore
Priority date: 1986-07-11
Filing date: 1986-07-11
Publication date: 1988-01-13
Also published as: GB8616899D0

Abstract

A portion 9 of a pig or carrier 7 is rotatable above a longitudinal axis and carries a scissors-type extendible linkage 10 having a platform 11. By rotation of the portion 9, displacement of the carrier 7, and extension of the linkage 10, service means eg. an inflatable plug 15 or cutter 31 on the platform 11 can be maneouvred to be located in a branch conduit 2. The plug 15 includes a metallic part (eg ring 16, Figure 3 not shown) which a metal detector can detect through a lining (Figures 4,5 not shown) which is fitted in a main 1 to determine the position at which a port has to be cut in the lining to coincide with the branch conduit 2. The plug 15 may be provided with a spring-loaded extension (16a, Figure 5) to facilitate detection when a lining (21) spaced a larger distance from the wall of the main 1 is used. <IMAGE>

Description

SPECIFICATION A method of lining a fluid conduit, apparatus for use in said method and a carrier for use in a fluid conduit Technical field and background art The present invention relates to a method of lining a fluid conduit, apparatus for use in such a method, and a carrier which is displaceable within a fluid con duitforservicing purposes therein. The invention was primarily developed for lining,with a tubular liner, a main fluid conduit (such as a sewer, water, gasorotherfluid pipe) having a branch conduit or pipe extending therefrom. The tubular linerwill usu- ally be a plastics pipe which is pulled through the main fluid conduit.With the liner positioned in the main fluid conduit it is necessary to form ports in the liner by cutting through the wall thereof at positions which coincide with respective branch conduits or piper so that fluid flow is permissible between the branch conduit and the bore ofthe liner. The cutting of a port in the liner may be achieved by a water jet cutting device mounted on a carrier within the liner in accordance with the disclosure in our British Patent No. 2,098,300B. Prior to the ports being cut, it is of course necessary to locate, with reasonable ac curacy,the respective openings from the main fluid conduit to the branch conduits or pipes so thatwhen the ports are cuttheywill substantially coincide with their respective branch conduits.With relatively thick walled and substantially rigid plastics liners it will be appreciated that location of an appropriate position for a port visually (for example, by use of a television camera mounted on a carrier within the liner) cannot be relied on. As a consequence,-prior proposals to locate position at which a port should be cut in the liner for a buried sewer pipe include excavation techniques where a branch conduit is broken open to mark the wall of the linerthrough the opening of the branch conduit so that such marking is detectable from the interior of the liner and subsequently repairing the branch conduit.Afurther proposal is to position a radioactive source in the branch conduit, either by excavating and breaking through the wall ofthe branch conduit or by manoeuvring the source through the branch conduit from the end thereof remote from the main conduit and then detecting the position of the radioactive source and thereby the branch conduit from within the liner. It will be appreciated thatthe prior proposals for determining the port locations in the liner can prove expensive, lengthy and often inconvenient and-it is an object of the present-invention to alleviate the disadvantages associated with such prior proposals. It is also an obect of the present invention to provide an apparatus which can be used to determine, with reasonable accuracy, the location at which a port should be cut within a liner.Afurther object is to provide a carrier which can be used withinafluidconduittofacilitatepositioningofa particular service on that carrier.

Statements of invention and advantages According to the present invention there is provided a method of lining a main fluid conduit having a branch conduit which comprises positioning within the branch conduit a locating means having an extendible part, extending said extendible part to retain said locating means in engagement with the branch conduit; providing within the main fluid conduit a tubular liner; insertingwithinthetubularlinerdet- ecting means which is responsive to said locating means and manoeuvring said detecting means to locate said locating means and from said location cutting through the liner wall from within the linerto form a portwhich substantially coincides with the branch conduit It is preferred that by said method the locating means is positioned within the branch conduit by insertion therein from a position within the main fluid conduit. It is also preferred thatthe extendible part is extendible by means from within the main fluid conduit.

Further according to the present invention there is provided apparatus for use in the method as speci fied-in the immediately preceding paragraph which comprises a carrier displaceable longitudinally within the main fluid conduit and carrying the locating means; displacement means for displacing the locating means laterally relative to the carrier to position the locating means within the branch conduit, and means for extending the extendible part of the locating means for retaining the locating means in engagementwith the branch conduit.

Still further according to the present invention there is provided a main fluid conduit having a lining provided by the method as specified in the preceding penultimate paragraph.

The invention also provides a carrierfordisplace mentlongitudinallyalongafluidconduitandwhich carrier comprises a body part; a portion on said body part mounted for rotation relative thereto about a longitudinal axis; drive means for controlling rotation of said portion; laterally extendible displacement means mounted on said portion ofthe carrier for carrying service means, and meansforcontrolling lateral displacement ofthe displacement means so that, by controlled longitudinal displacement of the carrier, rotation of said portion and lateral displacement of the displacement means, such service means as may be carried bythe displacement means can be manoeuvred to a desired position relative to said fluid conduit.The service means which may be carried on the displacement means of the carrier may comprise a locating means as afote- mentioned which isto be inserted in a branch conduit bythe method ofthe present invention; alterna tively,theservice means maycompriseacutter device such as a water jet cutter as may be required to be inserted into the bore of a branch conduitfrom the main fluid conduit for the purpose of cutting the wall of that branch conduit.As a further possibility the service means may be in the form of a seal or plug which is required to be inserted within the branch conduit (for example, the seal may comprise a chamber which isto be expanded underfluid pressure within the branch conduit to provide a seal between that conduit and a port in a plastics liner in accordance with the teaching of our copending British Patent Application No. filed on even date with the presentApplication).

By the proposal for providing a lining a main fluid conduit in accordance with the present invention it is envisaged that, prior to the liner being positioned withinthe main conduit, a locating means will be positioned in the or each branch conduit, preferably by insertion of the locating meansfrom the main conduit into the branch conduit by use of a carrier as mentioned above. With the locating means appropriately positioned within the branch conduit, the extendible part of that means is extended to abut and retain the locating means within the branch conduit.

Prnferablythe extendible part ofthe locating means is extendible by the admission of fluid under pressure into an expandable chamberthereof. Thefluid which is admitted intothe expandable chamber is preferably air but may be a liquid. The fluid will usually be admitted by way of anon-retu rn valve from a hose on the carrier.It is preferred that the hose through which fluid is admitted to the expandable chamber of the locating means is automatically det achablefromsuch means when the extendible part is adequately expanded to be firmly retained in the branch conduit; this latter detachment is conveni entlyachieved bythe hose "blowing-off" from a non-return valve or nozzle on the locating means so that the after can be isolated in the branch conduit.

Preferably the expandable chamber of the locating means is toroidal such as an elastomeric innertube of a vehicle tyre. The locating means will comprise a source to which the detecting means is responsive.

This source may be radioactive. However, because ofthe hazards ge#nerally attributed to the use of radioactive sources, it is preferred that the source on the locating means is of a generally passive nature,for example a metal body which is capable of being sensed by a metal detectorwithin the liner. Afurther possibility is fdrthe source to be a magnetwhich may be appropriately detected from within the liner.

Preferablythe locating means as a whole is generallytubular orcomprisesfluidflow passages so that whenfittedwithinthebranchconduittfluidflow communication is maintained from the branch conduitthrough the locating means to the main fluid conduit; in th is way it is possible for locating means to be positioned within the branch conduits well ahead of the time at which the main conduit is fitted with its liner so that, untilthe latter occurs,fluidflow is permitted through thebranch conduits without interruption to the users ofthose conduits.

For the purpose of manoeuvring the locating means to position such means in the branch conduit it is preferredthatthedisplacementmeanswhich carries the locating means on the carrier can be rotated about the longitudinal axis along which the carrierwill be displaceable within the main fluid conduit so that by appropriate rotation and longitudinaldis- placement ofthe displacement means, the locating means can be aligned with a branch conduit opening positioned around the fluid conduit (bearing in mind that, in sewers, branch conduits are usually found in the upper 3006 arc ofthe peripheral wall ofthesewer).The displacement means may be of any convenientlaterallyextendibleform such asascissors- type linkage, a fluid pressure operated ram or a lever and gearsystem on which the locating means may be detachably carried or on which another service means may be carried.

Following the positioning of the locating means and liner, a carrier with an appropriate detecting means for sensing the locating means will bedisplaced longitudinally within the liner and the detecting means manoeuvred longitudinally and by rotation (forexampleinasimilarmannertothatinwhichthe locating means may be manoeuvred during its insertion into the branch conduit) until a maximum signal is sensed from the locating means which is-indica- tive thatthe position of the locating means and thereby the branch conduit has been determined.In this position,the wall of the liner may be app- ropriately marked internallyforsubsequent cutting orthedetecting means may haveassociatedthere with a rotary cutter similarto that disclosed in our British Patent No. 2,098,300B with particular refer ence to Figure 4thereof. Following the determination and cutting of a port in the liner, the locating means is preferably removed from the branch pipe especially if the locating means blocks the branch pipe.Where the locating means includes a chamber which is expandable under fluid pressure, such means may be removed, during or following the cut ting ofthe port, by bursting the chamberto reduce the overall size of the locating means and allowing the locating means to fall through the port into the bore ofthe liner. Convenientlythe chamber is burst by cutting# through the wall ofthat chamber with water cutting jets, possibly simultaneously with the cutting ofthe port in the liner.

If it is likely thatthe wall of the liner will be at a considerable spacing from the position ofthe locating means within the branch conduit, then the source which is to be detected on the locating means can be supported, for example by spring means which project into the main fluid conduit, so that such source is nearertothewall ofthe liner-thereby facilitating its detection. The spring means by which the source may be carried as aforementioned if a convenient means of permitting the source to be def lected temporarily should it prove necessaryto fac ilitate the manoeuvring of the liner along the main fluid conduit.

The carrier is conveniently in the form of a sledge although it may be mounted on other forms of runners, rollers or wheels to be pulled in controlled manner by a hawser or otherwise driven through the tubular lining.

The present invention was primarily developed for use in connection with sewer conduits or pipes, how ever, it will be realised that it may be used with advantage in connection with otherfluid conduits such as gas or water piping.

Drawings Embodiments ofthe present invention will now be described by way of example only, with reference to the accompanying illustrative drawings in which: Figure 7 is a longitudinal section through a main -sewer pipe having a branch pipe extending therefrom and which illustrates a known means for cut -ting away an internal projection of the branch pipe; Figure2 is a similar section to that shown-in Figure 1 and illustrates a carrier in the main sewer positioning a locating means within the branch pipe; -Figure 3 is a perspective view, in part section, of the locating means which is positioned in the branch pipe as shown in Figure 2;; Figure 4 is a similar section to that of Figu re 2 and shows the main sewer pipe fitted with a liner and a port being cut in the linerto coincide with the branch pipe; Figure5is#a longitudinal section through a main sewer pipe and branch pipe an#d illustrates a modified form of locating means having a detectable source carried to be positioned adjacent to a re latively small diameter liner within the main sewer, and Figure 8 is a longitudinal section through a main sewer pipe and branch pipe and illustrates a modified form of carrier having a cutter mounted on displacement means ofthe carrierforthe purpose of positioning the cutter within the branch pipe for cutting through the wall thereof.

Detailed description of drawings A conventional sewer pipe 1 has extending therefrom a branch pipe 2. In Figure 1 the branch pipe 2 has a part 2a which projects into the main sewer 1 to form an obstruction. The sewer 1 is to be provided with-a tubular plastics liner and preparatory to the fitting of this liner, the projection 2a is removed by water cutting jets 4 on a known form of carrier 5 which is displaced longitudinally th rough the main sewer 1 under control of hawsers 6 in accordance with the disclosure in our British Patent No.

2,098,300B.

Following removal of obstructions from the mainpipe 1 and priorto the po#sitioning of the plastics liner therein, a carrier 7 is located within the pipe 1. The carrier 7 is similar in many respects to the carrier 5, being displaceable along the pipe 1 under control of forwardly and aftwardly extending hawsers 6 and having sledge-type base runners 8. The carrier 7 has a portion 9 which extends forwardly of its main body and on which is mounted a scissors-type extendible linkage 10 carrying a platform 11. The linkage 10 is extendible and contractibleto displace the platform 11 laterally upon rotation of a screw rod 12 in the appropriate direction by an electric motor (not shown) within the main body ofthe carrier 7.The portion 9 is rotatable (preferablythrough 300#to 360 ) under control of an electric motor (not shown) in the main body of the carrier 7 about the longitudinal axis along which the carrier is displaceable.

Consequently by appropriate control of the hawsers 6 and rotation of the portion 9, the platform 11 can be manoeuvred into lateral alignment orto coincide -with the opening in the wall of the pipe 1 to the branch pipe 2. The aforementioned control will usually be achieved remotely in the manner discussed in our previously mentioned British Patent and under observation from a television camera 13 mounted with lights 14 on the carrier 7 (conveniently for rotation in unison with the portion 9).

Carried on the platform ills a generally annular locating device 15 which is best seen in Figure 3. The device 15 comprises a steel ring 16 having a generally concave ortrough-shaped outer surface 17 on which is seated an elastomerictube 18(similartothe manner in which a vehicle wheel innertube is mounted on the rim of a conventional wheel hub). The tube 18 has a nozzle 19 which includes a conventional form of non-return valve such as a Schrodertype valve through which the tube is inflatable on the ring 16.

The locating device 15 isto be positioned in isolation within the branch pipe 2 as shown in Figure 2.

With this in mind the device 15 is removably mounted on the platform 11 with its tube 18 deflated,the scissors linkage 10 contracted, and with the carrier 7 locatedata convenient access position within the pipe 1. When the device 15 is mounted on the platform 11 a hose 20 from the carrier is fitted to the nozzle 19forth purpose of inflating the tube 18with air under pressure. With the linkage 10 contracted as aforementioned,the carrier 7is moved thrnugh the sewer 1 and the platform 11 then manoeuvred (by rotation of the portion 9, operation ofthe linkage 10 and bythe hawsers 6) under observation from the television camera 13 so that the device 15 displa- ced to be inserted into the branch pipe 2.In this latter position the tube 18 is inflated to abut the side wall of the pipe 2 and be retained within the branch pipe.

The linkage 10 is now contracted to withdraw the platform 11 from the device 15 as the latter is held in the branch pipe. The locating device 15 may be adequately retained on the platform 11 during the aforementioned manoeuvres by temporary retaining means, such as spring devices, brackets, or other means on the platform which may engage with the ring 16 but will readily dis-engagefromthe ring 16upon withdrawal of the platform 11 from the device 15 as the latter is firmly held within the branch pipe.

The hose 20 is also removed from the nozzle 19to isolate the locating device 15 within the branch pipe 2, preferably by the hose automatically blowing-off from the nozzle 19when the tube-1 8 has been inflated to a predetermined pressure (although the hose may be pulled from the nozzle as the carrier 7 is displaced along the main pipe 1 away from the branch pipe 2).

Atubularplastics liner or sleeve 21 is now posi tioned within the main sewer pipe 1 this closes the opening between the main and branch pipes. It is therefore necessary to cut an appropriately located port in thewall of the liner 21 to coincidewith the branch pipe and consequently to detect the appropriate position for cutting the port. This is achieved by utilising the steel ring 16 of the locating device as a sourcefora metal detector 22 mounted on a carrier 23which is displaceable through the bore of the liner 21 in a similar mannerto the carriers 5 and 7. The detector 22 is mounted on a portion 24 of the carrier 23 which is similarly rotatable to the portion 9 of the carrier 7so that the metal detector 22 can be rotated and manoeuvred longitudinally under control of the hawsers 6 until the strongest signal is achieved from the metal ring source 16 in the branch pipe 2. In this position the detector 22 should be directed towards the branch pipe 2 and a laterally directed rotating nozzle 25 on the carrier portion 24 forwaterlet cut- ting (inasimilarmannertothatdiscussedinourBrit- ish Patent No. 2,098,300B with reference to Figure4 thereof) is actuated to cut a port 26 in the linerto -coincide with the branch pipe 2.During the cutting of the port 26, the water jet may pierce and thereby def latethe tube 1 8 so that u pon completion of the port cutting, the steel ring 16 ofthe locating device together with the burst tube 18 may fall into the bore of the liner 21 from which it can be removed. The cutter and detector are not necessarily mounted on the same carrier and, for example, a carrier with a detector cam merely locate and mark the position at which a port is to be cutwhile a further carrier with a - cutter is subsequently used to locate the mark and cut the port.

When the port 26 has been completed, any space which is formed between the wall of the liner 21 and that of the main sewer pipe 1 can be filled with grout ing 27 in the manner discussed in our co-pending British PatentApplication No. filed on even date with the present Application.

In the modification shown in Figure S, the main sewer pipe 1 is provided with atubuiar plastics liner 21 the diameter of which is considerablyjess than that of the main sewer. In such an arrangement it is possibleforthe wall ofthe liner 21 to be at a con siderable spacing from the opening to the branch pipe 2. It will therefore be appreciated that with a locating device of the type shown in Figu re 3 fitted within the pipe 2, the metal de#tector 22 may have to rely upon averyweaksignal from the steel ring 16to determine the appropriate location for cutting a port in the liner 21.To al!eviate this difficulty, the locating device 15 which is fitted as shown in Figure 5 within the branch pipe2(inasimilarmannertothatdis- cussed with reference to Figure 2) includes a location source such asan annularsteel plate 16which is supported from the steel ring 16 so that itwill be loc ated in the vicinity ofthe wall ofthe pipe21 21 when the latter isfitted. The supportforth#e plate 1-6a is con veniently provided by springs 30 which p-ermitthe plate 16a to be deflected should it prove necessary during fitting of the liner 21 and to subsequently re turn into alignment with the branch pipe 2.The metal detector 22 can now be used to determine the posi tion ofthe portwhich isto be cut bythe water jet cutter 25 by sensing from the plate 16a.

In-the embodiment of Figure 2, the carrier 7 with its laterally displaceable scissors linkage 10 is utilised for providing the service of positioning the locating device 15 within the branch pipe 2. However, the late rally displaceable part ofthe carrier can be modified to provide different services, for example to carry a detector or, as shown in Figure 6, for the platform 11 to carry a rotatable water jet cutting nozzle 31. By appropriate manoeuvring of the platform 11 as pre viously discussed, the nozzle 31 may be inserted into the branch pipe 2 and rotated to cutthrough-thewall ofthe pipe 2 circumferentially as indicated at 32.If a generally circular cut 33 is now made through the wall of the main sewer pipe 1 concentric with the branch pipe 2 (for example by use of a rotating cutter such as that shown at 25) it will be apparentthata short pipe section ofthe branch pipe 2 having a saddle-shaped external flange from the pipe 1 (and as indicated by the broken line 34) may fall into the bore of the pipe 1. Consequently the branch pipe 2 can be isolated from the main sewer pipe 1 so that, for example, if the main sewer pipe 1 is subsequently destroyed with a view to providing a new plastics main sewer, the integrity of the branch pipe 2 will be maintained for#subsequent connection to the new main pipe.It will be apparent that to achieve this lat ter connection and form an appropriate port in the new main pipe (which may then be regarded asa plastics liner extending through a bore in the ground), the procedure discussed with reference to Figure 2 can be followed to position a locating device within the branch pipe 2.

The locating means is not necessarily in the form of an annular or tubular device such as that shown at 15 in Figure 3 and may,forexample, be in the form of an inflatable bag carrying an appropriate material which is to be sensed bythedetecting means. However, the use of a tubular locating device is preferred since it will be apparentfrom Figure 2 that when the device 15 is fitted and isolated within the branch pipe 2, fluid flow communication is maintained from the branch pipe to the main pipe 1. The locating devices 15-can therefore be fitted in their respectiv#e branch pipes a long time before the plastics liner 21 is fitted without any disruption in the normal use of the branch pipes 2.

The possibility is envisaged of having the locating device (such as an inflatable chamber thereof) formed of or comprising a material which will rapidly degrade or disintegrate when subjected to the fluid which is to flow through the branch pipe; in this way the restriction formed by the locating means may soon be alleviated as the aforementioned material - breaks down when normal use of the branch pipe for fluid flow resumes and the debris of the locating means is flushed away.

Claims

1. A method of lining a main fluid conduit having a branch conduit which comprises positioning within the branch conduit a locating means having an extendible part, extending said extendible partto retain said locating means in engagement with the branch conduit; providing within the main fluid con duitatubularliner; insertingwithinthetubularliner detecting means which is responsive to said locating means and manoeuvring said detecting means to lo cate said locating means and from said location cutting through the linerwall from within the linerto form a port which substantially coincides with the branch conduit.

2. A method as claimed in claim 1 which com prises positioning the locating means within the branch conduit by insertion-therein from a position within the main fluid conduit.

3. A method as claimed in either claim 1 or claim 2 which comprises extending the extendible part by meansfromwithinthe main fluid conduit.

4. A method as claimed in any one of the preced ing claims in which the extendible part comprises an expandible chamber and the method comprises admitting fluid under pressure into the chamberto expand said chamber and retain the locating means in the branch conduit.

5. As method as claimed in claim 4which comprises admitting fluid from a hose and byway of a non-return valve on the locating means into the ex pandible chamber and detaching said hose from the locating means when the chamber is adequately expanded to retain the locating means in the branch conduit.

6. A method as claimed in claim 5 which com- prises automatically detaching the hose from the locating means bythe hose "blowing-off" when the fluid pressure in the expandible chamber attains a predetermined value adequate to retain the locating means in the branch conduit.

7. A method as claimed in any one of the preceding in which the locating means has at least one fluid passage extending therethrough and which comprises positioning the locating means within the branch conduit with said fluid passage maintaining fluid flow communication between the branch conduitandthe main fluid conduit.

8. A method as claimed in any one ofthe preceding claims in which the locating means has a metallic part and which comprises locating the locating means by detecting means which is responsive to said metallic part.

9. A method as claimed in claim 8 in which the metallic part is magnetic;

10. A method as claimed in any one ofthe preceding claims in which the extendible part comprises the or an expandible chamber which is expanded by fluid under pressure to retain the locating means in the branch conduit and which comprises removing the locating means from the branch conduitfollow ingtheformation of the port in the linerwall by bursting the expandible chamber to reduce the overall size ofthe locating means and moving the locating means into the bore of the linerthrough said port.

11. A method as claimed in claim l0which com- prises cutting the liner wall with a cutter and utilising such a cutterto burst the expandible chamber.

12. A method as claimed in any one of the pre- ceding claims which comprises manoeuvring the locating means longitudinallywith#in the main fluid conduit and rotationally about a longitudinally axis within said conduit to align the locating means with the branch conduit, and displacing the locating means laterally to position it within the branch conduit

13.A method as claimed in any one of the pre- ceding claims in which the main fluid conduit has several branch conduits and which comprises positioning and retaining in isolation a locating means one within each branch conduit; providing the main fluid conduit with a tubular liner; manoeuvring the detecting means to locate the respective locating means from within the liner and forming ports in the liner to coincide, substantially, with the respective branch conduit 3.

14. A carrierfor displacement longitudinally along a fluid conduit and which carrier comprises a body part; a portion on said body part mounted for rotation relative thereto about a longitudinal axis; drive means forcontrolling rotation of said portion; laterally extendible displacement means mounted on said portion of the carrierforcarrying service means, and means for controlling lateral displacement ofthe displacement means so that, by controlled longitudinal displacement of the carrier, rotation of said portion and lateral displacement of the displacement means, such service means as may be carried by the displacement means can be maneouvred to a desired position relative to said fluid conduit.

15. A carrier as claimed in claim 14 and having service means which is detachably carried on the displacement means whereby said service means can be maneouvred bythe carrier within the fluid conduit, located in a branch conduit ofthat fluid conduit and detached from the carrier to be retained inthe branch conduit.

16. Acarrierasclaimed in claim 15 in which the service means has a fluid flow passage therethrough whereby when the service means is located and retained in a branch conduit, fluid flow communication is maintained through said passage between the branch conduit and the fluid conduit.

17. Acarrierasclaimedineitherclaim 15or-claim 16 in which the service means has an extendible part and means is provided for extending that part so that, when the service means is located in the branch conduit, the extension of the extendible part retains the service means in the branch conduit.

18. A carrier as claimed in claim 17 in which the extendible part comprises an expandible chamber and means is provided for admitting fluid under pressure into that chamberto extend the service means.

19. A carrier as claimed in claim 18 and comprising a non-return valve on the service means through which fluid under pressure is admitted from a hose into the expandible chamber, said hose being mov able along the fluid conduit with the carrier and being detachable from the service meansfollowing expansion of the expandible chamberto isolate the extended service means.

20. A carrier as claimed in claim 19 in which the hose is automatically detachable from the service means by said hose "blowing-off" at a predetermined pressure within the expandible chamber.

21. A carrier as claimed in any one of claims 18to 20 in which the expandible chamber is elastomeric.

22. A carrier as claimed in any one of claims 18to 21 in which the expandible chamberis substantially toroidal.

23. A carrier as claimed in any one of claims 17 to 22 in which the service means is a locating means which comprises a source part to which a detecting means is responsive for locating said locating means through thewall of a tubularlinerofthefluid conduit.

24. A carrier as claimed in claim 23 in which said source part of the locating means is metallic for location magnetically or by a metal detectorthrough the wall ofthe liner.

25. Acarrieras claimed in either claim 23 or claim 24when appendentto claim 22 in which the locating means comprises the toroidal expandible chamber seated on a metallic ring which ring is capable of detection bythedetecting means.

26. A carrier as claimed in any one of claims 23 to 25 in which the source part is carried by support means of the locating means at a position remote from the extendible partwhereby,whentheexten- dible part is retained in a branch conduit, the support means locates the source part in the fluid conduit.

27. A carrier as claimed in claim 26 in which the support means comprises spring means which is temporarily deflectable in the fluid conduit.

28. A carrier as claimed in claim 14 and having service means comprising a cutter which can be manoeuvered by the carrier within thefluid conduit so that the cutter can belocated-in a branch conduit ofthatfluid conduitforthe purpose of cutting the wall of the branch conduit.

29. A carrier as claimed in any one of the claims 14to 28 in which the displacement means comprises a laterally extensible scissor-.type linkage, a fluid pressure operated ram or a lever and gear system.

30. A carrier as claimed in any one of claims 14to 29 in which the drive means for controlling rotation of said portion and the means for controlling lateral displacementofthe displacement means comprise electric motors.

31. Apparatus for use in the method of claim 1 which comprises a carrier displacable longitudinally within the main fluid conduit and carrying the locating means; displacement means for displacing the locating means laterally relative to the carrierto position the locating means with the branch conduit, and means for extending the extendible part of the locating means for retaining the locating means in engage mentwifh the branch conduit.

32. A main fluid conduit when lined bythe method as claimed in any one of claims 1 to 13.

33. A ca rrier as claimed in claim 14 and substantially as herein described with reference to the accompanying illustrative drawings.

34. A method of lining a main fluid conduitsubstantiallyas herein described.

35. A main fluid conduit when lined bythe method as claimed in claim 34.