Underground pipes such as water mains are sometimes in need of repair, owing to leakage. This can be environmentally damaging, depending on the fluid carried in the pipe, and costly as it is wasteful of that fluid. This is particularly so in the case of water. It is costly and time-consuming to excavate and replace an existing underground pipe with a new one, so the practice has arisen of lining such pipes with a plastic liner. This then has the disadvantage that for a branch, service connection, or"ferrule", say from a main into a dwelling, the liner can block off the ferrule against passage for say water from the main along the service connection to the dwelling, which would then be starved of supply. Methods and systems have therefore been developed for perforating the liner at the entrance to the ferrule. The problem then arises that there is an annular area at the ferrule entrance which allows water to flow between the liner and the main, so tending to reduce flow to the ferrule, lifting the liner from the main, and therefore flowing out of cracks to"leak", thus obviating the effectiveness of the liner and negating its function. It is an object of the invention to seek to mitigate this problem.

According to a second aspect of the invention there is provided a device for securing a liner of a host pipe adjacent a branch thereof, comprising a body which is adapted for self-support and for securing a liner adjacent the branch. The body may have a first part for insertion in the branch and for gripping a boundary wall thereof whereby to provide said self support and second part for engaging the liner. This provides a particularly simple yet effective construction.

The first part may have means on a surface thereof for gripping the boundary wall of the branch. This seeks to avoid unwanted withdrawal.

The means may comprise serrations, a particularly effective construction.

The first part may be sinuous. This provides for an effective construction having a relatively large area of contact of the device with a bore of the branch.

The first part may be of substantially U-shape, or may comprise two spaced elongate members, which may be substantially parallel.

The first part may also comprise a blade.

The blade may comprise a cruciform configuration. This again provides for an increased contact area.

The first part may also comprise a cylinder.

The body may comprise a resilient body. This provides for retention of the device in the branch, under tension.

The resilient body may comprise a second part adapted for engaging a liner exteriorly of an entry to the branch whereby to secure the liner adjacent that entry. This secures the liner against lifting and therefore seeks to prevent seepage behind the liner.

The second part of the body may comprise bearing means for bearing against the liner, which bearing means may comprise a ring shaped part.

The second part may also comprise a coil-shaped part.

The second part may comprise an annular shaped part, which may be dished.

The device may include adhesive securing means in the dish-shaped part, which adhesive securing means may comprise a butyl adhesive or an adhesive tape. This provides for added securing of the liner adjacent the branch.

According to a second aspect of the invention there is provided a method of securing a liner of a host pipe adjacent a branch thereof, comprising providing a host pipe with a branch, providing a liner in the host pipe, providing a device for securing the liner in the host pipe adjacent the branch, and mounting the device against the liner and on a surface facing into the host pipe whereby to secure the liner at the branch.

The liner may have a through orifice aligned with an entry to the branch, and the device may form the through orifice in the liner.

Restraining devices embodying the invention are hereinafter described, by way of example, with reference to the accompanying drawings.

Fig. 1 is an elevational view of a first embodiment of device according to the invention; Fig. 2 is an elevational view of a second embodiment; Fig. 3 is an elevational view of a fourth embodiment; Fig. 3A is a view on line A-A of Fig. 3; Fig. 4 shows a view of the embodiment of Fig. 2 in use; Figs. 5 and 5A are respectively side elevational and plan views of a fourth embodiment; Figs. 6 and 6A are respective perspective and plan views of a fifth embodiment; Figs. 7 and 7A show respective elevational and plan views of a sixth embodiment; Fig. 8 is an elevational view of part of a seventh embodiment; Fig. 9 is an elevational view of an eighth embodiment; Figs. 10 and 10A show respectively a perspective view of a ninth embodiment and a section of a main or host pipe with a branch or ferrule and the device of Fig. 10 in place; Figs. 11,11 A and 11B show steps in the installation of a tenth embodiment; Fig. 12 shows schematically a plan view of a pipe, ferrule and liner; Fig. 13 shows a liner of Fig. 12 after cutting; Fig. 14 shows a further embodiment of restraining or securing device according to the invention, for cutting the liner as shown in Fig. 13; and Fig. 15 and 16 shows respectively a plan view of the cut liner of Fig.

13 and a plan view when a further embodiment of cutter is used.

Referring to the drawings in which like parts are referred to by like numerals, there are shown devices 1-10 for securing a liner 11 (Fig.

4,1 OA, 11-11 B) of a host pipe 12 adjacent a branch, or ferrule 13 thereof, comprising a body which is adapted for self-support and for securing a liner 11 adjacent the branch or ferrule 13.

In Fig. 1, the device 1 shown has a one piece or integral body 14 of generally'T'configuration, a first part or"leg"15 of the'T'being sinuous and having securing means in the form of serrations 16 on external surfaces for contacting and hence gripping a boundary wall of a bore 17 of the ferrule 13, thereby enhancing retention. The bar, or second part 18, has upturned, as shown, ends 19 which are flat and which bear on the liner 11 at an edge thereof surrounding a hole 19 therein aligned with the ferrule bore, as shown in Fig. 4 which shows the device 2 of Fig. 2, which is essentially a modification of that of Fig. 1 in that the ends of the bar 18 support a backing or bearing ring 21 which bears on the liner edge which defines the hole in the liner to provide a greater bearing surface area which therefore has a more positive securing action on the liner edge.

Figs. 3 and 3A show a third embodiment 3 having a U-shaped first part with a bar 18 and backing or support ring 21, the legs of the U- shape having external serrations 16.

Figs. 5 and 5A show a device 4 which is formed from a single strip or rod to provide to upstanding legs 22 with outside serrations 16, a liner coil 23 or second part bearing on the liner in use.

Figs. 6 and 6A show an embodiment 6 having a curved or bent blade 24 forming a distal end of the first part and having teeth or serrations 16 for gripping the wall of the bore 17 of the ferrule, the blade flexing out of the plane of the paper on insertion in the bore to assist in retaining the device resiliently in place, under tension. The blade is on the end of a shaft 25, part of which is shown in Figs. 6 and 7.

Figs. 7 and 7A, 8 and 9 show parts of the embodiments 6,7,8 which have a pointed, arrowhead or dart end all of cruciform shape and which could be used to penetrate a thin-walled liner to produce the hole aligned with the bore of the ferrule. The shaft 25 or body part will terminate in a bar or other shape (not shown) forming a second part for holding the liner in position as for example shown in Fig. 4.

All the devices are resilient, being made from say sprung steel or plastic, as is the embodiment of Figs. 10 and 10A, which show a device 9 having a part 26 of any shape for surrounding the hole 19 in the liner 11 and the bore 17 of the ferrule 13 and a resilient curved part 27 for mounting the device 9 under tension.

Thus embodiment 9 is particularly suitable where the bore of the ferrule is small, in which case devices which are inserted in the bore may, unlike embodiment 9, be unacceptable as they could impose unacceptable restriction on water flow into and along the ferrule from the main or host pipe.

Figs. 11A and 11 B show a tenth embodiment 10 of a device which has a cylindrical first part 28 and an annular, dished or concave second part 29 which can contain additional means 30 in the form of an adhesive means for securing and sealing the edge of the liner 11 adjacent the hole 19.

The adhesive means 30 may be butyl adhesive or an adhesive tape such as PTFE tape.

Figs. 1 1 A and 11 B show two steps in mounting of the device, the step of piercing the liner being shown in Fig. 11, the hole or opening being formed either by a"hot finger" (not shown) or being a fluted or cruciform shape like that of Figs. 6 to 9 which on insertion provides a petalled strip of material of the liner. This operation could be carried out with the pipe flooded, which may be advantageous where the liner is a thin-walled liner which might not hold its tubular shape. The pressure of the water would maintain this shape.

In all embodiments, the size of the first part, when it is inserted in the bore, is such as to be a resilient push fit in that bore so retaining the device self-supportedly in position under tension. All the devices are of such dimension that passage of water through the ferrule is not unduly hindered. The devices 1-10 are forced into position after the thin-wall liner has been pierced, possibly by blade 24, or a circular coupon of liner has been cut out by say a robot, and removed. Thus, where a ferrule 13 protrudes interiorly of the host pipe 12, that is it protrudes beyond the inner surface thereof into the interior, generally in a radial direction, this can in certain circumstances cause the liner 11 to pull the butyl adhesive 30 away from a recess 31 at the base of the ferrule 13 so preventing the butyl 30 from bonding to the host pipe 12 adjacent the protruding ferrule 13 as shown in Fig. 12. there is a"dead area"at'X','X', and at this area a cutter is applied to cut the liner 11 as shown in Fig. 13. In a preferred embodiment, the cutter is a raised cutting element or knife 32 on the circular part 26 of a modified embodiment 9'of device 9 of Fig. 10, which embodiment is shown in Fig. 14. Thus in use, the"coupon"or disc 11'of liner 11 is removed in the direction of arrow'Y'to open up the base of the ferrule 13 into the bore of the host pipe 12, and when the restraining device 9'of Fig. 14 is applied and cuts the liner 11 at 'X'-'X', the butyl adhesive adheres at 31 to the host pipe 12 and exterior surface of the ferrule 13 as shown in Fig. 13, so that the liner is held firmly in place, the cut edges of the liner 11 being sealed by the butyl adhesive 30. This is particularly so when the liner is inserted in a flooded pipe as the pressure of the water will ensure that the liner is forced against the pipe, and ferrule, as shown. If the cutting element or blade is circular, a plan view of the cut liner 11 and ferrule 13 would be as shown in Fig. 15. Fig. 16 shows a modification which is essentially like a gear or star 32 in plan, where the cutting element or blade has a"pastry cutter"kind of gear or star configuration in plan, this arrangement also allowing for secure attachment of the liner 11 round a protruding ferrule 13.

Thus, all the securing or restraining devices illustrated are self- supporting in use and for securing a liner adjacent a branch, or ferrule.