GB2263748A

GB2263748A - Pipe block

Info

Publication number: GB2263748A
Application number: GB9306523A
Authority: GB
Inventors: Michael John Hicks
Original assignee: British Gas PLC
Current assignee: British Gas PLC
Priority date: 1989-09-22
Filing date: 1993-03-29
Publication date: 1993-08-04
Anticipated expiration: 2010-02-19
Also published as: GB9306527D0; GB2263749A; GB9306526D0; GB2263743A; GB2263744B; GB2263743B; GB9306523D0; GB2263750A; GB2263750B; GB9306524D0; GB9306522D0; GB9306525D0; GB2263749B; GB2263751B; GB2263751A; GB9306528D0; GB9306529D0; GB2263696A; GB2263748B; GB2263747A

Abstract

A plug (30) for sealing a pipe comprises a spine (38), three sealing flanges (34a, b, c,) of resilient material integral with the spine and extending perpendicular to the principal axis of the spine, which seal against the internal wall of the pipe, and an elongate handle (40) detachably mounted on the spine for introducing the plug (30) into the pipe. <IMAGE>

Description

PIPE BLOCK The invention relates to a block for a pipe, to stop the flow of fluid through the pipe. It finds particular application in a method and apparatus for relining a pipe, such as a domestic gas service pipe, with a new pipe, such as a polyethylene pipe. Such method and apparatus is the subject of U. K. Patent Application No.

9003723.5 from which this application has been divided.

It is often necessary to replace original pipe with new pipe, because of corrosion and other deterioration of the original pipe.

In cases in which the original pipe is buried, removal and replacement is expensive, time consuming and inconvenient, since it necessitates digging up the entire length of original pipe, and interruption of the supply.

To reduce the cost and inconvenience of pipe replacement, techniques have been developed to reline existing pipe in situ. A liner pipe, such as a flexible polyethylene pipe, is inserted into a free end of the original pipe, and fed, if necessary with the aid of a pipe jack, along the original pipe.

In many cases, such as that of a domestic gas supply, this operation, although simpler than pipe replacement, is still complex, since it involves digging, cutting the pipe to be relined to isolate it from the main supply and capping of the cut end.

A typical gas supply is shown in Figure 1. A service pipe 10 is connected at one end to a buried gas main 12, passes through the ground 14, and the wall 16 and the floor 18, of the house and is connected to a tap 20. In Figure 1, the upstream side of the tap is shown unconnected. Normally, it will be connected to a domestic gas meter.

In order to reline the service pipe using current techniques, it must be cut close to its junction 22 with the main 12. This necessitates digging to uncover the junction, and closing off the main supply whilst the service pipe 10 is cut and the main capped.

The tap 20 is then removed, the polyethylene liner pipe inserted into the service pipe and the tap reconnected. The main supply must again be closed off whilst the service pipe 10 is reconnected to the main 12. The operation is time consuming and inconvenient.

A technique for relining pipes, such as gas pipes, which does not involve digging-or cutting of pipes and which minimises the risk of leakage is described in U. K. Patent Application No. 9003723.5.

The plug of the present invention is particularly suited for use in this technique.

According to the invention, there is provided a plug for sealing a pipe comprising: a spine, at least one, preferably two and more preferably three sealing flanges of resilient material integral with the spine and extending generally perpendicular to the principal axis of the spine, which, in use, seal against the internal wall of the pipe; and an elongate handle coextensive with the spine for introducing the plug into the pipe. The handle may be detachably mounted on the spine.

Preferably, the plug can pass through a tap on the end of the pipe.

The invention will be further described, by way of example, with reference to the drawings, in which: Figure 1 shows a typical domestic gas supply;

Figure 2 shows a side elevation of a preferred plug according to the invention; Figure 3a shows a cross-section through a gland for use with the plug of Figure 2 in a method of relining a service pipe ; Figure 3b shows a plan view of a seal of the gland of Figure 3a; Figure 4 shows a cross-section through a gland through which the plug of Figure 2 is inserted in a method of relining a service pipe; The plug 30 of Figure 2 according to the invention is a single piece of rubber comprising a spine 32 having upstream 34a, middle 34b and downstream 34c circular flanges extending therefrom. The peripheral regions 36a, b, c of the flanges are bevelled, the upstream face of each flange being of smaller diameter than the downstream face.

Figure 2 shows the upstream end of the plug 30 attached, by means of cooperating screw threads, to a flexible rod 38 having at its free end a handle 40.

The flanges 34a, b, c are so dimensioned that they can be introduced into a service pipe 10 through a tap 20 (see Figure 1).

They firstly pass through a gland on the outlet of the tap, which is then opened to allow the plug 30 into the service pipe. The flanges 34a, b, c then seal against the inner wall of the service pipe, so that the tap can be removed.

The first embodiment 50 of a gland in Figure 3a comprises a circular cylindrical steel body 52 with internal threads 54 at its lower end for connection to the threaded end of a service pipe 10 (see Figure 1) and external threads 56 at its upper end. The body

52 has a wide portion 58 about a third of the way down, for reception of circular star seals 60a, b, c, d of rubber. A star seal 60 is shown in Figure 3b. It comprises a circular disc of rubber which has six radial slits 62 in it extending toward, but stopping short of, its edge. Normally, the edges of the slits 62 close to provide a gas tight seal. However, pipes and other equipment can be pushed through the seal 60, deflecting the sectors defined by the slits 62, which then return to the sealing condition.

The sectors will seal against a relatively narrow rod passing through the seal.

The star seals 60a, b, c, d are arranged in the wide portion 58 of the gland 50 in two pairs 60a, b and 60c, d. The pairs of seals are separated by a plastic spacer ring 64.

The gland 50 is provided, upstream of the seals 60a, b, c, d, with a pressure relief valve 66 and a water gauge connection 68, both of which communicate with the interior of the gland 50.

The second embodiment 80 of the gland shown in Figure 4 comprises a circular cylindrical body 82 having a rebated externally threaded neck 84 at its upper end and a wide internally threaded recess 86 at its lower end. An annular flange 88 runs around the inside wall of the body 82 about a third of the way down it.

A cap 90 having a central passage 92 screws onto the neck 84 of the body-82. A first star seal 94a is trapped between the inner face of the cap 90 and the upper face 96 of the body 82. A second star seal 94b rests on the flange 88 in the body 82. A spacer ring 98 maintains the separation of the star seals 94a, b. The two seals 94a, b and the spacer ring 98 may be provided as a single element.

A cylindrical adaptor 100 screws into the recess 86 at the lower end of the body 82 of the gland 80. The inner wall of the adaptor 100 is threaded at its lower end 102 to receive a tap. By

employing an adaptor 100 having a suitable dimension at its lower end 102 the gland 80 can be affixed to taps of different diameters.

The body 82 of the gland 80 is provided below the seals 94a, b, with a water gauge connection 104, which communicates with the interior of the gland.

The gland 80 according to the second embodiment shown in Figure 4 is prepared as follows.

The rod 38 of the plug 30 (see Figure 2) is inserted into the body 82 of the gland 80 through the central passage 92 in the cap 90 of the gland and the two star seals 94a, b. The adaptor 100 of the gland 80 is unscrewed from the body. The rod 38 is screwed onto the downstream end of the plug 30, which is then pulled, by the rod, into the body 82 of the gland 80. The adaptor 100 is rejoined to the body 82.

The prepared gland 80 is screwed onto the free, downstream, side of the tap 20, which is thus sealed. The tap 20 is opened, and the plug 30 is pushed through the tap 20 and into the service pipe 10 by the rod 38. The flanges 34a, b, c on the spine 32 of the plug 30, which are of slightly greater diameter than the internal diameter of the service pipe 10, deform against the internal walls of the service pipe 10 to make a gas tight seal.

The rod 38 is unscrewed from the plug 30 and withdrawn through the tap 20 and the gland 80. A water gauge connected to the water gauge corrector 104 on the gland 80 confirms that the seal has been made. The tap 20, with the gland 80, is unscrewed from the end of the service pipe 10.

The gland 50 according to the first embodiment shown in Figure 3a is screwed onto the end of the service pipe 10. The

rod 38 of the plug 30 is inserted into the service pipe through the star seals 60a, b, c, d of the gland 50, and attached to the plug 30. The plug 30 is withdrawn from the service pipe 10 through the gland.

Claims

CLAIMS 1. A plug for sealing a pipe comprising: a spine, at least one sealing flange of resilient material integral with the spine and extending generally perpendicular to the principal axis of the spine, which, in use, seal against the internal wall of the pipe; and an elongate handle coextensive with the spine for introducing the plug into the pipe.
2. A plug according to claim 1, comprising two sealing flanges.
3. A plug according to claim 1 or 2, comprising three sealing flanges.
4. A plug according to any preceding claim, in which the elongate handle is detachably mounted on the spine.
5. A plug substantially, as herein described with reference to Figure 2 of the accompanying drawings.