GB2263751A

GB2263751A - Pipe blocking method and apparatus therefor

Info

Publication number: GB2263751A
Application number: GB9306528A
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: GB2263748A; GB2263749B; GB2263748B; GB2263749A; GB2263747A; GB2263696B; GB2263696A; GB2263750B; GB9306524D0; GB9306528D0; GB2263744B; GB2263751B; GB2263747B; GB9306522D0; GB9306527D0; GB9306523D0; GB9306526D0; GB2263743A; GB9306525D0; GB2263744A

Abstract

A method of blocking a pipe (10) extending between a main (12) and a tap (20) comprising: fitting a gland (50 or 80) (Figs 4, 5) to the downstream side of the tap; introducing a block (170) through the gland, the tap and the pipe and into the main, by means of a flexible rod removably attached to the downstream end of the block; retracting the block to seal it against the internal wall of the pipe immediately downstream of the junction of the pipe with the main; disengaging the flexible rod from the block and withdrawing it through the tap and the gland. The gland is then removed. <IMAGE>

Description

PIPE BLOCKING METHOD AND APPARATUS THEREFOR The invention relates to an improved method and apparatus for blocking a pipe. It finds particular application in the blocking of domestic gas service pipes. 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.

It is often necessary to cut off a mains fed gas supply temporarily or permanently. Using current techniques, this is achieved by cutting a service pipe 10 close to its junction 22 with the main. This necessitates digging to uncover the junction, and closing off the main supply whilst the service pipe 10 is cut and the main capped. This is costly to do and undo.

The present invention provides a method and apparatus therefor which does not involve cutting the service pipe downstream of the main and capping it.

The present application is divided from U. K. Patent Application No. 9003723.5 According to the present invention there is provided a method of reversibly blocking a pipe extending between a main and a tap comprising: fitting a gland to the downstream side of the tap; introducing a block through the gland, the tap and the pipe into the main, by means of a flexible rod removably attached to the downstream end of the block ; retracting the block to seal it against the internal wall of the pipe immediately downstream of the junction

of the pipe with the main; disengaging the flexible rod from the block and withdrawing it through the tap and the gland; removing the gland.

If it is desired to remove the block, a method comprising the following steps is employed: a flexible rod adapted, for example by means of a hook at is leading end, to engage the block is introduced into the pipe through the gland and the tap, and engaged with the block, which is then pulled out through the tap and the gland; the tap is closed; the gland is removed from the tap.

Alternatively, if'it is contemplated that the supply will not be recoonnected to the pipe, the pipe may be filled with a sealant after the block has been placed in it.

The invention contemplates, in a second aspect, a kit comprising: a gland for sealing an open end of a pipe so as to allow the passage of equipment such as liner pipe, pipe seals and seal breaking tools into and out of the pipe, comprising a cylindrical housing one end of which is adapted to be affixed to the open end of a pipe, and at least one star seal within the housing; and a pipe block comprising: a spine having an upstream end and a downstream end; a resilient anchor toward the upstream end of the spine comprising at least two resilient arms extending outwardly from the spine; at least one resilient annular flange extending from the spine downstream of the anchor, the anchor and the or each flange being associated with an annular shoulder adjacent and immediately upstream of the anchor or the flange; and means provided on the block to demountably receive a rod.

Preferably, the housing of the gland is in two parts which fit tightly together, for example by screw threads.

In the first preferred embodiment of the second aspect of the invention, the four star seals are arranged in pairs, the two pairs being separated from each other by a spacer having a cylindrical central passage.

In a preferred embodiment, the kit further comprises: a sealant head comprising: a cap, the open end of which is adapted, for example by provision of a screw thread, to be sealingly engaged by a free end of the pipe to be sealed ; and an opening for the introduction of sealant, preferably provided with a one-way valve to prevent sealant leaving the capped pipe.

Preferably, the opening of the sealant head is in the cap wall opposite the open end and has a removable closure.

The gland, pipe block and sealant head are the subject of

copending U. K. Patent Applications Nos.,,, , and, respectively, which, like the present application, are divided from U. K. Patent Application No. 9003723. 5.

The various aspects of 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 2a shows a side elevation of a preferred pipe block for reversibly blocking a pipe in a method according to the invention; Figure 2b shows a downstream (front) and elevation of the block of Figure 2a;

Figure 3 shows a longitudinal cross-section through the block of Figures 2a and 2b in position blocking a pipe; Figure 4a shows a cross-section through a gland for use in a method according to the invention; Figure 4b shows a plan view of a seal of the gland of Figure

4a ; Figure 5 shows a cross-section through a gland for use in a method according to the invention; Figure 6 shows a preferred sealant head for use in a method of permanently blocking a service pipe according to the invention; Figure 7 shows a sealant head for introducing sealant into a pipe closed by the block of Figure 2.

The pipe block 170 used in methods according to the invention, shown in Figures 2a, 2b, and 3 comprises a central threaded shaft 172 (the threads of which are not shown in Figure 3). A first annular shoulder 174 of steel is mounted on the shaft 172 toward its upstream end. An anchor 176 is mounted on the shaft adjacent to and downstream of the first shoulder. The first shoulder and the anchor are held in place by nuts 178a, b on the shaft.

The anchor 176 is a generally cruciform rubber flange. The four arms 180a, b, c, d of the anchor extend beyond the rim of the first shoulder 174 and are swept back slightly to facilitate insertion of the blockage 170 in a pipe.

On the shaft 172 downstream of the anchor 176 is a second annular steel shoulder 182, the upstream face of which abuts a nut 184 on the shaft 172. On the shaft 172 immediately downstream of

the second shoulder 182 is a first annular rubber sealing flange 186 of greater diameter than the second shoulder 182.

A rubber sleeve 188 carrying two spaced apart rubber sealing flanges 190a, b fits over the downstream end of the shaft 172. The downstream end of the sleeve 188 is closed apart from a small central passage 192. The sleeve also carries at its downstream end a metal flange 194, from which extends, in the downstream direction, metal legs 196 supporting a metal ring 198, concentric with the shaft 172 and the sleeve 188.

An insertion rod 200 is attached to the end of the rubber sleeve 188 by a narrow, weakened, end portion 202, which passes through the central passage 192 in the end wall of the sleeve 188 and ends in a disc 204 (see Figure 3), too large to pass through the central hole 192.

Methods of the invention use a gland which together with a pipe block provides a kit according to one aspect of the invention.

Preferred glands are described below.

The first embodiment 50 of a gland in Figure 4a 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 4b. 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 5 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.

In preferred methods of the invention, a sealant head is employed to introduce sealant into the service pipe. Preferred sealant heads are described below.

The first sealant head 140 of Figure 6, which is shown screwed onto the open end of a gas service pipe 10 lined with a liner pipe 112, comprises a cylindrical body 142 surmounted by a narrower neck section 144. The bottom end 146 of the head 140 is open and threaded on its internal surface, to screw onto the service pipe 10.

The liner pipe 112 extends through the body 142, and the neck 144 is sealed around the liner pipe 112 by an olive 148 around the liner pipe which rests on a flange 150 inside the neck 144. The olive 148 seals against the inside surface of the neck 144 by means of a cap 152 with a central passage, for the liner pipe 112, which screws into the neck 144 of the head 140 and presses onto the olive 148. An externally threaded collar 154 extends around the top of the cap 152 for attachment to a tap.

A hollow side arm 156 for the introduction of sealant extends up and away from the lower end portion of the body 142 of the head 140, and communicates therewith. The free end of the arm 156 is internally threaded to receive either a sealant hose or a plug. The side arm 156 may be provided with a one-way valve, such as a spring loaded ball valve, or a top-hat valve, to prevent sealant from spilling out of the arm when the sealant hose is disconnected from it after use. The body 142 is vented by vent 158.

The second sealant head 220 of Figure 7, which is shown screwed onto the open end of gas service pipe 10 which is blocked by a pipe block (not shown), comprises a cap 222 which has an internally threaded open end 224 for engagement with external threads on the gas service pipe 10. Opposite the open end a hollow arm 226 opens from the cap. A one-way top-hat valve 228 is provided in the arm.

Two retaining rings 234 around the valve 228 located in grooves 236 around the internal wall of the hollow arm 226 to retain the valve.

The free end 230 of the arm is externally threaded.

In use, the block 170 is introduced into the service pipe 10 to be sealed through a gland and through the tap 20 on the pipe. It is pushed by the rod 200 along the service pipe 10 until it passes into the main 112. If the blockage 170 has been introduced through the gland 50 of Figure 4a, a water gauge connected to the water gauge connector 68 of the gland 50 will register this event.

The block 170 is then pulled back into the service pipe 10 with the rod 200, so that it jams in the opening of the service pipe 10, as can be seen from Figure 3. The arms 180a, b, c, d of the anchor 176 are bent upstream over the first shoulder 174 to jam against the internal wall of the pipe 10 to hold the block 170 in place. The sealing flange 186 on the shaft 172 is also bent upstream over the second shoulder 182 and seals against the internal wall of the pipe 10 to provide a gas tight seal. The two flanges 190a, b on the sleeve 188 are also bent upstream to seal against the internal wall of the pipe 10.

Further tension on the insertion rod 200 causes the weak end portion 202 of the rod to break, and the rod is withdrawn from the pipe. The disc 204 which held the rod in the sleeve 188 remains in the sleeve (see Figure 3). The gland is then removed.

If it is desired to remove the block 170 from the pipe, a removal rod carrying at its end a hook is inserted, through a gland and the tap into the pipe. The hook engages with the ring 198 at the downstream end of the block 170, and the block is removed from the pipe 10 through the tap and the gland by pulling on the removal rod. The tap is closed and the gland removed.

If the block is to remain permanently in the pipe, sealant can be poured into the pipe, for example through the sealant heads 140,220 of Figures 6 and 7. A preferred sealant composition for use in the method of the invention comprises: a cementitious material, such as portland cement;

a plastics binder, such as polyvinylacetate; and water.

The preferred proportions by volume of cementitious material: binder: water are 1.2 : 1: 1.

In the case of the second sealant head 220, the open end 224 of the cap 222 is screwed tightly onto the open end of the blocked service pipe 10. The closure 232 is unscrewed from the free end 230 of the hollow arm 226, and replaced by the nozzle of a sealant pump.

Sealant is pumped in through the valve 228 to fill the service pipe 10 between the block and the cap. The sealant pump is removed, and the closure 232 replaced.

The method of the invention provides a quick, cheap safe and convenient way of blocking a pipe permanently or long-term temporarily.

Claims

CLAIMS 1. A method blocking a pipe extending between a main and a tap comprising: fitting a gland to the downstream side of the tap; introducing a block through the gland, the tap and the pipe and into the main, by means of a flexible rod removably attached to the downstream end of the block; retracting the block to seal it against the internal wall of the pipe immediately downstream of the junction of the pipe with the main; disengaging the flexible rod from the block and withdrawing it through the tap and the gland; removing the gland.
2. A method of temporarily blocking a pipe comprising blocking it by a method according to claim 1 by introducing a flexible rod adapted to engage the block into the pipe through the gland and the tap, engaging the rod with the block, and pulling the block out through the tap and gland, thereby unblocking the pipe; closing the tap; removing the gland from the tap.
3. A method of permanently blocking a pipe comprising blocking it by a method according to claim 1 comprising filling it with a sealant after the block has been placed in it.
4. A kit comprising: a gland for sealing an open end of a pipe so as to allow the passage of equipment such as liner pipe, pipe seals and seal breaking tools into and out of the pipe, comprising a cylindrical housing one end of which is adapted to be affixed to the open end of a pipe, and at least one star seal within the housing; and a pipe block comprising: a spine having an upstream end and a downstream end;

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a resilient anchor toward the upstream end of the spine comprising at least two resilient arms extending outwardly from the spine ; at least one resilient annular flange extending from the spine downstream of the anchor, the anchor and the or each flange being associated with an annular shoulder adjacent and immediately upstream of the anchor or the flange; and means provided on the block to demountably receive a rod.
5. A kit according to claim 4, further comprising a sealant head comprising: a cap, the open end of which is adapted to be sealingly engaged by a free end of the pipe to be sealed; and an opening for the introduction of sealant.
6. A kit according to claim 5, in which the open end of the cap of the sealant head is adapted by provision of a screw thread.
7. A kit according to claim 5 or 6, in which the opening of the sealant head has a one-way valve to prevent sealant leaving the capped pipe.
8. A kit according to any of claims 5 to 7, in which the opening of the sealant head is in the cap wall opposite the open end.
9. A kit according to any of claims 5 to 8, in which the opening of the sealant head has a removable closure.
10. A kit according to any of claims 4 to 9, in which the gland comprises two star seals.
11. A kit according to any of claims 4 to 10, in which the gland comprises four star seals.

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12. A kit according to claim 11, in which the four star seals are arranged in pairs, the two pairs being separated from each other by a spacer having a cylindrical central passage.
13. A kit according to any of claims 4 to 12, in which the resilient anchor comprises four resilient arms extending outwardly from the spine of the anchor.
14. A kit according to any of claims 4 to 13, in which the housing of the gland is in two parts.
15. A kit according to claim 14, in which the two parts of the housing are threadedly connected together.
16. A method of blocking a pipe, substantially as herein described.
17. A kit substantially as herein described with reference to Figures 2a, 2b, 3,4a and 4b or 2a, 2b, 3 and 5 of the accompanying drawings.
18. A kit substantially has herein described with reference to Figures 2a, 2b, 3,4a, 4b and 6 or 2a, 2b, 3,5 and 6 of the accompanying drawings.