GB2263747A

GB2263747A - Pipe block

Info

Publication number: GB2263747A
Application number: GB9306522A
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: GB2263750A; GB2263696A; GB2263747B; GB2263743B; GB9306522D0; GB2263743A; GB9306529D0; GB2263751A; GB9306526D0; GB2263749A; GB2263744B; GB2263751B; GB9306527D0; GB9306525D0; GB2263696B; GB9306528D0; GB2263750B; GB9306524D0; GB9306523D0; GB2263749B

Abstract

A pipe block (170) comprises a spine (172) having an upstream end and a downstream end; a resilient anchor (176) toward the upstream end of the spine (172) comprising four resilient arms (180a, b, c, d) extending outwardly from the spine (172); at least one resilient annular flange (190a) extending from the spine (172) downstream of the anchor (176), the anchor being associated with an annular shoulder (174) adjacent and immediately upstream of the anchor or the flange; and means (188, 202) provided on the block (170) to demountably receive a rod (200). Three annular flanges (186, 190a, 190b) are provided. A metal flange (194) carries a metal ring (198) on metal legs (196). <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 blocking a pipe such as a domestic gas service pipe.

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. A technique which does not involve cutting the service pipe downstream of the main and capping it is described in copending U. K. Patent Application No.

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

According to the invention there is provided 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 and preferably four 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.

In use, the block is introduced through a gland on the tap into a service pipe to be blocked and pushed down the pipe by a rod attached to the blockage. When the blockage has entered the main, it is pulled back into the pipe, whereupon the resilient arms of the anchor jam against the internal wall of the service pipe and are prevented by the shoulder from being pulled into the pipe. The or each sealing flange is urged over its associated shoulder to seal against the internal wall of the pipe. The rod is then detached and withdrawn from the pipe.

To remove the block, a rod is introduced into the pipe, through a gland, and connected to the block, which is then pulled out with sufficient force to overcome the sealing and anchoring.

The gland is the subject of copending U. K. Patent Application No. which, like the present application, is divided from U. K. Patent Application No. 9003723.5.

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 the preferred pipe block 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 of blocking a pipe; Figure 4b shows a plan view of a seal of the gland of Figure 4a; Figure 5 shows a first preferred sealant head for use in a method of relining a service pipe; Figure 6 shows a second preferred sealant head for introducing sealant into a pipe closed by the block of Figures 2a, 2b and 3.

The pipe block 170 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 11), too large to pass through the central hole 192.

The block of the invention finds particular application in a method of blocking a pipe which employs a gland of the type described below.

The gland 50 shown 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.

A sealant head of the types described below may be advantageously employed with a pipe block according to the invention in a method of blocking a pipe.

The first sealant head 140 of Figure 5, 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 155 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 6, 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 5 and 6. A preferred sealant composition 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 of Figure 6, 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 block according to the invention, and method and sealant head described with reference to Figures 2a, 2b, 3 and 6, provide a quick, cheap safe and convenient way of blocking a pipe permanently or long-term temporarily.

Claims

CLAIMS 1. 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.
2. A pipe block according to claim 1, in which the resilient anchor comprises four resilient arms extending outwardly from the spine.
3. A pipe block substantially as herein described with reference to Figures 2a, 2b and 3 of the accompanying drawings.