GB2207728A

GB2207728A - Temporarily or permanently blocking the bore of a pipe

Info

Publication number: GB2207728A
Application number: GB08729183A
Authority: GB
Inventors: Peter Smith
Original assignee: British Gas PLC
Current assignee: British Gas PLC
Priority date: 1987-07-23
Filing date: 1987-12-15
Publication date: 1989-02-08
Anticipated expiration: 2007-12-15
Also published as: GB9104683D0; GB8729183D0; AU1924988A; AU628487B2; AU5127590A; GB2207728B; GB2239687B; GB8717404D0; AU1391292A; AU599501B2; AU636078B2; GB2239687A

Abstract

The bore of a gas service pipe is temporarily of permanently blocked by forcing a resilient ball 6 along the pipe 5 from the gas meter tap end of the pipe 5 by gas pressure, the ball 6 forming a force fit sufficient to resist any attempt to dislodge it by the pressure of gas in the pipe 5. The ball 6 is forced to a position where it is outside the gas consumer's premises 1. A releasable cable 7 may be attached to the ball 6. <IMAGE>

Description

TITLE: Temporary or Permanent Blocking of the Bore of a Pipe The present invention relates to the temporary or permanent blocking of the bore of a pipe through which fluid flows and is particularly directed to the temporary blocking of a service pipe carrying natural gas.

Should a gas supplying authority wish to cut of the supply of gas to a consumer for any reason (eg. the consumer has defaulted on payment of a bill), safety regulations require that the gas supply be eventually cut off at a point outside the consumer's property or premises.

One method of achieving this is to dig down outside the property or premises to the service pipe connection to the main and then to cut the service pipe and plug it with a set table sealing compound to cut off the supply.

In the case where the property comprises a block of flats the service pipe may be sealed by an expanding polyurethane foam.

The above method is inconvenient since it involves excavation to cut off the supply and it is therefore an object of the present invention to provide a method for cutting off a gas supply without this disadvantage.

According therefore to one aspect of the present invention we provide a method for temporarily or permanently blocking the bore of a pipe through which fluid flows, the method comprising gaining access to the bore of the pipe at a suitable point, inserting into the pipe at the point a compressible seal which is adapted to form within the bore of the pipe a force fit sufficient to resist any attempt to dislodge it by the pressure of the the fluid and forcing the seal along the pipe counter to the direction of fluid flow to a position along the length of pipe upstream of the suitable point.

According to another aspect of the present invention we provide apparatus for temporarily or permanently blocking the bore of a pipe through which fluid flows, the apparatus comprising a compressible seal for insertion into the pipe at a suitable point, the seal being adapted to form within the bore of the pipe a force fit sufficient to resist any attempt to dislodge it by the pressure of the fluid and means for forcing the seal along the pipe counter to the direction of fluid flow to a position within the pipe upstream of the suitable point.

According to yet another aspect of the present invention, we provide a resilient ball incorporating means permitting the ball to be releasably connected to a cable.

An embodiment of the invention will now be particularly described with reference to the drawings in which : Figure 1 is a schematic arrangement of a typical property connected to a natural gas supply, Figure 2 illustrates suitable equipment for effecting the method, and Figure 3 is a view partly in section of a suitable seal and associated cable and stop for limiting the distance travelled by the seal along the service pipe.

Referring to Figure 1, there is shown located within an outhouse or garage 1 adjacent to the dwelling 2 a gas meter 3 and gas meter tap 4 which latter enables the consumer to turn off the gas supply. The gas is supplied to the meter 3 by means of a service pipe 5 which is connected at its far end to a feeder main (not shown). To satisfy safety regulations, should it prove necessary for the gas supplying authority to cut off the consumer, the gas supply must be cut off at a point outside the outhouse 1 ie. at a point in the service pipe which lies below ground.

In the case of the present invention, this is generally effected in the following manner.

Firstly, the gas meter tap 4 is closed to shut off the gas supply to the meter 3. Next the gas meter tap 4 is disconnected from the meter 3 and then a compressible seal is inserted into the now open outlet end of the gas tap 4, the seal forming within the tap 4 and also within the bore of the service pipe 5 a force fit sufficient to resist attempts by the gas pressure to dislodge it. The gas meter tap 4 is then opened and the seal is forced along the service pipe 5 to a suitable point beyond the outhouse eg. to a point in the underground section of the service pipe 5.

As shown in Figure 3 the seal may be in the form of a ball 6 of a resilient compressible material eg. a resilient thermoplastic. The ball 6 may be forced along the service pipe 5 by pressurised gas eg.

natural gas. The ball 6.itself is held on a flexible steel tether or cable 7. The: latter has an externally threaded end 8 which is releasably screwed into an internally threaded bush 9 held captive within the ball 6. A movable stop 10 is threaded on the cable 7 to adjust the length of cable 7 following the ball 6 for the purpose to be described. The stop 10 can be releasably secured to the cable 7 by means of a thumb-screw 11 which engages the cable 7 as shown.

The ball 6 is moved by applied gas pressure pushing a grease lubricant ahead of it until the stop 10 engages with a predetermined limit means and the cable 7 becomes taught. The gas pressure behind the ball 6 is then released and the cable 7 unscrewed by twisting it to release its end 8 from the bush 9. The cable 7 can then be removed, the gas tap 3 closed and the service pipe 5 capped off, if necessary. The length of cable 7 between the ball 6 and the stop 10 can be adjusted to ensure that the ball 6 is outside the consumer's dwelling.

If it is intended permanently to block the bore of the pipe the ball may simply be left in position. In addition the pipe may be plugged with a suitable sealant at a point within the pipe between the ball and the pipe outlet.

If however, it is possible that the consumer may be reconnected at some time in the future the pipe is not plugged with sealant.

In order-to reconnect the consumer to the gas supply the ball 6 may be sucked out of the service pipe by means of a vacuum pump.

It may be necessary to spray the walls of the service pipe with lubricant to effect such removal.

The equipment shown in Figure 2 comprises a reception chamber 20 for the ball, having one end 21 for connection to the gas tap outlet 22 and an opposite end 23 comprising a gland (not shown) through which the cable 7 can be inserted, the gland in use forming a seal with the cable 7. Valves 24,25 on opposite sides of the chamber 20 provide means for connecting the chamber 20 to a source of compressed natural gas where the ball is to be forced up the pipe or to a vacuum pump where the ball is to be removed from the pipe. The opposite end 23 of the chamber 20 has a nut 26 serving as a limit for movement of the cable stop 10.

In use of the equipment to insert the ball 6 into the service pipe 5, the threaded end 8 of the cable 7 is inserted through the gland end of the chamber 20 and is then screwed into the threaded bush 9 of the ball 6. The ball 6 is then pulled by the cable 7 into the chamber 20. The chamber 20 is then connected to the gas tap outlet 22 (the tap at this stage being closed) and the valve 24 say is connected to a supply of compressed natural gas (the valves 24,25 being closed). The gas tap 4 is opened and then the valve 24 is opened causing the ball 6 to be forced along the service pipe 5 until the stop 10 engages with the nut 26. The stop 10 is then released from the cable 7 and is slid away from the nut 26 to enable the cable 7 to be released from the ball 6.

Any excess gas pressure in the pipe 5 is released by opening the other chamber valve 25. The gas tap 4 may then be closed and the chamber 20 removed from the gas tap 4.

In order to remove the ball 6 from the pipe 6, the chamber 20 is reconnected to the gas tap 4 and a vacuum pump is connected to the valve 24 say (both valves 24,25 being closed at this stage). The gas tap 4 is opened and then the valve 24 is opened to cause the ball 6 to be sucked out from the service pipe 5 into the chamber 20. The gas tap 4 is then closed and the chamber 20 removed from the gas tap 4.

The method described enables the consumer to be cut off at a point outside the consumer's premises without the need to excavate whether the cut off is temporary or permanent. Where the cut-off may be temporary, reconnection can be made quite simply from within the consumer's premises once again obviating the need for excavation.

Claims

1. A method for temporarily or permanently blocking the bore of a pipe through which fluid flows, the method comprising gaining access to the bore of the pipe at a suitable point, inserting into the pipe at the point a compressible seal which is adapted to form within the bore of the pipe a force fit sufficient to resist any attempt to dislodge it by the pressure of the fluid and forcing the seal along the pipe counter to the direction of fluid flow to a position along the length of pipe upstream of the suitable point.

2. A method as claimed in claim 1 in which the position is predetermined.

3. A method as claimed in claim 1 or claim 2 in which the suitable point is an end of the pipe.

4. A method as claimed in claim 3 in which the end terminates in a valve through which the seal is forced into the pipe.

5. A method as claimed in any of claims 1 to 4 in which the seal is forced along the pipe by means of the pressure of a fluid similar to that flowing in the pipe.

6. A method as claimed in any of the preceding claims in which the seal comprises a resilient ball.

7. A method substantially as hereinbefore described with reference to the accompanying drawings.

8. Apparatus for temporarily or permanently blocking the bore of a pipe through which fluid flows, the apparatus comprising a compressible seal for insertion into the pipe at a suitable point, the seal being adapted to form within the bore of the pipe a force fit sufficient to resist any attempt to dislodge it by the pressure of the fluid and means for forcing the seal along the pipe counter to the direction of fluid flow to a position within the pipe upstream of the suitable point.

9. Apparatus as claimed in claim 8 in which the resilient seal comprises a resilient ball.

10. Apparatus as claimed in claim 9 in which means are provided to limit the distance travelled by the ball along the pipe.

11. Apparatus as claimed in claim 10 in which the distance limiting means comprises a cable, the ball having means for releasably connecting the ball to the cable.

12. Apparatus as claimed in claim 11 in which the means for releasably connecting the ball to the cable comprises an internally threaded bush and the cable has an externally threaded end for connection to the bush.

13. Apparatus as claimed in claim 11 or claim 12 in which a stop is provided for connection to the cable, the stop being movable along the length of the cable following the ball whereby to limit the distance travelled by the ball along the pipe.

14. Apparatus as claimed in any of claims 8 to 13 in which the means for forcing the seal along the pipe comprises a chamber for temporarily housing the seal, the chamber having one end adapted for connection to an outlet end of the pipe and another end for connection to a suitable source of compressed gas whereby with the ball housed within the chamber while the one end is connected to the pipe outlet and the another end is connected to the compressed gas the ball may be expelled from the chamber and force along the pipe counter to the direction of fluid flow if the pressure of the compressed gas is greater than that of the fluid.

15. Apparatus substantially as hereinbefore described with reference to the drawings.

16. A compressible seal for use in the method claimed in claim 1, the seal comprising a resilient ball incorporating means permitting the ball to be releasably connected to a cable.

17. A seal as claimed in claim 16 in which the means comprises an internally threaded bush for connection to the externally threaded end of a cable.

18. A seal substantially as hereinbefore described with reference to Figure 3.

19. A resilient ball incorporating means permitting the ball to be releasably connected to a cable.

20. A ball as claimed in claim 19 in which the means comprises an internally threaded bush for connection to the externally threaded end of a cable.