GB2167830A - Pipe sealing device - Google Patents

Abstract

A device for sealing the end of, for example, a gas pipe (10) including a normally convoluted rubber tube (18) attached to a rigid tube (20) through which passes a rod (21) which may be advanced to extend tube (18) longitudinally thus temporarily reducing its lateral dimension to permit passage through a valve aperture (13). Once inside the pipe, tube (18) is released so that it expands into sealing contact with the pipe wall. Valve plug (12) maybe closed to sever tube (20) and rod (21), and valve (11) may be removed without gas escaping from pipe (10). The device may be subsequently removed using an appropriate tool. <IMAGE>

Description

SPECIFICATION Pipe sealing device This invention concerns a device for sealing a pipe end to prevent ingress or egress of fluid thereat, and is particularly, though not exclusively concerned with a device which can be inserted into a gas pipe to suspend the supply of gas therefrom, either temporarily or semipermanently, for example, in the event of a service being discontinued, or to enable a gas cock or valve mounted on the end of the pipe, to be replaced with safety.

It is important that such a device when used for temporary suspension of the supply, can be inserted and removed by unskilled or semi-skilled personnel, with complete safety.

Removal of the semi-permanent form of the device without the proper equipment should be impossible or at least very difficult. The device should be inert to the gas or other fluid to which it is to be subjected and should be sufficiently durable to withstand minor surface damage which may be caused by sharp obstructions within the pipe end.

The prior art includes devices such as expandible plugs which are compressed once inserted in the pipe thus to expand and seal against the internal wall surface thereof, and inflatable bladders which are inflated after insertion. Such devices have been largely unsuccessful and have been found to be susceptable to leakage.

An object of the present invention is to provide a device which fulfils operational and safety requirements, whilst being simple and inexpensive in manufacture and use.

According to the present invention there is provided a device for sealing a pipe end to prevent ingress or egress of fluid thereat, comprising an elongate flexible and resilient member which, in a relaxed or non-stressed state, is selected to have a lateral dimension greater than the cross-section of a pipe to be sealed, and means to cause said member temporarily to be enlarged longitudinally and reduced laterally to permit insertion into or removal from the pipe.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates, partly in cross-section a device made in accordance with the invention ready for introduction through a stop-valve into a pipe end; and Figure 2 is a similar view showing the device inserted.

Referring now to the drawings, there is illustrated in Fig. 1 a pipe 10 having a stop valve 11 mounted on the open end thereof. The valve in this example is of the type having a rotatable tapered plug 12 with a central aperture 13 which becomes aligned with the bore 14 of the valve body 15 upon rotation of the plug 12 about axis 16. The body 15 is threaded externally at 17 for attachment to, for example, a gas supply meter.

A sealing device made in accordance with the invention consists of a normally convoluted rubber tube 18 of a flexible and resilient material, which, in a relaxed or non-stressed state assumes the shape illustrated in Fig. 2 and preferably is manufactured from nitrile rubber. The tube 18 is closed at one end as indicated at 19. The other end of tube 18 is open and is bonded to a rigid nylon tube 20.

A rigid nylon probe or rod 21 which may be tubular extends internally through rigid tube 20 and has on its outer end a cap 22. The opposite end of rod 21 extends within the rubber tube 18 such that the end is bonded internally to the end of the latter at 24.

The device may also include a rubber or resilient plastics cap 25 threaded internally or configured to be a push fit over threaded portion 17 of valve body 15, and to having a central bore through which rubber tube 18 and rigid tube 23 may pass. The internal configuration of cap 25 preferably includes ribs 26 which ensure a substantially gas tight seal for the passage of tubes 18 and 20.

In use therefore, assuming it is intended to replace valve 11, and with the existing valve closed, cap 25 is placed in the position shown in Fig. 1, and with rod 21 inserted to elongate and stretch tube 18 as shown, the latter may be inserted into cap 25, and the valve plug 12 subsequently rotated to open the valve.

The device is then advanced until the entire length of rubber tube 18 is within the pipe 10. If, then, the rod 21 is withdrawn or permitted to withdraw through tube 20, rubber tube 18 is permitted to relax towards its natural convoluted form, as shown in Fig. 2. In this condition, the tube 18 frictionally engages and seals against the internal wall surface of pipe 10, and gas is prevented from escaping so that valve 11 can be removed from the pipe.

Tube 18 may be subsequently extracted by a procedure which is the reverse of that just described. This consists essentially of extending rod 21 through tube 20 to elongate tube 18, thus permitting its removal through valve aperture 13.

In some cases it may be preferable to include a catch mechanism enabling rod 21 to be retained temporarily in its extended position without being continuously held by the operator.

In cases where temporary escape of gas can be tolerated, cap 25 may be omitted, and tube 18 inserted into the pipe after removal of valve.

It will be appreciated that the sealing device is intended to prevent escape of gas or liquid at moderate pressures, i.e. in the region of 75 millibars or less.

If the device is intended to provide a permanent or semi-permanent closure, and valve 11 is to remain in place, then once the device is inserted valve plug 12 can be rotated to the closed position thus severing external and internal plastics tubes, these being removable subsequently if required after removal of valve 11.

The convolutions naturally assumed by tube 18 can be of different diameters increasing in size from the leading end so that the device can be used to seal a number of different sized pipes. It has been established that in most cases the sealing contact of one convolution is sufficient for the purpose. Indeed, whilst the device has been designed principally for gas pipes wherein the pressure is no greater than 75 millibars, in experimental tests the device has been found to maintain a seal at a pressure of 300 millibars, and infact the sealing effect is increased as a result of the fluid pressure tending to force the outer extremity of the leading convolution into firm contact with the wall surface of the pipe.

It is not intended to limit the invention to the above example only. For example, tube 18 may be removably attached, to tube 20 which may be manufactured from mild steel or brass, for example. In this case, the tubes 20 and 21 may be removed once tube 18 has been inserted in the pipe so that nothing is left protruding from the pipe end.

Claims (10)

1. A device for sealing a pipe end to prevent ingress or egress of fluid thereat, comprising an elongate flexible and resilient member which, in a relaxed or non-stressed state, is selected to have a lateral dimension greater than the cross-section of a pipe to be sealed, and means to cause said member temporarily to be enlarged longitudinally and reduced laterally to permit insertion into or removal from the pipe.

2. A device according to Claim 1, in which said elongate flexible and resilient member comprises a normally convoluted rubber tube which, in said relaxed or non-stressed state is configured to have a plurality of aligned convolutions.

3. A device according to Claim 2, in which said convolutions are of different diameters such that the device can be used to seal a number of different sized pipes.

4. A device according to any preceding claim, in which said temporary enlarging means includes a rod which is retractably extended within said elongate flexible and resilient member.

5. A device according to any preceding claim, wherein said temporary enlarging means is removable from said elongate flexible and resilient member thus to leave same alone once inserted within a pipe.

6. A device according to any preceding claim, wherein said temporary enlarging means comprises a pair of co-axial plastics tubes, the outer attached to one end of the said elongate flexible and resilient member, the inner extending through said elongate flexible and resilient member and bonded internally thereto.

7. A device according to any preceding claim, including an end cap for attachment to a pipe end to be sealed, and having a central bore through which said temporary enlarging means and said elongate flexible and resilient member when enlarged thereby, may pass, and at least one sealing rib providing a substantially gas-tight seal around the latter.

8. A device according to any preceding claim, including a catch mechanism associated with said temporary enlarging means whereby said elongate flexible and resilient member may be maintained in its longitudinally enlarged state.

9. A device according to any preceding claim, wherein the elongate flexible and resilient member is made from nitrile rubber.

10. A device for sealing a pipe end, substantially as hereinbefore described, with reference to, and as illustrated in, the accompanying drawings.