GB1593434A

GB1593434A - Civil engineering pipe testing method

Info

Publication number: GB1593434A
Application number: GB2423577A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-07-15

Description

(54) CIVIL ENGINEERING PIPE TESTING METHOD (71) I, DAWAYNE CHARLES MIL LARD, a citizen of the United States of America, of 25 Mears Ashby Road, Sywell, Northampton, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to a method of testing a length of pipe in civil engineering applications.

When laying a pipe, which is intended for carrying water or sewage for example, it is necessary to lay successive lengths of pipe in end-to-end formation and to effect satisfactory seals between the adjoining lengths: it is necessary to test the integrity of these seals as the pipe grows in length. It is common to carry out this test by closing opposite ends of the pipe, from time-to-time as the pipe grows in length, pumping air into the closed length of pipe and then with the aid of a manometer, determining whether the air pressure within the closed length of pipe remains at its raised level or whether it falls (indicating whether the integrity of the pipe seals is maintained or not).

The conventional device for closing the pipe, which may be up to some 2 metres in diameter, comprises a solid rubber ring disposed between two heavy metal discs and a screw threaded accessory for driving the discs towards each other to axially compress the rubber ring, having the effect or radially expanding the rubber ring into sealing engagement with the inner surface of the pipe.

This device is however heavy and cumbersome, which are particular drawbacks when, as often is the case, the device must be man-handled down into trenches or through man-holes or other constricted spaces. Also, the device requires considerable manual force to operate.

The present invention provides a method of testing a length of pipe in civil engineering applications, comprising installing respective sealing devices in opposite ends of the pipe to be tested, inflating an inflatable ring of each device to seal against the inner circumference of the pipe, each ring having its central aperture sealed over, raising the pressure in the length of pipe between the two sealing devices, and thereafter monitoring any reduction in said pressure. In embodiments to be illustrated and described herein, the central aperture of the ring of each sealing device is sealed over by a flexible means and the ring is itself formed of flexible material so that the entire device is flexible and light in weight and therefore easy to carry to the site at which it is to be used.Conveniently, the ring of each sealing device may be made of rubber and the central aperture sealed over by a rubber membrane which is vulcanised around its edge to the ring itself.

Embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings, in which: Figure 1 is a front elevation of a sealing devce, when in inflated condition, for use in closing a pipe by a method in accordance with this invention, Figure 2 is a longitudinal section through a portion of pipe sealed by a said sealing device which is slightly modified from that shown in Figure 1, this modified device being shown in cross-section; Figure 3 is a cross-section through a sealing device intended for smaller diameter pipes or tubes; and Figure 4 is a front elevation of a supporting frame for use in conjunction with the sealing devices.

Referring to Figures 1 and 2, the sealing device comprises a hollow rubber ring 1 provided with a valve 2 through which air may be pumped, for example by a hand or foot pump, to inflate the ring, and through which air may subsequently be allowed to escape to deflate the ring. As shown, the ring has a natural circular shape in the inflated condition. The central aperture of the ring is closed by two circular rubber membranes 3, 13 which are vulcanised around their peripheries 3a, 13a to the ring itself, the two membranes being applied to opposite sides of the ring so that a space 4 exists between the membranes. The peripheries 3a, 13a of the membranes are spaced somewhat, about 3 inches, radially from the outer periphery of the ring. Each membrane comprises a layer of rubber with a cotton or nylon mesh embedded therein for reinforcement.

Two tubes 5, 6 extend through the two membranes, each tube being sealed to both membranes. The tube 5 includes an inlet valve Sa, such as a Schrader (Registered Trade Mark) valve, at one end and the adjacent end of the tube 6 is adapted for connection to a rubber tube leading to a manometer. The tube 5 serves to admit air into the length of pipe being tested and the manometcr which, in use, is connected to tube 6 serves as a gauge of the pressure of the air in that length of pipe. The membrane 13 is provided with a valve 7 for admitting air to the space between the membanes, for a purpose to be described below.

In use, the scaling device is carried to the required site and placed in the end of the pipe 8 which is to be tested. The ring is then inflated using a hand or foot pump, typically to perhaps 10-20 Ibs/sq inch, sufficiently for the ring to seal against the inner surface of the pipe 8. A second such device is installed at the opposite end of the pipe to be tested.

Then, air is pumped into this length of pipe through the valved tube 5 of one of the devices, in order to raise the pressure in this length. A manometer is coupled to the tube 6 of the same device and is used to monitor any fall in pressure, indicative of some leak in the length of pipe under test. After the test, it is a simple matter to deflate and remove the device.

If a leak is detected, it may be desirable to check that this does not occur through the membranes of the sealing devices. In order to carry this out, air is pumped into the space 4 through the valve 7, with the result that the membranes bulge outwardly. If the visible membrane remains bulged, then the leak is not through the membranes of that sealing device, but if that membrane loses its bulge, then this indicates a leak through the membranes of that device.

In Figure 2, a modified sealing device is shown, comprising an extruded strip of rubber 9 which has been placed to extend around the periphery of the ring 1 and which has been vulcanised directly to the ring. One surface of the rubber strip 9 is transversely curved to conform to the surface of the ring, which is circular in section, as shown in Figure 2. The opposite surface of the rubber strip 9 is relatively flat, transversely, with the effect of increasing the surface area which seals against the inner surface of the pipe 8. The rubber strip also serves to protect the rubber ring against abrasion, and hence puncture, from the pipe.

Instead of two membranes, it is possible to provide only a single such membrane and this modification is shown in Figure 3. The device shown in Figure 3 is intended for smaller diameter pipes and the ring 1 is flatter in section, providing more surface area for sealing against the pipe. A second membrane may be provided in this device, as shown by dotted lines at 13. The device shown in Figure 3 is able to serve a range of different pipe diameters, typically 15-18 inches, because it can be inflated to match the diameter of pipe into which it is inserted. The devices shown in Figures 1 and 2 are for larger diameter pipes, in the range 2-4 (possibly 2-6) feet diameter, and different sizes of devices are needed for different sizes of pipes.

Since the pipe to be tested may be made of concrete or other relatively abrasive material, the material from which the ring 1, or the ring 1 and membrane 3, is made should be appropriately wear-resistant or alternatively the ring, or ring and membrane, should be covered with a resistant covering, for example canvas. Any suitable alternative to to rubber may be used, providing it is flexible and impervious to air.

Although it is common to test pipes at about 50 metre lengths, there is a tendency to test lengths up to 200 metres and the sealing devices described above may be used for this. However, for the longer lengths, and for the larger diameters, it is preferred to use the devices in conjunction with a support frame as shown in Figure 4, which serves to prevent the sealing device being forced along the pipe under the pressure of air in the length of pipe under test. The frame may in fact be used on all occasions.

The supporting frame comprises two main lengths 20, 21 of metal tube with rubber wheels 22 journalled to their opposite ends.

The frame further comprises two collapsible links, each link comprising a length 23 of metal tube having one of its ends pivoted, adjacent one end of main length 20, and a length 24 of metal tube having one of its ends pivoted adjacent one end of main length 21. The two link lengths 23, 24 are pivoted together at their other ends, one of them including a screw adjustment for adjusting its effective length.

In collapsed condition, the links pivot to the positions shown in dotted lines, bringing the two main lengths 20, 21 closer together.

In such condition, the frame may be introduced into the pipe to be tested and then erected, in contact with the sealing device, by moving the main lengths apart and forcing the links until the two portions of each link are in a straight line. If the length-adjustment or the links is correct, the wheels 22 will now be firmly pressed against the inner surface of the pipe and deformed to the shape of the surface of the pipe.

Sleeves 25 are provided for sliding over the joint between the two portions of each link to hold the link straight. The frame, now firmly in position, is able to support the sealing device.

In a modification, particularly for the larger diameter pipes, the sealing device may comprise two circular, flexible membranes which are sealed together around their peripheries: each membrane has a disc of fibre glass (or other light-weight material) secured at its centre and the two discs are clamped together. Thus an inflatable ring is formed between the two membranes, and between the two discs and the sealed peripheries of the two membranes. The tubes, 5, 6 pass through the two discs.

WHAT WE CLAIM IS: 1. A method of testing a length of pipe in civil engineering applications, comprising installing respective sealing devices in opposite ends of the pipe to be tested, inflating an inflatable ring of each device to seal against the inner circumference of the pipe, each ring having its central aperture sealed over, raising the pressure in the length of pipe between the two sealing devices, and thereafter monitoring any reduction in said pressure.

2. A method as claimed in claim 1, in which the central aperture of each sealing device is sealed over by a flexible means.

3. A method as claimed in claim 2 in which the ring itself of each sealing device is flexible.

4. A method as claimed in claim 3, in which the material of the ring of each sealing device is rubber.

5. A method as clained in any one of claims 2 to 4, in which the flexible means of each sealing device comprises a circular membrane secured sealingly around its periphery to the respective ring.

6. A method as claimed in any one of claims 2 to 4, in which the flexible means of each sealing device comprises two circular membranes secured sealingly around their peripheries to opposite sides of the ring.

7. A method as claimed in any preceding claim, comprising a valve provided on the ring of each sealing device, for admitting air to the ring for inflation and subsequently allowing air out of the ring for deflation.

8. A method as claimed in any preceding claim, comprising a valved tube extending through the sealed-over central aperture of the ring of each sealing device.

9. A method as claimed in any preceding claim, comprising a second tube extending through the sealed-over central aperture in the ring of each sealing device.

10. A method as claimed in claim 6 or any one of claims 7 to 9 when appended to claim 6, comprising a valved inlet to the space between the two membranes of each sealing device.

11. A method as claimed in any preceding claim, further comprising a strip of rubber secured to the ring of each sealing device and extending around the outer periphery thereof.

12. A method as claimed in any preceding claim, comprising erecting a support against each sealing device to prevent it being moved by the raised air pressure.

13. A method as claimed in claim 12, in which each support frame comprises two elongate members and two hinged links, each link havings its opposite ends pivoted to the respective elongate members adjacent their ends, the elongate members being movable apart upon hinging the links from collapsed positions to straight positions, and means for holding the links straight.

14. A method as claimed in claim 13, in which said holding means of each support frame comprises respective sleeves, each slidable along its link to embrace the hinged portions thereof.

15. A method as claimed in claim 13 or 14, in which the opposite ends of each said elongate member of each support frame are provided with rubber wheels.

16. A method of testing a length of pipe, substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. In such condition, the frame may be introduced into the pipe to be tested and then erected, in contact with the sealing device, by moving the main lengths apart and forcing the links until the two portions of each link are in a straight line. If the length-adjustment or the links is correct, the wheels 22 will now be firmly pressed against the inner surface of the pipe and deformed to the shape of the surface of the pipe. Sleeves 25 are provided for sliding over the joint between the two portions of each link to hold the link straight. The frame, now firmly in position, is able to support the sealing device. In a modification, particularly for the larger diameter pipes, the sealing device may comprise two circular, flexible membranes which are sealed together around their peripheries: each membrane has a disc of fibre glass (or other light-weight material) secured at its centre and the two discs are clamped together. Thus an inflatable ring is formed between the two membranes, and between the two discs and the sealed peripheries of the two membranes. The tubes, 5, 6 pass through the two discs. WHAT WE CLAIM IS:

1. A method of testing a length of pipe in civil engineering applications, comprising installing respective sealing devices in opposite ends of the pipe to be tested, inflating an inflatable ring of each device to seal against the inner circumference of the pipe, each ring having its central aperture sealed over, raising the pressure in the length of pipe between the two sealing devices, and thereafter monitoring any reduction in said pressure.