GB2031161A - Pipe testing - Google Patents

Abstract

The invention relates to the leak testing of pipes, e.g. the pipes of a cooler block and the junctions between the pipes and the end plates of the blocks. A method of testing pipes and so on uses means (10) in which a sealing ring (11) is applied to each end of a pipe, the sealing ring (11) having a diameter greater than that of the pipe and abutting a plate secured to the pipe, the pipe is filled with water and the outlet end closed when air has been exhausted, following which the water pressure in the pipe is increased to a pre-set level and the water inlet closed. Any leakage from the pipe or from the pipe joint is detected by falling pressure in the pipe, which is, e.g., visually displayed on a pressure gauge. <IMAGE>

Description

SPECIFICATION Pipe testing This invention relates to a method of, and apparatus for testing oipes and in particular to the pipes incorporated in cooler blocks as are employed during the manufacture of liquified gas.

Such cooler blocks comprise two spaced apart end plates, e.g., of 2" thick steel of rectangular shape (although circular end plates are sometimes employed) between which end plates extend a plurality (e.g., several hundred) of parallel tubes of, e.g., copper or brass carrying around their outer peripheries tinned foil for heat dissipation purposes. In use cooling water is passed through these tubes and it is highly desirable to avoid leakage especially where the tube ends enter holes in the end plates, which locations are particularly susceptible to leakage, the ends usually being expanded slightly after insertion in a hole, for the tube external periphery to be deformed into two shallow annular grooves provided around the inside of the holes.

According to the present invention, a method of testing pipes secured between end plates, comprises applying to each end of the pipe, means incorporating a sealing ring, said sealing ring having a diameter greater than that of the pipe and abutting a plate-like member secured to each end of the pipe, filling the pipe with water and simultaneously exhausting air from the pipe, closing a shutoff valve at the outlet end of the pipe, increasing the water pressure in the pipe to a prescribed level, closing the water inlet to the pipe, and observing the pressure of the water in the pipe over a prescribed period.

By pressurizing the pipe, any fault such as a crack in the pipe itself will be detected as a consequence of the fall in pressure which may be visually displayed by providing a pressure gauge in association with the pipe, but what is of equal importance is that the joint between the pipe and the plate-like member secured to the pipe at each end is simultaneously tested by virtue of the fact that the sealing ring abuts the plate-like member beyond the outside diameter of the pipe and hence beyond the joint between the pipe and the plate-like members. Hitherto, whilst the pipes themselves have been tested with relative ease, considerable difficulty has been experienced in the testing of the joint between the pipe and the plate-like member.

Whilst pipes can be tested individually, it is highly advantageous, particularly when cooler blocks are under test, that more than one pipe can be tested at one time. In the case of cooler blocks, it will be recognised that the plate-like members secured to each end of the pipes are in fact the end plates of the cooler blocks themselves.

According to a further aspect of the invention, a method of testing a plurality of pipes in a cooler block comprises applying sealing means at each end of each pipe to be tested, each sealing means having a sealing ring of greater diameter than the pipes, simultaneously filling the pipes to be tested with water from a manifold common to all pipes under test and simultaneously exhausting air from the pipes, closing all the pipes at the outlet ends thereof, increasing the water pressure to a prescribed level common to all pipes under test, closing the inlet supply of water to the manifold when the prescribed pressure has been reached, observing over a prescribed period of time the pressure in the pipes on a pressure gauge associated with each pipe under test and in the event of there being observed a pressure drop closing sequentially shut-off valves associated with the pipes at the inlet sides thereof until such,time as the closure of an inlet end valve halts the pressure drop thereby indicating a leakage in that particular pipe.

It may well be that more than one pipe in those being simultaneously tested exhibits a leak. In practice a pressure drop noted following the closure of the inlet to the manifold will reduce when an inlet valve to a first leaking pipe is closed, and the pressure drop will continue at a lower rate until such time as any second or subsequent leaking pipe is closed.

The advantage of sequentially closing of the valves at the inlet ends of the pipes is that in the event that only one pipe is leaking, the pressure drop halts when the inlet valve to that pipe is closed thereby making it unnecessary to continue closing the valves on the succeeding pipes.

The leak is then repaired and the testing process repeated to test the repaired pipe.

According to a still further aspect of the invention, first apparatus for use in carrying out the method defined above comprises two adaptors one to engage in the inlet and one to engage in the outlet end of a pipe to be tested, closure valves associated with the adaptors each adaptor having a sealing ring adapted to abut and seal against a plate-like member to which the pipe is secured at each end, a connection on the adaptor at the inlet end of a source of pressure water, and a pressure gauge communicating with the interior of the pipe. To allow for the testing of a plurality of pipes, a plurality of inlet end adaptors may be provided in a common frame, each connected to a common manifold for the supply of pressure water and there being closure valve means at the inlet to the manifold.Preferably all the adaptors at the outlet ends of the pipes are similarly connected to a common manifold to which can be secured an air outlet and which considerably assists in the exhausting of air from all the pipes. Thus, all the adaptors can simulta heously be placed in to contact with the corresponding pipe and rigidly held against the plate-like means to ensure the sealing connection between the adaptors and the plate-like members.

According to a still further aspect of the invention apparatus for carrying out the above defined method comprises a perforated water supply tube adapted to be passed through a pipe to be tested, support means for a sealing ring rigidly secured to the tube and adapted to engage the plate-like member at the end of the pipe, support means for a sealing ring at the inlet end of the pipe screw mounted on the tube at that end and connection means at that end of the tube for a source of pressure water via a valve closure means, and a pressure gauge connected to the tube. Thus, by admitting water to the tube, water passes through the perforations into the pipe, to fill the pipe and exhaust air therefrom and following which the outlet end of the tube can be closed and when the above defined method can proceed.To allow for the testing simultaneously of pipes, a multiplicity of tubes can be mounted on an appropriate frame and whereby each can be passed through its corresponding pipe, and following which the threaded sealing ring support members can be screwed on to a respective tube and when the sealing ring at each end of the pipe can be brought into positive engagement with the plate-like member at that end. The inlet to the tube can then be connected to a common manifold and when again the above described testing method can proceed. Again, it is preferred that the outlet end of each tube is connected to a common manifold to which is secured an air bleed to assist in the exhausting of air from the pipes to be tested.

Two embodiments of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of a first embodiment of apparatus for testing pipes; Figure 2 is a side elevation of the apparatus of Fig. 1; and Figure 3 is a side elevation of a second embodiment of apparatus for testing pipes.

In Figs. 1 and 2 apparatus for testing pipes comprises a header pipe 1 having a valved inlet 2 providing a common source of supply of water to a number of individual pipe testing apparatus 3. Each such apparatus 3 comprises a supply line 4 connected to the header 1 leading to a shut-off valve 5, the shut-off valve 5 being connected by way of a nipple 6 to a tee-junction 7 carrying a pressure gauge 8, the tee-junction 7 also being connected by a barrel nipple 9 to an adaptor 10 having a sealing ring 11 having a diameter greater than the outside diameter of the pipe to be tested.Thus, as is shown by Fig. 2 with the header supported by a frame 12, the testing apparatus according to the invention can be held against the end plate 1 3 of a cooler block 14 exhibiting a large array of individual pipes 15, with each adaptor engaged in a pipe 1 5 to be tested. Thus, with the opposite end of each pipe 1 5 to that engaged by an adaptor 10 engaged by a second adaptor (not shown) connected in similar manner to an outlet manifold (also not shown), the outlet manifold being provided with an air bleed.

The valve inlet to the header 1 is opened and each valve 5 opened so that water can pass through each pipe 1 5 under test. Once air ih the pipes has been eliminated the air bleed is closed and each pipe pressurised to a predetermined degree following which the valve 2 is closed. If any one or more pipes simultaneously under test have a leak, there will be an inevitable loss of water pressure and which will be shown by the pressure gauges 8. To determine which one or more pipes of those under test has a leak, each pipe can be isolated in turn by closing the valve 5. If but one pipe of those under test has a leak, then when the valve 5 of the apparatus connected to that pipe is closed the pressure drop registering on the remaining pipes will cease.If more than one pipe has a leak, closure of the valve 5 on a first pipe will cause the pressure drop to continue at a lower rate until such time as any second or subsequent leaking pipe is closed. Once pipes in one row of the cooler block have been tested, the whole array can then be lowered to the next row of pipes and the above procedure repeated.

In the alternative apparatus shown in Fig.

3, the testing apparatus is provided by a perforated tube 1 6 extending through a pipe 1 7 to be tested. At the outlet side, an adaptor 18 is provided secured to the tube 16, e.g., by welding, and at the inlet side a second adaptor 1 9 is provided in screw-threaded engagement with the tube 16. Thus, with the tube inserted through the pipe, until the adaptor 1 8 attaches the end plate 20, the adaptor 1 9 is screwed on to the tube 1 6 until it attaches the end plate 21 to lock the tube 16 in position. Preferably a lock-nut 22 is provided to hold the adaptor 1 9 in place.A teejunction 23 is then secured in place, e.g., by screwing on to the end of the tube 16, the tee-junction having a valved inlet 24 for the supply of pressure water and a pressure gauge 25. With the inlet 24 connected to a source of pressure water, the valve is opened, water passing through the perforations in the tube 1 6 to fill the pipe 1 7. At the outlet end, the tube 1 6 is provided with an air vent 26 which is left open until such time as all air has been driven from the pipe 1 7. Following this the air valve is closed and the pipe 1 7 pressurised to a predetermined degree, following which the valve at the inlet 24 is closed. Any leak in the pipe 1 7 will thus be detected by a pressure drop shown on the pressure gauge.

The apparatus of Fig. 3 is shown testing an individual pipe. It will however be fully understood that a number of tubes 1 6 can be provided each connected to an appropriate header to allow the testing of a multiplicity of pipes after the manner of the apparatus of Figs. 1 and 2. It will equally be understood that the apparatus 3 of Figs. 1 and 2 could be used to test an individual pipe.

Claims (11)

1. A method of testing pipes secured between end plates, comprising applying to each end of the pipe, means incorporating a sealing ring, said sealing ring having a diameter greater than that of the pipe and abutting a plate-like member secured to each end of the pipe, filling the pipe with water and simultaneously exhausting air from the pipe, closing a shut-off valve at the outlet end of the pipe, increasing the water pressure in the pipe to a prescribed level, closing the water inlet to the pipe, and observing the pressure of the water in the pipe over a prescribed period.

2. A method as in Claim 1, wherein a method of testing a plurality of pipes in a cooler block comprises applying sealing means at each end of each pipe to be tested, each sealing means having a sealing ring of greater diameter than the pipes, simultaneously filling the pipes to be tested with water from a manifold common to all pipes under test and simultaneously exhausting air from the pipes, closing all the pipes at the outlet ends thereof, increasing the water pressure to a prescribed level common to all pipes under test, closing the inlet supply of water to the manifold when the prescribed pressure has been reached, observing over a prescribed period of time the pressure in the pipes on a pressure gauge associated with each pipe under test and in the event of there being observed a pressure drop closing sequentially shut-off valves associated with the pipes at the inlet sides thereof until such time as the closure of an inlet end valve halts the pressure drop thereby indicating a leakage in that particular pipe.

3. Apparatus for carrying out the method of Claim 1 comprising two adaptors one to engage in the inlet and one to engage in the outlet end of the pipe to be tested, closure valves associated with the adaptors each adaptor having a sealing ring adapted to abut and seal against a plate-like member to which the pipe is secured at each end, a connection on the adaptor at the inlet end of a source of pressure water, and a pressure gauge communicating with the interior of the pipe.

4. Apparatus as in Claim 3 for testing a plurality of pipes, comprising a plurality of inlet end adaptors provided in a common frame each being connected to a common manifold for the supply of pressure water and there being closure valve means at the inlet to the manifold.

5. Apparatus as in Claim 4, wherein all the adaptors at the outlet ends of the pipes are similarly connected to a common manifold to which is secured an air outlet.

6. Apparatus for carrying out the method of Claim 3, comprising a perforated water supply tube adapted to be passed through a pipe to be tested, support means for a sealing ring rigidly secured to the tube and adapted to engage the plate-like member at the end of the pipe, support means for a sealing ring at the inlet end of the pipe screw mounted on the tube at that end and connection means at that end of the tube for a source of pressure water via a valve closure means, and a pressure gauge connected to the tube.

7. Apparatus as in Claim 6, wherein a multiplicity of tubes are mounted in a common frame and whereby each can be passed through a corresponding pipe, each tube being connected to a common manifold for the supply of pressure water.

8. Apparatus as in Claim 7, wherein the outlet end of each tube is connected to a common manifold to which is secured an air bleed.

9. A method of testing pipes substantially as hereinbefore described with reference to Figs. 1 and 2.

1 0. A method of testing pipes substantially as herein before described with reference to Fig. 3.

11. Apparatus for performing the method of Claim 1 and substantially as hereinbefore described with reference to Figs. 1 and 2.

1 2. Apparatus for performing the method of Claim 1 and substantially as hereinbefore described with reference to Fig. 3.