GB2345329A

GB2345329A - Plastics pipe with channel for detecting leakage

Info

Publication number: GB2345329A
Application number: GB9923036A
Authority: GB
Inventors: Marcus Hawerkamp
Original assignee: BAUKU TROISDORFER BAU und KUNS
Current assignee: BAUKU TROISDORFER BAU und KUNS
Priority date: 1998-12-19
Filing date: 1999-09-30
Publication date: 2000-07-05
Anticipated expiration: 2019-09-30
Also published as: GB9923036D0; DE19858915C5; FR2787552B1; GB2345329B; FR2787552A1; DE19858915C1

Abstract

A pipe (1), particularly a wound pipe made of plastics material, has a leakage channel (4) which runs spirally in the pipe wall (2) with the formation of leakage channel windings (3). The leakage channel (4) is acted upon by an overpressure and comprises at least one leakage detector constructed as a pressure variation detector. At least one first connecting channel (6), which extends over the entire pipe length with its axis approximately parallel to the pipe axis (5) and which connects the leakage channel windings (3), is disposed in the pipe wall (2). The leakage liquid can thus be removed from the leakage channel, even after the occurrence of damage, so that the leakage detector device operates perfectly again after reconstruction. Pipes according to the invention may be joined to each other at their end faces to form a pipeline.

Description

2345329 "PLASTICS PIPE" This invention relates to a pipe, particularly a

wound pipe made of plastics material, having a leakage channel which runs spirally in the pipe wall with the formation of leakage channel windings, wherein the leakage channel is acted upon by an overpressure and comprises at least one leakage detector constructed as a pressure variation detector.

Wound pipes of this type are fabricated from wound hollow sections produced by a plastics extrusion method, for example. The wound hollow sections have a rectangular or square external cross-section. The wound pipe is produced by winding these wound hollow sections spirally and close together, wherein the cavity in the wound hollow sections, which is generally of round cross-section, forms the leakage channel. In a vertical arrangement and with a base, wound pipes can be used as liquid containers (see DE 44 10 593). Secondly, in a horizontal or sloping arrangement, wound pipes are employed as liquid channels, e.g. as waste water ducts.

Wound pipes are distinguished by their high stability and by the possibility which they provide of readily monitoring leaks. A crack which propagates from the inner face or the outer face of the pipe inevitably encounters the spirally extending leakage channel. The resulting pressure drop inside the leakage channel is recorded by the pressure variation detector. Within the scope of the present invention, it is possible in principle for the leakage channel to be acted upon by a reduced pressure. A pressure increase is then recorded by the pressure variation detector in the event of a leak. Known wound pipes have been proven in practice. The problem arises however, particularly for a horizontal or slightly sloping arrangement of wound pipes, that any leakage liquid which enters the leakage channel can only be removed with difficulty from the leakage channel, even after the leak has been sealed, because the liquid accumulates in the leakage channel windings in the lowest region of the pipe or duct. Even if the leakage channel is acted upon by an overpressure, it is very probable that in the event of damage liquid will enter the leakage channel from the outside or from the inside. In fact, this does not at first adversely affect the recording of the damage, since the leakage detector device reacts to pressure variations inside the leakage channel. After repairing the damage, however, it is almost impossible to set the monitoring system in operation again. This is because there is a liquid/air mixture in the leakage channel, which results in conditions which can only be controlled with difficulty as regards further leakage monitoring, since the air is compressible but the liquid is generally incompressible. It is then rarely possible to effect reliable leakage monitoring by means of leakage detector devices which are constructed as pressure variation detectors. Moreover, a relatively sluggish equalisation of pressure occurs over the spiral leakage channel, which is generally of a considerable total length, of known wound pipes. During the fabrication of wound pipes, or even when joining a plurality of wound pipes in the course of assembly, constrictions of the leakage channels or even the complete closure thereof can occur. In this situation also, it is no longer possible to effect reliable leakage monitoring, since pressure variations in one region of the leakage channel are not detected by a pressure variation detector which may be at a considerable distance therefrom.

A basic object of the present invention is to create a pipe, particularly a wound pipe made of plastics material, of the form of construction described at the outset, which is constructed in a reliable and stable manner and which enables leakage monitoring to be effected reliably, even after a repair has been carried out on the wound pipe as a result of a leak.

According to the present invention, there is provided a pipe, particularly a wound pipe made of plastics material, having a leakage channel which runs spirally in the pipe wall with the formation of leakage channel windings, wherein the leakage channel is acted upon by an overpressure and comprises at least one leakage detector constructed as a pressure variation detector, wherein at least one first connecting channel, which extends over the entire pipe length with its axis approximately parallel to the pipe axis and which connects the leakage channel windings, is disposed in the pipe wall.

The invention stems from the recognition that the disadvantages of known wound pipes which were cited at the outset can surprisingly be avoided if a connecting channel, which serves as a transverse connection as it were, is provided between the leakage windings. In a horizontal or slightly sloping arrangement of the wound pipes according to the invention, the first connecting channel which connects the leakage channel windings serves as a drainage channel in the region of the lowest point of the pipe. If there is leakage liquid in the leakage channel as a result of a leak, this leakage liquid flows off via the drainage channel disposed at the lowest point of the pipe or is removed by suction. Thus, after the leak is sealed, there is no longer any liquid in the leakage channel, so that the leakage detector device also continues to operate perfectly. As a result, it is possible to effect reconstruction in a particularly simple and reliable manner after the occurrence of damage. Even constrictions or closures in the region of the leakage channel windings no longer result in operating problems, since a direct connection always exists between the leakage channel windings via the first connecting channel. Moreover, the response time of the leakage monitoring system is shortened considerably by the connecting channel between the leakage channel windings. In principle, it is no longer necessary to monitor an air column which amounts to a considerable overall length on account of the spiral leakage channels. Consequently, the connecting channel constitutes a bridge, as it were, via which the transport of air pressure variations can proceed significantly more rapidly. An operating error during the production of wound pipes by a plastics extrusion route or during the welding of wound pipes on site no longer results in an operating failure of the leakage monitoring system.

According to a further recommendation of the invention, a second connecting channel, which likewise extends with its axis approximately parallel to the pipe axis and which connects the leakage channel windings, is disposed in the region of the pipe wall which is opposite the first connecting channel. In a horizontal or slightly sloping arrangement of the wound pipes, the second connecting channel is situated in the region of the highest point of the container and serves as an aeration channel. In this manner, a reduced pressure is prevented from occurring in the region of the leakage channel or of the drainage channel in the course of the drainage or removal by suction of the leakage liquid.

Other preferred features of the invention are listed below. According to one preferred embodiment, at least the first connecting channel communicates tangentially with the leakage channel windings, in the outer region thereof facing away from the pipe axis. It is thus ensured that in a horizontal or slightly sloping arrangement of the pipe the lowest point of the first connecting channel is always disposed below the lowest point of the leakage channel, so that the whole of the leakage liquid reliably enters the first leakage channel or the connecting channel from the leakage channel windings. The connecting channels can be constructed as connecting bores.

In a further embodiment, the invention relates to a pipeline comprising at least two pipes of the type according to the invention which are joined to each other at their end faces. In this embodiment of the invention, the pipe walls comprise externally tapered end faces, and a circumferential groove, which is V-shaped over the longitudinal section of the pipe and into which the connecting channels lead, is formed in the region of abutment between the end faces, the pipe walls are joined to each other in the region of the circumferential groove which faces the pipe axis by a material bond or adhesively, and are preferably welded to each other, and the pipe walIs are surrounded, at least in the region of the V-shaped circumferential groove, by a sealing jacket), e.g. a socket sleeve or connecting sleeve, which blanks off the circumferential groove and which is joined to the pipe walls by a material bond or adhesively, and is preferably welded thereto. In this manner it is ensured that perfect drainage of the leakage liquid is possible even ifjoints are made between a multiplicity of pipes disposed in series. This is because the leakage liquid enters the drainage channel of a pipe, which leads into the circumferential groove in the region of abutment, via the leakage channel windings. From the circumferential groove, the liquid flows into the drainage channel of the adjacent pipe and flows further into the removal region. A connection between the spiral leakage channel of one pipe and the spiral leakage channel of the adjacent pipe is no longer necessary, because there is a direct connection via the connecting channels and the circumferential groove, which also ensures equalisation of pressure.

Compensation for tolerances during assembly, as it were, is ensured by the circumferential groove, since it is no longer necessary for the pipes to be aligned in a costly manner so that the leakage channels are exactly in alignment. As a result, assembly is considerably simplified, and at the same time the reliability of leakage monitoring in pipelines comprising a multiplicity of pipes is improved. In one advantageous embodiment of the invention, the V- shaped circumferential groove has an included angle a of 50' to 70' over the longitudinal section of the pipe.

The invention is explained in greater detail below with reference to the drawings, which merely illustrate an example of an embodiment, and where:

Figure I is a perspective view of part of a pipe according to the invention; and Figure 2 is a section taken in the longitudinal direction of the pipe through part of a pipeline comprising two pipes which are joined to each other at their end faces.

Figure I shows a wound pipe I made of plastics material, having a leakage channel 4 which runs spirally in the pipe wall 2 with the formation of leakage channel windings 3. The leakage channel 4 is acted upon by an overpressure and comprises at least one leakage detector constructed as a pressure variation detector, which is not illustrated in the Figures. A first connecting channel 6, which extends over the entire pipe length with its axis approximately parallel to the pipe axis 5 and which connects the leakage channel windings 3, is disposed in the pipe wall 2. A second connecting channel 7, which extends with its axis approximately parallel to the pipe axis 5 and which connects the leakage channel windings 3, is disposed in the region of the pipe wall 2 which is opposite the first connecting channel 6. In the embodiment exemplified, the wound pipe I is disposed slightly sloping in relation to the horizontal.

Accordingly, the first connecting channel 6 serves as a drainage channel, whilst the second connecting channel 7 serves as an aeration channel. If leakage liquid enters one of the leakage channel windings 3 of the leakage channel 4 as a result of a leak, the leakage liquid thus directly enters the first connecting channel 6 which is constructed as a drainage channel 6. Via the drainage channel, the leakage liquid flows into a shaft, which is not illustrated, into which the wound pipe 1 leads. The first connecting channel 6 communicates tangentially with the leakage channel windings 3, in the outer region thereof facing away from the pipe axis 5. The same applies to the second connecting channel 7.

Figure 2 shows a pipeline comprising two wound pipes I which are joined to each other at their end faces. It can be seen that the pipe walls 2 comprise externally tapered end faces 8 and that a circumferential groove 9, which is V-shaped over the longitudinal section of the pipe and into which the connecting channels 6, 7 lead, is formed in the region of abutment between the end faces 8. The pipe walls 2 are welded to each other in the region of the circumferential groove 9 which faces the pipe axis 5. In addition, the pipe walls 2 are surrounded in the region of the V shaped circumferential groove 9 by a sealing jacket 10 which blanks off the circumferential groove 9. In the embodiment exemplified, the sealing jacket is constructed as a socket sleeve 10.

The socket sleeve 10 is welded to the pipe walls. It can immediately be seen from Figure 2 that it is no longer necessary for the leakage channel windings 3 of one wound pipe I to communicate with the leakage channel windings 3 of the other wound pipe 1, because a connection between the leakage channels 4 exists in each case via the connecting channels 6, 7 and the circumferential groove 8. Consequently, the leakage liquid can flow via the drainage channel 6 of one wound pipe I into the circumferential groove 8, and can flow fiirther into the drainage channel 6 of the other wound pipe I - It can also be seen that the V- shaped circumferential groove 9 has an included angle a of about 5 0 0 over the longitudinal section of the pipe.

Claims

1. A pipe, particularly a wound pipe made of plastics material, having a leakage channel which runs spirally in the pipe wall with the formation of leakage channel windings, wherein the leakage channel is acted upon by an overpressure and comprises at least one leakage detector constructed as a pressure variation detector, wherein at least one first connecting channel, which extends over the entire pipe length with its axis approximately parallel to the pipe axis and which connects the leakage channel windings, is disposed in the pipe wall.

2. A pipe according to claim 1, wherein a second connecting channel, which extends with its axis approximately parallel to the pipe axis and which connects the leakage channel windings, is disposed in the region of the pipe wall which is opposite the first connecting channel.

3. A pipe according to claims I or 2, wherein at least the first connecting channel communicates tangentially with the leakage channel windings, in the outer region thereof facing away from the pipe axis.

4. A pipe according to any one of claims I to 3, wherein the connecting channels are constructed as connecting bores.

5. A pipe, particularly a wound pipe made of plastics material, substantially as herein before described with reference to the accompanying drawing(s).

6. A pipeline comprising at least two pipes according to any one of claims I to 5 which are joined to each other at their end faces, wherein the pipe walls comprise externally tapered end faces and that a circumferential groove, which is V-shaped over the longitudinal section of the pipe and into which the connecting channels lead, is formed in the region of abutment between the end faces, that the pipe walls are joined to each other in the region of the circumferential groove which faces the pipe axis by a material bond or adhesively, and are preferably welded to each other, and that the pipe walls are surrounded, at least in the region of the V-shaped circumferential groove, by a sealing jacket, e.g. a socket sleeve or connecting sleeve, which blanks off the circumferential groove and which is joined to the pipe walls by a material bond or adhesively, and which is preferably welded thereto.

7. A pipeline according to claim 5, wherein the V-shaped circumferential groove has an included angle a of 50' to 70' over the longitudinal section of the pipe.