GB2312726A

GB2312726A - Plastics pipes

Info

Publication number: GB2312726A
Application number: GB9609103A
Authority: GB
Inventors: Stephen Mcdermott
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-05-01
Filing date: 1996-05-01
Publication date: 1997-11-05
Also published as: GB9609103D0

Abstract

A utility pipe 10 ,to be laid underground, is composed of plastics material and having a metallic element 11 or composition extending continuously therealong to be traceable by a metal detector, e.g. by electrical inductive means. The element 11 is embedded or lies on the interior or exterior wall, e.g as a wire, coated if necessary. Alternatively, the composition is co-extruded and extends across a small arc or all around.

Description

PIPES DBSCRIPTION Background to the Invention This invention relates to pipes and in particular to pipes to be laid underground (hereinafter called "underground pipes") for utilities, i.e. use as conduits for electricity cables and/or for the transmission of water or gas.

Such underground utility pipes are laid underground at a depth of about 60 cm and currently are made of plastics material. Accordingly, once buried (i.e. laid underground), such underground utility pipes cannot be readily located other than by digging locating holes or trenches transversely across the likely path. These "trial and error" methods of detection are unduly time consuming, labour intensive and expensive, and it is accordingly considered desirable to provide underground utility pipes which can overcome these disadvantages.

Brief Descrintion of the Invention According to one aspect of this invention there is provided a utility pipe to be laid underground composed of plastics material and having a metallic element extending continuously therealong, the metallic element being traceable by a metal detector, e.g, electrical inductive means, when the pipe is buried underground.

Preferably the metallic element extends linearly generally parallel to the axis of the pipe. Alternatively it may be spiral wound in relation to the pipe axis.

The metallic element may be a wire bonded to the exterior of the pipe or, preferably for other than water pipe, to the interior of the pipe.

In one preferred embodiment, the element is embedded in the plastics material forming the pipe wall.

Alternatively the metallic element may be a metallic composition extruded with the plastics material so as to form the pipe wall therewith. The metallic composition can extend around 360 of the pipe's cross-sectional area or for a small arcuate extent, e.g. less than 60", of the pipe's cross-sectional area.

Brief Description of the Drawings By way of example one embodiment of this invention will now be described with reference to the accompanying drawings of which: Figure 1 is a schematic cross-sectional view through an underground water pipe according to a first embodiment of the invention, Figure 2 is a schematic cross-sectional view through an underground water pipe according to a second embodiment of the invention, Figure 3 is a schematic cross-sectional view through an underground water pipe according to a third embodiment of the invention, and Figure 4 is a schematic cross-sectional view through an underground water pipe according to a fourth embodiment of the invention.

The underground pipe 10 of Fig 1 is a water pipe of plastics material conforming to BS.6572:1985. It is extruded with an area of its wall in encompassing relation to a continuous metallic element in the form of a soft metal strip 11 that is pulled off a reel by the extrudate emanating from the extruder head. The arrangement is such that the metal strip 11 is embedded as a continuous metallic element within the wall of the pipe 10. When the pipe is buried, the metal strip 11 can be detected by a conventional metal detector or other inductive sensing means.

The underground water pipe 20 of Fig 2 is identical to the pipe 10 of Fig 1 save that in this embodiment the continuous metallic element is a metal wire 22 of circular cross-section (rather than the rectangular-section metallic strip 11 of Fig l).

The underground water pipe 40 of Fig 4 is similar to the pipe 20 of Fig 2 save that instead of an embedded wire 22 it has a metal wire 44 of circular cross-section bonded to the exterior surface of the wall of the pipe 40. If in the anticiapted use conditions the metal is potentially liable to rust, it may be encased in a plastics material sheath, the latter being bonded to the plastics material of the pipe.

In an alternative arrangement the metal wire 44 can be bonded to the interior surface of the pipe, and even if potentially liable to rust, may then not need to be encased in a plastics material sheath if the underground pipe is to be used for gas or for an electrical conduit.

The underground water pipe 30 of Fig 3 is produced by extruding through a two-part mold, one part extending arcuately through at least 3000 and the other part extending through up to 60e. The larger mold part is fed with plastics material (i.e. that conventionally used for producing plastics material pipes of the prior art) to produce the majority of the pipe wall, whilst the smaller mold part is fed with a metallic composition 33 that forms the remainder of the pipe wall and is bonded by its arcuate sides to the majority of the pipe wall.

Other modifications and embodiments of the invention will be readily apparent to those skilled in this art, and all such modifications and embodiments are to be deemed within the ambit and scope of the invention. Thus the invention is not to be deemed limited to the particular embodiment(s) hereinbefore described and such may be varied in construction and detail without departing from the scope of the patent monopoly hereby sought.

Claims

1. A utility pipe to be laid underground, said pipe being composed of plastics material and having a metallic element extending continuously therealong, the metallic element being traceable by a metal detector when the pipe is buried underground.

2. A utility pipe according to Claim 1 wherein the metallic element is traceable by electrical inductive means.

3. A utility pipe according to Claim 1 or Claim 2, wherein the metallic element extends linearly generally parallel to the axis of the pipe.

4. A utility pipe according to Claim 1 or Claim 2, wherein the metallic element is spiral wound in relation to the pipe axis.

5. A utility pipe according to any preceding Claim, wherein the metallic element comprises a wire bonded to the exterior of the pipe.

6. A utility pipe, other than water pipe, according to any one of Claims 1 to 4, wherein the metallic element comprises a wire bonded to the interior of the pipe.

7. A utility pipe according to any one of Claims 1 to 4, wherein the metallic element is embedded in the plastics material forming the pipe wall.

8. A utility pipe according to any one of Claims 1 to 4, wherein the metallic element comprises a metallic composition extruded with the plastics material so as to form the pipe wall therewith.

9. A utility pipe according to any Claim 8, wherein the metallic composition extends substantially around 360 of the pipe's cross-sectional area.

10. A utility pipe according to any Claim 8, wherein the metallic composition extends for a small arcuate extent, e.g. less than 60", of the pipe's cross-sectional area.

12. A utility pipe substantially as herein described with reference to and/or as illustrated in the accomapnying drawings.