A PIPE ASSEMBLY HAVING TRACEABILITY AND LEAKAGE DETECTION
FEATURES.
Field of Invention:
The present invention relates to a pipe assembly having traceability and leakage detection features and pipes incorporating the same.
Background of Invention:
Various utilities such as Water supply and Sewerage Board, Gas Utilities, Municipal Authorities etc. install plastic pipes and in the case of Water Supply from source to storage to water treatment plant to main reservoir, to houses and village being serviced. In some cases locating wires were laid alongside, spiraled around, or taped to the plastic pipes but in many cases locating wires were not provided. With time plastic pipes become brittle and require replacement. Such pipes are of course buried and connect with the mains well below the surface of the earth. With metal pipes it is quite simple to trace the location of the pipe by means of magnetometer devices or by applying RF signals to the pipe and picking up the radiation from the pipe with a sensing device. With plastic pipes having no locator wire conventional techniques are not applicable. It is common practice to look for markings on curbings and to use 'as-built' drawings for reference. Experience shows that these markings and drawings were not accurate and the workers were forced to dig numerous holes in an attempt to locate the pipe. With the large number of plastic pipes installations the randomness of the dig and locate method appears to be impractical. Also the loose locating wires laid alongside the plastic pipes do not present a sustainable and effective solution for traceability as they tend to get damaged, do not necessarily follow the path of the plastic pipes and may not be in the same trench. US patents 4573829, 6286542 and 5044824 describe methods and means to insert a conducting wire into an existing pipeline so as to detect the location of pipe.
Further, in the event of leakage in the pipe it is essential to determine the exact location of the leak to facilitate replacement. Thus the problem of detecting leaks is two fold. First
the exact location of the pipes is to be determined and then the exact location of the leak on the pipeline is to be determined. Various known methods are available for the detection of leaks in pipes. In one such system a pulse is sent down a transmission line placed in proximity to a pipe being monitored. Reflections of the pulses are monitored and threshold values are established above and below the reflected waveforms. Upon the occurrence of a leak or break in the pipe or a break in the cable the characteristic impedance of the line changes thus resulting in a change in the waveform of the reflection. If the change in impedance is sufficient to cause the waveform to cross either the upper or lower threshold, a leak or break is indicated. By noting the position of the change in shape of the waveforms, the location and other characteristics of the leak may be determined.
Thus, to overcome the aforementioned drawbacks there exists a need for a simple, economical and practical system that can both locate and detect leakage in a non-metallic pipe.
Objective of Invention:
In order to overcome the above limitations the invention provides for a system to be used
for traceability and leakage detection purposes.
The object of the invention is to provide a non-metallic pipe for sub terrain use with
traceability feature.
Another object of the invention is to provide a non-metallic pipe with leakage detection
capability.
Another object of the invention is to provide a seal proof method of joining the tracer
cable of two adjacent non-metallic pipes with no wastage of pipe.
Summary of Invention:
A pipe assembly having traceability and leakage detection features for locating pipes and detecting leakage in the same comprising:
- a non metallic pipe to transport fluids,
a co-extruded tracer cable on said non-metallic pipe to which pulses are applied to locate said non metallic pipe and detect leakage on the same,
- means for joining said co-extruded tracer cable of two adjacent said non
metallic pipes.
whereby said pipes are butt welded together to form a continuous pipeline.
Brief Description of Accompanying Figures:
Figure 1 shows the perspective view of the pipe with co-extruded cable according to the
present invention.
Figure 2 shows the cross section view of the pipe with co-extruded cable according to the
present invention.
Figure 3 shows the top, bottom and side views of the pipes with co-extruded cable
according to the present invention.
Figure 4 shows the system as defined by the instant invention using transmitter and
receiver.
Figure 5 shows the system in accordance with the instant invention to determine leakage
in the pipe.
Figure 6 shows the waveforms as seen on an analyzer device such as an oscilloscope.
Figure 7 shows the method of joining the tracer cables of two adjacent pipes in
accordance with the instant invention.
Detailed Description of accompanying Figures:
Referring to the accompanying drawings, Figure 1 shows the perspective view of the pipe (10) incorporating the instant invention. As seen the pipe has a co-extruded tracer cable on the pipes outer surface. The tracer wire runs along the entire length of the pipe. The solid stripes (30) on the pipe are markings as defined by the Indian Standards Institute.
Figure 2 shows the cross sectional view of the pipe. Co-extruded tracer cable has pinpoint
wire (40) encased in protective insulation (20).
Figure 3 shows the top, bottom and side views of the said pipe in accordance with the
invention.
Figure 4 shows a portion of the piping system wherein the traceability and leak detection system of the instant invention is applied. Pipe (10) in accordance with the instant invention is made of suitable polymer material such as HDPE and has a co-extruded tracer cable (40) along its entire length encased in suitable polymer material (20). In the preferred embodiment the tracer wire is made of high-grade 99.95% pure copper wire of specified thickness to provide the desired conductivity for carrying the tracer and leak detection signal. The exact location of the HDPE pipe with co-extruded tracer wire is carried out with a multiple frequency locator. This equipment broadly consists of a transmitter, to which the tracer wire is connected and a receiver. When the tracer wire is energized a sensing device on the surface can pick up the signals and thus the exact location of the under-ground pipe can be determined.
For the detection of leakage or break on pipe a system in accordance with the instant invention is as shown in figure 5. A pulse generator (42) such as one shown in the figure 5, or any other known signal generator is coupled to the detecting cable (40) by means of a suitable isolation circuit (44). The isolation circuit may be a passive circuit or may be an active switching circuit that directs the pulse from the pulse generator to the cable when the pulse is present and directs any reflected wave from the cable to an analyzing device such as, for example, an oscilloscope (46) as illustrated in the figure. As the pulse propagates down the line, the voltage across the cable will be proportional to the characteristic impedance of the cable. After the pulse has been applied to the cable there will be a signal present at the input of the cable until a reflected waveform is received. If the characteristic impedance of the cable is uniform and is matched to the pulse of the generator there will be no reflected wave received until the pulse propagates along the entire length of the cable and is reflected by the end of the cable that is normally open circuited. However, because the cables generally do not have characteristic impedance

that is perfectly matched to the impedance of the pulse generator reflections will occur when the pulse encounters such irregularities in impedance. The reflected waveform across the input to the cable would be similar to the waveform illustrated in figure 6, which is illustrative of the type of waveform that would be displayed on the oscilloscope (46). The reflected waveforms may be stored in a memory.
Referring now to figure 6 the waveform has essentially horizontal portion 3 and an upwardly (or downwardly) extending portion 2. The essentially horizontal portion 3 is the result of reflection within the cable and is a function of the characteristic impedance along the length of the cable. Thus the amplitude of the reflected waveform will vary as the characteristic impedance of the cable varies. The upwardly extended portion of the waveform 2 is the result of the pulse being reflected from the open circuited end of the cable. If desired, the far end of the cable could be short-circuited thus resulting in a downwardly extending end reflection, or otherwise terminated. A pair of thresholds 4 and 6 bound the horizontal portion 3 of the waveform. The thresholds 4 and 6 are separated from the horizontal portion of the waveform by an amount sufficient to accommodate variations in the amplitude of the horizontal portion 3 of the waveform caused by variations in the characteristic impedance of the cable. Thus, under normal circumstances, in the absence of any breaks or leaks the thresholds 4 and 6 would bind the horizontal portion of the waveform.
In the event of a leak the characteristic impedance of the transmission line will change. In most cases this change is a decrease in characteristic impedance that occurs in the proximity of the leak or break, resulting in a dip in the waveform. If the dip is of sufficient magnitude to cross the threshold value an alarm indicating a leak is sounded and the approximate position of the leak is determined from the position of the dip in the waveform. Similarly in the event of a break in the cable a new end echo resulting from the reflection at the break in the cable occurs. If this end echo is of sufficient magnitude to cross the threshold 4 an alarm is also sounded. Various other known leak detection means may also be used.
In accordance with another embodiment of the instant invention a co-axial cable may be used as the tracer cable. The co-axial is also co-extruded along the entire length of the non-metallic pipe.
Figure 7 shows the method of joining two tracer cables on adjacent pipes. The pipes are laid end-to-end and welded to form a leak proof joint. Tracer cable (40) is peeled of from ends of both the pipes and passed through a heat shrinkage sleeve (60). The cables are then connected to multistrand flexible cable (62) through tubular metal lugs (64) for crimping that cover the joint of the tracer cable (40) and the multistrand flexible cable (62). Heat is then applied to the heat shrinkage sleeve (60) and the whole joining assembly is sealed.
A pipe assembly having traceability and leakage detection features for locating and detecting leakage in said pipe assembly comprising:
- a non metallic pipe (10) to transport fluids,
- a co-extruded tracer cable (40) on said non-metallic pipe to which pulses are
applied to locate said non metallic pipe and detect leakage on the same,
- said co-extruded tracer cable being encased in suitable polymer material (20).
Brief Description of Accompanying Figures:
Figure 1 shows the perspective view of the pipe with co-extruded cable according to the present invention.
Figure 2 shows the cross section view of the pipe with co-extruded cable according to the
present invention.
Figure 3 shows the top, bottom and side views of the pipes with co-extruded cable
according to the present invention.
Figure 4 shows the system as defined by the instant invention using transmitter and
receiver.
Figure 5 shows the system in accordance with the instant invention to determine leakage
in the pipe.
Figure 6 shows the waveforms as seen on an analyzer device such as an oscilloscope.
Figure 7 shows the method of joining the tracer cables of two adjacent pipes in
accordance with the instant invention.
Detailed Description of accompanying Figures:
Referring to the accompanying drawings, Figure 1 shows the perspective view of the pipe (10) incorporating the instant invention. As seen the pipe has a co-extruded tracer cable on the pipes outer surface. The tracer wire runs along the entire length of the pipe. The solid stripes (30) on the pipe are markings as defined by the Bureau of Indian Standards.

We claim:
1. A pipe assembly having traceability and leakage detection features for locating and
detecting leakage in said pipe assembly comprising:
- a non metallic pipe (10) to transport fluids,
- a co-extruded tracer cable (40) on said non-metallic pipe to which pulses are
applied to locate said non metallic pipe and detect leakage on the same,
- said co-extruded tracer cable being encased in suitable polymer material (20).

2. A pipe assembly as claimed in claim 1 wherein said cable is provided with means for
generating and applying pulses.
3. A pipe assembly as claimed in claim 2 wherein said means for generating and
applying pulses to said cable is a pulse generator.
4. A pipe assembly as claimed in claim 1 wherein said cable is provided with means for
receiving reflections of said pulses.
5. A pipe assembly as claimed in claim 4 wherein said means for receiving reflections
of said pulses is an oscilloscope.

6. A pipe assembly as claimed in claim 1 wherein said pipe is made of high-density
polyethylene (HDPE).
7. A pipe assembly as claimed in claim 1 wherein said cable is made of any suitable
metal.
8. A pipe assembly as claimed in claim 1 wherein said means for joining the two tracer
cables of adjacent pipes is a flexible multistrand cable with tubular metal lugs at its
ends for crimping and to insulate the ends of the tracer cable.
9. A method of locating a concealed or underground non metallic pipe as claimed in
claim 1, and detecting a leak thereof, comprising the steps of:

- connecting the co-extruded cable on said non-metallic pipe to a signal
generator,
- passing signal through the said cable by the signal generator,
- sensing the signal on the surface by means of any known sensing device,
thereby locating the pipe,.
- connecting the co-extruded cable on said non-metallic pipe to a pulse
generator,
- passing pulses through the said cable by the pulse generator
- receiving reflections of said pulses from said cable
- analyzing sa jd reflections to determine presence of leak and its position.
10. A pipe assembly having traceability and leakage detection features substantially as
herein described with reference to and as illustrated by the accompanying drawings.
11. A method of locating a concealed or underground non metallic pipe and detecting a
leak thereof substantially as herein described with reference to and as illustrated by
the accompanying drawings