CA1141019A - Method and means of passive detection of leaks in buried pipes - Google Patents
Method and means of passive detection of leaks in buried pipesInfo
- Publication number
- CA1141019A CA1141019A CA000362730A CA362730A CA1141019A CA 1141019 A CA1141019 A CA 1141019A CA 000362730 A CA000362730 A CA 000362730A CA 362730 A CA362730 A CA 362730A CA 1141019 A CA1141019 A CA 1141019A
- Authority
- CA
- Canada
- Prior art keywords
- location
- leak
- acoustic waves
- correlation
- detectors
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 19
- 238000001514 detection method Methods 0.000 title abstract description 7
- 239000012530 fluid Substances 0.000 claims abstract description 22
- 230000000644 propagated effect Effects 0.000 claims 2
- 230000000007 visual effect Effects 0.000 claims 1
- 230000002596 correlated effect Effects 0.000 abstract description 2
- 230000008878 coupling Effects 0.000 description 4
- 238000010168 coupling process Methods 0.000 description 4
- 238000005859 coupling reaction Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000005259 measurement Methods 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000003345 natural gas Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 241000283984 Rodentia Species 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000003628 erosive effect Effects 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 235000019645 odor Nutrition 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000005654 stationary process Effects 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
- G01M3/24—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using infrasonic, sonic, or ultrasonic vibrations
- G01M3/243—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using infrasonic, sonic, or ultrasonic vibrations for pipes
Abstract
ABSTRACT OF THE DISCLOSURE
A method and means for passive detection of a leak in a buried pipe containing fluid under pressure includes a plurality of acoustic detectors that are placed in con-tact with the pipe. Noise produced by the leak is detected by the detectors, and the detected signals are correlated to locate the leak. In one embodiment of the invention two detectors are placed at different locations to locate a leak between them. In an alternate embodiment two detectors of different waves are placed at substan-tially the same location to determine the distance of the leak from the location.
A method and means for passive detection of a leak in a buried pipe containing fluid under pressure includes a plurality of acoustic detectors that are placed in con-tact with the pipe. Noise produced by the leak is detected by the detectors, and the detected signals are correlated to locate the leak. In one embodiment of the invention two detectors are placed at different locations to locate a leak between them. In an alternate embodiment two detectors of different waves are placed at substan-tially the same location to determine the distance of the leak from the location.
Description
~ ``i METHOD AND MEANS OF PASSIVE
D~TECTION OF I.EAT~S IN BURIED PIP~:S
BAC~iGROUl~D OF l'~JE I~VE~ITIO~
This invention relates to the detection of leaks in ~ipes. In particular, this invention is a method and means of detecting the location of a leak in a buried pipe containing a fluid by analysis of the acoustical signals produce~ in the pipe or the fluid b~ the leak.
When fluids under pressure are contained or carried in-buried pipes, a small local failure of the pipe causes t~o problems. One problem is to detect the fact that there is a leak; the other is to locate the leak to fix ; it. As a general rule, it may be stated that the smaller the leak, the more difficult it is to detect the presence - of the leak and the more difficult it is to locate such a - leak even if its presence is known. In some systems of ~tater pipes a principal method of leak detection involves notlcing the collapse of ground over a buried water pipe as a result of subsurface erosion from a leak.
Such a method of detection is obviously undèsirable in the case of expensive fluids that are carried in the ~i~es or of fluids that are corrosive or flaMmable. For many years natural gas has been doped with chemicals having strong odors to assist in the location of leaks.
Such a rnethod of leak detection, however, is of most use in the absence of pavement over the pipe. Pipe that is buried under concrete or other paving and that carries a corrosive or flamrnable substance presents a challenye that is not met by any of the detection systems just described.
Various types of active acoustic systems serve to detect leaks by exciting acoustic waves in the pipe or in the fluid conveyed in the pipe~ Acoustic detectors are placed to detect signals produced by the discontinuities at the leak, either by responding to reflections generated by the discontinuity or by detectiny differences produced in transmitted siynals by the discontinuity in the pipe.
Such systems, however, generally require substantial breaks in the pipes to generate signals that are large enough to be detected in the presence of the exciting siynals.
It is an object of the present invention to provide a better method and means of detecting leaks in buried pipes.
It is a further object of the present invention to provide a method and means of locating leaks in buried pipes.
It i5 a further object of the present invention to provide a method and means of detecting leaks in pipes carrying fluids under pressure.
Other objects will become apparent in the course of a detailed description of the invention.
SUMMRRY OF T~E INVENTION
Leaks in buried pipes carr~ing or containing fluids are detected by a passive system that responds to acoustic siynals generated by the leak. In one embodiment of the invention a detector of longitudinal or torsional acoustic signals is placed at a first location and a second detector of lonyitudinal or torsional acoustic signals is placed at a location on the other side of the leak.
A radio broadcasting s~stem is used to couple the signals detected by the two detectors to a single location for application to an apparatus for measuring the correlation between the two signals. The cross-correloyra~ of the two signals provides a measure of the distance of the leak from each of the two measuring points and hence of the location of the leak. In a second embodiment a detector of longitudinal acoustic signals and a detector of transverse acoustic signals are placed at the same location. A combination of the cross-correloyram of the two signals with the known differences in the velocity of propagation of longitudinal and transverse siynals provides a measure of the distance of the leak from the measuring point. Signals may propagate either in the fluid or in the pipe.
~RIEF DESCRIPTION OF T~IE DRAWING~
Fig. 1 is a block diagram of an apparatus for the practice of the invention on a buried pipe having a leak.
Fig. 2 is a top view of a coated pipe showing the placement of detectors for the practice of the present invention.
Fig. 3 is a side view of the pipe of Fig. 2 showing placement of the detectors.
Fig. 4 is a block diagram showing the placement of detectors at a single location for the practice of an alternate embodiment of the invention.
Fig. 5 is a plot of an observed correlation coeffi-cient as a function of time delay.
Fiy. 6 is an expanded view of a portion of the plot of Fig. 5.
DETAILED DESCRIPTIO~I OF THE I~VENTIO~I
Fiy. 1 is a block diagram of an apparatus for the ; - ~
practice of the present invention. In Fis. 1 a leak 10 in a buried pipe 12 is located at a distance from a manhole 14 and a borehole 16 that has been sunk from the surface 18 to the pipe 12 to provide a measuring point.
The manhole 14 and borehole 16 have been shown for illus-tration. It is evident that what is important is access to the pipe 12. If manholes were located conveniently then two manholes could be used or in the absence of con-veniently located r,1anholes it might be necessary to use two boreholes.
A transducer 20 is connected and coupled acoustically to pipe 12 in manhole 14 and another transducer 22 is connected to pipe 12 and coupled acoustically to it in borehole 16. The transducers 20 and 22 may be coupled to torsional waves or to lonsitudinal waves in the pipe 12.
While the preferred mode of operation is to couple both transducers 20 and 22 to the same form of wave, it is also possible to couple one of the transducers 20 and 22 to a lonyitudinal wave and the other to a torsional wave.
The form of the coupling is a matter of choice for the operator and will normally be made so as to detect the strongest signal.
The invention works because leaks generate noise in the pipe, the fluid or both. The term "noise" is here taken to refer to a signal that is substantially random in time although not necessarily completely random. Such a signal is describable by its spectrum. Two detected signals that are yenerated by the same leak will exhibit a cross-correlogram that can be interpreted to locate the leak. The cross-correlation is determined by the circuit of Fig. 1 in which the measuring equipment 24 1~4~ 9 is lGcated near manhole 14. An acoustical signal that is detected by transducer 22 is there converted to an electrical signal that is amplified in preamplifier 26 and is amplified again as desired in a variable post-amplifier 2~. ~he amplified siynal froM post-amplifier 28 is coupled to a radio trans~itter 30 that must be capable of broadcasting a signal with a bandwidth of 7 kEIz through a trans~itting antenna 31 to a receiving antenna 32, thence to a receiver 33. The signal received by receiver 33 is applied to a bandpass filter 34 that passes frequencies in the range of 3 to 4 kHz. ~he out-put of bandpass filter 34 is connected to hishpass filter 36 which passes fre~uencies above 150 Hz. At the same time transducer 20 receives a signal in manhole 14 and generates an electrical signal that is coupled to preamplifier 38. The output of preamplifier 38 is connected to bandpass filter 40 which passes fre-quencies in the range of 3 to 4 k~lz. The output of band-pass filter is amplified as necessary in variable post-amplifier 42, anZ the amplified signal from post-amplifier 42 is applied to highpass filter 44 which passes frequencies above 150 ~z. The output signals from highpass filters 36 and 44 are applied to cross-correlator 46 to generate a cross-correlogram that is made visible on display device 48. The cross-correlogram of two signals is defined as a plot of the cross-correlation coefficient of the two signals as a function of the time delay between the signals. ~nowledge of the distance between ~anhole 14 and borehole 16 and of the velocity of propagation of the wave detected by each of of the tranducers 20 and 22 provides information sufficient to interpret the correloyram displayed on dis-play device 48 to locate the leak 10.
Figs. 2 and 3 are views of a coated pipe showing the placement of detectors for the practice of the present invention. Fis. 2 is a top view and Fig. 3 is a side view of the same pipe. In Figs. 2 and 3, pipe 12 is a carrier of a liquid such as fuel oil or a gas such as natural gas, or it may be an electrical conduit that includes a power line and an insulating fluid under pressure. When such a pipe 12 is buried underground, it is desirable to protect the outer surface by some means such as tar coating 54. When it is desired to detect or locate leaks in pipe 12, it is necessary to gain access to - pipe 12 to remove tar to expose the surface 56 which is typically of steel. A coupling block 58 is placed against surface 56 in acoustical contact with surface 56 and an accelerometer is connected to coupling block 58 to convert acoustical signals into electrical signals. In Figs. 2 and 3, accelerometer 60 is connected to coupling block 58 in such a way as to detect lon~itudinal acoustical waves in pipe 12 and accelerometer 62 is connected to respond to torsional acoustic waves in pipe 12. Reasons for the selection of longitudinal or torsional waves will become apparent in the description of the invention. It should be noted that the accelerometers 60 and 62 of Figs. 2 and 3 could both be placed to respond either to lon~i-tudinal or torsional waves and that when they are placed on opposite sides of a suspected leak as shown in ~ig. 1 it would normally be simpler to orient each of the accelerometers 60 and 62 of Figs. 2 and 3 to respond to the same type of acoustical signal. This simplifies calculations in that the velocities of longitudinal ar.d torsional signals are typically different, thus requiring an additional step of data processing if the arrangement of Figs. 2 and 3 is used to make an actual measurement.
Fig. 4 is a block diagram of an alternate embodiment of the invention. In Fiy. 4 a leak 70 produces noise in the fluid in a pipe 72. A longitudinal-wave tranducer 74 and a torsional-wave tranducer 76 are located together on the pipe 72 with access through a single manhole or bore-hole. The signal from longitudinal-wave transducer 74 is amplified in prea~plifier 7~, filtered in bandpass filter ~0 and fed to variable post-amplifier 82. The amplified signal from post-amplifier 82 is applied through highpass filter 84 to correlator 85. The output of tor-sional-wave tranducer 76 is amplified ih preamplifier &6 and applied to bandpass filter e8. The output of band-pass filter ~8 is connected through variable post-amplifier 89 to highpass filter 90, thence to correlator ~5.
5tatistical correlation between the two signals is made visible on disp~ay device 92 in which a knowledge of the differences in the velocity of propa~ation of longitudinal waves and torsional waves in the fluid provides a measure of the distance of the leak from the measuring point.
Figs. 5 and 6 illustrate a cross-correlation co-efficient obtained on a test pipe with a known leak. The pipe was carbon steel, type A3, Schedule 40, 207 feet in length and 8 inches in internal diameter. It contained a length of hiyh-voltage transmission cable and was filled with insulatiny oil ~aintained at a pressure of the order of 125 psi. A hole having a diameter of 0.035 inches was drilled in the pipe and was allowed to leak into sand to produce the acoustical waves that were detected to produce the correlation plots of Figs. 5 and 6. The hole was located approximately midway between two sensors of longitudinal waves. The correlogram of Fig. 5 is included for completeness to show the repeated locations of correlations that result from the interaction of reflected waves. The envelope of the set of high peaks near the center of Fig. 5 represents the correlation between signal~ received directly front the leak to each of the two sensors. The envelope of the next peaks going outward in either direction from the center represent correlations from signals that are reflected from the end caps used to terr;linate the test section of pipe. These signals are an artifact of the test setup and have been removed in Fig. 6 which is a plot of the center reqion of Fig. 5, expanded in scale to illustrate better the correlation of the direct signals received by each of the two sensors. It can be seen from Fi~. 6 that the peak of the envelope of the correlation is displaced by 0.4~
milliseconds from the center of the correlation plot.
This displacement in time difference when multiplied by the known velocity of propagation of longitudinal acoustic waves in the fluid indicates that the leak is located a distance of four feet from the center of the pipe in the direction of the transducer that is connected to the cross-correlator as the neyative input.
The calculation is performed as follows for the embodiment of Fis. 1:
With a aistance ~ between sensors A and a, denote by X the distance from sensor A to the leak.
Sensor B is then a distance ( ~- X) from the leak. The propa~ation time of a signal from the leak to sensor A is ~A = X/c, where c is the acoustic velocity of the wave that is detected, either longitudinal or torsional. The propa-gation time from the leak to sensor B is~ = (~- X)/c.
The time difference (r -~B) = (~/c) - [ ~- X)/c] = 2X - ~.
Solvins, X = (~A-~ c + ~, and the distance of the leak from the midpoint is ( ~A - rB)C, measured in the direction of the A sensor. Since the first peak of the correlation coefficient occurs at a time difference of (~ -/B), it is necessary only to know the distance ~ and the acoustic velocity c to locate the leak from the correloyram. The distance ~ is available to a utility from maps of its system; failing that, it may be measured.
Acoustic velocity c will normally be measured by obtaining the correlogram of a signal applied at one sensor with that detected at another. The time delay of the peak, when divided into the distance between sensors, is the acoustic velocity c.
A comparable calculation is performed for the embodiment of Fig. 4, where sensors A and B are together and the acoustic velocities differ. In this case, it is necessary to know the respective acoustic velocities, here denoted cA and CB. Calling x the distance from the sensors to the leak, it follows that X = CA~A = CB~--B ' where JA and ~B are the respective propagation times of the A and B waves. Hence /~ = x /CA and ~BS x/CB, and their difference (r A - rB) = x (l/CA _ 1/CB).
The difference ( ~A- ~ ) is determinable from the correlogralil, so that _ 9 _ 1~ 9 x (/ A(C ~ Cg) ~ he cross-correlation between two time-varying voltages Vl(t) and ~2(t) is a measure of the similarity of their statistics. In partlcular, if the two voltages represent random processes whose statistics do not change in time, then each is said to be stationary. For station-ary processes the correlation is well known to be a function only of the time delay in measurement for the case o~ autocorrelation and to be a function of the time delay in measuring the cross-correlation between two signals. The cross-correlation which is determined as a measure of the location of the leak in the present inven-tion is obtained by applyin~ an appropriately band-limited signal from each of the detectors to a multiplier after applying a variable delay to one of the signals. The product of one of the signals with the delayed second siynal is inteyrated with respect to time tc produce a correlation signal that is a function of time delay. In the practice of the present invention, it has been con-venient either to make cross~correlations of signals of the same kind (both longitudinal or both torsional) at two different locations or to make cross-correlations of different kinds of si~nals (one longitudinal and one torsional) at essentially the same location~ Mote that if different signals are detected at a sinyle location it will be necessary to find out in which direction the leak is, either by measuring at another manhole or by separatiny the detectors by several feet at the single location.
Either of these methods produces a correlated output that is substantially stationary over the typical period required to make measurements, which is of the order of 15 minutes. The time may vary depending on the ratio of signal to noise and the degree of certainty required by ; the operator. In general, as the measuriny time becomes lGnger, the peaks in the correlogram become more distinct.
The correlations of Figs. 5 and 6 were recorded with a 15-minute averaging time. Other leaks producing larger acoustical signals can be expected to provide adequate correlation to permit their location in less than 15 minutes. The power of the correlation technique lies in the fact that a leak-signal may ~e buried in noise, yet the location of the leak may be obtained with excellent results. In Figs. 5 and 6 the leak-signal output from the amplifiers was mixed with a random noise signal so that the leak-signal power and the noise-signal power were equal and therefore only marginally detectable with a passive acoustic device which measures signal power. The correlogram shown in Fig. 5 has a 48-dB
signal-to-noise ratio. Thus a large sain in the signal-to-noise ratio is achieved through the correlation technique. This allows one to locate leaks that were previously undetectable.
D~TECTION OF I.EAT~S IN BURIED PIP~:S
BAC~iGROUl~D OF l'~JE I~VE~ITIO~
This invention relates to the detection of leaks in ~ipes. In particular, this invention is a method and means of detecting the location of a leak in a buried pipe containing a fluid by analysis of the acoustical signals produce~ in the pipe or the fluid b~ the leak.
When fluids under pressure are contained or carried in-buried pipes, a small local failure of the pipe causes t~o problems. One problem is to detect the fact that there is a leak; the other is to locate the leak to fix ; it. As a general rule, it may be stated that the smaller the leak, the more difficult it is to detect the presence - of the leak and the more difficult it is to locate such a - leak even if its presence is known. In some systems of ~tater pipes a principal method of leak detection involves notlcing the collapse of ground over a buried water pipe as a result of subsurface erosion from a leak.
Such a method of detection is obviously undèsirable in the case of expensive fluids that are carried in the ~i~es or of fluids that are corrosive or flaMmable. For many years natural gas has been doped with chemicals having strong odors to assist in the location of leaks.
Such a rnethod of leak detection, however, is of most use in the absence of pavement over the pipe. Pipe that is buried under concrete or other paving and that carries a corrosive or flamrnable substance presents a challenye that is not met by any of the detection systems just described.
Various types of active acoustic systems serve to detect leaks by exciting acoustic waves in the pipe or in the fluid conveyed in the pipe~ Acoustic detectors are placed to detect signals produced by the discontinuities at the leak, either by responding to reflections generated by the discontinuity or by detectiny differences produced in transmitted siynals by the discontinuity in the pipe.
Such systems, however, generally require substantial breaks in the pipes to generate signals that are large enough to be detected in the presence of the exciting siynals.
It is an object of the present invention to provide a better method and means of detecting leaks in buried pipes.
It is a further object of the present invention to provide a method and means of locating leaks in buried pipes.
It i5 a further object of the present invention to provide a method and means of detecting leaks in pipes carrying fluids under pressure.
Other objects will become apparent in the course of a detailed description of the invention.
SUMMRRY OF T~E INVENTION
Leaks in buried pipes carr~ing or containing fluids are detected by a passive system that responds to acoustic siynals generated by the leak. In one embodiment of the invention a detector of longitudinal or torsional acoustic signals is placed at a first location and a second detector of lonyitudinal or torsional acoustic signals is placed at a location on the other side of the leak.
A radio broadcasting s~stem is used to couple the signals detected by the two detectors to a single location for application to an apparatus for measuring the correlation between the two signals. The cross-correloyra~ of the two signals provides a measure of the distance of the leak from each of the two measuring points and hence of the location of the leak. In a second embodiment a detector of longitudinal acoustic signals and a detector of transverse acoustic signals are placed at the same location. A combination of the cross-correloyram of the two signals with the known differences in the velocity of propagation of longitudinal and transverse siynals provides a measure of the distance of the leak from the measuring point. Signals may propagate either in the fluid or in the pipe.
~RIEF DESCRIPTION OF T~IE DRAWING~
Fig. 1 is a block diagram of an apparatus for the practice of the invention on a buried pipe having a leak.
Fig. 2 is a top view of a coated pipe showing the placement of detectors for the practice of the present invention.
Fig. 3 is a side view of the pipe of Fig. 2 showing placement of the detectors.
Fig. 4 is a block diagram showing the placement of detectors at a single location for the practice of an alternate embodiment of the invention.
Fig. 5 is a plot of an observed correlation coeffi-cient as a function of time delay.
Fiy. 6 is an expanded view of a portion of the plot of Fig. 5.
DETAILED DESCRIPTIO~I OF THE I~VENTIO~I
Fiy. 1 is a block diagram of an apparatus for the ; - ~
practice of the present invention. In Fis. 1 a leak 10 in a buried pipe 12 is located at a distance from a manhole 14 and a borehole 16 that has been sunk from the surface 18 to the pipe 12 to provide a measuring point.
The manhole 14 and borehole 16 have been shown for illus-tration. It is evident that what is important is access to the pipe 12. If manholes were located conveniently then two manholes could be used or in the absence of con-veniently located r,1anholes it might be necessary to use two boreholes.
A transducer 20 is connected and coupled acoustically to pipe 12 in manhole 14 and another transducer 22 is connected to pipe 12 and coupled acoustically to it in borehole 16. The transducers 20 and 22 may be coupled to torsional waves or to lonsitudinal waves in the pipe 12.
While the preferred mode of operation is to couple both transducers 20 and 22 to the same form of wave, it is also possible to couple one of the transducers 20 and 22 to a lonyitudinal wave and the other to a torsional wave.
The form of the coupling is a matter of choice for the operator and will normally be made so as to detect the strongest signal.
The invention works because leaks generate noise in the pipe, the fluid or both. The term "noise" is here taken to refer to a signal that is substantially random in time although not necessarily completely random. Such a signal is describable by its spectrum. Two detected signals that are yenerated by the same leak will exhibit a cross-correlogram that can be interpreted to locate the leak. The cross-correlation is determined by the circuit of Fig. 1 in which the measuring equipment 24 1~4~ 9 is lGcated near manhole 14. An acoustical signal that is detected by transducer 22 is there converted to an electrical signal that is amplified in preamplifier 26 and is amplified again as desired in a variable post-amplifier 2~. ~he amplified siynal froM post-amplifier 28 is coupled to a radio trans~itter 30 that must be capable of broadcasting a signal with a bandwidth of 7 kEIz through a trans~itting antenna 31 to a receiving antenna 32, thence to a receiver 33. The signal received by receiver 33 is applied to a bandpass filter 34 that passes frequencies in the range of 3 to 4 kHz. ~he out-put of bandpass filter 34 is connected to hishpass filter 36 which passes fre~uencies above 150 Hz. At the same time transducer 20 receives a signal in manhole 14 and generates an electrical signal that is coupled to preamplifier 38. The output of preamplifier 38 is connected to bandpass filter 40 which passes fre-quencies in the range of 3 to 4 k~lz. The output of band-pass filter is amplified as necessary in variable post-amplifier 42, anZ the amplified signal from post-amplifier 42 is applied to highpass filter 44 which passes frequencies above 150 ~z. The output signals from highpass filters 36 and 44 are applied to cross-correlator 46 to generate a cross-correlogram that is made visible on display device 48. The cross-correlogram of two signals is defined as a plot of the cross-correlation coefficient of the two signals as a function of the time delay between the signals. ~nowledge of the distance between ~anhole 14 and borehole 16 and of the velocity of propagation of the wave detected by each of of the tranducers 20 and 22 provides information sufficient to interpret the correloyram displayed on dis-play device 48 to locate the leak 10.
Figs. 2 and 3 are views of a coated pipe showing the placement of detectors for the practice of the present invention. Fis. 2 is a top view and Fig. 3 is a side view of the same pipe. In Figs. 2 and 3, pipe 12 is a carrier of a liquid such as fuel oil or a gas such as natural gas, or it may be an electrical conduit that includes a power line and an insulating fluid under pressure. When such a pipe 12 is buried underground, it is desirable to protect the outer surface by some means such as tar coating 54. When it is desired to detect or locate leaks in pipe 12, it is necessary to gain access to - pipe 12 to remove tar to expose the surface 56 which is typically of steel. A coupling block 58 is placed against surface 56 in acoustical contact with surface 56 and an accelerometer is connected to coupling block 58 to convert acoustical signals into electrical signals. In Figs. 2 and 3, accelerometer 60 is connected to coupling block 58 in such a way as to detect lon~itudinal acoustical waves in pipe 12 and accelerometer 62 is connected to respond to torsional acoustic waves in pipe 12. Reasons for the selection of longitudinal or torsional waves will become apparent in the description of the invention. It should be noted that the accelerometers 60 and 62 of Figs. 2 and 3 could both be placed to respond either to lon~i-tudinal or torsional waves and that when they are placed on opposite sides of a suspected leak as shown in ~ig. 1 it would normally be simpler to orient each of the accelerometers 60 and 62 of Figs. 2 and 3 to respond to the same type of acoustical signal. This simplifies calculations in that the velocities of longitudinal ar.d torsional signals are typically different, thus requiring an additional step of data processing if the arrangement of Figs. 2 and 3 is used to make an actual measurement.
Fig. 4 is a block diagram of an alternate embodiment of the invention. In Fiy. 4 a leak 70 produces noise in the fluid in a pipe 72. A longitudinal-wave tranducer 74 and a torsional-wave tranducer 76 are located together on the pipe 72 with access through a single manhole or bore-hole. The signal from longitudinal-wave transducer 74 is amplified in prea~plifier 7~, filtered in bandpass filter ~0 and fed to variable post-amplifier 82. The amplified signal from post-amplifier 82 is applied through highpass filter 84 to correlator 85. The output of tor-sional-wave tranducer 76 is amplified ih preamplifier &6 and applied to bandpass filter e8. The output of band-pass filter ~8 is connected through variable post-amplifier 89 to highpass filter 90, thence to correlator ~5.
5tatistical correlation between the two signals is made visible on disp~ay device 92 in which a knowledge of the differences in the velocity of propa~ation of longitudinal waves and torsional waves in the fluid provides a measure of the distance of the leak from the measuring point.
Figs. 5 and 6 illustrate a cross-correlation co-efficient obtained on a test pipe with a known leak. The pipe was carbon steel, type A3, Schedule 40, 207 feet in length and 8 inches in internal diameter. It contained a length of hiyh-voltage transmission cable and was filled with insulatiny oil ~aintained at a pressure of the order of 125 psi. A hole having a diameter of 0.035 inches was drilled in the pipe and was allowed to leak into sand to produce the acoustical waves that were detected to produce the correlation plots of Figs. 5 and 6. The hole was located approximately midway between two sensors of longitudinal waves. The correlogram of Fig. 5 is included for completeness to show the repeated locations of correlations that result from the interaction of reflected waves. The envelope of the set of high peaks near the center of Fig. 5 represents the correlation between signal~ received directly front the leak to each of the two sensors. The envelope of the next peaks going outward in either direction from the center represent correlations from signals that are reflected from the end caps used to terr;linate the test section of pipe. These signals are an artifact of the test setup and have been removed in Fig. 6 which is a plot of the center reqion of Fig. 5, expanded in scale to illustrate better the correlation of the direct signals received by each of the two sensors. It can be seen from Fi~. 6 that the peak of the envelope of the correlation is displaced by 0.4~
milliseconds from the center of the correlation plot.
This displacement in time difference when multiplied by the known velocity of propagation of longitudinal acoustic waves in the fluid indicates that the leak is located a distance of four feet from the center of the pipe in the direction of the transducer that is connected to the cross-correlator as the neyative input.
The calculation is performed as follows for the embodiment of Fis. 1:
With a aistance ~ between sensors A and a, denote by X the distance from sensor A to the leak.
Sensor B is then a distance ( ~- X) from the leak. The propa~ation time of a signal from the leak to sensor A is ~A = X/c, where c is the acoustic velocity of the wave that is detected, either longitudinal or torsional. The propa-gation time from the leak to sensor B is~ = (~- X)/c.
The time difference (r -~B) = (~/c) - [ ~- X)/c] = 2X - ~.
Solvins, X = (~A-~ c + ~, and the distance of the leak from the midpoint is ( ~A - rB)C, measured in the direction of the A sensor. Since the first peak of the correlation coefficient occurs at a time difference of (~ -/B), it is necessary only to know the distance ~ and the acoustic velocity c to locate the leak from the correloyram. The distance ~ is available to a utility from maps of its system; failing that, it may be measured.
Acoustic velocity c will normally be measured by obtaining the correlogram of a signal applied at one sensor with that detected at another. The time delay of the peak, when divided into the distance between sensors, is the acoustic velocity c.
A comparable calculation is performed for the embodiment of Fig. 4, where sensors A and B are together and the acoustic velocities differ. In this case, it is necessary to know the respective acoustic velocities, here denoted cA and CB. Calling x the distance from the sensors to the leak, it follows that X = CA~A = CB~--B ' where JA and ~B are the respective propagation times of the A and B waves. Hence /~ = x /CA and ~BS x/CB, and their difference (r A - rB) = x (l/CA _ 1/CB).
The difference ( ~A- ~ ) is determinable from the correlogralil, so that _ 9 _ 1~ 9 x (/ A(C ~ Cg) ~ he cross-correlation between two time-varying voltages Vl(t) and ~2(t) is a measure of the similarity of their statistics. In partlcular, if the two voltages represent random processes whose statistics do not change in time, then each is said to be stationary. For station-ary processes the correlation is well known to be a function only of the time delay in measurement for the case o~ autocorrelation and to be a function of the time delay in measuring the cross-correlation between two signals. The cross-correlation which is determined as a measure of the location of the leak in the present inven-tion is obtained by applyin~ an appropriately band-limited signal from each of the detectors to a multiplier after applying a variable delay to one of the signals. The product of one of the signals with the delayed second siynal is inteyrated with respect to time tc produce a correlation signal that is a function of time delay. In the practice of the present invention, it has been con-venient either to make cross~correlations of signals of the same kind (both longitudinal or both torsional) at two different locations or to make cross-correlations of different kinds of si~nals (one longitudinal and one torsional) at essentially the same location~ Mote that if different signals are detected at a sinyle location it will be necessary to find out in which direction the leak is, either by measuring at another manhole or by separatiny the detectors by several feet at the single location.
Either of these methods produces a correlated output that is substantially stationary over the typical period required to make measurements, which is of the order of 15 minutes. The time may vary depending on the ratio of signal to noise and the degree of certainty required by ; the operator. In general, as the measuriny time becomes lGnger, the peaks in the correlogram become more distinct.
The correlations of Figs. 5 and 6 were recorded with a 15-minute averaging time. Other leaks producing larger acoustical signals can be expected to provide adequate correlation to permit their location in less than 15 minutes. The power of the correlation technique lies in the fact that a leak-signal may ~e buried in noise, yet the location of the leak may be obtained with excellent results. In Figs. 5 and 6 the leak-signal output from the amplifiers was mixed with a random noise signal so that the leak-signal power and the noise-signal power were equal and therefore only marginally detectable with a passive acoustic device which measures signal power. The correlogram shown in Fig. 5 has a 48-dB
signal-to-noise ratio. Thus a large sain in the signal-to-noise ratio is achieved through the correlation technique. This allows one to locate leaks that were previously undetectable.
Claims (9)
1. A method of detecting the location of a leak in a buried pipe that contains a fluid, the method compris-ing the steps of:
detecting acoustic waves of a first particular type produced by the leak and propagated to a first location;
detecting acoustic waves of a second particular type produced by the leak and propagated to a second location;
transmitting the detected acoustic waves from the second location to the first location; and determining a cross-correlation between the detected acoustic waves from the first location and the detected acoustic waves from the second location;
which cross-correlation is a measure of the location of the leak with respect to the first and second locations.
detecting acoustic waves of a first particular type produced by the leak and propagated to a first location;
detecting acoustic waves of a second particular type produced by the leak and propagated to a second location;
transmitting the detected acoustic waves from the second location to the first location; and determining a cross-correlation between the detected acoustic waves from the first location and the detected acoustic waves from the second location;
which cross-correlation is a measure of the location of the leak with respect to the first and second locations.
2. The method of claim 1 wherein the first and second particular types of acoustic waves are longitud-inal acoustic waves.
3. The method of claim 1 wherein the first and second particular types of acoustic waves are torsional acoustic waves.
4. A method of detecting the location of a leak in a buried pipe that contains a fluid, the method compris-ing the steps of:
detecting longitudinal acoustic waves at a measuring location;
detecting torsional acoustic waves at the measuring location; and determining a cross-correlation between the detected longitudinal acoustic waves and the detected torsional acoustic waves, which cross-correlation provides a measure of the location of the leak with respect to the measuring location.
detecting longitudinal acoustic waves at a measuring location;
detecting torsional acoustic waves at the measuring location; and determining a cross-correlation between the detected longitudinal acoustic waves and the detected torsional acoustic waves, which cross-correlation provides a measure of the location of the leak with respect to the measuring location.
5. An apparatus for detecting a location of a leak in a buried pipe containing a fluid through the use of acoustical signals produced in the fluid by the escape of fluid at the leak, the apparatus comprising:
a first detector of acoustic waves disposed in acoustical contact with the pipe at a first location;
a second detector of acoustic waves disposed in acoustical contact with the pipe at a second location;
means connected to the second detector for communicating a signal detected by the second detector to the first location; and means responsive to a signal from the first detector and to the communicated signal from the second detector for measuring cross-correlation between the signals, which cross-correlation is interpretable to indicate the distance of the leak from the first and second locations.
a first detector of acoustic waves disposed in acoustical contact with the pipe at a first location;
a second detector of acoustic waves disposed in acoustical contact with the pipe at a second location;
means connected to the second detector for communicating a signal detected by the second detector to the first location; and means responsive to a signal from the first detector and to the communicated signal from the second detector for measuring cross-correlation between the signals, which cross-correlation is interpretable to indicate the distance of the leak from the first and second locations.
6. The apparatus of claim 5 wherein the first and second detectors are detectors of longitudinal acoustic waves.
7. The apparatus of claim 5 wherein the first and second detectors are detectors of torsional acoustic waves.
8. The apparatus of claim 5 wherein the means for measuring cross-correlation comprise an electronic cross-correlator having a visual display.
9. An apparatus for detecting a location of a leak in a buried pipe through the use of acoustical signals produced in the fluid by the escape of fluid at the leak, the apparatus comprising:
a detector of longitudinal acoustic waves disposed at a measuring location;
a detector of torsional acoustic waves disposed at the measuring location; and means connected to the detectors of longitudinal and torsional acoustic signals for obtaining a correlogram of signals detected by the detectors, which correlogram provides a measure of distance from the measuring location to the leak.
a detector of longitudinal acoustic waves disposed at a measuring location;
a detector of torsional acoustic waves disposed at the measuring location; and means connected to the detectors of longitudinal and torsional acoustic signals for obtaining a correlogram of signals detected by the detectors, which correlogram provides a measure of distance from the measuring location to the leak.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/089,346 US4289019A (en) | 1979-10-30 | 1979-10-30 | Method and means of passive detection of leaks in buried pipes |
| US089,346 | 1979-10-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1141019A true CA1141019A (en) | 1983-02-08 |
Family
ID=22217163
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000362730A Expired CA1141019A (en) | 1979-10-30 | 1980-10-20 | Method and means of passive detection of leaks in buried pipes |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4289019A (en) |
| JP (1) | JPS5673331A (en) |
| CA (1) | CA1141019A (en) |
| DE (1) | DE3040932A1 (en) |
| FR (1) | FR2468898A1 (en) |
| GB (1) | GB2062864B (en) |
Families Citing this family (81)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU941776A1 (en) * | 1979-03-13 | 1982-07-07 | Проектный Институт "Коммуналпроект" Министерства Коммунального Хозяйства Эстонской Сср | Device for automatic location of pipeline damages |
| US4327576A (en) * | 1980-05-05 | 1982-05-04 | The United States Of America As Represented By The Secretary Of The Navy | Acoustic leak detector |
| US4747309A (en) * | 1980-10-02 | 1988-05-31 | Imperial Chemical Industries Plc | Structures and methods of testing them with linear microphones |
| FR2495773A1 (en) * | 1980-12-04 | 1982-06-11 | Petroles Cie Francaise | MARINE PLATFORM PROVIDED WITH MEANS FOR DETECTION OF POSSIBLE CRACKS |
| DE3204874C2 (en) * | 1982-02-11 | 1994-07-14 | Atlas Elektronik Gmbh | Passive method for obtaining target data from a sound source |
| JPS58144710A (en) * | 1982-02-23 | 1983-08-29 | Honda Motor Co Ltd | Running path guiding device for vehicle |
| JPS58168934A (en) * | 1982-03-31 | 1983-10-05 | Hitachi Ltd | Method and device for detecting leakage of liquid |
| GB8303324D0 (en) * | 1983-02-07 | 1983-03-09 | Secr Defence | Control systems |
| US4480473A (en) * | 1983-05-26 | 1984-11-06 | General Motors Corporation | Acoustic inspection method |
| DE3336245A1 (en) * | 1983-10-05 | 1985-04-25 | Kraftwerk Union AG, 4330 Mülheim | METHOD FOR DETERMINING A LEAK AT PRESSURE-CONTAINING CONTAINERS AND DEVICE THEREFOR |
| US4571994A (en) * | 1984-08-06 | 1986-02-25 | The United States Of America As Represented By The Secretary Of The Navy | Acoustical testing of hydraulic actuators |
| GB2176604B (en) * | 1985-06-06 | 1989-07-26 | Stc Plc | Detecting gas leaks |
| FR2600163B1 (en) * | 1986-06-16 | 1989-12-22 | Metravib Sa | METHOD AND DEVICE FOR DETECTING AND LOCATING LEAKS IN A PIPELINE CONDUCTED BY A FLUID |
| JPS62297741A (en) * | 1986-06-17 | 1987-12-24 | Kensaku Imaichi | Detecting method for leaking place of conduit system fluid |
| FR2626974B1 (en) * | 1988-02-09 | 1990-12-07 | Eaux Cie Gle | METHOD AND DEVICE FOR DETECTING LEAKS ON FLUID PIPES |
| US4970467A (en) * | 1989-04-27 | 1990-11-13 | Burnett Gale D | Apparatus and method for pulse propagation analysis of a pipeline or the like |
| US4965774A (en) * | 1989-07-26 | 1990-10-23 | Atlantic Richfield Company | Method and system for vertical seismic profiling by measuring drilling vibrations |
| US5038614A (en) * | 1989-08-10 | 1991-08-13 | Atlantic Richfield Company | Acoustic vibration detection of fluid leakage from conduits |
| US5058419A (en) * | 1990-04-10 | 1991-10-22 | Earl H. Ruble | Method and apparatus for determining the location of a sound source |
| US5272646A (en) * | 1991-04-11 | 1993-12-21 | Farmer Edward J | Method for locating leaks in a fluid pipeline and apparatus therefore |
| US5205173A (en) * | 1991-06-21 | 1993-04-27 | Palmer Environmental Services | Method and apparatus for detecting leaks in pipelines using cross-correlation techniques |
| US5189374A (en) * | 1991-10-25 | 1993-02-23 | Burnett Gale D | Method for pulse propagation analysis of a well casing or the like by transmitted pulse interaction |
| US5243294A (en) * | 1991-10-25 | 1993-09-07 | Pipeline Profiles, Ltd. | Methods of and apparatus for detecting the character and location of anomalies along a conductive member using pulse propagation |
| US5270661A (en) * | 1991-10-25 | 1993-12-14 | Pipeline Profiles, Ltd. | Method of detecting a conductor anomaly by applying pulses along the conductor in opposite directions |
| JP3272798B2 (en) * | 1992-01-16 | 2002-04-08 | 株式会社東芝 | Method and apparatus for detecting abnormal position of buried pipe |
| EP0552044B1 (en) * | 1992-01-16 | 1996-10-09 | Kabushiki Kaisha Toshiba | Method and apparatus for detecting the position of an abnormal site of a buried pipe |
| DE4207067C2 (en) * | 1992-03-06 | 1996-07-11 | Herward Prof Dr Ing Schwarze | Method and device for locating a leak in a pipe |
| GB2269900A (en) * | 1992-08-19 | 1994-02-23 | Christopher David Hill | Acoustic leak detection method for liquid storage tanks |
| US5416724A (en) * | 1992-10-09 | 1995-05-16 | Rensselaer Polytechnic Institute | Detection of leaks in pipelines |
| US5675506A (en) * | 1992-10-09 | 1997-10-07 | Rensselaer Polytechnic Institute | Detection of leaks in vessels |
| US5349568A (en) * | 1993-09-27 | 1994-09-20 | The University Of Chicago | Leak locating microphone, method and system for locating fluid leaks in pipes |
| JPH09506974A (en) * | 1994-03-15 | 1997-07-08 | エナジー アンド エンヴァイロメンタル テクノロジーズ コーポレイション | Device and method for detecting ultrasonic waves propagated from a selected distance |
| US5744700A (en) * | 1994-09-20 | 1998-04-28 | Technofirst | Device for detecting and locating fluid leaks |
| US5531099A (en) * | 1994-11-09 | 1996-07-02 | At&T Corp. | Underground conduit defect localization |
| DE69610907D1 (en) | 1995-03-14 | 2000-12-14 | Profile Technologies Inc | Reflectometric method for insulated tubes |
| AU1984597A (en) | 1996-02-27 | 1997-09-16 | Profile Technologies, Inc. | Pipe testing apparatus and method |
| GB9619789D0 (en) * | 1996-09-20 | 1996-11-06 | Palmer Environmental Ltd | Leak noise correlator |
| US5974862A (en) * | 1997-05-06 | 1999-11-02 | Flow Metrix, Inc. | Method for detecting leaks in pipelines |
| US5987990A (en) * | 1997-05-13 | 1999-11-23 | Pipeline Technologies, Inc. | System of autonomous sensors for pipeline inspection |
| US6128946A (en) * | 1997-06-26 | 2000-10-10 | Crane Nuclear, Inc. | Method and apparatus for on-line detection of leaky emergency shut down or other valves |
| GB2326713A (en) * | 1997-06-27 | 1998-12-30 | Cogent Technology Limited | Mole position location |
| GB2333363B (en) * | 1998-01-19 | 2002-04-03 | John Ifan Jones | Water leak detector |
| NO20015325A (en) * | 2001-10-31 | 2002-12-09 | Sintef Energiforskning As | Method and device for acoustic detection and location of sound-generating defects |
| CA2378791A1 (en) * | 2002-03-25 | 2003-09-25 | Mcmaster University | Method of detection of flow duct obstruction |
| US6957157B2 (en) * | 2002-11-12 | 2005-10-18 | Flow Metrix, Inc. | Tracking vibrations in a pipeline network |
| US7891246B2 (en) * | 2002-11-12 | 2011-02-22 | Itron, Inc. | Tracking vibrations in a pipeline network |
| US7642790B2 (en) * | 2003-05-06 | 2010-01-05 | Profile Technologies, Inc. | Systems and methods for testing conductive members employing electromagnetic back scattering |
| EP1629228B1 (en) * | 2003-05-06 | 2017-08-16 | WaveTrue, Inc. | Method for non-destructively testing conductive members employing electromagnetic back scattering |
| US7196529B2 (en) * | 2003-05-06 | 2007-03-27 | Profile Technologies, Inc. | Systems and methods for testing conductive members employing electromagnetic back scattering |
| US6725705B1 (en) | 2003-05-15 | 2004-04-27 | Gas Technology Institute | Enhanced acoustic detection of gas leaks in underground gas pipelines |
| US7567182B2 (en) * | 2004-06-03 | 2009-07-28 | Honeywell International Inc. | Acoustic fire sensing system |
| US20070068225A1 (en) | 2005-09-29 | 2007-03-29 | Brown Gregory C | Leak detector for process valve |
| CN101778791A (en) * | 2007-08-17 | 2010-07-14 | 因温特奥股份公司 | Elevator system having a load carrier condition detector device, and method for detecting a condition of a load carrier |
| NO327674B1 (en) * | 2007-09-12 | 2009-09-07 | Det Norske Veritas As | Device for detecting moisture penetration in an insulation layer by means of acoustic resonance technology |
| US7757708B1 (en) * | 2008-02-25 | 2010-07-20 | nth Solutions | Toilet bowl overflow prevention and water conservation system and method |
| GB2463890A (en) * | 2008-09-26 | 2010-03-31 | Genesis Oil And Gas Consultant | Method of Testing a Pipeline Cut |
| US8310369B1 (en) | 2009-03-27 | 2012-11-13 | Nth Solutions, Llc | Detecting unintended flush toilet water flow |
| CN101571234B (en) * | 2009-06-16 | 2012-05-30 | 北京埃德尔黛威新技术有限公司 | Liquid pressure conduit leak detection device |
| GB0914463D0 (en) * | 2009-08-19 | 2009-09-30 | Sev Trent Water Ltd | Leak detector |
| RU2453760C2 (en) * | 2009-12-18 | 2012-06-20 | Открытое акционерное общество "Газпромнефть" | Method of diagnosing technical state of underground pipelines (versions) |
| CN101832472B (en) * | 2010-06-12 | 2013-03-27 | 中国石油化工股份有限公司管道储运分公司 | System implementing pipeline leak detection by utilizing infrasonic wave |
| CA2859700C (en) * | 2012-01-06 | 2018-12-18 | Hifi Engineering Inc. | Method and system for determining relative depth of an acoustic event within a wellbore |
| EP2902766B1 (en) * | 2012-09-28 | 2018-12-26 | NEC Corporation | Leak detecting device, leak detecting method and program |
| US10386261B2 (en) * | 2013-11-25 | 2019-08-20 | King Abdullah University Of Science And Technology | High repetition rate thermometry system and method |
| RU2568808C2 (en) * | 2014-04-11 | 2015-11-20 | Открытое акционерное общество "Газпром нефть" | Method and device for contactless diagnostics of technical condition of underground pipelines |
| EA028210B1 (en) | 2014-05-14 | 2017-10-31 | Эни С.П.А. | Method and system for the continuous remote monitoring of the position and advance speed of a pig device inside a pipeline |
| CN104132248B (en) * | 2014-07-31 | 2016-10-19 | 重庆大学 | Fluid line leakage detecting and locating method |
| GB2547383B (en) * | 2014-11-25 | 2020-06-24 | Nec Corp | Position estimation device, position estimation system, position estimation method, and computer-readable recording medium |
| NO346618B1 (en) * | 2015-02-24 | 2022-10-31 | Halfwave As | An apparatus and method for inspecting a pipeline |
| JP6384382B2 (en) * | 2015-03-30 | 2018-09-05 | 日本精機株式会社 | Liquid level detection device |
| CN106322127A (en) * | 2016-11-22 | 2017-01-11 | 北京科创三思科技发展有限公司 | Method for installing built-in infrasonic wave sensor |
| US10209225B2 (en) | 2017-04-21 | 2019-02-19 | Mueller International, Llc | Sound propagation comparison with automated frequency selection for pipe condition assessment |
| US10565752B2 (en) | 2017-04-21 | 2020-02-18 | Mueller International, Llc | Graphical mapping of pipe node location selection |
| US10690630B2 (en) | 2017-04-21 | 2020-06-23 | Mueller International, Llc | Generation and utilization of pipe-specific sound attenuation |
| US10948132B2 (en) | 2017-05-08 | 2021-03-16 | 64Seconds, Inc. | Integrity assessment of a pipeline network |
| US10823717B2 (en) | 2017-09-01 | 2020-11-03 | 3M Innovative Properties Company | Wireless power transfer and sensing for monitoring pipelines |
| US10539480B2 (en) | 2017-10-27 | 2020-01-21 | Mueller International, Llc | Frequency sub-band leak detection |
| US10768146B1 (en) | 2019-10-21 | 2020-09-08 | Mueller International, Llc | Predicting severity of buildup within pipes using evaluation of residual attenuation |
| RU2735349C1 (en) * | 2020-05-18 | 2020-10-30 | Общество с ограниченной ответственностью "Научно-производственное предприятие "Техносфера-МЛ" | Diagnostic method of technical parameters of underground pipeline |
| US11726064B2 (en) | 2020-07-22 | 2023-08-15 | Mueller International Llc | Acoustic pipe condition assessment using coherent averaging |
| US11609348B2 (en) | 2020-12-29 | 2023-03-21 | Mueller International, Llc | High-resolution acoustic pipe condition assessment using in-bracket pipe excitation |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3264864A (en) * | 1962-03-01 | 1966-08-09 | American Gas Ass | Apparatus for pinpointing leaks in buried pipes |
| US3903729A (en) * | 1970-12-30 | 1975-09-09 | Taft Broadcasting Corp | Method and apparatus for detecting a break or other occurrence in a pipeline containing gas under pressure |
| US3851521A (en) * | 1973-01-19 | 1974-12-03 | M & J Valve Co | System and method for locating breaks in liquid pipelines |
-
1979
- 1979-10-30 US US06/089,346 patent/US4289019A/en not_active Expired - Lifetime
-
1980
- 1980-10-20 CA CA000362730A patent/CA1141019A/en not_active Expired
- 1980-10-22 GB GB8034024A patent/GB2062864B/en not_active Expired
- 1980-10-30 JP JP15297480A patent/JPS5673331A/en active Pending
- 1980-10-30 FR FR8023221A patent/FR2468898A1/en active Granted
- 1980-10-30 DE DE19803040932 patent/DE3040932A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2468898B1 (en) | 1984-05-25 |
| GB2062864A (en) | 1981-05-28 |
| GB2062864B (en) | 1984-02-15 |
| JPS5673331A (en) | 1981-06-18 |
| US4289019A (en) | 1981-09-15 |
| FR2468898A1 (en) | 1981-05-08 |
| DE3040932A1 (en) | 1981-05-14 |
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