JPH11237234A - Piping inspection method and inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quickly and easily perform piping inspection according to the situation of the site, by detecting direct wave reaching a detection position at first, and estimating the opening position of piping following the sound pressure level for the detecting position of this direct wave. SOLUTION: An inspection device 2 mainly consists of an inspection device body 3, a speaker 4 and an inspection device 5. The inspection device 5 is prepared for a plurality and arranged on ground surface side to be a ground surface side detector 5a picking up sound transmitting in the ground. Here, 7 ground surface side detectors 5a are arranged and the received sound information picked up with these detectors is sent to the inspection device body side to be used for other purposes. By this, pulse sound including a plurality of frequency components is used for the sound inserting in the piping 9. In the case detecting sound at a plurality of positions outside the covering layer, the direct wave reaching the detection position at first is detected and following the sound pressure level distribution corresponding to the detection position of this direct wave, the opening position A is estimated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for determining the position of an opening generated in a pipe which is concealed by a covering layer such as soil or a house wall.

[0002]

2. Description of the Related Art The inventors of the present invention have proposed to transmit a sound wave in a pipe, detect the sound wave from outside the pipe, and search for an opening position of the pipe for the purpose of checking the position of the pipe or the leak position. (Japanese Patent Application No. 7-71167). In this method, as the first step, a sound wave is propagated in the pipe concealed by the coating layer. Then, as a second step, sound waves propagating in the pipe are detected at a plurality of positions outside the coating layer, and a spatial distribution of the detected sound pressure (volume) is obtained. After performing such an inspection, a location where the detected sound pressure (sound volume) becomes maximum is estimated to be, for example, a location where the opening is broken.

[0003] In using this technique, it is preferable to adopt a sound having a frequency which can easily be transmitted through a pipe and can be easily detected from outside the pipe at a high sound pressure. Use sounds of different frequencies.

[0004]

As described above, it is preferable to carry out the inspection by propagating a sound of a specific frequency, but, for example, if the frequency of the propagating sound is fixed, the medium within the tube itself is not allowed. It has been found that detection may be difficult in some cases in relation to natural vibration. Furthermore, if only sound waves having such a natural frequency are used, for example, a sound that resonates at a specific part in a pipe and is transmitted to the outside at a large sound pressure level due to a sound pressure leaking out of the pipe from a part having an opening breakage. It was found that there was a case where the sound was mistakenly regarded as a sound coming from the damaged portion of the opening, and a resonance site other than the damaged portion of the opening was erroneously determined to be the damaged portion of the opening. Such an example will be described with reference to FIG. In the data shown in FIG. 3, the horizontal axis indicates the position of the pipe (unit of distance m) measured from the sound source side, and the vertical axis indicates sound pressure level data detected at each position on the pipe, for example, on the ground. ing. Here, the configuration of the piping used is
It is as shown in FIG. 1, and shows a standing tube on the sound generation side and a main tube to which the standing tube is connected. The horizontal axis in FIG. 3 is a position along the main pipe. In the figure, a sound source is located on the origin side, and an aperture breakage is located at a position indicated by A. In the drawing, the solid line and the dashed line respectively indicate the direct wave from the sound source detected at each detection position and the maximum value of the sound pressure level detected within a predetermined time. Here, the sound generated from the sound source is not a sound of a specific frequency, but a Qingdao pulse sound (this is a pulse sound including a plurality of frequency components. Is a sound that can be obtained by using the measurement technology vol.12-4 pp.35
-43 (1984)). This Qingdao pulse is generated by the optimized Qingdao pulse or TSP (Time-
Stretched Pulse), which is a time signal having a flat power spectrum in a predetermined frequency range,
This is a signal prolonged on the time axis. Morphologically, it is close to an impulse sound, and its frequency band is generally 0
10 kHz.

[0005] As described above, the broken line indicates the maximum value of the sound pressure level detected within a predetermined time.
Generally, it is a so-called sound pressure level detected in a normal state. Now, referring to the detection result at each position, as shown by the broken line in the figure, the sound pressure level detected at the position corresponding to the opening broken position A is high, and the sound pressure level at B located closer to the sound source than this opening broken position is shown. The sound pressure level at the indicated position is also higher in the predetermined section. This part is not a position where the opening is broken, but a normal part. However, the maximum value of the sound pressure level at this position tends to be equal to or higher than that at the position A, and it is difficult to adopt the method described above. Shows the case.

In this example, since the Qingdao pulse sound is used as the inspection sound, the detected sound pressure level at the position B is relatively low. Is selected as a resonance frequency that resonates in the portion B, this tendency becomes more remarkable, and it has been found that this causes misdetection. Here, the resonance in the part B is a problem. However, as a real problem, since the structure of the piping system to be inspected is relatively complicated, the resonance that is likely to cause erroneous detection is determined at what part and how. As to what happens, it may be virtually impossible to grasp this in advance for a particular piping system. Therefore, there is a case where a method of transmitting a sound of a specific frequency into a pipe and grasping a sound pressure level of the propagated sound within a predetermined time is impossible.
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to conduct a pipe inspection capable of promptly and easily proceeding with a leak damage location search for a pipe covered with a coating layer in accordance with the situation at the site. Is to get the way. Another object of the present invention is to provide an inspection apparatus used for such a method.

[0007]

In order to achieve the above object, a first step of transmitting a sound wave in a pipe concealed by a coating layer according to the present invention, and a step of transmitting a sound wave propagating in the pipe outside the coating layer. A second step of detecting at a plurality of positions to obtain a spatial distribution of the detected sound pressure, and an opening position generated in the pipe from the distribution of the detected sound pressure obtained at the second step. The characteristic means of the pipe line inspection method including the third step of estimating the sound wave uses a pulse sound including a plurality of frequency components as the sound wave in the first step, and detects the sound wave at a plurality of positions in the second step. In this case, a direct wave that first arrives at the detection position is detected, and in a third step, an opening position of the pipe is estimated according to a sound pressure level distribution with respect to the detection position of the direct wave. When this method is adopted, a pulse sound including a plurality of frequency components is used as the inspection sound. Then, in the data detected at each inspection position, only the direct sound is used as significant data. This situation will be described with reference to FIG. FIG. 2 shows the result of detection at a specific portion (indicated by A in FIG. 1) along the pipe when the pulse sound is propagated from the sound source side in the pipe system shown in FIG. As can be seen from this figure, the detected sound pressure level at the specific position is in a state where a plurality of maximum values appear.

In the method of the present invention, the sound pressure level of the direct wave is obtained from the data shown in FIG. 2 and is used as significant data. Only the sound pressure level Sp of such a direct wave is detected. The data obtained by organizing this is the data indicated by the solid line in FIG. 3 described above. Here, the sound pressure level of the direct wave is, for example, the maximum sound pressure value detected in a time zone delayed from the time point indicated by C in FIG. 2, that is, it is estimated that the direct wave is detected at the detection position. This is the maximum value of the detected sound detected in a possible time period (this time period can be determined by the distance from the sound source (may be an estimated value) / the sound speed). From this data, it can be seen that the peak of the sound pressure level occurs only in the portion corresponding to the opening, and that the other portions show a relatively low sound pressure level. Therefore, by using the data consisting of the sound pressure level of the direct wave in this way, it is possible to avoid erroneous detection which is considered to be caused by the problem of the acoustic resonance in the tube described above.

[0009] In the first step, it is preferable that a pulse sound capable of obtaining an impulse response is sent into the tube. That is, a so-called one-shot impulse sound, the Aoshima pulse sound described above, and the like are used. By using such a sound, the sound pressure level of the direct wave can be detected relatively easily as, for example, the maximum value of the sound detected in a predetermined time zone. Furthermore, by using Qingdao pulse, it is possible to efficiently apply sound (energy) to the normal impulse sound in the tube, and it is easy to average the response of multiple times, and to obtain highly reliable detection data. Obtainable.

In the method described above, in order to avoid erroneous detection due to the influence of resonance, it has been proposed to perform a so-called inspection based on the sound pressure of a direct wave. It can also be suggested to use the missing sound as a test sound. That is, a first step of transmitting a sound wave in the pipe concealed by the coating layer, and detecting the sound wave propagating in the pipe at a plurality of positions outside the coating layer, and spatially detecting the detected sound pressure. A second step of obtaining a distribution, and performing a pipe inspection including a third step of estimating an opening position generated in the pipe from the distribution of the detected sound pressure obtained in the second step. In one step, a sound excluding a resonance frequency component in a cross-sectional direction of the medium in the pipe is used as the sound wave, and in the second step, sound waves are detected at a plurality of positions, and the sound corresponding to the detected position is detected. The opening position is estimated according to the pressure level distribution. Here, the resonance frequency f in the cross-sectional direction of the medium in the pipe is
It is determined by the following equation. The resonance frequency f in the section direction of the tube in this means is determined by the following equation. f = C × U _mn / (2πa) Here, C is the sound velocity in the pipe (m / s), and is determined according to a known formula based on the pipe contents and the pipe temperature and pressure. A is a pipe radius (m). U _mn is a value that depends on the resonance mode as shown in Table 1 and exists discretely. The information of the gas type, the gas pressure, and the temperature is reference information at the time of deriving the sound velocity C in the pipe.

[0011]

[Table 1]

Each resonance mode corresponds to the vibration pattern shown in FIG. A specific numerical example is as follows.
For methane at ° C., the speed of sound is 434.1 (m / s); for air, the speed of sound is 334.5 (m / s).
At this time, the resonance frequency in the tube having a tube radius of 0.1 (m) is from 1337, 2187, 2732, 2
999, ... Hz. In addition, the air is 10
30, 1685, 2105, 2310,... Hz. Table 2 shows an example of calculation derivation in the case of air under the above conditions. The resonance frequency is calculated on the assumption that the temperature is 20 ° C.

[0013]

[Table 2]

Accordingly, there are an infinite number of discrete resonance frequencies that cause resonance in a so-called cross section in a tube, corresponding to an infinite number of modes. Then, individually, these resonance frequencies can be derived according to the on-site conditions.

By removing the component of the resonance frequency from the inserted sound, it is possible to find, for example, the opening position based on the distribution of sounds of frequencies other than the resonance frequency. In this case, the possibility of erroneous detection due to resonance described above can be reduced. In performing the inspection based on the sound pressure of the direct wave described above, a more accurate inspection can be performed by excluding the resonance frequency component from the insertion sound.

If the resonance frequency component is a problem of erroneous detection, such a resonance frequency component is excluded from the information detected in the second step, and the sum of the sound pressures of the remaining frequency components is calculated. The quantity can also be the inspection data for the aperture. That is, a first step of transmitting a sound wave in the pipe concealed by the coating layer, and detecting the sound wave propagating in the pipe at a plurality of positions outside the coating layer, and spatially detecting the detected sound pressure. A second step of obtaining a distribution, and performing a pipe inspection including a third step of estimating an opening position generated in the pipe from the distribution of the detected sound pressure obtained in the second step. When the detected sound pressure is obtained in two steps, the sound pressure level of the processed sound excluding the resonance frequency component sound in the cross-sectional direction of the medium in the pipe is obtained, and the processed sound corresponding to the detection position is obtained. The opening position is estimated according to the sound pressure level distribution. In this case, by removing a specific frequency component from the sound pressure received in the second step, based on data that is not affected by resonance in the pipe,
The inspection of the opening position can be performed, and the possibility of erroneous detection can be reduced.

In the case where the above pipeline inspection method is used, the required inspection apparatus is preferably configured as follows. That is, a speaker capable of generating a pulse sound including at least a plurality of frequency components in a pipe, and a detection device capable of detecting a propagation sound generated by the speaker and propagating in the pipe to be inspected in accordance with the pipe position. A sound pressure level deriving means for obtaining, in a time domain, a sound pressure level of a propagating sound detected by the detecting apparatus; and a direct wave from the sound pressure data obtained by the sound pressure level deriving means. Direct wave sound pressure level deriving means for obtaining a sound pressure level, and data processing means for performing data processing on the sound pressure level of the direct wave obtained by the direct wave sound pressure level deriving means as data information associated with the detection position, It comprises a display means for displaying data information of the detected position and the direct wave sound pressure level obtained by the data processing means. By doing so, as shown later, the sound pressure level detected corresponding to the pipe position
By obtaining the sound pressure level data of the sound directly from the time data in accordance with the pipe position and displaying this data on a display device, the inspection can be performed by the above method while viewing the display result. Also in this case, it is preferable to provide a means for removing the resonance frequency component for controlling the input to the speaker so as to insert the pulse sound from which the resonance frequency component has been excluded. On the other hand, also in the processing of the detected sound, it is preferable to provide a means for removing the resonance frequency component on the detection side, which removes the resonance frequency component from the detected sound component.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a state in which the pipe inspection method of the present invention is applied to search for an opening breakage A generated in a gas pipe 1 buried underground. In this method, a sound wave propagating in the pipe 1 is used for searching for the opening breakage portion A.

In the pipeline inspection of the present application, an inspection apparatus 2 having a configuration unique to the present application is used. First, an outline of the inspection device 2 will be described. The inspection device 2 includes an inspection device main body 3, a speaker 4, and a detection device (microphone or vibration pickup) 5 as main components. Here, the speaker 4 is an explosion-proof type,
It is configured to be attachable to the pipe end 6 exposed on the ground. The speaker 4 is configured to be driven to generate a predetermined sound wave in response to a sound generation command from the inspection apparatus main body side, and to send a pulse sound including at least a plurality of frequency components into a tube to be inspected. . Next, the detection device 5 will be described. A plurality of the detection devices 5 are provided, and the detection device 5 is a ground-side detection device 5a that is disposed on the ground surface side and picks up sound propagating from underground. In the example shown in FIG. 1, seven ground-side detection devices 5a are provided, and the sound reception information picked up by these detection devices is sent to the inspection device main body side for use later. Is done.

Next, the configuration of the inspection apparatus main body 3 will be described. Qingdao pulse generating means 3 which stores predetermined information for generating Qingdao pulse sound from speaker 4
1. a sound pressure level deriving means 32 for calculating the sound pressure level of the sound detected by each of the detection devices 5 in relation to a lapse of time from the time of sound generation in the sound source;
2, the direct wave sound pressure level deriving means 33 for deriving the maximum value (this corresponds to the sound pressure level of the direct wave) from the sound pressure level data obtained over time, and the position of the ground-side detection device 5a (this position Are separately input from the input device 34), and data processing means 35 for associating the direct wave sound pressure level of the received sound detected by each detection device 5a with the data processing means 35. Further, from the data arranged as the spatial position-direct wave sound pressure level data by the data processing means 35, a predetermined spatial area (for example, an area whose position coordinate is larger than S in FIG. 3).
The direct wave sound pressure level maximum position deriving means 36 for determining and marking the maximum value in is provided.

With reference to FIG. 1, the basic principle of the inspection method of the present invention will be described below for the case where the gas pipe 1 (an example of a buried pipe) buried in the front road of each home 7 is targeted. FIG. 1 shows a city gas piping system B that supplies city gas to each household 7. That is, each household 7 is provided with a low-pressure gas pipe 9 buried in a front road 8, and from this low-pressure gas pipe 9, a drawing pipe 1 is provided.
The pipes drawn into the premises of each household 7 through 0
After being once put out as a standing pipe 11 above the ground, the pipe is connected to a gas supply position (not shown) in each home. This standing pipe 1
A so-called gas meter (not shown) is provided at the predetermined position of the first position. In the exploration work, a gas meter (not shown) is removed from the standing pipe 11 to use the above standing pipe 11, and the speaker 4 is attached to the pipe end 6 of the standing pipe 11. The speaker 4 receives information from the Qingdao pulse generation means 31 described above and receives a control command, and sends a pulse sound containing a plurality of frequency components into the tube.

On the other hand, a plurality of ground-side detection devices 5a are arranged on the ground along the buried positions of the gas pipes 1 prepared in advance. Therefore, these detection devices 5a can pick up sound waves leaking into the ground from inside the tubes corresponding to the respective sound receiving regions. Information from the front-side detection device 5a is collected in the inspection device main body 3 and the sound pressure level deriving means 3 is provided.
2, the sound pressure level is obtained in the time domain, and the sound pressure level of the direct wave (the maximum value of the direct wave) is specified by the direct wave sound pressure level deriving means 33. Here, when considering the propagation of the Qingdao pulse wave in identifying the direct wave, it is basically determined that the sound pressure level of the maximum peak in a predetermined time zone is due to the detection of this direct wave. This is specified as this sound pressure level. Here, the time zone for calculating the maximum value is set in advance as a time zone (evaluation time zone in FIG. 2) in which the direct wave can be estimated to reach this detection position from the positional relationship between the detection position and the sound source. When it is necessary to determine whether or not a direct wave has arrived, when there is no sound reception and when there is sound reception, a state in which the state is larger than the threshold is compared with a preset threshold. A state where there is a sound and a state smaller than the threshold are determined as a state where no sound is received. Such information is stored in the data processing unit 3
5, the data is arranged as direct wave sound pressure level data corresponding to the position of the front side detection device 5a. Here, the position information of each front side detection device 5a is separately input in advance from an input device 34 provided in the device. That is, on the main body side, the data is arranged as shown in FIG. 3 and arranged as spatial position-direct wave sound pressure level data. By the way, the information obtained in this way is determined by the direct wave sound pressure level maximum position deriving means 36 in a predetermined area to determine a spatial position where the sound pressure level is maximum, and this position is specified. It is estimated that the position is the opening breakage position A. The data and the specific position can be displayed on the display device 37. Here, the processing by the direct wave sound pressure level maximum position deriving means 36 finds the maximum value at a position further away from the sound source side than the preset position S shown in FIG. In the case where such processing is performed, in the propagation state of the pulse sound including a plurality of frequency components, the characteristic that the sound pressure level decreases as the detection position is further away from the sound source, the lower the sound pressure level becomes. Since it is common to have exponential function fitting for the obtained spatial position-direct wave sound pressure level data, the maximum value is obtained only for the value obtained by dividing the obtained fitting data from the original data. The required configuration may be adopted.

Hereinafter, the working procedure will be described more specifically. 1 The worker 12 arrives at a work site 13 as shown in FIG. At this point, a burying map indicating the burying position of the gas pipe 1 near the site is prepared. Therefore, the buried position and the direction of the pipe 1 are known in advance. If it is difficult to obtain such information, the position of the pipe 1 is confirmed using an underground radar (not shown) or the like, and the pipe 1 is located at least above the buried pipe on the ground side. 2. A gas meter (not shown) of a specific home 7 is removed from the standpipe 11, and the speaker 4 is attached to the end 6. (3) On the other hand, a plurality of ground-side detection devices 5a are arranged at positions on the buried pipe that are known in advance. This positional relationship (specifically, the distance from the standpipe) is input from the input device 34 into the inspection device main body, and is processed by the data processing unit 35. 4 After the completion of such a preparation step, the Qingdao pulse generating means 31 operates to cause the Qingdao pulse sound (band 0 to 10 kHz) to propagate from the speaker 4 into the tube. 5. The Qingdao pulse sound propagating in the pipe is sequentially propagated in a direction away from the speaker 4 on the sound emitting side. In this state, on the ground side, the sound receiving data is collected by the front-side detection devices 5a arranged at the positions on the pipes along the arrangement direction. 6 As described above, the detection signal detected by the ground-side detection device 5a is sent to the inspection device main body 3, and first, the sound pressure level deriving means 32 changes the sound pressure level as the data shown in FIG. Specified with. Then, the sound pressure level of the direct wave is specified by the direct wave sound pressure level deriving means 33 from this data. It is a sound pressure level at a point marked by Sp shown in FIG. Next, data from each detection device is sent to the data processing means 35, the sound pressure level of each direct wave is arranged in relation to the spatial position, and the direct wave sound pressure level of the configuration shown by the solid line in FIG. And the direct wave sound pressure level maximum position deriving means 3
6, the position where the sound pressure level of the direct wave is maximum in the predetermined area is specified. For example, the display device can be marked. 7. The information arranged as described above is sent to the display device 37 provided in the inspection apparatus main body 3 so that the operator can visually check the information. As a result, the operator can specify a position on the pipe that is likely to be the opening breakage position A according to the marking.

[Another Embodiment] (a) In the above embodiment, the Qingdao pulse sound is used. However, in the application of the present invention, a pulse sound composed of sounds of a plurality of frequency components is used. Any sound can be used. Further, for example, it is preferable to use a sound including almost all frequency components called an impulse sound. Such sounds are collectively referred to as pulse sounds including a plurality of frequency components. As such a sound, a rectangular wave or a triangular wave that emits a sound wave only for a predetermined time period can be used. (B) In the embodiments described so far, an example in which a so-called Qingdao pulse is used has been described. However, in the present application, the resonance frequency component of the sound is also affected by the sound to be inserted into the pipe. It has been found that the detected sound (or vibration caused by the sound) also poses a problem. Therefore, similarly, even when the Qingdao pulse is used, for example, a sound (for example, a sound in a band of 50 to 800 Hz) obtained by removing the resonance frequency component of the pipe can be used as the inspection sound. For example, if the radius in the pipe is 0.1 m, the gas existing in the pipe is air, and the temperature is 5 ° C. and the pressure is 1 atm, the resonance frequency of the gas in the cross section of the pipe in the pipe is approximately 10
30, 1685, 2105, 2310,... Hz. Therefore, by using the Qingdao pulse in which the frequency component higher than 800 Hz is cut using a filter or the like, inspection data can be easily obtained from the influence of resonance in the cross-sectional direction of the tube. In this case, a wave of a harmonic or the like higher than the resonance frequency tends to be a problem, but the object of the present application can be easily achieved by cutting all the frequency components larger than the minimum frequency component among the resonance frequencies in the sectional direction. . An explanatory diagram of such a configuration is shown in FIG. 4 corresponding to FIG.
In FIG. 4, the diameter of the pipe to be inspected and the type, pressure and temperature of the medium inside the pipe are checked in advance, and the resonance frequency is determined from the diameter of the pipe and the sound speed inside the pipe. The derivation of the resonance frequency follows the equation described above. And a frequency band including this frequency (for example, a frequency band higher than 800 Hz)
Is input to the Qingdao pulse generating means. In this way, in the generation of the Qingdao pulse or in the filtering process after the generation, the signal excluding the predetermined frequency band is sent to the speaker 4 side, and the desired inspection can be performed. FIG. 5 shows the result of the detection performed in this manner. In FIG. 5, a portion having a distance of 0 is a position corresponding to the point A described above, and the horizontal axis represents a separation distance in the tube axis direction. On the other hand, the vertical axis indicates the maximum amplitude (volt) corresponding to the sound pressure of the direct sound. In the figure, the solid line is a general Qingdao pulse, and the dashed line is the result of a pseudo Qingdao pulse subjected to a specific band limitation. For a highly accurate inspection in such a narrow region, it is preferable to use a pulse excluding the resonance frequency component from the viewpoint of its position and sound pressure distribution. As described above, in the method of removing the resonance frequency component from the inserted sound, it is preferable to use the sound pressure of the direct sound in determining the sound pressure as described above, but it is not always necessary to directly use the sound pressure in the second step. It is not necessary to detect the sound, and the integrated value of the sound detected in a certain time zone can be used as the sound pressure. Further, since there is no need to detect a direct sound, a pulse sound need not be selected as a sound to be inserted, and a continuous sound may be used.

(C) In the example of (b), it is proposed to remove a component sound having a resonance frequency that can be specified in advance from the sound to be inserted into the pipe. Although shown, the processing for removing such resonance frequency components may be performed on the detection side. For example, in the main embodiment described above, a pulse sound (Aoshima pulse sound) that can obtain an impulse response in the sound in the pipe is inserted as the insertion sound. Then, on the detection side, by reproducing the impulse response, the intensity of the impulse response can be determined as the sound pressure of the detected sound. In the case of employing such a sound pressure determination method, the correlation between the detected sound and the incoming sound signal (in this signal, the resonance frequency component, for example, a sound of 800 Hz or higher is not removed) is used. By taking this, an impulse response can be obtained. In this case, the resonance frequency component is substantially removed. As a result, such correlation processing plays a role of a digital filter, and a sound pressure from which a resonance frequency component has been removed can be obtained, thereby achieving the object of the present application. In addition to the above-described correlation processing, direct filtering processing can be performed depending on the type of the inserted sound. That is, according to the above example, 800 Hz
By cutting off higher frequency sounds, the sum of the spectra in other bands may be detected as sound pressure. By performing such processing, data with a low possibility of erroneous detection can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a state in which an opening damaged portion of a gas pipe is being searched for using the inspection method of the present application.

FIG. 2 is a diagram showing a state of a detected sound in a time domain.

FIG. 3 is a diagram showing a spatial distribution of a sound pressure level of a direct sound.

FIG. 4 is an explanatory diagram in the case of using a Qingdao pulse whose band is limited.

FIG. 5 is a diagram showing a detection state in a case where a Qingdao pulse whose band is limited is used;

FIG. 6 is a diagram showing a vibration mode and a vibration state in a pipe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas piping 2 Inspection apparatus 4 Speaker 5 Detector 5a Surface side detector 32 Sound pressure level deriving means 33 Direct wave sound pressure level deriving means 34 Input device 35 Data processing means 36 Direct wave sound pressure level maximum position deriving means A Opening breakage

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Masaki Kishi 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Osaka Gas Co., Ltd. (72) Inventor Masao Aoki 1-Migadaidai, Nishi-ku, Kobe-shi, Hyogo Prefecture 3-7301

Claims (6)

[Claims] A first step of transmitting a sound wave in a pipe concealed by a coating layer; detecting a sound wave propagating in the pipe at a plurality of positions outside the coating layer; A second step of obtaining a spatial distribution, and a third step of estimating an opening position generated in the pipe from a distribution of the detected sound pressure obtained in the second step. In the first step, a pulse sound including a plurality of frequency components is used as the sound wave, and when sound waves are detected at a plurality of positions in the second step, a direct wave that first reaches a detection position is detected. A pipe inspection method for estimating the opening position according to a sound pressure level distribution corresponding to a detection position of the direct wave in the third step. 2. The pipeline inspection method according to claim 1, wherein in the first step, a pulse sound capable of obtaining an impulse response is sent into the pipe. 3. The pipeline inspection method according to claim 1, wherein the pulse sound including a plurality of frequency components as the sound wave is a sound from which a resonance frequency component in a cross-sectional direction of a medium in the pipe is removed. 4. A first step of propagating a sound wave in a pipe concealed by a coating layer, and detecting the sound wave propagating in the pipe at a plurality of positions outside the coating layer. A second step of obtaining a spatial distribution, and a third step of estimating an opening position generated in the pipe from a distribution of the detected sound pressure obtained in the second step. In the first step, a sound obtained by removing a resonance frequency component in a cross-sectional direction of the medium in the pipe is used as the sound wave. In the second step, sound waves are detected at a plurality of positions. A pipe inspection method for estimating the opening position in accordance with a sound pressure level distribution corresponding to (1). 5. A first step of transmitting a sound wave in a pipe concealed by a coating layer, and detecting a sound wave propagating in the pipe at a plurality of positions outside the coating layer to detect a sound pressure to be detected. A second step of obtaining a spatial distribution, and a third step of estimating an opening position generated in the pipe from a distribution of the detected sound pressure obtained in the second step. When the detected sound pressure is obtained in the second step, the sound pressure of the processed sound excluding the sound of the resonance frequency component in the cross-sectional direction of the medium in the pipe is obtained, and the processing corresponding to the detected position is performed. A pipe inspection method for estimating the opening position according to a sound pressure level distribution of a finished sound. 6. A speaker capable of generating a pulse sound including at least a plurality of frequency components in a pipe, and a detection device capable of detecting a propagation sound generated by the speaker and propagating in the pipe corresponding to a pipe position. A sound pressure level deriving means for obtaining a sound pressure level of the propagation sound detected by the detecting device in a time domain, and a sound pressure level directly obtained from the sound pressure data obtained by the sound pressure level deriving means. Direct wave sound pressure level deriving means for obtaining a sound pressure level of a wave; and data processing means for processing the sound pressure level of the direct wave obtained by the direct wave sound pressure level deriving means as data information associated with the detection position. An inspection apparatus comprising a display unit for displaying data information of a detection position and a direct wave sound pressure level obtained by the data processing unit.