JP2006300854A - Piping plate thickness measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piping plate thickness measuring device that simply, reliably and precisely measures a plate thickness of piping such as a nuclear power plant, a thermal power plant and a chemical plant by non-destructiveness. <P>SOLUTION: The piping plate thickness measuring device includes a signal input sensor 1 for inputting an input signal by an ultrasonic wave set previously arbitrarily to piping 3 and a detection sensor 2 for detecting a lamb wave generated by responding to the input signal of the signal input sensor 1. The piping plate thickness measuring device measures the plate thickness of the piping 3 by finding a propagation speed between sensors of specific frequency mechanical vibration between the signal input sensor 1 and the detection sensor 2 on the basis of propagation speed distribution of the lamb wave. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pipe thickness measuring device that measures the thickness of a pipe such as a steam pipe in a nuclear power plant, a thermal power plant, etc., or a gas pipe that transports a gas such as natural gas or hydrogen gas.

  Conventionally, pipe thickness measuring devices have used ultrasonic waves to measure the thickness of various pipes, and are basically based on reflection from the bottom surface. It can be said that it is a spot measurement to measure automatically.

  A conventionally known pipe thickness measuring apparatus is an ultrasonic pipe thickness measuring apparatus provided with means for continuously measuring the thickness of a steel pipe using an ultrasonic reflection echo and an abnormal data processing means. The tube thickness measuring device includes an amplifier that amplifies the echo to a preset intensity and a determination circuit that determines whether or not the echo is within a predetermined intensity range. And a plurality of previous value tracking means for sequentially tracking (see, for example, Patent Document 1).

  Further, a material thickness measuring method and apparatus are known that can measure the material thickness with high accuracy with a simple configuration even if the material temperature fluctuates. The material thickness measuring device is for irradiating a laser on the surface of the material to generate ultrasonic waves inside the material, and calculating the material thickness based on the propagation time of the longitudinal wave and the mode converted wave in the material. (For example, refer to Patent Document 2).

In addition, non-destructive inspection methods for piping are known. This non-destructive inspection method for piping is capable of inspecting the adhesion form of steam oxidation scale over a wide range of the inner surface of the piping easily in a short time. The pipe is scanned in the circumferential direction and the longitudinal direction of the pipe in a non-contact manner with the pipe from the outside, and the thickness, delamination and lift of the steam oxidation scale adhering to the inner surface of the pipe are inspected. In addition, based on the inspection result by the electromagnetic ultrasonic inspection apparatus, the adhesion form of the steam oxidation scale is displayed in different colors with the inner surface of the pipe being developed in the circumferential direction. In addition, the thickness of the steam oxidation scale may be displayed by changing the color gradation according to the thickness (see, for example, Patent Document 3).
JP 2000-275035 A JP 2004-157114 A JP 2004-45124 A

  However, it is hoped that the pipe thickness measuring device will be able to measure the thickness of pipes over the entire area for steam piping at nuclear power plants, thermal power plants, etc., piping for chemical plants, gas piping, water piping, etc. For example, it is possible to determine whether there is no thinned area in the area by measuring the average thickness of the pipe in a predetermined section of the pipe. It has been desired that the piping can be measured easily and accurately without damage without damaging it.

  In order to solve the above problems, the object of the present invention is to measure the plate thickness of piping in nuclear power plants, thermal power plants, chemical plants, etc., and the ultrasonic wave transmitted through the piping depends on the plate thickness and frequency. Focusing on the propagation of waves with velocity dispersion, the Lamb wave is used to measure the thickness of pipes easily and accurately with non-destructive use of this velocity dispersion characteristic, and the accuracy of the measurement results is easy. In particular, the measurement results can be displayed. Specifically, multiple sensors can be separated from each other and installed in the pipe to measure the average plate thickness between the sensors. It is providing the pipe plate thickness measuring apparatus which can also measure.

  The present invention detects one signal input sensor for inputting an input signal by an ultrasonic wave arbitrarily set in advance to a pipe, and a Lamb wave generated in response to the input signal of the signal input sensor. One or more detection sensors, and determining the propagation speed between sensors of a specific frequency mechanical vibration between the signal input sensor and the detection sensor based on the propagation speed dispersion of the Lamb waves. The present invention relates to a pipe plate thickness measuring apparatus characterized by measuring a plate thickness.

  The signal input sensor inputs one or more frequencies of the input signal, the distance between the signal input sensor and the detection sensor, the material of a plate member such as a pipe, and various setting conditions. A function of displaying the plate thickness with respect to the frequency of the input signal and the average value thereof as individual numerical values or plotting them on the characteristics of the propagation speed of the Lamb wave and the frequency It is what has.

  The input signal is a signal composed of a single frequency component in a range of 100 Hz to 20 MHz, which is changed according to the thickness of the pipe. The frequency of the input signal is used in the range of the A0 mode not including the A1 mode or higher which is the lowest-order antisymmetric mode of the Lamb wave. For example, when the pipe is an aluminum plate, the product (fw) of the frequency (f) of the A0 mode not including the A1 mode and the plate thickness (w) is approximately fw <1.5 MHz mm. If the plate thickness w is 10 mm, the frequency f is f <150 kHz, and measurement is performed using frequency components below this value.

  Further, the input signal has a function of selecting and inputting only one signal composed of the single frequency component or a plurality of different frequency components. For example, the measurement is performed with a plurality of single frequency components such as 20, 50, 80, and 100 kHz at 150 kHz or less, and a plurality of points are plotted on the propagation velocity-frequency characteristic curve. Become.

  The signal input sensor and the detection sensor induce the Lamb wave in the A0 mode in the measurement object regardless of contact or non-contact with the plate member of the pipe, which is the measurement object, and output the detection signal. Use what you can get. The detection signal from the detection sensor is amplified by an amplifier and has a filter function for extracting only the same frequency component as the input signal.

The pipe plate thickness measuring apparatus has a function of averaging the input signal and the detection signal a plurality of times to improve the S / N of the input signal and the detection signal.
For the averaging, one frequency is changed once, the frequency f is changed once, the same frequency f is changed a plurality of times, different frequencies f are changed a plurality of times, or the average of all or all of these averages are calculated. pointing. That is, with respect to averaging, for example, for the frequencies f1, f2, f3, and f4, the first averaging is an average of multiple measurements by f1 and an average of multiple measurements by a1 and f2. The average of a plurality of measurements by a2 and f3 is a3, and the average of a plurality of measurements by f4 is a4. In the second averaging, the average of a1, a2, a3, and a4 is a. In the third averaging, the average obtained by one measurement at each frequency of f1, f2, f3, and f4 is A, and these averages are included.

  Further, this pipe plate thickness measuring apparatus measures a propagation time Δt from the input signal oscillation to the detection signal arrival. Furthermore, the distance between the signal input sensor and the detection sensor is a length L that can be arbitrarily set, and a signal is input to the signal input sensor as the length L. Alternatively, a plurality of sensor distances may be stored in advance, and a jig that can immediately set the sensor mounting position corresponding to the distances may be attached. Further, this pipe plate thickness measuring device has a function of obtaining a propagation velocity vf for the input signal from the propagation time Δt and the length L. Further, this pipe plate thickness measuring device has a function of inputting the material of the pipe, and has a database of theoretical velocity dispersion characteristics of the A0 mode which is the non-target mode of the Lamb wave of the material. .

  This pipe plate thickness measuring device has a function of plotting the characteristic of the relationship between the propagation speed and the frequency as an indication of the propagation speed vf. In addition, on the propagation velocity-frequency characteristics, a function that can display a theoretical curve for the thickness of each pipe thickness, for example, 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 5 mm, 10 mm, etc. It is to have. By simply looking at the correlation between this theoretical thickness curve and the obtained plot, the thickness can be easily and clearly read with high reliability.

  The pipe plate thickness measuring device has a function of displaying the plate thickness data of the pipe on a display unit and transmitting and displaying the data to a remote place wirelessly or by wire. Further, this pipe plate thickness measuring device has a memory for storing the plate thickness data of the pipe and has a function of displaying the results measured at different sensor positions. As a result, if the plate thickness of the pipe is the same by changing the position of the same pipe and measuring the plate thickness, the same result is displayed, and the measurement result of the plate thickness can be confirmed immediately with reliability. . If the measurement results of the plate thickness are different, the distribution of the plate thickness can be measured by subdividing and changing the sensor distance and measuring the plate thickness in the vicinity.

  Since this pipe thickness measuring device is configured as described above, when mechanical vibrations, for example, an ultrasonic signal is input to the piping of a nuclear power plant, thermal power plant, chemical plant, etc., the pipe thickness and its A wave called a Lamb wave having velocity dispersion depending on the frequency of the signal propagates through the pipe. Therefore, the pipe thickness can be measured based on the theory of Lamb wave velocity dispersion characteristics by setting the frequency of the input signal and measuring the propagation velocity of the known frequency component. In addition, by inputting multiple signals by changing the frequency of the input signal, and displaying the measurement results so that the pipe thickness can be read intuitively as in the speed-frequency characteristics, the reliability of the measurement Can be improved.

  The pipe thickness measuring device according to the present invention is generally used to measure the thickness of pipes of nuclear power plants, thermal power plants, chemical plants, gas, water, hydrogen systems, etc. Focusing on the propagation of waves with a Lamb wave with velocity-dependent velocity dispersion, the pipe thickness is measured using this velocity dispersion characteristic. Specifically, this pipe thickness measuring device uses at least two ultrasonic sensors, ie, an input sensor and an output sensor, to determine the frequency component of the propagation signal, the sensor distance, and the measured propagation velocity. The thickness is calculated from this value. At this time, changing the frequency to obtain multiple speeds and plotting the “speed-frequency characteristics” makes it possible to intuitively read the pipe thickness, and matches the theoretical curve of the thickness with the characteristics. If not, it is possible to confirm at a glance whether there is a place where the thickness is locally different or whether there is an error in the measurement, which makes it possible to measure the thickness with high reliability. Further, the distribution of the plate thickness of the three-dimensional pipe can be obtained by changing the sensor mounting position and the sensor interval. This pipe plate thickness measuring apparatus is preferably applied to a cylindrical pipe, and it is needless to say that various conditions such as reflection must be corrected for a square pipe or the like.

  Hereinafter, embodiments of a pipe plate thickness measuring apparatus according to the present invention will be described with reference to the drawings. This pipe thickness measuring device is capable of nondestructive and simple and accurate inspection of the thickness of parts that require strict control of the pipe thickness of nuclear power plants, thermal power plants, chemical plants, etc. In addition to displaying the pipe thickness values as in the conventional equipment, the pipe thickness is displayed visually, that is, visually, in detail, in order to display the speed-frequency characteristic curve in detail. It was possible to intuitively judge whether the measured value of the pipe thickness was correct, and it was possible to measure the thickness of the pipe with high reliability.

  FIG. 1 shows an embodiment of a pipe plate thickness measuring apparatus according to the present invention. This pipe plate thickness measuring device is generated in response to an input signal of one signal input sensor 1 for inputting an input signal by an ultrasonic wave arbitrarily set in advance to the pipe 3 and the signal input sensor 1. One or more detection sensors 2 for detecting Lamb waves, and the propagation speed between sensors of a specific frequency mechanical vibration between the signal input sensor 1 and the detection sensor 2 is determined by the propagation speed dispersion of the Lamb waves. The plate thickness of the pipe 3 is measured by obtaining based on the above.

  Specifically, this pipe plate thickness measuring device includes a pipe 3 with a signal input sensor 1 at a place where the thickness of the pipe 3 is measured and a detection sensor 2 at a position separated from the signal input sensor 1 by a distance L. And are set. The detection sensor 2 can be provided at a plurality of locations with respect to the pipe 3. An input signal from the signal generation circuit 4 is input to the signal input sensor 1. The signal generation circuit 4 operates by processing of signal generation from the input unit 5 and generates an input signal based on a predetermined ultrasonic wave. The input unit 5 is preset with information on the frequency, the material of the plate member of the pipe 3, and the distance L between the signal input sensor 1 and the detection sensor 2, and the input signal determined according to the information. Is generated from the signal generation circuit 4. The input signal generated by the signal generation circuit 4 is sent to the measurement analysis unit 7. Information from the input unit 5 is input to the piping material physical property database 6, and in the piping material physical property database 6, theoretical plate thickness and propagation velocity information obtained from the piping material and frequency are sent to the measurement analysis unit 7. It is.

  On the other hand, the signal measured by the detection sensor 2 is a detection signal for Lamb wave information having velocity dispersion depending on the thickness of the pipe 3 and the frequency of the signal, and is sent to the amplifier 8 and amplified. The amplified signal is sent from the amplifier 8 to the input frequency component extraction filter 9 to extract the input frequency component. The input frequency component extracted by the filter 9 is input to the measurement analysis unit 7. Further, the measurement analysis unit 7 in this pipe plate thickness measuring device obtains the propagation velocity vf with respect to the input signal frequency from the time difference of the input detection signal, that is, the propagation time Δt and the length L, and the theory from the physical property database 6 of the pipe material. It has the function of deriving the plate thickness by comparing and analyzing the typical propagation velocity. In the measurement analysis unit 7, the detected input frequency component is analyzed in consideration of information in the piping material physical property database 6 and the signal generation circuit 4. The detection results of the plate thickness, Lamb wave propagation time Δt, and propagation velocity vf, which are analyzed and derived by the measurement analysis unit 7, are displayed on the display unit 10 and recorded in the memory 11.

  This pipe plate thickness measuring apparatus includes one or more frequencies of an input signal, a distance L between sensors between the signal input sensor 1 and the detection sensor 2, a material of a plate member of the pipe 3, and various setting conditions. With the function of inputting the thickness of the input signal with respect to the frequency of the input signal and the average of those values as individual numerical values or plotting them on the characteristics of the propagation speed and frequency of Lamb waves It is. Here, the input signal is a signal composed of a single frequency component in the range of 100 Hz to 20 MHz, which is changed according to the plate thickness of the pipe 3. Further, the frequency of the input signal is used in a range not including the Al mode or higher which is the lowest order antisymmetric mode. The asymmetric mode is indicated by A0, A1, A2... From the lower phase velocity, and the symmetric mode is indicated by S0, S1, S2. Each natural vibration mode of the Lamb wave exhibits strong dispersibility in which the propagation speed Δt varies depending on the frequency. For example, when the pipe 3 is an aluminum plate, the product (fw) of the frequency (f) in the range of the A0 mode not including the Al mode and the plate thickness (w) is approximately fw <1.5 MHz mm. If the plate thickness w of the pipe 3 is 10 mm, the frequency f is f <150 kHz mm, and measurement is performed using frequency components below this value.

  The input signal has a function of selecting and inputting only one signal composed of a single frequency component or a plurality of different frequency components. For example, the thickness w of the pipe 3 is 150 kHz or less, and measurement is performed with a plurality of single frequency components such as 20 kHz, 50 kHz, 80 kHz, and 100 kHz. Will be plotted. Further, the plate thickness w of the pipe 3 can be measured by inputting it several times at the same frequency f or a plurality of different frequencies f and calculating the average of these values.

  In this pipe plate thickness measuring device, the signal input sensor 1 and the detection sensor 2 induce A0 mode Lamb waves in the measurement object regardless of contact or non-contact with the plate member of the pipe 3 as the measurement object. , Which can acquire a detection signal is used. The detection signal from the detection sensor 2 is amplified by the amplifier 8, and only the same frequency component as the input signal is extracted by the input frequency component extraction filter 9 having a filter function.

  In addition, this pipe plate thickness measuring apparatus uses only one measurement of the input signal from the signal input sensor 1 and the detection signal from the detection sensor 2, or averaging multiple times to determine the signal / noise between the input signal and the detection signal. It has a function to improve (S / N). Further, this pipe plate thickness measuring device measures the propagation time Δt from the input signal oscillation to the detection signal arrival, and these pieces of information are information obtained by analysis by the measurement analysis unit 7. In addition, the distance between the signal input sensor 1 and the detection sensor 2, that is, the length L can be arbitrarily set, and a signal of length L is sent from the input unit 5 to the measurement analysis unit 7 through the piping material physical property database 6. It is input. In this pipe plate thickness measuring device, the propagation speed vf is obtained from the propagation time Δt and the length L, and the plate thickness w of the pipe 3 is obtained from the material, the frequency f and the propagation speed vf. Alternatively, the CPU may store a plurality of sensor distances in advance, and a jig that can immediately set the sensor distance corresponding to the distances may be attached.

  In addition, this pipe plate thickness measuring device has a function of inputting the material of the plate member of the pipe 3, and has a database of theoretical velocity dispersion characteristics of the A0 mode that is the non-target mode of the Lamb wave of the material. Is. This pipe plate thickness measuring device has a function of plotting the characteristic of the relationship between the propagation speed and the frequency as an indication of the propagation speed vf. In addition, on the propagation speed-frequency characteristics, a function that can display theoretical curves for thicknesses of each pipe thickness, for example, 0.1 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 5 mm, 10 mm, etc. It is to have. By simply looking at the correlation between this theoretical thickness curve and the obtained plot, it is possible to easily and accurately read the plate thickness with high reliability.

  The pipe thickness measuring device has a function of displaying the thickness data of the pipe 3 on the display unit 10 and transmitting and displaying the data wirelessly or by wire to a remote place. The pipe plate thickness measuring device has a memory 11 for storing the plate thickness data of the pipe 3 and has a function of displaying the results measured at different sensor positions. As a result, if the plate thickness of the pipe is the same by changing the position of the same pipe and measuring the plate thickness, the same result is displayed, and the measurement result of the plate thickness can be confirmed immediately with reliability. . In addition, this pipe thickness measuring device can measure the surface thickness distribution in detail by subdividing and measuring the thickness of the surrounding area by changing the sensor distance.

  In FIG. 2, the propagation velocity-frequency characteristic displayed on the display unit 10 is shown as a curve. For the plate thickness w (mm) of the pipe 3, the relationship of the vertical axis propagation device (m / s) to the horizontal axis frequency: f (kHz) is shown. The plate thickness of the pipe 3 in FIG. 2 is 0.1 mm, 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, 5.0 mm, and 10.0 mm. Although not shown, the display unit 10 is configured so that the plate thickness w, the frequency f, and the propagation velocity vf of the pipe 3 can be digitally displayed. This pipe plate thickness measuring device can digitally display the plate thickness w at each frequency f, the value at the same frequency f, or the average value and each value at all frequencies f.

3 and 4 show curves of propagation velocity-frequency characteristics when the plate material of the pipe 3 is made of iron (Fe). The numerical value of the frequency f on the horizontal axis varies depending on the plate thickness w of the pipe 3. The propagation speed is m / s, and the frequency f has a unit of kHz or MHz.
The curve in FIG. 3A shows that the plate thickness w of the pipe 3 is 0.1 mm, 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, 5.0 mm, and 10.0 mm, and the frequency f The numerical value of is 0 to 200 kHz. In addition, the curve in FIG. 3B shows that the thickness w of the pipe 3 is 5.0 mm, 10.0 mm, 15.0 mm, 20.0 mm, 30.0 mm, and 50.0 mm. Is 0 to 40 kHz.
In the curve in FIG. 4, the plate thickness w of the pipe 3 is 30.0 mm, 50.0 mm, 80.0 mm, and 100.0 mm, and the numerical value of the frequency f is 0 to 20 kHz.
As can be seen from FIGS. 3 and 4, the frequency becomes lower as the thickness of the pipe 3 increases.

5 and 6 show curves of propagation velocity-frequency characteristics when the plate material of the pipe 3 is made of aluminum (Al). The numerical value of the frequency f on the horizontal axis varies depending on the plate thickness w of the pipe 3. The propagation speed is m / s, and the frequency f has a unit of kHz or MHz.
The curve in FIG. 5A shows that the plate thickness w of the pipe 3 is 0.1 mm, 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, 5.0 mm, and 10.0 mm, and the frequency f The numerical value of 0 to 20 kHz. Further, the curve in FIG. 5B shows that the thickness w of the pipe 3 is 5.0 mm, 10.0 mm, 15.0 mm, 20.0 mm, 30.0 mm, and 50.0 mm, and the unit of the frequency f. Is 0 to 40 kHz.
Moreover, the curve in (A) of FIG. 6 is that the plate | board thickness w of the piping 3 is 30.0 mm, 50.0 mm, 80.0 mm, and 100.0 mm, and the numerical value of the frequency f is 0-20 kHz. Further, the curve in FIG. 6B indicates that the thickness w of the pipe 3 is 0.01 mm, 0.02 mm, 0.03 mm, 0.04 mm, 0.05 mm, and 0.1 mm, and the numerical value of the frequency f. Is 0 to 20 MHz.
As can be seen from FIGS. 5 and 6, the frequency becomes lower as the thickness of the pipe 3 increases.

FIG. 7 shows a curve of propagation velocity-frequency characteristics when the pipe 3 is an iron pipe. The numerical value of the frequency f on the horizontal axis varies depending on the plate thickness w of the pipe 3. The propagation speed is m / s, and the frequency f has a unit of kHz or MHz.
The curves are shown in the case where the plate thickness w of the pipe 3 is 3.0 mm and 5.8 mm, and the numerical value of the frequency f is 0 to 300 kHz. As can be seen from FIG. 7, the frequency decreases as the thickness of the pipe 3 increases.

Next, the velocity dispersion characteristic of the Lamb wave will be described with reference to FIG.
A wave that travels through a plate of finite thickness is called a plate wave or Lamb wave. Lamb waves have a symmetric mode and an anti-symmetric mode (asymmetric mode), and are also simply referred to as S mode and A mode. The Lamb wave is a dispersive wave, and its phase velocity c changes depending on the product fw of the frequency f and the plate thickness w. Therefore, as an example of the Lamb wave, the Lamb wave phase velocity in the aluminum plate is shown in FIG. In FIG. 8, the horizontal axis represents the product value (MHz · mm) of the frequency f and the plate thickness w of the pipe 3, and the vertical axis represents the Lamb wave phase velocity c (m / s). In the figure, Cl represents the longitudinal wave sound velocity in aluminum, Cs represents the transverse wave sound velocity in aluminum, and CR represents the surface wave sound velocity in aluminum. As can be seen from FIG. 8, as the value of f · w increases, many modes can propagate, but the phase velocity c in the A0 mode and the S0 mode approaches the surface wave sound velocity CR, and other modes. It can be seen that approaches the shear wave velocity Cs.

  The pipe thickness measuring apparatus according to the present invention measures the thickness of pipes over the entire area of, for example, steam pipes of nuclear power plants, thermal power plants, etc., pipes of chemical plants, gas pipes, water pipes, etc. Suitable for

It is a block diagram which shows roughly one Example of the piping board thickness measuring apparatus by this invention. It is a graph which shows the propagation velocity-frequency characteristic in the display part of this piping board thickness measuring apparatus. It is an example of the piping material physical property database used for this piping board thickness measuring apparatus, Comprising: It is a graph which shows the propagation speed-frequency characteristic in case the board material of piping is iron. This is another example of the piping material physical property database used for this pipe thickness measuring device, showing the propagation velocity-frequency characteristics when the pipe plate material is iron, and the value of the plate thickness is different from FIG. It is a graph of. It is a further example of the piping material physical property database used for this piping board thickness measuring apparatus, Comprising: It is a graph which shows the propagation speed-frequency characteristic in case the board material of piping is aluminum. It is another example of the piping material physical property database used for this pipe plate thickness measuring device, showing the propagation velocity-frequency characteristics when the pipe plate material is aluminum, and the plate thickness value is different from FIG. It is a graph of. It is a further example of the piping material physical property database used for this piping board thickness measuring apparatus, Comprising: It is a graph which shows the propagation speed-frequency characteristic in case the board material of piping is an iron pipe. It is a graph which shows the velocity dispersion characteristic which shows the phase velocity with respect to the product of the frequency of the Lamb wave in an aluminum plate, and board thickness about this piping board thickness measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Signal input sensor 2 Detection sensor 3 Piping 4 Signal generation circuit 5 Input part 6 Piping material physical property database 7 Measurement analysis part 8 Amplifier 9 Input frequency component extraction filter 10 Display part 11 Memory

Claims (15)

One signal input sensor for inputting an input signal by ultrasonic waves arbitrarily set in advance to the pipe, and one or more for detecting a Lamb wave generated in response to the input signal of the signal input sensor The pipe thickness of the pipe is measured by obtaining a propagation speed between sensors of a specific frequency mechanical vibration between the signal input sensor and the detection sensor based on the propagation speed dispersion of the Lamb wave. A pipe thickness measuring device consisting of: The signal input sensor inputs one or more frequencies of the input signal, the distance between the signal input sensor and the detection sensor, the material of a plate member such as a pipe, and various setting conditions. A function of displaying the plate thickness with respect to the frequency of the input signal and the average value thereof as individual numerical values or plotting them on the characteristics of the propagation speed of the Lamb wave and the frequency The pipe plate thickness measuring device according to claim 1, comprising: 3. The input signal according to claim 1, wherein the input signal is a signal composed of a single frequency component within a range of 100 Hz to 20 MHz, which varies according to the thickness of the pipe. Pipe thickness measuring device. The piping according to any one of claims 1 to 3, wherein the frequency of the input signal is used in a range of an A0 mode not including an Al mode or higher which is the lowest-order antisymmetric mode of the Lamb wave. Plate thickness measuring device. 5. The input signal has a function capable of selecting and inputting only one signal composed of the single frequency component or a plurality of different frequency components. The pipe plate thickness measuring device described in 1. The signal input sensor and the detection sensor induce the Lamb wave in the A0 mode in the measurement object regardless of contact or non-contact with the plate member of the pipe, which is the measurement object, and output the detection signal. The pipe plate thickness measuring device according to any one of claims 1 to 5, wherein an apparatus that can be obtained is used. The pipe thickness measuring device according to any one of claims 1 to 6, wherein the detection signal from the detection sensor is amplified by an amplifier and has a filter function for extracting only the same frequency component as the input signal. . The piping according to any one of claims 1 to 7, wherein the input signal and the detection signal have a function of averaging a plurality of times to improve S / N of the input signal and the detection signal. Plate thickness measuring device. The pipe plate thickness measuring device according to any one of claims 1 to 8, comprising measuring a propagation time Δt from an input signal oscillation to a detection signal arrival. The distance between the signal input sensor and the detection sensor is a length L that can be arbitrarily set, and the signal is input to the signal input sensor as the length L. Pipe thickness measuring device. The pipe plate thickness measuring device according to claim 10, further comprising a function of obtaining a propagation velocity vf for the input signal from the propagation time Δt and the length L. The pipe plate thickness measuring device according to claim 11, which has a function of plotting a characteristic of a relationship between the propagation speed and the frequency as the display of the propagation speed vf. 13. The apparatus according to claim 1, further comprising a database of theoretical velocity dispersion characteristics of the A0 mode, which is a non-target mode of the Lamb wave of the material, and has a function of inputting a material of the pipe. The pipe plate thickness measuring device described in 1. 14. The plate thickness data of the pipe has a function of displaying the data on a display unit and transmitting the data to a remote place by wireless or wired display. Pipe thickness measuring device. The pipe plate thickness according to any one of claims 1 to 14, further comprising a memory for storing the data of the plate thickness of the pipe, and having a function of displaying results measured at different sensor positions together. measuring device.

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