Ultrasonic inspection method and ultrasonic inspection apparatus

Abstract

To provide an ultrasonic inspection method and an ultrasonic inspection device which enable detection of thinning or defects occurring between vertical probes and evaluation of their dimensions.SOLUTION: An ultrasonic inspection method includes the steps of: receiving ultrasonic waves transmitted from a transmission ultrasonic probe 11 and propagating by repeatedly reflecting on an inner surface and a surface of an inspection object 2 using a receiving ultrasonic probe 12; converting the waveform of the received ultrasonic wave into a frequency domain; extracting a feature amount indicating the periodicity in the converted frequency domain; and evaluating the dimension of thinning 3 or defect of the inspection object 2 by using the change amount from a sound state of the feature amount.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an ultrasonic inspection method and an ultrasonic inspection apparatus for measuring, from the outside, wall thinning or defects occurring in an object to be inspected such as piping used in a nuclear power plant, a thermal power plant, a chemical plant, etc. using ultrasonic waves.

Background Art

[0002] Even when wall thinning of a pipe progresses and the wave height of the received ultrasonic wave attenuates, the time difference between reflection pulses is accurately measured, and from this, the current wall thickness, and thus the wall thinning amount, can be measured using a known ultrasonic propagation speed in the pipe material. As an example of a method and apparatus for measuring pipe wall thinning, Patent Document 1 discloses that an ultrasonic pulse is incident from outside the pipe, and after a certain period of time, a reflection pulse is received. The vibration period T appearing in the autocorrelation function φ(τ) of the envelope signal of this reflection pulse is obtained, and the pipe wall thickness d is calculated as d = vT / 2 using the ultrasonic propagation speed v in the pipe material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a nuclear power plant, a thermal power plant, etc., for example, wall thinning due to erosion-corrosion such as impact corrosion may occur at the bent portion of a pipe through which high-temperature and high-flow-rate steam, etc. flows, which is known to be a problem in equipment maintenance.

[0005] Therefore, a non-destructive inspection method has been developed in which, when ultrasonic pulses are incident from outside the pipe using an ultrasonic probe, the reflected waves from the inner surface of the pipe wall are received, and the wall thickness is measured from the time differences between a plurality of reflected pulses generated by repeated reflections between the inner and outer walls of the pipe.

[0006] In the conventional method, a vertical probe was used for pipe wall thickness measurement. Since the inspection area of the vertical probe is directly below the probe, it was possible to measure and detect wall thinning or defects directly below the probe.

[0007] On the other hand, there is a problem that local wall thinning occurring between vertical probes, such as local wall thinning due to droplet impact erosion, cannot be detected. In particular, when a through-hole is generated in the pipe due to local wall thinning, there is a possibility that the plant has to be stopped unexpectedly. Therefore, a method for detecting local wall thinning is required.

[0008] Furthermore, in order to improve the operating rate of the plant, a technique for monitoring the progress rate of local wall thinning as well as detecting local wall thinning is required. The wall thinning monitoring technique requires not only detection of the presence or absence of wall thinning, but also dimensional information such as the depth and width of the detected wall thinning. By monitoring the progress rate and the like from the dimensional information of the wall thinning, it is possible to improve the operating rate by planned pipe replacement, improvement of plant reliability, and rationalization of maintenance.

[0009] As one such technique, there is, for example, a technique described in Patent Document 1. In this Patent Document 1, even when the wall thinning of the pipe progresses and the wave height of the received ultrasonic wave attenuates, the time difference between the reflected pulses can be accurately measured, and from this, the current wall thickness, and thus the wall thinning amount, can be measured using the known ultrasonic propagation speed in the pipe material.

[0010] However, the technique of Patent Document 1 is a method for evaluating the wall thinning depth of a pipe with advanced wall thinning, and has a problem that the wall thinning width cannot be evaluated. Also, it can only evaluate the wall thinning directly below where the vertical probe is placed.

[0011] Here, it is also known to evaluate the thinning that occurs between ultrasonic probes by using a plurality of vertical probes. In this inspection method, an ultrasonic wave is multiply reflected inside the pipe using an angled ultrasonic probe, and the presence or absence of thinning is evaluated from the change in the reflected waveform.

[0012] However, in order to evaluate the thinning dimension, it is necessary to separate the reflection component from the pipe bottom surface and the reflection component derived from thinning from the reflected waveform. However, since the reflection components overlap, separation is difficult, and there is a problem that it is difficult to evaluate the dimensions of thinning and defects.

[0013] Therefore, an object of the present invention is to provide an ultrasonic inspection method and an ultrasonic inspection apparatus capable of detecting thinning or defects that occur between vertical probes and evaluating their dimensions.

Means for Solving the Problems

[0014] The present invention includes a plurality of means for solving the above problems. For example, an ultrasonic wave transmitted from a transmitting ultrasonic probe and repeatedly reflected on the inner surface and the outer surface of the inspection object is received using a receiving ultrasonic probe, and the waveform of the received ultrasonic wave is converted into the frequency domain. In the converted frequency domain, a feature amount indicating periodicity is extracted, and the dimension of the thinning or defect of the inspection object is evaluated using the amount of change from the normal state of the feature amount. and, in the evaluating step, cepstrum analysis processing is performed on the received ultrasonic waveform, and the depth of the meat reduction or defect is evaluated from the period interval of the result of the cepstrum analysis processing, and the width of the meat reduction or the defect is evaluated from the period intensity of the result of the cepstrum analysis processing It is characterized by that.

Effects of the Invention

[0015] According to the present invention, it is possible to detect thinning or defects that occur between vertical probes and evaluate their dimensions. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

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Figure 5

Figure 6

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Figure 8

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Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the ultrasonic inspection method and ultrasonic inspection apparatus of the present invention will be described with reference to the drawings.

[0018] In the drawings used in this specification, the same or corresponding components are denoted by the same or similar reference numerals, and repeated descriptions of these components may be omitted.

[0019] In the following examples, a pipe wall thickness reduction inspection apparatus for inspecting pipe wall thickness reduction and defects is shown as an example of the inspection method and inspection apparatus, but the inspection method and inspection apparatus of the present invention are not limited thereto and can be applied to inspections of various structures.

[0020] <Example 1> Example 1 of the ultrasonic inspection method and ultrasonic inspection apparatus of the present invention will be described with reference to FIGS. 1 to 7.

[0021] First, the overall configuration of the ultrasonic inspection apparatus will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing the configuration of the ultrasonic inspection apparatus in Example 1, and FIG. 2 is a diagram showing a usage example of the ultrasonic inspection apparatus in Example 1.

[0022] The ultrasonic inspection apparatus 1 shown in FIG. 1 includes a transmitting ultrasonic probe 11, a receiving ultrasonic probe 12, a pulsar 13, a receiver 14, a control unit 15, a data recording unit 16, a signal processing unit 17, and a display unit 18.

[0023] Among these, the processing unit 10 composed of the pulsar 13, the receiver 14, the control unit 15, the data recording unit 16, the signal processing unit 17, and the display unit 18 can be configured by a computer having a display unit 18 such as a liquid crystal display described later, an input device, a storage device that also serves as the data recording unit 16, a CPU, a memory, etc. It may be configured by one computer or by another computer, and is not particularly limited.

[0024] The control of the operation in the processing unit 10 is executed based on various programs recorded in the storage device. Note that the control processing of the operation executed by the processing unit 10 may be summarized in one program, may be separated into a plurality of programs respectively, or may be a combination thereof. Also, part or all of the program may be realized by dedicated hardware or may be modularized.

[0025] A vertical probe is used for both the transmitting ultrasonic probe 11 that emits ultrasonic waves and the receiving ultrasonic probe 12 that receives ultrasonic waves, and they are arranged on the surface of the object 2 to be inspected. These transmitting ultrasonic probe 11 and receiving ultrasonic probe 12 can measure by switching the functions of transmitting and receiving between the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12 by the control unit 15 switching the pulsar 13 and the receiver 14. That is, either probe can be used for transmitting ultrasonic waves, and the other can be used for receiving ultrasonic waves that are repeatedly reflected and propagated on the inner and outer surfaces of the object 2 to be inspected.

[0026] The pulsar 13 and the receiver 14 are connected to the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12.

[0027] The control unit 15 is a part that controls the operations of the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12, and corresponds to, for example, a part of the above-mentioned CPU. For example, the control unit 15 outputs an ultrasonic pulse to the transmitting ultrasonic probe 11 via the pulsar 13, and receives the ultrasonic waves that are repeatedly reflected and propagated on the inner and outer surfaces of the object 2 to be inspected as electrical signals via the receiving ultrasonic probe 12 and the receiver 14.

[0028] The data recording unit 16 is, for example, a part that digitizes the electrical signals received by the control unit 15 and records them as data, and is preferably composed of a storage device such as an HDD or an SSD.

[0029] The signal processing unit 17 corresponds to a part of the above-mentioned CPU, and obtains the change over time of the amplitude intensity starting from the output time of the electrical signals digitized by the data recording unit 16. Specifically, the waveform of the received ultrasonic wave is converted into the frequency domain, a feature quantity indicating periodicity is extracted in the converted frequency domain, and the dimension of the metal loss 3 or defect of the object 2 to be inspected is evaluated using the change amount from the sound state of the feature quantity.

[0030] In addition, in this embodiment, the signal processing unit 17 preferably performs cepstrum analysis processing on the received ultrasonic waveform, evaluates the depth of the thinning 3 or the defect from the period interval of the result of the cepstrum analysis processing, and evaluates the width of the thinning 3 or the defect from the period intensity of the result of the cepstrum analysis processing.

[0031] The display unit 18 is the above-described display, and displays the result of evaluating the thinning 3 or the dimension.

[0032] Next, the general operation flow of the ultrasonic inspection apparatus 1 of this embodiment will be described.

[0033] First, a transmission command for the ultrasonic pulse 4 is output from the control unit 15 to the transmitting ultrasonic probe 11 via the pulsar 13. In response to the transmission command, ultrasonic waves are transmitted from the transmitting ultrasonic probe 11, and the transmitted ultrasonic pulse reaches the receiving ultrasonic probe 12 as a multiple reflection wave that repeats reflection on the inner wall back surface of the inspection object 2, and receives an electrical signal as a received signal via the receiver 14.

[0034] The received signal is digitized by the data recording unit 16 and recorded as data. This data shows the change over time of the amplitude intensity of the electrical signal starting from the output time of the pulse signal, as shown in FIG. 3.

[0035] The data obtained by the data recording unit 16 is processed by the signal processing unit 17, and the result of evaluating the dimension of the thinning 3 is displayed on the display unit 18.

[0036] When there is a thinning 3 or a defect in the waveguide propagation path of the multiply reflected ultrasonic wave, the waveguide propagation path of the reflected wave 5 changes, appears in the received waveform as a change over time, and the display unit 18 displays the depth and width dimensions of the thinning 3 or the defect via the data recording unit 16 and the signal processing unit 17.

[0037] Here, in the pipe thinning measurement in which the ultrasonic pulse 4 is transmitted and received by one vertical probe, a received waveform as shown in FIG. 4 is obtained. The received waveform in FIG. 4 has a reflection peak X due to the thinning 3 d and a reflection peak X due to the pipe wall thicknessb It is a waveform including [the above], and the reflected peak from the material removal 3 contains information regarding the depth of the material removal 3. From the received waveform of FIG. 4, it is possible to distinguish the reflected peak from the material removal 3 and the reflected peak from the pipe wall thickness. However, there is a problem that the information on the width of the material removal 3 cannot be obtained and dimensional evaluation cannot be performed.

[0038] On the other hand, the received waveform of FIG. 3 is a reflected wave that has undergone multiple reflections inside the pipe between the probes. Although the received waveform of FIG. 3 also contains width information, since the reflected peak from the pipe and the reflected peak from the material removal 3 are complexly superimposed, it is difficult to distinguish the two different reflected peaks. Therefore, a process of extracting the reflected peak from the material removal 3 from the reflected peak from the pipe wall thickness is necessary.

[0039] Therefore, in the ultrasonic inspection of this embodiment, the waveform of the received ultrasonic wave is converted into the frequency domain, and in the converted frequency domain, a feature amount indicating periodicity is extracted. The processing content of this characteristic signal processing unit 17 will be described with reference to FIGS. 5 and 6. FIG. 5 is a flowchart showing the processing content of the signal processing unit in this embodiment. FIG. 6 is the cepstrum analysis result after signal processing.

[0040] The signal processing unit 17 performs signal processing on the data of the data recording unit 16 according to the flowchart of FIG. 5.

[0041] Specifically, preferably, cepstrum analysis is used as a method for evaluating the depth and width dimensions of the material removal 3 or the defect.

[0042] This cepstrum analysis is a signal processing for extracting periodic characteristics from the received waveform or received signal, and is effective for a waveform or signal in which a plurality of overlapping periods that cannot be extracted by Fourier transform or the like are present, and since the periodic characteristics of only the target sound signal can be extracted from the sound signal including ambient noise by cepstrum analysis, it is utilized in the acoustic field and the like.

[0043] Therefore, in the thinning inspection of the object to be inspected 2 such as a pipe, by extracting the periodic characteristics derived from the thinning 3 from the received waveform, it becomes possible to evaluate the depth and width dimension information of the thinning 3 from the periodic characteristics. Hereinafter, the procedure of cepstrum analysis using the received waveform is shown below.

[0044] First, the received waveform will be described with reference to FIG. 3. In the received waveform obtained by multiple reflections between the probes in FIG. 3, the reflection peak derived from the thinning 3 contains information regarding the width of the thinning 3 in addition to the information regarding the depth of the thinning 3. However, since the reflection peak derived from the thinning 3 overlaps with the reflection peak derived from the pipe wall thickness, it is difficult to directly evaluate the dimensions of the thinning 3 from the received waveform.

[0045] Therefore, calculations are performed on the received waveform including the reflection peak as a feature quantity indicating periodicity according to the procedure in FIG. 5 to extract information regarding the dimensions of the thinning 3.

[0046] Specifically, as shown in FIG. 5, the signal processing unit 17 converts the received waveform (step S101) input from the data recording unit 16 into a frequency spectrum by Fourier transform processing (step S102).

[0047] Next, the signal processing unit 17 converts the frequency spectrum into a logarithmic spectrum by logarithmic processing (step S103), and finally performs an inverse Fourier transform (step S104) to obtain the cepstrum analysis result.

[0048] Finally, the signal processing unit 17 performs dimension evaluation of the thinning 3 based on the obtained cepstrum analysis result (step S105), and outputs the evaluation result to the display unit 18. As a result, the evaluation result is displayed on the display unit 18.

[0049] The screen displayed at this time can be, for example, a cepstrum showing the periodic intensity with respect to the periodic interval as shown in FIG. 6, but is not limited thereto, and can be either the specific numerical values of the dimensions of the thinning 3 or the defect extracted from the cepstrum in FIG. 6, or both the cepstrum in FIG. 6 and the specific numerical values of the dimensions of the thinning 3 or the defect extracted therefrom.

[0050] Next, the reduction dimension evaluation will be described with reference to FIG. 6. The horizontal axis in FIG. 6 is called the period interval (Kefrenci) and represents the time pitch of the reflection peaks of the received waveform, and the vertical axis is the period intensity derived from the amplitude intensity of the received waveform.

[0051] In FIG. 6, the period interval value on the horizontal axis at the peak value of the period intensity on the vertical axis represents the received waveform from the reduction of 3 and the received waveform from the pipe wall thickness, respectively. Since the value indicated by the period interval is the same as the propagation distance of the ultrasonic wave, it can be separated into the period interval from the pipe wall thickness and the period interval from the reduction of 3, and the reduction of 3 or the depth of the defect and the pipe wall thickness can be compared and evaluated.

[0052] The reduction of 3 or the depth of the defect can be calculated if the sound velocity of the material to be inspected is known. For example, for the case where the material to be inspected is carbon steel, an example of calculating the pipe wall thickness and the depth of the reduction of 3 will be described with reference to FIG. 6.

[0053] The pipe wall thickness is obtained from the product of the sound velocity of carbon steel (5900 m / s) and the period interval from the pipe wall thickness (2.0 μs). Specifically, the sound velocity of 5900 m / s × the period interval (2.0 × 10 -6 m) = 11.8 mm is obtained. This value is the propagation path from the transmitting ultrasonic probe 11 to the receiving ultrasonic probe 12 and corresponds to twice the distance of the pipe wall thickness. Therefore, the pipe wall thickness can be calculated as 11.8 m / 2 = 5.9 mm.

[0054] The reduction of 3 or the defect depth can be calculated in the same way as follows. Assuming the period interval value from the reduction of 3 or the defect is 1.0 μs, from the propagation path of the sound velocity of 5900 m / s × the period interval of the reduction of 3 (1.0 × 10 -6 m) = 5.9 mm, the pipe wall thickness of 5.9 mm / 2 = 2.95 mm is obtained. From the difference between the initial wall thickness of 5.9 mm and the wall thickness of 2.95 mm at the time of the occurrence of the reduction of 3, the depth of the reduction of 3 can be evaluated as 2.95 mm.

[0055] Furthermore, the peak intensity of the periodic intensity derived from the 3rd thinning increases as the width of the 3rd thinning increases, and the peak intensity of the periodic intensity derived from the pipe wall thickness decreases relatively with respect to the peak intensity derived from the 3rd thinning. As shown in Fig. 7, the reduction rate of the peak intensity of the pipe wall thickness periodic intensity is correlated with the width of the 3rd thinning or the defect and the distance between the probes.

[0056] From these relationships, if the distance between the probes is clear, it can be seen that in addition to the depth of the 3rd thinning or the defect, its width can also be evaluated, and the dimensions (depth and width) can be evaluated. Usually, since the distance between the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12 is known, the dimensions of the 3rd thinning or the defect are obtained.

[0057] Next, the effects of this embodiment will be described.

[0058] The ultrasonic inspection method of Example 1 of the present invention described above includes a step of transmitting ultrasonic waves from the transmitting ultrasonic probe 11 and receiving, using the receiving ultrasonic probe 12, the ultrasonic waves that are repeatedly reflected and propagated on the inner and outer surfaces of the inspection object 2, and a step of converting the waveform of the received ultrasonic waves into the frequency domain, extracting a feature amount indicating periodicity in the converted frequency domain, and evaluating the dimensions of the 3rd thinning or the defect of the inspection object 2 using the amount of change from the sound state of the feature amount.

[0059] Therefore, it is possible to detect the 3rd thinning or the defect generated between the vertical probes and evaluate its dimensions.

[0060] Also, in the evaluation step, cepstrum analysis processing is performed on the waveform of the received ultrasonic waves, the depth of the 3rd thinning or the defect is evaluated from the period interval of the result of the cepstrum analysis processing, and the width of the 3rd thinning or the defect is evaluated from the periodic intensity of the result of the cepstrum analysis processing. As a result, the reflected wave derived from the pipe wall thickness and the reflected wave derived from the 3rd thinning can be separated from the received signal with high accuracy, so that the 3rd thinning or the defect width can be evaluated more accurately.

[0061] <Example 2> The ultrasonic inspection method and ultrasonic inspection apparatus according to Example 2 of the present invention will be described with reference to FIGS. 8 and 9. FIG. 8 is a diagram showing an example of the installation of a fixed ultrasonic probe in the ultrasonic inspection apparatus according to Example 2, and FIG. 9 is a diagram showing an example of the use of the fixed ultrasonic probe.

[0062] Thinning 3 or defects in piping or the like in a plant are likely to occur at the curved portions of curved pipes or elbow pipes, or at narrow portions of piping or the like where the flow of the fluid inside the pipe changes.

[0063] Therefore, as shown in FIGS. 8 and 9, in the ultrasonic inspection apparatus 1A of the present embodiment, the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12 are permanently installed at the surface locations of the inspection object 2 where thinning 3 or defects are likely to occur, and are constantly monitored during the operation period of the plant.

[0064] By using two or more fixed ultrasonic vertical probes and measuring separately with the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12 as shown in FIG. 9, it is possible to detect thinning 3 or defects between the probes.

[0065] The other configurations and operations are substantially the same as those of the ultrasonic inspection method and ultrasonic inspection apparatus 1 of the aforementioned Example 1, and the details will be omitted.

[0066] In the ultrasonic inspection method and ultrasonic inspection apparatus 1A according to Example 2 of the present invention, substantially the same effects as those of the ultrasonic inspection method and ultrasonic inspection apparatus 1 of the aforementioned Example 1 can be obtained.

[0067] In addition, since the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12 are permanently installed on the surface of the inspection object 2, it is possible to grasp the progress of thinning 3 or defects over time, and it is possible to precisely predict the progress of thinning 3 and the like.

[0068] <Example 3> The ultrasonic inspection method and ultrasonic inspection apparatus according to Embodiment 3 of the present invention will be described with reference to FIGS. 10 and 11. FIG. 10 is a diagram showing an example of probe installation of a wireless ultrasonic probe in the ultrasonic inspection apparatus according to Embodiment 3, and FIG. 11 is a diagram showing an example of use of the wireless ultrasonic probe.

[0069] When the ultrasonic inspection apparatus 1 described in Embodiment 1 is used for pipe wall thinning inspection using ultrasonic waves in a plant, an inspector needs to directly press the transmitting ultrasonic probe 11 and the receiving ultrasonic probe 12 against the pipe surface.

[0070] Here, when the inspection object 2 is at a high place, especially when there is a heat insulating material or the like wound around the inspection object 2, there are many additional operations such as construction of a scaffold for inspection and attachment / detachment of the heat insulating material covering the pipe at the high place, and there is a problem that the inspection time may increase.

[0071] Also, in the case where it is difficult for an inspector to access due to the complexity of pipes or the like, there are many additional operations as well, and there is a concern about an increase in the inspection time.

[0072] Therefore, in order to reduce the above-mentioned additional operations, the ultrasonic inspection apparatus 1B of the present embodiment uses a wireless ultrasonic probe (see FIGS. 10 and 11) as the transmitting ultrasonic probe and the receiving ultrasonic probe.

[0073] As shown in FIGS. 10 and 11, the transmitting wireless ultrasonic probe 21 and the receiving wireless ultrasonic probe 22 are permanently installed on the surface of the inspection object 2 before the heat insulating material 300 is wound, and the heat insulating material 300 is provided thereon.

[0074] Then, at the time of inspection, an instruction for ultrasonic wave transmission to the transmitting wireless ultrasonic probe 21 and a signal of ultrasonic waves that are repeatedly reflected and propagated on the inner surface and the surface of the inspection object 2 received by the receiving wireless ultrasonic probe 22 are transmitted and received non - contact by the wireless probe leader 400, and are analyzed and processed in the processing unit 10 in the same manner as in Embodiment 1.

[0075] Also, similar to Embodiments 1 and 2, by using two or more wireless ultrasonic probes and measuring separately with a transmitting wireless ultrasonic probe 21 and a receiving wireless ultrasonic probe 22 as shown in FIG. 11, it is possible to detect the thinning or defects between the probes.

[0076] The other configurations and operations are substantially the same as those of the ultrasonic inspection method and the ultrasonic inspection apparatus 1 of Embodiment 1 described above, and the details are omitted.

[0077] In the ultrasonic inspection method and the ultrasonic inspection apparatus 1B of Embodiment 3 of the present invention, substantially the same effects as those of the ultrasonic inspection method and the ultrasonic inspection apparatus 1 of Embodiment 1 described above can be obtained.

[0078] In addition, by using a transmitting ultrasonic probe and a receiving ultrasonic probe as wireless ultrasonic probes, additional operations such as removing the heat insulating material 300 can be reduced, and the inspection burden can be further reduced.

[0079] <Others> Note that the present invention is not limited to the above embodiments, and various modifications are included. The above embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.

[0080] Also, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Also, it is possible to add, delete, or replace other configurations for a part of the configuration of each embodiment.

Explanation of Reference Numerals

[0081] 1, 1A, 1B... Ultrasonic inspection apparatus 2... Object to be inspected 3... Thinning or defect 4... Ultrasonic pulse 5... Reflected wave 10... Processing unit 11... Transmitting ultrasonic probe 12… Credit ultrasonic probe 13… Pulser 14… Receiver 15… Control unit 16… Data recording unit 17… Signal processing unit 18… Display unit 21… Transmitting wireless ultrasonic probe 22… Receiving wireless ultrasonic probe 300… Heat insulating material 400… Wireless probe reader X d … Reflection peak from meat reduction X b … Reflection peak from pipe wall thickness

Claims

1. A step of transmitting ultrasonic waves from a transmitting ultrasonic probe and receiving the ultrasonic waves that are repeatedly reflected and propagated on the inner and outer surfaces of the object to be inspected using a receiving ultrasonic probe; A step of converting the waveform of the received ultrasonic waves into a frequency domain, extracting a feature amount indicating periodicity in the converted frequency domain, and evaluating the dimensions of the wall thinning or defect of the object to be inspected using the amount of change from the normal state of the feature amount; and having, In the step of evaluating, cepstrum analysis processing is performed on the waveform of the received ultrasonic waves, and the depth of the wall thinning or the defect is determined from the period interval of the result of the cepstrum analysis processing, and the wall thinning or the defect is determined from the period intensity of the result of the cepstrum analysis processing. Evaluate the width of An ultrasonic inspection method characterized by the above.

2. A transmitting ultrasonic probe that transmits ultrasonic waves; A receiving ultrasonic probe that receives ultrasonic waves that are transmitted from the transmitting ultrasonic probe and are repeatedly reflected and propagated on the inner and outer surfaces of the object to be inspected; A pulsar and a receiver connected to the transmitting ultrasonic probe and the receiving ultrasonic probe; A control unit that controls the operations of the transmitting ultrasonic probe and the receiving ultrasonic probe; A signal processing unit; Comprising, The signal processing unit performs cepstrum analysis processing on the waveform of the received ultrasonic waves, evaluates the depth of wall thinning or defect from the period interval of the result of the cepstrum analysis processing, and evaluates the wall thinning or the defect from the period intensity of the result of the cepstrum analysis processing. Evaluate the width of An ultrasonic inspection apparatus characterized by the above.

3. In the ultrasonic inspection apparatus according to claim 2, The control unit outputs an ultrasonic pulse to the transmitting ultrasonic probe via the pulsar, and receives, as an electrical signal, ultrasonic waves that are repeatedly reflected and propagated on the inner and outer surfaces of the object to be inspected via the receiving ultrasonic probe and the receiver. A data recording unit that digitizes the electrical signal received by the control unit and records it as data; A display unit that displays the results of evaluating the depths and widths of the wall thinning or the defects; An ultrasonic inspection apparatus characterized by having the above.

4. In the ultrasonic inspection apparatus according to claim 2, The transmitting ultrasonic probe and the receiving ultrasonic probe are permanently installed on the surface of the object to be inspected An ultrasonic inspection apparatus characterized by the above.

5. In the ultrasonic inspection apparatus according to claim 2, The ultrasonic probe for transmission and the ultrasonic probe for reception are wireless ultrasonic probes. An ultrasonic inspection apparatus characterized by this.

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