Inspection device and inspection method

Abstract

To provide an inspection device and an inspection method that can two-dimensionally detect the range of wall thinning.SOLUTION: An inspection device 1 includes a probe group 100, an ultrasonic waveform recording unit 125 (recording unit), and a calculation unit 127. The probe group 100 has a plurality of vertical probes 101 that are attached perpendicular to the surface of an object to be inspected and transmit and receive ultrasonic waves. The ultrasonic waveform recording unit 125 records multiple received signals obtained by receiving ultrasonic waves transmitted from a first probe with a plurality of probes other than the first probe. The calculation unit 127 calculates multiple attenuation indices that represent the degree of attenuation of multiple second received signals received after the multiple first received signals relative to multiple first received signals recorded before wall thinning occurred in the object to be inspected among the multiple received signals. The calculation unit 127 then detects the range of wall thinning based on the multiple attenuation indices.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inspection device and an inspection method for inspecting whether or not there is wall thinning occurring in a structure such as a pipe. [Background technology]

[0002] Conventionally, ultrasonic crack detection and wall thickness inspection have been performed during periodic inspections at nuclear power plants, thermal power plants, etc. Non-destructive testing using ultrasonic waves can check for deterioration of an object while the object is still in place. Therefore, non-destructive testing using ultrasonic waves is used in a wide range of fields because it is inexpensive and easy to apply.

[0003] Patent Document 1 describes an inspection device and an inspection method that enable inspection of structures such as pipes for wall thinning and defects. The inspection device described in Patent Document 1 includes a plurality of probes that are attached perpendicularly to the surface of the object to be inspected and transmit and receive ultrasonic waves, signal lines, and a signal processor.

[0004] When transmitting ultrasonic waves perpendicular to the inner surface of the object under test, the probe emits ultrasonic waves in a cone shape in a direction different from the perpendicular direction. The ultrasonic waves emitted perpendicularly are reflected by the inner surface of the object under test and received by the transmitting probe. The ultrasonic waves emitted in a direction different from the perpendicular direction propagate, repeatedly reflecting off the inner surface and surface of the object under test, and are received by another probe adjacent to the probe that emitted the ultrasonic waves.

[0005] The signal processor analyzes and processes ultrasonic waves emitted in the perpendicular direction and reflected from the probe, as well as ultrasonic waves emitted in directions other than the perpendicular direction and reflected from the probe. This allows the inspection device described in Patent Document 1 to inspect for thinning or defects in positions other than directly below the probe. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2022-163592 Summary of the Invention [Problem to be solved by the invention]

[0007] Meanwhile, pipe wall thinning that occurs often has a two-dimensional spread across multiple probes arranged in a grid pattern, as disclosed in Patent Document 1. In recent years, there has been a demand for grasping the two-dimensional spread of wall thinning in wall thinning inspections. However, while the inspection device described in Patent Document 1 can grasp the presence or absence of wall thinning and the thickness between adjacent probes, it cannot grasp the two-dimensional spread of wall thinning.

[0008] In consideration of the above problems, the present invention aims to provide an inspection device and an inspection method that can two-dimensionally detect the extent of wall thinning. [Means for solving the problem]

[0009] To solve the above problems and achieve the object, an inspection device embodying one aspect of the present invention performs non-destructive inspection of an object to be inspected and includes a probe group, a recording unit, and a calculation unit. The probe group has multiple probes attached perpendicularly to the surface of the object to be inspected and transmit and receive ultrasonic waves. The recording unit records multiple received signals obtained by receiving ultrasonic waves transmitted from a first probe included in the probe group with multiple probes other than the first probe. The calculation unit calculates multiple attenuation indices that represent the degree of attenuation of multiple second received signals received after the multiple first received signals relative to multiple first received signals recorded before thinning occurred in the object to be inspected. The calculation unit then detects the extent of thinning based on the multiple attenuation indices.

[0010] An inspection method embodying one aspect of the present invention is a method for nondestructively inspecting an object using received signals acquired from a probe group having multiple probes attached perpendicular to the surface of the object and transmitting and receiving ultrasonic waves. In this inspection method, first, a recording unit records multiple received signals obtained by receiving ultrasonic waves transmitted from a first probe included in the probe group with multiple probes other than the first probe. Next, a calculation unit calculates multiple attenuation indices that represent the degree of attenuation of multiple second received signals received after the multiple first received signals, relative to the multiple first received signals recorded before the object was thinned. Then, the calculation unit detects the extent of thinning based on the multiple attenuation indices. [Effects of the Invention]

[0011] According to the inspection device and inspection method configured as described above, the range of wall thinning can be detected two-dimensionally. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing the overall configuration of an inspection device according to a first embodiment. [Figure 2] 1 is a block diagram showing the functions of an ultrasonic transmitting and receiving device according to a first embodiment. [Figure 3] FIG. 3 is a diagram showing the sound wave intensity distribution of the probe according to the first embodiment. [Figure 4] 3 is a diagram showing the propagation of ultrasonic waves when a plurality of probes of the inspection device according to the first embodiment are attached to a pipe. FIG. [Figure 5] 10A and 10B are diagrams illustrating propagation of ultrasonic waves emitted from a plurality of probes when thinning occurs in a pipe. [Figure 6] FIG. 1A is a diagram showing an ultrasonic waveform received when no thinning occurs, and FIG. 1B is a diagram showing an ultrasonic waveform received when thinning occurs. [Figure 7] 4 is a flowchart showing an example of a wall-thickness reduction inspection procedure according to the first embodiment. [Figure 8] 5 is a flowchart showing an example of a wall-thinning distribution measurement process according to the first embodiment. [Figure 9] FIG. 10 is a diagram showing the positions of a plurality of probes arranged in a grid pattern on a pipe. [Figure 10] FIG. 10 is a diagram showing the positions of the multiple probes shown in FIG. 9 in a plane coordinate system. [Figure 11] 11 is a diagram showing the results of plotting values ​​of attenuation rates on a line connecting the positions of two probes for all combinations of the positions of two probes in the plane coordinate system shown in FIG. 10. FIG. [Figure 12] FIG. 12 is a diagram showing a state in which a thinning range is extracted from the state shown in FIG. 11. [Figure 13] FIG. 13 is a diagram showing a state in which the state shown in FIG. 12 is transformed into a three-dimensional coordinate system. [Figure 14] 10A and 10B are diagrams illustrating the propagation of ultrasonic waves emitted from a probe when an elliptical thinning occurs in a pipe. [Figure 15] 10A and 10B are diagrams illustrating the propagation of ultrasonic waves emitted from a probe when a slit-shaped thinning occurs in a pipe. [Figure 16] 10 is a graph showing the relationship between the attenuation rate and the depth of wall thinning according to the shape of wall thinning. [Figure 17] FIG. 10 is a diagram showing the results of plotting values ​​of attenuation rates on a line connecting the positions of two probes for all combinations of the positions of two probes within a measurement range according to the second embodiment. [Figure 18] 10A and 10B are diagrams illustrating an example in which ultrasonic waveform signals are measured at all positions of a plurality of probes by shifting the measurement range according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] An inspection device and an inspection method according to an embodiment will be described below with reference to Figures 1 to 18. In the drawings used in this specification, identical or corresponding components are denoted by the same or similar reference numerals, and repeated description of these components may be omitted.

[0014] In the following embodiments, an inspection device for inspecting pipes for thinning and defects is shown as an example, but the inspection device and inspection method of the present invention are not limited to this and can be applied to the inspection of a wide variety of structures.

[0015] 1. First embodiment [Inspection equipment configuration] First, the configuration of the inspection device according to the first embodiment will be described with reference to FIGS. Fig. 1 is a schematic diagram showing the overall configuration of an inspection device according to a first embodiment, and Fig. 2 is a diagram showing the propagation of ultrasonic waves when a plurality of probes of the inspection device according to the first embodiment are attached to a pipe.

[0016] The inspection device 1 shown in Fig. 1 is an apparatus used for non-destructive inspection of a pipe 200 installed in a plant. The inspection device 1 is used to inspect the pipe 200 for the presence or absence of wall thinning and defects. Note that a defect in the pipe 200 is, for example, a crack or fissure occurring in the pipe 200. In this embodiment, defects such as cracks or fissures may be described as part of wall thinning.

[0017] As shown in Fig. 1, the inspection device 1 includes a probe group 100 attached to the outer surface of a pipe 200, and an ultrasonic transmitting / receiving device 120. Fig. 1 shows an elbow portion of the pipe 200, which is a portion where thinning is particularly likely to occur. Note that the location where the probe group 100 is attached is not limited to a curved elbow portion, and may be a straight pipe portion.

[0018] The probe group 100 is composed of a plurality of vertical probes 101. The plurality of vertical probes 101 are arranged in a grid pattern. The arrangement of the plurality of vertical probes 101 is not limited to a grid pattern, and may be, for example, a staggered pattern or an irregular arrangement. The number of vertical probes 101 is determined depending on the size of the area to be inspected in the pipe 200 and the structure of the pipe 200.

[0019] Guidelines for the placement of multiple vertical probes are found, for example, in the "Japan Society of Mechanical Engineers, Nuclear Power Plant Equipment Standards for Power Generation, Boiling Water Nuclear Power Plant, Technical Standards for Pipe Thinning Management (2006 Edition)." This standard specifies that the measurement pitch for pipes with diameters of 125A or less must be four or more points circumferentially, and the measurement length of the downstream straight pipe section for pipes with diameters of 125A or less must be the smaller of 2D (D is the pipe diameter) or 100mm axially. Furthermore, for pipes with diameters greater than 125A, the measurement pitch must be eight or more points circumferentially, and the measurement length of the downstream straight pipe section for pipes with diameters greater than 125A must be 100mm axially.

[0020] The dimensions of the grid in this embodiment can be set to, for example, 50 mm wide, thereby satisfying the above-mentioned standards. The arrangement of the multiple vertical probes 101 can be determined appropriately depending on the standards of various inspection objects and the range of wall thinning to be detected.

[0021] The multiple vertical probes 101 are fixed to the pipe 200 in an orientation in which the portions that transmit and receive ultrasonic waves are approximately perpendicular to the outer surface of the pipe 200. The multiple vertical probes 101 are fixed using, for example, a heat-resistant adhesive that is capable of transmitting sound waves. This allows the multiple vertical probes 101 to be used not only when the plant is stopped but also when the plant is operating.

[0022] The plurality of vertical probes 101 are connected to the ultrasonic transmitting and receiving device 120 via signal lines 140. The signal transmission means between the plurality of vertical probes 101 and the ultrasonic transmitting and receiving device 120 is not limited to wired and may be wireless.

[0023] [Functional configuration of ultrasonic transmitter / receiver] Next, the functional configuration of the ultrasonic transmitting and receiving device 120 will be described with reference to FIG. FIG. 2 is a block diagram showing the functions of the ultrasonic transmitting and receiving device 120. As shown in FIG.

[0024] As shown in FIG. 2, the ultrasonic transmitting / receiving device 120 has a plurality of changeover switches 121, a pulser receiver 122, a multiplexer 123, an amplifier 124, an ultrasonic waveform recording unit 125, a memory unit 126, and a calculation unit 127.

[0025] The multiple changeover switches 121 are connected to the multiple vertical probes 101 via signal lines 140. The changeover switches 121 are double-throw switches. A pulser receiver 122 is connected to one contact of the changeover switch 121, and a multiplexer 123 is connected to the other contact. The multiplexer 123 is connected to an ultrasonic waveform recording unit 125 via an amplifier 124. The ultrasonic waveform recording unit 125 is connected to a storage unit 126 and a calculation unit 127.

[0026] The pulser receiver 122 applies a pulsed voltage to the vertical probe 101 via the changeover switch 121. This causes the vertical probe 101 to emit pulsed ultrasonic waves toward the inner surface of the pipe 200. Note that the voltage applied to the vertical probe 101 is not limited to a pulsed voltage. For example, a sinusoidally varying voltage signal may be applied continuously over time to the probe according to the present invention.

[0027] The multiplexer 123 receives ultrasonic waveform signals sent from the multiple vertical probes 101 and outputs them to the amplifiers 124. The ultrasonic waveform signals correspond to the received signals according to the present invention. The amplifiers 124 amplify the ultrasonic waveform signals sent from the multiplexer 123 and output them to the ultrasonic waveform recording unit 125.

[0028] The ultrasonic waveform recording unit 125 records the ultrasonic waveform signal amplified by the amplifier 124. The storage unit 126 stores the ultrasonic waveform signal recorded by the ultrasonic waveform recording unit 125. The calculation unit 127 calculates the attenuation rate of the ultrasonic waveform signal. Furthermore, the calculation unit 127 detects the extent of wall thinning based on the calculated attenuation rate. The attenuation rate is an attenuation index that indicates the degree of attenuation of the ultrasonic waveform signal.

[0029] [Propagation of ultrasonic waves emitted from a vertical transducer] Next, propagation of the ultrasonic waves emitted from the vertical probe 101 will be described with reference to FIGS. Fig. 3 is a diagram showing the sound wave intensity distribution of the vertical probe 101. Fig. 4 is a diagram showing the propagation of ultrasonic waves when multiple vertical probes 101 are attached to the pipe 200. Fig. 5 is a diagram showing the propagation of ultrasonic waves emitted from multiple vertical probes 101 when thinning occurs in the pipe 200. Fig. 6 is a diagram showing the waveforms of received signals when thinning does not occur and when thinning occurs.

[0030] In Fig. 3, lighter colored areas indicate greater ultrasonic intensity, and darker colored areas indicate less intense ultrasonic waves. As shown in Fig. 3, ultrasonic waves emitted from the vertical probe 101 travel in both a straight-down direction and a diagonally downward direction. The intensity of ultrasonic waves traveling in a straight-down direction is greater than the intensity of ultrasonic waves traveling in a diagonally downward direction. Note that ultrasonic waves traveling in a diagonally downward direction have components at a continuous range of angles.

[0031] 4, ultrasonic waves 111 emitted from a vertical probe 101a attached to a pipe 200 and traveling directly downward are reflected by the inner surface of the pipe 200 and received by the vertical probe 101a. On the other hand, ultrasonic waves 112 emitted from the vertical probe 101a and traveling diagonally downward are propagated after multiple reflections on the inner surface of the pipe 200. Then, the ultrasonic waves 112 are received by a vertical probe 101b that is a vertical probe other than the vertical probe 101a.

[0032] 1, not only the vertical probe 101b but also a plurality of vertical probes 101 other than the vertical probe 101a are positioned around the vertical probe 101a. Therefore, the ultrasonic waves emitted from the vertical probe 101a and traveling diagonally downward are received by the plurality of vertical probes 101 including the vertical probe 101b.

[0033] The ultrasonic waves 112 shown in Fig. 5 are ultrasonic waves with the same emission angle as the ultrasonic waves 112 shown in Fig. 4. As shown in Fig. 5, when a thinning 201 occurs in the pipe 200, the ultrasonic waves 112 emitted from the vertical probe 101a and traveling diagonally downward are reflected by the inclined surface of the thinning 201 and propagate in the opposite direction to the vertical probe 101b. The amount of ultrasonic waves reflected by the inclined surface of the thinning increases as the depth of the thinning increases.

[0034] As a result, the amount of ultrasonic waves transmitted from the vertical probe 101a to the vertical probe 101b decreases as the depth of the thinning increases, resulting in a decrease in the intensity of the ultrasonic waveform transmitted by the vertical probe 101a and received by the vertical probe 101b.

[0035] Fig. 6A is a diagram showing an ultrasonic waveform 601 received when no thinning has occurred. Fig. 6B is a diagram showing an ultrasonic waveform 602 received when thinning has occurred. The horizontal axis in Fig. 6 represents time, and the vertical axis represents the amplitude of the ultrasonic waveform. The vertical axes in Fig. 6A and Fig. 6B are on the same scale.

[0036] When thinning occurs, the slope of the thinning blocks some of the ultrasonic waves, so the amplitude of the ultrasonic waveform 602 is smaller than the amplitude of the ultrasonic waveform 601. In this embodiment, the distribution of thinning is estimated by detecting the decrease in the amplitude of the ultrasonic waveform.

[0037] [Thinning inspection procedure] Next, a procedure for inspecting wall thickness reduction using the inspection device 1 according to this embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing an example of a wall-thickness reduction inspection procedure according to this embodiment.

[0038] The wall-thinning inspection is divided into a screening inspection and a detailed inspection. In the wall-thinning inspection, a screening inspection is first performed periodically using the inspection device 1 according to this embodiment. Then, if the evaluation value of the wall-thinning in the screening inspection exceeds a preset threshold, a detailed inspection is performed.

[0039] In the screening inspection, first, the inspection device 1 performs an initial state measurement process (S1). The initial state is a state in which no thinning occurs in the pipe 200. Examples of the initial state include when the pipe 200 is installed, when the pipe 200 is replaced with a new one, and the like.

[0040] In the initial state measurement process, the ultrasonic waveform recording unit 125 of the inspection device 1 records, for each combination of two vertical probes out of the multiple vertical probes 101, an ultrasonic waveform signal (hereinafter referred to as an "initial state ultrasonic waveform signal") obtained by receiving ultrasonic waves propagating between the two vertical probes 101. Then, the storage unit 126 stores the initial state ultrasonic waveform signal recorded by the ultrasonic waveform recording unit 125. The initial state ultrasonic waveform signal corresponds to the first received signal according to the present invention.

[0041] Next, the inspection device 1 performs a thinning distribution measurement process (S2). The thinning distribution measurement process is performed every time a predetermined period of time has elapsed. In the thinning distribution measurement process, the inspection device 1 two-dimensionally detects the area where thinning has occurred and calculates the depth of the thinning. The thinning distribution measurement process will be described later with reference to FIG. 8.

[0042] Next, the inspection device 1 predicts the depth of thinning at the time of the next measurement based on the measurement data up to the previous time and the current measurement data obtained in step S2 (S3).Then, the inspection device 1 determines whether the depth of thinning at the time of the next measurement predicted in step S3 (evaluation value of thinning) exceeds a predetermined threshold value (S4).

[0043] In step S4, when it is determined that the evaluation value of wall-thinning does not exceed the predetermined threshold (when S4 is judged as NO), the inspection device 1 performs the process of step S2 after a predetermined period has elapsed. On the other hand, in step S4, when it is determined that the evaluation value of wall-thinning exceeds the predetermined threshold (when S4 is judged as YES), the inspection device 1 determines that a detailed inspection is necessary.

[0044] If the inspection device 1 determines that a detailed inspection is necessary, the inspector performs a detailed inspection when or before the next thinning distribution measurement process to measure the depth of the thinning (remaining thickness) with high precision (S5). In the detailed measurement, the location and depth of the thinning are measured in detail using a conventional inspection device that measures thinning using ultrasonic waves emitted directly downward from a vertical probe.

[0045] Next, the inspection device 1 determines whether to perform repair or continuous monitoring based on the result of the detailed inspection in step S5 (S6).The inspection device then transmits the determination result to the company (plant operator) that manages the piping 200.

[0046] [Thinning distribution measurement processing] Next, the wall-thinning distribution measuring process performed in step S2 of the wall-thinning inspection procedure shown in FIG. 7 will be described with reference to FIG. FIG. 8 is a flowchart showing an example of a wall-thinning distribution measurement process.

[0047] First, the ultrasonic waveform recording unit 125 of the inspection device 1 records ultrasonic waveform signals (hereinafter referred to as "ultrasonic waveform signals during inspection") obtained by receiving ultrasonic waves propagating between the two vertical probes 101 for each combination of two vertical probes out of the multiple vertical probes 101 (S11). The ultrasonic waveform signals during inspection correspond to the second received signals of the present invention. The memory unit 126 stores the ultrasonic waveform signals during inspection recorded by the ultrasonic waveform recording unit 125. The memory unit 126 stores the ultrasonic waveform signals in the initial state described above.

[0048] Next, the calculation unit 127 calculates the attenuation rate η of the ultrasonic waveform signal during the inspection relative to the ultrasonic waveform signal in the initial state (S12). The attenuation rate η is calculated using the following formula (1).

[0049] [Number 1] TIFF2025128576000002.tif7153

[0050] In equation (1), P0 is the energy of the ultrasonic waveform signal in the initial state, and is calculated using equation (2) below. P1 is the energy of the ultrasonic waveform signal during inspection, and is calculated using equation (3) below.

[0051] [Number 2] TIFF2025128576000003.tif10153

[0052] [Number 3] TIFF2025128576000004.tif10153

[0053] In equation (2), u0 is the ultrasonic waveform signal in the initial state. In equation (3), u1 is the ultrasonic waveform signal during inspection. In equations (2) and (3), t1 is the maximum recording time of the ultrasonic waveform signal. However, the integration range need only be common to u0 and u1, and does not need to be limited to t1. In this way, by using equation (1), the attenuation rate η can be easily calculated. Note that there are other methods for expressing the degree of attenuation of waveform intensity than equation (1). Therefore, the attenuation rate according to the present invention is not limited to being calculated using equation (1).

[0054] Next, the calculation unit 127 maps the attenuation rate between the vertical probes 101 onto a plane coordinate system of the pipe 200 (S13). Fig. 9 is a diagram showing positions 801 of multiple vertical probes 101 arranged in a grid pattern on the pipe 200. As described above, the positions 801 of the multiple vertical probes 101 do not necessarily have to be set in a grid pattern, and may be arranged in a staggered pattern or any other regular pattern, or may be arranged randomly without regularity.

[0055] 9, the intervals between positions 801 along the axial direction of the pipe 200 are wider on the dorsal side (outer periphery side) of the pipe 200 and narrower on the ventral side (inner periphery side) of the pipe 200. To represent the positions 801 in a plane coordinate system, the pipe 200 is expanded in the axial and circumferential directions using the elbow angle 802 (γ), elbow curvature radius 803 (R), and pipe radius 804 (r) of the pipe 200.

[0056] Fig. 10 is a diagram showing the position 801 shown in Fig. 9 in a plane coordinate system 900. In Fig. 10, the position 901 corresponds to the position 801 shown in Fig. 9. In step S13, for example, the values ​​of the attenuation factor corresponding to the positions 901a and 901b are plotted on a line 902 connecting the positions 901a and 901b. In step S13, the calculation unit 127 plots the values ​​of the attenuation factor for all combinations of the positions 901 of the two vertical probes 101.

[0057] The number of plots can be set arbitrarily. For example, if the distance between position 901a and position 901b is 50 mm and plotting is performed every 0.1 mm, the number of plots will be 500. The greater the number of plots, the higher the resolution, and therefore the range of wall thinning can be estimated with high accuracy.

[0058] Fig. 11 is a diagram showing the state in which values ​​of the attenuation rate are plotted on the straight lines connecting the positions 901 of the two vertical probes 101 for all combinations of the positions 901 of the two vertical probes 101 shown in Fig. 10. No straight lines where the value of the attenuation rate is zero are drawn in Fig. 11. Fig. 11 shows straight lines where the value of the attenuation rate is greater than zero, i.e., straight lines 1002 that cross the wall-thinning range 1001.

[0059] At the point where the straight lines 1002 intersect, the values ​​of the attenuation rates of both lines are added together. The values ​​of the attenuation rates are added together using a well-known interpolation method such as linear interpolation. As shown in FIG. 11, the area where the straight lines 1002 overlap significantly can be estimated as the area of ​​thinning. This makes it possible to easily detect the area of ​​thinning that extends two-dimensionally across multiple vertical probes 101.

[0060] Next, the calculation unit 127 extracts a wall-thinning range by applying image filtering to the plane coordinate system 900 shown in Fig. 11 (S14 in Fig. 8). In step S14, the calculation unit 127 applies a two-dimensional low-pass filter to the plane coordinate system shown in Fig. 11 to extract a range where the sum of the attenuation rate values ​​is equal to or greater than a threshold.

[0061] Fig. 12 is a diagram showing a state in which a wall-thinning range is extracted by applying image filtering to the plane coordinate system shown in Fig. 11. The calculation unit 127 applies image filtering to the plane coordinate system to remove components (plots) equal to or less than a preset threshold. This makes it possible to remove unnecessary plots and highlight the wall-thinning range.

[0062] Point 1100 shown in FIG. 12 is the location where the sum of the attenuation rate values ​​is the largest. This point 1100 corresponds approximately to the point where the depth of the wall-thinning is deepest. Therefore, the portion where the depth of the wall-thinning is deepest can be easily detected. By the processing up to step S14, the calculation unit 127 estimates (detects) the range of the wall-thinning two-dimensionally and estimates (detects) the position where the wall-thinning is deepest.

[0063] Figure 13 is a diagram showing the state in which the extracted wall-thinning area shown in Figure 12 has been converted back into a three-dimensional coordinate system 1200. As shown in Figure 13, by displaying wall-thinning area 1201 in three-dimensional coordinate system 1200, the inspector can easily recognize where wall-thinning exists in pipe 200. Such a three-dimensional display allows the position and size of pipe 200 to be changed using an operating unit such as a computer mouse. As a result, the inspector can check wall-thinning area 1201 from any angle and at any size.

[0064] In recent years, attempts have been made to three-dimensionally predict the location of wall thinning using CFD (Computational Fluid Dynamics). The wall thinning range 1201 displayed three-dimensionally according to this embodiment can be easily compared with the analysis results using CFD. As a result, the three-dimensional display of the wall thinning range 1201 according to this embodiment can be used to verify the analysis results using CFD.

[0065] Next, the calculation unit 127 calculates the depth of the thinning based on the attenuation rate at the deepest position of the thinning (S15 in FIG. 8). This allows the calculation unit 127 to detect the depth of the deepest position of the thinning. After the process of step S15, the ultrasonic transmitting and receiving device 120 ends the thinning distribution measurement process.

[0066] The attenuation rate calculated in step S12 is affected by the shape of the thinned portion. Therefore, even if the depth of the deepest part is the same, the obtained attenuation rate is different. In this embodiment, this fact is utilized to conservatively calculate the thinned portion depth. That is, the thinned portion depth is set to a value with a margin so that it is not shallower than the actual thinned portion depth.

[0067] Fig. 14 is a diagram showing the propagation of ultrasonic waves emitted from the vertical probe 101a when an elliptical wall thinning 201 occurs in the pipe 200. As shown in Fig. 14, an elliptical wall thinning 201 occurs in the pipe 200. The deepest part 201a of the wall thinning 201 is the deepest part of the wall thinning 201.

[0068] The ultrasonic waves emitted from the vertical probe 101a include ultrasonic waves 113 and 114, which have different emission angles. The ultrasonic waves 113 pass through the wall-reduced portion 201 and are received by the vertical probe 101b. The ultrasonic waves 114 are reflected by the inclined surface of the wall-reduced portion 201 and propagate in the opposite direction to the vertical probe 101b. Therefore, the ultrasonic waves 114 are not received by the vertical probe 101b.

[0069] Like ultrasonic wave 114, ultrasonic waves reflected by the inclined surface of wall-reduced 201 are generated more frequently as the inclined surface area of ​​the wall-reduced is larger. On the other hand, even if the deepest part of the wall-reduced is at the same depth, the fewer inclined surfaces there are, the fewer ultrasonic waves that are reflected by the wall-reduced and change their propagation direction in the opposite direction. In other words, even if the deepest part of the wall-reduced is at the same depth, the attenuation rate is different.

[0070] Fig. 15 is a diagram showing the propagation of ultrasonic waves emitted from the vertical probe 101a when a slit-shaped wall thinning 202 occurs in the pipe 200. As shown in Fig. 15, an elliptical wall thinning 202 occurs in the pipe 200. The deepest part 202a of the wall thinning 202 is the deepest part of the wall thinning 202. The depth of the deepest part 202a is the same as the depth of the deepest part 201a in the wall thinning 201 shown in Fig. 14.

[0071] The ultrasonic waves radiated from the vertical probe 101a include ultrasonic waves 113 and 114 with different radiation angles. The ultrasonic waves 113 and 114 shown in FIG. 15 have the same radiation angles as the ultrasonic waves 113 and 114 shown in FIG. 14. As shown in FIG. 15, the slit-shaped thinning 202 has a smaller inclined surface area than the thinning 201. Therefore, the ultrasonic waves 113 and 114 cross over the thinning 202 and are received by the vertical probe 101b.

[0072] Thus, there are fewer ultrasonic waves whose propagation direction changes in the opposite direction by reflecting off the slit-shaped thinning 202 than those that reflect off the elliptical-shaped thinning 201 (see FIG. 14) and change the propagation direction in the opposite direction. Therefore, when the slit-shaped thinning 202 occurs, the attenuation rate of the ultrasonic wave waveform signal output from the vertical probe 101b is smaller than when the elliptical-shaped thinning 201 occurs. Put another way, even if the attenuation rates of the ultrasonic wave waveform signals are the same, the deepest depths vary depending on the shape of the thinning.

[0073] FIG. 16 is a graph showing the relationship between the attenuation rate and the depth of the thinning according to the shape of the thinning. In FIG. 16, the horizontal axis represents the depth of the deepest part of the thinning, and the vertical axis represents the attenuation rate. As shown in FIG. 16, as the depth of the deepest part of the thinning increases, the attenuation rate increases.

[0074] [[ID=I12]]For example, when the attenuation rate is A, the depth D1 of the deepest part in the elliptical-shaped thinning 201 is smaller than the depth D2 of the deepest part in the slit-shaped thinning 202 (D1 < D2). And when the values of the attenuation rates are the same, the depth of the deepest part in the elliptical-shaped thinning 201 is always smaller than the depth of the deepest part in the slit-shaped thinning 202.

[0075] Therefore, in this embodiment, the depth of the deepest part of the wall thinning is calculated from the attenuation rate of the ultrasonic waveform signal, assuming that the thinning is slit-shaped. In other words, the depth of the deepest part of the wall thinning is calculated assuming the deepest part of the wall thinning. This prevents the calculated depth of the deepest part of the wall thinning from being shallower than the actual depth of the deepest part of the wall thinning. As a result, repair or replacement work on the pipe can be performed before the thinning becomes deeper than the allowable range.

[0076] 2. Second embodiment The inspection device according to the second embodiment has the same configuration as the inspection device according to the first embodiment. The inspection device according to the second embodiment differs from the inspection device according to the first embodiment in that the measurement of the ultrasonic waveform signal is divided into multiple times. Therefore, here, the range in which the ultrasonic waveform signal is measured will be described, and descriptions that overlap with those of the first embodiment will be omitted.

[0077] Fig. 17 is a diagram showing the results of plotting attenuation factor values ​​on a line connecting the positions 901 of two probes for all combinations of the positions 901 of two probes within the measurement range according to the second embodiment. No lines with an attenuation factor value of zero are drawn in Fig. 17. Fig. 17 also shows a line with an attenuation factor value greater than zero, i.e., a line 1002 that crosses the wall-thinning range 1001.

[0078] 17, in the second embodiment, a measurement range 1301 is set, which is an area smaller than the area in which the multiple vertical probes 101 are arranged. The measurement range 1301 is large enough to include positions 901 (part of the multiple vertical probes 101) of the vertical probes 101 arranged in four rows and four columns. In the second embodiment, the number of ultrasonic waveform signals measured at one time is the number of combinations of the positions 901 of the multiple vertical probes 101 included in the measurement range 1301.

[0079] 18 is a diagram illustrating an example in which the measurement range 1301 according to the second embodiment is shifted to measure ultrasonic waveform signals at all positions of the plurality of vertical probes 101. As shown in Fig. 18, in the second embodiment, steps S11 to S15 shown in Fig. 8 are repeated while shifting the measurement range 1301. In this way, ultrasonic waveform signals are measured at all positions of the plurality of vertical probes 101 installed in the pipe 200, and the wall-thinning area 1001 is extracted.

[0080] For example, first, ultrasonic waveform signals of multiple vertical probes 101 within measurement range 1301A are measured to extract the thinning area. Next, ultrasonic waveform signals of multiple vertical probes 101 within measurement range 1301B are measured to extract the thinning area. Next, ultrasonic waveform signals of multiple vertical probes 101 within measurement range 1301C are measured to extract the thinning area. Then, after measuring the areas of all vertical probes 101, the thinning areas extracted in each measurement range are overlapped to finally extract the thinning area 1001.

[0081] The step to be repeated may be only step S11. In this case, the processing from step S12 onwards is performed after recording the ultrasonic waveform signals of all the vertical probes 101. The steps to be repeated may be set as appropriate, such as step S11 and step S12.

[0082] 17 and 18, the measurement range 1301 in the second embodiment is set to a size that includes the positions of 16 vertical probes 101 arranged in 4 rows and 4 columns. However, the size of the measurement range can be set appropriately depending on the dimensions of the pipe to be inspected and the measurement conditions, for example, to a range of 2 rows and 2 columns, 3 rows and 6 columns, or a range other than a rectangle. Furthermore, the size of the measurement range does not need to be constant, and the size of the first measurement range and the size of the second measurement range may be different.

[0083] The inspection device according to the second embodiment can also achieve the same effects as those of the first embodiment. That is, the inspection device according to the second embodiment can two-dimensionally detect the area where thinning has occurred and calculate the depth of the thinning. Furthermore, in the second embodiment, the number of ultrasonic waveform signals measured at one time can be reduced, thereby reducing the processing power of the ultrasonic waveform recording unit 125 and the calculation unit 127.

[0084] The inspection device and inspection method of the present invention have been described above, including their effects. However, the inspection device and inspection method of the present invention are not limited to the above-described embodiments, and various modifications are possible within the scope of the invention as defined in the claims.

[0085] In addition, in the present invention, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment.In addition, it is possible to add, delete, or replace part of the configuration of each embodiment with another configuration.

[0086] In this specification, the words "parallel" and "orthogonal" are used, but these do not mean only "parallel" and "orthogonal" in the strict sense, but also include "parallel" and "orthogonal" and may also mean a "substantially parallel" or "substantially orthogonal" state within a range in which the functions can be exerted. [Explanation of symbols]

[0087] 1...inspection device, 100...group of probes, 101, 101a, 101b...vertical probes, 111, 112, 113, 114...ultrasonic waves, 120...ultrasonic wave transmitting / receiving device, 121...changeover switch, 122...pulser receiver, 123...multiplexer, 124...amplifier, 125...ultrasonic wave recording unit, 126...storage unit, 127...calculation unit, 140...signal line, 200...piping, 201, 202...wall thinning, 201a, 202a...deepest part, 601, 602...ultrasonic wave, 900...plane coordinate system, 1001...wall thinning range, 1100...point, 1200...three-dimensional coordinate system, 1201...wall thinning range, 1301, 1301A, 1301B, 1301C...Measurement range

Claims

1. An inspection device for non-destructively inspecting an object to be inspected, a probe group having a plurality of probes attached perpendicularly to the surface of the inspection object and configured to transmit and receive ultrasonic waves; a recording unit that records a plurality of received signals obtained by receiving ultrasonic waves transmitted from a first probe included in the probe group by a plurality of probes other than the first probe; a calculation unit that calculates a plurality of attenuation indices representing the degree of attenuation of a plurality of second received signals received after a plurality of first received signals recorded before thinning occurs in the inspection object, among the plurality of received signals, and estimates the extent of thinning based on the plurality of attenuation indices. Inspection equipment.

2. The calculation unit calculates the attenuation index by dividing a difference between a first received signal and a second received signal corresponding to the first received signal by the second received signal. The inspection device according to claim 1 .

3. The calculation unit plots each attenuation index on a straight line connecting the first probe and a plurality of probes other than the first probe in a plane coordinate system, and detects a range of thinning based on a range where the straight lines overlap. The inspection device according to claim 1 or 2.

4. The calculation unit sums up the attenuation indices at the points where the straight lines intersect, and detects the point where the sum of the attenuation indices is the largest as the part where the wall thinning is deepest. The inspection device according to claim 3 .

5. The calculation unit calculates the depth of thinning based on the largest sum of the attenuation indexes. The inspection device according to claim 4.

6. The calculation unit calculates the depth of the thinning assuming a slit-shaped thinning. The inspection device according to claim 5 .

7. The calculation unit removes components whose attenuation index is equal to or less than a threshold. The inspection device according to claim 3 .

8. The calculation unit defines a measurement range having a size that includes a part of the group of probes, and performs measurements multiple times while shifting the measurement range, thereby causing the recording unit to record the multiple received signals. The inspection device according to claim 1 .

9. 1. An inspection method for non-destructively inspecting an object to be inspected by utilizing received signals acquired from a probe group having a plurality of probes that are attached perpendicularly to a surface of the object to be inspected and that transmit and receive ultrasonic waves, comprising: a recording unit that records a plurality of received signals obtained by receiving ultrasonic waves transmitted from a first probe included in the probe group by a plurality of probes other than the first probe; A calculation unit calculates a plurality of attenuation indices representing the degree of attenuation of a plurality of second received signals received after a plurality of first received signals recorded before the occurrence of wall thinning in the inspection object, among the plurality of received signals, and estimates the extent of wall thinning based on the plurality of attenuation indices. Testing method.

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