Inspecting method, inspecting device, and member repair method

Abstract

An inspecting method according to the present invention is an inspecting method for detecting a defective portion from a member being inspected, the method including: a first detection step for using an eddy current flaw detector to detect a first signal from an inspection region on the surface of the member being inspected; a second detection step for detecting a second signal from the inspection region using an ultrasonic plate thickness gauge; and a determination step for determining that there is a defective portion in the inspection region if at least one of the first signal and the second signal indicates an abnormal value.

Description

Inspection method, inspection device, and component repair method

[0001] The present invention relates to an inspection method and an inspection device for detecting defective parts such as corroded parts and cracks in an inspection target component, and a method for repairing the component.

[0002] When inspection target components, such as hollow components such as pipes and tanks, become corroded or damaged, problems such as leakage of contents can occur. For this reason, various inspection methods have been proposed for detecting defects such as corroded areas and cracks in inspection target components. For example, Patent Document 1 describes a method for detecting defects in pipes using an ultrasonic thickness gauge. Patent Document 2 describes a method for detecting cracks and corrosion-induced thinning in pipes using an eddy current flaw detector. Patent Document 3 describes a method for detecting defects such as thinning and cracks in inspection target components using an eddy current flaw detector.

[0003] Japanese Patent Application Laid-Open No. 62-124458 Japanese Patent Application Laid-Open No. 2008-32508 Japanese Patent No. 7205642

[0004] The method described in Patent Document 1 is a point measurement technique, and therefore cannot detect localized corrosion unless the entire surface of the inspected component is measured. Furthermore, ultrasonic thickness gauges typically detect multiple reflections of ultrasonic waves between two parallel surfaces, and calculate the thickness by multiplying the time interval between the reflections by the known speed of sound for each material of the inspected component, assuming that the time interval is the round-trip ultrasonic propagation time. Therefore, if the surface is uneven due to corrosion or the target surfaces are not parallel, the multiple reflections cannot be detected, and thickness measurement is not possible. As a result, the method described in Patent Document 1 may miss corroded areas. As a result, while thickness inspection requires measuring the thickness of the inspection area, even if the thickness of the healthy portion can be measured, it may not be possible to measure the thickness of the corroded thinning portion, potentially resulting in failure to detect the corroded thinning portion.

[0005] On the other hand, because an eddy current flaw detector is a device that detects changes in the thickness of a component being inspected, it is not possible to measure the absolute value of the thickness of the component being inspected using the methods described in Patent Documents 2 and 3. Furthermore, because the strength of the signal detected by an eddy current flaw detector depends on the amount of change in the thickness of the component being inspected, it is difficult for the methods described in Patent Documents 2 and 3 to detect corroded areas where the amount of change in thickness is small, such as areas where the material is uniformly thinned.

[0006] The present invention has been made to solve the above problems, and an object of the present invention is to provide an inspection method and an inspection device that can accurately detect defective parts in an inspected component. Another object of the present invention is to provide a component repair method that can prevent problems caused by defective parts in the component.

[0007] [1] The inspection method according to the present invention is an inspection method for detecting a defective part from a component to be inspected, and includes a first detection step of detecting a first signal from an inspection area on the surface of the component to be inspected using an eddy current flaw detector, a second detection step of detecting a second signal from the inspection area using an ultrasonic thickness gauge, and a determination step of determining that there is a defective part in the inspection area if at least one of the first signal and the second signal indicates an abnormal value.

[0008] [2] The inspection method according to the present invention is the inspection method according to [1] above, wherein the determination step includes the steps of determining that there is a crack in the inspection area when the first signal indicates an abnormal value and the second signal indicates a normal value, determining that there is pit-like thinning in the inspection area when both the first signal and the second signal indicate abnormal values, and determining that there is uniform thinning in the inspection area when the first signal indicates a normal value and the second signal indicates an abnormal value.

[0009] [3] A method for repairing a component according to the present invention includes a repair step of repairing or replacing a defective part of the component detected using the inspection method according to [1] or [2] above.

[0010] [4] The inspection device according to the present invention is an inspection device for detecting defective parts from an inspected component, and comprises an eddy current flaw detector that detects a first signal from an inspection area on the surface of the inspected component, an ultrasonic thickness gauge that detects a second signal from the inspection area, and an information processing device that determines that there is a defective part in the inspection area if at least one of the first signal and the second signal indicates an abnormal value.

[0011] [5] The inspection device according to the present invention is the inspection device according to [4] above, further comprising a moving unit that moves the eddy current flaw detector and the ultrasonic thickness gauge on the surface of the inspection target component.

[0012] According to the inspection method and inspection device of the present invention, it is possible to accurately detect defective parts in an inspection target component, and according to the member repair method of the present invention, it is possible to prevent the occurrence of problems caused by defective parts in a component.

[0013] Fig. 1 is a diagram showing the results of evaluating the relationship between the output signals of an eddy current flaw detector and an electromagnetic ultrasonic thickness gauge and the corroded areas and cracks. Fig. 2 is a schematic diagram showing the configuration of the self-propelled carriage shown in Fig. 1. Fig. 3 is a flowchart showing the flow of an inspection method according to one embodiment of the present invention. Fig. 4 is a diagram showing the inspection results of an example.

[0014] [Concept of the Present Invention] First, the concept of the inspection method and inspection device according to the present invention will be described.

[0015] Defective parts in hollow components such as pipes and tanks include corrosion and cracks, and corrosion can take the form of pit-like thinning or uniform thinning. Such defects need to be detected early because they can lead to problems such as leakage of contents. Therefore, the inventors of the present invention evaluated the relationship between the output signals of an eddy current flaw detector and an electromagnetic ultrasonic thickness gauge and the defects (particularly, corrosion and cracks) in order to detect corrosion and cracks. Specifically, a steel plate S with artificial flaws simulating corrosion and cracks, as shown in FIG. 1( b), was prepared. A self-propelled vehicle 1 equipped with an eddy current flaw detector and an electromagnetic ultrasonic thickness gauge was run over the steel plate S to evaluate the relationship between the output signals of the eddy current flaw detector and the electromagnetic ultrasonic thickness gauge and the corrosion and cracks.

[0016] Specifically, a mortar-shaped defect D1 (30φ, with a depth equivalent to 40% of the original thickness (12 mm) of the steel plate S) simulating a pit-like thinning and a V-groove D2 (5 mm deep, 100 mm wide) simulating a uniform thinning were formed in the steel plate S. The V-groove D2 was formed by reducing the thickness of the steel plate S by approximately 42% of its original thickness, which is generally a level that would be subject to detection. Furthermore, the end of the steel plate S with the mortar-shaped defect D1 formed was butted against the end of the steel plate S with the V-groove D2, simulating a crack at the seam of the steel plate S. The self-propelled carriage 1 was designed to be attracted and run by magnetic drive wheels 1a, and running instructions and flaw detection instructions were sent to the self-propelled carriage 1 via wireless communication from an external computer. An encoder was attached to one of the magnetic drive wheels 1a (see Figure 2), and the running distance of the self-propelled carriage 1 was measured and stored using the encoder.

[0017] An E-type coil was used as the eddy current flaw detector 2 (see Figure 2), and it was positioned so that the difference in detection signals could be obtained along the traveling direction of the self-propelled carriage 1. The E-type coil had a leg spacing of 20 mm, 200 turns, an excitation frequency of 10 kHz, and a lift-off of 3 mm. The E-type coil was arranged in three channels at a 30 mm pitch along the width direction of the self-propelled carriage 1, and measurements were taken by switching channels every 100 ms. The E-type coil was powered by a battery, which was a separate system from the self-propelled carriage 1 as a noise countermeasure. The detection signal was then AD converted within each E-type coil, and the detection signal was transmitted to an external computer via wireless communication every 100 ms and recorded.

[0018] The electromagnetic ultrasonic thickness gauge 3 (see Figure 2) was a shear wave generating type, and measurements were performed in the so-called echo-echo mode using a center frequency of 4 MHz. Furthermore, to detect the multiple-reflecting bottom echo, gates were set for the so-called B1 and B2 echoes, and the thickness of the steel plate S was calculated using the time difference between them. For the calculation, the shear wave sound velocity was set to 3,240 m / s. Synchronous addition was set to 8 times, and auto-gain was set to 100 dB. If the B1 and B2 echoes could not be detected in this auto-gain state, it was determined that the thickness was unmeasurable. The measurement results were transmitted to an external computer via wireless communication and recorded in synchronization with the measurement results of the eddy current flaw detector 2.

[0019] The evaluation results are shown in Figure 1(a). As shown in Figure 1(a), the output signal (eddy current flaw detection signal) of the eddy current flaw detector 2 shows changes at the cone-shaped defect D1 (pit-shaped thinning) and the seam (crack) of the steel sheet S, and the cone-shaped defect D1 and the seam were detected. In contrast, there was no significant change in the eddy current flaw detection signal at the V-groove D2 (uniform thinning), and the V-groove D2 could not be detected with a realistic S / N ratio. Specifically, the intensity of the eddy current flaw detection signal was smaller than that of the cone-shaped defect D1, which has approximately the same depth. This is thought to be because the width of the V-groove D2 is wider than the width of the eddy current flaw detector 2, and therefore the amount of change in sheet thickness detected is small.

[0020] In contrast, the output (thickness gauge reading) of the electromagnetic ultrasonic thickness gauge 3 always indicated the original thickness (12 mm) of the steel sheet S at the seam portion. Furthermore, at the mortar-shaped defect D1, an indication value indicating the thickness (remaining thickness) of the bottom portion was obtained only at the position corresponding to the bottom, and the reflected signal was weaker at the slope portion, so no indication value was obtained. Furthermore, at the V-groove D2, an indication value of a thickness (remaining thickness) thinner than the original thickness of the steel sheet S was obtained throughout the entire groove, confirming the presence of a thinned portion.

[0021] The above evaluation results can be summarized as shown in Table 1 below. That is, as shown in Table 1, in healthy sections, there is no reaction to the eddy current testing signal, and the thickness gauge reading indicates the original thickness of the steel plate S. In addition, in cracks, there is a reaction to the eddy current testing signal, and the thickness gauge reading indicates the original thickness of the steel plate S. In addition, in pit-shaped thinning, there is a reaction to the eddy current testing signal, and the thickness gauge reading indicates that measurement is not possible or the thickness reading indicates the remaining thickness of the steel plate S. In addition, in uniform thinning, there is no reaction to the eddy current testing signal, and the thickness gauge reading indicates the remaining thickness of the steel plate S.

[0022]

[0023] Therefore, as shown in Table 2 below, it has been newly discovered that by combining the output signal of the eddy current flaw detector and the output signal of the electromagnetic ultrasonic thickness gauge, it is possible to determine whether the inspection area is a sound area, has a crack, has pit-like thinning, or has uniform thinning. That is, as shown in Table 2, if there is no reaction to the eddy current flaw detector signal and the thickness gauge reading indicates the original thickness of the steel plate S, it can be determined that the inspection area is a sound area. Also, if there is a reaction to the eddy current flaw detector signal and the thickness gauge reading indicates the original thickness of the steel plate S, it can be determined that there is a crack in the inspection area. Also, if there is a reaction to the eddy current flaw detector signal and the thickness cannot be measured or the thickness reading indicates the residual pressure of the steel plate S, it can be determined that there is pit-like thinning in the inspection area. Also, if there is no reaction to the eddy current flaw detector signal and the thickness gauge reading indicates the original thickness of the steel plate S, it can be determined that there is uniform thinning in the inspection area.

[0024]

[0025] Therefore, the inspection method and inspection device of the present invention determine whether the inspection area is a healthy area or a defective area, and further whether the defective area is a crack, pit-like thinning, or uniform thinning, based on a combination of the output signal of the eddy current flaw detector and the output signal of the electromagnetic ultrasonic thickness gauge.

[0026] While uniform wall thinning refers to a smooth, uniformly corroded surface, continuous pitting due to drainage pools and other factors can occur. This condition is intermediate between the two, but the unevenness of the surface makes ultrasonic waves scattering, making measurement with an electromagnetic ultrasonic thickness gauge difficult. However, continuous pitting indicates frequent and continuous thickness changes. When inspecting such areas with an eddy current flaw detector, large-amplitude signals are detected continuously. Therefore, continuous pitting can be detected by combining an electromagnetic ultrasonic thickness gauge with an eddy current flaw detector. Thus, even when uniform wall thinning and sound sections are indistinguishable using an eddy current flaw detector alone, the presence or absence of wall thinning can be detected by the difference in the electromagnetic ultrasonic thickness gauge readings. Furthermore, single pitting and continuous pitting can be detected by the continuity of the eddy current flaw detector signal. In addition, since the ultrasonic thickness gauge may indicate the thickness of the original thick part surrounding the pit-like thinning, it is advisable to give priority to the eddy current testing signal when determining thinning.

[0027] FIG. 3 shows an example of the process flow for detecting defects in a component under inspection using Table 2. The judgment operation described below is performed by an information processing device, such as a computer, comparing the measured eddy current testing signal and thickness with the data shown in Table 2. More specifically, at least steps S2 to S4, S7, and S10, described below, are performed by the information processing device. As shown in FIG. 3, when detecting defects in a component under inspection using Table 2, first, an eddy current testing signal and thickness are measured in the inspection area of ​​the component under inspection using an eddy current flaw detector and an electromagnetic ultrasonic thickness gauge, and these measurement results are recorded in the information processing device (step S1). Note that the measurement position may be shifted depending on the placement of the eddy current flaw detector and the electromagnetic ultrasonic thickness gauge, so it is desirable to correct or modify it.

[0028] Next, it is determined whether the plate thickness in the inspection area can be measured (Step S2). If the plate thickness can be measured (Step S2: Yes), it is determined whether the measured plate thickness indicates the original thickness of the inspection target component (Step S3). If the measured plate thickness indicates the original thickness of the inspection target component (Step S3: Yes), it is determined whether there is a reaction to the eddy current inspection signal (Step S4). If there is a reaction to the eddy current inspection signal (Step S4: Yes), it is determined that there is a crack in the inspection area (Step S5). On the other hand, if there is no reaction to the eddy current inspection signal (Step S4: No), it is determined that the inspection area is sound (Step S6).

[0029] On the other hand, if it is determined in the processing of step S3 that the measured thickness is different from the original thickness of the inspected component (step S3: No), it is determined whether or not there is a reaction in the eddy current inspection signal (step S7). If there is a reaction in the eddy current inspection signal (step S7: Yes), it is determined that there is a single or continuous pit-like thinning in the inspection area (step S8). On the other hand, if there is no reaction in the eddy current inspection signal (step S7: No), it is determined that there is a uniform thinning in the inspection area (step S9). Furthermore, if the processing of step S2 fails to measure the thickness in the inspection area (step S2: No), it is determined whether or not there is a reaction in the eddy current inspection signal (step S10). If there is a reaction in the eddy current inspection signal (step S10: Yes), it is determined that there is a single or continuous pit-like thinning in the inspection area (step S11).

[0030] On the other hand, if there is no response to the eddy current testing signal (Step S10: No), it is determined that there may be a malfunction in the device, and the device is inspected (Step S12). For example, if the electromagnetic ultrasonic thickness gauge has no indication and no eddy current testing signal is detected, this indicates that the inner surface is so rough that the reflected signal of the electromagnetic ultrasonic signal does not return, but no eddy current testing signal is generated, and therefore a malfunction of the eddy current testing device is suspected. Alternatively, the lift-off of the eddy current testing device may be poor, resulting in the failure to detect eddy current testing signals or electromagnetic ultrasonic signals. Both of these are equipment malfunctions that require inspection and repair. Note that, while the determination is made based on the results of the thickness measurement in the example of Figure 3, it may also be made based on the results of the eddy current testing. Furthermore, the results of the thickness measurement and the results of the eddy current testing may be simultaneously compared to determine whether they correspond to any of the conditions in Table 2.

[0031] Thereafter, after recording the judgment result, the apparatus moves to the next inspection area and performs the same process to inspect the entire inspection area of ​​the inspection target component. The following describes in detail the configurations of the self-propelled carriage 1, eddy current flaw detector 2, and electromagnetic ultrasonic thickness gauge 3 used in the inspection method and inspection device according to the present invention.

[0032] [Self-propelled vehicle] The self-propelled vehicle 1 corresponds to the moving unit in the inspection device according to the present invention. The self-propelled vehicle 1 is a vehicle that adheres to the inspection target component and moves by itself. To perform flaw detection while moving over the inspection target component, the self-propelled vehicle 1 is equipped with an adhesion mechanism and a self-propelled mechanism. As an example, the self-propelled vehicle 1 is equipped with magnetic wheels so that it can adhere to the inspection target component while moving over it. In this case, the magnetic wheels may serve as both an adhesion mechanism and a traveling mechanism. As an example, a magnetic drive wheel is preferred as a traveling mechanism and adhesion mechanism. Another example is a permanent magnet endless track. A configuration may be adopted in which the self-propelled vehicle 1 has a magnetic adhesion mechanism and a driving device such as wheels or endless tracks for traveling. Furthermore, it is preferable that the self-propelled vehicle 1 is capable of climbing over and traveling over weld beads and the like. Furthermore, the position (travel distance, etc.) of the self-propelled vehicle 1 is measured using an encoder or the like and recorded as the inspection position. Any of the following may be used: attitude measurement using an inertial measurement unit (IMU), surveying / position measurement means such as a total station, or self-position detection using a GPS or the like. The flaw detection position of the self-propelled carriage 1 is recorded by some method. The self-propelled carriage 1 is preferably a device that operates wirelessly. If it is wireless, it is possible to inspect any range without being restricted by drive / signal transmission cables. Of course, the moving unit in the present invention is not limited to the above-mentioned self-propelled carriage 1. A normal carriage may be used instead of the self-propelled carriage 1 and moved manually. Furthermore, the self-propelled carriage 1 may be combined with an arm that can be operated by a drive unit and installed as part of a manufacturing facility.

[0033] [Eddy Current Flaw Detector] The eddy current flaw detector 2 is equipped with an excitation coil, a detection coil, and a signal processing unit including phase detection. Furthermore, when inspecting steel pipes, etc., the eddy current flaw detector 2 is equipped with an external magnetization exciter. The eddy current flaw detector 2 applies an excitation signal of any (appropriate) frequency to the excitation coil, generating eddy currents in the inspected material. The eddy currents generated near the surface of the inspected material are detected by the detection coil. If the inspected material has a flaw or its thickness changes, the distribution of the eddy currents changes, and the signal detected by the detection coil also changes. The detected signal is processed in the signal processing unit, including phase detection, to extract the detection voltage and phase information. When a differential detection coil is used, any thickness differences or flaws near the detection coil are output as a voltage signal. This makes it possible to detect thickness changes, cracks, flaws, etc. between the detection coils.

[0034] The size of the detector coil should be appropriately designed, taking into account the size of the defect to be detected and factors such as lift-off. When using a differential detector coil, the difference between the detector coil impedance and the change in the AC magnetic field near the detector coil is detected as a flaw detection signal. Therefore, if the size of the pit-like thinning to be detected is too large compared to the detector coil, there will be no difference between the two detector coils, and no detection signal will appear. Pit-like thinning is generally a cone-shaped thinning area approximately 10 to 30 mm in size, so it is preferable to use an eddy current detector with a size similar to this. When the test object is a ferromagnetic material, eddy currents are distributed only on the very surface. Therefore, to detect changes in the thickness of a ferromagnetic material, a magnetic field close to magnetic saturation is applied externally to reduce the magnetic permeability and distribute the eddy currents to the interior. For this reason, in this case, the eddy current detector 2 has a magnetizer for applying external magnetization. Considering that the magnetizer will be mounted on the self-propelled vehicle 1, a permanent magnet is preferable, and rare-earth magnets such as neodymium magnets are preferable from the standpoints of cost and magnetic field strength. A strong magnet contributes to miniaturization and weight reduction.

[0035] The eddy current flaw detector 2 detects changes in eddy currents between differential detection coils, and therefore generates an output if there is a difference in thickness at each position of the differential coil. In defective areas, the thickness of the metal part decreases due to loss of material or oxidation, etc. This causes a change in the eddy current distribution, allowing thinning to be detected by eddy current flaw detection. There is a correlation between the amplitude of the eddy current flaw detection signal and the rate of thinning, which can be quantified in advance using test pieces, etc. By creating an artificial defect of the detection target (depth / thickness), the corrosion depth can be quantified from the detected amplitude.

[0036] In this embodiment, three eddy current flaw detectors are arranged in the width direction of the moving part (self-propelled carriage 1). The width direction of the moving part is on the same plane as, and perpendicular to, the traveling direction of the self-propelled carriage 1. Arranging multiple eddy current flaw detectors in the width direction in this manner is preferable because it allows for a wider measurement range than a single detector. The dimensions of each eddy current flaw detector can be determined as appropriate. However, sensitivity tends to decrease when the eddy current flaw detector is larger compared to the pit-like thinning. Therefore, using multiple eddy current flaw detectors rather than a single one is preferable because it maintains sensitivity, expands the measurement range, and shortens the measurement time. However, care should be taken when increasing the number of eddy current flaw detectors too much, as this can result in problems such as the moving part becoming larger, making it difficult to handle the entire inspection device, including the moving part, and complicating the tracking structure between the inspection object and the eddy current flaw detector.

[0037] [Electromagnetic ultrasonic thickness gauge] The electromagnetic ultrasonic thickness gauge 3 comprises a coil and a magnet, and induces ultrasonic waves in the test object, which is a conductive material, by Lorentz force or magnetostriction force, which is generated by the interaction between a magnetic field applied by the magnet placed close to the test object and eddy currents generated in the test object when a current pulse is applied to a coil placed close to the test object. A permanent magnet or an electromagnet can be used to apply the magnetic field to the test object. When the gauge is loaded onto the self-propelled carriage 1, it is preferable to use a rare earth magnet (permanent magnet) such as a neodymium magnet from the viewpoint of weight.

[0038] When using a permanent magnet, the permanent magnet is brought within a few millimeters (approximately 1 to 5 mm) of the test object and a magnetic field is applied. Next, a coil is placed within the area where the magnetic field is applied, and a single or multiple burst current of approximately several hundred kHz to 5 MHz is applied. This induces eddy currents on the surface of the test object facing the coil, causing an interaction between the eddy current and the static magnetic field applied by the magnet, resulting in a Lorentz force on the test object. As a result, ultrasonic waves of the same frequency as the applied current are generated and propagate within the test object. The ultrasonic vibrations generated on the surface propagate within the test object, return to the surface, and vibrate it.

[0039] Since the signal can be detected by a coil, which is the reverse process of generation, the transmitting probe and receiving probe can be the same. The detected signal is amplified by an appropriate preamplifier, then input to a computer or microcomputer via AD conversion. It is then averaged (noise removed) by appropriate synchronous addition to calculate the ultrasonic propagation time. When used as a plate thickness gauge, the plate thickness can be determined by calculating the time difference between the reflection times when multiple reflections occur on the surface and bottom of the object, and multiplying this by the known speed of sound. For example, the speed of sound in steel can be calculated using the known speed of sound, approximately 3,240 m / s (for shear waves). The speed of sound is calibrated appropriately based on the type of steel and alloy composition.

[0040] Because electromagnetic ultrasonic waves are generated by eddy currents induced by a coil and a static magnetic field applied by a magnet or the like, they can be used without being placed in close contact with the object to be measured. Furthermore, thickness gauges using electromagnetic ultrasonic waves are stable against changes in the probe angle and other disturbances. These advantages make the use of electromagnetic ultrasonic thickness gauges highly suitable when automating the inspection method and / or inspection device according to the present invention.

[0041] The captured ultrasonic waveform and plate thickness calculation results are preferably transmitted wirelessly to an external computer, etc. Alternatively, they are transmitted to the control unit of the self-propelled carriage 1 or the eddy current flaw detector 2, and are recorded and saved together. These are used as plate thickness measurement results together with the eddy current flaw detection results and the carriage travel results (position, posture, etc.).

[0042] In explaining the present invention, an electromagnetic ultrasonic thickness gauge has been used as an example of an ultrasonic thickness gauge. As described above, this is because electromagnetic ultrasonic thickness gauges are relatively easy to use. However, the effects of the present invention can be similarly achieved with ultrasonic thickness gauges other than electromagnetic ultrasonic thickness gauges. In this case, a suitable medium is simply passed between the test object and the ultrasonic thickness gauge. For example, water, ultrasonic gel, or the like is applied to or interposed between the test object and the ultrasonic thickness gauge, and the thickness of the test object is measured using the ultrasonic thickness gauge.

[0043] In this example, a pipe with actual corrosion thinning was inspected using the present invention. As shown in Figure 4(a), a quarter of the circumference of the pipe P was inspected from the bottom to the side using a self-propelled vehicle. The original wall thickness of the pipe was 10 mm, and aluminum tape (conductive tape) was applied to two locations on the intact section to simulate cracks. It was previously known that the lower part of the pipe had adjacent pit-like thinning areas due to corrosion and uniform thinning areas. An E-type coil was used as the eddy current flaw detector 2, and it was positioned so that the difference in detection signals could be obtained in the direction of travel of the self-propelled vehicle 1. The E-type coil had a leg spacing of 20 mm, 200 turns, an excitation frequency of 10 kHz, and a lift-off of 3 mm. Three E-type coil channels were arranged at a 30 mm pitch along the width direction of the self-propelled vehicle 1, and measurements were performed by switching channels every 100 ms. The E-type coils were powered by batteries, and the detection signals were converted into digital data within each E-type coil. The detection signals were then transmitted every 100 ms via wireless communication to an external computer (information processing device), where they were recorded and evaluated. Meanwhile, the measurements from the electromagnetic ultrasonic thickness gauge were collected at 100 mm intervals, and a variation of ±50 mm (±1σ) was used as the error bar to calculate the results.

[0044] The measurement results are shown in Figure 4(b). As shown in Figure 4(b), the amplitude of the eddy current testing signal is small in the healthy section. In contrast, the amplitude of the eddy current testing signal is large in the simulated flaw area and near the bottom of the pipe, clearly indicating a change in the pipe's wall thickness. Meanwhile, the electromagnetic ultrasonic thickness gauge measurement values ​​indicate the original wall thickness of approximately 10 mm in the healthy section, with little variation. In contrast, near the bottom of the pipe, the electromagnetic ultrasonic thickness gauge measurement values ​​indicate a wall thickness thinner than the original thickness, with greater variation. From these results, it was determined that the pipe had a simulated crack flaw on the side, a pit-like thinning area near the bottom of the pipe, and a uniform thinning area next to it, and that the pipe was healthy except for these two areas. This confirms that the present invention can accurately detect defective parts of a pipe.

[0045] Although the present invention has been described above as an embodiment, the present invention is not limited to the descriptions and drawings that form part of the disclosure of the present invention. In other words, other embodiments, examples, and operational techniques that can be made by those skilled in the art based on the present invention are all included in the scope of the present invention.

[0046] According to the present invention, it is possible to provide an inspection method and an inspection device capable of accurately detecting defective parts in an inspected component, and also to provide a component repair method capable of suppressing the occurrence of problems caused by defective parts in the component.

[0047] 1 Self-propelled cart 1a Drive wheel 2 Eddy current flaw detector 3 Electromagnetic ultrasonic thickness gauge D1 Mortar-shaped defect D2 V-groove P Pipe S Steel plate

Claims

1. An inspection method for detecting a defective part from an inspected component, comprising: a first detection step of detecting a first signal from an inspection area on the surface of the inspected component using an eddy current flaw detector; a second detection step of detecting a second signal from the inspection area using an ultrasonic thickness gauge; and a determination step of determining that a defective part is present in the inspection area if at least one of the first signal and the second signal exhibits an abnormal value.

2. The inspection method according to claim 1, wherein the determining step includes the steps of determining that there is a crack in the inspection area when the first signal indicates an abnormal value and the second signal indicates a normal value, determining that there is pit-like thinning in the inspection area when both the first signal and the second signal indicate abnormal values, and determining that there is uniform thinning in the inspection area when the first signal indicates a normal value and the second signal indicates an abnormal value.

3. A method for repairing a component, comprising a repair step of repairing or replacing a defective part of the component detected using the inspection method according to claim 1 or 2.

4. An inspection device for detecting defects in a component to be inspected, comprising: an eddy current flaw detector that detects a first signal from an inspection area on the surface of the component to be inspected; an ultrasonic thickness gauge that detects a second signal from the inspection area; and an information processing device that determines that a defect exists in the inspection area when at least one of the first signal and the second signal indicates an abnormal value.

5. An inspection device according to claim 4, further comprising a moving unit for moving the eddy current flaw detector and the ultrasonic thickness gauge on the surface of the inspected component.

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