Inspection method, inspection device, and member repair method

Abstract

The present application relates to an inspection method for detecting a defect site from an inspected member, comprising: a first detection step of detecting a first signal from an inspection region on a surface of the inspected member using an eddy current flaw detector; a second detection step of detecting a second signal from the inspection region using an ultrasonic thickness gauge; and a determination step of determining that the inspection region has the defect site when at least one of the first signal and the second signal indicates an abnormal value.

Description

Technical Field

[0001] This invention relates to an inspection method, an inspection device, and a repair method for detecting defects such as corrosion and cracks in inspected components. Background Technology

[0002] If inspected components, such as hollow structures like piping and storage tanks, become corroded or damaged, problems such as leakage of contents can occur. Therefore, various inspection methods have been proposed to detect corrosion, cracks, and other defects in the inspected components. For example, Patent Document 1 describes a method for detecting piping defects using an ultrasonic thickness gauge. Patent Document 2 describes a method for detecting cracks and corrosion thinning in piping using an eddy current flaw detector. Furthermore, Patent Document 3 describes a method for detecting thinning and cracks in inspected components using an eddy current flaw detector.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 62-124458

[0006] Patent Document 2: Japanese Patent Application Publication No. 2008-32508

[0007] Patent Document 3: Japanese Patent No. 7205642 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The method described in Patent Document 1 is a point measurement technique. Therefore, if the entire surface of the inspected component is not measured, localized corrosion sites cannot be detected. Furthermore, ultrasonic thickness gauges typically detect multiple reflections of ultrasonic waves generated between two parallel surfaces. The time interval between these reflections is assumed to be the round-trip time of the ultrasonic wave. The thickness is calculated by multiplying the ultrasonic wave propagation time by the known speed of sound for each material of the inspected component. Therefore, when corrosion creates unevenness on the surface, or when the measured surfaces are not parallel, multiple reflections cannot be detected, making thickness measurement impossible. Consequently, according to the method described in Patent Document 1, there is a possibility of missing corrosion sites. As a result, while it is necessary to measure the thickness of the inspection area during thickness inspection, even if the thickness of intact areas can be measured, the thickness of corroded or thinned areas may sometimes be unmeasurable, leading to the possibility of failing to detect corroded or thinned areas.

[0010] On the other hand, since eddy current flaw detectors are devices that detect changes in the thickness of the inspected component, the methods described in Patent Documents 2 and 3 cannot measure the absolute value of the thickness of the inspected component. Furthermore, the signal intensity detected by the eddy current flaw detector depends on the amount of change in the thickness of the inspected component; therefore, the methods described in Patent Documents 2 and 3 are difficult to detect corrosion areas with small changes in thickness, such as uniformly thinned areas.

[0011] This invention was made to solve the aforementioned problems, and its object is to provide an inspection method and apparatus capable of detecting defects in inspected components with high precision. Furthermore, another object of this invention is to provide a method for repairing components that can suppress the occurrence of malfunctions caused by defects in the components.

[0012] Methods for solving problems

[0013] [1] The inspection method of the present invention is an inspection method for detecting defective parts from an inspected component, comprising: a first detection step, using an eddy current flaw detector to detect a first signal from an inspection area on the surface of the inspected component; a second detection step, using an ultrasonic thickness gauge to detect a second signal from the inspection area; and a determination step, determining that a defective part exists in the inspection area if at least one of the first signal and the second signal indicates an abnormal value.

[0014] [2] The inspection method of the present invention, according to the inspection method of [1] above, the determination step includes the following steps: when the first signal represents an abnormal value and the second signal represents a normal value, it is determined that there is a crack in the inspection area; when both the first signal and the second signal represent abnormal values, it is determined that there is pitting thinning (pitting thinning) in the inspection area; when the first signal represents a normal value and the second signal represents an abnormal value, it is determined that there is uniform thinning in the inspection area.

[0015] [3] The repair method of the component of the present invention includes a repair step, which repairs or replaces the defective parts of the component detected by the inspection method described in [1] or [2] above.

[0016] [4] The inspection device of the present invention is an inspection device for detecting defective parts from an inspected component, comprising: an eddy current flaw detector for detecting a first signal from an inspection area on the surface of the inspected component; an ultrasonic thickness gauge for detecting a second signal from the inspection area; and an information processing device for determining that a defective part exists in the inspection area when at least one of the first signal and the second signal indicates an abnormal value.

[0017] [5] The inspection device of the present invention, in the inspection device of [4] above, includes a moving part, which is used to move the eddy current flaw detector and the ultrasonic thickness gauge on the surface of the component to be inspected.

[0018] Invention Effects

[0019] According to the inspection method and apparatus of the present invention, defects can be detected from the inspected component with high precision. The component repair method according to the present invention can suppress the occurrence of faults caused by defects in the component. Attached Figure Description

[0020] Figure 1 This is a graph showing the evaluation results obtained by comparing the output signals of the eddy current flaw detector and the electromagnetic ultrasonic thickness gauge with the corrosion sites and cracks.

[0021] Figure 2 It means Figure 1 The diagram shows the structure of the self-propelled trolley.

[0022] Figure 3 This is a flowchart illustrating an inspection method according to one embodiment of the present invention.

[0023] Figure 4 This is a graph showing the inspection results of the embodiment. Detailed Implementation

[0024] [Concept of this invention]

[0025] First, the concepts of the inspection method and inspection device involved in this invention will be explained.

[0026] Defects in hollow components such as piping and storage tanks include corrosion and cracks. Corrosion can manifest as point-like thinning or uniform thinning. These defects can lead to leaks and other malfunctions, thus requiring early detection. Therefore, the inventors of this application, aiming to detect corrosion and cracks, evaluated the relationship between the output signals of an eddy current flaw detector and an electromagnetic ultrasonic thickness gauge and the defects (especially corrosion and cracks). Specifically, they prepared to develop a simulation... Figure 1 (b) shows the steel plate S with artificially created corrosion sites and cracks. A self-propelled trolley 1 equipped with an eddy current flaw detector and an electromagnetic ultrasonic thickness gauge is made to travel on the steel plate S, thereby evaluating the relationship between the output signals of the eddy current flaw detector and the electromagnetic ultrasonic thickness gauge and the corrosion sites and cracks.

[0027] Specifically, on the steel plate S, a pit-like defect D1 (30) simulating point-like thinning is formed. The depth is equivalent to 40% of the original thickness (12mm) of the steel plate S, and a V-groove D2 (5mm deep, 100mm wide) simulating uniform thinning is also present. The V-groove D2 reduces the thickness of the steel plate S by approximately 42% compared to its original thickness, which is generally considered a detection target. Furthermore, by butt-joining the end of the steel plate S with the pitted defect D1 to the end of the steel plate S with the V-groove D2, the joint of the steel plate S is simulated as a crack. The self-propelled trolley 1 is configured to achieve adsorption and movement by means of magnetic drive wheels 1a, and the external computer provides movement and flaw detection instructions to the self-propelled trolley 1 via wireless communication. Furthermore, in one of the magnetic drive wheels 1a (refer to...), Figure 2 An encoder is installed on the self-propelled trolley 1 to measure and save the travel distance of the trolley 1.

[0028] As an eddy current flaw detector 2 (refer to) Figure 2 The system employs E-type coils configured to acquire differential detection signals along the travel direction of the self-propelled trolley 1. The E-type coils have a pole spacing of 20mm, 200 turns, an excitation frequency of 10kHz, and a lift-off distance of 3mm. Furthermore, three channels of the E-type coils are arranged at 30mm intervals along the width of the self-propelled trolley 1, with channel switching for measurement every 100ms. The E-type coils are powered by batteries and, as a noise countermeasure, are designed as an independent system from the self-propelled trolley 1. The detection signals are converted from analog to digital (AD) signals within each E-type coil, and the detection signals are transmitted wirelessly to an external computer and recorded every 100ms.

[0029] As an electromagnetic ultrasonic thickness gauge 3 (reference) Figure 2 A transverse wave electromagnetic ultrasonic thickness gauge with a center frequency of 4MHz was used for measurement via an echo-echo mode. To detect the bottom echo with multiple reflections, thresholds 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. The transverse wave velocity was set to 3240 m / s. The synchronous accumulation was set to 8 times, and the automatic gain was set to a maximum of 100 dB. If the B1 and B2 echoes could not be detected under this automatic gain setting, the plate thickness was determined to be unmeasurable. The measurement results were transmitted wirelessly to an external computer and recorded synchronously with the measurement results of the eddy current flaw detector 2.

[0030] exist Figure 1 (a) represents the evaluation result. For example... Figure 1As shown in (a), changes were observed in the output signal (eddy current testing signal) of the eddy current flaw detector 2 at the pit-like defect D1 (point thinning) and the steel plate S-joint (crack), and the pit-like defect D1 and the joint could be detected. In contrast, at the V-groove D2 (uniform thinning), the eddy current testing signal did not change significantly, and the V-groove D2 could not be detected under the actual signal-to-noise ratio (S / N ratio). Specifically, the intensity of the eddy current testing signal was lower than that of the pit-like defect D1, which had a similar depth. This is believed to be because the width of the V-groove D2 is wider than the width of the eddy current flaw detector 2, so the detected change in plate thickness is smaller.

[0031] In contrast, regarding the output (thickness gauge indication value) of the electromagnetic ultrasonic thickness gauge 3, at the splice seam, the indication value consistently indicates the original thickness (12mm) of the steel plate S. Furthermore, at the pit-like defect D1, an indication value representing the bottom thickness (remaining thickness) is only obtained at the position corresponding to its bottom; the reflected signal weakens at the beveled surface, making it impossible to obtain an indication value. Additionally, in the V-groove D2, an indication value for the thickness (remaining thickness) less than the original thickness of the steel plate S is obtained throughout the entire range, confirming the existence of a thinned area.

[0032] The evaluation results summarized above are as shown in Table 1 below. That is, as shown in Table 1, in intact areas, there is no response in the eddy current testing signal, and the thickness gauge reading indicates the original thickness of steel plate S. Conversely, at crack locations, the eddy current testing signal is present, and the thickness gauge reading indicates the original thickness of steel plate S. Furthermore, at points of thinning, the eddy current testing signal is present, but the thickness gauge reading either cannot be measured or indicates the remaining thickness of steel plate S. Additionally, at areas of uniform thinning, the eddy current testing signal is absent, and the thickness gauge reading indicates the remaining thickness of steel plate S.

[0033] Table 1

[0034] (Table 1)

[0035] Therefore, the following new information is obtained: As shown in Table 2 below, by combining the output signal of the eddy current flaw detector with the output signal of the electromagnetic ultrasonic thickness gauge, it is possible to determine whether the inspected area is an intact part, a crack, point-like thinning, or uniform thinning. That is, as shown in Table 2, if the eddy current flaw detector signal is unresponsive and the thickness gauge reading indicates the original thickness of the steel plate S, the inspected area can be determined to be an intact part. Furthermore, if the eddy current flaw detector signal is responsive and the thickness gauge reading indicates the original thickness of the steel plate S, it can be determined that the inspected area has a crack. Furthermore, if the eddy current flaw detector signal is responsive but the plate thickness cannot be measured, or the plate thickness reading indicates the remaining pressure of the steel plate S, it can be determined that the inspected area has point-like thinning. Furthermore, if the eddy current flaw detector signal is unresponsive and the thickness gauge reading indicates the original thickness of the steel plate S, it can be determined that the inspected area has uniform thinning.

[0036] Table 2

[0037] (Table 2)

[0038] Therefore, in the inspection method and inspection device involved in this invention, based on the combination of the output signal of the eddy current flaw detector and the output signal of the electromagnetic ultrasonic thickness gauge, it is determined whether the inspection area is an intact part or a defective part, and further determined whether the defective part is a crack, point thinning, or uniform thinning.

[0039] Furthermore, uniform thinning refers to a smooth and uniform corrosion on the surface of the inspected component, but it can also exist in a state of continuous point-like thinning due to fluid accumulation. This state is an intermediate state between the two, but because the measured surface becomes uneven, ultrasonic waves are scattered, making it difficult to measure with an electromagnetic ultrasonic thickness gauge. However, continuous point-like thinning indicates frequent and continuous changes in plate thickness. If an eddy current flaw detector is used to inspect such areas, a continuous large-amplitude signal will be detected. Therefore, by combining an electromagnetic ultrasonic thickness gauge with an eddy current flaw detector, continuous point-like thinning can also be detected. In this way, even if uniform thinning and intact areas cannot be distinguished by an eddy current flaw detector alone, the difference in the readings of the electromagnetic ultrasonic thickness gauge can be used to determine whether thinning has occurred. In addition, single-point point-like thinning and continuous point-like thinning can be detected based on whether the eddy current flaw detector signal is continuous. Furthermore, since the ultrasonic thickness gauge may indicate the plate thickness of the original thickness area around the point-like thinning, the eddy current flaw detector signal can be used as a primary reference for thinning determination.

[0040] exist Figure 3This illustrates an example of a process flow for detecting defects in an inspected component using Table 2. Furthermore, the judgment actions described below are performed by comparing the measured eddy current testing signal and plate thickness with the data shown in Table 2 using an information processing device such as a computer. More specifically, at least steps S2-S4, S7, and S10, described later, are performed by the information processing device. Figure 3 As shown, when using Table 2 to inspect the defective parts of the inspected component, firstly, an eddy current flaw detector and an electromagnetic ultrasonic thickness gauge are used to measure the eddy current flaw detection signal and plate thickness in the inspection area of ​​the inspected component, and these measurement results are recorded in the information processing device (step S1). In addition, the measurement position may be offset due to the configuration position of the eddy current flaw detector and the electromagnetic ultrasonic thickness gauge, so it is desirable to compensate and correct for this.

[0041] Next, it is determined whether the plate thickness has been successfully measured in the inspection area (step S2). If the plate thickness has been successfully measured (step S2: yes), it is determined whether the measured plate thickness represents the original thickness of the inspected component (step S3). Then, if the measured plate thickness represents the original thickness of the inspected component (step S3: yes), it is determined whether there is a reaction in the eddy current testing signal (step S4). If there is a reaction in the eddy current testing signal (step S4: yes), it is determined that a crack exists in the inspection area (step S5). On the other hand, if there is no reaction in the eddy current testing signal (step S4: no), it is determined that the inspection area is an intact part (step S6).

[0042] On the other hand, in step S3, if it is determined that the measured plate thickness is different from the original thickness of the inspected component (step S3: No), it is determined whether there is a reaction in the eddy current testing signal (step S7). If there is a reaction in the eddy current testing signal (step S7: Yes), it is determined that there is single-point or continuous point-like thinning in the inspection area (step S8). On the other hand, if there is no reaction in the eddy current testing signal (step S7: No), it is determined that there is uniform thinning in the inspection area (step S9). Furthermore, in step S2, if the plate thickness cannot be measured in the inspection area (step S2: No), it is determined whether there is a reaction in the eddy current testing signal (step S10). If there is a reaction in the eddy current testing signal (step S10: Yes), it is determined that there is single-point or continuous point-like thinning in the inspection area (step S11).

[0043] On the other hand, if there is no response in the eddy current testing signal (step S10: No), it is determined that the device may be malfunctioning, and a device inspection is performed (step S12). For example, if the electromagnetic ultrasonic thickness gauge has no indication value and no eddy current testing signal is detected, it indicates that although the inner wall is rough enough that the reflected signal of the electromagnetic ultrasonic signal cannot return, no eddy current testing signal is still output, so the eddy current testing instrument is suspected of being malfunctioning. Or it may be suspected that the lifting state of the eddy current testing instrument has become abnormal, resulting in the inability to detect the eddy current testing signal or the electromagnetic ultrasonic signal. All of the above situations are considered device malfunctions and require inspection and maintenance. In addition, in Figure 3 In this example, the judgment is made starting from the results of plate thickness measurement, but it can also start from the results of eddy current testing. Alternatively, the results of plate thickness measurement and eddy current testing can be compared simultaneously to determine which scenario in Table 2 corresponds to.

[0044] After recording the judgment result, the device moves to the next inspection area and performs the same process, thereby inspecting all inspection areas of the component being inspected. The structure of the self-propelled trolley 1, the eddy current flaw detector 2, and the electromagnetic ultrasonic thickness gauge 3 used in the inspection method and apparatus of this invention will be described in detail below.

[0045] [Self-propelled trolley]

[0046] In the inspection apparatus of the present invention, the self-propelled trolley 1 functions as a moving part. The self-propelled trolley 1 is a trolley that moves autonomously by adhering to the component being inspected. Because it performs flaw detection while moving on the component being inspected, the self-propelled trolley 1 has both an adsorption mechanism and a travel mechanism. For example, the self-propelled trolley 1 is equipped with magnetic wheels to allow it to move and adhere to the component being inspected. In this case, the magnetic wheels can also serve as both the adsorption mechanism and the travel mechanism. For example, it is preferable that the travel mechanism, which consists of magnetically driven wheels, also functions as the adsorption mechanism. Alternatively, it can have tracks with permanent magnets. It can be configured to have both a magnet-based adsorption mechanism and a drive mechanism such as wheels or tracks for movement. Furthermore, it is preferable to have a specification that allows it to cross and move even where welds or the like are present. Additionally, the position (travel distance, etc.) of the self-propelled trolley 1 can be measured using an encoder or similar means and recorded as the flaw detection position. It can also utilize any of the following methods: attitude measurement based on an inertial measurement unit (IMU), surveying / position measurement means such as a total station, or self-position detection based on GPS. The flaw detection position of the self-propelled trolley 1 can be recorded using any of these methods. Preferably, the self-propelled trolley 1 is a device that operates wirelessly. If it is wireless, it is not limited by drive or signal transmission cables, and can perform inspections within any range. Of course, the moving part of the present invention is not limited to the self-propelled trolley 1 described above. A regular trolley can be used instead of the self-propelled trolley 1, driven manually. Alternatively, it can be combined with a robotic arm that can be moved by a drive device, and installed as part of a manufacturing equipment, instead of the self-propelled trolley 1.

[0047] Eddy current flaw detector

[0048] The eddy current flaw detector 2 includes an excitation coil, a detection coil, and a signal processing unit that includes phase detection. Furthermore, when inspecting steel pipes, the eddy current flaw detector 2 also includes an externally magnetized exciter. The eddy current flaw detector 2 applies an excitation signal of any (suitable) frequency to the excitation coil, generating eddy currents in the inspected component. The eddy currents generated on the surface of the inspected component are detected by the detection coil. If damage or a change in thickness exists in the inspected component, the distribution of the eddy currents changes, and the signal detected by the detection coil changes. The signal processing unit performs processing including phase detection on the detected signal, extracting the detection voltage and phase information. When using a differential detection coil, if a thickness difference or damage occurs near the detection coil, it is output as a voltage signal. This allows for the detection of thickness variations, cracks, defects, etc., between the detection coils.

[0049] The size of the detection coil is rationally designed considering the size and lifting characteristics of the defects to be detected. When using a differential detection coil, the difference in impedance of the detection coil and the change in the AC magnetic field near the detection coil are detected as flaw detection signals. Therefore, if the size of the point-like thinning of the target object is too large relative to the detection coil, the difference between the two detection coils disappears and is not reflected as a detection signal. Generally, point-like thinning is a bowl-shaped thinning portion of about 10-30 mm; therefore, the size of the eddy current flaw detector is preferably set to be the same as its size. When the component being inspected is a strongly magnetic material, eddy currents are only distributed on the surface layer. Therefore, in order to detect changes in the wall thickness of a strongly magnetic material, a magnetic field close to the magnetic saturation level needs to be applied externally to reduce the permeability and distribute the eddy currents to the interior. Therefore, in this case, the eddy current flaw detector 2 has a magnetizer for applying external magnetization. Considering the case of mounting on a self-propelled trolley 1, the magnetizer is preferably a permanent magnet; furthermore, from the viewpoint of cost and magnetic field strength, rare-earth magnets such as neodymium magnets are preferred. The stronger the magnetic force of a magnet, the more conducive it is to miniaturization and weight reduction.

[0050] Eddy current flaw detector 2 detects changes in eddy currents between differential coils. Therefore, as long as there is a difference in thickness at the respective locations of the two differential coils, an output will be generated. At the defect location, due to material loss or oxide formation, the metal thickness decreases. This causes a change in the eddy current distribution, allowing thinning to be detected through eddy current flaw detection. The amplitude of the eddy current flaw detection signal is related to the thinning ratio, which can be quantified in advance using a test piece. By creating artificial defects (depth / wall thickness) of the inspection object, the corrosion depth can be quantified based on the detected amplitude.

[0051] In this embodiment, three eddy current flaw detectors are arranged along the width of the moving part (here, the self-propelled trolley 1). Here, the width direction of the moving part is defined as being in the same plane and perpendicular to the travel direction of the self-propelled trolley 1. This allows for the measurement of a wider range compared to a single eddy current flaw detector by arranging multiple eddy current flaw detectors along the width direction, which is preferable. The size of each individual eddy current flaw detector can be appropriately set. On the other hand, if the eddy current flaw detector becomes larger compared to point-like thinning, there is a tendency for sensitivity to decrease. Therefore, using multiple probes without increasing the size of a single eddy current flaw detector maintains sensitivity, expands the measurement range, and also shortens the measurement time, which is preferable. However, if the number of eddy current flaw detectors is excessively increased, the moving part becomes large, leading to difficulties in operating the entire inspection device including the moving part, and increasing the complexity of the inspection object and the contour structure of the eddy current flaw detector. Therefore, this needs to be considered.

[0052] Electromagnetic ultrasonic thickness gauge

[0053] The electromagnetic ultrasonic thickness gauge 3 consists of a coil and a magnet. Ultrasonic waves are induced in the inspected component by the interaction between the magnetic field applied by the magnet, which is a conductor, and the eddy currents generated in the inspected component due to the application of a current pulse to the coil, which is also brought close. Permanent magnets or electromagnets can be used to apply the magnetic field to the inspected component. When mounted on a self-propelled trolley 1, rare-earth magnets (permanent magnets) such as neodymium magnets are preferred from a weight perspective.

[0054] When using a permanent magnet, it is brought within a few millimeters (approximately 1-5 mm or less) of the component being inspected and a magnetic field is applied. A coil is then positioned within the area of ​​the applied magnetic field, and a single or multiple pulses of current, approximately 100 kHz to 5 MHz, are applied. This induces eddy currents on the surface of the component being inspected, opposite the coil. These eddy currents interact with the static magnetic field applied by the magnet, generating a Lorentz force within the component. As a result, ultrasonic waves of the same frequency as the applied current are generated and propagate within the component being inspected. The ultrasonic vibrations generated on the surface propagate within the component and return to the surface, causing surface vibration.

[0055] Signal detection can be performed via a coil, acting as the reverse process, thus the transmitting and receiving probes can be the same. The detected signal is amplified appropriately by a preamplifier, then converted to an analog-to-digital converter and input to a computer or microcomputer. After appropriate averaging (noise removal) based on synchronous accumulation, the propagation time of the ultrasonic wave is calculated. When used as a thickness gauge, the time difference between reflections occurring between the surface and bottom of the object being measured is calculated, and multiplied by the known speed of sound to obtain the plate thickness. For example, the speed of sound for steel can be set to approximately 3240 m / s (for transverse waves). The speed of sound can be appropriately corrected for by the steel type and alloy composition.

[0056] Electromagnetic ultrasonic waves are generated by eddy currents induced by coils and static magnetic fields applied by magnets, etc., so they can be used even without close contact with the object being measured. Furthermore, thickness gauges based on electromagnetic ultrasonic waves are stable against changes in probe angle and external interference. Due to these advantages, electromagnetic ultrasonic thickness gauges are very suitable for automating the inspection method and / or inspection apparatus of the present invention.

[0057] The acquired ultrasonic waveforms and plate thickness calculation results are preferably transmitted wirelessly to an external computer, or to the control unit of the self-propelled trolley 1 and eddy current flaw detector 2, for recording and storage. These results are then combined with the flaw detection results from the eddy current testing and the trolley's movement results (position, attitude, etc.) to form the plate thickness measurement results.

[0058] Furthermore, in describing this invention, an electromagnetic ultrasonic thickness gauge is used as an example. This is because, as mentioned above, electromagnetic ultrasonic thickness gauges are relatively easy to operate. However, the effects of this invention can also be achieved with ultrasonic thickness gauges other than electromagnetic ones. In this case, it is only necessary to flow a suitable medium between the component being inspected and the ultrasonic thickness gauge. For example, water or ultrasonic gel can be applied or placed on the component to be inspected, and then the thickness of the component can be measured using an ultrasonic thickness gauge.

[0059] Example

[0060] In this embodiment, the present invention was used to actually inspect piping exhibiting corrosion and thinning. For example... Figure 4 As shown in (a), the outer quarter circumference of pipe P was inspected from the bottom to the side using a self-propelled trolley. The original wall thickness of the pipe was 10 mm. Aluminum strips (conductive strips) were attached to two intact areas to simulate cracks. Furthermore, it was known beforehand that the pitted thinning areas caused by corrosion at the bottom of the pipe were adjacent to the uniformly thinned areas. An E-type coil was used as the eddy current flaw detector 2, configured to take differential detection signals along the travel direction of the self-propelled trolley 1. The E-type coil had a pole spacing of 20 mm, 200 turns, an excitation frequency of 10 kHz, and a lift-off of 3 mm. Three channels of the E-type coil were arranged at 30 mm intervals along the width of the self-propelled trolley 1, and the channel was switched for measurement every 100 ms. The E-type coil was powered by a battery. AD conversion of the detection signal was performed within each E-type coil, and the detection signal was transmitted, recorded, and judged wirelessly to an external computer (an "information processing device") every 100 ms. On the other hand, the measurements of the electromagnetic ultrasonic thickness gauge were summarized at 100mm intervals, and the dispersion (±1σ) within the ±50mm range was calculated as an error bar.

[0061] Figure 4 (b) represents the measurement result. For example... Figure 4 As shown in (b), the amplitude of the eddy current testing signal decreases in intact areas. In contrast, the amplitude of the eddy current testing signal increases in the simulated scratch area and near the bottom of the pipe, clearly indicating a change in the pipe wall thickness. On the other hand, the measurement value of the electromagnetic ultrasonic thickness gauge in intact areas represents an original wall thickness of around 10 mm, with small dispersion. In contrast, near the bottom of the pipe, the measurement value of the electromagnetic ultrasonic thickness gauge represents a wall thickness thinner than the original wall thickness, and its dispersion increases. Based on these findings, it was determined that there is a simulated scratch with a crack on the side of the pipe, point-like thinning near the bottom of the pipe, and uniform thinning adjacent to it; the pipe is intact except for these two locations. Thus, it is confirmed that, according to the present invention, defective locations in pipes can be detected with high precision.

[0062] The embodiments of the invention made by the inventors have been described above. This invention is not limited to the descriptions and drawings that form part of this disclosure based on the embodiments. That is, all other embodiments, examples, and techniques applied based on these embodiments by those skilled in the art are included within the scope of this invention.

[0063] Industrial availability

[0064] According to the present invention, an inspection method and inspection apparatus capable of detecting defects in inspected components with high precision can be provided. Furthermore, according to the present invention, a component repair method can be provided that can suppress the occurrence of failures caused by defects in the components.

[0065] Explanation of reference numerals in the attached figures

[0066] 1 Self-propelled trolley; 1a Drive wheel; 2 Eddy current flaw detector; 3 Electromagnetic ultrasonic thickness gauge; D1 Pit-like defect; D2 V-groove; P Piping; S Steel plate.

Claims

1. An inspection method for detecting defect locations from an inspected component, the inspection method comprising: The first detection step involves using an eddy current flaw detector to detect a first signal from the inspection area on the surface of the component being inspected. The second detection step involves using an ultrasonic thickness gauge to detect a second signal from the inspection area. as well as The determination step involves determining that a defect exists in the inspection area when at least one of the first signal and the second signal indicates an abnormal value.

2. The inspection method according to claim 1, wherein, The determination step includes the following steps: when the first signal indicates an abnormal value and the second signal indicates a normal value, it is determined that there is a crack in the inspection area; when both the first signal and the second signal indicate abnormal values, it is determined that there is point-like thinning in the inspection area; when the first signal indicates a normal value and the second signal indicates an abnormal value, it is determined that there is uniform thinning in the inspection area.

3. A method for repairing a component, comprising a repair step, wherein the repair step repairs or replaces defective parts of the component detected by the inspection method of claim 1 or 2.

4. An inspection device for detecting defects in a component being inspected, the inspection device comprising: An eddy current flaw detector detects a first signal from the inspection area on the surface of the component being inspected; An ultrasonic thickness gauge detects a second signal from the inspection area; as well as The information processing device 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. The inspection device according to claim 4, wherein, have: The moving part moves the eddy current flaw detector and the ultrasonic thickness gauge on the surface of the component being inspected.

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