JP2013002822A - Nondestructive check method and nondestructive check apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nondestructive check method and nondestructive check apparatus in which reliability in an inspection result of a nondestructive check is improved.SOLUTION: A nondestructive check apparatus 100 is configured by installing a guide wave sensor 3 in a part of a tank 10 in a circumferential direction. The guide wave sensor 3 is installed at a first position 3a on the tank 10 and first measurement is performed. Thereafter, the guide wave sensor 3 is installed at a position 3b so as to include a measurement area different from that in the first measurement, and second measurement is performed. Reception signals obtained in the measurements are processed in a signal processing/analysis section 5, a noise signal caused by reflecting a guide wave in a terminal portion in an axial direction is identified, and the presence/absence of a defect in the tank 10 is evaluated.

Description

  The present invention relates to a nondestructive inspection method and a nondestructive inspection apparatus for inspecting presence or absence of a defect generated in a cylindrical member using a guide wave.

  Conventionally, non-destructive inspection using ultrasonic waves has been performed to inspect the presence or absence of defects in cylindrical structures (hereinafter referred to as “cylindrical members”) such as tanks and large-diameter pipes. While the cylindrical member is affected by the surrounding environment, the corrosion progresses from the inner and outer surfaces over time, and the thickness of the cylindrical member decreases. If the corrosion of the cylindrical member progresses, it may cause an accident that leads to leakage or breakage of the contents. For this reason, managers of cylindrical members regularly prevent non-destructive inspections and visual inspections, and maintain the integrity of tanks and piping.

  In the conventional nondestructive inspection using ultrasonic waves, an ultrasonic thickness meter is generally used. However, there are several problems with this ultrasonic thickness meter. One of the problems is that the inspection using the ultrasonic thickness gauge is a one-point inspection that measures the thickness of the contact surface between the sensor and the subject one by one, so the inspection range per time is narrow, Inspection of tanks having a large surface area and piping inspection of large diameters takes a long time, resulting in increased inspection costs. In addition, an inspection using an ultrasonic thickness gauge is not suitable for measurement of places that are difficult for humans to enter, such as measurement of high places or low places and narrow parts of subjects placed in pits. Since countermeasures are taken, it takes time to prepare for the inspection, resulting in an increase in inspection cost.

  In order to cope with such problems of the ultrasonic thickness gauge, a non-destructive inspection using a guide wave which is a kind of ultrasonic wave has been proposed. The guide wave is an ultrasonic wave propagating through an object having a boundary surface such as a pipe or a plate, and has a characteristic of reflecting at a portion where the thickness or shape of the plate changes, that is, the cross-sectional area in the thickness direction changes. Utilizing such characteristics, the guide wave is used when the inner and outer surfaces of pipes and plate-like members are inspected together in a long distance section.

  In the nondestructive inspection apparatus using a guide wave shown in Patent Document 1, a probe group in which a plurality of ultrasonic probes are arranged in the circumferential direction of a cylindrical member that is a subject is arranged in the axial direction of the subject. Two are arranged side by side. The circumferential length of the probe group may be shorter than the entire circumference of the subject. In the nondestructive inspection apparatus of Patent Document 1, the two probe groups are brought into direct contact with the surface of a cylindrical member to propagate a guide wave. In the non-destructive inspection apparatus of Patent Document 1, the probe group only needs to be arranged in a part of the circumferential direction of the subject. Therefore, when inspecting a structure with a long circumference such as a large-diameter pipe or a large tank, It is possible to simplify the number of acoustic probes and sensor devices. Thereby, in the nondestructive inspection apparatus of patent document 1, handling of an ultrasonic probe and a sensor instrument becomes easy, and the cost concerning an inspection can be suppressed low.

  The ultrasonic inspection apparatus and ultrasonic inspection method using a guide wave shown in Patent Document 2 select the number of ultrasonic sensors that transmit a guide wave, and change the drive pattern of the ultrasonic sensor group used for transmission. As a result, the inspection area is widened. For this reason, in the ultrasonic inspection apparatus and the ultrasonic inspection method disclosed in Patent Document 2, the number of measurements until the entire subject is inspected can be reduced, and as a result, the inspection time can be shortened.

JP 2009-109390 A JP 2011-021892 A

  However, in the above-described prior art, reduction of noise generated during transmission / reception of a guide wave has been studied. However, noise due to reflection of the guide wave has not been sufficiently studied as an example. It is done. In non-destructive inspection using guide waves, the single-mode guide waves used in the inspection are partially reflected at the part where the shape has changed, and most of them propagate in the transmission direction as a single mode. Go.

  Here, in a cylindrical member having an end (including a welded flange) such as a large-diameter pipe or tank, total reflection of the guide wave occurs at the end, and the reflected wave propagates in the direction opposite to the transmission direction. . When such total reflection occurs, mode conversion occurs in a part of the single mode guide wave. The mode-converted guide wave is received as a noise signal (pseudo signal) because the propagation speed is different from that of the single-mode guide wave. This noise signal may cause an erroneous determination in the presence or absence of the subject and soundness evaluation, thereby reducing the reliability of the inspection result.

  Then, this invention makes it a subject to provide the nondestructive inspection method and nondestructive inspection apparatus which improve the reliability of the inspection result of a nondestructive inspection.

  In order to solve such a problem, the present invention installs a guide wave sensor in a part of the circumferential direction of the cylindrical member, and transmits a guide wave toward the axial end of the cylindrical member. A nondestructive inspection method for inspecting the cylindrical member for defects using a reflected signal of the guide wave, wherein the guide wave sensor is used to transmit the guide wave and the reflected signal to the cylindrical member. A first measurement step for receiving and a second for transmitting the guide wave and receiving the reflected signal by the guide wave sensor from a position including a measurement region different from the measurement region in the first measurement step. And the reflected signal received in the first measuring step and the second measuring step, respectively, to identify a noise signal generated by the reflection of the guide wave at the end in the axial direction. A detection step of detecting a defect of the cylindrical member based on the separate step, the identification result in the identification step, and the reflected signals respectively received in the first measurement step and the second measurement step; , Including.

  In addition, the present invention is installed on a part of the cylindrical member in the circumferential direction, and transmits a guide wave to the axial end of the cylindrical member and receives a reflected signal of the guide wave on the cylindrical member. Noise generated by reflection of the guide wave at the end in the axial direction using a guide wave sensor that performs a different range a plurality of times as a measurement area and a plurality of the reflected signals that are received by the guide wave sensor and that have different measurement areas Detection for detecting a defect in the cylindrical member based on an identification means for identifying a signal, an identification result by the identification means, and a plurality of the reflected signals having different measurement areas received by the guide wave sensor And means.

  According to the nondestructive inspection method and the nondestructive inspection apparatus according to the present invention, it is possible to determine a noise signal due to a guide wave that has undergone mode conversion by total reflection, and to improve the reliability of the inspection result of the nondestructive inspection. .

1 is an explanatory diagram illustrating a configuration of a nondestructive inspection apparatus according to a first embodiment. It is a flowchart which shows the procedure of the test | inspection using a nondestructive inspection apparatus. It is explanatory drawing explaining the movement to the axial direction of a guide wave sensor. It is a figure which shows an example of the measurement waveform measured by moving the guide wave sensor in the circumferential direction. It is a figure which shows an example of the measurement waveform measured by moving the guide wave sensor in the circumferential direction. It is a figure which shows an example of the measurement waveform measured by moving a guide wave sensor to an axial direction. It is explanatory drawing which shows the structure of the nondestructive inspection apparatus concerning Embodiment 2. FIG. It is a flowchart which shows the procedure of the test | inspection using a nondestructive inspection apparatus.

  Exemplary embodiments of a nondestructive inspection method and a nondestructive inspection apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment 1)
FIG. 1 is an explanatory diagram of a configuration of the nondestructive inspection apparatus according to the first embodiment. FIG. 1 and the subsequent description show an example in which the nondestructive inspection apparatus 100 inspects the presence or absence of a defect in the tank 10 that is the subject. In FIG. 1, the body portion of the tank 10 is shown, and the end plate is not shown (the same applies to FIGS. 3 and 7 described later). In the following description, the term “circumferential direction” or “axial direction” refers to the circumferential direction or axial direction of the tank 10.
Although the nondestructive inspection apparatus 100 is described as the guide wave sensor 3 installed on the outer periphery of the body portion of the tank 10, it may be installed on the inner periphery of the body portion of the tank 10.

  The nondestructive inspection apparatus 100 includes a guide wave sensor 3, a signal transmission / reception unit 4, a signal processing / analysis unit 5, a control unit 6, an input unit 7, and an output unit 8.

  The guide wave sensor 3 includes a first guide wave sensor group 1 and a second guide wave sensor group 2 in which a plurality of ultrasonic sensor terminals (hereinafter referred to as “sensor terminals”) are arranged at equal intervals. The first guide wave sensor group 1 and the second guide wave sensor group 2 have the same configuration and are arranged in parallel to each other. More specifically, the first guide wave sensor group 1 and the second guide wave sensor group 2 have the same number of sensor terminals 1a, 1b, 1c, 1d and 2a, 2b, 2c, 2d connected in parallel, respectively. The signal transmission / reception unit 4 is connected by a cable 9. In FIG. 1, the guide wave sensor 3 is illustrated in a state where it is installed in a tank 10 that is a subject.

  The signal transmitting / receiving unit 4 includes a signal generator, an amplifier, a controller, an A / D converter (all not shown), and the like. The signal generator causes the guide wave sensor 3 to generate a transmission signal for transmitting a guide wave to the subject. The amplifier amplifies the reception signal from the guide wave sensor 3. The controller controls the amplifier. The A / D converter converts a guide wave reception signal, which is an analog signal, into a digital signal.

  The signal processing / analysis unit 5 performs an arithmetic process on the digitized reception signal of the guide wave sensor 3 output from the signal transmission / reception unit 4 and causes the output unit 8 to display the measurement reception waveform on the screen.

  The control unit 6 controls the whole including each part of the nondestructive inspection apparatus 100 based on a command input to the input unit 7 or the like. The control unit 6 includes a storage unit (not shown) that stores various data such as measurement results and received waveforms.

  For example, in FIG. 1, when the guide wave sensor 3 is installed at a position (3 a) indicated by a solid line, a transmission wave 11 a (guide wave) having directivity transmitted from the guide wave sensor 3 is transmitted through the trunk portion of the tank 10. Propagated in the axial direction and reflected at the axial end 13 of the tank 10 on the guide wave transmission direction side (arrow 15a). In FIG. 1, the transmission wave 11a is reflected by the axial end 13 to form a reflected wave 16a. The reflected wave 16 a is received by the guide wave sensor 3, processed by the nondestructive inspection apparatus 100, and then output as a measurement waveform at the output unit 8.

  In addition, a simulated defect 12 is added to the tank 10. When the guide wave sensor 3 is installed at a position including the simulated defect 12 in the measurement region (for example, a position (3b) indicated by a solid line in FIG. 1), a transmission wave 11b having directivity transmitted from the guide wave sensor 3 ( Most of the guide wave propagates in the axial direction in the body portion of the tank 10 (arrow 15b) and is reflected by the axial end portion 13 (reflected wave 16b). A part of the transmission wave 11b is reflected by the simulated defect 12 and propagates to the guide wave sensor 3 side as a defect reflection wave 17b. By identifying this defect reflected wave 17b on the measurement waveform, the presence or absence of a defect in the tank 10 and the position of the defect can be inspected.

  FIG. 2 is a flowchart showing an inspection procedure using the nondestructive inspection apparatus. A guided wave nondestructive inspection procedure using the nondestructive inspection apparatus 100 will be described with reference to FIGS. In the flowchart of FIG. 2, first, the person in charge of inspection or the like installs the guide wave sensor 3 in the tank 10 that is the subject (that is, the position where the first measurement is performed) and the guide wave sensor 3 in the next measurement. The moving direction for moving the image is determined (step S101).

  Here, the moving direction of the guide wave sensor 3 is determined by the shape state of the axial end portion 13 of the tank 10 on the guide wave transmission direction side from the guide wave sensor 3 whose installation position is determined in step S101. More specifically, in the axial end portion 13 of the tank 10, the range in which the guide wave transmitted from the guide wave sensor 3 reaches (this is because the guide wave sensor 3 is moved in parallel in the axial direction from the installation position. Is substantially the same as that of the guide wave sensor 3 in the section longer than the circumferential length of the guide wave sensor 3, the next measurement is performed by changing the installation position of the guide wave sensor 3 from the current installation position in the circumferential direction. (Step S102).

  The movement in the circumferential direction means, for example, moving the guide wave sensor 3 in FIG. 1 from the position 3a to the position 3b (indicated by an arrow 21a). At this time, the portion on the axial end 13 where the guide wave (transmission wave 11b) transmitted at the position 3b after the movement reaches is within the same shape section as the arrival range of the guide wave transmitted at the position 3a. The moving position is determined so that Further, since the guide wave sensor 3 does not move in the axial direction when moving from the position 3a to the position 3b, the distance from the guide wave sensor 3 to the axial end portion 13 at the positions 3a and 3b is as follows. Match. Further, when the guide wave sensor 3 is slightly moved in the axial direction during the movement from the position 3a to the position 3b, as will be described later, the end portion signal of the waveform measured from the position 3a and the waveform measured from the position 3b. The distance is corrected with the end 13 signal.

  On the other hand, in step S <b> 101, in the axial end portion 13 of the tank 10, the range in which the guide wave transmitted from the guide wave sensor 3 reaches has the same shape in a section longer than the circumferential length of the guide wave sensor 3. If not, that is, if the same shape section is less than or equal to the circumferential length of the guide wave sensor 3, the next measurement is performed by moving the installation position of the guide wave sensor 3 in the axial direction from the current installation position. (Step S103). Here, the case where the axial end 13 does not have the same shape is a case where a flange is provided on a part of the axial end 13.

  FIG. 3 is an explanatory diagram for explaining the movement of the guide wave sensor in the axial direction. In FIG. 3, the configuration of the nondestructive inspection apparatus 100 is the same as that in FIG. 1, and thus the same reference numerals are given and detailed description is omitted. To move the guide wave sensor 3 in the axial direction, for example, the guide wave sensor 3 in FIG. 3 is moved from the position 3c to the position 3d (indicated by an arrow 22c). In this case, since the guide wave sensor 3 does not move in the circumferential direction, the guide wave sensor 3 is transmitted at the position where the guide wave (transmitted wave 11c) transmitted at the position 3c reaches and at the position 3d. The portion where the guided wave (transmitted wave 11d, not shown) arrives coincides.

  Returning to the description of FIG. 2, the person in charge of the inspection installs the guide wave sensor 3 at the installation position determined in step S101 (step S104). At this time, it is installed at an accurate position while paying attention to the direction of the guide wave sensor 3 with respect to the axial direction and the circumferential direction of the tank 10. For example, the guide wave sensor 3 is fixed to the installation position of the tank 10 by a suction cup and a magnet (not shown). Further, in the subsequent steps, when the guide wave sensor 3 is moved and installed, the direction of the guide wave sensor 3 with respect to the tank 10 is not changed each time.

  Next, the inspection person in charge connects the guide wave sensor 3 to the signal transmission / reception unit 4 using the signal cable 9, activates the nondestructive inspection apparatus 100, and starts the first measurement (step S105). Specifically, a guide wave is generated by the guide wave sensor 3 and transmitted in the direction of the axial end portion 13 of the tank 10 (arrow 15a). Then, the reflected wave 16 a reflected by the axial end portion 13 is received by the guide wave sensor 3.

  For the measurement, the inspection person starts up a dedicated program for the nondestructive inspection apparatus 100 and inputs measurement condition parameters via the input unit 7. Basic measurement condition parameters may be stored in advance in the nondestructive inspection apparatus 100 and automatically set. In this case, it is preferable that the measurement condition parameter can be changed later. Examples of the measurement conditions include measurement frequency, measurement gain, transmission waveform, applied voltage, noise cut filter, trigger signal timing, and the like.

  When the reflected wave 16a is received by the guide wave sensor 3, the signal transmission / reception unit 4 amplifies and A / D-converts the signals received at the sensor terminals 1a to 2d. Further, the signals received by the signal processing / analyzing unit 5 are combined, and the combined data is subjected to arithmetic processing to generate a measurement waveform as inspection information (step S106). The measured waveform is displayed and output on the output unit 8 by the control unit 6.

  Each graph in FIG. 4 is a diagram illustrating an example of a measurement waveform when the guide wave sensor is moved in the circumferential direction. In FIG. 4, the horizontal axis represents time or distance, and the vertical axis represents relative echo height. Each of the measurement waveforms 31 to 34 represents a reflection signal when a guide wave having a burst waveform with a measurement frequency of 40 kHz is propagated to the tank 10 and transmitted in the direction of the axial end portion 13. The measurement waveform 31 is a measurement waveform measured at the position 3 a in FIG. 1, and the measurement waveform 32 is an enlarged part of the measurement waveform 31. Further, the measurement waveform 33 changes the entire measurement waveform 31 with the scale of the vertical axis (in FIG. 4, the measurement waveform 32 is enlarged with the display range of the measurement waveform 31 in the vertical axis direction being 1/10. This is an enlarged view. Note that the range where the distance from the guide wave sensor 3 is short, that is, the range where the time axis is short is a dead zone region and is excluded from the object of the flaw detection inspection.

  In the measurement waveforms 31 to 33, the end signal Z3 from the axial end 13 is clearly detected. Further, in the measurement waveforms 32 and 33 obtained by enlarging the measurement waveform 31, the signal Y3 is detected in a region before the end signal Z3 (region 14 in FIG. 1). This signal Y3 is a noise signal Y3 (pseudo end signal) generated by partial mode conversion when the single-mode transmission wave 11a (see FIG. 1) is totally reflected by the end 13 in the axial direction. is there. However, even if only the measurement waveforms 31 to 33 are referred to, it is difficult to evaluate whether the noise signal Y3 is a significant signal from a defect or a pseudo end signal generated by reflection.

  Returning to the description of FIG. 2, in order to perform the second measurement, the person in charge of inspection moves the guide wave sensor 3 in the direction determined in step S101 and installs it (step S107). At this time, similarly to step S104, it is installed at an accurate position while paying attention to the direction of the guide wave sensor 3 with respect to the axial direction and the circumferential direction of the tank 10. Then, at the position after the movement, the second measurement is started similarly to step S105 (step S108). In step S108, it is desirable to perform measurement under the same conditions as those in step S105.

  Similarly to step S106, the nondestructive inspection apparatus 100 amplifies and A / D converts the signals received at the sensor terminals 1a, 1b, 1c, 1d and 2a, 2b, 2c, 2d by the signal transmitting / receiving unit 4. To do. Further, the signals received by the signal processing / analysis unit 5 are combined, and the combined data is subjected to arithmetic processing to generate a measurement waveform as inspection information (step S109). The measured waveform is displayed and output on the output unit 8 by the control unit 6.

  A measurement waveform 34 in FIG. 4 is a measurement waveform measured at position 3b in FIG. Note that the vertical scale of the measurement waveform 34 is matched with the measurement waveform 33. As described above, the measurement region of the guide wave sensor 3 at the position 3b includes the simulated defect 12 in the measurement region. For this reason, the transmission wave 11b transmitted from the guide wave sensor 3 is reflected by the simulated defect 12 (see FIG. 1) and the axial end portion 13 (defect reflection wave 17b and end reflection wave 16b). The defect reflected wave 17b and the end reflected wave 16b are received by the guide wave sensor 3 and detected as a defect signal X3 and an end signal Z3, respectively.

  On the other hand, also in the measurement waveform 34, the noise signal Y3 generated by the mode conversion is detected in the region 14 (see FIG. 1) before the end signal Z3. However, it is difficult to evaluate whether or not the noise signal Y3 is a significant signal from the defect or whether it is a pseudo end signal caused by reflection even if only the measured waveform 34 is referred to.

  Returning to the description of FIG. 2, the nondestructive inspection apparatus 100 performs a correction process by the signal processing / analysis unit 5 in order to compare the measurement waveform 33 generated in step S106 and the measurement waveform 34 generated in step S109. And arithmetic processing is performed (step S110). And a measurement result is evaluated using the measured waveform after this process (step S111).

  In step S110, the correction process is performed because the sensitivity of the guide wave signal transmission / reception differs depending on the installation state of the guide wave sensor 3 at the time of measurement, and the installation position and the axial end 13 of the guide wave sensor 3 before and after the movement. This is to correct a slight difference in the distance up to. Specifically, for example, the position and echo height of the axial end portion 13 are obtained from one of the measurement waveforms 33 and 34, and the position and echo height of the axial end portion 13 in the other measurement waveform are corrected. To process comparable waveform information.

  The measurement waveform 35 in FIG. 4 is obtained by performing correction processing and calculation processing (here, difference processing) on the measurement waveforms 33 and 34. In the measurement waveform 35, the noise signal Y3 detected in the measurement waveforms 33 and 34 is canceled and disappears. This is because the noise signal Y3 is caused by a signal that is mode-converted by reflection at the axial end 13 and this signal has a constant propagation velocity under the same measurement conditions. This is because they are detected at the same position or at the same distance. Thus, the noise signal Y3 can be identified as a pseudo end signal resulting from reflection at the axial end 13.

  On the other hand, since the defect signal X3 detected in the measurement waveform 34 remains as a reflected signal as it is, it can be evaluated as a significant signal from the defect. That is, the presence / absence and position of a defect in the tank 10 can be detected from the measurement waveform.

  By such processing, noise signals generated by reflection from the measurement waveform can be removed, and the soundness of the tank 10 can be accurately evaluated. Until the measurement of the entire inspection range is completed (step S112: loop indicated by a solid line), the person in charge of the inspection returns to step S107 and repeats the subsequent processing. If it is necessary to change the moving direction during the measurement, the process returns to step S101 (step S112: loop indicated by a broken line in No), and the subsequent processing is repeated. Then, when the measurement of the entire inspection range this time is finished (step S112: Yes), the processing according to this flowchart is finished.

  By the procedure as described above, the nondestructive inspection apparatus 100 inspects the soundness of the tank 10 that is the subject. The nondestructive inspection apparatus 100 can detect a noise signal caused by total reflection and detect a defect in the tank 10 by comparing measurement waveforms obtained by a plurality of measurements. Here, the process for the measurement waveform will be described in more detail.

  Each graph in FIG. 5 is a diagram illustrating an example of a measurement waveform measured by moving the guide wave sensor in the circumferential direction. In FIG. 5, the horizontal axis indicates time or distance, and the vertical axis indicates relative echo height. A measurement waveform 41 in FIG. 5 is a measurement waveform obtained by measuring an object having defect # 1, defect # 2, and defect # 3 having different distances from the axial end. More specifically, measurement waveforms obtained by moving the guide wave sensor 3 in the circumferential direction of the subject and measuring at three different installation positions are shown as measurement waveforms 42 to 44, respectively.

In the measurement waveform 42, an end signal K from the axial end of the subject, a reflected signal S1 from the defect # 1, and a noise signal N1 (pseudo end signal) that has undergone mode conversion at the axial end are detected. Has been. In the measurement waveform 42, since the reflected signal S1 from the defect and the noise signal N1 are detected at different positions, the two signals can be distinguished.
In the measurement waveform 43, the end signal K, the reflected signal S2 from the defect # 2, and the noise signal N2 (pseudo end signal) that has undergone mode conversion at the end in the axial direction are detected. In the measurement waveform 43, since the reflected signal S2 from the defect and the noise signal N2 are detected at the same position, the two signals cannot be identified.
In the measurement waveform 44, the end signal K, the reflected signal S3 from the defect # 3, and the noise signal N3 (pseudo end signal) that has undergone mode conversion at the end in the axial direction are detected. In the measurement waveform 44, since the reflected signal S3 from the defect and the noise signal N3 are detected at different positions, these two signals can be distinguished.

  When evaluating the presence or absence of a defect in the object, if the reflected signal from the defect and the noise signal (pseudo edge signal) overlap as in the measurement waveform 43, it is necessary to identify these two signals. . In any of the measurement waveforms 42 to 44, it is difficult to evaluate whether the two signals are reflected signals from defects or noise signals from a single measurement waveform.

For this reason, the same arithmetic processing as that in step S110 in FIG. 2 is performed on the plurality of measurement waveforms. The measurement waveform 45 is a measurement waveform obtained by performing the same arithmetic processing as that in step S110 of FIG. 2 on the measurement waveforms 42 to 44.
More specifically, the measurement waveform 46 is a waveform obtained by differentially processing the measurement waveform 42 and the measurement waveform 43. The measurement waveform 47 is a waveform obtained by subjecting the measurement waveform 42 and the measurement waveform 44 to differential processing. The measurement waveform 48 is a waveform obtained by differentially processing the measurement waveform 43 and the measurement waveform 44.

  In each of the measurement waveforms 46 to 48, the noise signals N1 to N3 (pseudo end signals) are canceled and disappear. Further, in the measurement waveform 46, the reflection signal S1 from the defect # 1 and the reflection signal S2 from the defect # 2 can be identified. In the measurement waveform 47, the reflected signal S1 from the defect # 1 and the reflected signal S3 from the defect # 3 can be identified. In the measurement waveform 48, the reflected signal S2 from the defect # 2 and the reflected signal S3 from the defect # 3 can be identified. Furthermore, the position and range of the defect can be detected by comparing the measured waveforms 46 to 48 respectively.

(When moving the guide wave sensor 3 in the axial direction)
In the above description, the case where the guide wave sensor 3 is moved in the circumferential direction (in the case of step S102 in FIG. 1) has been described in detail. However, in the following, the case where the guide wave sensor 3 is moved in the axial direction (FIG. 1). (In the case of step S103) will be described with reference to FIGS.

  Each graph in FIG. 6 is a diagram illustrating an example of a measurement waveform measured by moving the guide wave sensor in the axial direction. In FIG. 6, the horizontal axis indicates time or distance, and the vertical axis indicates relative echo height. Respective measurement waveforms 61 and 62 show reflected signals when a guide wave having a burst waveform with a measurement frequency of 40 kHz is propagated to the tank 10 and transmitted in the direction of the axial end portion 13 (arrows 15c and 15d in FIG. 3). ing.

  The measurement waveform 61 is a measurement waveform measured by installing the guide wave sensor 3 of FIG. 3 at the position 3c. In the measurement waveform 61, an end signal Z6 from the axial end portion 13 and a defect signal X6 from the dummy defect 12 are detected. Further, in the measured waveform 61, the signal Y6 is detected in a region before the end signal Z6 (a portion corresponding to the region 14 in FIG. 5). This signal Y6 is a noise generated by partial mode conversion when the single-mode transmission wave 11c (see FIG. 5) undergoes total reflection at the axial end 13 (see reflected wave 16a, see FIG. 5). This is signal Y6 (pseudo end signal). However, with the measured waveform 61 alone, it is difficult to evaluate whether the noise signal Y3 is a significant signal from a defect or whether it is a pseudo end signal caused by reflection.

  For this reason, the measurement waveform 62 is obtained as a result of measurement by moving the guide wave sensor 3 in the axial direction (arrow 22c in FIG. 5) and installing the guide wave sensor 3 at the position 3d. In the measurement waveform 62, as in the measurement waveform 61, an end signal Z6, a defect signal X6, and a noise signal Y6 are detected. In FIG. 6, in order to facilitate the comparison between the measurement waveform 61 and the measurement waveform 62, the measurement waveform 61 and the measurement waveform 62 are shown such that the positions of the end signals Z <b> 6 on the horizontal axis are the same.

  In the measurement waveform 62, the position of the defect signal X6 based on the end signal Z6 (the distance from the end signal Z6 to the defect signal X6) is the same as that before the movement of the guide wave sensor 3 (measurement waveform 61). Yes. On the other hand, the position of the noise signal Y6 with respect to the end signal Z6 (the distance from the end signal Z6 to the noise signal Y6) differs before and after the movement of the sensor. From this, the defect signal X6 can be identified as a reflected wave due to the simulated defect 12 existing in the tank 10, and the noise signal Y6 can be identified as a pseudo end signal generated by mode conversion.

  Further, in order to compare the measurement waveform 61 and the measurement waveform 62, correction processing and calculation processing are performed (see step S110 in FIG. 2), and the measurement result is evaluated (step S111). The correction processing is performed because the sensitivity of transmission / reception of the guide wave signal differs depending on the installation state of the guide wave sensor 3 at the time of measurement, and the distance between the installation position of the guide wave sensor 3 and the upper end of the tank before and after the movement is different. This is to correct this. A specific method of the correction process is the same as that described in FIG.

  A measurement waveform 63 in FIG. 6 is obtained by performing correction processing and calculation processing (here, addition processing) on the measurement waveforms 61 and 62. In the measurement waveform 63, the noise signal Y6 (pseudo end signal) detected in each of the measurement waveforms 61 and 62 has the same level as the measurement waveform before processing because the distance from the axial end portion 13 is different. It has become. On the other hand, since the defect signal X6 has the same distance from the axial end portion 13, the signal level is increased and displayed with emphasis. Thereby, the noise signal Y6 and the defect signal X6 can be identified from the measurement waveform.

  As described above, according to the nondestructive inspection apparatus 100, it is possible to identify a noise signal generated by mode conversion by total reflection and perform highly accurate nondestructive inspection. Further, according to the non-destructive inspection 100, even if the noise signal and the defect signal from the defect overlap, the noise signal and the defect signal can be separated, so that the defect can be prevented from being overlooked. The reliability of the result can be further improved.

  In addition, according to the nondestructive inspection apparatus 100, it is possible to distinguish between a noise signal and a defect signal, and therefore it is possible to reduce the number of additional inspections and detailed inspections caused by misidentifying the noise signal as a defect signal. The cost and labor required for inspection can be reduced.

(Embodiment 2)
FIG. 7 is an explanatory diagram of a configuration of the nondestructive inspection apparatus according to the second embodiment. In FIG. 7, portions having the same configurations as those of the nondestructive inspection apparatus 100 according to the first embodiment are denoted by the same reference numerals as those in FIG. 1, and detailed description thereof is omitted. In FIG. 7, a nondestructive inspection apparatus 700 according to the second embodiment includes a guide wave sensor 3, a signal transmission / reception unit 4, a signal processing / analysis unit 5, a control unit 6, an input unit 7, and an output unit 8. . The basic functions and operations of these components are the same as those in the first embodiment. Here, the guide wave sensor 3 is composed of eight sensor terminals (sensor terminals 1a, 1b, 1c, 1d, 2a, 2b, 2c, 2d).

  On the other hand, the nondestructive inspection device 700 changes the sensor terminal to be driven among the sensor terminals 1a to 1d and 2a to 2d of the guide wave sensor 3 in a plurality of measurements. Thereby, the measurement result equivalent to moving in the circumferential direction can be obtained without moving the position of the guide wave sensor 3.

  FIG. 8 is a flowchart showing an inspection procedure using the nondestructive inspection apparatus. In the flowchart of FIG. 8, first, the guide wave sensor 3 is installed in the tank 10 that is the subject by a person in charge of inspection or the like (step S201). At this time, it is installed at an accurate position while paying attention to the direction of the guide wave sensor 3 with respect to the axial direction and circumferential direction of the tank 10. The person inspecting the inspection uses the signal cable 9 to connect the guide wave sensor 3 to the signal transmission / reception unit 4 and activates the nondestructive inspection apparatus 700.

  Next, the person in charge of inspection designates the number of sensor terminals 1a to 1d and 2a to 2d of the guide wave sensor 3 used for measurement (step S202). The number is specified by, for example, the inspection person inputting the number into the input unit 7. As a result, the width of the area for transmitting the guide wave in the guide wave sensor 3 is determined, and the switch of the signal transmitting / receiving unit 4 drives the sensor terminals 1a to 1d and 2a to 2d as many as the input number. When performing the measurement twice, the first measurement is performed by driving as many sensor terminals as are sequentially input from one end (for example, the left end) of the guide wave sensor 3. In addition, the sensor terminals are driven by the number of sensors that are sequentially input from the other end (for example, the right end) of the second guide wave sensor 3.

  Specifically, for example, when the number of sensor terminals used for measurement is 4, the first measurement is performed with the sensor terminals 1a, 1b, 2a, 2b located on the left end side of the guide wave sensor 3 as one set. To do. The second measurement is performed with the sensor terminals 1c, 1d, 2c, and 2d positioned on the left end side of the guide wave sensor 3 as one set. As a result, a measurement result equivalent to that obtained by moving the guide wave sensor having a half width in the circumferential direction compared to the guide wave sensor 3 in the circumferential direction can be obtained.

  In addition, the sensor terminal used for two measurements may overlap. For example, assuming that the number of sensor terminals used for measurement is 6, the first measurement is performed at the sensor terminals 1a, 1b, 1c, 2a, 2b, and 2c, and the second measurement is performed at the sensor terminals 1b, 1c, 1d, 2b, and 2c. , 2d may be used.

  Then, the nondestructive inspection apparatus 700 performs the first measurement (step S203). Specifically, when an inspection person inputs a measurement command from the input unit 7 of the nondestructive inspection apparatus 700 (the designated number is four, for example), the control unit 6 of the nondestructive inspection apparatus 700 performs signal processing / A command is sent to the analysis unit 5 and the signal transmission / reception unit 4 to guide a burst waveform having a measurement frequency of, for example, 40 kHz from a specified number of sensor terminals (in this example, sensor terminals 1a, 1b, 2a, 2b). Is transmitted (transmitted wave 11e). This guide wave is transmitted in the direction of the axial end 13 of the tank 10 (arrow 15e), reflected at the axial end 13 and received by the sensor terminal as a reflected wave 16e. If the simulated defect 12 is present in the tank 10, the transmission wave 11e is reflected by the simulated defect 12 and received as a defect reflected wave 17e from the defect.

  When the reflected waves 16e and 17e are received by the guide wave sensor 3, the nondestructive inspection device 700 amplifies and A / D-converts the reflected signals received by the sensor terminals 1a, 1b, 2a, and 2b by the signal transmission / reception unit 4. Further, the signals received by the signal processing / analyzing unit 5 are combined, and the combined data is subjected to arithmetic processing to generate a measurement waveform as inspection information (step S204). The measured waveform is displayed and output on the output unit 8 by the control unit 6.

  Subsequently, the nondestructive inspection apparatus 700 switches the sensor terminal to be driven (step S205) and performs the second measurement (step S206). Also in the second measurement, as in the first measurement, from the designated number of sensor terminals (in this example, sensor terminals 1c, 1d, 2c, 2d) to the axial end 13 direction (arrow 15f). The guide wave is propagated (transmitted wave 11f), and the reflected wave 16f reflected at the axial end 13 is received by the sensor terminal.

  When the reflected wave 16f is received by the guide wave sensor 3, the nondestructive inspection apparatus 700 amplifies and A / D-converts the received reflected signal by the signal transmission / reception unit 4 as in the first measurement. Further, the signals received by the signal processing / analysis unit 5 are combined, and the combined data is subjected to arithmetic processing to generate a measurement waveform as inspection information (step S207). The measured waveform is displayed and output on the output unit 8 by the control unit 6.

  As a result of these two measurements, a measurement waveform such as the measurement waveform 33, 34 in FIG. 4 is obtained by moving the guide wave sensor 3 in the circumferential direction. That is, a measurement result equivalent to that obtained by moving the guide wave sensor 3 from the position 3e to the position 3f in FIG. 7 can be obtained. The nondestructive inspection apparatus 700 performs correction processing and calculation processing in order to compare the measurement waveforms generated in step S207 (step S208). And a measurement result is evaluated using the measured waveform after this process (step S209). Specific processes in steps S208 and S209 are the same as steps S110 and S111 in FIG. By these processes, it is possible to identify a defect signal when the tank 10 is defective and a pseudo end signal.

  Until the measurement of the inspection target range is completed (step S210: No loop), the inspection person moves the guide wave sensor 3 (step S211), returns to step S201, and repeats the subsequent processing. Then, when the measurement of the inspection target range is finished (step S210: Yes), the processing according to this flowchart is finished.

  As described above, in the nondestructive inspection apparatus 700 according to the second embodiment, a measurement result equivalent to moving in the circumferential direction can be obtained without moving the position of the guide wave sensor 3. Thereby, according to the nondestructive inspection apparatus 700, the frequency | count of a movement of the guide wave sensor 3 at the time of a test | inspection can be decreased, and the labor and cost concerning a test | inspection can be reduced.

  Further, according to the nondestructive inspection apparatus 700, as in the nondestructive inspection apparatus 100 according to the first embodiment, it is possible to identify a noise signal generated by mode conversion by total reflection and perform highly accurate nondestructive inspection. it can. In addition, according to the nondestructive inspection apparatus 700, even if the noise signal and the defect signal from the defect overlap, the noise signal and the defect signal can be separated, so that the oversight of the defect can be prevented. The reliability of the inspection result can be further improved.

  In addition, according to the nondestructive inspection apparatus 700, it is possible to distinguish between a noise signal and a defect signal, so that it is possible to reduce the number of additional inspections and detailed inspections caused by misidentifying the noise signal as a defect signal. The cost and labor required for inspection can be reduced.

  The nondestructive inspection method and the nondestructive inspection apparatus according to the present invention are effective when inspecting a cylindrical member having an end, and particularly effective when inspecting for the presence of defects such as large-diameter pipes and tanks. is there.

1 1st guide wave sensor group 1a-1d Sensor terminal (ultrasonic terminal)
2 2nd guide wave sensor group 2a-2d Sensor terminal (ultrasonic terminal)
DESCRIPTION OF SYMBOLS 3 Guide wave sensor 4 Signal transmission / reception part 5 Signal processing and analysis part 6 Control part 7 Input part 8 Output part 9 Signal cable 10 Tank (cylindrical member)
12 Defect 13 Axial end

Claims (5)

A guide wave sensor is installed on a part of the cylindrical member in the circumferential direction, a guide wave is transmitted toward the axial end of the cylindrical member, and a reflected signal of the guide wave is used to A non-destructive inspection method for inspecting for defects,
A first measurement step of transmitting the guide wave and receiving the reflected signal to the cylindrical member by the guide wave sensor;
A second measurement step of transmitting the guide wave and receiving the reflected signal by the guide wave sensor from a position including a measurement region different from the measurement region in the first measurement step;
An identification step of identifying a noise signal generated by reflection of the guide wave at the axial end using the reflected signals respectively received in the first measurement step and the second measurement step;
A detection step of detecting a defect in the cylindrical member based on the identification result in the identification step and the reflected signals respectively received in the first measurement step and the second measurement step;
A non-destructive inspection method characterized by comprising: The guide wave sensor has a predetermined length in the circumferential direction of the cylindrical member, and the second guide wave sensor is shifted from the installation position of the guide wave sensor in the first measurement step. When performing the measurement process,
In the second measurement step, when the portion including the measurement region in the first measurement step in the axial end portion has the same shape section longer than the circumferential length of the guide wave sensor, the current measurement is performed. 2. The method according to claim 1, wherein the guide wave sensor is moved from the installation position in the first measurement step in the circumferential direction so that a measurement region in the same shape section is included in the measurement region. Non-destructive inspection method. The guide wave sensor has a predetermined length in the circumferential direction of the cylindrical member, and the second guide wave sensor is shifted from the installation position of the guide wave sensor in the first measurement step. When performing the measurement process,
In the second measurement step, when the portion including the measurement region in the first measurement step in the axial end portion does not have the same shape section longer than the circumferential length of the guide wave sensor, The guide wave sensor is moved in the axial direction of the cylindrical member from the installation position in the first measurement step so that the measurement region in the measurement of the same coincides with the measurement region in the first measurement step. The nondestructive inspection method according to claim 1. The guide wave sensor is a plurality of ultrasonic terminals arranged in the circumferential direction of the cylindrical member,
The first measurement step is performed using a predetermined number of the ultrasonic terminals in order from one end of the array,
The nondestructive inspection method according to claim 1, wherein the second measurement step is performed using the same number of ultrasonic terminals as the first measurement step in order from the other end of the array. It is installed in a part of the cylindrical member in the circumferential direction, and transmits a guide wave to the axial end of the cylindrical member and receives a reflected signal of the guide wave, using different ranges on the cylindrical member as measurement regions. A guided wave sensor to be performed multiple times,
Identification means for identifying a noise signal generated by reflection of the guide wave at the end in the axial direction, using a plurality of the reflected signals having different measurement areas received by the guide wave sensor;
Detection means for detecting a defect of the cylindrical member based on the identification result by the identification means and the plurality of reflected signals having different measurement areas received by the guide wave sensor;
A nondestructive inspection apparatus comprising:

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