JP6489798B2 - Defect evaluation method and defect evaluation apparatus - Google Patents

Description

  The present invention relates to a defect evaluation method and a defect evaluation apparatus for evaluating defects in a portion embedded in soil or the like in a metal pipe.

  Conventionally, various defect evaluation methods and defect evaluation apparatuses using ultrasonic flaw detection techniques have been proposed in order to evaluate defects in metal pipes embedded in soil or concrete. For example, Patent Document 1 proposes a defect evaluation apparatus, a defect evaluation method, and a program for performing deterioration evaluation without digging up a portion embedded in soil such as a metal pipe (for example, panzer mast).

  In this defect evaluation method, the ultrasonic probe is brought into contact with the surface of the portion exposed to the outside of the metal tube, and the probe oscillates SH waves (Shear Horizontal Wave), that is, in parallel with the surface of the metal tube. Ultrasonic flaw detection is performed by transmitting ultrasonic waves composed of transverse waves along the surface of the metal tube toward the embedded portion of the metal tube. In this defect evaluation method, an image is displayed in A scope format (that is, a graph relating to the beam path length and beam intensity) based on the signal received by the probe, and the defect is evaluated using the image in the A scope format. ing. Specifically, the height of the end echo from the signal waveform shown in the A scope format image (that is, the reflected echo from the lower end of the metal tube when the intensity of the reflected echo from the corroded portion of the metal tube is adjusted to 80%) In addition to (height), parameters such as an angle coefficient and a reference boundary height are obtained, and using these parameters, a defect evaluation (such as the presence or absence of a defect) is performed.

  Similarly to Patent Document 2, in Patent Document 2, an ultrasonic wave is transmitted from the probe toward a portion where the metal tube is embedded, and a reception signal and an embedded signal based on the reflected wave from the lower end of the metal tube are embedded. An A-scope format image is displayed for the received signals from the entire portion, and the intensity of the beam intensity of these received signals is compared to judge the defect.

Japanese Patent No. 3973603 Japanese Patent No. 5519268

  In both of the defect evaluation methods described in Patent Document 1 and Patent Document 2, ultrasonic waves such as SH waves are transmitted from the probe to the embedded portion of the metal tube, and the signal received by the probe is transmitted. Based on this, an image of the beam path length and the beam intensity is displayed in the A scope format, and the defect is evaluated using the image of the A scope format. In the A scope format image, if there is only one defect of the metal tube, it is possible to know the position of the metal tube in the axial direction, but there are a plurality of defects in the embedded portion. In some cases, it is difficult to grasp the position and shape of each defect. In addition, since the SH wave has a property of easily spreading in a direction orthogonal to the traveling direction of the ultrasonic beam (that is, easily spreading radially), the position of the defect in the circumferential direction of the metal tube and the shape of the defect are determined by the A scope. It is particularly difficult to evaluate using only the formatted images.

  In addition, when the embedded part of the metal pipe receives a high pressure from the soil, when the length of the embedded part is long, or when the lower end of the metal pipe corrodes and the shape of the lower end changes, The signal reflected from the lower end of the metal tube becomes unstable, and there is a possibility that the defect cannot be accurately evaluated.

  The present invention has been made in view of the above circumstances, and provides a defect evaluation method and a defect evaluation apparatus capable of accurately grasping the position and shape of a defect in a portion where a metal tube is embedded. For the purpose.

In order to solve the above problems, the defect evaluation method of the present invention is a defect evaluation method for evaluating defects generated in a portion embedded in soil or concrete in a metal tube, wherein the probe is connected to the metal tube. The probe is moved in the circumferential direction of the metal tube while being in contact with the part exposed to the outside, and an ultrasonic wave as a surface SH wave is transmitted from the probe to the buried part, and from the buried part A first scanning image in the B-scope format based on a signal related to the reflected wave received by the probe in the circumferential scanning step, When the probe receives a plurality of reflected waves at one position in the circumferential direction during the first image display step of displaying the first image on the display unit and the circumferential scanning step, at the position The probe The probe is moved in the axial direction of the metal tube, and an ultrasonic wave, which is a surface SH wave, is transmitted from the probe to the embedded portion, and a reflected wave from the embedded portion is received by the probe. A second image in a B-scope format is generated based on an axial scanning step and a signal related to a reflected wave received by the probe in the axial scanning step, and the second image is displayed on the display unit. And a two-image display step .

According to this feature, in the circumferential scanning step, the probe is moved in the circumferential direction of the metal tube, and ultrasonic waves that are surface SH waves are transmitted from the probe to the embedded portion of the metal tube. Here, the surface SH wave is a transverse wave that swings in parallel with the surface of the metal tube and travels along the surface of the metal tube. And the reflected wave from the said embedded part is received with the said probe. Next, in the first image display step, the first image in the B scope format is displayed based on the signal related to the reflected wave received by the probe. Here, the B scope type is a probe in the probe moving direction (in this case, the circumferential direction of the metal tube) and in the ultrasonic wave transmitting direction (in this case, the axial direction of the metal tube). This is a format for displaying the position where the ultrasonic wave is reflected by the two-dimensional coordinates defined by the distance from. In the first image in the B-scope format, it becomes possible to accurately know the circumferential position of the metal tube and the axial position of the metal tube with respect to the defect, and as a result, the defect of the embedded portion of the metal tube. It is possible to accurately grasp the position and shape. Here, the SH wave tends to spread in the direction orthogonal to the traveling direction of the ultrasonic beam. However, as described above, the probe is moved in the circumferential direction of the metal tube to perform circumferential scanning. By displaying the first image in the B scope format based on the obtained reflected wave, it is possible to easily identify the position of the defect in the circumferential direction of the metal tube.
In addition, when the probe receives a single reflected wave at one position in the circumferential direction, it can be easily determined that the defect is a local defect such as a through hole, but a plurality of reflected waves are received. In some cases, it may not be known whether the defect is a crack extending linearly or a corroded part spreading in a planar shape. Therefore, in such a case, in the axial scanning step, the probe is moved in the axial direction of the metal tube, and ultrasonic waves that are surface SH waves are transmitted from the probe to the embedded portion of the metal tube. Then, the reflected wave from the embedded portion is received by the probe. Then, in the second image display step, the second image in the B scope format is displayed based on the signal related to the reflected wave received by the probe. As a result, the circumferential position and the axial position of the defective metal tube can be accurately identified, and the position and shape of the defect can be grasped more clearly.

  Based on the signal obtained by the circumferential scanning step and the signal obtained by the axial scanning step, a B-scope-type thinning map image that displays the position and shape of the defect is created, and the reduction It is preferable to further include a thinning map display step of displaying a meat map image on the display unit.

  According to this feature, the thinning map image in the B scope format is created based on the signal obtained by the circumferential scanning step and the signal obtained by the axial scanning step. By using the first image and the second image together to evaluate the defect, it is possible to grasp the position and shape of the defect more accurately.

  In the circumferential scanning step, it is preferable that the probe is continuously moved at a constant speed in the circumferential direction.

  When the circumferential scanning is performed using the surface SH wave, the received signal tends to become unstable if the flaw detector is stopped halfway. Therefore, if the flaw detector is continuously moved at a constant speed, it is possible to stabilize the received signal and maintain an accurate grasp of the position and shape of the defect.

  Here, in order to transmit the SH wave to the metal tube to be inspected, it is necessary to increase the viscosity of the contact medium interposed between the probe and the metal tube, but if the viscosity increases, the ultrasonic beam There is a problem that it takes time to stabilize the transmission / reception of the probe and a problem that the scanning performance of the probe is deteriorated. However, these problems can be solved by moving the flaw detector continuously at a constant speed as described above.

  It is preferable that the probe includes a transmission probe that transmits the surface SH wave to the embedded portion and a reception probe that receives a reflected wave from the embedded portion.

  According to such a feature, by using two probes for transmission and reception as the probes, it is possible to prevent the occurrence of a non-measurable region, that is, a surface dead zone at a position close to the probe. Is possible.

  In the first image display step, it is preferable that the first image is generated by performing aperture synthesis processing on a plurality of signals related to reflected waves received at a plurality of positions in the circumferential direction in the circumferential scanning step.

  According to such a feature, the same signal as when a probe having a large aperture width transmits / receives an ultrasonic wave is obtained by performing aperture synthesis processing on signals related to reflected waves received at a plurality of positions in the circumferential direction. Thus, the position and shape of the defect can be grasped more accurately.

  It is preferable that the method further includes a defect evaluation step of evaluating the defect based on at least the first image.

  According to this feature, it is possible to accurately grasp the position and shape of the defect and accurately evaluate the defect by evaluating the defect using at least the first image.

The defect evaluation apparatus of the present invention is a defect evaluation apparatus for evaluating defects generated in a portion embedded in soil or concrete in a metal pipe, and can transmit ultrasonic waves that are surface SH waves. A probe for receiving a reflected wave from the embedded portion by ultrasonic waves transmitted in contact with an externally exposed portion of the tube, and a circumferential direction for guiding the probe in the circumferential direction of the metal tube A B-scope type image is generated based on a guide unit , a guide unit having an axial guide unit for guiding the probe in the axial direction of the metal tube, and a signal related to a reflected wave received by the probe. And a display unit for displaying the image.

According to this feature, the probe is moved in the circumferential direction while guiding the probe in the circumferential direction of the metal tube by the circumferential guide portion, and the surface SH is moved from the probe to the portion where the metal tube is embedded. An ultrasonic wave that is a wave is transmitted, and the probe receives a reflected wave from the embedded portion. And a display part displays the image (above-mentioned 1st image) of the B scope format about the circumferential direction based on the signal regarding the reflected wave received with the probe. Thus, the operator can accurately know the circumferential position of the metal tube and the axial position of the metal tube with respect to the defect. As a result, it is possible to accurately grasp the position and shape of the defect in the embedded portion of the metal tube.
In the above feature, the guide portion further includes an axial guide portion that guides the probe in the axial direction of the metal tube. For this reason, the probe is moved in the axial direction while guiding the probe in the axial direction of the metal tube by the axial direction guide portion, and the surface SH wave is super-wave from the probe to the embedded portion of the metal tube. A sound wave is transmitted and the probe receives a reflected wave from the embedded portion. And a display part displays the image (above-mentioned 2nd image) of a B scope format about an axial direction based on the signal regarding the reflected wave received with the probe. Thereby, the operator sees the image of the B scope format in the circumferential direction (the first image described above) and the image of the B scope format in the axial direction (the second image described above), so that the metal tube about the defect is obtained. It becomes possible to know the position in the circumferential direction and the position in the axial direction of the metal tube more accurately. As a result, it is possible to more accurately grasp the position and shape of the defect in the embedded portion of the metal tube.

  A thinning map creating unit that creates a thinning map for displaying the defect in a two-dimensional coordinate of the circumferential distance and the axial distance based on a signal related to the reflected wave received by the probe. The display unit preferably displays the thinning map. In this case, the operator can know the position in the circumferential direction and the position in the axial direction of the metal tube about the defect more accurately by looking at the thinning map displayed on the display unit. As a result, it is possible to more accurately grasp the position and shape of the defect in the embedded portion of the metal tube.

  It is preferable to further include a thinning area evaluation unit that evaluates the area of the defect displayed on the thinning map. In this case, the defect area can be accurately evaluated.

  It is preferable that the guide unit includes a movement amount detection unit that detects a movement amount of the probe.

  According to this feature, it is possible to more accurately grasp the position and shape of the defect in the portion where the metal tube is embedded by detecting the movement amount of the probe by the movement amount detection means.

  As described above, according to the defect evaluation method and the defect evaluation apparatus of the present invention, it is possible to accurately grasp the position and shape of the defect in the embedded portion of the metal tube.

It is a figure which shows the whole structure of the defect evaluation apparatus which concerns on embodiment of this invention. It is a front view of the circumferential direction guide part which guides the probe of FIG. 1 and the said probe to the circumferential direction of a metal tube. FIG. 3 is a plan view of the probe and the circumferential guide portion of FIG. 2. It is a left view of the probe and circumferential direction guide part of FIG. FIG. 3 is a cross-sectional explanatory view showing a state in which the probe and the circumferential guide portion of FIG. 2 are attached to the peripheral surface of the metal tube. It is a top view of the axial direction guide part which guides the probe of FIG. 1 and the said probe to the axial direction of a metal tube. It is a block diagram which shows the internal structure of the analysis part of FIG. It is a figure which shows the state which transmits an ultrasonic wave with respect to the defect which the probe of FIG. 1 consists of a crack. (A) is a diagram showing a state in which the probe in FIG. 1 moves in the circumferential direction of the metal tube and emits ultrasonic waves to a defect consisting of cracks to perform circumferential scanning, and (b) in FIG. It is a figure which shows the 1st image of a B scope format obtained by the circumferential scanning of a). It is a figure which shows the state which the probe of FIG. 1 transmits an ultrasonic wave with respect to the local defect which consists of a through-hole. (A) is the figure which shows the state which is transmitting the ultrasonic wave with respect to the local defect which consists of a through-hole while the probe of FIG. 1 moves to the circumferential direction of a metal tube, and is performing circumferential scanning. b) is a first image in the B scope format obtained by the circumferential scanning in (a). It is a figure which shows the state which transmits the ultrasonic wave with respect to the defect which consists of the corrosion part which the probe of FIG. 1 generate | occur | produced in the whole circumferential direction of the metal tube. (A) is a diagram showing a state in which the probe in FIG. 1 moves in the circumferential direction of the metal tube and emits ultrasonic waves to a defect consisting of a corroded portion to perform circumferential scanning, and (b) in FIG. It is a figure which shows the figure which shows the 1st image of B scope format obtained by the circumferential direction scanning of (a), and the image of A scope format which shows beam intensity. It is a figure which shows the state which is transmitting the ultrasonic wave with respect to the defect which consists of a corrosion part, and is scanning an axial direction, while the probe of FIG. 1 moves to the axial direction of a metal tube. It is a figure which shows the 2nd image of a B scope format obtained by the axial direction scanning of FIG. It is a flowchart which shows the first half part of the procedure of the defect evaluation method of this invention. It is a flowchart which shows the latter half part of the procedure of the defect evaluation method of this invention. It is a figure which shows the 1st image of a B scope format used in order to investigate the presence or absence of a defect signal in the defect evaluation method of this invention. It is a figure which shows the image of A scope format used in order to investigate whether the signal level of a defect signal is more than a threshold value in the defect evaluation method of this invention. It is a figure which shows the 2nd image of a B scope format used in order to determine the thinning length of an axial direction in the defect evaluation method of this invention. It is a figure which shows the thinning map image of a B scope format produced in the thinning map creation process in the defect evaluation method of this invention. It is a section explanatory view showing an example of a guide part provided with a movement mechanism for moving a peripheral direction guide part in the peripheral direction as a modification of the defect evaluation device of the present invention. It is a block diagram which shows the preservation | save part further provided with the signal detection part and the alerting | reporting part as another modification of the defect evaluation apparatus of this invention.

  Hereinafter, embodiments of the defect evaluation method and the defect evaluation apparatus of the present invention will be described in more detail with reference to the drawings.

  A defect evaluation apparatus 1 shown in FIG. 1 is an apparatus that evaluates a defect C generated in a portion B embedded in the soil G in a metal pipe P. The metal pipe P to be inspected is a metal cylindrical body made of, for example, a steel having a smooth shape with little unevenness on the peripheral surface, and specifically has a cylindrical shape.

  The defect evaluation apparatus 1 includes a probe 3 that transmits and receives ultrasonic waves 101, a guide unit 4 that guides the probe 3 in the circumferential direction X and the axial direction Y of the metal tube P, and the probe 3. A storage unit 5 that stores the obtained signal data, a display unit 7 that displays various images based on the obtained signal data, and an analysis unit 6 that evaluates the defect C are provided.

  The probe 3 can transmit ultrasonic waves that are surface SH waves, and can also transmit reflected waves from the embedded portion B by the ultrasonic waves that are transmitted in contact with the exposed portions of the metal pipe P. It has a configuration for receiving. Specifically, the probe 3 receives the transmission probe 8 that transmits the ultrasonic wave 101 that is the surface SH wave to the embedded portion B and the reflected wave 103 from the embedded portion B. And a probe 9 for use. The transmitting probe 8 and the receiving probe 9 are in contact with the surface exposed to the outside of the metal tube P via a viscous adhesive material in a state of being arranged in the circumferential direction X of the metal tube P. Be placed. The transmitting probe 8 transmits an ultrasonic wave 101 that is a surface SH wave toward a portion B embedded along the axial direction Y of the metal tube P. The ultrasonic wave 101 that is a surface SH wave travels along the surface of the metal tube P while amplitude is parallel to the surface of the metal tube P. Since the probe 3 includes the transmission probe 8 and the reception probe 9 described above, the ultrasonic wave 101 that is a surface SH wave is in contact with an externally exposed portion of the metal tube P. Can be transmitted to the embedded part B, and the reflected wave 103 from the embedded part B can be received. When the embedded portion B has a defect C, the ultrasonic wave is reflected by the defect C before reaching the lower end of the metal tube P, so that the reflected wave 102 from the defect C is received by the probe 3. .

  The guide part 4 has the circumferential direction guide part 11 shown by FIGS. 2-4, and the axial direction guide part 12 shown by FIG.

  2 to 4 guide the probe 3 in the circumferential direction X of the metal tube P. As shown in FIG. The circumferential guide 11 includes a screw 13 fixed to the upper surface of each of the transmission probe 8 and the reception probe 9 of the probe 3, a nut 14 screwed into these screws 13, A spring 16 disposed around each screw 13, a fixing jig 17 that supports the probe 3 via the screw 13 and the nut 14, a plurality of wheels 18, a magnet 19, and a rotary encoder 20 are provided. ing.

  The fixing jig 17 is disposed so as to be spaced apart above the two pedestal portions 17a, a plurality of support columns 17b standing on the upper surface of each pedestal portion 17a, and above each pedestal portion 17a. And a fixed upper plate 17c. Each pedestal portion 17a has a lower surface opening that allows the transmitting probe 8 or the receiving probe 9 to descend.

  The two pedestals 17a are arranged side by side in the circumferential direction X. The two pedestals 17a are rotatably connected around the rotation axis Q by pins (not shown) arranged along the rotation axis Q extending in parallel with the axial direction Y. As a result, as shown in FIG. 5, when the two pedestals 17 a are arranged on the outer peripheral surface of the metal tube P, the two pedestal portions 17 a are inclined with respect to each other about the rotation axis Q and approach the outer peripheral surface of the metal tube P Placed in position.

  A plurality of wheels 18 are arranged side by side in the circumferential direction X on the side surface facing the axial direction Y of the two pedestals 17a connected. Thereby, the fixing jig 17 is guided in the circumferential direction X by the plurality of wheels 18.

  Magnets 19 are fixed to the side surfaces of the pedestal portions 17a facing the axial direction Y, respectively. The lower surface of the magnet 19 is arranged at the same height as the position of the lowermost end of the wheel 18 or at a slightly higher position. In a state where the wheel 18 is in contact with the outer peripheral surface of the metal tube P, the magnet 19 attracts the probe 3 and the circumferential guide portion 11 on the outer peripheral surface of the metal tube P by being attracted to the outer peripheral surface of the metal tube P. It is possible to hold it.

  Since the upper plate 17c is fixed in the vicinity of the upper end portion of the column 17b, it does not move up and down. The upper plate 17c has a through hole (not shown) through which the upper end of the screw 13 passes. The nut 14 is in contact with the upper surface of the upper plate 17c in a state of being screwed to the upper end portion of the screw 13. Since the lowering of the nut 14 is restricted by the upper plate 17c, when the nut 14 rotates to the right, the screw 13 that engages with the nut 14 rises, and when the nut 14 rotates to the left, the screw 13 lowers. To do.

  A spring 16 is arranged in a compressed state between the lower surface of the upper plate 17c and the upper surface of the transmitting probe 8 or the receiving probe 9. That is, the upper end of the spring 16 is in contact with the upper plate 17c that is fixed to the support column 17b and cannot move up and down, while the lower end of the spring 16 contacts the upper surface of the transmitting probe 8 or the receiving probe 9. It touches. Therefore, the transmission probe 8 or the reception probe 9 is always pressed downward by the spring 16.

  The urging force applied to the probe 3 (transmitting probe 8 or receiving probe 9) by the spring 16 is the force that the magnet 19 attracts to the metal tube P so that the magnet 19 does not separate from the metal tube P. Is adjusted to be lower.

  The rotary encoder 20 is attached to the surface of the pedestal portion 17a of the fixing jig 17 facing the circumferential direction X. Thereby, the rotary encoder 20 functions as a movement amount detecting means for detecting the movement amount in the circumferential direction X of the probe 3 and the circumferential direction guide portion 11.

  The axial guide 12 shown in FIG. 6 is configured to guide the probe 3 in the axial direction Y of the metal tube P. Specifically, the axial direction guide part 12 has a configuration in which the directions of the wheels 18 and the rotary encoder 20 of the circumferential direction guide part 11 shown in FIG. 3 are changed from the circumferential direction X to the axial direction Y by 90 degrees. More specifically, the axial guide portion 12 is similar to the circumferential guide portion 11 in that the screw 13, the nut 14, the spring 16, the fixing jig 17, the plurality of wheels 18, the magnet 19, And a rotary encoder 20. The plurality of wheels 18 are arranged side by side in the axial direction Y on the side surfaces facing the circumferential direction X of the two pedestals 17 a of the fixing jig 17 connected to each other. Thereby, the fixing jig 17 is guided in the axial direction Y by the plurality of wheels 18. The rotary encoder-20 is attached to the side surface of the pedestal portion 17a of the fixing jig 17 facing the axial direction Y. As a result, in the axial direction guide portion 12, the fixing jig 17 is guided in the axial direction Y by the plurality of wheels 18. The rotary encoder 20 can detect the amount of movement of the probe 3 and the circumferential guide portion 11 in the axial direction Y.

  Here, the screw 13, the nut 14, and the spring 16 are shared by both the circumferential guide 11 and the axial guide 12. Therefore, by attaching the probe 3 together with the screw 13, the nut 14, and the spring 16 to the fixing jig 17 of either the circumferential guide portion 11 or the axial guide portion 12, the single probe 3 Circumferential scanning and axial scanning can be performed. In addition, you may make the circumferential direction guide part 11 and the axial direction guide part 12 into the respectively independent structure without sharing the screw 13, the nut 14, and the spring 16 as mentioned above.

  Since the guide part 4 has the circumferential guide part 11 shown in FIGS. 2 to 4 and the axial guide part 12 shown in FIG. 6 as described above, the probe 3 is placed around the metal tube P. It is possible to guide in the direction X and the axial direction Y.

  As shown in FIG. 1, the storage unit 5 includes a memory 21 that stores signal data obtained by the probe 3.

  The display unit 7 generates an image in the B scope format based on a signal related to the reflected wave 103 received by the probe 3, and displays the image. The B-scope format image includes the position of the probe 3 in the moving direction (scanning direction) of the probe 3 (for example, the circumferential direction X of the metal tube P in the case of circumferential scanning) and the transmission direction of the ultrasonic wave 101 ( That is, it is an image in a format that displays the position where the ultrasonic wave 101 is reflected by the two-dimensional coordinates defined by the distance from the probe 3 in the axial direction Y) of the metal tube P.

  For example, as shown in FIG. 8 and FIG. 9A, the defects C1 to C4 formed by cracks while the probe 3 moves in the circumferential direction X of the metal tube P (each length is 20 mm, 30 mm, 40 mm). 10 mm and formed at positions 90 degrees apart from each other), when the circumferential scanning is performed by transmitting the ultrasonic wave 101, as shown in FIG. A first image in the B scope format in the scanning direction (X-axis direction) of the child 3 and the direction in which the ultrasonic wave 101 propagates (Y-axis direction) is displayed on the display unit 7. In the first image in the B scope format shown in FIG. 9B, the ultrasonic wave propagation direction (Y-axis direction) at positions corresponding to the upper end 51 and the lower end 52 of the defects C1 to C4 formed by cracks in FIG. 9A. ) Displays two waveforms 53 and 54 that are separated from each other. These waveforms 53 and 54 are represented in an upwardly convex arc shape. This has a shape corresponding to the distance between the probe 3 and the upper end 51 and the lower end 52 of the defects C1 to C4 continuously changing when the probe 3 moves in the circumferential direction. Therefore, when the probe 3 is located immediately above each of the defects C1 to C4, the distance between the probe 3 and the upper end 51 and the lower end 52 of each of the defects C1 to C4 is the smallest. The vertices of the waveforms 53 and 54 are displayed.

  Further, as shown in FIG. 10 and FIG. 11 (a), local defects C5 to C8 (each having a diameter of 1 mm, consisting of through holes) while the probe 3 moves in the circumferential direction X of the metal tube P. 11 (b), 2 mm, 4 mm, and 8 mm, which are formed at positions 90 degrees apart from each other), when the circumferential scanning is performed by transmitting the ultrasonic wave 101, as shown in FIG. The first image in the B scope format in the scanning direction (X-axis direction) of the probe 3 and the direction in which the ultrasonic wave 101 propagates (Y-axis direction) is displayed on the display unit 7. In the first image in the B scope format shown in FIG. 11B, one waveform 55 is displayed at each of the positions corresponding to the defects C5 to C8 formed of the through holes in FIG.

  Further, as shown in FIG. 12 and FIG. 13A, a defect C9 (width) formed by a corroded portion that occurs in the entire circumferential direction of the metal tube P while the probe 3 moves in the circumferential direction X of the metal tube P. 10 mm), the scanning direction (X-axis direction) of the probe 3 and the ultrasonic wave 101 are scanned as shown in FIG. 13B. A first image 58 in the B scope format in the propagation direction (Y-axis direction) is displayed on the display unit 7. In the first image 58 in the B scope format shown in FIG. 13B, not only the positions corresponding to the upper end 56 and the lower end 57 of the defect C9 made of the corroded portion in FIG. It can be seen that the position and shape of the defect C9 made of the corroded portion cannot be specified. Further, even if the A-scope-type image 59 shown in FIG. 13B (that is, a graph relating to the ultrasonic propagation direction (Y-axis direction) and the beam intensity) is viewed, the position of the defect C9 in the Y-axis direction cannot be specified. I understand that.

  Therefore, in such a case, axial scanning is performed. As shown in FIG. 14, while the probe 3 moved upward along the axial direction Y of the metal tube P, the ultrasonic wave 101 was transmitted to the defect C9 formed of the corroded portion, and the axial scanning was performed. In this case, as shown in FIG. 15, the position of the probe 3 in the scanning direction (Y-axis direction) of the probe 3 and the probe 3 in the direction in which the ultrasonic wave 101 propagates (Y-axis direction). A second image in the B scope format defined by the distance is displayed on the display unit 7. In the second image shown in FIG. 15, as the probe 3 shown in FIG. 14 scans in the axial direction Y, the distance (that is, the beam path) between the probe 3 and the defect C9 becomes longer. Of the waveform 60 of the signal due to reflection from the defect C9 consisting of the corroded portion, the signal waveforms 61 and 62 reflected at the upper end 56 and the lower end 57 of the corroded portion C9 are directed in the probe scanning direction (Y-axis direction). Therefore, it is clearly displayed in a right-downward shape increasing in the ultrasonic wave propagation direction (Y-axis direction), so that it can be easily distinguished from a signal waveform caused by reflection from other parts. Thereby, it is possible to specify the position and shape of the defect C9 which consists of a corrosion part.

  As shown in FIG. 7, the analysis unit 6 includes a defect signal detection unit 24, a thinning length determination unit 25, a thinning map creation unit 26, and a thinning area analysis evaluation unit 27.

  The defect signal detector 24 detects a defect signal from signals obtained by circumferential scanning. For example, the defect signal detection unit 24 detects a signal (that is, a defect signal) 104 corresponding to a reflected wave from the defect in the first image in the B scope format (for example, see FIG. 18).

  The thinning length determination unit 25 determines the axial length of the defect at the circumferential position where the defect signal detection unit 24 has detected the defect signal 104, that is, the thinning length. The thinning length determination unit 25, for example, a B-scope type second image obtained by axial scanning at the circumferential position where the defect signal 104 is detected (see, for example, the second image shown in FIG. 20). Is determined as the thinning length Ry.

  The thinning map creation unit 26 determines the size and shape of the defect 111 based on the thinning length of the defect determined by the thinning length determination unit 25, and the distance Mx in the circumferential direction X and the distance My in the axial direction Y. The thinning map image 110 (see FIG. 21) to be displayed with the two-dimensional coordinates is created. The thinning map image 110 is displayed on the display unit 7.

  The thinning area analysis and evaluation unit 27 analyzes and evaluates the area of the defect 111 (that is, the thinning area) on the thinning map image 110 created by the thinning map creation unit 26.

  Note that the analysis unit 6 does not need to be connected to the storage unit 5 when the probe 3 performs circumferential scanning and axial scanning. Therefore, the analysis unit 6 may be stored in a place away from the place where the metal pipe P is installed, and connected to only the storage unit 5 or its memory 21 as necessary.

  Next, a defect evaluation method for the metal pipe P using the defect evaluation apparatus 1 will be described with reference to the flowcharts of FIGS.

  First, as a pretreatment, any rust or deposits on the surface of the metal tube P are removed in advance. Next, as shown in FIG. 5, the contact medium J is applied to a position where the probe 3 contacts on the surface of the metal pipe P exposed to the outside of the soil G. At this time, care is taken to make the contact medium J as thin and uniform as possible.

  After the pre-processing, circumferential measurement (step S1 in FIG. 16) is performed in which the probe 3 is moved in the circumferential direction X of the metal tube P and measurement is performed.

  Here, before performing the circumferential measurement, first, the probe 3 is attached to the circumferential guide 11. The procedure is as follows. First, the screw 13 is fixed in advance to the upper surfaces of the transmitting probe 8 and the receiving probe 9 of the probe 3, and the screw 13 is inserted into the spring 16 and the upper plate of the fixing jig 17. It inserts in the through-hole of 17c. Thus, the spring 16 is sandwiched between the upper plate 17c and the transmission probe 8 (or the reception probe 9).

  Thereafter, the nut 14 is screwed onto the screw 13 from above to bring the nut 14 into contact with the upper plate 17c. At this time, since the upper plate 17c is fixed so as not to move up and down with respect to the support column 17b, the lowering of the nut 14 is restricted by the upper plate 17c. Further, when the nut 14 is rotated to the right and pressed against the upper plate 17c, the probe 3 (specifically, the transmitting probe 8 and the receiving probe 9) rises together with the screw 13. The spring 16 is compressed between the upper plate 17c fixed to the column 17b and the transmission probe 8 (or the reception probe 9). As a result, the compressed spring 16 presses the transmitting probe 8 (or the receiving probe 9) downward.

  At this time, the height of the probe 3 is adjusted so that the bottom surface of the probe 3 (that is, the contact surface with the metal tube P) is positioned above the wheel 18. In this state, as shown in FIG. 5, the probe 3 and the circumferential guide 11 are arranged on the outer peripheral surface of the metal tube P. At that time, when the magnet 19 is attracted to the metal tube P, the circumferential guide portion 11 is in close contact with the surface exposed to the outside of the metal tube P.

  Thereafter, when the nut 14 is rotated counterclockwise, the probe 3 is lowered by pressing the probe 3 downward with a force to which the spring 16 is extended, and the probe 3 is moved to the metal tube P. Contact the outer peripheral surface. At this time, a load is applied in a direction in which the spring 3 is pressed against the outer peripheral surface of the metal tube P against the probe 3. When the probe 3 is pressed against the outer peripheral surface of the metal tube P by the urging force of the spring 16 as described above, the ultrasonic wave 101 that is a surface SH wave is applied from the probe 3 to the portion B where the metal tube P is embedded. It is possible to transmit and receive the reflected wave from the embedded portion B by the probe 3.

  In such a state, the probe 3 is moved in the circumferential direction X of the metal tube P to start circumferential scanning. Specifically, the operator manually moves the probe 3 and the circumferential guide portion 11 in the circumferential direction X while guiding the probe 3 in the circumferential direction X of the metal tube P by the circumferential guide portion 11. . As a result, the probe 3 is moved at a constant speed in the circumferential direction X of the metal tube P in a state where the probe 3 is in contact with a portion of the metal tube P exposed to the outside. At the same time, ultrasonic waves 101 that are surface SH waves are transmitted from the probe 3 to the embedded portion B, and the reflected wave 103 from the embedded portion B is received by the probe 3. The received signal regarding the reflected wave 103 is stored in the memory 21 of the storage unit 5.

  The amount of movement of the probe 3 and the circumferential guide 11 is detected by the rotary encoder 20. The circumferential measurement is continued until the circumferential set distance (for example, the entire circumference of the metal tube P) is completed while moving the probe 3 in the circumferential direction (steps S2 to S3).

  After the end of the circumferential direction measurement, the display unit 7 generates an image in the B scope format based on the signal related to the reflected wave 103 received by the probe 3, and displays the image. Specifically, the display unit 7 uses the B-scope-type first image shown in FIGS. 9B, 11B, and 13B from the data related to the signal obtained by the circumferential scanning. Is generated and displayed (first image display step). Then, the operator looks at the first image in the B-scope format and determines whether or not there is a defect signal related to the defect for each position in the circumferential direction X with respect to the signal data detected in the circumferential direction measurement (step). S4). If no defect signal is detected at that position in the circumferential direction X, the observation point is moved to another position in the circumferential direction until the set distance in the circumferential direction is completed, and the presence / absence of the defect signal is similarly determined (step) S5 to S6).

  On the other hand, when there is the defect signal S, the operator further determines whether the defect signal is a single signal by looking at the first image in the B-scope format (step S7). When the worker detects a plurality of defect signals at one position in the circumferential direction X, it is determined that the signal is not a single signal. In that case, the worker starts the axial measurement in which measurement is performed by moving the probe 3 in the axial direction Y of the metal tube P at the position in the circumferential direction X where a plurality of defect signals are detected (step S8). ).

  In the axial direction measurement, axial scanning is performed while the probe 3 is guided in the axial direction Y by the axial guide unit 12. Specifically, at the position in the circumferential direction X where a plurality of defect signals are detected, the operator guides the probe 3 while guiding the probe 3 in the axial direction Y of the metal tube P by the axial guide 12. And the circumferential direction guide part 11 is manually moved to the axial direction Y (specifically upward). As a result, the probe 3 moves the probe 3 in the axial direction Y of the metal tube P while guiding the probe 3 with the axial guide portion 12, and embeds the ultrasonic waves 101 that are surface SH waves from the probe 3. An axial scan is performed in which the probe 3 transmits the reflected wave 103 from the embedded portion B and receives the reflected wave 103 from the embedded portion B. A signal related to the reflected wave 103 received during the axial scanning is stored in the memory 21 of the storage unit 5.

  After the measurement in the axial direction, the observation point is moved to another position in the circumferential direction until the set distance in the circumferential direction is completed, and the presence / absence of a defect signal is similarly determined (steps S5 to S6).

  In this way, axial measurement is performed for all positions in the circumferential direction X where a plurality of defect signals are detected.

  When the worker detects a plurality of defect signals, the worker marks the surface of the metal pipe P with a marking or the like at a position in the circumferential direction X where the plurality of defect signals are detected, An axial measurement may be performed for each of the positions.

  After measuring in the circumferential direction as described above, the display unit 7 uses the B scope format shown in FIGS. 9B, 11B, and 13B from the data related to the signal obtained by the circumferential scanning. By generating and displaying the first image (first image display step), the operator evaluates the defect based on the first image in the B scope format. For example, FIG. 9B shows an upper end 51 of the crack at the position in the circumferential direction (X-axis direction) and the position in the axial direction (Y-axis direction) corresponding to the cracks C1 to C4 (see FIG. 9a). Since the two waveforms 53 and 54 corresponding to the lower end 52 are displayed, the operator can specify the positions and sizes of the defects C1 to C4 made of cracks.

  In the first image display step, it is preferable to perform aperture synthesis processing on a plurality of signals related to reflected waves received at a plurality of positions in the circumferential direction X in the circumferential scanning to generate a first image. This aperture synthesis improves the accuracy of specifying the position and size of the defect.

  Further, after the axial direction measurement is completed, the display unit 7 generates an image in the B scope format based on the signal related to the reflected wave 103 received by the probe 3, and displays the image. Specifically, the display unit 7 generates and displays the second image in the B scope format shown in FIG. 15 from the data related to the signal obtained by the axial scanning (second image display step).

  Thereby, the operator evaluates the defect based on the first image and the second image in the B scope format. For example, in the first image 58 in the B scope format shown in FIG. 13B, not only the positions corresponding to the upper end 56 and the lower end 57 of the defect C9 made of the corroded portion in FIG. It is displayed and the position and shape of the defect C9 consisting of the corroded part cannot be specified. Therefore, if the operator looks at the second image shown in FIG. 15, the waveform 61 of the signal reflected at the upper end 56 and the lower end 57 of the corroded portion C9 out of the waveform 60 of the signal due to reflection from the defect C9 consisting of the corroded portion. , 62 are clearly displayed in a downward-sloping shape that increases in the ultrasonic wave propagation direction (Y-axis direction) toward the probe scanning direction (Y-axis direction), so that signals due to reflection from other parts are displayed. It can be easily distinguished from the waveform. Thereby, the operator can specify the position and shape of the defect C9 which consists of a corrosion part.

  Next, as shown in the flowchart of FIG. 17, the analysis unit 6 analyzes data of signals obtained by the circumferential direction measurement and the axial direction measurement.

  In the analysis unit 6, first, the defect signal detection unit 24 determines whether or not there is a defect signal for each position in the circumferential direction X (step S11). For example, in the first image in the B scope format based on the signal obtained by the circumferential scanning shown in FIG. 18, the waveform 104 of the defect signal is displayed. Therefore, the observation cursor 105 is moved in the direction of the scanning distance Dx in the circumferential direction, and it is determined whether or not there is a defect signal for each position in the circumferential direction X (step S11).

When there is a defect signal, the analysis unit 6 determines whether or not the signal level is equal to or higher than a threshold value for the position in the circumferential direction X where the defect signal is present (step S12). For example, when the waveform 106 shown in the A scope type image regarding the beam path length l and the beam intensity p of the ultrasonic beam shown in FIG. when the beam intensity is a predetermined threshold value P ₀ or more (P ₀ or less in the negative region), as is the defect having a size that needs to be analyzed, the processing of the analysis unit 6, the following steps S13~S14 Are performed sequentially.

  In step S <b> 13, the thinning length determining unit 25 determines the thinning length in the axial direction Y. The thinning length determination unit 25 detects the defect signal based on the second image in the B scope format obtained by the axial scanning shown in FIG. 20 as described above at the position in the circumferential direction X where the defect signal exists. Of the waveform 107, the widths of the waveforms 108 and 109 of the signals reflected at the upper and lower ends of the defect are determined as the thinning length Ry.

  In step S14, the thinning map creation unit 26 determines the size and shape of the defect 111 as shown in FIG. 21 based on the thinning length of the defect determined by the thinning length determination unit 25. A thinning map image 110 to be displayed with two-dimensional coordinates of a distance Mx in the circumferential direction X and a distance My in the axial direction Y is created. The display unit 7 displays the thinning map image 110.

  The thinning area analysis / evaluation unit 27 analyzes and evaluates the area (that is, the thinning area) of the defect 111 on the thinning map image 110 created by the thinning map creation unit 26 (for example, a predetermined size or more). If it has an area of, a defect is automatically evaluated). Thereby, the analysis part 6 can function as a defect evaluation part which evaluates a defect based on the image displayed by said display part 7. FIG.

  The operator uses the B-scope format first image (for example, see FIG. 18) obtained by the circumferential scanning, the B-scope format second image (for example, FIG. 20) obtained by the axial scanning, and the thinning. Defects can be comprehensively evaluated based on the map image (see FIG. 21).

  As described above, the defect evaluation method according to the present embodiment is a defect evaluation method for evaluating the defect C generated in the portion B embedded in the soil G in the metal pipe P, and the probe 3 is attached to the metal pipe P. The probe is moved in the circumferential direction X of the metal tube P in contact with the part exposed to the outside, and an ultrasonic wave as a surface SH wave is transmitted from the probe 3 to the embedded part B, and the embedded part A circumferential measurement step of receiving a reflected wave from B by the probe 3, that is, a circumferential scanning step, and a B scope type signal based on a signal related to the reflected wave received by the probe 3 in the circumferential scanning step. A first image display step of generating a first image and displaying the first image on the display unit 7. In the circumferential scanning step in this defect evaluation method, the probe 3 is moved in the circumferential direction X of the metal tube P, and an ultrasonic wave which is a surface SH wave from the probe 3 to the portion B where the metal tube P is embedded. 101 is transmitted. Then, the reflected wave 103 from the buried portion B is received by the probe 3. Next, in the first image display step, the first image in the B scope format is displayed based on the signal related to the reflected wave 103 received by the probe 3. In the first image in the B scope format, it is possible to accurately know the position in the circumferential direction X of the metal pipe P and the position in the axial direction Y of the metal pipe P with respect to the defect C. As a result, the metal pipe P is buried. It is possible to accurately grasp the position and shape of the defect C in the portion B. Here, the SH wave tends to spread in the direction orthogonal to the traveling direction of the ultrasonic beam, but the probe 3 is moved in the circumferential direction X of the metal tube P as described above to perform circumferential scanning. By displaying the first image in the B scope format based on the reflected wave 103 obtained by scanning, it is possible to easily identify the position of the defect C in the circumferential direction X of the metal tube P. .

  In addition, in the defect evaluation method of the present embodiment, when the probe 3 receives a plurality of reflected waves at one position in the circumferential direction X during the circumferential scanning step, the probe 3 is metalized at the position. The probe 3 is moved in the axial direction Y, and ultrasonic waves, which are surface SH waves, are transmitted from the probe 3 to the embedded portion B, and the reflected waves from the embedded portion B are received by the probe 3. A second image in the B scope format is generated based on a signal related to the reflected wave received by the probe 3 in the axial direction measuring step, that is, the axial direction scanning step and the axial direction scanning step, and the second image is displayed. A second image display step for displaying on the unit 7 is further included. When the probe 3 receives a single reflected wave at one position in the circumferential direction X, it can be easily determined that the defect is a local defect C such as a through hole. When received, it may not be known whether the defect C is a crack extending linearly or a corroded part spreading in a planar shape. Therefore, in such a case, the probe 3 is moved in the axial direction Y of the metal tube P, and the ultrasonic wave 101 which is a surface SH wave is transferred from the probe 3 to the portion B where the metal tube P is embedded. The probe 3 transmits and the reflected wave 103 from the embedded portion B is received by the probe 3. And based on the signal regarding the reflected wave 103 received with the probe 3, the 2nd image of a B scope format is displayed. As a result, the position in the circumferential direction X and the position in the axial direction Y of the metal tube P of the defect C can be accurately identified, and the position and shape of the defect C can be grasped more clearly.

  In addition, the defect evaluation method of the present embodiment is a B scope thinning map that displays the position and shape of the defect C based on the signal obtained by the circumferential scanning step and the signal obtained by the axial scanning step. It further includes a thinning map display step of creating the image 110 and displaying the thinning map image 110 on the display unit 7. According to such a feature, the thinning map image 110 in the B scope format is created based on the signal obtained by the circumferential scanning process and the signal obtained by the axial scanning process. By evaluating the defect C using the meat map image 110 together with the first image and the second image, it is possible to grasp the position and shape of the defect C more accurately. In particular, the actual size and shape of the defect C can be easily grasped visually by the thinning map image.

  In the defect evaluation method of the present embodiment, the probe 3 is continuously moved in the circumferential direction X at a constant speed in the circumferential scanning step. That is, when circumferential scanning is performed using surface SH waves, the received signal tends to become unstable if the flaw detector 3 is stopped halfway, so that the flaw detector is continuously moved at a constant speed. It is possible to stabilize the received signal and maintain an accurate grasp of the position and shape of the defect C.

  Here, in order to transmit the SH wave to the metal tube P to be inspected, it is necessary to increase the viscosity of the contact medium interposed between the probe 3 and the metal tube P, but if the viscosity increases There is a problem that it takes time to stabilize transmission and reception of the ultrasonic beam and a problem that the scanning performance of the probe 3 is deteriorated. However, these problems can be solved by moving the flaw detector continuously at a constant speed as described above.

  In the present embodiment, the probe 3 of the defect evaluation apparatus 1 receives the transmitting probe 8 that transmits the surface SH wave to the embedded portion B and the reflected wave from the embedded portion B. And a receiving probe 8. In this way, by using two probes for transmission and reception as the probe 3, an area that cannot be measured at a position close to the probe 3 (for example, a position of 50 to 100 mm), that is, a surface dead zone. Can be prevented from occurring.

  The probe 3 includes two probes for transmission and reception. However, the present invention is not limited to this, and transmission and reception of ultrasonic waves with one probe. You may receive.

  In the defect evaluation method of the present embodiment, in the first image display step, the first image is obtained by performing aperture synthesis processing on a plurality of signals related to the reflected waves received at a plurality of positions in the circumferential direction X in the circumferential scanning step. Is generated. In this way, by performing aperture synthesis processing on the signals related to the reflected wave 103 received at a plurality of positions in the circumferential direction X, the same signal as when the probe 3 having a large aperture width transmits and receives the ultrasonic wave 101 is obtained. Thus, the position and shape of the defect C can be grasped more accurately.

  The defect evaluation method of the present embodiment includes a defect evaluation step of evaluating the defect C based on the first image, the second image, and the thinning map image. As described above, by evaluating the defect using the first image, the second image, and the thinning map image, it is possible to grasp the position and shape of the defect very accurately and evaluate the defect very accurately. Is possible. In the defect evaluation step, it is only necessary to evaluate the defect based on at least the first image. In this case, it is possible to accurately grasp the position and shape of the defect and accurately evaluate the defect. .

  Moreover, the defect evaluation apparatus 1 of this embodiment can transmit the ultrasonic wave which is a surface SH wave, and is embedded by the ultrasonic wave transmitted while being in contact with the exposed part of the metal pipe P. A probe 3 that receives a reflected wave from B, a guide portion 4 that has a circumferential guide 11 that guides the probe 3 in the circumferential direction X of the metal tube P, and a reflection that the probe 3 receives. A display unit 7 is provided for generating an image in a B scope format based on a signal related to the wave and displaying the image. According to this configuration, the probe 3 is moved in the circumferential direction X while guiding the probe 3 in the circumferential direction X of the metal tube P by the circumferential guide portion 11, and the probe 3 is moved from the probe 3 to the metal tube P. The ultrasonic wave 101 which is a surface SH wave is transmitted to the portion B where the probe 3 is embedded, and the reflected wave 103 from the portion B where the probe 3 is embedded is received. Then, the display unit 7 displays an image in the B scope format in the circumferential direction X (the first image described above) based on the signal related to the reflected wave 103 received by the probe 3. Thus, the operator can accurately know the position in the circumferential direction X of the metal tube P and the position in the axial direction Y of the metal tube P with respect to the defect C. As a result, it is possible to accurately grasp the position and shape of the defect C in the portion B where the metal pipe P is embedded.

  In the defect evaluation apparatus 1 of the present embodiment, the guide unit 4 further includes an axial guide unit 12 that guides the probe 3 in the axial direction of the metal pipe P. In this configuration, the probe 3 is moved in the axial direction Y while the probe 3 is guided in the axial direction Y of the metal tube P by the axial guide portion 12, and the metal tube P is embedded from the probe 3. The ultrasonic wave 101 which is a surface SH wave is transmitted to the part B, and the reflected wave 103 from the part B in which the probe 3 is embedded is received. Then, the display unit 7 displays a B-scope format image (the above-described second image) in the axial direction Y based on the signal related to the reflected wave 103 received by the probe 3. As a result, the operator sees the B-scope-type image in the circumferential direction (the first image described above) and the B-scope-type image in the axial direction (the second image described above) to thereby detect the metal about the defect C. It becomes possible to know the position of the pipe P in the circumferential direction and the position of the metal pipe P in the axial direction more accurately. As a result, it is possible to more accurately grasp the position and shape of the defect C of the portion B where the metal pipe P is embedded.

  Further, in the defect evaluation apparatus 1 of the present embodiment, the analysis unit 6 determines the size and shape of the defect 111 based on the signal related to the reflected wave received by the probe 3 and the distance Mx in the circumferential direction X and the axis. A thinning map creating unit 26 for creating a thinning map image 110 (see FIG. 21) to be displayed with two-dimensional coordinates of the distance My in the direction Y is provided. The created thinning map image 110 is displayed on the display unit 7. Thus, the operator can more accurately determine the position in the circumferential direction X of the metal pipe P and the position in the axial direction Y of the metal pipe P with respect to the defect C by looking at the thinning map image 110 displayed on the display unit 7. It becomes possible to know. As a result, it is possible to more accurately grasp the position and shape of the defect C of the portion B where the metal pipe P is embedded.

  Further, the defect evaluation apparatus 1 according to the present embodiment analyzes and evaluates the area of the defect 111 on the thinning map image 110 created by the thinning map creation unit 26 (that is, the thinning area) and evaluates it. A portion 27 is provided. Thereby, the area of the defect 111 can be accurately evaluated.

  In the defect evaluation apparatus 1 of the present embodiment, the guide unit 4 is a movement amount detection unit that detects the movement amount of the probe 3, specifically, the movement amount in the circumferential direction and the movement amount in the axial direction. A rotary encoder 20 is included. Therefore, the rotary encoder 20 can detect the amount of movement of the probe 3 in the circumferential direction X and the amount of movement in the axial direction Y. Thereby, it is possible to grasp | ascertain the position and shape of the defect C of the part B with which the metal pipe P was embed | buried more correctly.

  In this embodiment, the rotary encoder 20 is used as the movement amount detecting means for the probe 3. However, the present invention is not limited to this, and other movement amount detection such as a wire encoder is used. Means may be used.

  In the defect evaluation method of the above embodiment, the probe 3 and the axial guide portion 12 are moved upward in the axial direction Y when performing the axial scanning, but the present invention is not limited to this. Instead, it may move downward.

  In the defect evaluation method of the above embodiment, the metal pipe P whose lower end portion is buried in the soil G is described as an example of inspection, but the present invention is not limited to this. For example, the end of a metal tube may be embedded in concrete as an inspection target.

  In the defect evaluation apparatus 1 according to the above-described embodiment, the circumferential guide portion 11 of the guide portion 4 on which the probe 3 (the transmission probe 8 and the reception probe 9) is mounted is manually moved in the circumferential direction of the metal pipe P. However, the present invention is not limited to this. The defect evaluation apparatus 1 may be provided with a mechanism for automatically moving the circumferential guide 11, for example, a guide drive mechanism 31 that automatically moves the circumferential guide 11 as shown in FIG. 22 in the circumferential direction. You may prepare. The guide drive mechanism 31 includes a motor 32 having a drive shaft 32a, a transmission gear 33 fixed to the drive shaft 32a, a circumferential guide 34 extending in an arc shape along the circumferential direction of the metal tube P, and a circumferential guide. And a wheel 35 rotatably attached to 34.

  The circumferential guide 34 includes a main body portion 34a and a pair of arm portions 34b and 34c that are rotatably coupled to both ends of the main body portion 34a. The tip portions of the pair of arm portions 34b and 34c are coupled to the base portion 17a of the fixing jig 17 of the circumferential guide portion 11 by pins 34d and 34e so as to be rotatable around the pins. Since a plurality of teeth that can mesh with the transmission gear 33 are formed on the outer circumferential surface of the circumferential guide 34, the circumferential guide 34 moves in the circumferential direction of the metal pipe P as the transmission gear 33 rotates. It is possible to make it. The circumferential guide 34 is guided in the circumferential direction X by the wheels 35.

  By using the guide drive mechanism 31 configured as described above, the circumferential guide portion 11 can be automatically moved in the circumferential direction of the metal pipe P.

  Further, in the defect evaluation apparatus 1 of the above-described embodiment, the storage unit 5 has only the memory 21, and the operator looks at the first image in the B-scope format in the circumferential direction displayed on the display unit 7. Although it is determined whether or not there are a plurality of signals at one position in the direction, the present invention is not limited to this. The storage unit 5 may be configured to include a signal detection unit 22 as shown in FIG. 23 so that it can be automatically determined whether or not there are a plurality of signals.

  Specifically, the storage unit 5 illustrated in FIG. 23 includes the memory 21, the signal detection unit 22, and the notification unit 23. The signal detection unit 22 checks whether there is a defect signal related to a defect when the probe 3 performs a circumferential scan while moving in the circumferential direction X, and has a plurality of defect signals detected at one circumferential position? Detect whether or not. The notification unit 23 notifies the worker when the signal detection unit 22 detects that the defect signal includes a plurality of signals. For example, the notification unit 23 notifies the operator by sound such as a buzzer, a lamp, or an image display unit. It is means for visually informing. An operator who is informed that a plurality of defect signals are detected by the notification unit 23 can perform an axial scanning operation at a circumferential position where the plurality of defect signals are detected. Instead of providing the notification unit 23, an image notifying that a plurality of defect signals have been detected may be displayed on the display unit 7.

DESCRIPTION OF SYMBOLS 1 Defect evaluation apparatus 3 Probe 4 Guide part 7 Display part 8 Transmission side probe 9 Reception side probe 20 Rotary encoder (movement amount detection part)
26 Thinning map creation part 27 Thinning area analysis evaluation part P Pipe

Claims (10)

A defect evaluation method for evaluating defects generated in a portion embedded in soil or concrete in a metal pipe,
The probe is moved in the circumferential direction of the metal tube in a state where the probe is in contact with the exposed portion of the metal tube, and ultrasonic waves, which are surface SH waves, are transmitted from the probe to the embedded portion. , A circumferential scanning step of receiving a reflected wave from the embedded portion with the probe;
A first image display step of generating a first image in a B scope format based on a signal relating to a reflected wave received by the probe in the circumferential scanning step, and displaying the first image on a display unit;
When the probe receives a plurality of reflected waves at one position in the circumferential direction during the circumferential scanning step, the probe is moved in the axial direction of the metal tube at the position, An axial scanning step of transmitting an ultrasonic wave, which is a surface SH wave, from the probe to the embedded portion, and receiving a reflected wave from the embedded portion by the probe;
A second image display step of generating a B-scope type second image based on a signal related to the reflected wave received by the probe in the axial scanning step, and displaying the second image on the display unit;
A defect evaluation method comprising: Based on the signal obtained by the circumferential scanning step and the signal obtained by the axial scanning step, a B-scope-type thinning map image that displays the position and shape of the defect is created, and the reduction Further including a thinning map display step of displaying a meat map image on the display unit,
The defect evaluation method according to claim 1 . In the circumferential scanning step, the probe is continuously moved at a constant speed in the circumferential direction.
The defect evaluation method according to claim 1 or 2 . The probe includes a transmission probe that transmits the surface SH wave to the embedded portion, and a reception probe that receives a reflected wave from the embedded portion.
The defect evaluation method according to any one of claims 1 to 3 . In the first image display step, according to claim 1-4 for generating a plurality of signals the first image by performing synthetic aperture processing on the on the received reflected waves at a plurality of positions in the circumferential direction in the circumferential direction scanning step The defect evaluation method according to any one of the above. The defect evaluation method according to any one of claims 1 to 5 , further comprising a defect evaluation step of evaluating the defect based on at least the first image. A defect evaluation apparatus for evaluating defects generated in a portion embedded in soil or concrete in a metal pipe,
A probe capable of transmitting an ultrasonic wave which is a surface SH wave, and receiving a reflected wave from the embedded portion by the ultrasonic wave transmitted in a state in contact with an externally exposed portion of the metal tube; ,
A guide portion having a circumferential guide portion for guiding the probe in the circumferential direction of the metal tube , and an axial guide portion for guiding the probe in the axial direction of the metal tube ;
A display unit for generating an image in a B scope format based on a signal related to a reflected wave received by the probe, and displaying the image;
A defect evaluation apparatus. A thinning map creating unit that creates a thinning map for displaying the defect in a two-dimensional coordinate of the circumferential distance and the axial distance based on a signal related to the reflected wave received by the probe. And
The display unit displays the thinning map;
The defect evaluation apparatus according to claim 7 . The defect evaluation apparatus according to claim 8 , further comprising a thinning area evaluation unit that evaluates an area of the defect displayed on the thinning map. The guide unit includes a movement amount detection unit that detects a movement amount of the probe.
The defect evaluation apparatus of any one of Claims 7-9 .