JP4559931B2 - Ultrasonic flaw detection method - Google Patents

Description

  The present invention relates to a nondestructive inspection method by ultrasonic flaw detection, and more particularly to an ultrasonic flaw detection method suitable for evaluation by ultrasonic flaw detection of a welded portion of a pipe member.

  Conventionally, ultrasonic flaw detection techniques have been widely used as a non-destructive inspection method for solids that allow the propagation of both longitudinal and transverse ultrasonic waves, such as steel. In the ultrasonic flaw detection test for confirmation (see, for example, Non-Patent Document 1), flaw detection with a probe that generates ultrasonic waves having a refraction angle of 45 ° is normally performed as a standard (for example, non-patent literature 1). (See Patent Document 2).

If a reflected wave (echo) that is suspected of being a defect is detected, a probe with a refraction angle of 60 ° of a transverse wave or a probe that generates a secondary creeping wave is applied. The presence or absence of a defect is confirmed (for example, refer nonpatent literature 3).
On May 1, 2001, text published by Japan Nondestructive Inspection Association, “Sound Flaw Test IV”, Chapter 6, Section 6.4 Japan Electric Association “Guidelines for Ultrasonic Flaw Testing in Inspections during Common Use of Light Water Nuclear Power Station Equipment” JEAG 4207-2004, Chapter 3, 3240 Japan Electric Association “Guidelines for Ultrasonic Flaw Tests during Inspection of Light Water Nuclear Power Station Equipment” JEAG 4207-2004, Chapter 4, 4250

  The above prior art does not give consideration to the presence of a weld back wave portion in the welded portion of the pipe member, and has a problem in the evaluation of reflected waves due to defects.

  In the conventional technology, as described above, when a suspicious reflected wave is detected during a standard flaw detection using a transverse wave having a refraction angle of 45 °, a flaw detection or secondary creeping wave is further generated by a probe having a refraction angle of 60 ° of the transverse wave. This is confirmed by conducting flaw detection with a probe.

  However, at this time, if there is a reflected wave from the weld back wave portion, it may be difficult to determine whether the wave is a reflected wave from a defect. This is mainly because, in the case of a pipe member, the shape of the weld back surface portion on the inner surface of the weld portion has a convex state.

  If the shape of the weld back wave portion is in a convex state, reflection of ultrasonic waves is likely to occur, so if there is a defect near the weld back wave portion, the reflected wave from the weld back wave portion will be reflected. This is because it cannot be ignored and cannot be distinguished from the reflected wave from the defect.

  An object of the present invention is to provide an ultrasonic flaw detection method in which a reflected wave caused by a defect can be displayed separately from a reflected wave caused by a weld back wave portion of a pipe member.

  The purpose of the ultrasonic flaw detection method is a method of ultrasonic flaw detection in which a welded portion of a tubular member is subjected to ultrasonic flaw detection to display reflected waves as an image, and the image is evaluated to determine the presence or absence of defects. A transverse ultrasonic wave and a longitudinal ultrasonic wave are propagated from the outer surface of the tubular member into the tubular member by the receiving ultrasonic probe, and depending on the position of the probe with respect to the welded portion of the tubular member The reflected wave captured by the flaw detection by the longitudinal wave is processed separately as the reflected wave captured by the flaw detection by the longitudinal wave, and the reflected image captured by the flaw detection by the longitudinal wave is displayed. As for the wave, the image is displayed after processing the reflected wave captured by the flaw detection by the longitudinal wave and then present in the weld and the image by the reflected wave from the defect existing in the weld. Separation of the image is achieved as given by the reflected wave by the shape of Se'uraha portion.

  At this time, the intensity of the reflected wave by the longitudinal wave, the intensity of the reflected wave by the ultrasonic wave that has been mode-converted from the transverse wave to the longitudinal wave, and then the mode conversion from the transverse wave to the longitudinal wave, and the longitudinal wave as it is The above object can also be achieved by adding a process for dividing and displaying the degree of the defect from the intensity of the three kinds of reflected waves of the reflected wave intensity by the ultrasonic wave.

  Furthermore, at this time, the ultrasonic probe includes an acoustic wedge, and the objective is achieved even if longitudinal waves and transverse waves can be transmitted and received simultaneously by the acoustic wedge, and the refraction angle of the longitudinal waves is 60 °. Even if it becomes, the said objective is achieved.

  According to the present invention, since the reflected wave from the defect can be displayed separately from the reflected wave from the welding back wave portion, the presence / absence determination of the defect with high reliability can be obtained.

  Further, according to the present invention, since the degree of the defect can be roughly grasped, it contributes to the improvement of the reliability of the defect sizing test performed in the next process.

  Hereinafter, an ultrasonic flaw detection method according to the present invention will be described in detail with reference to embodiments shown in the drawings.

  First, an automatic ultrasonic flaw detector used in the implementation of the present invention will be described with reference to FIG. 1. This is an automatic ultrasonic flaw detector used in an embodiment of the present invention when applied to a butt weld of a pipe member. An example is shown. In this example, the case where the pipe to be inspected (inspected pipe) is an austenitic stainless steel pipe is shown.

  At this time, a longitudinal wave having a refraction angle of 40 ° to 60 ° is transmitted and received, and a longitudinal wave and a transverse wave are simultaneously transmitted and received using an arbitrary refraction angle of 40 ° to 60 °. The ultrasonic probe 1 (hereinafter, simply referred to as a probe) that can be used is used to detect flaws in the welded portion of the pipe 2 to be inspected having the pipe outer surface 2a and the pipe inner surface 2b. It has become.

  Here, in the apparatus shown in FIG. 1, the refraction angle of the longitudinal wave of the ultrasonic wave by the probe 1 is set to 60 °, and the probe 1 is placed along the outer surface 2a of the pipe 2 to be inspected along the X axis. It is mounted on the scanner 3 that can be moved in the Y-axis direction and further moved in the Z-axis direction for pressing the probe, thereby automatically scanning the surface of the pipe 2 to be inspected with ultrasonic signals. The position signal is automatically recorded and the image can be displayed.

  More specifically, in FIG. 1, the probe 1 is first adapted to a longitudinal wave having a refraction angle of 60 °, and is held by the scanner 3 for flaw detection scanning of the pipe outer surface 2a of the pipe 2 to be inspected. At this time, the probe 1 is attached to the scanner 3 via the probe holder 4 so that it can be easily attached and detached.

  The scanner 3 is held movably by a track 5 arranged around the pipe 2 to be inspected in the circumferential direction (X direction). This is because the probe 1 is scanned in the pipe axis direction (Y direction). The arm 6 and the slider 7 are provided, and the probe 1 is held by the slider 7 via the probe holder 4.

  The scanning by the probe 1 at this time is a so-called rectangular scanning 8 as shown in the automatic flaw detection scanning explanatory diagram in the upper right of FIG. 1, which moves the scanner 3 in the circumferential direction by the track 5. Scanning in the X-axis direction and scanning in the Y-axis direction by moving the slider 7 back and forth (left and right in the figure) along the arm 6, whereby the probe 1 is connected to the pipe to be inspected. It is possible to move to all the parts to be subjected to ultrasonic flaw detection such as the welded part 2.

  The control signal required at this time is supplied from the control / recording / processing device 11 to the scanner 3 via the control cable 9, whereby the probe 1 transmits ultrasonic pulses and the trajectory 5. The movement of the scanner 3 and the movement of the slider 7 by the arm 6 are controlled, and a rectangular scan 8 of the pipe outer surface 2a of the pipe 2 to be inspected by the probe 1 is given. At this time, the scanner 3 detects the position information of the probe 1 with the circumferential position as the X coordinate and the axial position as the Y coordinate, and outputs it.

  On the other hand, the ultrasonic flaw detection signal obtained from the probe 1 at this time is input to the scanner 3 through the signal cable 10a, and from here, the control / recording / processing device 11 through the signal cable 10b together with the position information described above. The control / recording / processing apparatus 11 includes reflected waves of ultrasonic waves based on data and image signals recorded in real time, and as plane development views (C scope) and plate thickness direction sectional views (B scope). The image is displayed on the monitor 12 that is being operated.

  At this time, a printer 14 is connected to the control / recording / processing device 11 so that the above-described data and images can be output as flaw detection recording (automatic UT result output diagram) 13.

  Next, the operation of the ultrasonic flaw detection method according to the present invention will be described with reference to the following embodiments. As already described, this embodiment uses the automatic ultrasonic flaw detector described in FIG. 1, and at this time, as the probe 1, an acoustic wedge 16 made of acrylic resin is provided on the vibrator 1a as shown in FIG. A combination is used that allows longitudinal ultrasonic waves with a refraction angle of 60 ° to enter the pipe 2 to be inspected, and this is held by the probe holder 4 of the scanner 3. ing.

  First, the track 5 is installed in the vicinity of the welded portion of the pipe 2 to be inspected so that the welded portion of the pipe 2 to be inspected enters the scanning range of the probe 1 by the scanner 3, and then the control, recording and processing are performed. When the scanner 3 is controlled by the apparatus 11 and the probe 1 is at the position indicated by the solid line in FIG. 2, the automatic ultrasonic flaw detection operation is started with this position as the start position of the automatic ultrasonic flaw detection operation.

  Then, longitudinal ultrasonic waves 15 are transmitted from the transducer 1a in the probe 1, and propagate through the acoustic wedge 16 to reach the incident point 17a on the pipe outer surface 2a. At this incident point 17a, two kinds of ultrasonic waves, that is, the transverse wave 18a and the longitudinal wave 19 are inspected due to the difference between the speed of sound (acoustic wave propagation speed) in the acoustic wedge 16 and the speed of sound in the pipe 2 to be inspected. Propagates into the pipe 2.

  The speed of sound in the acoustic wedge 16 at this time is 2730 m / s in the longitudinal wave L when the material of the wedge is acrylic resin, but the speed of sound in the pipe 2 to be inspected is austenitic. In the case of stainless steel, the longitudinal wave L is 5790 m / s, and the transverse wave S is 3100 m / s.

  Here, according to the well-known Snell's law, the transverse wave 18a propagates inward from the pipe outer surface 2a of the pipe 2 to be inspected with a refraction angle α21 represented by the following formula (1), with an incident angle of θ20. After reaching the surface 2b and mode-converting to the longitudinal wave 23, it strikes and reflects the defect 24, and the mode-converted transverse wave 18b returns to the probe 1 along the same path. Therefore, in this case, the flaw detection is performed in the SLS conversion mode.

Refraction angle α21 = sin ⁻¹ {(V _S / V _A ) × sin (incident angle θ20)} (1)
V _S : Sound velocity of shear wave S in stainless steel (3100 m / s)
V _A : Sound velocity of longitudinal wave L in acrylic resin (2730 m / s)

  Here, in the control / recording / processing device 11, the position information (represented by XY coordinates) of the probe 1 at this time and the beam path of the ultrasonic signal (ultrasonic waves are incident on the probe 1). This is the data obtained by taking the propagation time to return in mm and the echo height of the reflected wave (the intensity of the reflected wave received by the probe 1 in% of the peak value). Process based on.

  Thus, in the above case, that is, in the case of the operation in the SLS conversion mode in which the transverse wave 18a propagates from the incident point 17a with the refraction angle α21 and the transverse wave 18b returns along the same path, the incident point Longitudinal ultrasonic waves from 17a are incident at a refraction angle β22 = 60 ° and processed as reflected.

  As a result, in the plan development view (C scope) displayed on the monitor 12 of FIG. 1, the reflected wave 32a is image-displayed as a reflected wave from the defect 24 as shown in an enlarged view in FIG. In the cross-sectional view in the plate thickness direction (B scope), the reflected wave 32b is image-displayed as a reflected wave from the defect 24 as shown in FIG.

The beam path length W _S of the transverse wave 18a from the incident point 17a to the pipe inner surface 2b in the pipe plate thickness direction sectional view of FIG. 2 is treated as a longitudinal wave and converted into a distance propagated as a longitudinal wave. result, until the beam path length W _S is a value that is replaced with the distance calculated by W _S × longitudinal acoustic velocity / shear wave velocity, this distance is reached after mode conversion in the pipe inner surface 2b in the defect 24 This is because the value obtained by adding the distances of the longitudinal waves 23 is regarded as the distance to the reflection source.

  In other words, the reflection from the defect 24 in the SLS conversion mode is actually performed, but in this embodiment, this is all treated as the reflection from the defect 24 by the longitudinal wave L as described above. As shown in FIG. 4, the reflected wave due to the defect 24 can be separated from the reflected wave 34a (described in detail later) due to the shape of the weld back portion 25 and displayed as a reflected wave 32a. The reflected wave by 24 can be separated from the reflected wave 34b (which will also be described in detail later) due to the shape of the weld back wave portion 25 and displayed as a reflected wave 32b.

  Next, as indicated by an arrow in FIG. 2, the probe 1 is moved backward by the scanner 3 (FIG. 1) so that the transverse wave 26 is incident from the incident point 17b on the pipe outer surface 2a. Send ultrasonic waves from. Then, the transverse wave 26 propagates as shown in the figure and reaches the inner surface 2b of the pipe, where it is converted into a longitudinal wave 27, reaches the defect 24 and is reflected, and the longitudinal wave 28 after the mode conversion is probed. Return to Child 1. Therefore, in this case, the SLL conversion mode is set.

  Also at this time, in the control / recording / processing apparatus 11, since the longitudinal wave ultrasonic wave is incident from the incident point 17b at a refraction angle of 60 ° and is reflected, it is processed. 12, as shown in an enlarged view in FIG. 3, the reflected wave 33 a is image-displayed as a reflected wave from the defect 24, and a sectional view in the thickness direction (B In the scope), as shown in the enlarged view of FIG. 4, the reflected wave 33b is displayed as a reflected wave from the defect 24.

This is because the transverse wave 26 (beam path length W _S ) from the incident point 17b to the pipe inner surface 2b in the sectional view in the plate thickness direction of the pipe in FIG. 2 is treated as a longitudinal wave and replaced with a distance propagated by the longitudinal wave. Therefore, the distance is calculated as W _S × longitudinal sound velocity / transverse wave sound velocity, and the distance of the longitudinal wave 27 and the mode conversion until reaching the defect 24 by mode conversion at the pipe inner surface 2b are converted to this distance. A value obtained by adding the distance of the longitudinal wave 28 until the longitudinal wave reaches the defect 24, is reflected, and returns to the probe 1 and is divided by 2 (the beam path is the ultrasonic round trip time divided by 2) Is displayed as the distance to the reflection source.

  That is, since the reflection from the defect 24 in the S-L-L conversion mode is actually processed as reflection by the longitudinal wave L, the reflected wave from the defect 24 is welded as shown in FIG. It can be separated from a reflected wave 34a (described later) due to the shape of the back wave portion 25 and displayed as a reflected wave 33a. The reflected wave due to the defect 24 is also reflected by the shape of the weld back wave portion 25 as shown in FIG. The image can be displayed as a reflected wave 33b separated from (described later).

  Next, the probe 1 is further moved backward from the incident point 17b so that an ultrasonic wave is transmitted from the incident point 17c which is also on the pipe outer surface 2a. Then, this time, the longitudinal wave 29 incident from the incident point 17c reaches the welding back wave portion 25 directly, and as a result, the longitudinal wave 29 directly hits and reflects the welding back wave portion 25, and the reflected wave Returns to the probe 1 as a longitudinal wave 29a.

  At this time as well, the position information (X coordinate and Y coordinate) of the probe 1 and the beam path and echo height which are ultrasonic signals are taken into the control / recording / processing device 11 and processed. Is the reflection of the longitudinal wave with a refraction angle of 60 ° as it is, and in the plan development view (C scope), the reflected wave by the longitudinal wave 29a is, as shown in FIG. An image is displayed as a reflected wave 34a depending on the shape, and as shown in FIG. 4, the image is also displayed as the above-described reflected wave 34b in the cross-sectional view in the thickness direction (B scope).

  Further, when the probe 1 is moved backward from the incident point 17c so that the ultrasonic wave is transmitted from the incident point 17d on the outer surface 2a of the pipe, the incident longitudinal wave 30 is opened at the inner surface at the root of the defect 24. As a result, the longitudinal wave 30 is reflected to become the longitudinal wave 30a, which returns to the probe 1.

  At this time as well, the position information (X coordinate and Y coordinate) of the probe 1 and the beam path and echo height which are ultrasonic signals are taken into the control / recording / processing device 11 and processed. Since the reflection of the longitudinal wave is as it is at a refraction angle of 60 °, the reflected wave by the longitudinal wave 30a is caused by the opening on the inner surface of the defect 24 as shown in FIG. The image is displayed as a reflected wave 35a, and in the thickness direction cross-sectional view (B scope), as shown in FIG. 4, the image is also displayed as the reflected wave 35b.

  Therefore, according to this embodiment, since the reflected wave from the weld back wave portion shape and the reflected wave from the defect are separated and displayed as an image, the reliability in determining the presence or absence of the defect can be further improved.

Further, according to this embodiment, the reflected wave from the defect can be displayed as a plurality of images, so that the shape of the defect can be identified, and also in this respect, the reliability in determining the presence or absence of the defect is improved. Can contribute.
More specifically, in this embodiment, in order to obtain a plurality of reflected waves 32a, 32b, 33a, 33b, 35a, 35b, 36a, 36b, as shown in FIGS. 17a, 17b, 17d, and 17e are sequentially changed. As a result, the defect 24 can be displayed as a plurality of images viewed from different positions. In this case, even in the same defect 24, the viewing direction Changes, so that the shape can be identified.

  Here, when the height of the defect 24 is higher than a certain level, at the incident point 17e between the incident point 17a on the pipe outer surface 2a and the probe 1 moving backward to the incident point 17b. In some cases, the longitudinal wave 31 incident from the probe 1 directly reaches the tip 24a of the defect 24. In this case, the incident longitudinal wave 31 is reflected by the tip 24a of the defect 24. The longitudinal wave 31a follows the same path and returns to the probe 1.

  Also at this time, the position information (X coordinate and Y coordinate) of the probe 1 and the beam path length and echo height are taken into the control / recording / processing device 11 and processed. In this case as well, the longitudinal wave refraction angle is 60 °. Therefore, in the plane development view (C scope), the reflected wave by the longitudinal wave 31 is displayed as an image as a reflected wave 36a by the defect 24 as shown in FIG. Similarly, as shown in FIG. 4, an image is displayed as a reflected wave 36b.

  In this case, the image display of the reflected wave 36a is the same as the longitudinal wave 30a at the incident point 17d as shown in FIG. However, even in this case, in the cross-sectional view in the plate thickness direction (B scope), the image of the reflected wave 36a is reflected as shown in FIG. Since it is displayed separately from the image of the wave 35a, it can be identified. Therefore, even in this embodiment, there is no possibility that a problem will occur.

  Here, the height of the reflected echo (intensity of the reflected wave) by the direct wave 37 (longitudinal waves 31 and 31a in FIG. 2) and the SLS mode converted wave 38 (the transverse wave 18a, longitudinal wave 23, and transverse wave 18b in FIG. 2). ) And the reflected echo height due to the SLL mode converted wave 39 (the transverse wave 26 and the longitudinal waves 27 and 28 in FIG. 2) are related to the defect height (depth). FIG. 5 shows the test results carried out according to the above embodiment. Here, in the following, the plate thickness serving as a reference for the defect height is the actually measured plate thickness Tmm in this figure.

  According to FIG. 5, in the region 40 where the defect height is 12% or less of the plate thickness, the echo heights of the direct wave 37 and the SLL mode converted wave 39 are all SLS. In the region 41 where the defect height is 12% to 25% of the plate thickness, which is lower than the mode conversion wave 38, the echo height due to the SLL mode conversion wave 39 is S-L. The echo height due to the direct wave 37 is also about 2 dB to 4 dB lower than the SLS mode converted wave 38, while it is higher than the −S mode converted wave 38 by about 0 dB to 8 dB. You can see that it is an area.

  In the region 42 where the defect height is 25% to 50% of the plate thickness, the echo height of the SLL mode converted wave 39 is about 8 dB to 16 dB larger than the SLS mode converted wave 38. However, it can be seen that the difference in echo height between the direct wave 37 and the SLS mode converted wave 38 is a characteristic region that is almost equal to about 0 dB to 2 dB.

  Further, in the region 43 where the defect height reaches 50% or more of the plate thickness, the echo height of the SLL mode converted wave 39 is about 16 dB larger than the SLS mode converted wave 38, and is almost On the other hand, it can be seen that the direct wave 37 and the SLS mode converted wave 38 are characteristic regions in which the echo heights are substantially equal.

  Then, as is clear from the result of FIG. 5, according to the above embodiment, the correlation between the defect height and the echo height can be obtained, and this is used by the control / recording / processing device 11. If there is a defect, the echo height of the direct wave, SLS mode converted wave, or SLL mode converted wave is further evaluated, and the degree of the defect is classified and displayed on the monitor 12. In addition, the monitor 13 is configured to print out. And the division at this time shall be as the following 1-4.

1
When the defect 24 has a height less than 12% of the plate thickness, that is, when it is determined that the defect 24 is in the region 40 in FIG. 5, the defect 24 is classified as a “small defect”.

2
If the defect 24 has a height of 12% or more and less than 25% of the plate thickness, that is, if it is determined that the defect 24 is in the region 41 of FIG. 5, it is classified as “medium defect”.

3
When the height of the defect 24 falls within 25% or more and less than 50% of the plate thickness, that is, when it is determined that the defect 24 is in the region 42 in FIG.

4
When the defect 24 has reached a height of 50% or more of the plate thickness, that is, when it is determined that the defect 24 is in the region 43 in FIG.

  Therefore, according to this embodiment, even when it is determined that there is a defect, the height (depth) of the defect is roughly classified and displayed, so that, for example, defect sizing performed in the next process A guideline for sizing can be obtained during (detailed flaw detection for evaluating defect height), which can contribute to improvement in sizing accuracy and work efficiency.

1 is a block configuration diagram showing an example of an automatic ultrasonic inspection device to which an embodiment of an ultrasonic inspection method according to the present invention is applied. FIG. It is sectional drawing for demonstrating operation | movement of one Embodiment of the ultrasonic flaw detection method by this invention. It is an expanded view for demonstrating operation | movement of one Embodiment of the ultrasonic flaw detection method by this invention. It is sectional drawing for demonstrating operation | movement of one Embodiment of the ultrasonic flaw detection method by this invention. It is a characteristic view for demonstrating operation | movement of one Embodiment of the ultrasonic flaw detection method by this invention.

Explanation of symbols

1: Probe (ultrasonic probe)
1a: vibrator 2: pipe to be inspected 2a: pipe outer surface 2b: pipe inner surface 3: scanner (scanner)
4: Probe holder (probe holder)
5: Orbit (X axis)
6: Arm (Y axis)
7: Slider (Slider)
8: Rectangular scanning (scanning method of the probe)
9: Control cable 10a: Ultrasonic signal cable (between probe and scanner)
10b: Ultrasonic signal cable (between scanner and control / recording / processing equipment)
11: Control / Recording / Processing device 12: Monitor
13: Flaw detection record (automatic UT result output diagram)
14: Printer (printer)
15: Ultrasound (longitudinal wave)
16: Acoustic wedge (acrylic resin)
17a: Incident point (at the time of mode conversion wave SLS or secondary creeping wave flaw detection)
17b: Incident point (at the time of mode conversion wave SLL flaw detection)
17c: Incident point (when flaw detection of weld back wave part)
17d: Incident point (at the time of flaw detection on the inner surface of the defect)
17e: Incident point (when detecting the tip of a defect)
18a: Transverse wave (at the time of mode conversion wave SLS flaw detection)
18b: transverse wave (mode-converted wave SLS flaw detection reflection)
19: Longitudinal wave (at the time of mode conversion wave SLS flaw detection)
20: Incident angle θ (in acrylic resin)
21: Refraction angle α (stainless steel transverse wave refraction angle)
22: Refraction angle β (stainless steel longitudinal wave refraction angle)
23: Longitudinal wave (mode conversion wave SLS flaw detection mode conversion)
24: Defect (including surface opening inside the defect)
25: Welding back wave part 26: Transverse wave (when mode-converted wave SLL flaw detection is incident)
27: Longitudinal wave (mode conversion wave SLL flaw detection mode conversion)
28: Longitudinal wave (mode conversion wave SLL flaw detection reflection)
29: Longitudinal wave (at the time of welding back surface flaw detection)
29a: Longitudinal wave (at the time of reflection of welded back surface flaw detection)
30: Longitudinal wave (at the time of entrance of flaw inside the defect)
30a: Longitudinal wave (when flaw detection is reflected on the inner surface of the defect)
31: Longitudinal wave (at the time of incidence of flaw detection)
31a: Longitudinal wave (when defect tip reflection is reflected)
32a: Reflected wave displayed on image (reflected wave by mode converted wave SLS)
32b: Reflected wave displayed on image (reflected wave by mode converted wave SLS)
33a: Mode converted wave SLL (planar development image display)
33b: Reflected wave displayed on image (reflected wave by mode-converted wave SLL)
34a: Reflected wave 34b of image-displayed welding back wave portion: Reflected wave 35a of image-displayed welding back wave portion: Reflected wave 35b of image-displayed defect inner surface opening portion: Image-displayed defect inner surface opening Reflected wave 36a: Reflected wave 36b of defect tip displayed on image: Reflected wave 37 of defect tip displayed on image 37: Relationship between defect height and echo height of mode converted wave SLS 38: Direct wave (longitudinal wave ) 39: Relationship between defect height and echo height 39: Relationship between mode height SLL defect height and echo height 40: Defect height is less than 12% of plate thickness 41: Defect height is 12% of plate thickness Area 42 of less than 25%: Area of defect height of 25% or more and less than 50% of sheet thickness 43: Area of defect height of 50% or more of sheet thickness

Claims (4)

In the ultrasonic flaw detection method of the method of ultrasonically flawing the welded portion of the tubular member and displaying the reflected wave as an image, evaluating the image to determine the presence or absence of defects,
Propagating ultrasonic waves of longitudinal waves and longitudinal waves from the outer surface of the tubular member into the tubular member by an ultrasonic probe that transmits and receives longitudinal waves and transverse waves simultaneously,
Depending on the position of the probe with respect to the welded portion of the tubular member, a flaw detection by a transverse wave and a flaw detection by a longitudinal wave are properly used,
About the reflected wave captured by the flaw detection of the transverse wave, the image is displayed after being processed as the reflected wave captured by the flaw detection by the longitudinal wave,
About the reflected wave captured by flaw detection by the longitudinal wave, by displaying the image after processing the reflected wave captured by the flaw detection by the longitudinal wave,
An ultrasonic flaw detection method characterized in that separation of an image due to a reflected wave from a defect existing in the welded portion and an image due to a reflected wave due to the shape of a welded back wave portion existing in the welded portion is provided. The ultrasonic flaw detection method according to claim 1,
The intensity of the reflected wave due to the longitudinal wave, the intensity of the reflected wave due to the ultrasonic wave that has been mode-converted from the transverse wave to the longitudinal wave, and then the mode conversion from the transverse wave to the longitudinal wave, and then converted into the longitudinal wave as it is The ultrasonic flaw detection method characterized by adding the process which classify | categorizes and displays the grade of the said defect from the intensity | strength of three types of reflected waves of the intensity | strength of the reflected wave by the existing ultrasonic wave. The ultrasonic flaw detection method according to claim 1,
An ultrasonic flaw detection method characterized in that the ultrasonic probe includes an acoustic wedge, and the acoustic wedge is configured to simultaneously transmit and receive longitudinal waves and transverse waves. The ultrasonic flaw detection method according to claim 3,
An ultrasonic flaw detection method, wherein a refraction angle of the longitudinal wave is 60 °.

Images