JPS6170459A - Method and apparatus for adjusting sensitivity of ultrasonic flow detector - Google Patents

Abstract

PURPOSE:To adjust sensitivity even if a pipe with small diameter and thin thickness is used by forming a probe so as to be moved and rotated on the side of a sensitivity adjusting pipe on which artificial flaws are formed on its inner and outer surface so that respective positions of the axial length direction are different each other. CONSTITUTION:The titled device is provided with the sensitivity adjusting pipe 1, the probe 2, the artificial flaws A, B, photoelectric switches 3, 4, ultrasonic flaw detector 5, an operation controller 7, a probe moving device 8, etc. The pipe 1 is spirally sent in water in the axial length direction and the artificial inside and outside flaws A, B are formed. The switches 3, 4 and the probe 2 are arranged on the carrying area of the pipe 1 and the detecting signal of the probe 2 is applied to the controller 7. On the other hand, the probe 2 generates ultrasonic waves and catches echoes from the inside flaw A, the outside flaw B and the surface of the pipe to send the catched echoes to the flaw detector 5. Gates for detecting echoes are set up in the detector 5 by the controller 7. The probe 2 is fitted to the device 8 and can be moved in the horizontal and vertical directions which are rectangular to the axis of the pipe 1 and also rotated around the Z axis. Thus, the sensitivity can be adjusted even if a thin pipe is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for adjusting the sensitivity of an ultrasonic flaw detection device prior to ultrasonic flaw detection of a pipe, particularly a small-diameter thin-walled pipe, underwater using a probe.

[Prior art]

Quality assurance of steel pipes is generally performed based on flaw inspection using an ultrasonic flaw detector using a water immersion method.

As shown in Fig. 13, the oblique angle method is generally applied to this flaw inspection, and when inspecting for flaws in the longitudinal direction of the ° axis, the ultrasonic probe 2 is placed under a cover that is conveyed underwater. It is arranged at a predetermined incident angle ψ in a direction perpendicular to the tube axis with respect to the surface of the steel pipe 1', which is the test material. When the ultrasonic waves emitted by the ultrasonic probe (hereinafter simply referred to as the probe) 2 are incident on the tube, the inside of the tube is emitted.

It propagates in the circumferential direction of the tube while changing direction on the outer surface,
If, for example, an internal flaw A exists in the propagation path, the ultrasonic wave is reflected by the flaw A, and the echo thereof is detected by the probe 2. In this way, the presence or absence of defects.

The size is inspected, but since the ultrasonic energy is attenuated according to the propagation distance, if the incident angle of the probe 2 is not set appropriately, for example, if the inner and outer sides are of the same size. Even if a flaw exists, the captured echo level will be different, and there is a risk of misjudgment that the size of the flaw is different. Setting the position and angle of the child 2 is important in order to detect internal and external flaws with the same sensitivity. For this reason, regarding the angle, as shown in Figure 14, the detected echo height is affected by the incident angle. This is detected in advance using a steel pipe for sensitivity adjustment formed with
The incident angle ψ is set so that the detected echo levels are the same. This makes it possible to inspect flaws with the same sensitivity regardless of the location of the flaw, and the size of the flaw can be detected with high accuracy.

However, when using this method, after setting the angle of incidence as shown in Figure 15, it is necessary to make the detected echo levels of the inner and outer bottoms the same (the amplification is adjusted, and the gate is set after this adjustment, so this setting may be incorrectly done. If the detected echo levels at the inner and outer bottoms are not the same, the angle of incidence must be set again. For this reason, the probe's It was necessary to set the position within a range of ±15 μm, and the sensitivity adjustment required 5 to 6 hours.

Therefore, in recent years, an ultrasonic flaw detection device that can automatically adjust sensitivity in a short time has been developed. This device is designed to adjust the sensitivity by fixing the probe at a predetermined angle in advance.
The sensitivity adjustment principle utilizes the time difference based on the difference in the location of the internal flaw and the external bottom. To explain this in detail, the first
As shown in Figure 6 (A) (S in the figure is a surface echo), there are internal flaws,
In the time period when each echo +D and OD of the outer surface group appear, respectively,
External turning gates a and b are set in advance [Fig. 6 (b)], and the echoes appearing inside each gate are detected as internal and external bottom echoes, respectively, and the OD echo has a higher ID due to attenuation.
Since the detection level is lower than that of the echo, the gain of the amplifier is changed between each point in time when the OD echo and 10 echoes are detected after detecting the surface echo S, as shown in Figure 16 (C). By adjusting this sensitivity characteristic, internal and external defects can be inspected with the same sensitivity as shown in FIG. 16(d).

[Problem that the invention seeks to solve]

However, when inspecting thin-walled steel pipes using a device that can automatically adjust the sensitivity, it is difficult to adjust the sensitivity if the wall thickness of the steel pipe used for sensitivity adjustment is extremely thin.

There is almost no time difference in the appearance of the detection echo of artificial flaws on the external surface,
For this reason, it is difficult to separate the rain detection echoes using the gate, making it impossible to adjust the sensitivity, and in the case of the method shown in FIG. 15, there is a problem in that it takes too much time to adjust the sensitivity, as described above.

[Means for solving problems]

The present invention has been made in order to solve this problem, and the positions of the respective shafts in the longitudinal direction are made different.

A probe is movable once on the side of a sensitivity adjustment tube that has an artificial flaw formed on its outer surface, and the probe captures echoes from the tube surface and performs a search based on the echo level. The probe is set at the origin, moved further from this point and temporarily set to a predetermined angle of incidence, and then the tube for sensitivity adjustment is conveyed in the axial direction of the probe, and the detection time is different for the inner and outer surfaces. By moving the probe under certain conditions around the pipe in order to capture the echo from the flaw and find the position where the echo level should be the same, the ultrasonic flaw detection system can be used even in the case of small-diameter and thin-walled pipes. It is an object of the present invention to provide a sensitivity adjustment method and device that allow sensitivity adjustment.

A method for adjusting the sensitivity of an ultrasonic flaw detection device according to the present invention is a method for adjusting the sensitivity of an ultrasonic flaw detection device prior to ultrasonic flaw detection of a pipe in water using a probe, in which the respective axial positions are made different. A sensitivity adjustment tube with artificial flaws formed on its inner and outer surfaces is placed in water, and the probe is moved on the side of the sensitivity adjustment tube in a direction perpendicular to the tube axis, and rotated around this direction of movement. , determine the sensitivity adjustment origin where the echo signal from the sensitivity adjustment sound surface is at the maximum level, then set the water distance equal to the water distance between the probe and the sensitivity adjustment sound surface at the sensitivity adjustment origin, and set the sensitivity adjustment tube In order to set the ultrasonic incident angle to a predetermined value, the probe is moved from the sensitivity adjustment origin to the sensitivity adjustment tube direction and the movement direction perpendicular thereto, or rotated around the movement direction, and the probe is Temporarily set the flaw detection position and angle, then transfer the sensitivity adjustment tube in the axial direction of the tube, and inject ultrasonic waves into the sensitivity adjustment tube at the temporarily set position and angle and surrounding positions and angles. It is characterized by separately detecting the echo levels from the artificial flaws on the inner and outer surfaces, and setting the correction to the position and angle where the difference in these echo levels is minimized.

〔Example〕

The present invention will be specifically explained below based on the drawings.

FIG. 1 is a block diagram showing the device of the present invention that automatically adjusts the sensitivity of the ultrasonic flaw detection device together with the ultrasonic flaw detection device, FIG. 2 is a front view of the probe moving device 8, and FIG. 3 is a side view thereof. ,
In the figure, 1 indicates a steel pipe for sensitivity adjustment.The steel pipe 1 has a set of two drum-shaped rolls 14 (only one of which is shown in the figure) whose axis is slightly tilted horizontally from its axis. When the rolls 14 are rotated while being placed horizontally on a conveying device equipped with a plurality of sets, the steel pipe 1 is spirally fed through the water in the axial direction (in the direction of the white arrow) because the skew angle is given in advance. An artificial inner surface flaw A is formed at a position L2 from the tip, and an artificial outer surface flaw B is formed at a position L3 from the inner surface flaw A.

A photoelectric switch 3.4 for detecting the conveying speed and a probe 2 are located at a distance Lo from the downstream side in the conveying area of the steel pipe (■).

L, are arranged separately, and the photoelectric switches 3 and 4 are connected to the steel pipe 1.
The passage of the tip is detected, and a detection signal is given to the arithmetic controller 7 via the interface 6 connected to these.

The probe 2 oscillates ultrasonic waves underwater and the inner surface 7iiEA.

It captures echoes from the outer bottom B and the tube surface,
The angle and position relative to the steel pipe 1 are adjusted.

A signal related to the echo captured by the probe 2 is given to the ultrasonic flaw detection device 5.

The ultrasonic flaw detection device 5 controls the oscillation timing of the probe 2,
It also amplifies the signal captured by probe 2.

It detects flaws by detecting waves, and a gate for echo detection can be set by an arithmetic controller 7.

The interface 6 is connected to the output terminal of the ultrasonic flaw detection device 5, and the captured signal is sent to the interface 6.
It is output to the arithmetic controller 7 via.

An input device 11 is connected to the arithmetic controller 7, which controls the separation capacity 1111tLo of the photoelectric switches 3 and 4.

Steel pipe 1 dimension for sensitivity tll adjustment, roll 14 of tU feeder
The radius etc. are input to the arithmetic controller 7, and the method of moving the probe 2 to two temporarily set positions based on the direction of the flaw to be detected and the angle of incidence of the probe 2 or water at the temporarily set positions are input. It is now possible to select the distance correction method.

The arithmetic controller 7 calculates the separation distance LQ and the photoelectric switches 3 and 4.
Steel pipe 1 based on the difference in the rise time of the ON signal from each
A signal related to the detection echo height output from the ultrasonic flaw detector 5 is sent to the interface 6.
is entered via and reads this.

The output terminal of the arithmetic controller 7 has a display 12. Printer 13
are connected, and the conveyance speed and echo height calculated by the arithmetic controller 7 are displayed and recorded thereon. Note that the display 12. The printer 13 is used to display and record the results of flaw detection on the steel pipe, which is the material to be inspected, after the sensitivity of the ultrasonic flaw detection device 5 has been adjusted.

The probe 2 is attached to a probe moving device 8, and the probe moving device 8 moves the probe in the X-axis direction, that is, the horizontal direction perpendicular to the axial center of the steel pipe 1, and in the Y-axis direction, that is, the axial center of the steel pipe 1. It can move in the vertical direction perpendicular to the , and can also rotate in the θ direction, that is, around the Z axis.

The probe moving device 8 is composed of a probe moving mechanism 10 to which the probe 2 is attached and capable of moving it in a predetermined direction, and a drive device 9 for driving this. For example, as shown in FIG. It is as shown in Figure 3.

That is, above the steel pipe 1, a sliding stage 100 having an inverted trapezoidal cross section is provided horizontally with its longitudinal direction perpendicular to the pipe axis, and a moving carriage 101 is slidably engaged above the sliding stage 100. It is placed. The moving cart 101 is powered by a stepping motor 9
X by a transmission 123 that moves forward and backward in the
is moved in the axial direction. A vertically long round bar 105 for supporting a probe is passed through the movable cart 101, and the probe 2 attached to a probe mounting member 103 provided at the lower end of the round bar 105 is moved. The carriage 101 moves in the X-axis direction. A box body 102 is fixedly mounted on the movable cart 101, and a support arm 104 in a fold-back shape is attached to the side of the box body 102.
The lower part of the is fixed. A Z-axis circumferential stamping motor 91 with an output shaft in the vertical direction is provided at the upper part of the support arm 104, and the feed screw 10 is rotationally driven by the Z-axis circumferential stamping motor 91.
A height adjustment mechanism 121 is attached to rotate the probe 6 to move the probe 2 in the X-axis direction, that is, to raise and lower the probe 2. The feed screw 106 is connected to a gear box 122 and a box 102, which will be described later, provided on the box 102. It is connected to the round bar 105 that passes through the movable cart 101, and its lower end is moved in the X-axis direction by the Z-axis circumferential stamping motor 91. The round bar 105 is rotatably attached to the rotation of the feed screw via a bearing provided in the gear box 122, and a key is provided on the outer periphery of the bar 105. This round bar 10
On the outside of 5, a key groove is cut by a predetermined length in the vertical direction, and an outer cylinder 107 that allows the key to be moved in the vertical direction is inserted. This outer cylinder 1LO7 is connected to a rotating stepping motor 92 via a beher gear in a gear box 122, and as the stepping motor 92 rotates, the outer cylinder 107. Therefore, the probe 2 is rotated around the Z axis (in the θ direction).

The drive device 9 is connected to the arithmetic controller 7 via the interface 6.
Stepping motor 9 based on the operation signal input from
1.92.93 rotate forward or reverse. Therefore, this normal rotation,
By reversing the rotation, the probe moving mechanism 10 moves or rotates the probe 2 by a predetermined amount in the X-axis direction, the X-axis direction, and the θ direction.
It is detected by a pulse generator (not shown) attached to 93, and the detection signal is given to the arithmetic controller 7.

Setting of the angle 1 position of the probe 2 with respect to the steel pipe 1 is automatically performed by controlling the probe moving device 8 according to a program input and set to the arithmetic controller 7 in advance. FIG. 4 is a flowchart showing the control order.

The setting of the angle 1 position of the probe 2 with respect to the steel pipe 1 will be explained below. Prior to the inspection of the steel pipe as the material to be inspected, as shown in Fig. 5, the same material as the material to be inspected.

A steel pipe 1 for sensitivity adjustment, which has an outer diameter and has the aforementioned artificial flaws A and B formed in advance, is transported so as to reach the inspection area of the probe 2, and the sensitivity of the probe 2 is adjusted for this. When the operator turns on the start button of the input device 11, the arithmetic controller 7 causes the operation of setting the five angular positions of the probe 2 to be performed continuously and automatically.

FIG. 6 is an explanatory diagram of setting the probe 2 to the sensitivity adjustment origin according to the dimensions of the steel pipe 1 for sensitivity adjustment.

When the start button is turned on, the arithmetic controller 7 first drives the stepping motor 91 to move the probe 2 to a home position that is approximately at the same height as the axis of the steel pipe 1 placed on the roll 14 of the conveying device. emit a signal. This fixed position is Z
The axial direction and the θ direction are defined.

When the probe 2 is placed at a predetermined position of the probe moving mechanism 10 corresponding to the home position or when a mint switch is activated, the probe 2 is stopped at the home position.

Next, the arithmetic controller 7 determines the radius of the roll 14 of the conveying device, the radius of the steel pipe 1 and the following (based on equation 11), which are input in advance, at a position higher than the axial center of the roll 14 by a height Ho, that is, the axial center of the steel pipe 1. Calculates the position where the height is the same, outputs a signal to the stepping motor 91 around the Z-axis based on the height relationship between the calculated value and the home position, and moves the probe 2 upward or downward in the Z-axis direction. and occupy the position at the height Ho.

However, R: Radius of the roll 14 r: Radius of the steel pipe 1 L: Distance between the axes of the roll 14 After the probe 2 is moved to the height Ho position, the arithmetic controller 7 controls the ultrasonic flaw detection device 5. When the ultrasonic flaw detector 5 starts up and outputs an oscillation signal T as shown in FIG.
starts to capture surface echoes s, s2, etc., and when the oscillation signal T from the ultrasonic flaw detector 5 is input to the arithmetic controller 7, the arithmetic controller 7 detects the surface echoes in the ultrasonic flaw detector 5. The gate is set in the narrowest possible range including Sl based on the time difference between T and S1. As a result, the ultrasonic flaw detection device 5
detects only the surface echo S1.

The height H8 is the height at which the probe 2 is at the same height level as the axis of the steel pipe 1, which is determined by calculation.When the surface echo gate is set, the arithmetic controller 7 In order to set the probe 2 to the angle 1 position where the surface echo level from the steel pipe 1 is maximum, the exploration is started as follows.6 First, the arithmetic controller 7 operates the stepping motor 91 to adjust the height. The probe 2 is moved in the vertical direction (Z-axis direction) with H8 as the center for exploration, and the height position H1 at which the surface echo peaks is determined as shown in Figure 8 (analog chart showing the exploration results). , the stepping motor 91 is operated to move the probe 2 to the height position H1, and the stepping motor 92 is then operated to rotate the probe 2 in the θ and −θ directions. An angle θ1 at which the surface echo peaks at this time is determined.

Thereafter, the same operation as before is repeated, for example, twice, for a total of three times. As a result, the calculation controller 7 calculates 3 as the peak position and angle.
H3 and θ3 of the first flaw detection result are stored as the sensitivity adjustment origin.

Once this sensitivity adjustment origin (H3, θ3) is determined, the arithmetic controller 7 searches the probe 2 at a temporary setting position at a preset incident angle α using the determined sensitivity adjustment origin (H3, θ3) as a reference. An operating signal is output to the stepping motors 91, 92, and 93 necessary to position the tentacle 2.

Regarding this temporary setting, the setting method differs depending on the direction of the flaw to be detected. If you select to detect flaws in the axial direction, the sensitivity adjustment origin, that is, the maximum surface echo level, as shown in Figure 9, When the water distance (distance from the probe to the steel pipe) is constant, Z
In the axial direction, the height H4 is calculated using the following formula (2), and the height
The probe 2 is moved in the axial direction by a distance x1 calculated by the following equation (3).

)(4=rsinα-(21x1=r-rcosα-(31) Through this movement, the probe 2 is temporarily set at an angle 1 position at a predetermined incident angle α with respect to the circumferential direction of the steel pipe 1.

On the other hand, when the input device 11 selects to detect flaws in the circumferential direction, as shown in FIG.
Further, the probe 2 is moved in the X-axis direction by a distance x2 calculated by the following equation (4).

X2 = (D+E) (1-cosα) = (4
) However, D: Water distance E: Distance between the tip of the probe and the transducer Through this movement, the probe 2 is temporarily set at an angle 1 position at a predetermined incident angle α with respect to the axial direction of the steel pipe l. .

Next, correction settings are made to the optimum flaw detection condition angle 2°.

This setting includes a method of correcting the angle of incidence and a method of correcting the water distance. For example, when the method of correcting the angle of incidence is selected, the calculation controller 7 performs calculation control as follows. First, in order to set the defective echo gate at the temporary setting position,
As shown in FIG. 5, when the steel pipe 1 is spirally fed and its tips pass through the photoelectric switches 3 and 4, the rise time difference between the detection signals of the photoelectric switches 3 and 4 and the input separation pressure! 1iItL, and the conveyance speed (■) is measured based on the following.

The arithmetic controller 7 then informs the ultrasonic flaw detector 5 of the time (Ll +L
2) Set the inner bottom circumference gate in the narrowest possible time range in which inner surface flaws can be detected, centering on /V, and
+l, 2 +L3 ) The outer surface bottom circumference gate is set in the narrowest possible time range in which the outer surface bottom can be detected, centering on /V. As a result, the ultrasonic flaw detection device 5 detects echoes from the artificial flaws on the inner and outer surfaces, respectively.

Note that during this gate setting, the gain of the amplifier or attenuator (built in the ultrasonic flaw detection device 5) is adjusted.

After the defect echo gate is set by performing the inspection at the temporarily set angle 1 position in this way, the arithmetic controller 7 moves the probe 2 into the water at the temporarily set angle 1 position as shown in FIG. X
The probe 2 is sequentially moved to a position having a height H5 shown in the following equation (5) in the axial direction and a distance x3 shown in the following equation (6) in the X-axis direction.

Hs ”r sin (cr+H, Δα) −(51
However, n--3, 2,-1, 0, L, 2,3 3 points to the upper side (Δα, 2Δα, 3Δα), 3 points to the lower 11J (
−Δα, −2Δα, −3Δα).

Then, the steel pipe 1 is transported and explored at each of the two changing angle positions,
The arithmetic controller 7 calculates the difference in the echo levels from the detected inner and outer artificial flaws, selects the angle at which the difference is minimum, and operates the stepping motors 91 and 93 to position the probe at that angle. Let 2 be ruled. In other words, the correction setting is made to the optimum flaw detection condition position.

Note that the final setting of this optimum condition angle 1 position may be performed by a method of correcting the water distance. In that case, it is done as follows.

That is, as shown in FIG. 12, based on the output signal of the arithmetic controller 7, the probe moving device 8 moves the water distance of the probe 2 at a constant pitch Δβ around the temporarily set position while keeping the incident angle α constant.
For example, move 3 points in the direction where the water distance becomes shorter and move 3 points in the direction where it becomes longer, and move the probe 2. The ultrasonic flaw detection device 5 detects the internal pressure and external surface flaws of the steel pipe 1 being sent spirally at each change position, and the arithmetic controller 7 detects the minimum rain detection echo difference based on the detection results as in the previous method. Set the probe at one of the positions to achieve the angle.

Note that this final setting is not limited to either the method that corrects the incident angle or the method that corrects the water distance, but is the angle that minimizes the difference in detected echoes of artificial flaws on the inner and outer surfaces after performing both methods of exploration. The probe 2 may be set at one position.

Further, such correction setting to the optimum position is similarly performed in the case of the circumferential pressure shown in FIG. 10.

As described above, in the present invention, sensitivity can be adjusted even in the case of thin-walled tubes by differentiating the positions of the inner and outer flaws.

〔effect〕

As described in detail above, the present invention adjusts the sensitivity of an ultrasonic flaw detection device by temporarily setting the angle of incidence and then detecting the inner and outer bottoms formed apart in the axial direction of the tube for sensitivity adjustment. Since the sensitivity is adjusted by correcting the incident angle based on the metal tube,
In particular, sensitivity can be adjusted even for thin-walled tubes, and flaws can be detected with the same sensitivity regardless of their location.Furthermore, the present invention makes it possible to adjust sensitivity in about 30 minutes, significantly reducing time. The present invention has excellent effects, such as the ability to automatically adjust sensitivity when using the device of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the device of the present invention together with an ultrasonic flaw detection device, FIGS. 2 and 3 are front and side views of the probe moving device, and FIG. 4 is a flowchart showing the order of sensitivity adjustment of the present invention. , Fig. 5 is an explanatory diagram of gate setting, Fig. 6 is an explanatory diagram of probe origin setting, and Fig. 7 is a surface detected by setting the position of the probe in the Z-axis direction with respect to the steel tube for sensitivity adjustment. An explanatory diagram of echo and gate settings, Fig. 8 is an explanatory diagram of the probe sensitivity adjustment origin setting, Figs. 9 and 10 are explanatory diagrams of the temporary probe settings, and Figs. 11 and 12 are the optimum settings. FIG. 13, FIG. 14, and FIG. 16 are explanatory diagrams of the setting of the flaw detection condition angle 1, FIG. 16 are explanatory diagrams of conventional sensitivity adjustment, and FIG. 15 is a flowchart of the conventional sensitivity adjustment method. 1...Steel tube for sensitivity adjustment 2...Probe 3.4...
・Photoelectric switch 5... Ultrasonic flaw detection device 7... Arithmetic controller 8... Probe moving device patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Norio Kono Figure 2 Figure 3 Figure G H+ θ+ Ff2
θ2 Gate 3 θ3 8th Gate

Claims (1)

[Claims] 1. In a method for adjusting the sensitivity of an ultrasonic flaw detection device prior to ultrasonic flaw detection of a pipe underwater with a probe, the positions in the longitudinal direction of the respective shafts are made different, and the inner and outer surfaces are artificially Place the sensitivity adjustment tube with the flaw in the water, move the probe on the side of the sensitivity adjustment tube in a direction perpendicular to the tube axis, and rotate it around this direction of movement to emit the sensitivity adjustment sound. Determine the sensitivity adjustment origin where the echo signal from the surface reaches its maximum level, then set the water distance equal to the water distance between the probe and the sensitivity adjustment tube surface at the sensitivity adjustment origin, and set the ultrasonic incident angle to the sensitivity adjustment tube. In order to set the flaw detection position and angle to a predetermined value, the probe is moved from the sensitivity adjustment origin in the direction of the sensitivity adjustment tube and in the movement direction perpendicular thereto, or rotated around the movement direction, and the flaw detection position and angle of the probe are adjusted. Temporarily set, then move the sensitivity adjustment tube in the axial direction of the tube, and apply ultrasonic waves to the sensitivity adjustment tube at the temporary setting position, angle, and surrounding position angles to eliminate artificial flaws on the inner and outer surfaces. A sensitivity adjustment method characterized by separately detecting the echo levels of and setting the correction at a position and angle where the difference in these echo levels is minimized. 2. The sensitivity adjustment tube, which has artificial flaws formed on its inner and outer surfaces at different axial positions, is moved underwater in the axial direction, and during this time the probe emits ultrasonic waves. In a device that detects echoes from artificial flaws by entering the sensitivity adjustment tube and adjusts the sensitivity of the ultrasonic flaw detection device based on the detection results, the probe is placed in the axial direction of the sensitivity adjustment tube and A probe moving device installed to move in a direction perpendicular to the tube axis and rotate around a direction perpendicular to the tube axis, and a probe moving device based on echo signals captured by the probe. The device controls the moving position and rotational angle position of the probe, and is based on the echo signal from the sensitivity adjustment tube surface in the direction perpendicular to the tube axis of the probe where the echo signal reaches the maximum level. Determine the position and rotation angle position around this direction, and move from this determined position in the longitudinal direction of the tube axis and in the direction perpendicular to the tube axis in order to set the incident angle to a predetermined value while maintaining the water distance, or The echo levels from the artificial flaws on the inner and outer surfaces of the sensitivity adjustment tube, which is rotated around the moving direction and further conveyed in the axial direction of the tube, are detected separately, and a search is made to minimize the difference in these echo levels. A sensitivity adjustment device comprising: an arithmetic controller that corrects the position and rotational angle position of a feeler.