JPH11281627A - Automatic detection device of pipe body crack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic detection device of the crack of a pipe body for detecting the presence or absence of the generation of the crack of a tube, specifying a generation part, and further detecting the size of the generated crack. SOLUTION: An automatic detection device of a pipe body crack detects a crack in a pipe body using ultrasonic waves in water being filled into the pipe body and is provided with a reflection mirror 29 with first and second reflection mirror surfaces 26 and 28 that discharge ultrasonic waves toward a pipe wall while rotating around a rotary axis 30 along the longitudinal direction of the pipe body and receive ultrasonic echoes, a rotary device 32 for rotating the reflection mirror 29 around a rotary axis, a probe 34 for transmitting ultrasonic waves in parallel with the rotary axis and receiving reflected ultrasonic echoes, and a detector 12 that can advance and retreat in the pipe body. The first reflection mirror surface 26 allows ultrasonic waves to enter a pipe wall vertically and the second reflection mirror surface 28 allows ultrasonic waves to enter the pipe wall at a specific incidence angle obliquely. The first and second reflection surfaces 26 and 28 are arranged so that they occupy an area that do not exceed 1/2 of the incidence surface of ultrasonic waves from the probe 34 and they do not mutually overlap for the incidence direction of the ultrasonic waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic tube crack detecting device, and more particularly, to a tube crack detecting device for reliably and easily detecting the presence or absence of a crack in a tube, specifying a crack occurrence portion, and further detecting the crack occurrence. The present invention relates to a tube crack automatic detection device capable of detecting the size of a broken crack, and more particularly to an optimal device for automatically detecting a tube crack of a heat exchanger.

[0002]

2. Description of the Related Art In a petroleum refining plant for producing various petroleum products by refining crude oil, a petrochemical plant for producing various chemical raw materials and chemicals from a feedstock such as petroleum, etc., a large number of heat transfer tubes functioning as heat transfer tubes. Heat exchangers with tubes in the form of tube bundles are used in various places. Under severe operating conditions, the tubes provided in the heat exchanger may be damaged due to various causes such as vibration, metal fatigue, stress corrosion, and excessive stress due to tube expansion when manufacturing the heat exchanger. Often occurs. In particular, damage such as cracks (hereinafter collectively referred to as cracks)
Is easily generated in the tube in the region near the contact portion with the tube sheet and the baffle plate. When a crack occurs, grows, and completely penetrates the tube wall of the tube, the fluid flowing in the tube flows out of the tube through the crack penetrating the tube wall and mixes with the fluid flowing outside the tube. Quality may be reduced. Conversely, fluid may enter the tube from outside the tube.

[0003] For this purpose, it is confirmed that cracks do not occur in the tubes of the heat exchanger at the time of periodic inspection for temporarily stopping the operation of the factory and simultaneously inspecting and maintaining the equipment and piping in the factory. Inspection is taking place. Inspection of cracks and other damages on plate-shaped members such as the body wall of the tower tank and the pipe wall of pipes is usually performed. That is, the presence or absence of damage is determined by ultrasonic testing, magnetic testing, eddy current testing. This method is performed by non-destructive inspection methods such as the penetration method and the penetrant inspection method.However, in the case of heat exchanger tubes, the tubes in the form of a bundle of tubes are cracked. Difficult to do. In particular, when the tube inside the tube bundle is to be inspected, it is practically hardly accessible. Therefore, even if an attempt is made to apply a conventional non-destructive inspection method such as an ultrasonic inspection method, a magnetic inspection method, a penetration inspection method or the like, the inspection apparatus cannot be brought close to the inspection object, and thus cannot be applied. Further, the eddy current flaw detection method cannot detect the crack because the defect volume of the crack is very small. Therefore, inspection of the heat exchanger is generally performed by a hydraulic test method or an airtight test method. In the hydraulic test method or the airtight test method, if the test medium leaks by applying pressure from water or a test medium such as nitrogen or air to the inside or outside of the tube, cracks or holes are generated, and the test medium If no gas leaks, this inspection method assumes that no cracks have occurred.

[0004]

However, in the inspection by the hydraulic test method or the airtight test method, it is difficult to specify the location of the crack, and although the crack does not penetrate the tube wall, it is difficult to identify the crack. When a crack has occurred in the part, there has been a problem that it cannot be detected. In addition, by improving the general ultrasonic inspection method, the longitudinal wave from the probe is made incident on the tube at a right angle, and the time difference between the reflected waves from the inner surface and the outer surface of the tube wall is measured, whereby the thickness of the tube wall is measured. There is a way to measure However, this method can measure the corrosion depth of the pipe wall, but cannot detect cracks. Further, a method has been proposed in which an electric drill sandwiching the ultrasonic longitudinal wave probe at the tip is manually rotated to detect flaws in the vicinity of the tube sheet, but the applicable range of the inspection is several tens of cm from the tube sheet. The range of the extent is the limit,
Not applicable to long tubes and not practical.

As described above, it is difficult to reliably detect cracks generated in a tube by the water pressure test method, the airtight test method, and the conventional nondestructive inspection method, and it has not been practically satisfactory. Therefore, an object of the present invention is to provide an automatic tube crack detecting device capable of reliably and easily detecting the presence or absence of a tube crack, specifying the location of the crack, and detecting the size of the crack that has occurred. That is.

[0006]

In order to achieve the above-mentioned object, an automatic tube crack detecting apparatus according to the present invention is provided with an ultrasonic wave transmitted through water filled in a pipe, and a pipe wall of the pipe. A first and second reflecting mirror surfaces having different inclinations with respect to a rotation axis extending along the longitudinal direction of the tube body, and the reflecting mirror surface rotating around the rotation axis. A mirror that radiates ultrasonic waves toward the tube wall through the, receives ultrasonic echoes from the tube wall, a rotating device that rotates the mirror around the rotation axis, and reflects longitudinal ultrasonic waves parallel to the rotation axis A probe that transmits toward the mirror and receives the ultrasonic echo reflected from the reflecting mirror, and a detector that can advance and retreat in the longitudinal direction of the tubular body, and an ultrasonic echo analyzing means. The first reflecting mirror surface is provided at an inclination angle of 45 ° with respect to the rotation axis, and is provided from a probe. The reflected ultrasonic wave is made to be incident on the tube wall perpendicularly, and the second reflecting mirror surface is provided at an inclination angle θ with respect to the rotation axis, and reflects the ultrasonic wave incident from the probe and reflects the ultrasonic wave on the tube wall. A predetermined incident angle Φ that exceeds the longitudinal wave critical angle obliquely to
To generate a shear wave ultrasonic wave in the tube wall, and the first reflecting mirror surface and the second reflecting mirror surface each have a reflecting mirror surface region such that they do not overlap each other in the ultrasonic wave incident direction. And are arranged at predetermined intervals along the rotation axis.

[0007] The first reflecting mirror surface is provided at an inclination angle of 45 ° with respect to the rotation axis so that the ultrasonic wave incident from the probe is perpendicularly incident on the tube wall. On the other hand, the second reflecting mirror surface is rotated by a rotational axis such that ultrasonic waves are incident on the tube wall at a predetermined incident angle Φ exceeding the longitudinal wave critical angle, and oblique transverse ultrasonic waves are generated in the tube wall. Are provided at an inclination angle of θ. The relationship between θ and Φ is θ = 45 + Φ / 2, and Φ can be obtained from the relationship with the refraction angle, which is the traveling direction of the shear wave, by Snell's law. Since the incident angle Φ is larger than the longitudinal wave critical angle, when the ultrasonic wave enters the tube wall at the incident angle Φ,
Shear waves occur in the tube wall. Note that the longitudinal wave critical angle refers to the minimum ultrasonic incident angle at which total reflection of longitudinal ultrasonic waves occurs. The incident angle Φ is a parameter depending on the material of a tube such as a tube, and is an incident angle of an ultrasonic wave that generates only a transverse wave on the tube wall of the tube. The predetermined distance between the first reflecting mirror surface and the second reflecting mirror surface means that the ultrasonic longitudinal wave reflected on the first reflecting mirror surface and the second reflecting mirror surface and incident on the tube wall is incident on the tube wall. At the intervals where the points are at the same position, the reflected ultrasonic waves are reflected from the first and second reflecting mirror surfaces, and the reflected ultrasonic waves are incident from the first and second reflecting mirror surfaces so that the incident ultrasonic longitudinal waves do not interfere with each other. This is the length obtained by adding the distance separating the points, and varies depending on the material and diameter of the tube. In the case of a normal tube of a heat exchanger, the interval S on the rotation axis between the first reflecting mirror surface and the second reflecting mirror surface is S = (tube inner diameter (mm) / 2) × tan Φ +
α is defined as 0 ≦ α ≦ 20 mm. Preferably,
Each of the first reflecting mirror surface and the second reflecting mirror surface has at least one of the ultrasonic wave incident surfaces with respect to the ultrasonic wave incident direction.
/ 4 or more non-overlapping reflective mirror areas. For example, when the reflecting mirror surface close to the probe is the first reflecting mirror surface, the first reflecting mirror surface has an area of 1/4 or more and 3/4 or less of the ultrasonic wave incident surface. The second reflecting mirror surface has non-overlapping reflecting mirror surface regions obtained by subtracting the area of the first reflecting mirror surface from the ultrasonic wave incident surface. The same applies when the arrangement of the first and second reflecting mirror surfaces is reversed.

The frequency of the ultrasonic wave used in the present invention is selected according to the diameter of the tube, the thickness of the tube wall, the material, and the like.
In many cases, ultrasonic waves in the range of MHz to 20 MHz are used. The present invention can be applied regardless of the material of the tube as long as the tube can be made of a material capable of transmitting ultrasonic waves, and can be applied regardless of the size of the tube as long as a probe can be inserted. Ideal for automatically detecting cracks in vessel tubes, for example, tubes made of carbon steel, low alloy steel, stainless steel, copper alloy with a diameter of 19 mm or 25.4 mm and a thickness of 2.11 mm or 2.77 mm. is there. With the above configuration, the present invention measures the wall thickness of the tube with the first reflecting mirror, and determines the presence / absence of the circumferential crack of the tube, the place of occurrence, and the size of the crack with the second reflecting mirror over the entire length of the tube. It can be detected reliably.

In a preferred embodiment of the present invention, the reflector rotation detecting means is provided at the tip of the detector and detects the head of the ultrasonic echo for each rotation of the reflector, and is linked to the reflector rotation detecting means. And an encoder for detecting the position of the detector in the longitudinal direction of the inside of the tube, and the position where the crack occurs is detected by cooperation between the reflector rotating means and the encoder. Detecting the position of the crack in the circumferential direction of the tube by the reflector rotation detection means,
The position of the crack in the longitudinal direction of the tube can be detected by the encoder.

[0010] In a further preferred embodiment of the present invention, the rotating device is an ultrasonic motor. Thus, the reflecting mirror can be rotated at a uniform angular velocity without rotating the rotation axis. Further, in a further preferred embodiment of the present invention, a flow path for feeding water for filling the ultrasonic propagation path in the tube with water, an electric wire for supplying power to the ultrasonic motor, a probe and a pulser A cable for transmitting and receiving signals to and from the receiver is connected to the detector, and the flow path, the electric wire, and the cable are pulled so that the detector travels in the tube.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment Example This embodiment is an example of an embodiment of an automatic tube crack detection device according to the present invention. FIG. 1 is a schematic diagram showing the entire configuration of the tube crack automatic detection device, and FIG. FIG. 3 is a detailed view of the detector inserted into the tube, and FIG. 3 is an arrangement diagram of first and second reflecting mirror surfaces along the incident direction of the ultrasonic wave. The automatic tube crack detection device (hereinafter simply referred to as a “detection device”) 10 of the present embodiment detects cracks generated in the tube wall of a tube by ultrasonic waves propagated in water filled in the tube. As shown in FIG. 1, a detector 12 capable of moving back and forth in a tube in a longitudinal direction, an encoder 14 for detecting a position of the detector 12 in the tube longitudinal direction, and transmitting and receiving an ultrasonic echo signal Pulsar receiver 16
A controller 18 for receiving an output signal from the pulsar receiver 16, a computer (recorder) 20 which is a small computer such as a personal computer and functions as a data recording device and a data analyzing device for data output from the controller 18; A synchroscope 22 provided as a display device.

As shown in FIG. 2, the detector 12 includes a detector housing 24 and first and second reflecting mirror surfaces 2 in a rotating cylinder 40.
6 and 28, and a reflecting mirror 29 provided outside the detector housing 24 and a reflecting mirror 29 provided inside the detector housing 24.
Has an ultrasonic motor 32 that rotates the imaginary rotation about a virtual rotation axis 30, and a probe 34 that transmits and receives ultrasonic waves, and is connected to the encoder 14 via a flexible cable 36. The front of the reflector 29 and the detector housing 24
A ring-shaped rotating shaft retainer / water damming ring 37 is provided at the front and rear portions. The rotating shaft holder / water blocking ring 37 is formed of a ring made of metal, plastic, or the like so that it can slide freely along the inner peripheral surface of the tube, and holds the rotating shaft 30 at the longitudinal center line of the tube. In addition, it also has a function of blocking the water supplied by the flow path in the cable 36.

The probe 34 is a vertical probe for immersion in water, and makes the first ultrasonic wave of the reflecting mirror 29 parallel to the rotation axis 30.
And the ultrasonic waves reflected from the first and second reflecting mirrors 26 and 28, and the ultrasonic echoes reflected from the first and second reflecting mirrors 26 and 28 are received.

The reflecting mirror 29 includes the first and second reflecting mirror surfaces 2.
6 and 28, and a rotating cylinder 40 that rotates integrally while holding the first and second reflecting mirror surfaces 26 and 28. The rotating cylinder 40 is connected to a rotor 38 that is driven by an ultrasonic motor 32 and rotates around the rotation axis 30. The first and second rotating cylinders 40 have a uniform angular velocity around the rotation axis 30 in accordance with the rotation of the rotor 38. It rotates integrally with the second reflecting mirror surfaces 26 and 28.

The first reflecting mirror surface 26 is provided at an inclination angle of 45 ° with respect to the rotation axis 30 as shown in FIG.
In addition, as shown in FIG. 3B, it occupies the right half of the incident surface of the ultrasonic wave from the probe 34. On the other hand, the second reflecting mirror surface 28 is provided at an inclination angle θ larger than 45 ° with respect to the rotation axis 30 as shown in FIG.
As shown in (b), it occupies the left half of the incident surface of the ultrasonic wave from the probe 34. Thereby, the first reflecting mirror surface 2
The sixth and second reflecting mirror surfaces 28 are arranged so as not to overlap with each other in the incident direction of the ultrasonic wave. Note that this is an example of the size and arrangement of the first reflecting mirror surface 26 and the second reflecting mirror surface 28, and for example, the first reflecting mirror surface 26
Is located on the right side with an area of 3/4 of the ultrasonic wave incident surface, and the second reflecting mirror surface 28 is located on the left side with a quarter of the ultrasonic wave incident surface that does not overlap each other. You may have it. Further, the second reflecting mirror surface 28 has a reflecting mirror surface which is １ ／ or more of the ultrasonic wave incident surface as long as it has a region of the reflecting mirror surface which is not overlapped with each other by １ ／ of the ultrasonic wave incident surface on the left side. May be. 45 ° tilt angle with respect to rotation axis 30
The first reflecting mirror surface 26 provided by the reflector reflects the ultrasonic wave incident from the probe 34, and the opening 42 of the rotary cylinder 40 (FIG. 2).
) Perpendicularly to the tube wall, and then receives an ultrasonic echo and reflects it toward the probe 34. Second reflecting mirror surface 28 provided at an inclination angle θ with respect to the rotation axis
Reflects the ultrasonic wave incident from the probe 34, passes through the opening 44 (see FIG. 2) of the rotary cylinder 40 and obliquely enters the tube wall at an incident angle Φ, and then receives an ultrasonic echo. And is reflected toward the probe 34.

In this embodiment, the inclination angle θ of the second reflecting mirror surface 28 is defined by an incident angle Φ at which an ultrasonic wave is incident on the tube wall so as to generate only a transverse wave having a refraction angle of 45 ° in the tube wall. Is done. Note that the refraction angle of 45 ° is one example, and is not necessarily 45 °. For example, it is assumed that the tube is made of carbon steel and generates a transverse wave having a refraction angle of 45 °. The velocity of longitudinal ultrasonic waves in water is 1480.
m / sec, speed in carbon steel is 5900 m / sec.
On the other hand, the velocity of the shear wave ultrasonic wave in the carbon steel is 3230 m / sec. Therefore, in order for a longitudinal ultrasonic wave incident on the tube wall at an incident angle Φ to become a transverse wave having a refraction angle of 45 ° in the tube wall, Sin Φ / 1480 = Sin 45 ° / 3230, and therefore Φ ≒ 18.8 ° is there. On the other hand, the incident angle α of the ultrasonic wave to the second reflecting mirror surface 28 is α = (180−90−Φ) / 2 = (90−Φ) / 2 Also, since α = 90−θ, θ = 90−α = 90− (90−Φ) / 2 = 45 + Φ / 2. Therefore, if Φ ≒ 18.8 °, θ = 54.
4 °.

As shown in FIG. 3, the incident point of the ultrasonic wave incident from the second reflecting mirror surface 28 is the same as the incident point of the ultrasonic wave incident from the first reflecting mirror surface 26 or 20 mm from that position. Within the first reflecting mirror surface 26
And the second reflecting mirror surface 28 are respectively inclined with respect to the rotation axis 30 and arranged at an interval S (see FIG. 3).
The interval S is S = (tube inner diameter (mm) / 2) × tan Φ +
α (α ≦ 20 mm).

As shown in FIG. 3, the cable 36 is connected to the head of the detector housing 24, and has a water flow path 46 inside, an electric wire 48 for supplying power to the ultrasonic motor 32, and the probe 3 inside.
And a signal line 50 for transmitting and receiving signals between the pulsar receiver 4 and the pulsar receiver 16. The water supplied from the water tank 54 through the flow path 44 by the submersible pump 56 is
7 to fill the tube and form an ultrasonic underwater propagation zone.

A rotation recognition bar 52 is attached to the tip of the detector housing 24, and the ultrasonic wave from the first reflecting mirror surface 26 is applied to the rotation recognition bar 5 every one rotation of the reflecting mirror 29.
2, the first and second reflecting mirror surfaces 2
It recognizes that 6, 28 has made one rotation. Rotation recognition bar 5
With the cooperation of the encoder 2 and the encoder 12, the position of the crack generated in the tube can be specified in the circumferential direction and the longitudinal direction of the tube.

The pulsar receiver 16 is connected to the transmission / reception signal line 5.
0 and is connected to the detector 12 to receive an ultrasonic echo from the probe 34. The controller 18 is connected to the encoder 14 via the position signal cable 58, receives the position signal of the detector 12 from the encoder 14, and
The ultrasonic signal obtained from the pulser receiver 16 is displayed on the synchroscope 22, and the ultrasonic signal is A / D converted and output to the computer (recorder) 20. The computer (recorder) 20 and the synchroscope 22
The computer (recorder) 20 is provided as an ultrasonic echo analysis unit and a real-time display unit.
Analyze the ultrasonic echo signal to detect the presence of cracks and their dimensions.

Hereinafter, a method for detecting a circumferential crack generated in a carbon steel tube using the detecting device 10 will be described with reference to FIGS. When the ultrasonic wave is transmitted from the detector 12 toward the tube via the first and second reflecting mirror surfaces 26 and 28, the velocity of the longitudinal wave in the carbon steel tube is 5900 m / sec, and the velocity of the shear wave is 3230 m. / Sec, this speed difference and the first and second reflecting mirror surfaces 2
From the intervals of 6 and 28, the reception order of the ultrasonic echo signals is displayed on the display screen of the pulser receiver 16 as an A scope as shown in FIG. In the A scope shown in FIG. 4, a vertical surface echo (S) from the tube surface (inner wall surface) incident on the probe 34 via the first reflecting mirror surface 26 sequentially along the time axis (horizontal axis). Wave), the first bottom echo (B1 wave) from the tube back surface (outer wall surface),
The second bottom echo (B2 wave), the third bottom echo (B3 wave),... If cracks have occurred in the tube, the probe 34
The defect echo (F wave) from the crack occurrence part incident on
Appears on A scope.

On the A scope obtained in this manner, the wall thickness of the tube is measured from the time difference between the vertical surface echo S wave and the first bottom surface echo B1 wave. , S wave and B1 wave, it is possible to measure the thinning of the tube outer surface. The presence / absence of a crack is confirmed from the presence / absence of the F-wave of the A scope, and the position of the crack in the tube longitudinal direction is confirmed from the encoder 14 interlocked with the detector 12. If no crack is generated in the tube, the transverse ultrasonic wave incident on the tube from the second reflecting mirror surface 28 is not reflected back, so that there is no defect echo on the A scope.

In this embodiment, as shown in FIG.
The vertical echoes (S, B1, B2,...) And the oblique echoes (F) of the scope are gated by the controller 18 and separately taken out. To display. For example, when the number of rotations of the reflecting mirror surfaces 26 and 28 is 1,000 rpm and the number of ultrasonic pulses, that is, the A-scope signal is 2,000,
The number of A scopes for one rotation of the reflecting mirror surfaces 26 and 28 is 2,
000 / (1,000 / 60) = 120.

FIG. 6 is a diagram in which the A scope data for one rotation of the vertical echo obtained through the first reflecting mirror surface 26, that is, the A scope data of 120 in the above example is developed, The length corresponding to the time corresponding to the detection of the surface wave S from the time axis is added in the horizontal direction in the drawing to obtain the S axis, and the length corresponding to the time of (B1-S) is added in the horizontal direction in the drawing. The sum is displayed as the B1 axis. In the example of FIG. 6, the corrosion state of the outer surface of the tube is shown on the B1 axis, and the corrosion state of the inner surface of the tube is shown on the S axis. In this example, corrosion occurs on the outer surface of the tube, and on the inner surface of the tube, No corrosion has occurred.

FIG. 7 is an expanded view of the oblique echo obtained through the second reflecting mirror surface 28 in the same manner as FIG. 6, and shows a case where the oblique echo is present. In the same manner as in the above example, it is possible to determine whether the inner surface of the tube is cracked or the outer surface of the tube is corroded, and detect the circumferential position and the length of the crack. Since the crack of the tube is almost always generated in the circumferential direction, the A-scope data during one rotation of the detector 12,
In the above example, the ratio of the continuous oblique echo detected during one rotation of the detector 12, that is, the defect echo (F), to the 120 A-scope data is determined by the circumferential crack length (FIG. 7).
Then, it is detected as F). By combining FIG. 6 and FIG. 7, it is also possible to simultaneously display external corrosion data and internal surface cracking data as shown in FIG.

In order to evaluate the detection apparatus 10 of this embodiment, the following tube defect detection test was performed. First, as shown in FIG. 9 (a), the entire inner surface of the inner wall is reduced in thickness to 2 mm and 1 mm, the inner surface slit-shaped crack is 1 mm in width and 1/4 circumference, the through hole is 3 mm in diameter, and the diameter is 2 mm × 2 mm in depth. Flat bottom hole, flat bottom hole of 1 mm diameter x 1 mm depth and 2 mm depth;
A test tube having a thickness reduction of 5 mm and 1 mm on the entire outer surface was prepared, and a detection test of a tube defect was performed using the detection device 10 of the present embodiment. FIG. 9A is a cross-sectional view of the test tube, in which the broken line indicates the inner wall surface of the tube and the solid line indicates the outer wall surface of the tube. FIG. 9B shows a computer (recorder) 20 that synthesizes and analyzes an ultrasonic echo obtained via the detector 12 and a longitudinal position of the detector 12 obtained from the encoder 14, and the computer (recorder) 20. FIG. 9 (c) shows a tube defect and a void in the longitudinal direction of the test tube on FIG. 20, and FIG. 9 (c) shows the longitudinal and circumferential positions of the defect.

In this embodiment, as can be seen from the results of the above-described detection test, the A-scope signal is converted into digital data by the controller 18 and analyzed by the computer (recorder) 20 to obtain information on the tube thickness and corrosion information. The position in the longitudinal direction of the crack in the tube and the length in the circumferential direction can be accurately displayed. The crack depth can be detected by computer analysis of the beam path of the defect echo and the change in the echo height according to the same method as the general oblique flaw detection method.

[0028]

According to the present invention, the first reflecting mirror surface for reflecting the ultrasonic wave incident from the probe and emitting the ultrasonic wave perpendicularly to the tube wall and the incident light exceeding the longitudinal wave critical angle on the tube wall, respectively. Angle Φ
By providing a reflecting mirror having a second reflecting mirror surface to be incident on the tube, emitting the ultrasonic wave toward the tube wall while rotating the reflecting mirror, and then receiving the ultrasonic echo, it is possible to reliably and easily form the tube. An automatic crack detection device for a pipe body capable of detecting the presence or absence of crack generation, specifying the location where the crack has occurred, and detecting the size of the generated crack is realized. The automatic tube crack detection device according to the present invention is optimal as a device for automatically detecting a tube crack in a heat exchanger.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the entire configuration of an automatic tube crack detection device.

FIG. 2 is a detailed view of the detector inserted into a tube.

FIG. 3 is an arrangement diagram of first and second reflecting mirrors along an incident direction of an ultrasonic wave.

FIG. 4 is a diagram showing an example of an A scope for vertical echo and oblique echo.

FIG. 5 is a diagram illustrating that a vertical echo and an oblique echo are separately processed.

FIG. 6 is a diagram of a vertical echo for one rotation of the first reflecting mirror.

FIG. 7 is a diagram of a vertical echo for one rotation of a second reflecting mirror.

FIG. 8 is a diagram of an echo obtained by combining FIGS. 6 and 7;

9 (a) is a view showing a defect in the test tube, FIG. 9 (b) is a view showing the tube defect and the void in the longitudinal direction of the test tube, and FIG. 9 (c) is the longitudinal direction of the defect. It shows the position in the direction and the circumferential direction.

[Explanation of symbols]

10 Embodiment of automatic tube crack detection device according to the present invention 12 Detector 14 Encoder 16 Pulser receiver 18 Controller 20 Computer (recorder) 22 Synchroscope 24 Detector housing 26 First reflecting mirror surface 28 Second Reflecting mirror surface 29 Reflecting mirror 30 Rotating shaft 32 Ultrasonic motor 34 Probe 36 Cable 37 Rotating shaft holder and water blocking ring 38 Rotor 40 Rotating cylinder 42, 44 Opening 46 Flow path 48 Electric wire 50 Signal line 52 Rotation recognition bar 54 Water tank 56 Submersible pump 58 Position signal cable

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Eiichi Kishi 9138 Goi, Ichihara, Chiba Pref.

Claims (5)

[Claims] An apparatus for detecting cracks generated in a pipe wall of a pipe by ultrasonic waves propagated in water filled in the pipe, wherein the apparatus detects a crack on a rotation axis extending along a longitudinal direction of the pipe. A reflecting mirror that has first and second reflecting mirror surfaces having different inclinations, emits ultrasonic waves toward the tube wall through the reflecting mirror surface while rotating around the rotation axis, and receives ultrasonic echoes from the tube wall; , A rotating device for rotating the reflecting mirror around the rotation axis, and a probe for transmitting longitudinal ultrasonic waves toward the reflecting mirror parallel to the rotation axis and receiving the ultrasonic echo reflected from the reflecting mirror. And a detector capable of moving back and forth in the longitudinal direction of the tube, and an ultrasonic echo analyzing means, wherein the first reflecting mirror surface is provided at an inclination angle of 45 ° with respect to the rotation axis, and the probe The ultrasonic wave incident from is reflected perpendicularly to the tube wall, and the second reflecting mirror surface is It is provided at an oblique angle θ, reflects the ultrasonic wave incident from the probe, and makes it obliquely incident on the tube wall at a predetermined incident angle Φ exceeding the longitudinal wave critical angle to generate the transverse ultrasonic wave in the tube wall. The first reflecting mirror surface and the second reflecting mirror surface are arranged so as to have reflecting mirror regions that do not overlap each other with respect to the incident direction of the ultrasonic wave, and at predetermined intervals along the rotation axis. An automatic tube crack detection device, which is arranged. 2. The first reflecting mirror surface and the second reflecting mirror surface,
Each of the first and second reflecting mirror surfaces has a non-overlapping reflecting mirror region of at least 1/4 or more of the ultrasonic wave incident surface with respect to the incident direction of the ultrasonic wave.
20mm at intervals where the point of incidence of the ultrasonic wave on the tube wall becomes the same position
2. The automatic tube crack detection device according to claim 1, wherein the tubes are arranged along the rotation axis at intervals of the following lengths. 3. A reflecting mirror rotation detecting means which is provided at a tip of the detector and detects a head of an ultrasonic echo for each rotation of the reflecting mirror; 3. The automatic tube crack detecting apparatus according to claim 1, further comprising an encoder for detecting a direction position, wherein the position where the crack occurs is detected by cooperation of the reflecting mirror rotating means and the encoder. 4. The automatic tube crack detecting device according to claim 1, wherein the rotating device is an ultrasonic motor. 5. A flow path for feeding water for filling an ultrasonic propagation path in a tube with water, an electric wire for supplying power to an ultrasonic motor, and a signal between a probe and a pulsar receiver. An exchange cable is connected to the detector, the flow path,
5. The automatic tube crack detection device according to claim 4, wherein at least one of the electric wire and the cable is pulled to move the detector through the tube.