JP2001056318A - Flaw detection method of pipe by ultrasonic waves and ultrasonic flaw detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultrasonic flaw detection method and an ultrasonic flaw detector capable of detecting the flaw of a pipe body over the total periphery thereof within the narrow moving range of a probe. SOLUTION: A flaw detector 20 is equipped with the frame body movable on the surface of a pipe body in the pipe axis direction thereof, a peripheral position adjusting mechanism 24 for regulating the positions of a transmitting probe 21 and a receiving probe 22 in the peripheral direction of the pipe body, the peripheral angle adjusting mechanism 25 supported on the frame body 29 in a rotatable manner and supporting the transmitting probe 21 emitting ultrasonic waves toward a pipe wall and the receiving probe 22 receiving the ultrasonic beam transmitted through the pipe wall and a peripheral moving mechanism 26 for moving the frame body in the direction crossing the pipe axis of the pipe body at a right angle over a predetermined range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piping inspection method and apparatus using ultrasonic waves, and more particularly to a piping inspection method and apparatus suitable for detecting a thinned portion due to corrosion of a long pipe. .

[0002]

2. Description of the Related Art In a chemical plant, a large number of pipes for transporting various liquid raw materials and fuels are used, and steel pipes are often used as those pipes. Of these, those that are piped outdoors will corrode over a long period of time, so it is imperative to discover them before corrosion progresses and leaks occur to prevent accidents. is there. Although the thickness of the steel pipe is reduced by corrosion of the steel pipe, there is an inspection method using an ultrasonic wave as a means for detecting the thinned portion.

FIG. 1 shows a general pipe thickness inspection method using ultrasonic waves. As shown in FIG. 1, an ultrasonic thickness gauge probe 2 is arranged on the wall surface of a pipe, and the wall thickness is measured to detect a thinned portion. The ultrasonic thickness gauge probe 2 emits an ultrasonic beam from the surface of the tube 1 toward the inner surface, and measures the reflected wave from the inner surface to measure the wall thickness, so that the wall thickness can be accurately measured.

FIG. 2 shows another method. FIG. 2A shows a so-called reflection method in which a transmission / reception probe 3 having a transmission / reception unit for transmitting / receiving ultrasonic waves at a predetermined inclination angle with respect to the tube axis is arranged on the surface of the tube to transmit / receive ultrasonic waves. Thus, an abnormal portion of the pipe wall portion, for example, a thinned portion or a crack is detected. In this method, the presence of an abnormal part is detected by detecting a reflected beam in which an ultrasonic beam incident at an angle to the tube axis is reflected at an abnormal part and returns to a transmitting / receiving part.

FIG. 2B shows a so-called transmission method, in which a transmission probe 4 for transmitting and receiving ultrasonic waves at a predetermined inclination angle with respect to the tube axis is arranged at a predetermined distance on the surface of the tube. This is a method of using the reception probe 5 and grasping the change in the transmission path of the sound wave from the properties of the ultrasonic waves reaching the reception probe 5, particularly the attenuation state. As shown in the figure, if an abnormal change such as corrosion occurs in the portion "A", the sound wave reaching the receiving probe 5 has a shorter sound wave transmission time than the reflection at "B".
In addition, when the “A” part has significant irregularities due to corrosion or the like, it is scattered,
Sound waves reaching the receiving probe are attenuated and weakened. The change in the plate thickness can be quantitatively grasped by these degrees. This method is also used in the circumferential direction of a curved tube.

FIG. 3 shows an example in which a transmission / reception probe for receiving an incident ultrasonic wave while rotating it is used. In this case, the transmission / reception probe 6 uses a probe 9 in which a transmission vibrator 7 and a reception vibrator 8 are integrally provided, and transmits an ultrasonic wave circulating at substantially the same position as the incident position of the transmission vibrator 7. The receiving oscillator 8 receives the signal.

[0007]

In the method using the ultrasonic thickness gauge probe 2 shown in FIG. 1, the thickness of the pipe is measured, and the thickness of the pipe is measured over the entire length of the pipe. In order to inspect the tube, it is necessary to move the ultrasonic thickness gage probe 2 relative to the entire circumference of the tube 1 and the entire length of the tube for scanning. Therefore, in a pipe of a chemical plant or the like, it is often difficult to scan the thickness probe over the entire circumference of the outer surface of the pipe, because a gantry or the like supporting the pipe is present.

In the method shown in FIG. 2A, a specific range of the side surface of the tube can be inspected. However, since the reflected beam is received at the same position as the transmission position, the reflected beam is transmitted to the peripheral side surface of the tube. There is a limit to the range for accurately detecting the reflected beam. The method of FIG. 2 (b) is a method of emitting an ultrasonic beam in the axial direction of the tube and detecting a beam arriving at a predetermined position on the axis, and is capable of inspecting a certain area of the tube wall. . In order to inspect the entire circumference of the tube, it is necessary to move it over a considerable area in the circumferential direction. Similarly, the method of emitting an ultrasonic beam in the circumferential direction and detecting the ultrasonic beam in the circumferential direction also requires moving over the entire circumference in order to inspect the entire circumference.

In the case where ultrasonic waves are transmitted from the surface of the tube and transmitted to the entire circumference of the tube, as shown in FIG. 4, the ultrasonic waves are repeatedly transmitted on the inner and outer surfaces of the tube. . In this type of inspection, since the incident ultrasonic wave has a strong directivity that is not uniformly diffused when entering the tube, as shown in FIG. 4, it passes through the incident position and the circumference. The arrival position on the outer circumference that has been circulated depends on the diameter and thickness of the tube. Therefore, when using a probe in which the transmitting transducer and the receiving transducer shown in FIG. 3 are integrally fixed, it is necessary to prepare a probe in accordance with the type of tube diameter and wall thickness.

Further, the probe is actually limited in size in terms of shape, and cannot always be arranged at the orbital reaching position theoretically specified in FIG. In this case, it can be imagined that the signal is received at the position 'in FIG. 4, that is, at the outer surface reflection position in the second round, but there is a possibility that interference occurs with the arrival wave of the incident wave. As a method for solving this, as shown in FIG. 5, the transmission probe 11 and the reception probe 12 are connected to the tube 1.
A method of disposing them integrally in a displaced manner in the tube axis direction can be considered. However, in this method, if the incident direction of the ultrasonic wave is the direction perpendicular to the tube axis, that is, the direction of the circumferential cross section, the beam reaching the receiving probe is only a diverging beam, and the transmitted ultrasonic wave is the receiving probe. There is a problem that can not be accurately captured.

Further, as shown in FIG. 4, when the incident wave is made incident at a predetermined angle θ with respect to the incident position on the tube surface and the line h lowered to the central axis O of the tube, the inner surface and the outer surface And also by the ultrasonic waves that reflected and repeated around,
Even if there is a recess such as corrosion in the region between the outer surface and the inner surface in the drawing, it cannot be detected even if there is a concave portion such as corrosion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has been made in consideration of the above-described problem. It is an object of the present invention to obtain an inspection method and an apparatus therefor. Further, when inspecting using an ultrasonic probe in which an ultrasonic transmitting unit and an ultrasonic receiving unit are integrated, a tube inspection method and an ultra-small tube capable of coping with inspection of tubes having various tube diameters and tube wall thicknesses. It is an object to provide an acoustic probe.

[0013]

According to a first aspect of the present invention, an ultrasonic beam is emitted to a wall of a tube, and a transmitted beam transmitted around the tube is received to inspect the tube for damage. In the ultrasonic flaw detection method, the ultrasonic beam is incident at a predetermined angle with respect to the circumferential direction of the tube, the ultrasonic beam is transmitted in a spiral shape, and the ultrasonic receiving position is shifted from the incident position in the tube axis direction. This is a method of receiving data at a location.

According to the method of the first aspect, it is possible to efficiently receive the ultrasonic beam that has entered the tube wall and has passed through the tube wall and circulated, thereby enabling highly accurate inspection. According to a second aspect of the present invention, there is provided an ultrasonic flaw detection method in which an ultrasonic beam is emitted to a wall portion of a tube, receives a transmitted beam transmitted around the tube, and inspects the tube for damage. It is incident at a predetermined inclination angle from the surface toward the inner surface of the tubular body, and the incident part and the receiving part of the ultrasonic wave are moved from the incident position to the range of the position where it is reflected by the inner surface and reaches the outer surface first. The ultrasonic beam is transmitted over the entire circumference of the tube wall.

According to the second aspect of the present invention, it is possible to inspect the entire circumference of the pipe only by moving the ultrasonic probe over a part of the outer surface of the pipe in the circumferential direction. Become. According to a third aspect of the present invention, there is provided a frame capable of moving the surface of the tube in the axial direction of the tube, a transmitting probe supported by the frame and emitting ultrasonic waves toward the tube wall, and transmitting the tube wall. A rotatably supported probe support that supports a receiving probe that receives a transmitted ultrasonic beam, and moves the support over a predetermined range in a direction orthogonal to a pipe axis along a pipe surface. An ultrasonic flaw detector for detecting a flaw in a circumferential direction and an axial direction of a tubular body, comprising:

In the ultrasonic flaw detector according to the third aspect, the ultrasonic beam emitted from the transmitting probe is emitted at an angle inclined with respect to the circumferential direction of the tube, and the ultrasonic beam is transmitted to the tube wall in a spiral shape. , And can receive an ultrasonic beam transmitted and helically spiraled. In addition, the ultrasonic probe can be moved in the direction of the tube axis, and at the same time, can be moved in a direction perpendicular to the tube axis. Becomes possible.

According to a fourth aspect of the present invention, in the ultrasonic flaw detector of the third aspect, the transmitting probe and the receiving probe are arranged at positions shifted in the moving direction of the frame, and The probe and the receiving probe are movable parallel to each other. In the invention of claim 4, even if the diameter or the thickness of the tube to be inspected changes, the position of the transmission probe or the reception probe is relatively moved, and the ultrasonic beam orbiting around the tube wall is moved. The transmission position and the reception position can be adjusted to optimal positions.

[0018]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 6 is a diagram showing a basic configuration of an ultrasonic inspection system according to the present invention adopted to solve the above problem. The ultrasonic inspection system includes an ultrasonic flaw detector 20, a control device 30 for controlling various movements of the ultrasonic flaw detector 20, a display device 31 for displaying an inspection result, the ultrasonic flaw detector 20, and a tube as an object to be inspected. A couplant supply pump 32 for supplying a couplant to improve the state of contact with the couplant 1 is provided.

The ultrasonic flaw detector 20 includes an ultrasonic probe 23 comprising an ultrasonic transmission probe 21 and an ultrasonic probe 22;
Circumferential position adjusting mechanism 24 for transmitting probe 21 and receiving probe 22, circumferential angle adjusting mechanism 25, and circumferential moving mechanism 2
6, an axial running mechanism 27, a shoe 28 for arranging the ultrasonic flaw detector 20 on the tube, a motor for driving the axial running motor and a circumferential moving mechanism, and a position detecting encoder mechanism 33.

The control device 30 controls various movements of the ultrasonic flaw detector 20, and controls the oscillation and reception of ultrasonic waves, an image forming apparatus based on received data, a storage device, an arithmetic processing device, a traveling motor, an encoder control device, and the like. have. Further, the control device 30 has a display device 3 for displaying an inspection result.
1 is connected and the inspection result is displayed. Ultrasonic flaw detector 2
The above-mentioned various mechanisms will be described.

As described with reference to FIG. 4 described above, the circumferential position adjusting mechanism 24 depends on the diameter and wall thickness of the tube, the incident position and the arrival position on the outer circumference that has passed through the circumference. Therefore, the transmission probe 21 and the reception probe 22
The transmission probe 21 and the reception probe 22 are slidably supported in the direction of the arrow a shown in the figure. This makes it possible to make adjustments so that the return position after transmission differs from the incident point depending on the tube diameter and tube thickness. The incident position and the return position can also be adjusted by adjusting the angle (θ in FIG. 4) at which the ultrasonic wave is incident on the thick portion of the tube, and the incident angle θ of the transmission probe 21 can be adjusted. It can be adjusted.

As described with reference to FIG. 5, the circumferential angle adjusting mechanism 25 adjusts the displacement in the tube axis direction when the ultrasonic wave circulates, and moves the probe 23 around the center axis O. As shown by the arrow b, it can be rotated by a certain angle. FIG. 7 illustrates the operation of the circumferential angle adjustment mechanism 25. By rotating the probe 23, the incident direction of the ultrasonic wave from the transmission probe 21 with respect to the tube axis is shown in FIG. 7A. Can be made to incline at an angle α from the direction perpendicular to the tube axis. As a result, the ultrasonic wave propagates spirally as shown in FIG. 7B, and the receiving probe can easily receive the orbiting ultrasonic wave. That is, in the example of FIG. 7, it becomes possible to arrange the receiving probe 22 at a position shifted in the tube axis direction where the ultrasonic wave helically circulates, so that the transmitted ultrasonic wave can be efficiently received. become.

As described above with reference to FIG. 4, when the laser beam is made incident on the surface of the tube at a predetermined angle θ, the ultrasonic wave circulating around the inner surface and the outer surface by repeating reflections on the inner surface and the outer surface can also be used. The area between the outer surface and the inner surface is outside the path, so that even if there is a concave portion such as corrosion, it cannot be detected. Circumferential movement mechanism 26
In order to eliminate the area outside the path, the incident point is moved with respect to the outer surface of the tube by a predetermined range in a direction perpendicular to the tube axis as shown by an arrow c in FIG. This movement range is a range between the incident position and the position where the incident wave is reflected from the inner surface and reaches the outer surface in FIG. 4, so that the range outside the circumferential path can be eliminated.

The axial running mechanism 27 moves the ultrasonic flaw detector in the axial direction d of the tube. The ultrasonic probe 23 is disposed on the surface of the tube with a shoe 28 interposed therebetween so that ultrasonic waves emitted from the probe 23 can be efficiently transmitted to and received from the curved surface of the steel tube. Ultrasonic probe 23
Is supported by the gantry 29, and in the state of being supported by the gantry 29, the above-described various mechanisms are operated so that necessary position adjustment can be performed. Further, the ultrasonic flaw detector 20 detects a traveling motor and a circumferential slide motor for remotely driving the circumferential moving mechanism 26 and the axial traveling mechanism 27 of the probe 23 and a moving position of each mechanism. Is provided.

Next, a specific embodiment of the ultrasonic flaw detector 20 shown in FIG. 6 will be described with reference to FIGS. FIG.
Shows a main part of a support structure of the probe 23, and the probe 23 including the transmission probe 21 and the reception probe 22 is supported by a turntable 42 provided on the base 41. . The transmission probe 21 and the reception probe 22 can move in a direction indicated by an arrow a (a direction orthogonal to the tube axis), and constitute a circumferential position adjustment mechanism 24. The turntable 42 constitutes the above-described circumferential angle adjustment mechanism 25. Turntable 4
Numeral 2 is adapted to be fixed to the base 41 at a position at a predetermined rotation angle in the rotation direction b by a screw 43. The probe 23 is disposed on the outer surface of the tube 1 via a shoe 28 having a curved surface conforming to the outer diameter of the tube. The transmission probe 21 and the reception probe 22 of the probe 23 have the structure shown in FIG. 11, and the oscillation vibrator 21a (22a) is in contact with the upper surface of the shoe 28 disposed on the lower side. Placed in

Next, the circumferential moving mechanism 26 and the tube axis running mechanism 27 will be described with reference to FIGS. FIG. 9 shows a schematic configuration of the circumferential moving mechanism 26, and FIG.
0 shows a plan view and a side view of the entire ultrasonic flaw detector 20. The ultrasonic flaw detector 20 has a frame 51, and upper supports 53 that are elastically supported at four corners via springs 52 at the four corners are provided on the frame 51 so as to be vertically displaceable. A rail 54 is provided on the upper support 53, and the slide member 55 is supported by the rail 54 so as to be movable in a direction c perpendicular to the tube axis. Slide member 5
The support 41 is supported by two support rods 56 provided at two locations in the axial direction (see the side view in FIG. 10). The frame 51 is provided with a repetitive drive motor 57 for driving the circumferential moving mechanism.
Are pivotally connected by a rod 58. The base 41 has a structure in which the support bar 56 and the shaft bar 26 of the base 41 are inserted and connected, and the shaft bar 26 is arranged along the circumference of the tube with the shaft 26 as an axis in the tube axis direction. Accordingly, the rotation of the repetitive drive motor 57 allows the slide member 55 to move in the direction of arrow c with respect to the upper support 53. The probe 23 supported on the turntable 42 by the movement of the slide member 55 in the direction c.
Is c and the shoe 28 is an arrow c perpendicular to the pipe axis.
Move in the direction of. At this time, since the shoe 28 moves along the curved surface of the tube wall, the upper support 53 is vertically displaced, but this displacement is absorbed by the spring 52. The slide member 55 is provided with a circumferential movement confirmation rack 61 and a circumferential movement confirmation encoder 62 so that the amount of movement can be confirmed in the circumferential direction.

The frame 51 includes an axial traveling drive motor 7.
0, and the moving magnet wheel 7 via the belt 71
2 is driven. The frame 51 also
An auxiliary wheel 75 for axial movement is provided. Four auxiliary wheels 75 for axial movement are provided on the front, rear, left, and right sides of the frame 51 via an angle adjusting mechanism 76. Using this angle adjusting mechanism 76, the angle of the auxiliary wheel 75 for axial movement can be adjusted according to the diameter of the pipe.

The frame 51 further includes a height adjusting mechanism 8.
An axial movement amount calculation encoder 80 supported by 1 is provided so that the movement amount in the axial direction can be confirmed. An operation for performing a flaw detection inspection of a pipe using the ultrasonic inspection system having the above configuration will be described. First, prior to the inspection, data on the diameter and thickness of the tube to be inspected is obtained, and the positions of the incident position, the orbital arrival position, and the first outer surface reflection position shown in FIG. 4 are confirmed.

Based on the obtained data, the adjustment of the circumferential position adjustment mechanism 24 is performed by adjusting the positions of the transmission probe 21 and the reception probe 22. Next, the adjustment of the circumferential angle adjusting mechanism 25 is adjusted by rotating the turntable 42 on which the probe 23 is supported by a predetermined angle, and fixed by screws 43 at a predetermined rotation angle. Note that this rotation angle is as shown in FIG.
Adjustment is made so that the ultrasonic beam transmitted from the incident position and circulating reaches the receiving position shifted in the axial direction.

The above operation is executed before the ultrasonic flaw detector 20 is set on the tube wall before the flaw detection inspection. next,
The flaw detection device 20 is arranged on the tube 1, and an ultrasonic beam is emitted from the transmission probe 21 into the tube wall to perform an inspection. The ultrasonic beam that has entered and transmitted through the tube wall and circulated is received by the receiving probe 22, and the detection signal is subjected to predetermined arithmetic processing and displayed on the display device 31. The ultrasonic flaw detector 20 is moved in the tube axis direction by driving the drive motor 70 of the axial traveling mechanism 27, and at the same time, the circumferential moving mechanism 26 is also operated. The circumferential moving mechanism 26 moves the base 41 supporting the probe 23 with the shoe 28 by a circumferential driving repetition motor 57 while repeating a predetermined circumferential distance left and right. Therefore, the ultrasonic flaw detector 20 moves in the pipe axis direction while repeatedly moving left and right. The moving speeds of the circumferential moving mechanism 26 and the axial running mechanism 27 are determined in consideration of the beam diameter so that the ultrasonic beam penetrates all inside the tube wall. The range of movement by the circumferential movement mechanism 26 is the distance shown in FIG. 4 and is a very narrow range. This makes it possible to eliminate the range where the ultrasonic beam is out of the path inside the tube wall, and to inspect the entire circumference of the tube with a small moving range of the ultrasonic flaw detector, thereby improving the efficiency along with the axial traveling. Inspection of the whole pipe can be carried out.

The data obtained from the receiving probe 22 is subjected to arithmetic processing by the control device 30 and can be displayed on the display device 31 as an image. The arithmetic unit of the control device 30 calculates the corresponding position of the pipe using the circumferential and axial movement data obtained by the circumferential movement confirmation encoder 62 and the axial movement amount calculation encoder 80, and It can be displayed together with the data obtained.

[0032]

According to the present invention as described above, the following various effects can be realized. Without moving the probe over the entire circumference of the pipe, flaw detection of the entire circumference of the pipe can be performed only by moving in a narrow range. Therefore, a flaw detection test of a pipe laid in a plant or the like can be performed with high accuracy. Further, according to the ultrasonic flaw detector of the present invention, the drive control of the circumferential direction moving mechanism and the axial direction running mechanism can be automatically performed, and the power saving effect can be improved in use. Further, even when the diameter and the wall thickness of the tube to be inspected change, optimal positioning of the probe can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a general thickness inspection method using ultrasonic waves.

FIG. 2A shows a flaw detection method by a reflection method, and FIG.
FIG. 3 is a diagram showing a flaw detection method in a transmission method.

FIG. 3 shows a flaw detection method in which incident ultrasonic waves are circulated and received.

FIG. 4 is a diagram for explaining a transmission state of an ultrasonic beam circling the tube.

FIG. 5 is a diagram showing an example in which a transmission probe and a reception probe are arranged so as to be shifted in the tube axis direction.

FIG. 6 is a configuration diagram of an ultrasonic inspection system according to the present invention.

FIG. 7 is an explanatory diagram for spirally emitting an ultrasonic beam.

FIG. 8 is a diagram illustrating a support structure of a probe of the ultrasonic flaw detector according to the embodiment of the present invention.

FIG. 9 is a diagram illustrating a circumferential moving mechanism.

FIG. 10 is an overall configuration diagram of the ultrasonic flaw detector. (A) is a plan view, and (b) is a side view.

FIG. 11 is a diagram showing a probe.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tube 20 Ultrasonic flaw detector 21 Transmission probe 22 Reception probe 23 Probe 24 Circumferential position adjustment mechanism 25 Circumferential angle adjustment mechanism 26 Circumferential movement mechanism 27 Axial traveling mechanism 28 Shoe 29 Frame 30 Control device 31 Display device 32 Pump for supplying couplant

Claims (4)

[Claims] 1. An ultrasonic flaw detection method for emitting an ultrasonic beam to a wall of a tube, receiving a transmitted beam transmitted around the tube, and inspecting the tube for damage. An ultrasonic flaw detection method in which an ultrasonic beam is spirally transmitted by being incident at a predetermined angle with respect to the circumferential direction of the ultrasonic wave and the ultrasonic wave is received at a position shifted in the tube axis direction from the incident position. . 2. An ultrasonic flaw detection method in which an ultrasonic beam is emitted to a wall of a tube, receives a transmitted beam transmitted around the tube, and inspects the tube for damage. Incident with a predetermined inclination angle toward the inner surface of the tube,
The incident part and the receiving part of the ultrasonic wave are moved from the incident position to the position where the ultrasonic wave is reflected by the inner surface and reaches the outer surface first, so that the ultrasonic beam is transmitted over the entire circumference of the tube wall. An ultrasonic flaw detection method characterized in that: 3. A frame capable of moving the surface of the tube in the axial direction of the tube, a transmitting probe supported by the frame and emitting ultrasonic waves toward the tube wall, and transmitting and transmitting the tube wall. A rotatably supported probe support that supports a receiving probe that receives an ultrasonic beam, and a circumference that moves the support along a surface of the tube in a predetermined range in a direction perpendicular to the tube axis. An ultrasonic flaw detector for detecting flaws in a circumferential direction and an axial direction of a tubular body, comprising a direction moving mechanism. 4. The ultrasonic flaw detector according to claim 3, wherein the transmission probe and the reception probe are arranged at positions shifted in the moving direction of the frame, and the transmission probe and the reception probe are arranged. An ultrasonic flaw detector wherein the children can move in parallel with each other.