JP2017032477A - Flaw detecting device, and method, for welded parts of pipes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for flaw detection in welded parts of pipes by which the position of any flaw existing near welded parts all around a hollow pipe can be accurately located by precisely checking welded parts existing near the surface of the hollow pipe from inside and making the flaw visible.SOLUTION: A flaw detecting device is equipped with a hollow cylindrical guide rail 12 that is coaxial with and can be detachably fixed to the outer circumference surface 1a of a hollow pipe 1, a phased array probe 14 that performs transmission and reception by radially varying the direction of an ultrasonic beam S in the axial direction of the hollow pipe 1 by sector scanning, and a probe guide 16. The probe guide 16 is so configured as to hold the phased array probe 14 in such a manner as to cause the ultrasonic beam S to come incident inclined in the axial direction from the outer circumference surface 1a and to shift the phased array probe 14 in the circumferential direction along the outer circumference surface 1a following the guide rail 12.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a pipe welded part flaw detection apparatus and method for ultrasonic flaw inspection of a weld existing near the surface of a hollow pipe.

For example, in a thermal power plant, a number of hollow tubes (stub tubes or heat transfer tubes) are welded to a header (collection tube) of a boiler. Many of these hollow tubes are small diameter tubes having an outer diameter of 100 mm or less.
For example, Patent Documents 1 and 2 are disclosed as means for inspecting the welded portion of such a small-diameter pipe with ultrasonic waves.

  In “Ultrasonic flaw detection apparatus and method for small-diameter tube” in Patent Document 1, a point focus type probe includes a transducer and an acoustic medium, and an ultrasonic beam is focused near the inner surface of a tube material to be inspected. Inspection of the inside of the pipe material.

  The “ultrasonic flaw detection inspection apparatus and inspection method for small diameter pipe welds” in Patent Document 2 includes a measurement unit including an ultrasonic probe, a scanning mechanism unit, and a fixing unit. Furthermore, the ultrasonic probe includes an ultrasonic transmitter that enters the ultrasonic probe at an angle along the axial direction of the pipe to be measured, and a receiver that receives the transmitted ultrasonic wave, and inspects a welded portion of the pipe. .

JP 2012-117875 A JP 2001-74712 A

  The welded portion of the small-diameter pipe described above is, for example, a fillet welded portion where a small-diameter pipe is welded to a sleeve, and is present near the surface of the hollow tube. However, since the bead surface of the welded portion has irregularities, the probe does not contact well. Therefore, ultrasonic flaw detection from the surface side is difficult.

  Therefore, the ultrasonic flaw detection inspection of a welded portion of a small-diameter pipe in a thermal power plant is generally performed manually using a fixed-angle ultrasonic probe. In this case, the ultrasonic wave is reflected once or a plurality of times on the inner surface of the small diameter pipe and reaches the welded portion. However, since the incident angle of the ultrasonic wave is fixed, the range in which the ultrasonic wave reaches by one reflection is narrow, and the ultrasonic wave reaches the welded part by moving the probe back and forth with respect to the welded part. It is necessary to adjust to. As a result, a plurality of reflected signals and signals with different axial positions are mixed with noise in the detection signal, and it is difficult to accurately inspect the entire welded portion near the surface.

  The present invention has been developed to solve the above-described problems. That is, the object of the present invention is to accurately inspect the welds existing near the surface of the hollow tube (that is, the small-diameter pipe) from the inner surface side to visualize defects present near the welds around the entire hollow tube. It is another object of the present invention to provide a pipe welded part flaw detection apparatus and method capable of accurately grasping the position.

According to the present invention, a pipe welded part flaw detection apparatus for performing ultrasonic flaw detection on a welded part existing near the surface of a hollow pipe,
A hollow cylindrical guide rail that is coaxially and detachably fixable to the outer peripheral surface of the hollow tube;
A phased array probe for transmitting and receiving by changing the direction of the ultrasonic beam radially in the axial direction of the hollow tube by sector scanning;
A probe that holds the phased array probe so that the ultrasonic beam is incident in the axial direction from the outer peripheral surface and is movable along the outer peripheral surface along the outer peripheral surface along the guide rail. There is provided a tube welded flaw detection device including a touch guide device.

  An angle detector configured to detect a rotation angle of the circumferential direction of the phased array probe with respect to the hollow tube;

  A visualization device is provided that visualizes the inside of the hollow tube by limiting the number of reflections on the inner surface of the tube to one from the transmission / reception signal of the phased array probe and cutting the reception signal reflected two or more times.

The probe guide device includes a probe holder for fixing the phased array probe;
A holding ring that holds the probe holder in contact with the outer peripheral surface and is movable in the circumferential direction along the outer peripheral surface;
The probe holder includes a contact surface that contacts the outer peripheral surface of the hollow tube, a fixed surface that is inclined in the axial direction with respect to the contact surface and fixes the phased array probe, and a guide rail. A guide groove that guides the probe holder so as to be movable in the circumferential direction along the outer peripheral surface.

The holding ring is configured to hold the probe holder in contact with the outer peripheral surface;
A semicircular ring that is detachably connected to the holding portion and holds the hollow tube between the probe holder,
A magnet that is provided at a boundary between the holding portion and the semicircular ring and biases the probe holder toward the outer peripheral surface;

Moreover, according to the present invention, there is provided a tube welded portion flaw detection method for ultrasonic flaw detection of a weld existing in the vicinity of the surface of a hollow tube,
A hollow cylindrical guide rail is coaxially and detachably fixed to the outer peripheral surface of the hollow tube,
A probe guide device to which a phased array probe is fixed is attached so as to be movable in the circumferential direction along the outer peripheral surface following the guide rail,
The sector scan of the phased array probe changes the direction of the ultrasonic beam radially in the axial direction of the hollow tube, and transmits and receives the probe guide device along the guide rail. A method for flaw detection of a welded portion of a pipe is provided.

  An angle detector detects a circumferential rotation angle of the phased array probe with respect to the hollow tube.

  The visualization device limits the number of reflections on the inner surface of the tube from the transmission / reception signal of the ultrasonic beam to one, cuts the reception signal reflected two or more times, and visualizes the inside of the hollow tube.

According to the above-described apparatus and method of the present invention, a hollow cylindrical guide rail can be coaxially and detachably attached to the outer peripheral surface of the hollow tube that is separated from the welded portion near the surface of the hollow tube by an optimum distance for inspection. Secure to.
In addition, the probe guide device holds the phased array probe so that the ultrasonic beam is incident on the outer peripheral surface while being inclined in the axial direction.

  Therefore, the phased array probe is positioned at the optimum position for inspection from the weld by the guide rail and the probe guide device, and the direction of the ultrasonic beam is changed to the axis of the hollow tube by the sector scan of the phased array probe. Transmission and reception can be performed by changing the direction radially. As a result, the ultrasonic beam is reflected once on the inner surface of the hollow tube and reaches the vicinity of the weld, and the reflected wave is also reflected and received once on the inner surface of the hollow tube. From the time difference, the welded portion present in the vicinity of the surface of the hollow tube can be accurately inspected from the inner surface side.

  In addition, the probe guide device can move the phased array probe in the circumferential direction along the outer peripheral surface along the guide rail. Thereby, the welding part which exists in the surface vicinity of a hollow tube over the perimeter of a hollow tube can be test | inspected correctly from an inner surface side.

  Therefore, it is possible to visualize the defects existing in the vicinity of the welded portion of the entire circumference of the hollow tube and accurately grasp the position.

It is a schematic diagram of the hollow tube which this invention makes object. 1 is an overall configuration diagram of a pipe welded portion flaw detector according to a first embodiment of the present invention. They are AA arrow directional view (A) of FIG. 2, and sectional drawing (B) in the BB line. It is a principle diagram of the present invention. It is explanatory drawing of the pipe weld part flaw detection method by this invention. It is a figure which shows the range of the visualization image inside the hollow tube obtained by this invention. It is a block diagram of the pipe welding part flaw detector of 2nd Embodiment by this invention. It is a figure which shows the visualization image of the axial direction cross section obtained using the pipe welding part flaw detector of this invention. It is a figure which shows the visualization image of the circumferential direction cross section obtained using the pipe welding part flaw detector of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In each figure, common portions are denoted by the same reference numerals, and redundant description is omitted.

1A and 1B are schematic views of a hollow tube 1 to which the present invention is directed, wherein FIG. 1A is a cross-sectional view orthogonal to the axis ZZ, and FIG. 1B is a side cross-sectional view.
The hollow tube 1 is preferably a small-diameter tube having an outer diameter of 100 mm or less, but may be a larger-diameter tube having a larger diameter. The wall thickness of the hollow tube 1 is preferably 3 mm or more and 15 mm or less, but may be more.
The material of the hollow tube 1 is preferably a steel tube or a stainless tube. However, other metals such as aluminum, titanium, and other alloys may be used.

  As shown in FIG. 1A, the cross-sectional shape of the hollow tube 1 (cross-sectional shape orthogonal to the axis ZZ) is a circular tube having a concentric outer diameter and inner diameter, and has a constant thickness. preferable. However, the part may not be a perfect circle, or the wall thickness may partially change.

  As shown in FIG. 1B, in this example, a part of the hollow tube 1 is inserted into the sleeve 2, and fillet welding is performed between the end surface of the hollow tube 1 and the hollow tube 1. The inner diameter of the sleeve 2 is larger than the outer diameter of the hollow tube 1, and a gap 3 exists between them. The welded portion 4 (fillet welded portion) is formed all around so as to fill the gap 3. The defect of the welded portion 4 is usually present at or near the welded portion 4 as indicated by C (broken line ellipse) in FIG.

In this example, the welded portion 4 has a circular shape orthogonal to the axis ZZ of the hollow tube 1. However, the present invention is not limited to this, and the welded portion 4 may be inclined to the axis ZZ of the hollow tube 1 or may be curved in the axial direction.
The material of the welded portion 4 may be the same or similar metal as the hollow tube 1 or other alloy.

  FIG. 2 is an overall configuration diagram of the pipe welded portion flaw detector 10 according to the first embodiment of the present invention. 3 is a cross-sectional view taken along the line A-A in FIG.

  2 and 3, a pipe welded portion flaw detection apparatus 10 according to the present invention is an apparatus for ultrasonic flaw detection inspection of a welded portion 4 existing near the surface of a hollow tube 1, and includes a guide rail 12, a phased array probe. 14 and a probe guide device 16.

  The guide rail 12 has a hollow cylindrical shape, and is configured to be coaxially and detachably fixed to the outer peripheral surface 1 a of the hollow tube 1. In this example, the guide rail 12 has an annular shape surrounding the outer peripheral surface 1a in a plane orthogonal to the axis ZZ. However, when the welded portion 4 is inclined or curved in the axial direction with respect to the axis ZZ of the hollow tube 1, it may be similarly inclined or curved.

  As shown in FIG. 3A, in this example, the guide rail 12 includes semicircular rings 12a and 12b, a rotating shaft 12c, and a fixing bolt 12d.

  The two semicircular rings 12 a and 12 b are semicircular arc members whose inner diameter is the same as or substantially the same as the outer diameter of the hollow tube 1. Moreover, although the cross-sectional shape of the semicircular rings 12a and 12b is rectangular in this example, it may be other than rectangular.

  The rotating shaft 12 c connects one end portions (left end portions in FIG. 3) of the two semicircular rings 12 a and 12 b so as to be rotatable around an axis parallel to the axis ZZ of the hollow tube 1. The fixing bolt 12d connects the other end portions (right end portion in FIG. 3) of the two semicircular rings 12a and 12b in a direction orthogonal to the axis ZZ of the hollow tube 1.

  The material of the semicircular rings 12a and 12b is preferably a plastic (for example, Duracon) softer than the hollow tube 1 so as not to damage the hollow tube 1. In addition, this invention is not limited to this, Acrylic, aluminum, and another metal may be sufficient.

  With the configuration described above, the guide bolt 12 can be easily removed from the outer peripheral surface 1a of the hollow tube 1 by removing the fixing bolt 12d and turning the two semicircular rings 12a and 12b in opposite directions around the rotating shaft 12c. Can be removed.

  On the other hand, when the guide rail 12 is attached, the two semicircular rings 12a and 12b are turned in the same direction around the rotating shaft 12c, and the semicircular rings 12a and 12b are formed on the outer peripheral surface 1a of the hollow tube 1. Adhere the inner surface. Next, the other end portions of the semicircular rings 12 a and 12 b are connected with the fixing bolt 12 d and compressed in a direction orthogonal to the axis ZZ of the hollow tube 1, so that the guide rail 12 is outer peripheral surface of the hollow tube 1. It can be firmly fixed to 1a.

  When the inner diameters of the semicircular rings 12a and 12b are larger than the outer diameter of the hollow tube 1 and a gap is generated between them, a member (flat plate or arc plate) corresponding to the gap may be sandwiched therebetween.

The phased array probe 14 performs transmission / reception by changing the direction of the ultrasonic beam S (see FIG. 4) radially in the axial direction of the hollow tube 1 by sector scanning. The ultrasonic beam S is preferably a transverse wave.
“To change radially in the axial direction of the hollow tube 1” means an incident angle at which the ultrasonic beam S enters the outer peripheral surface 1 a of the hollow tube 1 in a plane including the axis ZZ of the hollow tube 1. Means to change.
The phased array probe 14 includes a plurality of (many) transducers, independently controls the timing at which each transducer transmits and receives the ultrasonic beam S, and forms a synthesized ultrasonic wavefront to generate ultrasonic waves. The incident direction of the beam S is changed.

  In this example, each transducer of the phased array probe 14 is used for both transmission and reception. The present invention is not limited to this configuration. Transmitting and receiving vibrators may be provided separately.

2 and 3, the outer shape of the phased array probe 14 is a rectangular parallelepiped, and ultrasonic waves are transmitted and received radially from the lower surface thereof. A control cable 14a is fixed on the upper surface, and a control signal is input / output via the control cable 14a.
The outer shape is not limited to a rectangular parallelepiped, and may be any shape that can maintain performance.

  The probe guide device 16 holds the phased array probe 14 so that the ultrasonic beam S (see FIG. 4) is incident on the outer peripheral surface 1a at an inclination, and follows the guide rail 12 on the outer peripheral surface 1a. It is comprised so that a movement in the circumferential direction is possible along.

  2 and 3, the probe guide device 16 includes a probe holder 17 and a holding ring 18.

The phased array probe 14 is fixed to the probe holder 17.
In this example, the probe holder 17 includes a contact surface 17a, a fixed surface 17b, and a guide groove 17c. The material of the probe holder 17 is preferably made of a plastic resin such as acrylic, polyimide, or polyetherimide suitable for propagation of the ultrasonic beam S without damaging the hollow tube 1.

  The contact surface 17 a is in contact with the outer peripheral surface 1 a of the hollow tube 1. As shown in FIG. 3B, in this example, the contact surface 17a is an arc surface that is the same as or substantially the same as the outer diameter of the hollow tube 1, and is in close contact with the outer peripheral surface 1a.

  The fixed surface 17b is inclined in the axial direction with respect to the contact surface 17a, and fixes the phased array probe 14. In this example, the inclination angle of the fixed surface 17 b is set to about 47 ° (preferably 47.1 °) with respect to the axis ZZ of the hollow tube 1. The reason for this will be described later.

  Further, in this example, the probe holder 17 has a rectangular hole 17d for housing the phased array probe 14 in a part thereof. The fixed surface 17b corresponds to the bottom surface of the rectangular hole 17d. The probe holder 17 accommodated in the rectangular hole 17d is fixed in close contact with the contact surface 17a by a fixing screw 24a.

The guide groove 17c guides the probe holder 17 along the guide rail 12 so as to be movable along the outer peripheral surface 1a in the circumferential direction. The inner surface shape of the guide groove 17c is preferably the same as the cross-sectional shape of the semicircular rings 12a and 12b, and in this example is a rectangular shape.
The guide groove 17c is not limited to this example, and the probe holder 17 can be moved along the outer peripheral surface 1a in the circumferential direction along the guide rail 12 with the posture of the probe holder 17 maintained. As long as possible, other structures (for example, a guide structure using a bearing) may be used.

  In FIG. 3B, the holding ring 18 has a pair of holding portions 18a, a semicircular ring 18b, and a plurality of magnets 18c.

The pair of holding portions 18a are firmly fixed to both side surfaces of the probe holder 17 by bolts 18d, and hold the probe holder 17 in contact with the outer peripheral surface 1a.
The semicircular ring 18b is detachably connected to the pair of holding portions 18a by the magnet 18c, and holds the hollow tube 1 between the probe holder 17 and the semicircular ring 18b.

  The material of the holding portion 18a and the semicircular ring 18b may be plastic (for example, Duracon) that does not damage the hollow tube 1 and smoothly slides along the outer peripheral surface 1a of the hollow tube 1. In addition, this invention is not limited to this, Acrylic, aluminum, and another metal may be sufficient.

A plurality (in this example, 12) of magnets 18c are provided at the boundary between the holding portion 18a and the semicircular ring 18b, respectively (three in this example), and the probe holder 17 is attached to the outer peripheral surface 1a. Rush. In this example, the magnet 18c is a cylindrical permanent magnet, and is accommodated in a fitting hole provided in the holding portion 18a and the semicircular ring 18b and fixed by friction.
The present invention is not limited to the magnet 18c, and other means (for example, a spring) may be used as long as the probe holder 17 can be biased toward the outer peripheral surface 1a.

  2 and 3, the pipe welded portion flaw detector 10 of the present invention further includes an angle detector 20 and a visualization device 22.

The angle detector 20 detects the circumferential rotation angle of the phased array probe 14 with respect to the hollow tube 1.
In this example, the angle detector 20 is a rotary encoder fixed to the probe holder 17. The detection wheel 20 a rotates in contact with the outer peripheral surface 1 a of the hollow tube 1, and the phased array with respect to the hollow tube 1 is rotated. The circumferential rotation angle of the probe 14 is detected and a detection signal is output.
The configuration of the angle detector 20 is not limited to this example, and may be another known sensor or another structure.

  The visualization device 22 visualizes the inside of the hollow tube 1 by limiting the number of reflections on the inner surface of the tube from the transmission / reception signal of the phased array probe 14 to one and cutting the reception signal reflected two or more times. In this example, the visualization device 22 includes a control device 22a and an image processing device 22b.

  The control device 22a controls the phased array probe 14. That is, the control device 22a inputs a control signal to the phased array probe 14 via the control cable 14a and receives a reception signal of the phased array probe 14. The control device 22a receives the detection signal of the angle detector 20 in parallel.

  The image processing device 22b receives the transmission / reception signal of the phased array probe 14 from the control device 22a, and visualizes and outputs the welded portion 4 of the hollow tube 1 therefrom. The image processing device 22b receives the detection signal of the angle detector 20 in parallel, and visualizes and outputs the inside of the hollow tube 1 (particularly in the vicinity of the welded portion 4) over the entire circumference of the hollow tube. Good.

FIG. 4 is a principle diagram of the present invention.
In this figure, the center line of the ultrasonic beam S transmitted from the phased array probe 14 is indicated by reference symbols a → b → c → d. The phased array probe 14 performs transmission / reception by changing the direction of the ultrasonic beam S in the radial direction in the axial direction of the hollow tube 1 from a sign a → e to a sign a → f.

In this example, the material of the hollow tube 1 is general steel, and the material of the probe holder 17 is acrylic. The speed of sound C1 in acrylic is about 2730 m / s, and the speed of sound C2 in general steel is about 3230 m / s. In this case, when the incident angle from the acrylic is α and the refraction angle in the steel is θ, the following equation (1) is established from Snell's law.
C1 / sin α = C2 / sin θ (1)
Here, the incident angle α is α1, αa, αb in the drawing, and the refraction angle θ is θ1, θa, θb in the drawing.

  In the center line a → b → c → d of the ultrasonic beam S, the refraction angle θ1 is set to 60 ° in this example. In this case, the incident angle α1 is about 47.1 °, and the inclination angle of the fixed surface 17b for fixing the phased array probe 14 is set to this angle. Since the reflection on the inner surface of the tube is mirror-symmetric, it is the same as the refraction angle θ1.

When the thickness (thickness) of the hollow tube 1 is T, the axial distance L of the center line b → c is geometrically determined by tan θ1 × T, θ1 = 60 ° (2). .
When the position of the symbol d is the outer peripheral surface 1a of the hollow tube 1, the axial distance L of the center line b → c → d is obtained by 2 × tan θ1 × T (3). The range of the center line c → d is the main measurement range according to the present invention.

A part of the ultrasonic beam S reflected in the range of the center line c → d returns to the center line a → b → c → d and is received by the phased array probe 14.
Therefore, the position of the defect in the welded portion 4 located in the hollow tube 1 located in the center line a → b → c → d of the ultrasonic beam S, particularly in the range of the center line c → d, is determined. It can be detected from the angle (incident angle α1 and refraction angle θ1) and the time difference between transmission and reception.

In this example, the minimum refraction angle θa is 45 °, and in this case, the minimum incident angle αa is about 36.7 °. The minimum axial distance La until the ultrasonic beam S is reflected once on the inner surface of the hollow tube 1 and reaches the outer peripheral surface 1a can be obtained geometrically. In this example, the minimum axial distance La = 2 × tan θa × T.
In this example, the maximum refraction angle θb is 84 °, and in this case, the maximum incident angle αb is about 57.2 °. The maximum axial distance Lb until the ultrasonic beam S is reflected once on the inner surface of the hollow tube 1 and reaches the outer peripheral surface 1a can also be obtained geometrically.
Therefore, in the range from the minimum incident angle αa to the maximum incident angle αb, the axial distance until the ultrasonic beam S is reflected once by the inner surface of the hollow tube 1 and reaches the outer peripheral surface 1a is obtained geometrically. be able to.

The angle of the ultrasonic beam S by the phased array probe 14 changes at a pitch of about 0.5 °, for example, in the range from the minimum incident angle αa to the maximum incident angle αb.
Therefore, the defect position inside the hollow tube 1 located within this range can be detected from the angle of the ultrasonic beam S and the transmission / reception time difference.

  FIG. 5 is an explanatory diagram of a method for flaw detection of a pipe weld according to the present invention using the pipe weld flaw detector 10 described above. In this figure, (A) is a cross-sectional view including the axis ZZ of the hollow tube 1, and (B) is a view taken along the line CC of (A).

In FIG. 5A, the measurement side end face 17 e of the probe holder 17 is formed perpendicular to the axis ZZ of the hollow tube 1. The measurement side end face 17 e is an end face on the side close to the welded portion 4. Note that the measurement side end face 17e may not be vertical.
Further, a taper portion 17f inclined inward is provided at the lower end portion of the measurement side end face 17e. The tapered portion 17f is provided in order to avoid interference with the welded portion 4.

Further, as shown in FIG. 5B, the measurement side end face 17e and the taper portion 17f are provided with a number of grooves 25 extending in the vertical direction in the figure. The cross-sectional shape of the groove 25 is triangular in this example, but may be other shapes. With this groove 25 (preferably a triangular groove), the ultrasonic beam S is scattered on the measurement side end face 17e or the taper part 17f, and the noise of the reception signal received by the phased array probe 14 can be reduced.
It is preferable to further reduce the reflection of the ultrasonic beam S by adhering or coating a resin close to the material of the probe holder 17 on the outer surface of the groove 25.

  The pipe welded portion flaw detection method according to the present invention is a method for ultrasonic flaw detection inspection of the welded portion 4 existing near the surface of the hollow tube 1 described above.

  In the method of the present invention, first, a hollow cylindrical guide rail 12 is coaxially and detachably fixed to the outer peripheral surface 1 a of the hollow tube 1. At this time, the fixed position of the guide rail 12 is such that the axial distance L of the center line b → c → d in FIG. 4 is located near the center of the measurement range, and between the minimum axial distance La and the maximum axial distance Lb. Set the measurement range.

  Next, the probe guide device 16 to which the phased array probe 14 is fixed is attached so as to be movable along the outer peripheral surface 1 a along the guide rail 12.

  At this time, a liquid contact medium is applied between the phased array probe 14 and the fixed surface 17b and between the probe holder 17 and the outer peripheral surface 1a. Further, the probe holder 17 is biased toward the outer peripheral surface 1a by the magnet 18c. The propagation efficiency of the ultrasonic beam S from the phased array probe 14 to the inside of the hollow tube 1 through the probe holder 17 can be increased by urging by the contact medium and the magnet 18c.

  Next, in this state, by the sector scan of the phased array probe 14, the direction of the ultrasonic beam S is changed radially in the axial direction of the hollow tube 1, and the probe is copied along the guide rail 12. The guide device 16 is moved in the circumferential direction along the outer peripheral surface 1a.

Further, the angle detector 20 detects the circumferential rotation angle of the phased array probe 14 with respect to the hollow tube 1.
Further, the inside of the hollow tube 1 is visualized from the transmission / reception signal of the ultrasonic beam S by the visualization device 22.

FIG. 6 is a diagram showing the range of the visualized image inside the hollow tube obtained by the present invention.
As shown in FIG. 4, since the reflection of the ultrasonic beam S on the inner surface of the tube is mirror-symmetric, the hollow tube 1, the outer peripheral surface 1a, the welded portion 4, and the sleeve detected by reflection once on the inner surface of the tube. 2 is detected as a hollow tube 1 ′, an outer peripheral surface 1a ′, a welded portion 4 ′, and a sleeve 2 ′ of the mirror image.
In addition, the number of reflections on the inner surface of the tube is limited to one, and the received signal of the ultrasonic beam S reflected two or more times is cut, so that the range of the visualized image inside the hollow tube is the hatched range shown in FIG. can do.

FIG. 7 is a configuration diagram of the pipe welded portion flaw detector 10 according to the second embodiment of the present invention.
In this figure, (A) shows the side surface shape of the phased array probe 14, and (B) shows a state in which the phased array probe 14 is fixed to the probe holder 17.
As shown in this example, the outer shape of the phased array probe 14 may be any shape that can maintain performance.
Other configurations of the second embodiment are the same as those of the first embodiment described above.

  FIG. 8 and FIG. 9 are diagrams illustrating an example of a visualized image obtained using the pipe welded portion flaw detector 10 according to the first embodiment described above. This example is a test result of the hollow tube 1 having an outer diameter of 45 mm.

FIG. 8 is a visualized image of an axial section, where the horizontal axis indicates the axial distance of the hollow tube 1 and the vertical axis indicates the depth from the outer peripheral surface 1a.
In this figure, the direct range, the single reflection range, the tube inner surface, the tube outer surface (outer peripheral surface 1a ′), the welded portion 4 ′, and the detection target portion (defect portion) are clearly visualized, and the axis of the defect portion It is possible to accurately grasp the direction position and size.

FIG. 9 is a visualized image of the circumferential cross section, where the horizontal axis indicates the circumferential angle of the hollow tube 1 and the vertical axis indicates the depth from the outer peripheral surface 1a.
In this figure, the circumferential angle ranges from 0 to 360 °, and the direct-light range, the single reflection range, the tube inner surface, the tube outer surface (outer surface 1a ′), the welded portion 4 ′, and the detection target portion (defect portion) are clear. It is possible to accurately grasp the circumferential position and size of the defective portion.

According to the apparatus and method of the present invention described above, a hollow cylindrical guide rail is provided on the outer peripheral surface 1a of the hollow tube 1 which is separated from the welded portion 4 existing in the vicinity of the surface of the hollow tube 1 by an optimum distance for inspection. 12 is fixed coaxially and detachably.
Further, the probe guide device 16 holds the phased array probe 14 so that the ultrasonic beam S is incident on the outer peripheral surface 1a while being inclined in the axial direction.

  Therefore, the phased array probe 14 is positioned at the optimum position for inspection from the welded portion 4 by the guide rail 12 and the probe guide device 16, and the direction of the ultrasonic beam S is determined by sector scanning of the phased array probe 14. Can be transmitted / received by changing them radially in the axial direction of the hollow tube 1. As a result, the ultrasonic beam S is reflected once on the inner surface of the hollow tube 1 and reaches the vicinity of the weld, and the reflected wave is also reflected once on the inner surface of the hollow tube 1 and received. With the above configuration, the welded portion 4 existing near the surface of the hollow tube 1 can be accurately inspected from the inner surface side from the angle of the ultrasonic beam S and the time difference between transmission and reception.

  In addition, the probe guide device 16 can move the phased array probe 14 in the circumferential direction along the outer peripheral surface 1 a along the guide rail 12. Thereby, the welding part 4 which exists in the surface vicinity of the hollow tube 1 over the perimeter of a hollow tube can be test | inspected correctly from an inner surface side.

  Therefore, it is possible to visualize the defects existing in the vicinity of the welded portion of the entire circumference of the hollow tube and accurately grasp the position.

  In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously in the range which does not deviate from the summary of this invention.

C1 speed of sound in acrylic, C2 speed of sound in general steel,
α, α1, αa, αb Incident angle, θ, θ1, θa, θb Refraction angle,
L, La, Lb Axial distance, S ultrasonic beam, T hollow tube thickness (thickness),
Z axis of hollow tube, 1 hollow tube (small diameter tube), 1a outer peripheral surface, 2 sleeve,
3 gap, 4 welds, 10 tube welds flaw detector, 12 guide rails,
12a, 12b semi-circular ring, 12c rotating shaft, 12d fixing bolt,
14 phased array probe, 14a control cable,
16 probe guide device, 17 probe holder, 17a contact surface,
17b fixed surface, 17c guide groove, 17d rectangular hole, 17e measurement side end surface,
17f taper part, 18 holding ring, 18a holding part,
18b semi-circular ring, 18c magnet, 18d bolt,
20 Angle detector (rotary encoder), 20a detection wheel,
22 visualization device, 22a control device, 22b image processing device,
24a fixing screw, 25 grooves

Claims (8)

A welded pipe flaw detector for ultrasonic flaw inspection of a weld existing near the surface of a hollow tube,
A hollow cylindrical guide rail that is coaxially and detachably fixable to the outer peripheral surface of the hollow tube;
A phased array probe for transmitting and receiving by changing the direction of the ultrasonic beam radially in the axial direction of the hollow tube by sector scanning;
A probe that holds the phased array probe so that the ultrasonic beam is incident in the axial direction from the outer peripheral surface and is movable along the outer peripheral surface along the outer peripheral surface along the guide rail. A tube welded flaw detection device comprising: a tactile guide device.   The tube welded part flaw detection apparatus according to claim 1, further comprising an angle detector that detects a circumferential rotation angle of the phased array probe with respect to the hollow tube.   From the transmission / reception signal of the phased array probe, the number of reflections on the inner surface of the tube is limited to one, and the reception signal reflected two or more times is cut, and a visualization device for visualizing the inside of the hollow tube is provided. The pipe welded part flaw detection apparatus according to claim 1. The probe guide device includes a probe holder for fixing the phased array probe;
A holding ring that holds the probe holder in contact with the outer peripheral surface and is movable in the circumferential direction along the outer peripheral surface;
The probe holder includes a contact surface that contacts the outer peripheral surface of the hollow tube, a fixed surface that is inclined in the axial direction with respect to the contact surface and fixes the phased array probe, and a guide rail. The tube welded part flaw detection apparatus according to claim 1, further comprising a guide groove that guides the probe holder so as to be movable in the circumferential direction along the outer peripheral surface. The holding ring is configured to hold the probe holder in contact with the outer peripheral surface;
A semicircular ring that is detachably connected to the holding portion and holds the hollow tube between the probe holder,
The pipe welded part flaw detection apparatus according to claim 4, further comprising: a magnet provided at a boundary part between the holding part and the semicircular ring and biasing the probe holder toward the outer peripheral surface. A pipe weld inspection method for ultrasonic inspection of a weld existing near the surface of a hollow tube,
A hollow cylindrical guide rail is coaxially and detachably fixed to the outer peripheral surface of the hollow tube,
A probe guide device to which a phased array probe is fixed is attached so as to be movable in the circumferential direction along the outer peripheral surface following the guide rail,
The sector scan of the phased array probe changes the direction of the ultrasonic beam radially in the axial direction of the hollow tube, and transmits and receives the probe guide device along the guide rail. Tube flaw detection method that moves in the circumferential direction along   The tube welded part flaw detection method according to claim 6, wherein a circumferential rotation angle of the phased array probe with respect to the hollow tube is detected by an angle detector.   The visualization device is configured to visualize the inside of the hollow tube by limiting the number of reflections on the inner surface of the tube to one time from a transmission / reception signal of the ultrasonic beam and cutting a reception signal reflected two or more times. 6. The method for flaw detection of a pipe weld according to 6.