JP6570875B2 - Piping inspection device and piping inspection method - Google Patents

Description

  Embodiments described herein relate generally to a pipe inspection apparatus and a pipe inspection method.

  Inspection of pipe thinning and corrosion is performed using, for example, an ultrasonic flaw detection method. In the ultrasonic flaw detection method, a probe that transmits and receives ultrasonic waves is pressed against the surface of a test object, and ultrasonic waves of various frequencies are propagated inside the test object. And the ultrasonic wave (echo) which reflected and returned by the defect in a to-be-tested object and the back surface of a to-be-tested object is received, and the state inside a to-be-tested object is grasped | ascertained. The position of the defect is measured from the time required from transmission to reception of the ultrasonic wave, and the size of the defect is calculated by measuring the intensity of the received echo and the range where the defect echo appears.

  Ultrasonic inspection methods are used in nuclear power plants to measure the thickness of materials and to detect welding defects such as lamination. In addition, an ultrasonic inspection method is also used in the inspection of the weld overlay that reinforces the nozzle openings, branches, and pipe joints around the reactor pressure vessel.

  In power plants, there is a tendency for thinning to occur easily in the elbow part of the piping or the downstream side of the orifice part due to FAC (Flow Accelerated Corrosion) or erosion. Based on such knowledge, a standard (JSME S CA1-2005) for pipe thinning management has been established by the Japan Society of Mechanical Engineers (JSME). According to this standard, pipe thickness reduction management is performed by pipe thickness measurement using an ultrasonic thickness measuring instrument. However, this method requires a great deal of time and cost because it is necessary to disassemble and restore the heat insulating material covering the pipe every time the wall thickness is measured.

  Therefore, in order to realize low-cost thinning management, an embedded type fixed point measuring sensor has been developed. For example, an optical fiber EMAT method using an ultrasonic optical probe in which an electromagnetic ultrasonic transducer (EMAT) and an optical fiber sensor are combined is known. The electromagnetic ultrasonic oscillator is an oscillator that excites ultrasonic waves in a pipe by the action of electromagnetic force. The optical fiber sensor is a sensor for detecting a resonance wave of an excited ultrasonic wave with a laser beam. In the optical fiber EMAT method, by analyzing the detection result of the laser light, information on the thickness of the pipe and defects inside the pipe can be obtained.

  FIG. 1 is a perspective view for explaining a matrix fixed point method and a 3D-UT whole surface flaw detection method. FIG. 2 is a cross-sectional view for explaining the pipe thinning phenomenon.

  In the JSME thinning management standard request, as shown in FIG. 1A, in order to detect the FAC of the pipe 1, it is only necessary to measure the thickness of the pipe 1 at the matrix fixed point. Fig.1 (a) has shown the elbow part 1a of the piping 1 whose size is 150 A or more. According to the JSME pipe thinning standard, when the size of the pipe 1 is 150A or more, the axial pitch between the measurement points P is set to a length equal to or less than the pipe outer diameter. Eight (45 ° pitch) measurement points P are provided. The thickness of the pipe 1 is measured by pressing the plate thickness sensor 3 against the measurement point P.

  However, in the actual power plant piping 1, as shown in FIG. 2, not only FAC 4 but also pinhole-shaped local thinning called LDI (Liquid Droplet Impingement) 2 occurs. FIG. 2 shows an elbow 1a located downstream of the orifice 1b. In UT measurement using only matrix fixed points, there is a risk of missing such LDI2.

  Therefore, the power generation company has indicated a policy of adding to the management guideline a thickness measurement that does not cause a detection omission due to the UT entire surface flaw detection for the elbow part 1a that is likely to generate LDI2. The UT full surface flaw detection can be performed by a 3D-UT full surface flaw detection method in which the plate thickness sensor 3 is mechanically scanned as indicated by an arrow S in FIG. However, in the 3D-UT whole surface flaw detection method, it takes a long time to install and adjust the scanning mechanism. Therefore, there is a need for a pipe inspection method capable of flaw-detecting the entire elbow portion 1a in a short time.

JP 2003-130854 A JP 2005-10055 A JP 2008-281559 A

Riichiro Uchigasaki et al. “Nuclear Power and Design Technology” Taiga Publishing (1980) pp.226-250 Sasaki, Takahashi et al. "Metal thickness measurement by electromagnetic ultrasonic resonance using optical fiber Doppler sensor" welding structure symposium 2006 lecture collection (November 2006) Takahashi, Sasaki et al. "Metal pipe thickness measurement by electromagnetic ultrasonic resonance method using fiber optic Doppler" Material "The 1st Joint Lecture on Inspection, Evaluation and Maintenance" by the Maintenance Society (January 2008) Yamaya, Takahashi, Ahiko "Measurement technology of pipe thinning in thermal power plants" Toshiba review Vol.63, No.4 (2008) pp.41-44 Sasaki, Takahashi, Yamaya "Pipe thinning measurement technology by electromagnetic ultrasonic resonance method" Thermal Nuclear Power Generation No.636, Vol.60 (2009) pp.40-46

  In the optical fiber EMAT method, a plurality of ultrasonic optical probes are attached to the surface of the pipe 1, and the thickness of the pipe 1 at the installation location of these ultrasonic optical probes is measured. However, in the conventional optical fiber EMAT method, only the thickness of the pipe 1 immediately below the installation location of the ultrasonic optical probe can be measured. Therefore, in the optical fiber EMAT method, detection failure of the LDI 2 in the pipe 1 may occur. Therefore, a pipe inspection method capable of detecting FAC4 and LDI2 of the pipe 1 with high accuracy is required.

  Then, this invention makes it a subject to provide the piping inspection apparatus and piping inspection method which can test | inspect the state of piping in places other than the installation location of an ultrasonic optical probe.

  According to one embodiment, the pipe inspection apparatus includes a selection unit that selects the first and second ultrasonic optical probes from a plurality of ultrasonic optical probes attached to the pipe. Further, the apparatus supplies power to the ultrasonic oscillator of the first ultrasonic optical probe, inputs ultrasonic waves from the ultrasonic oscillator to the pipe, and transmits the ultrasonic waves through the pipe. A power supply unit configured to supply the optical fiber sensor of the second ultrasonic optical probe; The apparatus further includes a light detection unit that detects laser light transmitted through the optical fiber sensor of the second ultrasonic optical probe.

It is a perspective view for demonstrating a matrix fixed point method and 3D-UT whole surface flaw detection method. It is sectional drawing for demonstrating a pipe thinning phenomenon. It is the schematic which shows the structure of the piping inspection system of 1st Embodiment. It is the schematic which shows the structure of each ultrasonic optical probe of 1st Embodiment. It is the schematic which shows the example of attachment to piping of the ultrasonic optical probe of 1st Embodiment. It is sectional drawing and a side view for demonstrating the piping inspection method of 1st Embodiment. It is sectional drawing for demonstrating the example of the increase method of the ultrasonic propagation distance in 1st Embodiment. It is sectional drawing and a side view for demonstrating the piping inspection method of 1st Embodiment. It is a side view for demonstrating the example of the increase method of the ultrasonic reception area in 1st Embodiment. It is a figure for demonstrating the structural example of the optical fiber sensor of 1st Embodiment. It is a figure for demonstrating the LDI detection of 1st Embodiment. It is a graph for demonstrating LDI detection of 1st Embodiment. It is a figure for demonstrating the LDI detection area of 1st Embodiment. It is a figure for demonstrating the LDI detection of 1st Embodiment. It is a figure for demonstrating the LDI detection of the modification of 1st Embodiment. It is sectional drawing for demonstrating the kind of LDI of 1st Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 3 is a schematic diagram illustrating a configuration of the pipe inspection system according to the first embodiment.

  The pipe inspection system of FIG. 3 includes a plurality of ultrasonic optical probes 5 attached to the surface of the pipe 1, a pipe inspection device 6, and a computer 7. FIG. 3 shows one of these ultrasonic optical probes 5. Examples of the pipe 1 are a pipe in a nuclear power plant, a thermal power plant, a geothermal power plant, a pipeline or a water pipe.

  Each ultrasonic optical probe 5 includes an electromagnetic ultrasonic oscillator (hereinafter referred to as “EMAT”) 11 and an optical fiber sensor 12. The pipe inspection device 6 includes a light source 21, an optical interferometer 22, a waveform signal generator 23, an amplifier 24, an electrical switch 25, an optical switch 26, and a mode switch 27. The optical interferometer 22 is an example of a light detection unit. The waveform signal generator 23 and the amplifier 24 are examples of a power supply unit. The electrical switch 25, the optical switch 26, and the mode switch 27 are examples of a selection unit. The electrical switch 25 and the optical switch 26 are examples of first and second switches, respectively.

  The EMAT 11 is attached to the pipe 1 via the optical fiber sensor 12 and excites ultrasonic waves in the pipe 1 by the action of electromagnetic force. The optical fiber sensor 12 has a flexible circular plate in which a linear optical fiber is wound in a spiral shape (mosquito coil), and is used to detect a resonance wave of an excited ultrasonic wave with a laser beam. used. For example, the circular flat plate has a size similar to that of a 5-yen coin.

  The waveform signal generator 23 and the amplifier 24 generate and amplify a high frequency current under the control of the computer 7 and supply it to the EMAT 11. Thereby, electric power is supplied to EMAT11. The light source 21 generates reference laser light and supplies it to the optical fiber sensor 12. The optical interferometer 22 detects a change in the reference laser light transmitted through the optical fiber sensor 12.

  The computer 7 has a diagnostic database in which determination thresholds relating to deterioration of the pipe 1 such as corrosion and thinning of the pipe 1 are stored. The computer 7 compares the detection result of the original waveform received from the optical interferometer 22 and the processing result obtained by performing signal processing on the original waveform with the data in the diagnostic database to determine the degree of deterioration of the pipe 1.

  The piping inspection system in FIG. 3 includes a first optical fiber 31, a second optical fiber 32, and a power line 33. The first optical fiber 31 is used for transmitting laser light from the light source 21 to the optical fiber sensor 12 of each ultrasonic optical probe 5, and the second optical fiber 32 is an optical fiber of each ultrasonic optical probe 5. Used to transmit laser light from the sensor 12 to the optical interferometer 22. The power line 33 is used to supply a high-frequency current from the amplifier 24 to the EMAT 11 of each ultrasonic optical probe 5.

  The pipe inspection device 6 is connected to the electrical switch 25 provided on the power line 33, the optical switch 26 provided on the second optical fiber 32, and the first and second optical fibers 31 and 32. And a mode switch 27. The optical switch 26 may be provided on the first optical fiber 31 or may be provided on the first and second optical fibers 31 and 32.

  The electrical switch 25 is used to select the ultrasonic optical probe 5 connected to the amplifier 24 from the plurality of ultrasonic optical probes 5. When an ultrasonic optical probe 5 is selected by the electrical switch 25, a high frequency current is supplied from the amplifier 24 to the EMAT 11 of the ultrasonic optical probe 5. The electrical switch 25 of the present embodiment has 96 channels, and can control 96 ultrasonic optical probes 5.

  The optical switch 26 is used to select the ultrasonic optical probe 5 connected to the optical interferometer 22 from the plurality of ultrasonic optical probes 5. When an ultrasonic optical probe 5 is selected by the optical switch 26, laser light is supplied from the optical fiber sensor 12 of the ultrasonic optical probe 5 to the optical interferometer 22. The optical switch 26 of the present embodiment has 32 channels, and can control 32 ultrasonic optical probes 5.

  The mode switch 27 includes an ultrasonic optical probe 5 connected to the first and second optical fibers 31 and 32 that are double-tracked, and an ultrasonic optical probe that is connected to the optical fiber 41 (FIG. 10) that is single-tracked. Used for switching to 5. Details of the mode switch 27 will be described later.

  Note that the computer 7 controls the electrical switch 25, the optical switch 26, and the mode switch 27 of the present embodiment.

  FIG. 4 is a schematic diagram showing the configuration of each ultrasonic optical probe 5 of the first embodiment.

  The EMAT 11 includes a permanent magnet A1 and an electric coil A2. The permanent magnet A1 and the electric coil A2 are integrated via the resin sheet 13.

  As a factor governing the heat resistance and durability of the permanent magnet A1, there is a material of the permanent magnet A1. An example of the material of the permanent magnet A1 having good heat resistance is samarium cobalt. Since the demagnetization point of samarium cobalt is between 350 ° C. and 400 ° C., when the samarium cobalt permanent magnet A1 is used at a high temperature, it is desirable to use it at 350 ° C. or less.

  Further, from the viewpoint of considering cobalt as a rare metal, a permanent magnet A1 using an alternative material for cobalt has also been developed. For example, a samarium iron-based (Sm—Fe—N-based) permanent magnet A1 has been commercialized as a bonded magnet. If a samarium iron-based sintered magnet is used as the permanent magnet A1 in order to execute the optical fiber EMAT method which is a high temperature application, the ultrasonic optical probe 5 which is cheaper and more environmentally friendly can be realized.

  A high frequency current is supplied from the amplifier 24 to the electric coil A2. As a result, ultrasonic waves are excited inside the pipe 1 by Lorentz force and magnetostriction generated by electromagnetic induction in the electric coil A2. The high-frequency current is adjusted to have a predetermined frequency and amplitude under the control of the waveform signal generator 23 and the amplifier 24 by the computer 7. The electric coil A2 is a circular flat plate wound in an annular shape.

  The optical fiber sensor 12 is integrated with the EMAT 11 by a resin sheet 13 and an adhesive 14. The ultrasonic optical probe 5 is bonded to the pipe 1 to be measured with an adhesive 14.

  When an ultrasonic wave is input from the EMAT 11 to the pipe 1, a part of the ultrasonic wave reaches the optical fiber sensor 12. Here, when the ultrasonic wave reaches the optical fiber sensor 12 in a state where the reference laser light from the light source 21 is input to the optical fiber sensor 12, the optical fiber sensor 12 slightly expands and contracts due to the influence of the ultrasonic wave. The Doppler frequency shift and the polarization plane change occur in the laser light.

  The optical interferometer 22 detects this variation by photoelectrically converting and measuring the reference laser light transmitted through the optical fiber sensor 12. As described above, the optical interferometer 22 can detect the resonance state of the ultrasonic wave in the thickness direction through detection of the reference laser beam. The computer 7 can determine the state of the pipe 1 based on the detection result of the reference laser beam by the optical interferometer 22.

  As described above, the ultrasonic wave input from the EMAT 11 to the pipe 1 is supplied to the optical fiber sensor 12 through the pipe 1.

  At this time, the pipe inspection system of this embodiment supplies ultrasonic waves from the EMAT 11 to the optical fiber sensor 12 of the same ultrasonic optical probe 5, and the reference laser light transmitted through the optical fiber sensor 12 is transmitted by the optical interferometer 22. Can be detected. In this case, the electrical switch 25 and the optical switch 26 select the same ultrasonic optical probe 5. The computer 7 can determine the state of the pipe 1 immediately below the installation location of the ultrasonic optical probe 5 based on the detection result of the reference laser light.

  On the other hand, the pipe inspection system of this embodiment supplies ultrasonic waves from the EMAT 11 to the optical fiber sensor 12 of the different ultrasonic optical probe 5 and detects the reference laser light transmitted through the optical fiber sensor 12 by the optical interferometer 22. You can also In this case, the electrical switch 25 and the optical switch 26 select different ultrasonic optical probes 5. The ultrasonic optical probe 5 selected by the electrical switch 25 is an example of a first ultrasonic optical probe, and the ultrasonic optical probe 5 selected by the optical switch 26 is an example of a second ultrasonic optical probe. is there. The computer 7 can determine the state of the pipe 1 at a place other than the place where the ultrasonic optical probe 5 is installed based on the detection result of the reference laser light. Details of this processing will be described later.

  The ultrasonic optical probe 5 can obtain a sufficient signal intensity in measuring the thickness even if the shape of the EMAT 11 is a simple shape as shown in FIG. Factors that affect the accuracy and sensitivity of wall thickness measurement include the oscillation power of EMAT 11 and the degree of adhesion of optical fiber sensor 12 to pipe 1. Therefore, the magnetic force of the permanent magnet A1 at a high temperature and the reliability (durability) of the joint between the optical fiber sensor 12 and the pipe 1 are important.

  Regarding the magnetic force of the permanent magnet A1, there is a method of preventing oxidation of the permanent magnet A1 by using a heat-resistant permanent magnet A1 for high temperature and plating it. By using the plated high-temperature permanent magnet A1 and the polyimide-coated electric coil A2, the oscillation power of the EMAT 11 can be maintained even at high temperatures.

  On the other hand, examples of the method for joining the optical fiber sensor 12 and the pipe 1 include adhesion with a high-temperature adhesive or thermal spraying. The optical fiber sensor 12 is preferably disposed so as to be in close contact with the surface of the pipe 1 according to the surface shape and curvature of the pipe 1 and fixed to the surface of the pipe 1 by adhesion or thermal spraying. At this time, the optical fiber sensor 12 and the pipe 1 may be in direct contact with each other, or may be in close contact via an indirect material such as a flexible sheet. In the latter case, it becomes possible to improve reliability such as heat resistance and durability over a long period by increasing the bonding strength, and to perform bonding with an inexpensive material because the construction is easy.

  When bonding the polyimide-coated optical fiber sensor 12, a polyimide-based adhesive has good long-term reliability, and an epoxy-based or silicon-based adhesive tends to deteriorate relatively quickly. When the polyimide-coated optical fiber sensor 12 is bonded to the metal pipe 1, it is desirable to bond the polyimide-coated optical fiber sensor 12 by a vacuum impregnation method using a polyimide adhesive.

  In the vacuum impregnation method, first, the optical fiber sensor 12 is sandwiched between glass cloths impregnated with an adhesive. Next, a predetermined heat-curing is performed by adjusting the temperature of the heater while vacuum-packing it on the surface of the pipe 1 together with a planar heater or a rubber heater and pressing it at atmospheric pressure. Next, after curing and bonding, the release film, breather, heater, pack film, etc. are removed from the surface of the glass cloth.

  The optical fiber sensor 12 can be manufactured by the following procedure. First, a heat-resistant coated fiber is wound in a spiral shape. Next, the heat-resistant coated fiber wound in a spiral shape is fixed on a flexible sheet made of a heat-resistant material such as polyimide using a polyimide varnish. The optical fiber sensor 12 may be sandwiched between a glass cloth impregnated with an adhesive together with the flexible sheet, or may be directly sandwiched between glass cloths.

  Moreover, you may use the ceramic type adhesive agent which mix | blended the metal powder instead of the polyimide-type adhesive agent. It has been confirmed that ceramic adhesives containing metal powder have good workability and durability. When such an adhesive is used, sufficient bonding strength can be obtained by simply applying and holding the optical fiber sensor 12 on the surface of the pipe 1 and curing the adhesive at room temperature. In this case, a glass cloth may or may not be interposed between the optical fiber sensor 12 and the pipe 1.

  FIG. 5 is a schematic diagram illustrating an example of attachment of the ultrasonic optical probe 5 of the first embodiment to the pipe 1.

  In the present embodiment, the thickness of the pipe 1 is measured by attaching a plurality of ultrasonic optical probes 5 to the outer surface of the pipe 1 and analyzing by the computer 7 the resonance ultrasonic signals that are multiple-reflected from the inner surface and the outer surface of the pipe 1. To do. The material of the pipe 1 is, for example, carbon steel. In the present embodiment, by embedding the ultrasonic optical probe 5 between the pipe 1 and the heat insulating material (heat insulating material) 8 in advance, the thickness measurement (determination of deterioration) can be performed online. According to the present embodiment, since it is not necessary to disassemble and restore the heat insulating material 8 every time the wall thickness is measured, the safety of the power plant and the equipment operation rate can be increased.

  In the pipe thinning management standard, the position of the thickness measurement point of the pipe 1 is determined according to the diameter of the pipe 1. When the size of the pipe 1 is 150 A (outer diameter: about 165 mm) or more, eight locations (45 ° intervals) are determined in the circumferential direction of the pipe 1. Further, when the size of the pipe 1 is less than 150 A, four locations (90 ° intervals) are determined in the circumferential direction of the pipe 1. FIG. 5 shows an example of the former case. In addition, about the axial direction of the piping 1, it is decided to set the thickness measurement point of the piping 1 by the space | interval below the outer diameter length of the piping 1. FIG.

  A method for measuring the thickness of the pipe 1 using these ultrasonic optical probes 5 will be described.

  When a high-frequency current flows, the electric coil A2 of the EMAT 11 vibrates the pipe 1 and generates an ultrasonic wave in the pipe 1. At this time, the computer 7 sweeps the ultrasonic frequency in a desired frequency band by changing the frequency of the high-frequency current through the waveform signal generator 23.

  The ultrasonic waves in the pipe 1 propagate to the optical fiber sensor 12. When the ultrasonic wave reaches the optical fiber sensor 12 in a state where the reference laser beam is input to the optical fiber sensor 12, a Doppler frequency shift or a polarization plane fluctuation occurs in the reference laser beam. The fluctuation value (expansion / contraction speed) is converted into a voltage value by the optical interferometer 2b by photoelectric conversion, whereby the frequency of the ultrasonic wave propagating in the pipe 1 can be measured.

  When the relationship of λ = 2d is established between the thickness d of the pipe 1 and the wavelength λ of the ultrasonic wave in the pipe 1, the incident wave and the reflected wave of the ultrasonic wave resonate, and the amplitude of these combined waves Becomes larger. This relationship can be expressed as f = v / 2d using the frequency f of the ultrasonic wave in the pipe 1 and the speed of sound v. Therefore, if the frequency f and the speed of sound v of the ultrasonic wave at the time of resonance are obtained, the wall thickness d of the pipe 1 can be obtained.

  Therefore, in this embodiment, when measuring the wall thickness d of the pipe 1, the ultrasonic frequency is swept in a desired frequency band, and the resonance frequency f is measured. On the other hand, the speed of sound v can be calculated from the material of the pipe 1. Therefore, in the present embodiment, the wall thickness d of the pipe 1 can be derived using the measured resonance frequency f and the calculated sound velocity v.

  For example, in the case of a steel pipe 1 having a wall thickness of 15 mm, resonance occurs when an ultrasonic wave of 200 kHz is input. According to this embodiment, if it is known that the pipe 1 is made of steel and the resonance frequency f is 200 kHz, it can be determined that the wall thickness d of the pipe 1 is 15 mm.

  The ultrasonic optical probe 5 according to the present embodiment includes a portion considered to be statistically susceptible to thinning, such as an elbow portion or a downstream side of an orifice portion of a piping 1 of a nuclear power plant or a thermal power plant, a geothermal power plant piping, It is desirable to attach to the place etc. which are easy to raise | generate the obstruction | occlusion of the piping 1 which comprises a water pipe. In addition, the waveform signal generator 23 of the present embodiment is desirably configured so that the frequency of vibration generated in the pipe 1 can be set to an arbitrary frequency of 1 Hz to 10 MHz according to the thickness of the pipe 1. . In addition, it is desirable that the computer 7 of the present embodiment is configured to detect not only ultrasonic vibration with a frequency of 20 kHz to 10 MHz but also non-ultrasonic vibration with a frequency of 1 Hz to 20 kHz via the optical interferometer 22. .

  FIG. 5 shows the second optical fiber 32. The first and second optical fibers 31 and 32 may have exposed surfaces, may be sandwiched between members such as a resin sheet and a flexible sheet material, or may be configured by a combination thereof. Good. In addition, an adhesive may be filled in the gap between the first and second optical fibers 31 and 32 and the member sandwiching them.

(1) Pipe Inspection Method of First Embodiment FIG. 6 is a cross-sectional view and a side view for explaining the pipe inspection method of the first embodiment.

  FIG. 6A and FIG. 6B show a cross section and a side surface of one spool of the pipe 1. Specifically, an example is shown in which four rows of ultrasonic optical probes 5 are installed in a pipe 1 having a size of 150 A or more in accordance with the JSME power generation thermal equipment standard (JSME S CA1-2009). Each row includes eight ultrasonic optical probes 5 at equal intervals. The distance between these columns is set to the same value as the diameter (outer diameter) φ of the pipe 1. In this example, 32 ultrasonic optical probes 5 are installed on each spool of the pipe 1 in this way.

  In the pipe inspection system of this embodiment, an ultrasonic wave is normally supplied from the EMAT 11 to the optical fiber sensor 12 of the same ultrasonic optical probe 5, and the reference laser beam transmitted through the optical fiber sensor 12 is detected by the optical interferometer 22. . In this case, the computer 7 can measure the thickness of the pipe 1 at the place where the optical fiber sensor 12 is installed (that is, the thickness of the pipe 1 immediately below the optical fiber sensor 12).

  The piping inspection system of this embodiment can detect FAC4 (FIG. 2) of the piping 1 by such measurement. Generally, the installation interval between the ultrasonic optical probes 5 when performing the optical fiber EMAT method is set to a value that can detect the FAC 4 of the pipe 1 with sufficient accuracy.

  In the pipe inspection system of this embodiment, ultrasonic waves are supplied from the EMAT 11 to the optical fiber sensor 12 of the different ultrasonic optical probe 5, and the reference laser light transmitted through the optical fiber sensor 12 is detected by the optical interferometer 22. You can also In this case, the computer 7 can measure the thickness of the pipe 1 at a place other than the place where the optical fiber sensor 12 is installed.

  FIG. 6B shows an example in which ultrasonic waves are supplied from the EMAT 11 of the ultrasonic optical probe 5a to the optical fiber sensor 12 of the ultrasonic optical probe 5c, or an optical fiber of the ultrasonic optical probe 5d from the EMAT 11 of the ultrasonic optical probe 5b. The example which supplies an ultrasonic wave to the sensor 12 is shown. In the present embodiment, by setting various combinations of the ultrasonic optical probe 5 (EMAT11) that transmits ultrasonic waves and the ultrasonic optical probe 5 (optical fiber sensor 12) that receives ultrasonic waves, ultrasonic waves are set. It can be propagated by various routes. For example, various routes can be set so that these routes cover the surface of the pipe 1 in a mesh pattern.

  The pipe inspection system according to the present embodiment can detect a thinning or a defect of the pipe 1 in a place other than the installation place of the ultrasonic optical probe 5 by such measurement. FIG. 6B shows how the LDI 2 of the pipe 1 in such a place is detected.

  Since this LDI2 exists in the vicinity of the route connecting the ultrasonic optical probes 5a and 5c with the shortest distance, ultrasonic waves supplied from the EMAT11 of the ultrasonic optical probe 5a to the optical fiber sensor 12 of the ultrasonic optical probe 5c are transmitted. Can be detected. Further, since the LDI 2 exists in the vicinity of the route connecting the ultrasonic optical probes 5b and 5d with the shortest distance, the LDI 2 is supplied from the EMAT 11 of the ultrasonic optical probe 5b to the optical fiber sensor 12 of the ultrasonic optical probe 5d. It can also be detected using sound waves.

  Thus, the piping inspection system of this embodiment can detect both FAC4 and LDI2 of the piping 1. The piping inspection system according to the present embodiment switches the combination of the ultrasonic optical probe 5 that transmits ultrasonic waves and the ultrasonic optical probe 5 that receives ultrasonic waves by using the electrical switch 25 and the optical switch 26 to propagate ultrasonic waves. The route can be adjusted, and FAC4 and LDI2 at various locations of the pipe 1 can be detected.

  In the present embodiment, ultrasonic waves are transmitted and received between different ultrasonic optical probes 5. Therefore, it is desirable to increase the ultrasonic propagation distance of the EMAT 11 and the ultrasonic reception area of the optical fiber sensor 12. Hereinafter, a specific example of a method for increasing the ultrasonic propagation distance and the ultrasonic reception area will be described.

  FIG. 7 is a cross-sectional view for explaining an example of a method for increasing the ultrasonic propagation distance in the first embodiment.

  FIG. 7A is a cross-sectional view showing a first example of the configuration of the ultrasonic optical probe 5.

  The EMAT 11 shown in FIG. 7A includes two permanent magnets A1 and one electric coil A2. The electric coil A2 is wound in a ring shape. The outer diameter of the electric coil A2 is, for example, 15 mm. One of the permanent magnets A1 is a cylindrical magnet, and has an N pole on the electric coil A2 side and an S pole on the opposite side of the electric coil A2. The other of the permanent magnets A1 is a tube-shaped magnet surrounding a cylindrical magnet, and has an S pole on the electric coil A2 side and an N pole on the opposite side of the electric coil A2. The outer diameter of the circular tube-shaped magnet is, for example, 20 mm. The N pole and the S pole are examples of the first pole and the second pole, respectively.

  Thus, these permanent magnets A1 have opposite magnetizations. Therefore, the EMAT 11 in FIG. 7A generates a magnetic field B perpendicular to the thickness direction of the pipe 1. Therefore, a Lorentz force F perpendicular to the electric field E and the magnetic field B, that is, a Lorentz force F parallel to the thickness direction of the pipe 1 acts on the electric charge in the pipe 1. The gap between these permanent magnets A1 may be a gap, or a high permeability material such as an amorphous alloy may be inserted.

  As described above, the ultrasonic optical probe 5 in FIG. 7A can apply the magnetic field B perpendicular to the thickness direction of the pipe 1 to the pipe 1. Such a magnetic field B has an advantage that the S / N ratio of resonance in the thickness direction of the pipe 1 can be increased, for example. Therefore, according to the configuration of FIG. 7A, the resonance signal of EMAT 11 can be detected by the optical fiber sensor 12 away from the EMAT 11. According to the experiment, it was possible to detect the resonance signal between the ultrasonic optical probes 5 separated by 2φ in the axial direction and 180 ° in the circumferential direction.

  FIG. 7B is a cross-sectional view showing a second example of the configuration of the ultrasonic optical probe 5.

  The EMAT 11 in FIG. 7B includes one permanent magnet A1 and one electric coil A2. The electric coil A2 is wound in a ring shape. The outer diameter of the electric coil A2 is, for example, 30 mm. The permanent magnet A1 is a cylindrical magnet having a diameter d1 larger than the inner diameter d2 of the electric coil A2. The diameter d1 of the permanent magnet A1 is, for example, 25 mm. The thickness of the permanent magnet A1 is 5 mm, for example. The permanent magnet A1 has an S pole on the electric coil A2 side and an N pole on the opposite side of the electric coil A2.

  Therefore, the EMAT 11 in FIG. 7B generates a magnetic field B parallel to the thickness direction of the pipe 1. Therefore, a Lorentz force F perpendicular to the electric field E and the magnetic field B, that is, a Lorentz force F perpendicular to the thickness direction of the pipe 1 acts on the charge in the pipe 1.

  Moreover, EMAT11 of FIG.7 (b) is provided with the large sized permanent magnet A1 which has the diameter d1 larger than the internal diameter d2 of the electric coil A2. Such a configuration has an advantage that the intensity of the resonance signal of the EMAT 11 can be increased, for example. Therefore, according to the configuration of FIG. 7B, the resonance signal of the EMAT 11 can be detected by the optical fiber sensor 12 away from the EMAT 11.

  Thus, in this embodiment, EMAT (wide area excitation EMAT) that can excite ultrasonic waves propagating in a wide area both in the direction parallel to the thickness direction of the pipe 1 and in the direction perpendicular to the thickness direction of the pipe 1. It is desirable to use 11.

  FIG. 8 is a cross-sectional view and a side view for explaining the pipe inspection method of the first embodiment.

  8 (a) and 8 (b) show a cross section and a side surface of one spool of the pipe 1 as in FIGS. 6 (a) and 6 (b). However, FIG. 8A and FIG. 8B show an example of a pipe inspection method using the wide area excitation EMAT11.

  In the present embodiment, ultrasonic waves can be transmitted and received between the separated ultrasonic optical probes 5 by using the ultrasonic optical probe 5 including the wide area excitation EMAT11. FIG. 8B shows an example in which ultrasonic waves are supplied from the ultrasonic optical probe 5e to the ultrasonic optical probes 5f in the row adjacent to the ultrasonic optical probe 5e. FIG. 8B further shows an example in which ultrasonic waves are supplied from the ultrasonic optical probe 5e to the ultrasonic optical probes 5g in the row adjacent to the ultrasonic optical probe 5f. In this case, for example, LDI2 located between these columns can be detected.

  In this embodiment, the number of the ultrasonic optical probes 5 in each spool can be reduced by using the ultrasonic optical probes 5 including the wide-area excitation EMAT11. 8 (a) and 8 (b), four rows of ultrasonic optical probes 5 are installed in each spool, and eight ultrasonic optical probes 5 are installed in each row. Therefore, each spool has 32 ultrasonic optical probes 5.

  However, when the wide-band excitation EMAT 11 of this embodiment is used, it is possible to detect a resonance signal between the ultrasonic optical probes 5 separated by 2φ in the axial direction and 180 ° in the circumferential direction. Therefore, in this embodiment, it is possible to employ a configuration in which two rows of ultrasonic optical probes 5 are installed in each spool and two ultrasonic optical probes 5 are installed in each row. In this case, the number of ultrasonic optical probes 5 in each spool can be reduced to 1/8 (from 32 to 4).

  According to the present embodiment, it is possible to reduce the number of ultrasonic optical probes 5 installed in the pipe 1 while maintaining the measurement accuracy of the thickness of the pipe 1 (for example, ± 0.1 mm). In the present embodiment, there is a possibility that the number of ultrasonic optical probes 5 installed in the pipe 1 can be further reduced by further increasing the ultrasonic propagation distance of the EMAT 11.

  However, according to the JSME standard, it is necessary to oscillate the EMAT 11 on a matrix fixed point. Therefore, in this embodiment, the wide-area excitation EMAT 11 is installed at 32 locations of each spool, and the optical fiber sensor 12 is installed at the above-described 4 locations of each spool. These four optical fiber sensors 12 cover the entire wall thickness measurement of the spool.

  FIG. 9 is a side view for explaining an example of a method for increasing the ultrasonic wave reception area in the first embodiment.

  In the present embodiment, it is desirable to increase the number of turns of each optical fiber sensor 12 or increase the area of each optical fiber sensor 12 in order to increase the surface area of the pipe 1 covered by each optical fiber sensor 12.

  Therefore, in the present embodiment, as shown in FIG. 9, an ultrasonic optical probe 5 including an optical fiber sensor 12 wound in an oval shape may be used. In FIG. 9, the ultrasonic optical probes 5 are annularly attached around the pipe 1 for every N (N is an integer of 2 or more) ultrasonic optical probes 5. In FIG. 9, the value of N is 8. In FIG. 9, these ultrasonic optical probes 5 are attached to the pipe 1 so that the elliptical long axis is parallel to the circumferential direction of the pipe 1. The N ultrasonic optical probes 5 are preferably attached to the pipe 1 so that the optical fiber sensors 12 are in contact with or close to each other.

  According to the configuration of FIG. 9, the LDI cover ratio of each spool of the pipe 1 can be improved. For example, the LDI cover ratio can be increased to a value close to 100%. The LDI coverage is the ratio of the surface area where LDI2 can be detected to the total surface area of each spool. Details of the LDI coverage will be described later.

  Note that the shape of each optical fiber sensor 12 in FIG. 9 does not need to be a mathematically exact ellipse, and any shape that has a major axis direction and a minor axis direction and can be recognized as an ellipse is sufficient. It is. Actually, each optical fiber sensor 12 of FIG. 9 has a shape that combines two straight lines and two arcs. For example, the shape of each optical fiber sensor 12 may be oval or oval.

  In this embodiment, instead of attaching the ultrasonic optical probe 5 including the EMAT 11 and the optical fiber sensor 12 to the pipe 1, the EMAT 11 and the optical fiber sensor 12 may be separated and attached to the pipe 1. FIG. 9 shows the EMAT 11 and the optical fiber sensor 12 separated from the EMAT 11.

  In this case, a plurality of EMATs 11 and a plurality of optical fiber sensors 12 separated from these EMATs 11 are attached to the pipe 1. The electrical switch 25 is used to select the EMAT 11 connected to the amplifier 24 from these EMATs 11. The EMAT 11 selected by the electric switch 25 is an example of a first ultrasonic oscillator. The optical switch 26 is used to select the optical fiber sensor 12 connected to the optical interferometer 22 from these optical fiber sensors 12. The optical fiber sensor 12 selected by the optical switch 26 is an example of a first optical fiber sensor. The structure which isolate | separates EMAT11 and the optical fiber sensor 12 is applicable also to the LDI detection shown, for example in FIGS.

  In the present embodiment, the ultrasonic optical probe 5 including the EMAT 11 and the optical fiber sensor 12 is attached to the pipe 1, and the EMAT 11 and the optical fiber sensor 12 are separated and attached to the pipe 1. Alternatively, the optical fiber sensor 12 may be used in combination.

  FIG. 10 is a diagram for explaining a configuration example of the optical fiber sensor 12 of the first embodiment.

  FIG. 10A shows an optical fiber sensor 12 having the same structure as the optical fiber sensor 12 of FIG. The optical fiber sensor 12 of FIG. 10A has a first end B1 connected to the first optical fiber 31 and a second end B2 connected to the second optical fiber 32. .

  In the optical fiber sensor 12 of FIG. 10A, the reference laser light from the light source 21 is input to the first end B <b> 1 through the first optical fiber 31. At this time, when an ultrasonic wave reaches the optical fiber sensor 12 in a state where the reference laser light is input to the optical fiber sensor 12, a shift of the Doppler frequency or a fluctuation of the polarization plane occurs in the reference laser light.

  The reference laser light travels through the optical fiber sensor 12 toward the second end B 2, is output from the second end B 2, and is supplied to the optical interferometer 22 via the second optical fiber 32. The computer 7 can determine the state of the pipe 1 based on the detection result of the reference laser beam by the optical interferometer 22.

  On the other hand, FIG. 10B shows an optical fiber sensor 12 corresponding to this modification. The optical fiber sensor 12 in FIG. 10B has a first end B1 connected to the optical fiber 41 and a second end B2 connected to a reflection end 43 that is an example of a reflection part. . The optical fiber 41 is connected to the first and second optical fibers 31 and 32 via the circulator 42. The circulator 42 is installed to distinguish between the reference laser beam for going and returning. An example of the circulator 42 is a polarizing plate. The reflection end 43 has a reflection surface capable of reflecting the reference laser beam.

  In the optical fiber sensor 12 of FIG. 10B, the reference laser light from the light source 21 is input to the first end B1 via the optical fibers 31 and 41. At this time, when an ultrasonic wave reaches the optical fiber sensor 12 in a state where the reference laser light is input to the optical fiber sensor 12, a shift of the Doppler frequency or a fluctuation of the polarization plane occurs in the reference laser light.

  The reference laser light travels through the optical fiber sensor 12 toward the second end B2, is reflected by the reflection surface of the reflection end 43, and returns through the optical fiber sensor 12 toward the first end B1. . The reference laser beam is output from the first end B1 and supplied to the optical interferometer 22 via the optical fibers 41 and 32. The computer 7 can determine the state of the pipe 1 based on the detection result of the reference laser beam by the optical interferometer 22.

  The pipe inspection system of this embodiment can employ both the optical fiber sensor 12 in FIG. 10A and the optical fiber sensor 12 in FIG. Therefore, the pipe inspection apparatus 6 of the present embodiment has a double-track mode for using the optical fiber sensor 12 in FIG. 10A and a single-wire mode for using the optical fiber sensor 12 in FIG. A mode switch 27 for switching is provided (see FIG. 3). The double track mode and the single track mode are examples of the first mode and the second mode, respectively.

  In the single line mode of the present embodiment, for example, the circulator 42 is used. In the double track mode of the present embodiment, for example, the circulator 42 is not in use.

(2) LDI Detection of First Embodiment FIG. 11 is a diagram for explaining LDI detection of the first embodiment.

  The ultrasonic optical probe 5 of the present embodiment includes a plurality of lines L1 extending in the axial direction (z direction) on the surface of the pipe 1, and a plurality of lines L2 extending in the circumferential direction (θ direction) on the surface of the pipe 1. Are attached to the intersection P. The axial direction and the circumferential direction are examples of the first and second directions, respectively. Lines L1 and L2 are examples of first and second lines, respectively. The intersection point P corresponds to a measurement point of the matrix fixed point method.

  FIG. 11 shows an EMAT 11a arranged at a certain intersection P, an optical fiber sensor 12a arranged at an adjacent intersection P, and an LDI 2a existing on a straight line connecting the EMAT 11a and the optical fiber sensor 12a. In FIG. 11, the EMAT 11a is moved by a predetermined distance in the circumferential direction, an ultrasonic wave is input to the pipe 1 from the moved EMAT 11a, the reference laser light transmitted through the optical fiber sensor 12a is detected, and the reference laser light is detected. The mode of experiment which detects LDI2a from the result is shown. EMAT11b shows EMAT11a after movement. In this experiment, normal EMAT11 which is not wide-area excitation EMAT11 was used.

  FIG. 12 is a graph for explaining LDI detection according to the first embodiment.

  FIG. 12 shows the experimental results of FIG. FIG. 12 shows the intensity for each frequency component of the detected reference laser light. The frequency of the reference laser beam corresponds to the thickness of the pipe 1 as shown in FIG. Moreover, the numerical value of each curve of FIG. 12 shows the moving distance (mm) of EMAT11a.

  In this experiment, the pipe 1 having a wall thickness of 11.82 mm was used. A box R in FIG. 12 indicates the detection result of the LDI 2a. Thereby, it turns out that the thickness of the piping 1 of the part of LDI2a is 10.71 mm. Therefore, the LDI 2a reduces the thickness of the pipe 1 by 1.11 mm.

  FIG. 13 is a diagram for explaining the LDI detection area of the first embodiment.

  According to the graph of FIG. 12, the LDI 2a can be detected when the moving distance of the EMAT 11a is 30 mm or less in the ± θ direction. EMAT11c and 11d show EMAT11a after moving 30 mm in the ± θ direction. When EMAT11c and 11d are used, LDI2a can be detected. On the other hand, if the moving distance of the EMAT 11a exceeds 30 mm in the ± θ direction, the LDI 2a cannot be detected. Therefore, in the experiment of FIG. 11, it can be seen that LDI2 existing in the region R1 of FIG. 13 can be detected. The region R1 is referred to as an LDI detection area.

  When the same ultrasonic optical probe 5 as in the experiment of FIG. 11 is used, there are various types of ultrasonic optical probe 5 (EMAT11) that transmits ultrasonic waves and ultrasonic optical probe 5 (optical fiber sensor 12) that receives ultrasonic waves. Even if the combination is set and the detection of LDI2 is repeated, LDI2 outside the predetermined region cannot be detected. That is, in this case, the LDI cover ratio of each spool of the pipe 1 cannot be made 100%. The LDI coverage is the ratio of the surface area where LDI2 can be detected to the total surface area of each spool.

  FIG. 14 is a diagram for explaining LDI detection according to the first embodiment.

  In the LDI detection of FIG. 14, the ultrasonic optical probe 5 including the wide-area excitation EMAT 11 of FIG. 7A or FIG. 7B is used. Therefore, a resonance signal can be detected between the ultrasonic optical probes 5 separated by 2φ in the axial direction and 180 ° in the circumferential direction.

  FIG. 14 shows an EMAT 11e arranged at an intersection P moved by −φ in the axial direction and + 45 ° in the circumferential direction from the EMAT 11a in FIG. 11, and −φ in the axial direction and −45 ° in the circumferential direction from the EMAT 11a in FIG. EMAT11f arrange | positioned at the intersection P is shown. Therefore, the EMATs 11e and 11f and the optical fiber sensor 12a are separated from each other by two lines L2 in the axial direction and by one line L1 in the circumferential direction. FIG. 14 further shows the LDI 2b existing on a straight line connecting the EMAT 11e and the optical fiber sensor 12a.

  Since the EMATs 11e and 11f are wide-area excitation EMAT11, it is possible to detect a resonance signal between the EMATs 11e and 11f and the optical fiber sensor 12a. Therefore, in the LDI detection of FIG. 14, the region R2 becomes an LDI detection area, and LDI2 existing in the region R2 can be detected. The region R2 is an isosceles triangle having a base of 102 mm and a height of 150 mm (however, this is not a triangle on a plane but a triangle on a curved surface). In the LDI detection of FIG. 14, LDI2a and LDI2b can be detected.

  Therefore, when setting various combinations of the ultrasonic optical probe 5 that transmits ultrasonic waves and the ultrasonic optical probe 5 that receives ultrasonic waves, the pipe inspection system of the present embodiment has two lines L2 in the axial direction. Various combinations of the ultrasonic optical probes 5 separated by one line L1 in the circumferential direction are set. Examples of such combinations include a combination of the ultrasonic optical probe 5 including the EMAT 11e and the ultrasonic optical probe 5 including the optical fiber sensor 12a, and an ultrasonic including the ultrasonic optical probe 5 including the EMAT 11f and the optical fiber sensor 12a. This is a combination with the optical probe 5.

  When the detection of LDI2 is repeated with these combinations, if the LDI detection areas at the time of detection are overlapped, each spool of the pipe 1 can be completely covered with a large number of LDI detection areas congruent with the region R2. This means that LDI2 in the entire area of each spool can be detected, and the LDI cover ratio of each spool reaches 100%. Therefore, according to the present embodiment, the LDI 2 of the pipe 1 can be detected with high accuracy over the entire area of each spool. The LDI cover ratio of each spool is an example of the cover ratio of the thickness measurement of each spool (the ratio of the surface area capable of measuring the wall thickness to the total surface area of each spool).

  Note that the pipe inspection system of the present embodiment may set a combination of the ultrasonic optical probes 5 other than the combination shown in FIG. 14 as long as the LDI cover ratio of each spool reaches 100%. .

  The reference laser light at the time of LDI inspection of each combination is detected by the optical interferometer 22, and the detection result of the reference laser light is provided to the computer 7. The computer 7 calculates the attenuation rate of the ultrasonic wave based on the detection result of the reference laser beam. This attenuation rate is a ratio of the amplitude of the ultrasonic wave calculated from the reference laser beam to the amplitude of the ultrasonic wave generated from the EMAT 11. Based on this attenuation factor, the computer 7 can calculate the distance between the thinning occurrence place (the occurrence place of LDI 2) of the pipe 1 and the ultrasonic probe 5 on the receiving side. Further, the computer 7 may calculate the position of the thinning occurrence location (the occurrence location of LDI 2) of the pipe 1 based on the two attenuation factors calculated from the two combinations.

  FIG. 15 is a diagram for explaining LDI detection according to a modification of the first embodiment.

Figure 15 is simultaneously power the ultrasonic optical probe 5 _{1-5 5} is supplied, the ultrasonic beam probe 5x is, shows how to receive an ultrasonic wave transmitted from the ultrasonic optical probe 5 ₁ to 5 ₅ . Ultrasonic optical probe 5 _{1-5 5} are located in different directions with respect to the ultrasound beam probe 5x. Specifically, the ultrasonic optical probes 5 ₄ and 5 ₅ are positioned in the circumferential direction (± θ direction) of the ultrasonic optical probe 5x. Ultrasonic optical probe 5 ₂ is positioned in the axial direction (-z direction) of the ultrasonic beam probe 5x. The ultrasonic optical probes 5 ₁ and 5 ₃ are located in the spiral direction of the ultrasonic optical probe 5x.

In this modified example, even if ultrasound is weak from the individual ultrasound beam probe 5 ₁ to 5 _5, ultrasonic optical probe 5x can these ultrasonic waves are received strong synthetic ultrasound synthesized . Therefore, according to the present modification, it is possible to improve the accuracy of LDI detection. In this case, 5 ₁ to 5 ₅ ultrasonic beam probe, an example of a plurality of first ultrasound beam probe, the ultrasonic beam probe 5x are examples of one or more second ultrasonic beam probe .

Figure 15 further ultrasonic beam probe 5x the ultrasonic beam probe 5y have shown how the receiving ultrasonic wave transmitted from the ultrasonic optical probe 5 ₁ to 5 _3.

In this modification, the reference laser light from the light source 21 is simultaneously supplied to the ultrasonic optical probes 5x and 5y, and the reference laser light output from the ultrasonic optical probes 5x and 5y is simultaneously detected by the optical interferometer 22. Therefore, according to this modification, it is possible to perform the inspection with the two ultrasonic optical probes 5x and 5y in a short time. Further, according to the present modification, as described later, it is possible to estimate the shape and position of the LDI 2 by detecting the reference laser light from the two ultrasonic optical probes 5x and 5y. In this case, ultrasonic optical probe 5 ₁ to 5 ₃ are examples of one or more first ultrasonic beam probe, the ultrasonic beam probe 5x, 5y, an example of a plurality of second ultrasonic beam probe It is.

  FIG. 15 further shows a state in which the ultrasonic optical probe 5z receives an ultrasonic wave transmitted from the ultrasonic optical probe 5x. LDI2 shown in FIG. 15 is located on a straight line connecting the ultrasonic optical probes 5x and 5z. Since the ultrasonic optical probe 5z is adjacent to the spiral direction of the ultrasonic optical probe 5x, the distance between the ultrasonic optical probes 5x and 5z is longer than the diameter φ (= 150 mm) of the pipe 1. Therefore, if the ultrasonic wave from the ultrasonic optical probe 5x is weak, LDI2 shown in FIG. 15 may not be detected by the ultrasonic optical probe 5z.

Therefore, in this modification, from the ultrasonic optical probe 5 ₁ to 5 ₅ ultrasound phase aligned with the position of the ultrasonic beam probe 5x, amplitude of the combined ultrasonic these ultrasonic waves of the ultrasonic beam probe 5x as it will be enhanced in the position to operate the EMAT11 ultrasonic optical probe ₅ 1 to 5 _5. Further, in the present modification, the phase of the ultrasonic wave from the ultrasonic optical probe 5x is aligned with the position of the ultrasonic wave probe 5x and the ultrasonic wave from the ultrasonic optical probe 5x. The EMAT 11 of the ultrasonic optical probe 5x is operated so as to be enhanced by the above. Therefore, according to this modification, it is possible to propagate strong ultrasonic waves on a straight line connecting the ultrasonic optical probes 5x and 5z, and it is possible to improve the detection accuracy of the LDI2. In addition, according to the present modification, it is possible to detect higher-order modes, and it is possible to improve the reliability of LDI detection.

Note that the positional relationship between the ultrasonic optical probes 5x and 5z may be set to a different positional relationship from the positional relationship in FIG. Further, the combination of the ultrasonic optical probes 5 that supply ultrasonic waves to the ultrasonic optical probes 5x may be other than the ultrasonic optical probes 5 _{1 to} 5 ₅ . In this modification, various positional relationships of the ultrasonic optical probes 5x and 5z and various combinations of the ultrasonic optical probes 5 that supply ultrasonic waves to the ultrasonic optical probe 5x are set. The behavior of the reference laser light when the LDI 2 is on the straight line connecting the acoustic wave probes 5x and 5z may be investigated, and the result of the investigation may be stored in the computer 7 as a database. Thereby, the computer 7 can easily detect LDI2 by collating the detection result of the reference laser light from the ultrasonic optical probe 5z with the database. For example, the database may include data for estimating the shape and position of the LDI 2 as described later.

  FIG. 16 is a cross-sectional view for explaining types of the LDI 2 according to the first embodiment.

  FIG. 16A to FIG. 16C show the LDI 2 generated in the pipe 1. The symbol T1 represents the diameter of LDI2. The diameter T1 of LDI2 is, for example, about 20 to 30 mm. Symbol T2 represents the depth of LDI2. The depth T2 of LDI2 is about 2 mm, for example.

  A symbol K indicates a corner portion between the bottom surface and the side surface of each LDI 2. The corner portion K of the LDI 2 in FIG. 16A has an angle of 90 degrees. The corner portion K of the LDI 2 in FIG. 16B has an angle larger than 90 degrees (for example, 135 degrees). The LDI 2 in FIG. 16C has a corner K where the boundary between the bottom surface and the side surface is ambiguous. As described above, FIGS. 16A to 16C show the LDI 2 in which the shape of the corner portion K is different. Hereinafter, the cross-sectional shapes of the LDI 2 in FIG. 16A to FIG.

  As a result of the experiment, it was found that the LDI2 having a right-angle shape is easily transmitted, the LDI2 having a curved shape is hardly transmitted, and the LDI2 having an obtuse angle shape is further difficult to transmit. That is, the ultrasonic wave permeability with respect to these LDI2 is highest in the right-angled LDI2 and lowest in the obtuse-angled LDI2. However, the corner K of the obtuse LDI2 was set to 135 degrees. Further, as a result of the experiment, it was found that the ultrasonic wave permeability when an ultrasonic wave hits an LDI2 in the axial direction is higher than the ultrasonic wave permeability when an ultrasonic wave hits the LDI2 in the circumferential direction. did.

  Based on the results of these experiments, when the difference in the transmission of ultrasonic waves between the axial direction and the circumferential direction can be ignored, when ultrasonic waves hit the LDI2 having a right angle, a strong transmitted wave and a weak reflected wave are observed. It is thought that it is done. On the other hand, when an ultrasonic wave hits the obtuse-shaped LDI2, it is considered that a transmitted wave having a weak intensity and a reflected wave having a strong intensity are observed.

  Therefore, in the modification of FIG. 15, the computer 7 detects the transmitted wave and the reflected wave in the ultrasonic wave based on the detection result of the reference laser beam. Then, the computer 7 estimates the shape of the LDI 2 based on the ratio between the transmitted wave intensity and the reflected wave intensity. For example, if the ratio of transmitted waves is higher than the first predetermined value, the shape of LDI2 is estimated to be a right-angle shape. Further, if the ratio of the transmitted wave is between the first predetermined value and the second predetermined value, the shape of LDI2 is estimated as a curved shape. If the ratio of transmitted waves is lower than the second predetermined value, the shape of LDI2 is estimated to be an obtuse angle shape.

For example, the ultrasonic wave from the ultrasonic beam probe 5x, the ultrasonic beam probe 5z and ultrasonic optical probe 5 ₄ it is assumed that it receives. In this case, ultrasonic optical probe 5x as shown in FIG. 15, when LDI2 are present on a straight line connecting 5z, reference laser beam affected by the LDI2 is an ultrasonic beam probe 5z and ultrasonic optical probe 5 ₄ Detected. When detecting an ultrasonic wave from the reference laser beam from the ultrasonic optical probe 5z, it is considered that this ultrasonic wave is generally a transmitted wave. On the other hand, when detecting an ultrasonic wave from the reference laser beam from the ultrasonic optical probe 5 _4, the ultrasound is considered to be generally reflected wave. In this case, the ratio of the intensity of the transmitted wave and the reflected wave substantially matches the ratio of the intensity of the former ultrasonic wave and the latter ultrasonic wave. Therefore, the ratio of the intensity of the transmitted wave and the reflected wave can be calculated based on the detection result of these ultrasonic waves, and the shape of the LDI 2 can be estimated based on this ratio.

  However, when the difference in the transmissivity of the ultrasonic waves between the axial direction and the circumferential direction cannot be ignored, the shape of the LDI 2 may not be correctly estimated unless the difference in the transmissivity is taken into consideration. Therefore, in this modification, a table for estimating the shape of LDI2 from the above-described intensity ratio is set in consideration of the difference in transparency, and this table is stored in the computer 7 as a database. Also good. In this case, the shape of LDI 2 can be estimated more accurately by using this table.

Further, the computer 7 can estimate the position of the LDI 2 based on the propagation direction of the transmitted wave and the propagation direction of the reflected wave. For example, when receiving the ultrasonic wave from the ultrasonic beam probe 5x the ultrasonic beam probe 5z and ultrasonic optical probe 5 _4, ultrasonic optical probe 5z can detect the propagation direction of the transmitted wave, ultrasonic sonic optical probe 5 ₄ is capable of detecting the propagation direction of the reflected wave. In this case, the computer 7, extend the straight line along the propagation direction of the transmitted wave from the ultrasonic beam probe 5z, stretched straight along the propagation direction of the reflected waves from the ultrasonic optical probe 5 _4, the intersection of these straight lines By calculating, the position of LDI2 can be estimated. Note that the above database may also be used for estimating the position of LDI2.

  As described above, in the present embodiment, the pipe 1 can be inspected by selecting different ultrasonic probes 5 as the ultrasonic optical probe 5 that transmits ultrasonic waves and the ultrasonic optical probe 5 that receives ultrasonic waves. . Therefore, according to the present embodiment, it is possible to inspect the state of the pipe 1 in a place other than the place where the ultrasonic optical probe 5 is installed.

  Although several embodiments have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. The novel apparatus and methods described herein can be implemented in a variety of other forms. In addition, various omissions, substitutions, and changes can be made to the forms of the apparatus and method described in the present specification without departing from the spirit of the invention. The appended claims and their equivalents are intended to include such forms and modifications as fall within the scope and spirit of the invention.

1: piping, 1a: elbow part, 1b: orifice part,
2: LDI, 3: Plate thickness sensor, 4: FAC,
5: Ultrasonic optical probe, 6: Pipe inspection device, 7: Computer, 8: Heat insulating material,
11: Electromagnetic ultrasonic oscillator, 12: Optical fiber sensor,
13: Resin sheet, 14: Adhesive,
21: Light source, 22: Optical interferometer, 23: Waveform signal generator, 24: Amplifier
25: Electric switch, 26: Optical switch, 27: Mode switch,
31: 1st optical fiber, 32: 2nd optical fiber, 33: Power supply line,
41: optical fiber, 42: circulator, 43: reflection end

Claims (15)

A selection unit for selecting the first and second ultrasonic optical probes from a plurality of ultrasonic optical probes attached to the pipe;
Electric power is supplied to the ultrasonic oscillator of the first ultrasonic optical probe, ultrasonic waves are input from the ultrasonic oscillator to the pipe, and the ultrasonic waves are transmitted to the second ultrasonic wave through the pipe. A power supply for supplying the optical fiber sensor of the optical probe;
A light detection unit for detecting laser light transmitted through the optical fiber sensor of the second ultrasonic optical probe;
Equipped with a,
Each of the ultrasonic optical probes is a pipe inspection apparatus including an optical fiber sensor wound in an elliptical shape . The ultrasonic optical probe is annularly attached to each of the N (N is an integer of 2 or more) ultrasonic optical probes around the pipe, and the elliptical long axis is parallel to the circumferential direction of the pipe. It is attached to the pipe so that the pipe inspection apparatus according to claim 1. A selection unit for selecting the first and second ultrasonic optical probes from a plurality of ultrasonic optical probes attached to the pipe;
Electric power is supplied to the ultrasonic oscillator of the first ultrasonic optical probe, ultrasonic waves are input from the ultrasonic oscillator to the pipe, and the ultrasonic waves are transmitted to the second ultrasonic wave through the pipe. A power supply for supplying the optical fiber sensor of the optical probe;
A light detection unit for detecting laser light transmitted through the optical fiber sensor of the second ultrasonic optical probe;
With
The ultrasonic optical probe is attached to the intersection of a plurality of first lines extending in the first direction on the surface of the pipe and a plurality of second lines extending in the second direction on the surface of the pipe,
The selection unit, as the first and second ultrasonic optical probes, is separated by two second lines in the first direction and separated by one first line in the second direction. Select a combination of ultrasonic optical probes ,
Pipe inspection equipment. The ultrasonic oscillator is
A coil to which the electric power is supplied;
A first magnet having a first pole on the coil side and a second pole on the opposite side of the coil;
A second magnet having a shape surrounding the first magnet, having the second pole on the coil side, and having the first pole on the opposite side of the coil;
The piping inspection device according to any one of claims 1 to 3 . The ultrasonic oscillator is
A coil that is supplied with the electric power and wound in a ring shape;
A cylindrical magnet having a diameter larger than the inner diameter of the ring shape;
The piping inspection device according to any one of claims 1 to 3 . The selection unit sets a plurality of combinations of the first ultrasonic optical probe and the second ultrasonic optical probe, and the combination has a cover ratio for measuring the thickness of each spool of the pipe. The pipe inspection apparatus according to any one of claims 1 to 5 , wherein the pipe inspection apparatus is set to reach 100% by measuring a wall thickness of the pipe. The selection unit selects a first switch for selecting the first ultrasonic optical probe from the plurality of ultrasonic optical probes, and the second ultrasonic optical probe from the plurality of ultrasonic optical probes. and a second switch for selecting, pipe testing apparatus according to any one of claims 1 to 6. The selection unit is input from a first end of the optical fiber sensor, detects a laser beam output from the second end of the optical fiber sensor, and the first mode of the optical fiber sensor. A second mode for detecting the laser light input from the end portion and reflected by the reflecting portion connected to the second end portion of the optical fiber sensor and output from the first end portion of the optical fiber sensor; The pipe inspection apparatus according to any one of claims 1 to 7 , further comprising a mode switch that switches between the two. The selection unit selects a plurality of first ultrasonic optical probes and at least one second ultrasonic optical probe from the plurality of ultrasonic optical probes,
The power supply unit simultaneously supplies power to the ultrasonic oscillators of the plurality of first ultrasonic optical probes, inputs ultrasonic waves from the ultrasonic oscillators to the pipe, and transmits the ultrasonic waves to the pipe. Via the optical fiber sensor of the at least one second ultrasonic optical probe,
The light detection unit detects laser light transmitted through the optical fiber sensor of the at least one second ultrasonic optical probe;
The piping inspection device according to any one of claims 1 to 8 . The selection unit selects at least one first ultrasonic optical probe and a plurality of second ultrasonic optical probes from the plurality of ultrasonic optical probes,
The power supply unit supplies power to an ultrasonic oscillator of the at least one first ultrasonic optical probe, inputs ultrasonic waves from the ultrasonic oscillator to the pipe, and transmits the ultrasonic waves to the pipe. Via the optical fiber sensors of the plurality of second ultrasonic optical probes,
The light detection unit simultaneously detects laser light transmitted through the optical fiber sensors of the plurality of second ultrasonic optical probes;
The piping inspection device according to any one of claims 1 to 9 . A first ultrasonic oscillator is selected from a plurality of ultrasonic oscillators attached to the pipe, and a first one of the plurality of optical fiber sensors attached to the pipe separately from the ultrasonic oscillator is attached. A selection unit for selecting an optical fiber sensor of
Power is supplied to the first ultrasonic oscillator, ultrasonic waves are input from the first ultrasonic oscillator to the pipe, and the ultrasonic wave is input to the first optical fiber sensor via the pipe. A power supply unit to supply;
A light detection unit for detecting laser light transmitted through the first optical fiber sensor;
Equipped with a,
Each of the optical fiber sensors is a pipe inspection device wound in an elliptical shape . The optical fiber sensor is annularly attached to each of N (N is an integer of 2 or more) optical fiber sensors around the pipe, and the elliptical long axis is parallel to the circumferential direction of the pipe. The pipe inspection apparatus according to claim 11, attached to the pipe as described above. A first ultrasonic oscillator is selected from a plurality of ultrasonic oscillators attached to the pipe, and a first one of the plurality of optical fiber sensors attached to the pipe separately from the ultrasonic oscillator is attached. A selection unit for selecting an optical fiber sensor of
Power is supplied to the first ultrasonic oscillator, ultrasonic waves are input from the first ultrasonic oscillator to the pipe, and the ultrasonic wave is input to the first optical fiber sensor via the pipe. A power supply unit to supply;
A light detection unit for detecting laser light transmitted through the first optical fiber sensor;
With
The ultrasonic oscillator and the optical fiber sensor are formed at intersections of a plurality of first lines extending in the first direction on the surface of the pipe and a plurality of second lines extending in the second direction on the surface of the pipe. Attached,
The selection unit, as the first ultrasonic oscillator and the first optical fiber sensor, is separated by two second lines in the first direction and one first in the second direction. Select a combination of ultrasonic oscillator and fiber optic sensor separated by line,
Pipe inspection equipment. Selecting the first and second ultrasonic optical probes from a plurality of ultrasonic optical probes attached to the pipe;
Electric power is supplied to the ultrasonic oscillator of the first ultrasonic optical probe, ultrasonic waves are input from the ultrasonic oscillator to the pipe, and the ultrasonic waves are transmitted to the second ultrasonic wave through the pipe. Supply to the optical fiber sensor of the optical probe,
Detecting the laser beam transmitted through the optical fiber in the sensor of the second ultrasonic beam probe,
Based on the detection result of the laser light, the attenuation rate of the ultrasonic wave is calculated,
Based on the ultrasonic attenuation rate, calculate the distance between the pipe thinning occurrence location and the second ultrasonic optical probe,
Piping inspection method including that. Selecting the first and second ultrasonic optical probes from a plurality of ultrasonic optical probes attached to the pipe;
Electric power is supplied to the ultrasonic oscillator of the first ultrasonic optical probe, ultrasonic waves are input from the ultrasonic oscillator to the pipe, and the ultrasonic waves are transmitted to the second ultrasonic wave through the pipe. Supply to the optical fiber sensor of the optical probe,
Detecting laser light transmitted through the optical fiber sensor of the second ultrasonic optical probe;
Based on the detection result of the laser beam, a transmitted wave and a reflected wave in the ultrasonic wave are detected,
Based on the detection result of the transmitted wave and the reflected wave, the shape or position of the thinning occurrence portion of the pipe is estimated,
Including piping inspection method that.

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