JP4625747B2 - Piping inspection device and piping inspection method - Google Patents

Description

  The present invention relates to a pipe inspection method and apparatus for nondestructively detecting pipe thinning and scratches using ultrasonic waves.

  When a long time elapses in the piping of a power plant or chemical plant, corrosion and erosion from the inner and outer surfaces of the piping cause the piping to deteriorate, and finally reaches the thickness of the piping. If it becomes like this, it will lead to leakage of fluid inside a pipe, such as liquid and steam. For this reason, it is necessary to evaluate the thickness of the pipe by non-destructive means and to take measures such as replacement and repair of the pipe before leakage.

  A typical example of a nondestructive measuring means for evaluating the thickness state of a pipe is an ultrasonic thickness gauge. An ultrasonic thickness gauge generally uses an ultrasonic sensor composed of a piezoelectric element that converts electricity and sound to each other, and excites bulk waves (elastic waves such as longitudinal waves and transverse waves) in a target pipe, thereby This is a device that receives the elastic wave reflected at the point by the same or another ultrasonic sensor and measures the wall thickness of the pipe.

  This ultrasonic thickness meter is based on the principle of converting the reception time of the received wave to the wall thickness, and can measure the wall thickness of the pipe with high accuracy, but the inspection range is the contact range of the sensor with the pipe. Is limited to almost the same level. When the inspection requirement range becomes wide like a long pipe, an increase in the number of measurement points by the ultrasonic thickness gauge is assumed, so there is a drawback that inspection takes a long time.

  Also, inspect pipes with insulation problems, such as pipes wrapped with heat insulation, buried pipes embedded in concrete, etc., or vertical pipes standing upright to high places. It takes a lot of time to prepare and clean up.

As one countermeasure against such a time-consuming problem, a guide wave (elasticity formed by interference of longitudinal and transverse waves traveling in an object having a boundary surface such as a pipe or a plate while reflecting or mode-converting. There is a method for inspecting long-distance sections of piping in a lump using waves. FIG. 12 is an explanatory diagram for explaining the guide wave transmission method described in Patent Document 1.
121 is a pipe to be inspected, 122 is an excitation assembly, and includes a plurality of excitation devices 3A, 3B, and 3C. These excitation devices 3A, 3B, 3C are composed of a plurality of ultrasonic probes arranged in the circumferential direction of the pipe.

  In FIG. 12, a plurality of ultrasonic probes in the excitation device 3 </ b> A are simultaneously driven, and a time delay is applied to drive 3 </ b> B and 3 </ b> C in the same manner. Send a lamb wave in one mode. If there is a thinning or a defect in the middle of the pipe 121, the guide wave is reflected at that position, so that the reflected wave is received by the excitation assemblies 3A, 3B, 3C, and the thickness is reduced from the peak value and reception time of the received wave. Alternatively, the defect size and axial position are measured.

  However, if a plurality of ultrasonic probes are not evenly in contact with the pipe 121, only axisymmetric vibration cannot be transmitted, and noise (pseudo signal) is generated due to the influence of non-axisymmetric vibration. There were drawbacks.

As an improvement measure, one transmitter / receiver group is selected for transmission from a plurality of transmitter / receiver groups, one or more transmitter / receiver groups are selected for reception, and transmission / reception is performed. There is a method of obtaining an operation equivalent to transmitting an axially symmetric guide wave by performing a plurality of times of transmission / reception by changing the combination of the above, correcting the received signal and synthesizing the corrected data. FIG. 13 is a schematic diagram showing the configuration of an ultrasonic flaw detector according to this method, wherein 131 is a pipe to be inspected, 134 is a transceiver group, 135 is a transceiver, 136 is a signal processor, 137 is a display,
Reference numeral 138 denotes a control unit, and 9a and 9b are scratches on the pipe 131.

  However, in this method, since only one transceiver group is always selected for transmission, the guide wave propagates in both directions along the pipe axis. By combining the received signals and canceling the signal from the reverse direction, only the reflected signal from a single direction is extracted, but if there is a large reflection source such as the tube end in the reverse direction, In some cases, it cannot be canceled out and remains as noise (pseudo signal).

Japanese National Patent Publication No. 10-507530 JP 2003-57212 A

  As described in the background art above, in the technology that non-destructively inspects pipes by propagating guide waves to the pipes using a plurality of probes arranged around the pipes, The problem is that noise (pseudo signal) is generated due to non-uniformity of the contact state with the pipe.

  Accordingly, an object of the present invention is to contact each probe with a pipe in a technique for non-destructively inspecting a pipe by propagating a guide wave to the pipe using a plurality of probes arranged around the pipe. It is to reduce noise (pseudo signal) generated due to non-uniformity of the state.

  A pipe inspection apparatus for solving the problems of the present invention includes a first ultrasonic probe annular group having a plurality of first ultrasonic probes arranged in a circumferential direction of a pipe, and the first A second ultrasonic probe having a plurality of second ultrasonic probes arranged in a circumferential direction of the pipe at a position distant from the annular group of ultrasonic probes in the axial direction of the pipe. The first ultrasonic probe is adapted to amplify the amplitude of the guide wave propagating in the direction of the inspection ring group and the inspection region of the pipe and reduce the amplitude of the guide wave propagating in the direction opposite to the direction. Means for relatively shifting an application timing for applying a transmission signal to the transducer and an application timing for applying a transmission signal to the second ultrasonic probe; and the first and second ultrasonic probes. Means for transmitting an electrical reception signal obtained by receiving a reflected wave of the guide wave at a child to a signal processing means, In the pipe inspection apparatus for detecting flaws or thinning of the pipe based on the number, means for transmitting / receiving a guide wave to each of the ultrasonic probes, and the amplitude of the transmission signal obtained by transmitting / receiving individually And a transmission signal correction means for correcting the transmission signal by a transmission / reception amplitude correction coefficient obtained based on the amplitude of the reception signal, and reception signals of the first and second ultrasonic probes by the transmission / reception amplitude correction coefficient. The delay time during which the amplitude is amplified by the synthesis of the reception signals of the first and second ultrasonic probes is at least one of the reception signals of the first and second ultrasonic probes A pipe inspection apparatus comprising a correction means for the received signal applied to the signal and a signal processing means for synthesizing the corrected received signal.

  A pipe inspection method for solving the problems of the present invention includes a first ultrasonic probe annular group having a plurality of first ultrasonic probes arranged in an annular shape, and a plurality of second ultrasonic waves. A second ultrasonic probe ring group having probes arranged in a ring, and arranged around the pipe to be inspected at intervals in the axial direction of the pipe; A guide wave is propagated in the pipe with an increased amplitude in the direction of the inspection region by shifting the application time of the transmission signal between the ultrasonic probe and the second ultrasonic probe, and the anti-inspection region The amplitude of the guide wave in the direction is suppressed, and then the ultrasonic wave based on the guide wave reflected at a flaw or a thinning portion of the pipe is changed to the first ultrasonic probe and the second ultrasonic probe. In the pipe inspection method received by a child, ultrasonic waves are transmitted / received to / from the pipes from the first and second ultrasonic probes. The contact state of the first and second ultrasonic probes to the pipe is measured according to the amplitude of the received signal at the time, and the first and second ultrasonic probes are measured based on the contact state. A transmission / reception amplitude correction coefficient for each of the transducers is calculated, and the transmission amplitudes of the ultrasonic transmission signals from the first and second ultrasonic probes to the pipe are corrected based on the transmission / reception amplitude coefficients, respectively. The amplitude of the signal, the ultrasonic wave according to the amplitude of the transmission signal after the correction is transmitted from the first and second ultrasonic probes to the pipe, and the guide wave is propagated to the pipe, The first ultrasonic probe and all the second ultrasonic probes receive ultrasonic waves based on the reflected waves of the guide wave, and the first and second ultrasonic probes. For the received signal of the tentacle, the amplitude is corrected by the transmission / reception amplitude correction coefficient, and A delay time in which the amplitude is amplified by combining the reception signals of the first and second ultrasonic probes is given to at least one of the reception signals of the first and second ultrasonic probes, and The pipe inspection method is characterized by performing correction and then combining the corrected reception signals.

  The pipe inspection method and apparatus of the present invention can reduce noise (pseudo signal) generated by non-uniformity of the contact state of the probe and bidirectional propagation of the guide wave. There is an advantage that inspection with a good S / N ratio is possible even for a pipe having a structural reflection source such as a weld line.

  One form of the pipe inspection apparatus of the present invention is to solve the problem of non-uniform contact state of the probe and noise (pseudo signal) generated by bidirectional propagation of the guide wave. A first ultrasonic probe annular group in which a plurality of first ultrasonic probes are arranged in the circumferential direction, and a position away from the first ultrasonic probe annular group in the axial direction of the pipe And a first ultrasonic probe annular group in which a plurality of second ultrasonic probes are arranged in the circumferential direction of the pipe, and a first ultrasonic probe annular group selected from the first ultrasonic probe annular group Transmission / reception means for individually transmitting / receiving signals to / from a second ultrasonic probe selected from the ultrasonic probe and the second ultrasonic probe annular group, and the first ultrasonic probe A signal processing means for adding a plurality of signals received by the annular group and the second ultrasonic probe annular group; To have.

  First, the configuration of the apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a block diagram of the overall configuration of a pipe inspection apparatus according to the present embodiment, in which 1 and 2 are ultrasonic probe ring groups, 3 is a guide wave transmitter / receiver, and 4 is A / D conversion. 5 is a computer, 6 is a guide wave, 7 is a pipe, and 8 is a display device.

  The ultrasonic probe annular group 1 includes ultrasonic probes 1a, 1b, 1c, and 1d. The ultrasonic probe 1a is a single ultrasonic probe or a plurality of ultrasonic probes connected in parallel (not shown). The same applies to the ultrasonic probes 1b, 1c, and 1d, but the number of ultrasonic probes is preferably the same as that of the ultrasonic probe 1a. The ultrasonic probe annular group 2 includes ultrasonic probes 2a, 2b, 2c, and 2d. Each of the ultrasonic probes 2a, 2b, 2c, and 2d is a single ultrasonic probe or a plurality of ultrasonic probes connected in parallel as in the ultrasonic probe 1a. The arrangement of the ultrasonic probe annular groups 1 and 2 will be described later.

  The ultrasonic probe constituting the ultrasonic probe 1a and the like generates a guide wave in the pipe 7, and is constituted by, for example, a piezoelectric element, arranged in contact with the pipe 7, and a guide wave transmitter / receiver. 3 is electrically connected through a coaxial cable. The guide wave transmitter / receiver 3 is a means for applying a transmission waveform to the ultrasonic probe 1a or the like to transmit a guide wave, and further amplifying a reception waveform from the ultrasonic probe 1a or the like. It is connected so that digital data can be communicated, and is connected via a coaxial cable so as to send the received waveform to the A / D converter 4. A display device is connected to the computer 5 so that the result of processing by the computer and data before processing can be displayed on the display device.

  The A / D converter 4 has a function of converting an analog signal into a digital signal, and is connected so as to communicate the received waveform of the guide wave output from the guide wave transmitter / receiver 3 to the computer 5 as a digital waveform. As this A / D converter 4, for example, a commercially available external A / D converter or a computer built-in board type is used.

Next, an example of the internal configuration of the guide wave transceiver 3 will be described with reference to FIG. In the figure,
Reference numerals 3a and 3b denote signal generators, which can be composed of synthesizers or arbitrary waveform generators that can arbitrarily set the frequency of the transmission waveform. 3c and 3d are power amplifiers that amplify the transmission signals from them, and 3e and 3f are element switches on the transmission side that determine which ultrasonic probe the transmission signals from the power amplifier are sent to. It is an element switch on the receiving side that determines whether or not to accept a received signal from the ultrasonic probe. Reference numeral 3h denotes a reception amplifier that amplifies the reception signal received from the element switch 3g.

  Next, the arrangement of the ultrasonic probe annular group 1 and the ultrasonic probe annular group 2 will be described with reference to FIG. Figure 3 shows a pipe made of carbon steel (longitudinal sound velocity = 5940 m / s, transverse wave velocity = 3260 m / s), outer diameter 114.3 mm, wall thickness 6 mm (ratio of wall thickness to outer diameter is 0.052). The relationship between the product of frequency and thickness and the speed of sound of the guide wave in the case of is shown.

  In FIG. 3, 41 is a guide wave T (0,1) mode, 42 is a guide wave T (0,2) mode, 43 is a guide wave T (0,3) mode, and 44 is a guide wave T (0,3) mode. It is called a (0,4) mode, and the larger the m number represented by T (0, m), the more complicated the displacement distribution in the plate thickness direction. The use of the T (0,1) mode is desirable because the signal becomes complicated when a plurality of modes coexist.

  Now, assuming that the frequency is 40 kHz, the phase velocity of the T (0,1) mode of the guide wave is 3260 m / s, so the wavelength λ obtained by dividing the phase velocity by the frequency is 81.5 mm. In FIG. 1, the conditions for reducing the amplitude of the guide wave traveling in one direction of the pipe and maximizing the amplitude of the guide wave traveling in the opposite direction are the ultrasonic probes 1a, 1b, 1c, 1d and the ultrasonic wave. The distance between the probes 2a, 2b, 2c, and 2d is (2n + 1) λ / 4 (n = 0, 1, 2,...), And the ultrasonic probe annular group 1 and the ultrasonic probe annular group 2 are used. The same signal may be transmitted with a delay of (2n + 1) τ / 4 (n = 0, 1, 2,..., Τ is a period). For example, when n = 0, the ultrasonic probe annular group 1 and the same signal are transmitted. The distance between the acoustic probe annular groups 2 is about 20.4 mm.

  Here, the operation of the pipe inspection apparatus according to the first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 4, and FIGS. 5 to 9. First, the computer 5 selects an ultrasound probe and acquires reflected wave data (step S101).

Specifically, the guide wave transmitter / receiver 3 receives a control signal transmitted from the computer 5, and the guide wave transmitter / receiver 3 switches the element switch 3e to connect, for example, the power amplifier 3c and the ultrasonic probe 1a. Similarly, the guide wave transceiver 3 switches the element switch 3g and connects the reception amplifier 3h and the ultrasonic probe 1a.

  Next, the guide wave transmitter / receiver 3 amplifies the signal generated by the signal generator 3a by the power amplifier 3c and applies the amplified signal to the ultrasonic probe 1a. The ultrasonic probe 1 a to which the signal is applied generates vibration in the pipe 7, and the guide wave 6 propagates through the pipe 7. If there is a toe 7a or a weld line in the pipe 7, the guide wave 6 is reflected and received again by the ultrasonic probe 1a. The received signal passes through the element switching device 3g and the receiving amplifier 3h, is converted into a digital signal by the A / D converter 4, and is stored as data in the computer 5.

Next, the computer 5 determines whether or not the data has been acquired by all the ultrasonic probes,
If YES, the process proceeds to step S103, and if NO, the process proceeds to step S101 (step S102). By repeating this operation, the computer 5 applies the same reflection to all the ultrasonic probes, that is, the ultrasonic probes 1a, 1b, 1c, and 1d and the ultrasonic probes 2a, 2b, 2c, and 2d. The reception signal from the source (in this case, the toe 7a of the pipe 7) is obtained as digitized reception signal data.

  Next, the computer 5 calculates a transmission / reception amplitude correction coefficient (step S103). Here, the amplitude of the received signal received by each ultrasonic probe is calculated, and based on a certain amplitude (for example, the maximum amplitude of the received signal or the maximum amplitude within the range where the user has set the time gate), The relative amplitude of the received signal of the ultrasonic probe is calculated.

For example, the amplitude A _1a of the received signal when the ultrasonic probe 1a is selected is used as a reference. If the relative amplitude when the ultrasound probe 1b is selected is r _1b , the change in amplitude due to the contact state is affected by both transmission and reception, so the transmission / reception amplitude correction of the ultrasound probe 1b is performed. The coefficient can be calculated as 1 / √r _1b . The computer 5 performs the above calculation for all the ultrasonic probes and stores the data. The reference received signal is not limited to the ultrasound probe 1a.

Next, the computer 5 selects a set of ultrasonic probes and applies a signal corrected with the calculated transmission / reception amplitude correction coefficient to each ultrasonic probe (step S104). Specifically, the guide wave transmitter / receiver 3 receives the control signal sent from the computer 5, and the guide wave transmitter / receiver 3 switches the element switch 3e to connect the power amplifier 3c and the ultrasonic probe 1a. The element switch 3f is switched to connect the power amplifier 3d and the ultrasonic probe 2a adjacent to the ultrasonic probe 1a. Similarly, the element switch 3g is switched to connect the reception amplifier 3h and the ultrasonic probe 1a.

If the received signal when the ultrasonic probe 1a is selected in the operation of step S103 is used as a reference, the ultrasonic probe 2a is applied to the applied signal (amplitude B) to the ultrasonic probe 1a. The signal amplitude applied to is a signal (amplitude B / √r _2a ) multiplied by the transmission / reception amplitude correction coefficient 1 / √r _2a of the ultrasonic probe 2a (FIG. 5). Further, if the distance between the ultrasonic probe annular groups 1 and 2 is a length corresponding to a quarter wavelength, the time delay of the signal applied to the ultrasonic probe 2a is determined by the ultrasonic probe. What is necessary is just to delay 1/4 period with respect to 1a. By doing so, the amplitude of the guide wave traveling rightward in FIG. 1 can be increased in the same phase, and the amplitude of the guide wave traveling leftward can be decreased in the opposite phase. Further, as shown in FIG. 6, the time delay may be advanced by a quarter period by inverting the sign of the signal applied to the ultrasound probe 2a with respect to the signal applied to the ultrasound probe 1a. . The signal application method of FIG. 6 has a relatively low effect of increasing the amplitude of the guide wave traveling to the right as compared to FIG. 5, but the effect of decreasing the amplitude of the guide wave traveling to the left is relatively low. Big.

  Next, the computer 5 obtains a reception signal of the guide wave (step S105). In step S104, the guide wave transmitter / receiver 3 sends a trigger signal to the A / D converter 4 according to the control signal of the computer 5, and the A / D converter 4 receives the trigger signal and receives an analog signal. Has begun to digitize. Since the reception amplifier 3h and the ultrasonic probe 1a are in a connected state, the guide wave signal received by the ultrasonic probe 1a is amplified by the reception amplifier 3h via the element switching device 3g, and A / D converted. It is converted into a digital signal by the device 4. The computer 5 stores the digital signal as received signal data.

Next, the computer 5 determines whether or not data has been acquired for all combinations of ultrasonic probes. If YES, the process proceeds to step S107, and if NO, the process proceeds to step S104 (step S106). FIG. 7 is a table showing combinations of the transmitting ultrasonic probe and the receiving ultrasonic probe. All 32 combinations of this table are implemented, and the process proceeds to step S107. In the present embodiment, the element switching unit 3g is configured so that only one reception ultrasonic probe can be selected at a time. However, the signals of a plurality of reception ultrasonic probes can be selected at a time. If the number of channels of the element switching device 3g and the A / D converter 4 is increased, the inspection can be completed in an earlier time.

Next, the computer 5 combines the received signals (step S107). At this time, the computer 5 stores all 32 combinations of received signals as received signal data. The computer 5 reads the stored reception signal data and corrects the amplitude and time delay of the reception signal data based on the transmission / reception amplitude correction coefficient calculated in step S103. The received signal data correction procedure will be described with reference to FIG. 8 by taking the received signal data of the ultrasonic probe 1b and the ultrasonic probe 2b as an example when transmitting in the combination of the ultrasonic probes 1a and 2a. To do. FIG. 8A shows the received signal data a1b of the ultrasonic probe 1b. Since the transmission / reception amplitude correction coefficient of the ultrasonic probe 1b is 1 / √r _1b , the computer 5 multiplies this coefficient to correct the reception signal data to obtain reception signal data (after amplitude correction) a1b ′. (FIG. 8B). The computer 5, the received signal data a2b of the ultrasonic probe 2b (FIG. 8 (c)), to correct the amplitude by multiplying the reception amplitude correction coefficient 1 / √r _2b of the ultrasonic probe 2b . Furthermore, since the distance between the ultrasound probes 1b and 2b is a length corresponding to a quarter wavelength, the received signal data after correcting the amplitude is delayed by a quarter period. Received signal data (after amplitude and time delay correction) a2b ′ by this processing is the signal of FIG. The computer 5 performs these processes on all stored received signal data. Finally, the computer 5 adds the received signal data after the amplitude / time delay correction to generate composite signal data.

  In the embodiment of the present invention, since each ultrasonic probe annular group is composed of four ultrasonic probes, it is possible to extract a higher-order mode in the circumferential direction of the guide wave. The basic mode T (0, 1) mode will be described. For the sake of simplicity, when the set of ultrasonic probes for transmission is an ultrasonic probe 1x and an ultrasonic probe 2x (x is any one of a, b, c, and d), The received signal data after amplitude correction when the ultrasonic probe is the ultrasonic probe 1y (y is any one of a, b, c, and d) is assumed to be x1y ′. Similarly, reception signal data after amplitude / time delay correction when the reception ultrasonic probe is the ultrasonic probe 2y is x2y ′.

  At this time, the basic mode T (0, 1) is a mode that vibrates symmetrically with respect to the central axis of the pipe, and thus is obtained by adding all received signal data with the same sign. That is, it can be expressed by Equation 1.

{(A1a '+ a1b' + a1c '+ a1d' + a2a '+ a2b' + a2c '
+ A2d ′) + (b1a ′ + b1b ′ + b1c ′ + b1d ′ + b2a ′ + b2b ′ + b2c ′ + b2d ′) + (c1a ′ + c1b ′ + c1c ′ + c1d ′ + c2a ′ + c2b ′ + c2c ′ + d1 + d1 + d1 + d1 + d1 + d1 + d1 + d1 '+ D2a' + d2b '+ d2c' + d2d ')} / 4 Formula 1
There is also a method shown in FIG. 9 for synthesizing the received signals. Unlike FIG. 8, the received signal data of the ultrasound probe _2b is multiplied by the transmission / reception amplitude correction coefficient 1 / √r _2b to correct the amplitude, and the received signal data after correcting the amplitude is divided into 4 minutes. Advance one cycle. Received signal data (after amplitude / time delay correction) a2b ′ by this processing is the signal of FIG. The basic mode T (0, 1) at this time can be expressed by Equation 2.

{(A1a '+ a1b' + a1c '+ a1d'-a2a'-a2b'-a2c'
-A2d ') + (b1a' + b1b '+ b1c' + b1d'-b2a'-b2b'-b2c'-b2d ') + (c1a' + c1b '+ c1c' + c1d'-c2a'-c2b'-c2c'-c2d ') + (D1a '+ d1b' + d1c '+ d1d'-d2a'-d2b'-d2c'-d2d')} / 4 Formula 2
In the above description, the reception signal data received by the second ultrasonic probes 2a, 2b, 2c, and 2d is time-delayed, but the first ultrasonic probe 1a is used. , 1b, 1c, 1d, the same effect can be obtained by applying a reverse time delay to the received signal data.

  The effect in Example 1 of this invention is demonstrated using FIG. 10 and FIG. FIG. 10 shows a test system. As a test body, a pipe having an outer diameter of 60.5 mm and a wall thickness of 5.5 mm and three mortar-shaped simulated thinnings processed at 500 mm pitch from the end of the pipe was used. Each of the simulated thinnings T1, T2, T3 has a ratio of 1% to the cross-sectional area of the pipe 7, but the maximum depth and the surface opening width (in the pipe axis direction) are as shown in the table of FIG. . Attach the ultrasonic probe ring groups 1 and 2 to the opposite side of the side where the simulated thinning T1, T2 and T3 were processed, and head toward the direction of thinning (right side of the figure). In Example 1 of the invention, a guide wave was transmitted and received, and data of a received signal was obtained. The received signal data is processed and synthesized by the computer 5 and output to the display device 8 as a synthesized signal to display the waveform of the synthesized signal.

  FIG. 11 shows the waveform of the synthesized signal obtained by Example 1 of the present invention in comparison with the waveform of the synthesized signal according to the prior art. (A) is the waveform of the conventional received signal, (b) is the waveform of the synthesized signal obtained by Example 1 of this invention. In either case, the reflected signals from simulated thinning T1, T2, T3 are obtained, but the synthesized signal obtained by the embodiment of the present invention has reduced noise compared to the synthesized signal by the prior art. As a result, the SN ratio was improved.

  As described above, in the present invention, the non-uniformity of the contact state of the probe is corrected by adjusting the transmission / reception amplitude, and the ultrasonic probe adjacent in the axial direction of the pipe is transmitted with a delay to guide. Since the wave is propagated in a single direction, noise (pseudo signal) generated by bidirectional propagation of the guide wave can be reduced, and pipe thinning and flaws can be detected with a high SN ratio.

  The present invention is applied to an ultrasonic flaw detector that inspects a pipe nondestructively using ultrasonic waves.

1 is a block diagram of a pipe inspection device according to a first embodiment of the present invention. It is a figure explaining the structural example of a guide wave transmitter / receiver. It is explanatory drawing which shows the dispersion curve of the phase velocity of a T mode guide wave. It is a flowchart which shows operation | movement of the piping inspection apparatus in Example 1 of this invention. It is a figure explaining the applied signal which correct | amends an amplitude and transmits. It is a figure explaining the applied signal which correct | amends an amplitude and transmits. It is a figure explaining the combination of selection of an ultrasonic probe. It is a figure explaining the process which correct | amends the amplitude of received signal data, and gives a time delay. It is a figure explaining the process which correct | amends the amplitude of received signal data, and gives a time delay. It is the figure which showed the system of the test in the Example of this invention. It is the signal waveform diagram showing the waveform of the synthetic signal in the Example of this invention, and the waveform of the synthetic signal by a prior art example. It is explanatory drawing regarding the conventional guide wave inspection apparatus. It is explanatory drawing regarding the conventional guide wave inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Ultrasonic probe annular group, 1a, 1b, 1c, 1d, 2a, 2b, 2c, 2d ... Ultrasonic probe, 3 ... Guide wave transmitter / receiver, 4 ... A / D converter, 5 ... computer, 6 ... guide wave, 7 ... piping, 8 ... display device.

Claims (4)

A first ultrasonic probe annular group having a plurality of first ultrasonic probes arranged in the circumferential direction of the pipe;
A second ultrasonic probe having a plurality of second ultrasonic probes arranged in a circumferential direction of the pipe at a position away from the first annular group of ultrasonic probes in the axial direction of the pipe; An ultrasonic probe ring group,
A transmission signal is sent to the first ultrasonic probe so as to amplify the amplitude of the guide wave propagating in the direction of the inspection region of the pipe and reduce the amplitude of the guide wave propagating in the direction opposite to the direction. Means for relatively shifting an application time to be applied and an application time to apply a transmission signal to the second ultrasonic probe; and the first and second ultrasonic probes Means for transmitting an electrical reception signal obtained by receiving the reflected wave to the signal processing means,
In a pipe inspection device that detects a flaw or thinning of the pipe based on the received signal,
Means for transmitting and receiving guide waves individually to each of the ultrasonic probes;
Transmission signal correction means for correcting the transmission signal by a transmission / reception amplitude correction coefficient obtained based on the amplitude of the transmission signal and the reception signal obtained by individually transmitting and receiving;
A delay in which the amplitude of the reception signals of the first and second ultrasonic probes is amplified by the transmission / reception amplitude correction coefficient, and the amplitude is amplified by the combination of the reception signals of the first and second ultrasonic probes A received signal correcting means for giving time to at least one of the received signals of the first and second ultrasonic probes;
A pipe inspection device comprising signal processing means for synthesizing the received signal after correction.   The transmission voltage having a value corrected based on the transmission / reception amplitude correction coefficient is generated for each of the first ultrasonic probe and the second ultrasonic probe according to claim 1. A pipe inspection apparatus comprising means for generating a transmission signal to be applied to each of the one ultrasonic probe and the second ultrasonic probe.   3. The transmission / reception amplitude correction coefficient according to claim 2, wherein the transmission / reception amplitude correction coefficient is calculated based on a reception signal generated by the first ultrasonic probe and the second ultrasonic probe receiving an ultrasonic wave. A pipe inspection apparatus comprising a calculation means for calculating the value of the transmission voltage based on a coefficient. A first ultrasonic probe annular group having a plurality of first ultrasonic probes arranged in an annular shape, and a second ultrasonic element having a plurality of second ultrasonic probes arranged in an annular shape An acoustic probe annular group is arranged around the pipe to be inspected at intervals in the axial direction of the pipe,
Next, the amplitude of the guide wave in the pipe is increased in the direction of the inspection region by shifting the timing of applying the transmission signal to the first ultrasonic probe and the second ultrasonic probe. To suppress the amplitude of the guide wave toward the anti-inspection area,
Next, in a pipe inspection method for receiving ultrasonic waves based on the guide wave reflected at a pipe flaw or a thinned portion with the first ultrasonic probe and the second ultrasonic probe,
The ultrasonic waves are transmitted / received to / from the pipes from the first and second ultrasonic probes, and the pipes of the first and second ultrasonic probes are changed depending on the amplitude of the received signal at that time. Measure the contact state to
Based on the contact state, a transmission / reception amplitude correction coefficient for each of the first and second ultrasonic probes is calculated,
The amplitude of the transmission signal of the ultrasonic wave from each of the first and second ultrasonic probes to the pipe is the amplitude of the transmission signal corrected based on the transmission / reception amplitude coefficient,
Transmitting the ultrasonic wave by the amplitude of the transmission signal after the correction from the first and second ultrasonic probes to the pipe and propagating the guide wave to the pipe;
Next, all the first ultrasonic probes and all the second ultrasonic probes receive ultrasonic waves based on the reflected wave of the guide wave,
For the received signals of the first and second ultrasonic probes, the amplitude is corrected by the transmission / reception amplitude correction coefficient, and the amplitude is obtained by combining the received signals of the first and second ultrasonic probes. Applying a delay time to be amplified to at least one of the reception signals of the first and second ultrasonic probes to correct the reception signal,
Next, a pipe inspection method characterized by combining the received signals subjected to correction.

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