JP5158644B2 - Eddy current flaw detection system - Google Patents

Description

  The present invention relates to an eddy current flaw detection system.

  An eddy current test (Remote Field-Eddy Current Testing: RF-ECT) using an indirect magnetic field is used for defect inspection of a ferromagnetic steam generator heat transfer tube.

  The feature of RF-ECT is that it can detect the inner surface and outer surface of a ferromagnetic tube such as a heat transfer tube at the same time, but from the acquired detection signal, is it an inner surface defect (scratch) or an outer surface defect (scratch)? Cannot be identified. Therefore, when RF-ECT is applied to flaw detection (inspection) of a ferromagnetic tube, a direct magnetic field that cannot flaw the outer surface due to the skin effect, that is, can flaw (inspect) only the flaw on the inner surface. In combination with eddy current testing (ECT) using ED, it is discriminated whether it is an internal or external scratch by making a logical judgment with reference to the RF-ECT inspection result and the ECT inspection result. I am doing so. A structure such as a support for supporting the pipe exists on the outer surface, but if the inner surface or the outer surface can be identified, it can be separated from the detection signal.

  FIG. 1 shows an outline of an indirect magnetic field and a direct magnetic field in eddy current flaw detection. Magnetic flux (electromagnetic energy) generated by inserting the exciting coil 2 into the ferromagnetic tube 1 and supplying an alternating current is generated by the magnetic flux 3 flowing in the inner surface region of the tube 1 very close to the exciting coil 2. Forms a flow path (direct magnetic field) and a flow path (indirect magnetic field) of magnetic flux 4 that flows through the tube 1 and flows along the outside of the tube 1 and then flows into the tube 1 at a position far from the exciting coil 1 To do.

  ECT is a flaw detection method in which the detection coil that also serves as the exciting coil 2 detects that the flow of eddy current generated in the tube 1 by the magnetic flux 3 is disturbed by the flaw. This is a flaw detection method in which the detection coil 6 detects that the flow of eddy current generated inside is disturbed by the flaw 5.

  While ECT specializes in the inspection of the inner surface of the tube 1, it has a feature that the inner surface defect detection performance is higher than that of RF-ECT.

  From such a background, an inspection probe for flaw detection of a ferromagnetic tube is configured such that RF-ECT and ECT are arranged coaxially in the axial direction.

  FIG. 2 is a vertical side view of an inspection probe in which RF-ECT and ECT are arranged coaxially in the axial direction.

  The inspection probe 8 for RF-ECT includes a detection coil 81 configured by arranging two coils 811 and 812 in close proximity to each other in the axial direction, and two excitations installed at positions away from the detection coil 81. The coil 82 and 83 are provided.

The inspection probe 9 for ECT has a configuration including an excitation and detection coil (hereinafter referred to as an excitation / detection coil) 91 in which two coils 911 and 912 are arranged close to each other in the axial direction.

  When the RF-ECT and ECT inspection probes 8 and 9 are arranged on the same axis in the axial direction in this way, each detection location (the position of the detection coil 81 and the excitation / detection coil 91) is for two inspections. Since the probes 8 and 9 are separated from each other in the axial direction by the arrangement interval (distance), there is a drawback that it is impossible to simultaneously detect the same place. For this reason, when performing defect evaluation, the amount of axial displacement of the flaw detection waveform is artificially corrected by signal processing, but the movement and speed of the detection coil 81 and the excitation / detection coil 91 when passing are delicate. However, it is extremely difficult to detect flaws in the same place under the same conditions.

  In ECT, in recent years, an inspection probe has been developed to improve the defect detection performance of non-magnetic heat transfer tubes by making the coils 911 and 912 of the excitation / detection coil 91 multi-coiled, and its high detection performance has been evaluated. Has been widely used. Although the inspection probe with the multi-coil excitation / detection coil is effective in this way, the outer surface cannot be inspected due to the skin effect in the case of a ferromagnetic heat transfer tube. Since the RF-ECT inspection probe is provided side by side in the axial direction, the same problem occurs.

  FIG. 3 is a longitudinal front view and a longitudinal side view showing the multi-coil type (a) of the excitation / detection coil 91 in ECT in comparison with the bobbin coil type (b).

As shown in (a), the multi-coil type excitation / detection coil 91 has a plurality of coils 911a (912a), 911b (912b), 911c (912c)... 911n (912n) centered on an axis. a configuration to form a coil group 9 11,912 of two rows arranged in two rows, the exciting / detecting coil 91 of the bobbin coil type, configuration formed by juxtaposing two coils 911 and 912 in the axial direction It is.

JP 2004-294341 A JP 2000-65801 A JP-A-10-197499

  One object of the present invention is to realize a new eddy current flaw detection system capable of improving the defect detection performance. Specifically, the RF-ECT flaw detection and the ECT flaw detection are simultaneously performed on the same place to realize accurate flaw detection.

  Another object of the present invention is to realize a new eddy current flaw detection system capable of improving defect detection performance with a relatively simple configuration. Specifically, RF-ECT flaw detection and ECT flaw detection performed simultaneously on the same location can be performed by using one detection coil used in the RF-ECT flaw detection system as an excitation / detection coil in the ECT flaw detection system. There is in doing so.

  Another object of the present invention is to realize a new eddy current flaw detection system capable of improving the defect detection resolution in the circumferential direction of the tube. More specifically, this is realized by using a detection coil (excitation / detection coil) made into a multi-coil.

  Another object of the present invention is to realize an eddy current flaw detection system using a detection coil (excitation / detection coil) made into a multi-coil with a relatively simple configuration. Specifically, the signal processing system is not required to increase to the number of channels corresponding to the number of multicoils.

  The eddy current flaw detection system of the present invention is an eddy current flaw detection system that performs flaw detection by simultaneously performing RF-ECT and ECT on the same place, and the detection coil in the inspection probe for RF-ECT is used as the inspection probe for ECT. This is realized by being configured to be used (combined) as an excitation / detection coil.

  In addition, the detection coil in the RF-ECT inspection probe of the present invention is configured as a multi-coil type, thereby realizing improved defect detection performance (circumferential resolution).

Specifically, an RF-ECT flaw detection system in which an excitation coil of an inspection probe is connected to an excitation output terminal of an RF-ECT signal processing system and a detection coil is connected to a detection input terminal, and an excitation / detection coil of the inspection probe In an eddy current flaw detection system having an ECT flaw detection system in which an ECT signal processing system is connected to an excitation output terminal and a detection input terminal,
The ECT flaw detection system connects the detection coil of the RF-ECT flaw detection system to the detection terminal of the ECT flaw detection system by using the excitation / detection coil also as the detection coil in the RF-ECT flaw detection system and a resistor. And connected to the excitation output terminal of the ECT flaw detection system .

  The resistance value of the resistor is set to be larger than the value of the internal resistance between the excitation output terminals in the ECT flaw detection system.

Further, the detecting coil is characterized in that by a plurality of coils around the axis a structure of forming the coil groups 2 rows arranged in two rows in a ring.

  Then, the detection input terminal for one channel of the RF-ECT signal processing system and the detection input terminal for one channel of the ECT signal processing system are selectively connected to a plurality of coils in the detection coil to sequentially input the detection signals. A distributor is provided.

  According to the present invention, it is possible to improve the defect detection performance by configuring so as to realize accurate flaw detection by simultaneously performing RF-ECT flaw detection and ECT flaw detection on the same place.

  In the present invention, RF-ECT flaw detection and ECT flaw detection performed simultaneously on the same place are performed by using one detection coil used in the RF-ECT flaw detection system as an excitation / detection coil in the ECT flaw detection system. By configuring, it is possible to improve the defect detection performance with a relatively simple configuration.

  Further, according to the present invention, the defect detection in the circumferential direction of the pipe is realized by configuring the multi-coil type detection coil (excitation / detection coil) that is used in both RF-ECT flaw detection and ECT flaw detection performed simultaneously on the same place. The resolution can be improved.

  In the present invention, the detection signal from the detection coil (excitation / detection coil) made into a multi-coil is configured to be selectively input to the detection input terminal by the distributor, so that the signal processing system is relatively simple. Can be realized with a simple configuration.

The present invention includes an RF-ECT flaw detection system in which an excitation coil of an inspection probe is connected to an excitation output terminal of an RF-ECT signal processing system and a detection coil is connected to a detection input terminal, and an excitation / detection coil of the inspection probe. In an eddy current flaw detection system having an ECT flaw detection system connected to an excitation output terminal and a detection input terminal of an ECT signal processing system,
In the ECT flaw detection system, the excitation / detection coil is also used as the detection coil in the RF-ECT flaw detection system, and the detection coil of the RF-ECT flaw detection system is connected to the detection input terminal of the ECT flaw detection system. Connected to the excitation output terminal of the ECT flaw detection system via a detector,
The resistance value of the resistor is set larger than the value of the internal resistance between the excitation output terminals in the ECT flaw detection system,
The RF-ECT flaw system of detection coils, a configuration in which it was a plurality of coils around the axis are arranged in two rows in a ring to form a coil group of two rows,
A distributor is provided that selectively connects one channel detection input terminal of the RF-ECT signal processing system and one channel detection input terminal of the ECT signal processing system to a plurality of coils in the detection coil.

  The eddy current flaw detection system in this embodiment is a system that doubles as a detection coil in an inspection probe and performs flaw detection by simultaneously performing RF-ECT and ECT on the same place.

  Furthermore, the detection coil (excitation / detection coil) is configured as a multi-coil type, the resolution in the circumferential direction is improved, and eddy current flaw detection capable of performing flaw detection on the inner and outer surfaces of a ferromagnetic tube is performed at high performance. The system is realized.

  This eddy current flaw detection system is realized by a simple method of slightly changing a conventional eddy current flaw detection system. Specifically, the eddy current flaw detection system is used as a detection coil in a conventional inspection probe for RF-ECT. The two coils function as excitation / detection coils in the ECT inspection probe.

  FIG. 4 is a vertical side view of a multi-coil type RF-ECT and ECT inspection probe.

  In FIG. 4, an inspection probe 10 includes an excitation / detection coil 101 in which two rows of multi-coil type coil groups 1011 and 1012 are arranged close to each other in the axial direction, and both sides of the excitation / detection coil 101 in the axial direction. Are provided with two exciting coils 102 and 103 installed at positions separated by a predetermined distance. Two rows of coil groups 1011 and 1012 of the excitation / detection coil 101 function as a detection coil in RF-ECT and an excitation / detection coil in ECT.

  FIG. 5 is a functional block diagram of an eddy current flaw detection system using a bobbin coil type inspection probe. The bobbin coil type inspection probe has a configuration in which the excitation / detection coil 101 in the aforementioned multi-coil type RF-ECT and ECT inspection probes is changed to a bobbin coil type (see FIG. 3B).

  In FIG. 5, the inspection probe 10 connects the excitation coils 102 and 103 to the excitation output terminal 111 of the RF-ECT signal processing system 11 via the shielded core wire 15a and the shield 15b, and the bobbin type excitation / detection coil. The coils 1011 and 1012 of the shield 101 are connected to the detection input terminal 112 of the RF-ECT signal processing system 11 through the shield wire cores 16a and 16b, the core wires 17a and the shield 17b, and the shield wire core wire 18a and the resistor. 13 is connected to the excitation output terminal 121 of the ECT signal processing system 12 through the series circuit of the shield 18b and the core wire 19a and the resistor 14 and the shield 19b, and the shield wire core wire 20a and the shield 20b and the core wire 21a and the shield. Connected to the detection input terminal 122 of the ECT signal processing system 12 via 21b

  The resistors 13 and 14 connected in series to the excitation current supply system from the excitation output terminal 121 of the ECT signal processing system 12 to the coils 1011 and 1012 of the excitation / detection coil 101 are made to be resistors having the same resistance value. The detection signals induced in the coils 1011 and 1012 can be effectively input to the detection signal processing system. The resistance values of the resistors 13 and 14 to be connected are detected in consideration of the relationship between the protection resistance in the excitation current supply system (excitation output terminal 121) in the ECT signal processing system 12 and the impedance of the excitation / detection coil 101. Select so that the detection signal effectively flows into the signal input system.

  The resistors 13 and 14 can be specialized for flaw detection on the inner surface or the outer surface by changing their values. When the resistance value is decreased, the detection performance of the inner surface (ECT flaw detection) is increased, and when the resistance value is increased, the detectability of the outer surface (RF-ECT flaw detection) is increased.

  The RF-ECT signal processing system 11 outputs an excitation current of about several hundred Hz from the excitation output terminal 111 and supplies the excitation current to the excitation coils 102 and 103, and the indirect magnetic field (the tube 1 of the tube 1) generated by the excitation coils 102 and 103. Detection signal induced in the coils 1011 and 1012 of the excitation / detection coil 101 by the eddy current disturbed by the scratch) is input from the detection input terminal 112, and after processing such as phase detection, the presence or absence of a defect (scratch) The flaw detection is performed.

  The ECT signal processing system 12 outputs an excitation current of about several tens of kHz to several hundreds of kHz from the excitation output terminal 121 and supplies it to the coils 1011 and 1012 of the excitation / detection coil 101 via the resistors 13 and 14. A detection signal induced in the coils 1011 and 1012 by the direct magnetic field generated by the coils 1011 and 1012 (the magnetic field due to the eddy current disturbed by the flaw of the tube 1) is input from the detection input terminal 122, and processing such as phase detection is performed. Function to detect flaws (defects). That is, the presence / absence of a flaw is determined (flaw detection) based on a signal due to the disturbance of the magnetic field.

  FIG. 6 is a diagram showing the flow of excitation current (excitation magnetic flux) and detection signal in the flaw detection.

  For flaw detection, the inspection probe 10 is inserted into the tube 1 to be flaw detected.

  The RF-ECT signal processing system 11 outputs an excitation current of about several hundred Hz from the excitation output terminal 111 and supplies the excitation current to the excitation coils 102 and 103. The excitation coils 102 and 103 allow the AC indirect magnetic field (RF- ECT excitation magnetic flux) is generated. Eddy currents generated in the tube 1 due to the electromagnetic induction effect by the indirect magnetic field flow to the surface of the tube 1 due to the skin effect, and are disturbed by scratches formed on the surface of the tube 1. An RF-ECT detection signal (current) generated by a voltage induced in the coils 1011 and 1012 of the excitation / detection coil 101 by a magnetic flux generated by the eddy current including the disturbance is input from the detection input terminal 112, and this detection signal The amount of disturbance (disturbance of eddy current due to scratches) is determined.

  The ECT signal processing system 12 outputs an ECT excitation current of about several tens of kHz to several hundreds of kHz from the excitation output terminal 121 and supplies it to the coils 1011 and 1012 of the excitation / detection coil 101 via the resistors 13 and 14. Then, an alternating direct magnetic field is generated by the coils 1011 and 1012. The eddy current generated in the tube 1 by the electromagnetic induction effect by the direct magnetic field is disturbed by the scratch formed on the inner surface of the tube 1. Then, an ECT detection signal (current) generated by a voltage induced in the coils 1011 and 1012 by the magnetic flux generated by the eddy current including the turbulence is input from the detection input terminal 122, and this detection signal turbulence (eddy current due to scratches) is input. The amount of disturbance).

  When there is no scratch or the like in the tube 1, this eddy current is not disturbed, but when there is a scratch or the like, the eddy current is disturbed.

  When the resistors 13 and 14 are not present in the ECT excitation current supply system, the excitation output terminal 121 having a low internal resistance of the ECT signal processing system 12 is detected by the voltage induced in the coils 1011 and 1012 of the excitation / detection coil 101. And the normal flaw detection function is lost because the flow does not flow into the detection input terminals 112 and 122 (inter-terminal internal resistances 112a, 112b, 122a, and 122b) in the signal processing systems 11 and 12, respectively. The presence of vessels 13 and 14 is important.

  By setting the resistance values of the resistors 13 and 14 to be larger than the internal resistance between the excitation output terminals 121 of the ECT signal processing system 12, the detection signal flows into the detection input terminals 112 and 122 of the signal processing systems 11 and 12. Can be normalized. When the resistance value is small, the ECT excitation current easily flows, so that the inner surface detectability by ECT flaw detection is improved. When the resistance value is increased, the ECT excitation current is suppressed, so that the influence of the ECT flaw detection system can be suppressed for the RF-ECT flaw detection system, and the detectability of the outer surface is improved.

  FIG. 7 is a functional block diagram of the eddy current flaw detection system in this embodiment.

  The inspection probe 10 incorporates the above-described RF-ECT signal processing system 11 and ECT signal processing system 12 in the detection signal acquisition unit 22. An excitation signal oscillator 2201, a phase shifter 2202, a bridge circuit 2203, an amplification circuit 2204, a phase detection circuit 2205, a filter 2206, and an X / Y processing circuit 2207 are processing circuits of the RF-ECT signal processing system 11 similar to the conventional system. The excitation signal oscillator 2208, the phase shifter 2209, the bridge circuit 2210, the amplification circuit 2211, the phase detection circuit 2212, the filter 2213, and the X and Y processing circuit 2214 are processing circuits of the ECT signal processing system 12 similar to the conventional system.

  In the RF-ECT signal processing system 11, the oscillation output of the excitation signal oscillator 2201 is distributed to the RF-ECT excitation coils 102 and 103 and the phase shifter 2202. The excitation signal distributed to the RF-ECT excitation coils 102 and 103 side causes an excitation current to flow through the RF-ECT excitation coils 102 and 103 to generate an indirect magnetic field.

  The phase shifter 2202 shifts the input excitation signal to generate a reference signal for phase detection.

  The bridge circuit 2203 is composed of coils 1011 and 1012 in the excitation / detection coil 101 and a variable resistor, and is adjusted so that a balance can be obtained in the sound portion of the flaw detection target tube (test body) 1 by changing the variable resistor. Thus, the bridge is unbalanced at a place where the tube 1 is damaged, and a voltage (detection signal) corresponding to the impedance change of the coils 1011 and 1012 is obtained. Since this detection signal (voltage) is very small, it is amplified by the amplifier circuit 2204.

  The phase detection circuit 2205 compares the phase of the output signal of the phase shifter 2202 and the output signal of the amplification circuit 2204 and outputs it as a detection signal. The filter 2206 extracts only the detection signal component based on the RF-ECT excitation magnetic flux. , Y circuit 2207 processes the phase shift of the detection signal and outputs it as an X, Y signal.

  In the ECT signal processing system 12, the oscillation output of the excitation signal oscillator 2208 is distributed to the coils 1011 and 1012 and the phase shifter 2209 in the excitation / detection coil 101.

  The excitation signals distributed to the coils 1011 and 1012 side cause an excitation current to flow through the coils 1011 and 1012 to directly generate a magnetic field.

  The phase shifter 2208 shifts the input excitation signal to generate a reference signal for phase detection.

  The bridge circuit 2210 is composed of the coils 1011 and 1012 in the excitation / detection coil 101 and a variable resistor, and is adjusted so that a balance can be obtained in the sound portion of the flaw detection target tube (test body) 1 by changing the variable resistor. Thus, the bridge is unbalanced at a place where the tube 1 is damaged, and a voltage (detection signal) corresponding to the impedance change of the coils 1011 and 1012 is obtained. Since this detection signal (voltage) is very small, it is amplified by the amplifier circuit 2211.

  The phase detection circuit 2212 compares the phase of the output signal of the phase shifter 2209 and the output signal of the amplification circuit 2211 and outputs it as a detection signal. The filter 2213 extracts only the detection signal component based on the ECT excitation magnetic flux. The circuit 2214 processes the phase shift of the detection signal and outputs it as X and Y signals.

  The recording unit 23 stores and holds the X and Y signals of the RF-ECT signal processing system and the ECT signal processing system output from the detection signal acquisition unit 22 as in the conventional system.

  The evaluation unit 24 reads the ECT signal processing system and the X and Y signals of the ECT signal processing system stored in the recording unit 23, smoothes them by the smoothing processing unit 2401, and performs evaluation processing by the evaluation processing unit 2402. The evaluation unit 24 has a configuration in which the misalignment correction processing unit in the evaluation unit in the conventional system is omitted.

  Then, as in the conventional system, the determination processing unit 25 logically determines the evaluation result to determine whether the tube 1 is a surface flaw or an inner surface flaw (a flaw is detected in both the RF-ECT flaw detection system and the ECT flaw detection system). If the flaw is detected only in the ECT flaw detection system, it is a flaw on the outer surface.

  According to such an eddy current flaw detection system, the RF-ECT flaw detection system and the ECT flaw detection system perform flaw detection inspections at the same place with one excitation / detection coil 101, and therefore, no correction process for positional deviation is necessary. Accurate flaw detection in the same place can be realized.

  FIG. 8 shows the waveform of the detection signal. The X, Y (90 ° phase lag) signal output from the detection signal acquisition unit 22 is a noise signal when the inspection probe 10 is transported to X, and a noise signal with a reduced noise in Y. In order to facilitate identification, the X and Y phases are adjusted.

  In FIG. 8, the left side is the conventional method and the right side is the method of this embodiment, the upper side is the result of the RF-ECT flaw detection, and the lower side is the result of the ECT flaw detection. In the conventional method, since the distance between the detection coils is about 300 mm away, it is necessary to perform a distance correction process and make a pseudo match, but in the embodiment method, the same detection coil (excitation / detection coil 101) is used. Since the time difference between the RF-ECT flaw detection system and the ECT flaw detection system does not occur, correction processing is unnecessary.

  FIG. 9 shows the relationship between the resistance values of the resistors 13 and 14 connected in series to the ECT exciting current supply system and the detection characteristics.

  When the resistance values of the resistors 13 and 14 are changed, the detectability of flaws (defects) can be specialized (changed) on the inner surface or the outer surface. The change in resistance value controls the value of current flowing through each coil 1011, 1012.

  The detection result shown in FIG. 8 is obtained by performing a flaw detection with a resistance value in which the characteristics of the ECT flaw detection system and the RF-ECT flaw detection system intersect (good balance).

  FIG. 10 shows a flaw detection comparison result (Y signal) in flaw detection using a multi-coil type inspection probe and a bobbin coil type inspection probe. If the inspection probe is made into a multi-coil, it is possible to detect a local notch in the outer circumferential direction (width 0.3 mm, length 10 mm, depth 20% with respect to the tube thickness).

  FIG. 11 is a functional block diagram of an eddy current flaw detection system using the multi-coil type inspection probe 10. The eddy current flaw detection system using the multi-coil type inspection probe 10 can improve the defect detection resolution in the circumferential direction of the tube.

  The RF-ECT signal processing system 11 is configured to supply an excitation current to the excitation coils 102 and 103 as in the above-described embodiment, but the detection signal input terminal 112 for inputting the detection signal is provided in the excitation / detection coil 101. N-channel input terminals corresponding to the coils 1011a to 1011 and 1012a to n are provided, and a signal processing system having a corresponding number of channels is provided therein.

  The ECT signal processing system 12 supplies an excitation current in parallel to the coils 1011a to n and 1012a to n in the excitation / detection coil 101 via the resistors 13 and 14, and a detection signal input terminal 122 for inputting a detection signal includes: The excitation / detection coil 101 includes n-channel input terminals corresponding to the coils 1011a to n and 1012a to n, and internally includes a signal processing system having a corresponding number of channels.

  Then, the RF-ECT signal processing system 11 and the ECT signal processing system 12 execute signal processing in the same manner as in the above-described embodiment, and the detection result is processed by the recording unit 23, the evaluation unit 24, and the determination processing unit 25. Execute.

  FIG. 12 is a diagram showing the flow of excitation current (excitation magnetic flux) and detection signal during flaw detection in this embodiment.

  For flaw detection, the inspection probe 10 is inserted into the flaw detection target tube 1 in the same manner as in the above-described embodiment.

  The RF-ECT signal processing system 11 outputs an excitation current of about several hundred Hz from the excitation output terminal 111 and supplies the excitation current to the excitation coils 102 and 103. The excitation coils 102 and 103 allow the AC indirect magnetic field (RF- ECT excitation magnetic flux) is generated. Eddy currents generated in the tube 1 due to the electromagnetic induction effect by the indirect magnetic field flow to the surface of the tube 1 due to the skin effect, and are disturbed by scratches formed on the surface of the tube 1. An RF-ECT detection signal (current) generated by a voltage induced in the coils 10111 to 1011n and 10121 to 1012n of the excitation / detection coil 101 by a magnetic flux generated by the eddy current including the disturbance is input from the detection input terminal 112. Then, the amount of disturbance of the n-channel detection signal (disturbance of eddy current due to scratches) is determined.

  The ECT signal processing system 12 outputs an ECT excitation current of about several tens of kHz to several hundreds of kHz from the excitation output terminal 121 and the coils 10111 to 1011n and 10121 of the excitation / detection coil 101 via the resistors 13 and 14. -1012n and an alternating direct magnetic field is generated by the coils 10111 to 1011n and 10121 to 1012n. The eddy current generated in the tube 1 by the electromagnetic induction effect by the direct magnetic field is disturbed by the scratch formed on the inner surface of the tube 1. Then, an ECT detection signal (current) generated by a voltage induced in the coils 10111 to 1011n and 10121 to 1012n by the magnetic flux generated by the eddy current including the disturbance is input from the detection input terminal 122, and this n-channel detection signal is input. The amount of disturbance (disturbance of eddy current due to scratches) is determined.

  When there is no scratch or the like in the tube 1, this eddy current is not disturbed, but when there is a scratch or the like, the eddy current is disturbed.

  Since the functions of the resistors 13 and 14 connected to the ECT exciting current supply system are the same as those in the above-described embodiment, a duplicate description is omitted.

  FIG. 13 is a functional block diagram of an eddy current flaw detection system in which the configurations of the RF-ECT signal processing system and the RF-ECT signal processing system are simplified.

  In this eddy current flaw detection system, excitation of the multi-coil type inspection probe 10 is performed by using a distributor to connect one channel detection input terminal 112 of the RF-ECT signal processing system 11 and one channel detection input terminal 122 of the ECT signal processing system 12. The detection coil 101 is configured to be selectively input-connected to the n-channel coils 10111 to 1011n and 10121 to 1012n.

  The distributor 26 connects the n-channel input terminal 261 to the n-channel coils 10111 to 1011n and 10121 to 1012n in the excitation / detection coil 101 of the multi-coil type inspection probe 10, and connects the 1-channel output terminal 262 to the RF. -Connect to one channel detection input terminal 112 of the ECT signal processing system 11 and one channel detection input terminal 122 of the ECT signal processing system 12.

  The distributor 26 connects the detection input terminal 112 of one channel of the RF-ECT signal processing system 11 and the detection input terminal 122 of one channel of the ECT signal processing system 12 to the excitation / detection coil 101 of the inspection probe 10. The detection signals induced in the n-channel coils 10111 to 1011n and 10121 to 1012n are selectively and sequentially connected to the channel coils 10111 to 1011n and 10121 to 1012n, and the detection signals of the RF-ECT signal processing system 11 and the ECT signal processing system 12 are detected. By sequentially inputting the signals to the detection input terminals 112 and 122 of one channel, the RF-ECT signal processing system 11 and the ECT signal processing system 12 sequentially perform detection processing.

  In the eddy current flaw detection system in this embodiment, the number of detection processing systems in the RF-ECT signal processing system 11 and the ECT signal processing system 12 is reduced, and the configuration of the RF-ECT signal processing system 11 and the ECT signal processing system 12 is reduced. It can be simplified.

  FIG. 14 is a diagram showing the flow of the excitation current (excitation magnetic flux) and detection signal during flaw detection in this embodiment.

  For flaw detection, the inspection probe 10 is inserted into the flaw detection target tube 1 in the same manner as in the above-described embodiment.

  The RF-ECT signal processing system 11 outputs an excitation current of about several hundred Hz from the excitation output terminal 111 and supplies the excitation current to the excitation coils 102 and 103. The excitation coils 102 and 103 allow the AC indirect magnetic field (RF- ECT excitation magnetic flux) is generated. Eddy currents generated in the tube 1 due to the electromagnetic induction effect by the indirect magnetic field flow to the surface of the tube 1 due to the skin effect, and are disturbed by scratches formed on the surface of the tube 1. The RF-ECT detection signal (current) generated by the voltage induced in the coils 10111 to 1011n and 10121 to 1012n of the excitation / detection coil 101 by the magnetic flux generated by the eddy current including the disturbance is selected via the distributor 26. Therefore, the detection signal is sequentially input from the detection input terminal 112, and the amount of disturbance of the n-channel detection signal (disturbance of eddy current due to scratches) is determined.

  The ECT signal processing system 12 outputs an ECT excitation current of about several tens of kHz to several hundreds of kHz from the excitation output terminal 121 and the coils 10111 to 1011n and 10121 of the excitation / detection coil 101 via the resistors 13 and 14. -1012n and an alternating direct magnetic field is generated by the coils 10111 to 1011n and 10121 to 1012n. The eddy current generated in the tube 1 by the electromagnetic induction effect by the direct magnetic field is disturbed by the scratch formed on the inner surface of the tube 1. The ECT detection signals (currents) generated by the voltages induced in the coils 10111 to 1011n and 10121 to 1012n by the magnetic flux generated by the eddy current including the disturbance are selectively and sequentially detected via the distributor 26. 122, and the amount of disturbance of the n-channel detection signal (disturbance of eddy current due to scratches) is determined.

  Since the functions of the resistors 13 and 14 connected to the ECT exciting current supply system are the same as those in the above-described embodiment, a duplicate description is omitted.

It is a schematic diagram which shows the outline | summary of the indirect magnetic field and direct magnetic field in an eddy current flaw detection. It is a vertical side view of an inspection probe in which RF-ECT and ECT are arranged coaxially in the axial direction. It is the vertical front view and vertical side view which show the multi coil type (a) of the excitation / detection coil in ECT as contrasted with the bobbin coil type (b). It is a vertical side view of the inspection probe for multi-coil type RF-ECT and ECT. It is a functional block diagram of an eddy current flaw detection system using a bobbin coil type inspection probe. It is a figure which shows the flow of the excitation current (excitation magnetic flux) and detection signal in a flaw detection. It is a functional block diagram of an eddy current flaw detection system. It is a wave form diagram of a detection signal. The relationship between the magnitude of the resistance value of the resistor connected in series to the ECT exciting current supply system and the detection characteristic is shown. A flaw detection comparison result (Y signal) in flaw detection using a multi-coil type inspection probe and a bobbin coil type inspection probe is shown. It is a functional block diagram of an eddy current flaw detection system using a multi-coil type inspection probe. It is a figure which shows the flow of the excitation current (excitation magnetic flux) and detection signal in a flaw detection. It is a functional block diagram of an eddy current flaw detection system that simplifies the configuration of an RF-ECT signal processing system and an ECT signal processing system. It is a figure which shows the flow of the excitation current (excitation magnetic flux) and detection signal in a flaw detection.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Ferromagnetic tube, 10 ... Inspection probe, 101 ... Excitation / detection probe, 1011, 1012 ... Coil, 102, 103 ... Excitation coil, 11 ... RF-ECT signal processing system, 111 ... Excitation output terminal, DESCRIPTION OF SYMBOLS 112 ... Detection input terminal, 12 ... ECT signal processing system, 121 ... Excitation output terminal, 122 ... Detection input terminal, 13, 14 ... Resistor, 22 ... Detection signal acquisition part, 2201 ... Excitation signal oscillator, 2202 ... Phaser, 2203 ... Bridge circuit, 2204 ... Amplifier circuit, 2205 ... Phase detector circuit, 2206 ... Filter, 2207 ... X, Y processing circuit, 2208 ... Excitation signal oscillator, 2209 ... Phase shifter, 2210 ... Bridge circuit, 2211 ... Amplifier circuit, 2212 ... phase detection circuit, 2213 ... filter, 2214 ... X, Y processing circuit, 23 ... recording unit, 24 ... evaluation unit, 25 ... determination process Part.

Claims (4)

An RF-ECT flaw detection system in which the excitation coil of the inspection probe is connected to the excitation output terminal of the RF-ECT signal processing system and the detection coil is connected to the detection input terminal, and the excitation and detection coil of the inspection probe is an ECT signal processing system. In an eddy current flaw detection system having an ECT flaw detection system connected to the excitation output terminal and the detection input terminal of
The ECT flaw detection system connects the detection coil of the RF-ECT flaw detection system to the detection input terminal of the ECT flaw detection system by using the detection coil in the RF-ECT flaw detection system as the excitation and detection coil. An eddy current flaw detection system, characterized in that it is connected to the excitation output terminal of the ECT flaw detection system via a detector.   2. The eddy current flaw detection system according to claim 1, wherein a resistance value of the resistor is set larger than a value of an internal resistance between excitation output terminals in the ECT flaw detection system. According to claim 1 or 2, in that the RF-ECT flaw system of the detection coil has a configuration in which it was a plurality of coils around the axis are arranged in two rows in a ring to form a coil group in the second column Features an eddy current flaw detection system.   4. The distributor according to claim 3, further comprising: a selector for selectively connecting a detection input terminal for one channel of the RF-ECT signal processing system and a detection input terminal for one channel of the ECT signal processing system to a plurality of coils in the detection coil. An eddy current flaw detection system.

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