JPH06281627A - Method and device for inspecting tubular body - Google Patents

Abstract

PURPOSE:To presumably detect the opening diameter and depth of a detected flaw by finding a Lissajous' waveform between the transmitting and receiving signals of a detection probe and processing Lissajous' phase signals against a scanning location. CONSTITUTION:A storing means 16a stores a first relation index between the half band width of Lissajous' signals on a Lissajous' waveform found between the transmitting and receiving signals of a detection probe 2 as the probe 2 makes scanning and the opening diameter of a flaw in a tubular body and a second relation index between the peak value PPA of the Lissajous' phase signals using the opening diameter as a parameter and the depth of the defect. A flaw detecting signal processing means 16b detects the half width value PPD and the peak value PPA by obtaining the Lissajous' waveform from the transmitting and receiving signals detected in the axial direction of an actual tubular body 3 and the Lissajous' phase signals. A presuming means 16c presumes the opening diameter of the defect 4 based on the width PPD and first relation index and the depth of the flaw 4 from the opening diameter and detected peak value PPA.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for inspecting and diagnosing corrosion of pipes.

[0002]

2. Description of the Related Art As a method of inspecting a tube of this type, a detection probe having a transmitting coil and a receiving coil at different positions in the longitudinal direction is moved in the tube of a conductor, and the coil is made to move by the transmitting coil. A method is known in which a magnetic field is generated in the peripheral portion of the tube and the state of defects existing in the tube is grasped by the eddy current generated in the tube. That is, the state of the defect is grasped by detecting the state of the eddy current disturbed by the defect as the change of the magnetic field formed around the defect by the receiving coil. And, as a device adopting such a method for inspecting a pipe, the above-mentioned detection probe, the pipe introducing device,
Further, there is a pipe inspection device equipped with a power supply, a detection device, and the like.

[0003]

However, in the above-mentioned prior art, since the defect signal intensity depends on the depth of the defect and the opening diameter, the depth of the defect cannot be correctly estimated from only this information. The main purpose was to confirm the presence or absence of defects and their positions. On the other hand, the purpose of such a pipe inspection is to determine whether or not maintenance work is required for this pipe depending on the degree of defects existing in the pipe itself (especially the condition of the defect depth). To do. However, the conventional method and apparatus for detecting a defect cannot achieve this object. Further, the inventors of the present invention, in Japanese Patent Application No. 4-60796, utilize the defect signal obtained by the above-mentioned method, and determine the aperture diameter of the defect and the defect opening diameter from the phase change state (defect signal width and defect signal intensity width). A method of estimating the depth is proposed. However, when only the phase of the defect signal is used as the judgment material as in this method, the defect signal may change depending on the aperture diameter of the defect even if the defect depth is the same. Can be difficult to estimate.

Therefore, it is an object of the present invention to detect the presence or absence of a defect and the position thereof, and further to estimate and detect the aperture diameter and the defect depth of the detected defect. It is to obtain an inspection method of a pipe body and its device.

[0005]

Means for Solving the Problems A feature of the pipe inspection method according to the present invention that achieves this object is that a transmission signal transmitted from a transmission coil and a reception signal detected by a reception coil according to scanning of a detection probe. And a Lissajous waveform between the scanning position and the Lissajous phase signal of the Lissajous waveform with respect to the scanning position, the peak value PPA of the Lissajous phase signal and the signal half-width PPD are detected, and a defect is detected from the signal half-width PPD of the Lissajous phase signal. Along with estimating the aperture, a relational index between the peak value PPA of the Lissajous phase signal and the defect depth with the aperture size of the defect as a parameter is obtained in advance, and the estimated aperture size is detected by referring to the relational index. Peak value PPA of Lissajous phase signal
And more to estimate the defect depth.

Further, the tube inspection apparatus is characterized in that a defect is detected in the Lissajous waveform obtained between the transmission signal transmitted from the transmission coil and the reception signal detected by the reception coil in accordance with the scanning of the detection probe. The peak value PPA of the Lissajous phase signal using the aperture as a parameter and the relationship index between the defect depth are obtained in advance, and a storage means for storing the relationship index is provided. From the Lissajous phase signal of the Lissajous waveform with respect to the scanning position, the peak of the Lissajous phase signal is obtained. The flaw detection signal processing means for detecting the value PPA and the signal half-value width PPD and the signal half-value width PPD of the Lissajous signal are used to estimate the opening diameter of the defect, and the relation index is referred to detect the estimated opening diameter. It is provided with a peak value PPA of the Lissajous phase signal and an estimation means for further estimating the defect depth. Their action and effect is next street.

[0007]

The flaw detection signal obtained by the above-mentioned technique is, as its unique characteristic, information in which the half width PPD of the Lissajous phase signal of the Lissajous waveform in the tube axis direction is related only to the aperture diameter of the defect. The peak value PPA of the Lissajous phase signal is information related to the defect opening diameter and the defect depth. Therefore, in the present application, this characteristic is positively utilized to accurately detect the defect depth, which is very important information for maintenance and management of the pipe body. That is, in the tube inspection method of the present application, first, a Lissajous waveform is drawn between the transmission signal transmitted from the transmission coil and the reception signal detected by the reception coil in accordance with the scanning of the detection probe. Then, a Lissajous phase signal for the scanning position is obtained from this Lissajous waveform, and the peak value PPA and the signal half-width PPD of the Lissajous phase signal are detected. Signal half-width PPD of the obtained Lissajous phase signal
The opening diameter of the defect is estimated by using the estimated value and the peak value PPA of the Lissajous phase signal and the defect depth, which are obtained separately based on the peak value PPA of the Lissajous phase signal, as parameters. An estimated value of the defect depth can be obtained from the related index. Further, in order to execute this method, the pipe inspection device is provided with a storage unit, a flaw detection signal processing unit, and an estimation unit.

[0008]

Therefore, it is possible to detect the presence or absence and the position of a defect, and to accurately estimate the aperture diameter and the defect depth of the detected defect to obtain this information. A body inspection method and an apparatus therefor are obtained, and according to the present invention, it is possible to accurately estimate information on a defect depth from which a defect aperture information element is removed from a flaw detection signal.

[0009]

Embodiments of the present application will be described with reference to the drawings. In the inspection of the pipe body, the detection probe 2 provided in the inspection device 1 is inserted into the pipe body 3 and is moved to detect the state of the defect 4 on the outer peripheral portion of the pipe body 3. It is a thing. Explaining the principle of the inspection method, as shown in FIG. 1, the defect 4 is inspected by using the transmitting coil 5 and the receiving coil 6 arranged at different positions in the longitudinal direction of the detection probe 2. However, in the inspection, an alternating current of about 35 Hz is applied to the transmission coil 5, and an eddy current 7 is generated in the tube body 3. And defect 4
Indirect magnetic field 8 generated by eddy current 7 disturbed by the presence of
However, the defect 4 on the outer surface of the tube is grasped by the receiving coil 6 and the phase change of the magnetic field is grasped. Here, in the illustrated embodiment, the axis of the transmitting coil 5 and the axis of the tube 3 are arranged in parallel, and the axis of the receiving coil 6 is also arranged in parallel with the axis of the tube 3. Has been done.

Before explaining the tube inspection method of the present application, a schematic configuration of the entire apparatus 1 will be described with reference to FIG. The tube inspection device 1 includes the above-described detection probe 2, a cable 9 provided with the detection probe 2 at the tip, and the cable 9.
And a cable automatic feeding device 11 for feeding a cable, and a traveling device controller 1 for issuing a traveling command to the feeding device 11.
Equipped with 2. Further, the device 1 is provided with a defect inspection device 13 that controls the transmission coil 5 and the reception coil 6 provided in the detection probe 2 and obtains detection information. A processing device 14 for processing information such as in-tube position information and detection output information is provided, and the detection information is sent to the processing device, processed, and output by the output device 15.

The above is the schematic structure of the pipe body inspection apparatus 1. The following is a structure of the defect opening diameter and defect depth estimation method and its processing means 16 which employ the pipe body 3 inspection method of the present application. Will be described. Here, the processing means 16 is built in the processing device 14 described above.

That is, the processing means 16 has a signal half-width P of the Lissajous phase signal in the Lissajous waveform obtained between the transmission signal transmitted from the transmission coil and the reception signal detected by the reception coil in accordance with the scanning of the detection probe.
A first relation index (actually a relation graph or table as shown in FIG. 4) that stores the relation between the PD and the defect opening diameter, and the peak value PPA of the Lissajous phase signal with the defect opening diameter as a parameter and the defect depth. The storage means 16a stores a second relation index (actually, a relation graph or table as shown in FIG. 5). In various actual defects (corrosion defects of approximately conical shape formed on the outer periphery of the tube),
When the relationship with the peak value PPA of the Lissajous phase signal with the opening diameter of the defect as a parameter is obtained, the relationship between the two is uniquely shown with respect to the change of the opening diameter regardless of the change of the defect depth, as shown in FIG. Then, get on the one relation line. On the other hand, the peak value PPA of the Lissajous phase signal and the defect depth become asymptotic to one relational line (the line located at the top of FIG. 5) as the depth decreases, but the depth increases. As a result, the relational lines are positioned in the upper and lower parts of the drawing in terms of position, and can be expressed for the first time using the opening diameter as a parameter. Here, these pieces of information are obtained by analyzing the signal states of a plurality of defects in advance before the inspection. On the other hand, in the actual detection, in the signal detected along the tube axis direction of the tube body 3, the Lissajous waveform as shown in FIG. 6 is obtained by the transmission signal transmitted from the transmission coil and the reception signal detected by the reception coil. And from this,
A Lissajous phase signal as shown in is obtained. The horizontal axis of FIG. 7 is the position of the probe, and the vertical axis is the phase. From this Lissajous phase signal, the signal half-width PPD of the Lissajous phase signal (indicated by PPD in FIG. 7) and the peak value PPA of the Lissajous phase signal (PPA in FIG. 7) are obtained.
And) are detected. The flaw detection signal processing means 16b is responsible for these processes. Further, the aperture diameter of the defect is estimated from the signal full width at half maximum PPD of the Lissajous phase signal based on the above-mentioned first relation index, and the estimated aperture diameter of the defect and the detected Lissajous phase based on the second relation index. The estimation unit 16c is configured to estimate the defect depth from the peak value PPA of the signal.

Here, in such a flaw detection method using magnetism with the transmitting and receiving coils, the signal full width at half maximum PPD of the Lissajous phase signal in the tube axis direction is information related only to the aperture diameter of the defect. Therefore, it is effectively used that the peak value PPA of the Lissajous phase signal is information that is substantially related to the opening diameter and the defect depth of the defect. Therefore, the method disclosed in the present application positively utilizes this feature to accurately detect the defect depth, which is very important information for maintenance and management of the pipe body. Hereinafter, FIG. 3, FIG.
The procedure of the tubular body inspection method of the present application will be described with reference to FIGS. 5, 6, and 7. Here, FIG. 3 shows a defect state estimation procedure flow, FIG. 4 shows the relationship between the signal half-width PPD of the Lissajous phase signal and the defect opening diameter, and FIG. 5 uses the defect opening diameter as a parameter. The relationship between the peak value PPA of the Lissajous phase signal and the defect depth is shown.

The processing procedure is itemized. <Flow of Defect Depth Estimation> (a) Input of flaw detection signal (consisting of transmission signal and reception signal) (b) Lissajous waveform is obtained by flaw detection signal processing means 16b, and Lissajous phase is obtained from the Lissajous phase signal of the Lissajous waveform. The signal half-width PPD and peak value PPA of the signal are obtained. As shown in FIG. 7, the peak value PPA of the Lissajous phase signal is the maximum value of the phase and the phase 0.
The signal full width at half maximum PPD is a distance at a pair of positions which is half the peak value PPA. (C) The aperture diameter of the defect is estimated based on the first relationship index shown in FIG. 4 from the signal half-width PPD of the Lissajous phase signal by the estimation means 16c (shown by a chain line arrow in FIG. 4). (D) The defect depth is estimated by the estimating means 16c based on the peak value PPA of the Lissajous phase signal based on the second relation index shown in FIG. 5 (shown by a chained arrow in FIG. 5). In this estimation process, the opening diameter of the defect obtained in the step (c) is used. For example, the full width at half maximum of the Lissajous phase signal PPD 1.48c
When the peak value PPA of the m Lissajous phase signal is 57 degrees, it is estimated that the defect opening diameter is 1.5 cm and the defect depth is 0.35 cm. Here, the first relation index and the second relation index are uniquely determined by the coil arrangement configuration, the general shape of the defect, the generation state of the eddy current, and the like. It was confirmed experimentally and by simulation by the inventor.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

[Figure 1] Principle diagram of inspection principle

FIG. 2 is a diagram showing a configuration of an inspection device.

[Fig. 3] Defect state estimation procedure flow

FIG. 4 is a diagram showing a relationship between a signal half-width PPD of a Lissajous phase signal and a defect opening diameter.

FIG. 5 is a diagram showing a relationship between a peak value PPA of a Lissajous phase signal and a defect depth.

FIG. 6 is a diagram showing a Lissajous waveform.

FIG. 7 is a diagram showing a Lissajous phase signal.

[Explanation of symbols]

 2 Detection probe 3 Tubular body 4 Defect 5 Transmission coil 6 Reception coil 16a Storage means 16b Flaw detection signal processing means 16c Estimating means PPA Peak value PPD Signal half width

Claims (2)

[Claims] 1. A detection probe (2) equipped with a transmission coil (5) and a reception coil (6) at different positions in the longitudinal direction is moved within a conductor tube (3), and the transmission coil (3) is moved. A magnetic field is generated in the peripheral part of 5), and the magnetic field formed in the tubular part with respect to the receiving coil (6) is detected by the receiving coil (6) to detect a defect (4) existing in the tubular part. A method for inspecting a tubular body for detecting the situation of, wherein a Lissajous waveform is obtained between a transmission signal transmitted from the transmission coil and a reception signal detected by the reception coil in accordance with the scanning of the detection probe. ,
From the Lissajous phase signal of the Lissajous waveform for the scanning position, the peak value PPA of the Lissajous phase signal is obtained.
And the signal half-value width PPD are detected, the opening diameter of the defect is estimated from the signal half-value width PPD of the Lissajous phase signal, and the peak value PPA of the Lissajous phase signal and the defect depth are set in advance using the opening diameter of the defect as a parameter. A method for inspecting a tubular body, wherein a relationship index between the defect diameter is estimated and a defect depth is estimated from the estimated opening diameter and the detected peak value PPA of the Lissajous phase signal with reference to the relationship index. 2. A detection probe (2) having a transmission coil (5) and a reception coil (6) at different positions in the longitudinal direction is provided, and the detection probe (2) is moved in a tubular body (3) of a conductor and at the same time. A magnetic field is generated in the transmitting coil (5), and the magnetic field formed in the tubular portion with respect to the receiving coil (6) is detected by the receiving coil (6) to detect defects (4) present in the tubular portion. A device for inspecting a tube body for detecting a condition, wherein a Lissajous is obtained between a transmission signal transmitted from the transmission coil and a reception signal detected by the reception coil with the scanning of the detection probe (2). The waveform includes a storage unit (16a) that stores in advance a relational index between the peak value PPA of the Lissajous phase signal with the aperture diameter of the defect as a parameter and the defect depth. The flaw detection signal processing means (16b) for detecting the peak value PPA of the Lissajous phase signal and the signal half-value width PPD, and estimating the opening diameter of the defect from the signal half-value width PPD of the Lissajous phase signal, and refer to the relation index. Then, the tubular body inspection apparatus comprising the estimated opening diameter, the peak value PPA of the detected Lissajous phase signal, and the estimation means (16c) for estimating the defect depth.