JP2017009549A - Non destructive testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non destructive testing device that can extract a weak and defective signal in the inside of piping and can make accurate inspection of heat-insulating piping for detects.SOLUTION: A non destructive testing device 100 includes: an excitation part 10; a magnetism sensor 20; a pulse power source 40; a magnetism sensor circuit 50; a moving mechanism 60; and a controller 70. The excitation part 10 generates a magnetic flux MF0, which enters heat-insulating piping 1 into a direction substantially perpendicular to a center axis AX of the piping 1 and penetrates a piping body 1a of the piping 1. Since the magnetic flux MF0 with a relatively high density is thus caused to enter the inner piping body 1a, a defective signal can be extracted relatively easily from the body 1a, which can increase the accuracy and the reliability of detection of defects of the body 1a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a non-destructive inspection apparatus that non-destructively inspects defects in heat-insulating piping by magnetism.

  As a method of non-destructively inspecting defects in heat insulation pipes, magnetic flux extending in the axial direction of the heat insulation pipes is generated by winding a plurality of coils on the outer peripheral face of the heat insulation pipes and arranged on the outer peripheral face of the heat insulation pipes. It has become known to use a detection coil that detects a magnetic field in the axial direction of a heat insulating pipe and extract a signal change due to a defect by lock-in detection (see Patent Document 1).

  In addition, as another method for magnetically inspecting a pipe defect, although it is from the inside of the pipe, for example, a tube flaw detector having an array eddy current flaw sensor is used to sequentially switch and scan the array eddy current flaw sensor. In some cases, defects are extracted (see Patent Document 2).

  The apparatus of the above-mentioned patent document 1 is to measure a defect of a pipe by putting a magnetic flux parallel to the central axis with respect to the pipe. When the outer plate is a magnetic material, the defect of the outer plate is included in the defect signal of the pipe. A signal is superimposed and detected. At this time, if the pipe defect signal is sufficiently larger than the defect signal of the exterior plate, it is possible to detect the thinning of the heat insulation pipe, but generally the defect signal of the outer exterior plate becomes large. In other words, a magnetic flux with sufficient density cannot be put into the inner piping, and in order to extract a weak defect signal in the inner piping, complicated signal processing is required and accuracy is lowered. There is. In addition, since the coil is wound around the outer peripheral surface of the heat insulating pipe, it is necessary to reattach the non-destructive inspection device to the heat insulating pipe, that is, to rewind the coil every time inspection is performed.

  The apparatus of Patent Document 2 is for inspecting piping defects from the inside of the pipe, and when trying to inspect a heat insulating pipe having an exterior plate made of a magnetic material from the outside in a nondestructive manner, it is the same as that of Patent Document 1. Problems arise. In other words, a magnetic flux with sufficient density cannot be put into the inner pipe, and in order to extract a weak defect signal in the inner pipe, complicated signal processing is required and accuracy is lowered. There is.

Japanese Patent No. 4766472 JP-A-8-2013347

  It is an object of the present invention to provide a nondestructive inspection apparatus that can extract a weak defect signal of an inner pipe and can inspect a defect of a heat insulating pipe with high accuracy.

  In order to solve the above-described problems, a nondestructive inspection apparatus according to the present invention includes an excitation unit that enters a heat insulation pipe substantially perpendicular to the central axis of the heat insulation pipe and generates a magnetic flux penetrating the pipe body of the heat insulation pipe. A magnetic sensor for detecting a magnetic signal generated by the thinning; and a signal processing unit for calculating the detection output of the magnetic sensor.

  In the non-destructive inspection apparatus, the excitation part enters the heat insulation pipe substantially perpendicular to the central axis of the heat insulation pipe and generates a magnetic flux penetrating the pipe main body of the heat insulation pipe. Magnetic flux is introduced, and it becomes relatively easy to extract a defect signal from the inner pipe body. Thereby, the precision and reliability of the detection with respect to the defect of a piping main body can be improved.

  In a specific aspect or aspect of the present invention, in the nondestructive inspection apparatus, the excitation unit is disposed so as to cover a part of the heat insulating pipe while being partially opened. That is, the excitation unit is arranged so as to have a ring-opened cylindrical outer shape and partially surround the heat insulating pipe. In this case, it is possible to improve the assembling property at the measurement site with respect to the mounting of the excitation unit to the heat insulating pipe.

  In another aspect of the present invention, the excitation unit includes a coil for passing a current and a core member for guiding a magnetic flux formed by the coil, and the core member is a pair of magnetic poles arranged so as to sandwich the heat insulating pipe. Has a part. In this case, the magnetic flux generated from the pair of magnetic pole portions enters the heat insulation pipe so as to cross the heat insulation pipe.

  In still another aspect of the present invention, a pulsed excitation current is supplied to the coil, and the signal processing unit analyzes the detection output of the magnetic sensor in synchronization with the excitation current. Thereby, S / N ratio can be raised.

  In still another aspect of the present invention, the excitation part extends in an arc shape along the periphery of the heat insulating pipe. In this case, the excitation part is composed of one or more portions extending in an arc shape, and assembling at the measurement site can be improved with respect to the mounting of the excitation part to the heat insulating piping.

  In still another aspect of the present invention, the core member extends in a semicircular shape along the periphery of the heat insulating pipe, and the pair of magnetic pole portions are formed at the pair of end portions of the core member. In this case, the excitation unit can have a simple structure, and workability at the measurement site can be improved. In addition, it is not necessary to separately prepare the excitation portions for the S pole and the N pole, and the design, manufacture, and the like are facilitated.

  In yet another aspect of the present invention, the core member is composed of a pair of semicircular opposing portions arranged with the heat insulating piping interposed therebetween, and the pair of magnetic pole portions are respectively distributed to the pair of opposing portions, and the heat insulating piping is provided. It extends continuously along the periphery of the, or a plurality of them are continuously arranged. In this case, it becomes easy to avoid the completion of the local magnetic flux, and a relatively high density magnetic flux can be put into the inner pipe body.

  In still another aspect of the present invention, the excitation unit is provided in the vicinity of a plurality of locations along the central axis direction of the heat insulating pipe. In this case, the magnetic flux leaking to the outside in the central axis direction of the heat insulating pipe can be reduced, and the magnetic flux penetrating the pipe main body can be easily generated.

  In still another aspect of the present invention, the magnetic sensors are provided at a plurality of locations along a radial direction that passes through the central axis of the heat insulating pipe and is perpendicular to the central axis. In this case, it becomes easy to specify the position of the defect in the radial direction, and it becomes easy to distinguish the scratch on the exterior plate from the scratch on the pipe body.

  In still another aspect of the present invention, the magnetic sensors are provided at a plurality of locations at different positions in the central axis direction of the heat insulating pipe. In this case, the magnetic flux corresponding to the position of the heat insulating pipe in the central axis direction can be detected, and more various inspections are possible.

  In still another aspect of the present invention, the excitation portion and the magnetic sensor are covered with a heat shield pipe and a magnetic shield member. In this case, the completion of the local magnetic flux can be avoided and the disturbance can be blocked, so that the defect detection accuracy can be improved.

  In still another aspect of the present invention, the exciter is further rotatable along the periphery of the heat insulating pipe, and further includes a moving mechanism that allows the exciter to move along the central axis direction of the heat insulating pipe. In this case, the detection of defects along the periphery of the heat insulating pipe becomes easier.

It is a figure by the side of the piping section explaining the nondestructive inspection device of a 1st embodiment notionally. (A) And (B) is a conceptual side view and sectional drawing explaining the nondestructive inspection apparatus shown in FIG. It is a block diagram explaining the basic composition of a control part among the nondestructive inspection devices of Drawing 1. It is a flowchart explaining an example of a piping inspection method. It is a figure which illustrates notionally the nondestructive inspection apparatus of 2nd Embodiment. (A) is sectional drawing explaining the nondestructive inspection apparatus of 3rd Embodiment, (B) is a partial expanded sectional view explaining the cross-section of an excitation part. (A) is sectional drawing explaining the nondestructive inspection apparatus of 4th Embodiment, (B) is the partial expansion perspective view explaining a part of excitation part. It is a figure which illustrates notionally the nondestructive inspection apparatus of 5th Embodiment. It is a figure which illustrates notionally the nondestructive inspection apparatus of 6th Embodiment. It is a figure explaining a detection operation notionally. It is a figure which illustrates notionally the nondestructive inspection apparatus of 7th Embodiment.

[First Embodiment]
The nondestructive inspection apparatus 100 shown in FIG. 1 and the like applies a pulse magnetic field to the heat insulation pipe 1 to be inspected and detects the pulse magnetic field formed in the heat insulation pipe 1, thereby reducing defects that are defects in the heat insulation pipe 1. It is to inspect meat. Here, the thinning of the heat insulating pipe 1 means deterioration of the pipe such as corrosion, fatigue, and cracks.

  The heat insulation pipe 1 to be inspected has a steel pipe main body 1a, a heat insulating material 1b covering the periphery of the pipe main body 1a, and an exterior plate 1c covering the heat insulating material 1b. That is, the heat insulating pipe 1 has a triple pipe structure in which the pipe main body 1a is covered with the heat insulating material 1b and the exterior plate 1c in a cylindrical shape. Defects occur as thinning inside or outside the pipe body 1a.

  The nondestructive inspection apparatus 100 is configured to cover the heat insulating piping, and includes an excitation unit 10, a magnetic sensor 20, a pulse power source 40, a magnetic sensor circuit 50, a moving mechanism 60, and a control unit 70. In the nondestructive inspection apparatus 100, the excitation unit 10 and the magnetic sensor 20 function as the inspection unit 80. The inspection unit 80 is movable with respect to the heat insulating pipe 1, and the magnetic sensor 20 detects the magnetic field generated by the excitation unit 10 in the presence of the heat insulating pipe 1.

The excitation unit 10 generates a pulse magnetic field. The exciter 10 includes a coil 10a through which a current flows and a core member 10b that guides a magnetic flux formed by the coil 10a in a target direction. The coil 10a is made of copper, for example, and the core member 10b is made of ferrite, for example. The exciter 10, that is, the core member 10 b extends in an arc shape along the periphery of the heat insulating pipe 1. Specifically, the core member 10 b extends in a semicircular shape along the periphery of the heat insulating pipe 1. Thus, the core member 10b is not formed in a ring shape, and the half is opened, so that the exciter 10 can be easily attached to the heat insulating pipe 1. That is, the assemblability at the measurement site where the work of setting the excitation unit 10 around the heat insulating pipe 1 is performed can be improved.
In addition, it can be seen that the excitation part 10 is arrange | positioned so that the circumference | surroundings of the heat insulation piping 1 may be covered open partially. That is, the excitation unit 10 has an open cylindrical shape and is disposed so as to partially surround the heat insulating pipe 1. As a result, the lower part of the excitation unit 10 is opened, and the lower surface of the heat insulating pipe 1 is exposed to the outside of the excitation unit 10.

  The core member 10b includes a main body portion 11a around which a coil 10a is wound, and a pair of yoke portions 11b and 11b extending from the main body portion 11a. A pair of magnetic pole portions 10p and 10q disposed so as to sandwich the heat insulating pipe 1 are provided at a pair of end portions 12a and 12b of the core member 10b, that is, at the tip ends of the pair of yoke portions 11b and 11b. The pair of magnetic pole portions 10p and 10q are an N pole and an S pole, respectively, and project toward the outer peripheral side surface 1s that is the surface of the heat insulating pipe 1.

The magnetic flux MF0 extending from the one magnetic pole portion 10p enters the heat insulating pipe 1 so as to be substantially orthogonal to the central axis AX of the heat insulating pipe 1, and enters or enters one side (−X side) of the pipe main body 1a. The magnetic flux MF0 is greatly bent in the pipe body 1a and travels along the pipe body 1a. On the opposite side (+ X side) of the pipe main body 1a, the magnetic flux MF0 that has passed through the pipe main body 1a is emitted to the outside, and the magnetic flux MF0 thus emitted is substantially orthogonal to the central axis AX outside the heat insulating pipe 1. To the other magnetic pole portion 10q. That is, the exciting unit 10 can generate the magnetic flux MF0 penetrating the pipe body 1a.
In FIG. 1, for convenience of explanation, only the magnetic flux MF0 penetrating the pipe main body 1a is drawn. However, the magnetic flux MF0 penetrating the pipe main body 1a is included in the magnetic flux from one magnetic pole portion 10p toward the other magnetic pole portion 10q. In addition, there is a magnetic flux that penetrates only the exterior plate 1c of the heat insulating pipe 1, and there is a magnetic flux that extends along the outside of the exterior plate 1c. By arranging the pair of magnetic pole portions 10p and 10q so as to face each other with the heat insulating pipe 1 interposed therebetween, in particular, by arranging them at the opposite positions across the central axis AX, the pipe main body 1a can be obtained without increasing the applied current to the coil 10a. Can be increased. Further, by bringing the pair of magnetic pole portions 10p and 10q closer to the heat insulating pipe 1, the magnetic flux MF0 penetrating the pipe main body 1a can be increased.

The magnetic sensor 20 detects, for example, a magnetic field in the circumferential direction orthogonal to the central axis AX of the heat insulating pipe 1 and a magnetic field in the radial direction orthogonal to the central axis AX of the heat insulating pipe 1 as magnetic signals. Thereby, the magnetic sensor 20 can detect a magnetic field transmitted through the heat insulating pipe 1 or a change in the magnetic field. In the example of FIG. 1, one magnetic sensor 20 is disposed inside the main body 11a around which the coil 10a is wound. Although not shown, the inspection unit 80 is provided with a support for supporting the excitation unit 10 and the magnetic sensor 20, and the magnetic sensor 20 is relatively stable with respect to the excitation unit 10. It is fixed to. As the magnetic sensor 20, for example, a TMR sensor, an AMR sensor, or the like is used.
As shown in the figure, when the magnetic sensor 20 is disposed inside the main body 11a, that is, the magnetic sensor 20 is disposed close to the outer peripheral side surface 1s of the heat insulating pipe 1 and at a substantially equidistant position from the pair of magnetic pole portions 10p and 10q. In this case, at the position of the magnetic sensor 20, a parallel magnetic flux is formed along the circumferential direction (X direction in the drawing) of the outer peripheral side surface 1s of the heat insulating pipe 1. Therefore, when a defect exists in the portion of the pipe body 1a close to the magnetic sensor 20, that is, when a defect exists in the pipe portion in the -Y direction of the magnetic sensor 20, the magnetic field or the disturbance of the magnetic field due to the defect is related to the X direction. Although the S / N ratio decreases due to the influence of the excitation unit 10 and is difficult to observe, it is observed relatively strongly in the Y direction.
The position of the magnetic sensor 20 is not limited to the inside of the main body portion 11a, but can be various places close to the outer peripheral side surface 1s of the heat insulating pipe 1. From the viewpoint of excluding the influence due to the bias of the excitation unit 10, the output value of the magnetic sensor 20 when there is no defect can be used as the reference value. That is, the disturbance component of the magnetic field due to the defect can be extracted as a difference obtained by subtracting the reference value from the detection value where the defect may exist.

  The inspection unit 80 may be provided with a magnetic shield member that covers the excitation unit 10 and the magnetic sensor 20 in order to block disturbance.

  The pulse power supply 40 applies a pulse voltage to the coil 10 a of the excitation unit 10. The pulse power supply 40 outputs a square wave as a pulsed excitation current, and drives the excitation unit 10 at a predetermined frequency and duty ratio. The pulse power supply 40 can also change the direction of the current flowing through the coil 10a as appropriate.

  The magnetic sensor circuit 50 drives the magnetic sensor 20 and measures a magnetic field or a magnetic field. The magnetic sensor circuit 50 measures the strength of the magnetic field or the strength of the magnetic field with respect to the desired magnetic direction generated by the excitation unit 10 based on the detection output of the magnetic sensor 20.

The moving mechanism 60 can move the inspection unit 80 in the direction of the central axis AX along the outer peripheral side surface 1 s of the heat insulating pipe 1. The moving mechanism 60 can also rotate and move the inspection unit 80 around the central axis AX along the outer peripheral side surface 1 s of the heat insulating pipe 1. By moving the inspection unit 80 in the direction of the central axis AX, inspection along the longitudinal direction of the heat insulating pipe 1 can be performed. In addition, by rotating the inspection unit 80 about the central axis AX, it is possible to inspect in the circumferential direction along the cross section of the heat insulating pipe 1.
The moving mechanism 60 is not limited to one that automatically operates under the control of the control unit 70, and may be one that manually operates, for example, one that uses wheels or rails.

  The control unit 70 operates the pulse power source 40, the magnetic sensor circuit 50, and the like to drive the excitation unit 10 and the magnetic sensor 20, thereby performing a detection operation. In addition, the control unit 70 operates the moving mechanism 60 to move the inspection unit 80. Further, the control unit 70 analyzes the response of the pulse magnetic field detected by the magnetic sensor 20. That is, the control unit 70 analyzes the detection output of the magnetic sensor 20 in synchronization with the excitation current from the pulse power supply 40 as a signal processing unit. The control unit 70 determines the presence or absence of a defect in the heat insulating pipe 1 by calculating the detection output of the magnetic sensor 20.

  Hereinafter, the control unit 70 will be specifically described. As shown in FIG. 3, the control unit 70 includes a display unit 71, an input unit 72, a storage unit 73, an interface unit 74, and a main control unit 75.

The main control unit 75 can exchange data with the display unit 71, the input unit 72, the storage unit 73, and the interface unit 74. The main control unit 75 processes data input via the input unit 72, the storage unit 73, etc. based on an instruction or program from the input unit 72 operated by the operator, and the pulse power supply 40, the magnetic sensor circuit 50, etc. Operate other devices. Further, the main control unit 75 processes or determines magnetic data obtained via the interface unit 74 based on an instruction or program from the input unit 72.
The display unit 71 includes a display or the like, and performs display to be presented to the operator based on an output signal from the main control unit 75.
The input unit 72 includes a keyboard, a touch panel, and the like, and outputs an instruction from the operator to the main control unit 75.
The storage unit 73 can store a program for operating the control unit 70, magnetic data detected by the magnetic sensor 20, and the like.
The interface unit 74 enables data communication between the main control unit 75 and the pulse power source 40 and the magnetic sensor circuit 50.

Hereinafter, a pipe inspection method using the nondestructive inspection apparatus 100 will be described with reference to FIG.
First, the inspection unit 80 is installed at the site to be inspected of the heat insulating pipe 1 (step S11). The inspection unit 80 can be arranged at a predetermined position by operating the movement mechanism 60 by the control unit 70.

  Next, the magnetic data of the heat insulation piping 1 are acquired and preserve | saved (step S12). The pulse power supply 40 is operated by the control unit 70 and a pulse voltage is applied to the excitation unit 10. Then, the magnetic sensor circuit 50 is operated by the control, and the magnetic field generated in the heat insulating pipe 1 by the excitation unit 10 is detected by the magnetic sensor 20. Here, the magnetic intensity in the desired magnetic direction detected by the magnetic sensor 20 is, for example, a magnetic field intensity (for example, a peak value) in the X direction or the Y direction. Magnetic data detected by the magnetic sensor 20 is stored in the storage unit 73.

  Next, it is determined whether or not a pipe defect signal is included in the magnetic data obtained in step S12 (step S13). When a pipe defect signal equal to or greater than a predetermined threshold is included in the magnetic data (Y in step S13), it is determined that a thinned portion is present in the heat insulating pipe 1, and the storage unit 73 together with position information of the heat insulating pipe 1 is present as a thinned portion. And the corresponding part is displayed on the display unit 71 (step S14). If the magnetic data does not include a pipe defect signal equal to or greater than the predetermined threshold value (N in step S13), it is determined that there is no thinning in the heat insulating pipe 1, and is stored in the storage unit 73 together with the position information as only the normal part. (Step S15).

  Next, when another part of the heat insulating pipe 1 is continuously inspected (Y in step S16), the control unit 70 operates the moving mechanism 60 to move the inspection part 80 to the next inspected part (step S17). , Steps S12 to S15 are repeated. When the inspection of another part of the heat insulating pipe 1 is not performed (N in Step S16), the inspection is terminated.

  In the nondestructive inspection apparatus 100 described above, the excitation unit 10 enters the heat insulation pipe 1 substantially perpendicular to the central axis AX of the heat insulation pipe 1 and generates a magnetic flux MF0 penetrating the pipe body 1a of the heat insulation pipe 1. The magnetic flux MF0 having a relatively high density is put into the pipe main body 1a, and it becomes relatively easy to extract a defect signal from the inner pipe main body 1a. Thereby, the precision and reliability of the detection with respect to the defect of the piping main body 1a can be improved.

[Second Embodiment]
Hereinafter, the nondestructive inspection apparatus of 2nd Embodiment is demonstrated. The nondestructive inspection apparatus of the second embodiment is a partial modification of the nondestructive inspection apparatus of the first embodiment, and matters that are not particularly described are the same as those of the nondestructive inspection apparatus of the first embodiment.

As shown in FIG. 5, the excitation part 10 has a pair of opposing edge parts 12a and 12b as the tip parts of a pair of yoke parts 11b and 11b extending from the main body part 11a. A pair of magnetic pole portions 10p and 10q disposed at opposite positions across the heat insulating pipe 1 are provided at both ends 12a and 12b. The pair of magnetic pole portions 10p and 10q are an N pole and an S pole, respectively, and project toward the outer peripheral side surface 1s that is the surface of the heat insulating pipe 1.
Further, at one end portion 12a, for example, a pair of magnetic pole portions 11p and 12p are arranged adjacently so as to sandwich the magnetic pole portion 10p serving as the N pole from above and below along the circumferential direction, and the outer peripheral side surface of the heat insulating pipe 1 Projecting toward 1s. Similarly, at the other end 12b, a pair of magnetic pole portions 11q and 12q are arranged adjacently so as to sandwich the magnetic pole portion 10q serving as the S pole from above and below along the circumferential direction, and the outer periphery of the heat insulating pipe 1 Projecting toward the side surface 1s. The upper magnetic pole portions 11p and 11q make a pair, and the lower magnetic pole portions 12p and 12q also make a pair.

A magnetic flux MF0 extending between the pair of magnetic pole portions 10p and 10q enters the heat insulating pipe 1 so as to be substantially orthogonal to the central axis AX of the heat insulating pipe 1 and passes through the pipe body 1a. The magnetic flux MF0 emitted from the pipe main body 1a extends outside the heat insulating pipe 1 so as to be substantially orthogonal to the central axis AX and travels toward the other magnetic pole portion 10q. That is, the exciting unit 10 can generate the magnetic flux MF0 penetrating the pipe body 1a.
A main magnetic flux MF1 extending between the pair of magnetic pole portions 11p and 11q enters the heat insulating pipe 1, but does not penetrate the pipe main body 1a. Similarly, the main magnetic flux MF1 extending between the pair of magnetic pole portions 12p and 12q enters the heat insulating pipe 1, but does not penetrate the pipe main body 1a. Therefore, the outer magnetic flux MF1 hardly contributes directly to the inspection of defects formed in the pipe body 1a. However, the magnetic flux MF1 that does not penetrate the pipe main body 1a sandwiches the magnetic flux MF0 that penetrates the pipe main body 1a, and has an effect of confining the magnetic flux MF0 around the center. That is, the upper magnetic pole portions 11p and 11q and the lower magnetic pole portions 12p and 12q are such that the magnetic flux MF0 enters the pipe main body 1a so that the magnetic flux MF0 from the intermediate magnetic pole portions 10p and 10q does not deviate from the pipe main body 1a. I try to make it easier. As a result, the magnetic flux density of the magnetic flux MF0 passing through the pipe body 1a can be increased.

[Third Embodiment]
Hereinafter, the nondestructive inspection apparatus of 3rd Embodiment is demonstrated. The nondestructive inspection apparatus of the third embodiment is a partial modification of the nondestructive inspection apparatus of the first embodiment, and matters that are not particularly described are the same as those of the nondestructive inspection apparatus of the first embodiment.

  FIG. 6A is an enlarged cross-sectional view of the inspection unit 80 in the nondestructive inspection apparatus of the third embodiment. FIG. 6B is a plane passing through the central axis AX of the portion A1 of FIG. It is the expanded sectional view cut | disconnected along.

As shown in FIG. 6A, the excitation unit 10 has a first semicircular portion 10A that is a first opposing portion and a second semicircular portion 10B that is a second opposing portion, and as a whole It becomes an annular body surrounding the periphery of the heat insulating pipe 1. Note that a connecting member 10j is provided between one opposing ends of the semicircular portions (a pair of opposing portions) 10A and 10B, so that the semicircular portions 10A and 10B can be opened and closed.
In addition, it can be seen that the excitation part 10 is arrange | positioned so that the circumference | surroundings of the heat insulation piping 1 may be covered open partially. That is, the excitation unit 10 has an open cylindrical shape and is disposed so as to partially surround the heat insulating pipe 1. As a result, the lower part of the excitation unit 10 is opened, and a part of the lower surface of the heat insulating pipe 1 is exposed to the outside of the excitation unit 10.

  The first semicircular portion 10A is obtained by winding a coil 10a along the side surface 10s of the semicircular core member 10b. That is, the coil 10a has a pair of arc-shaped portions along the side surface 10s of the core member 10b and a pair of short linear portions along the end surface 10e of the core member 10b. The inner side of the core member 10b is a semicircular magnetic pole portion 10p extending thinly along the circumferential direction.

  As shown in FIG. 6B, a holder 10h for holding the coil 10a can be provided on the side surface 10s of the core member 10b.

  The structure of the second semicircular part 10B is the same as the structure of the first semicircular part 10A, and it is only magnetized in a direction different from the direction of magnetization of the first semicircular part 10A, and the description thereof is omitted. In the second semicircular portion 10B, the inner side of the core member 10b is a semicircular magnetic pole portion 10q extending thinly along the circumferential direction.

  As a result, the pair of magnetic pole portions 10p and 10q are distributed into a pair of semicircular portions (a pair of opposing portions) 10A and 10B, respectively, and continuously extend along the periphery of the heat insulating pipe 1.

The magnetic flux MF0 formed between the central region R1 of the first semicircular part 10A and the central region R1 of the second semicircular part 10B is applied to the heat insulating pipe 1 so as to be substantially orthogonal to the central axis AX of the heat insulating pipe 1. It enters and passes through the pipe body 1a. The magnetic flux MF0 emitted from the pipe main body 1a extends outside the heat insulating pipe 1 so as to be substantially orthogonal to the central axis AX and travels toward the other magnetic pole portion 10q. That is, the exciting unit 10 can generate the magnetic flux MF0 penetrating the pipe body 1a.
The magnetic flux formed between the peripheral region R2 of the first semicircular portion 10A and the peripheral region R2 of the second semicircular portion 10B does not penetrate the pipe body 1a, but sandwiches the magnetic flux MF0 that penetrates the pipe body 1a. Therefore, it has an effect of preventing the magnetic flux MF0 from being dispersed and confining it to the center. That is, the magnetic flux density of the magnetic flux MF0 passing through the pipe body 1a can be increased by the magnetic flux from the peripheral region R2 of the semicircular portions 10A and 10B.

  In FIG. 6A, the magnetic sensor 20 is disposed inside the center of the second semicircular portion 10B. For example, a range close to the boundary between the first semicircular portion 10A and the second semicircular portion 10B, Specifically, the magnetic sensor 20 can be disposed inside the connecting member 10j.

  In addition to the excitation unit 10 and the magnetic sensor 20, the inspection unit 80 includes an annular magnetic shield member 81 that covers them from the surroundings. The magnetic shield member 81 is made of steel or other material having a high magnetic permeability. By covering the excitation unit 10 and the magnetic sensor 20 together with the heat insulating pipe 1 with the magnetic shield member 81, the completion of the local magnetic flux can be avoided and the disturbance can be blocked, so that the defect detection accuracy is improved. be able to.

[Fourth Embodiment]
Hereinafter, the nondestructive inspection apparatus of 4th Embodiment is demonstrated. The nondestructive inspection apparatus of the fourth embodiment is a partial modification of the nondestructive inspection apparatus of the first or third embodiment, and matters not specifically described are the same as the nondestructive inspection apparatus of the first embodiment and the like. It is the same.

  FIG. 7A is an enlarged cross-sectional view of the inspection unit 80 in the nondestructive inspection apparatus of the fourth embodiment, and FIG. 7B is a partially enlarged view of the portion A2 of FIG. It is a perspective view.

  As shown in FIG. 7A, the excitation unit 10 has a first semicircular portion 10A and a second semicircular portion 10B, and is an annular body surrounding the heat insulating pipe 1 as a whole. Note that a connecting member 10j is provided between the opposing ends of the semicircular portions 10A and 10B, so that the semicircular portions 10A and 10B can be opened and closed.

  The first semicircular portion 10A has a core member 10b, and a large number of protrusions are formed as magnetic pole portions 110p inside the core member 10b. Each magnetic pole portion 110p is a columnar protrusion as shown in FIG. 7B, and a coil 110a is wound around the side surface thereof. That is, each magnetic pole part 110p functions as the electromagnet 10E.

  The second semicircular portion 10B also has a core member 10b, and a large number of protrusions are formed as magnetic pole portions 110q inside the core member 10b. Each magnetic pole portion 110q is a columnar protrusion, and a coil 110a is wound around its side surface. That is, each magnetic pole part 110q functions as the electromagnet 10E.

  As a result, the pair of magnetic pole portions 110p and 110q are distributed into a pair of semicircular portions (a pair of opposed portions) 10A and 10B, respectively, and a plurality of the magnetic pole portions 110p and 110q are continuously arranged along the periphery of the heat insulating pipe 1.

The magnetic flux MF0 formed between the central region R1 of the first semicircular portion 10A and the central region R1 of the second semicircular portion 10B is insulated so that it is substantially orthogonal to the central axis AX of the thermally insulated piping 1. 1 enters the pipe body 1a. The magnetic flux MF0 emitted from the pipe main body 1a extends outside the heat insulating pipe 1 so as to be substantially orthogonal to the central axis AX and travels toward the other magnetic pole portion 110q. That is, the exciting unit 10 can generate the magnetic flux MF0 penetrating the pipe body 1a.
The magnetic flux formed between the peripheral region R2 of the first semicircular part 10A and the peripheral region R2 of the second semicircular part 10B does not penetrate the pipe body 1a, but magnetic flux MF0 penetrates the pipe body 1a. And has an effect of preventing the magnetic flux MF0 from being dispersed and confining it at the center. That is, the magnetic flux density of the magnetic flux MF0 passing through the pipe body 1a can be increased by the magnetic flux from the peripheral region R2 of the semicircular portions 10A and 10B.

  In FIG. 7A, the magnetic sensor 20 is disposed inside the center of the second semicircular portion 10B. For example, a range close to the boundary between the first semicircular portion 10A and the second semicircular portion 10B, Specifically, the magnetic sensor 20 can be disposed inside the connecting member 10j.

[Fifth Embodiment]
Hereinafter, the nondestructive inspection apparatus of 5th Embodiment is demonstrated. The nondestructive inspection apparatus of the fifth embodiment is a partial modification of the nondestructive inspection apparatus of the first embodiment, and matters that are not particularly described are the same as those of the nondestructive inspection apparatus of the first embodiment.

  As shown in FIG. 8, in the case of 5th Embodiment, the two test | inspection parts 80 are provided in two places along the center axis AX direction of the heat insulation piping 1. As shown in FIG. That is, the two excitation parts 10 are provided in two places along the central axis AX direction of the heat insulating pipe 1. In this case, the magnetic flux leaking in the direction of the central axis AX of the heat insulating pipe 1 can be reduced, and the magnetic flux penetrating the pipe main body 1a can be easily generated. That is, the magnetic flux emitted from each excitation unit 10 toward the central axis AX tends to spread in the ± Z direction along the central axis AX. However, by arranging the pair of excitation units 10 close to each other, the magnetic flux diverges. And the magnetic flux density of the magnetic flux MF0 penetrating the pipe body 1a can be increased.

[Sixth Embodiment]
Hereinafter, the nondestructive inspection apparatus of 6th Embodiment is demonstrated. The nondestructive inspection apparatus of the sixth embodiment is a partial modification of the nondestructive inspection apparatus of the first or fourth embodiment, and matters not specifically described are the nondestructive inspection of the first or fourth embodiment. It is the same as the device.

  As shown in FIG. 9, in the case of the sixth embodiment, the detection unit 20 </ b> G provided in the inspection unit 80 includes three magnetic sensors 20. The three magnetic sensors 20 are provided at three locations along the radial direction perpendicular to the central axis AX through the central axis AX of the heat insulating pipe 1.

  As shown in FIG. 10, the state of change differs depending on whether the magnetic field detected at the radial position of the heat insulating pipe 1 is caused by a defect in the pipe body 1a or a defect in the exterior plate 1c. Specifically, a magnetic field intensity that is proportional to the strength of the magnetic flux source caused by the defect but attenuates by the reciprocal of the square of the distance from the defect is measured. Therefore, if the magnetic field strength and the inclination of attenuation are known at a specific radial position, the strength of the magnetic flux source (approximately a magnetic dipole) and the distance to the magnetic flux source can be known. That is, the size of the defect corresponding to the magnetic flux source and the distance to the defect can be estimated. The slope of the attenuation of the magnetic field strength can be thought of as the difference in magnetic field strength at multiple positions in the radial direction, so detecting a change in magnetic field strength at multiple positions in the radial direction is equivalent to a magnetic flux source for the same reason. It is possible to estimate the size of the defect and the distance to the defect.

  In the case of the present embodiment, the magnetic field or magnetic field strength at these positions is measured by the three magnetic sensors 20. At this time, fitting is performed to approximate the magnetic field strength at two or more observation points by a curve having a reciprocal of the square of the distance from the pipe body 1a and a curve having a reciprocal of the square of the distance from the exterior plate 1c. . For the approximation, for example, a least square method can be used. As a result, the fitting result with the smaller sum of squares can be made appropriate, and it can be clearly determined whether the defect exists in the pipe body 1a or the exterior plate 1c. The arithmetic processing as described above is performed by the control unit 70 of FIG.

  In the above, the number of magnetic sensors 20 constituting the detection unit 20G is not limited to three, and can be two or four or more. It is desirable that the magnetic sensors 20 be arranged as far as possible from each other within a range close to the heat insulating pipe 1.

  In the example shown in FIG. 9, the magnetic sensor 20 is disposed between the first semicircular part 10A and the second semicircular part 10B. This is because a parallel magnetic field extending in the circumferential direction is formed in this region, and the direct influence from the pair of semicircular portions 10A and 10B can be substantially offset. That is, if only the magnetic field strength or magnetic field strength in the radial direction or the Y direction is detected by the magnetic sensor 20, only the magnetic field strength caused by the defect can be extracted to increase the S / N ratio. However, by obtaining in advance the output value of the magnetic sensor 20 when there is no defect as a reference value, and by subtracting the reference value from the detection value or measurement value that may have a defect, In the case of extracting only the turbulence component of the magnetic field due to the defect, it is less necessary to consider the above arrangement.

[Seventh Embodiment]
Hereinafter, the nondestructive inspection apparatus of 7th Embodiment is demonstrated. The nondestructive inspection apparatus of the seventh embodiment is a partial modification of the nondestructive inspection apparatus of the first embodiment, and matters that are not particularly described are the same as those of the nondestructive inspection apparatus of the first embodiment.

As shown in FIG. 11, in the case of the seventh embodiment, the detection unit 20 </ b> G provided in the inspection unit 80 includes three magnetic sensors 20. The three magnetic sensors 20 are provided at three places where the positions of the heat insulating pipe 1 in the direction of the central axis AX are different. Specifically, the three magnetic sensors 20 are arranged at equal intervals in the Z direction in the vicinity of the outer peripheral side surface 1 s of the heat insulating pipe 1. In this case, magnetic fluxes at a plurality of positions in the central axis AX direction of the heat insulating pipe 1 can be detected, and more various inspections are possible. Specifically, it is possible to perform processing such as axial differentiation to emphasize the change in the magnetic flux in the axial direction, and to judge a scratch when the difference exceeds a threshold value compared with a normal tube without a defect.
〔Concrete example〕

  Hereinafter, specific examples will be described. As the excitation unit of Example 1, the excitation unit 10 (see FIG. 6A) incorporated in the apparatus of the third embodiment was used. In addition, a remote pulse type excitation unit was used as Comparative Example 1, and an eddy current flaw detection type excitation unit was used as Comparative Example 2. A simulation was performed on the first specific example and the first and second comparative examples with respect to the heat insulating pipe 1 having an outer diameter of 265 mm. In addition, although illustration is abbreviate | omitted, the comparative example 1 arrange | positions a pair of coils similar to a Helmholtz type so that the heat insulation piping 1 may be passed through the center, and was mutually spaced apart in the center axis AX direction. In Comparative Example 2, a small-diameter coil is placed close to the side surface of the heat insulating pipe 1 so that the normal of the side surface is the axis of the coil.

表１において、上段が具体例１に対応し、中段が比較例１に対応し、下段が比較例２に対応する。具体例１の上段において、「配管傷−正常」は、配管本体に欠陥がある場合であって、欠陥のない正常な断熱配管との差をとった信号値（磁場強度）を示し、「外管傷−正常」は、外装板に欠陥がある場合であって、欠陥のない正常な断熱配管との差をとった信号値を示し、「両管傷−正常」は、配管本体及び外装板に欠陥がある場合であって、欠陥のない正常な断熱配管との差をとった信号値を示し、「（配管傷−正常）／（外管傷−正常）〔％〕」は、上記配管本体に欠陥がある場合の信号値を外装板に欠陥がある場合の信号値で割った比を％で表示したものである。各項目の右側のうち半径方向は、断熱配管の半径方向の磁場成分を意味し、回転方向は、断熱配管の周方向の磁場成分を意味し、軸方向は、断熱配管の中心軸方向の磁場成分を意味する。半径方向の磁場成分は、配管本体を貫くような磁束を発生させる場合に検出信号を高くできると考えられる。 In the case of the specific example 1, the inner diameter of the coil is set to 305 mm, the inner width in the coil axis direction is set to 40 mm, and the position of the magnetic sensor is a coordinate in which the Z axis is arranged on the center axis AX with respect to the center axis AX of the heat insulating pipe 1. (152.5, 0, 0), and the position of the defect is on the Y direction side of the central axis AX. That is, the position of the magnetic sensor is similar to that shown in FIG. 6A, and the positions of the defects are at positions d1 and d2 in FIG. 6A. In the case of Comparative Example 1, the inner diameter of the pair of coils is set to 305 mm, the distance between the pair of coils is set to 400 mm, and the position of the magnetic sensor is represented by coordinates (0, 152.5, 0) with reference to the central axis AX of the heat insulating pipe 1. And an intermediate position between the coils on the Y direction side of the central axis AX. The position of the defect was the same as in specific example 1. In the case of Comparative Example 2, the inner diameter of the coil is set to 120 mm, the distance between the coil and the outer plate is set to 19.7 mm, and the position of the magnetic sensor is expressed by coordinates (0, 152.5, 0) and on the Y direction side of the central axis AX. The position of the defect was the same as in specific example 1.
The results are summarized in Table 1 below.
[Table 1]

In Table 1, the upper stage corresponds to Specific Example 1, the middle stage corresponds to Comparative Example 1, and the lower stage corresponds to Comparative Example 2. In the upper part of specific example 1, “pipe flaw-normal” indicates a signal value (magnetic field strength) obtained by taking a difference from normal heat-insulated pipe having no defect when the pipe body is defective. “Tube damage-normal” indicates a signal value obtained by taking a difference from normal heat-insulated piping having no defect when the exterior plate has a defect. Indicates a signal value obtained by taking a difference from normal heat-insulated piping having no defect, and “(piping flaw-normal) / (outer pipe flaw-normal) [%]” indicates the above-mentioned piping. The ratio obtained by dividing the signal value when there is a defect in the main body by the signal value when there is a defect in the exterior plate is displayed in%. The radial direction in the right side of each item means the magnetic field component in the radial direction of the heat insulation pipe, the rotation direction means the magnetic field component in the circumferential direction of the heat insulation pipe, and the axial direction is the magnetic field in the central axis direction of the heat insulation pipe. Means ingredients. It is considered that the magnetic field component in the radial direction can increase the detection signal when generating a magnetic flux that penetrates the pipe body.

  Summarizing the results, it can be said that the ratio of (pipe damage−normal) / (outer tube damage−normal) and the like are larger in the order of specific example 1, comparative example 1, and comparative example 2. That is, it is considered that it becomes relatively easy to distinguish the defect of the pipe body from the defect of the exterior plate by using the method of the specific example 1.

  Although the nondestructive inspection apparatus according to the embodiment has been described above, the nondestructive inspection apparatus according to the present invention is not limited to the above example. For example, the calculation method and the threshold value for determining the presence / absence of a pipe defect signal can be appropriately set according to the environment.

  DESCRIPTION OF SYMBOLS 1 ... Heat insulation piping, 1a ... Piping main body, 1b ... Heat insulation material, 1c ... Exterior board, 1s ... Outer peripheral side surface, 10 ... Excitation part, 10A, 10B ... Semicircle part, 10E ... Electromagnet, 10a ... Coil, 10b ... Core member 10p, 10q ... magnetic pole part, 11a ... main body part, 11b, 11b ... yoke part, 11p, 11q ... magnetic pole part, 12a ... end part, 12a, 12b ... end part, 20 ... magnetic sensor, 40 ... pulse power supply, 50 DESCRIPTION OF SYMBOLS ... Magnetic sensor circuit 60 ... Movement mechanism, 70 ... Control part, 75 ... Main control part, 80 ... Inspection part, 81 ... Magnetic shield member, 100 ... Non-destructive inspection device, 110a ... Coil, 110p, 110q ... Magnetic pole part, AX ... central axis, R1 ... central region, R2 ... peripheral region

Claims (12)

An excitation unit that enters the heat insulation pipe substantially perpendicular to the central axis of the heat insulation pipe and generates a magnetic flux penetrating the pipe body of the heat insulation pipe;
A magnetic sensor for detecting a magnetic signal generated by thinning of the pipe body;
A signal processing unit for computing the detection output of the magnetic sensor;
A nondestructive inspection apparatus comprising:   The non-destructive inspection apparatus according to claim 1, wherein the excitation unit is disposed so as to cover a part of the heat insulating pipe while being partially opened. The excitation unit has a coil for passing a current and a core member for guiding a magnetic flux formed by the coil,
The non-destructive inspection apparatus according to claim 1, wherein the core member has a pair of magnetic pole portions arranged so as to sandwich the heat insulating pipe.   4. The non-magnetic coil according to claim 3, wherein a pulsed excitation current is supplied to the coil, and the signal processing unit analyzes a detection output of the magnetic sensor in synchronization with the excitation current. Destructive inspection equipment.   The non-destructive inspection apparatus according to claim 3, wherein the excitation unit extends in an arc shape along the periphery of the heat insulating pipe.   The said core member is extended in the semicircle shape along the circumference | surroundings of the said heat insulation piping, The said pair of magnetic pole part is formed in a pair of edge part of the said core member, The Claim 6 characterized by the above-mentioned. Nondestructive inspection equipment.   The core member is composed of a pair of semicircular facing portions arranged with the heat insulating piping interposed therebetween, and the pair of magnetic pole portions are distributed to the pair of facing portions, respectively, along the periphery of the heat insulating piping. The non-destructive inspection apparatus according to claim 5, wherein the non-destructive inspection apparatus extends continuously or is continuously arranged.   The non-destructive inspection apparatus according to claim 1, wherein the excitation unit is provided in proximity to a plurality of locations along a central axis direction of the heat insulating pipe.   The said magnetic sensor is provided in the multiple places along the radial direction perpendicular | vertical to the said central axis through the central axis of the said heat insulation piping, The nondestructive as described in any one of Claims 1-8 characterized by the above-mentioned. Inspection device.   10. The nondestructive inspection apparatus according to claim 1, wherein the magnetic sensor is provided at a plurality of locations having different positions in the central axis direction of the heat insulating pipe.   The non-destructive inspection apparatus according to claim 1, wherein the excitation unit and the magnetic sensor are covered with a magnetic shield member together with the heat insulating pipe.   The moving part which makes the said excitation part rotatable along the periphery of the said heat insulation piping, and enables the said excitation part to move along the center axis direction of the said heat insulation piping is further provided. The nondestructive inspection apparatus according to any one of 11.

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