JP2016173340A - Pipeline inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipeline inspection device capable of integrating pipeline defect signals within a wide range of a heat insulation pipeline in a short time and with high accuracy.SOLUTION: A pipeline inspection device includes an exciting coil 10 configured to impart magnetism to a heat insulation pipeline 1, and a plurality of magnetic sensors 20 arranged around the exciting coil 10. At a position of each magnetic sensor 20, a wide range of magnetic data indicating a magnetic amount and magnetic direction generated by the exciting coil 10 is integrated and detected. By executing arithmetic processing to the magnetic data of an inspected portion detected by the magnetic sensor 20 with a reference data group formed by collecting reference data on the premise of a standard heat insulation pipeline, the detection inspection device separates a coil exciting signal resulting from the exciting coil 10 from a pipeline defect signal, and integrates and detects pipeline defect signals within a wide range of the heat insulation pipeline 1 in a short time and with high accuracy.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pipe inspection apparatus for inspecting defects of heat insulation pipes non-destructively by magnetism.

  As a method for inspecting defects in heat insulation piping by magnetism, for example, there is a method for inspecting by a nondestructive inspection apparatus using pulse magnetism (remote pulse method) (see Patent Document 1). Specifically, the apparatus of Patent Document 1 is configured to generate a magnetic field for detection by winding a coil around the outer peripheral surface of a heat insulating pipe. Further, the apparatus of Patent Document 1 maps defect (thinning) inspection results obtained by arraying magnetic sensors and analyzing pulse intensity and signal time attenuation in the output signals of the magnetic sensors.

  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. There is a method (eddy current flaw detection method) to inspect by (see Patent Document 2).

  In the devices used in Patent Documents 1 and 2, a large number of sensors are arranged to avoid or reduce the magnetization of the piping and the exterior plate of the piping due to excitation, and to shorten the measurement time. Depends on the distance between the excitation coil and the sensor and the position and physical properties of the magnetic material between the excitation coil and the sensor, for example, it tends to be detected with different values near and far from the excitation coil. Without considering the arrangement, it is not easy to improve the reproducibility of the measurement result.

JP 2014-44087 A JP-A-8-2013347

  An object of this invention is to provide the piping inspection apparatus which can obtain a piping defect signal collectively in a short time and with high precision in the wide range of heat insulation piping.

  In order to solve the above problems, a pipe inspection apparatus according to the present invention includes an exciting coil that gives magnetism to a heat insulating pipe, and a plurality of magnetic sensors arranged around the exciting coil, and at the position of each magnetic sensor, The amount of magnetism generated by the exciting coil and the direction of the magnetism are acquired as reference data based on standard heat insulation piping, and from the reference data and magnetic data obtained by detecting the heat insulation piping to be inspected with a magnetic sensor. A pipe defect signal representing the thinning of the insulated pipe is obtained. Here, the standard heat insulation piping means thinning, that is, piping having no defect.

  In the above piping inspection device, a weak change depending on the spatial position appears in the magnetic data detected by a plurality of magnetic sensors, but reference data that assumes standard heat insulation piping is acquired, and this reference data is used. By removing the signal component corresponding to the case where there is no thinning, that is, no defect, depending on the spatial position of the magnetic data from the magnetic data detected by a plurality of magnetic sensors, the pipe defect signal is increased in a short time and in a wide area of the insulated pipe. Can be obtained collectively with accuracy. The reference data may be acquired in advance before the inspection, or may be acquired before extracting the pipe defect signal from the magnetic data.

  In a specific aspect or aspect of the present invention, in the pipe inspection apparatus, the reference data is calculated by a simulation that takes into account the installation state of the heat insulation pipe to be inspected, the exterior plate of the heat insulation pipe, the excitation coil, and the magnetic sensor. To do. In this case, by using the reference data based on the simulation, it is possible to flexibly cope with measurement of various heat insulating pipes.

  In another aspect of the present invention, the reference data corresponds to the insulated pipe to be inspected, but is obtained by measuring in advance the value of a normal pipe that is not thinned. In this case, an accurate piping defect signal can be easily obtained by referring to normal piping data that has been measured and stored in advance.

  In still another aspect of the present invention, the reference data is obtained by measuring in real time a part of the magnetic data of the insulated pipe to be inspected. In this case, it is possible to calibrate the magnetic data of the heat insulation pipe to be inspected in real time. In addition, it is not necessary to prepare reference data in advance before inspection, and it is not necessary to identify the type of insulated piping or the configuration of the piping inspection device, so it is easier to generate reference data and improve the convenience of piping inspection. be able to.

  In still another aspect of the present invention, the reference data measures at least a part of the magnetic data in the region of 60 ° to 240 ° below the heat insulating pipe, with the uppermost apex of the heat insulating pipe to be inspected as a reference. By getting. Here, the angle of the region is considered clockwise with the most apex as a reference. In this case, the reference data can be more easily generated by measuring the magnetic data in the lower 60 ° to 240 ° region of the heat-insulating pipe that tends to have relatively little thinning.

  In yet another aspect of the present invention, a pipe defect signal is obtained by integrating the reciprocal of the reference data to the magnetic data.

  In still another aspect of the present invention, a pipe defect signal is obtained by subtracting reference data from magnetic data.

  In still another aspect of the present invention, the exciting coil is disposed along the circumference of the heat insulating pipe.

  In still another aspect of the present invention, the magnetic sensors are provided at a plurality of locations along the circumference of the cross-sectional pipe.

  In still another aspect of the present invention, the magnetic sensor is provided at a plurality of locations along the central axis direction of the cross-sectional pipe.

It is a conceptual diagram explaining the piping inspection apparatus of 1st Embodiment. (A) is the figure which expand | deployed the test | inspection part among the piping test | inspection apparatuses of FIG. 1, (B) is a side view of the state which wound the test | inspection part around the heat insulation piping, (C) is (B) FIG. It is a block diagram explaining the basic composition of a control part among piping inspection devices of Drawing 1. (A)-(D) is a figure explaining the principle of a piping test | inspection, (A) and (B) are the magnetic field diagram and magnetic flux density distribution figure in a normal part, respectively (C) and (D) These are a magnetic force line figure and magnetic flux density distribution figure in a defective part, respectively. It is the figure which combined FIG. 4 (B) and 4 (D). (A) And (B) is a figure explaining the data handled by the test | inspection using the piping inspection apparatus of FIG. 1, (A) is a figure explaining the reciprocal number of reference | standard data, (B) It is a figure explaining correction data. It is a flowchart explaining the piping inspection method in 1st Embodiment. (A) And (B) is a figure explaining the data handled by the test | inspection using the piping inspection apparatus of 2nd Embodiment, (A) is a figure explaining reference | standard data, (B) It is a figure explaining correction data. It is a flowchart explaining the piping inspection method in 2nd Embodiment. (A) is the figure which expand | deployed the test | inspection part among the piping test | inspection apparatuses of 3rd Embodiment, (B) is a side view of the state which wound the test | inspection part. It is a flowchart explaining the piping inspection method in 3rd Embodiment. It is the figure which expand | deployed the test | inspection part among the piping test | inspection apparatuses of 4th Embodiment.

[First Embodiment]
The pipe inspection apparatus 100 shown in FIG. 1 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 the thinning that is a defect of the heat insulation pipe 1. It is to be inspected. Here, the thinning of the heat insulating pipe 1 means deterioration of the pipe such as corrosion, fatigue, and cracks.

  As shown in FIG. 2 (C), the heat insulation pipe 1 to be inspected is an steel pipe 1a, a heat insulating material 1b covering the periphery of the pipe 1a, and an exterior plate 1c covering the heat insulating material 1b. Have That is, the heat insulating pipe 1 has a triple pipe structure in which the pipe 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 1a.

  The pipe inspection apparatus 100 includes an exciting coil 10, a plurality of magnetic sensors 20, an inspection base 30, a pulse power supply 40, a magnetic sensor circuit 50, a moving mechanism 60, and a control unit 70. In the pipe inspection apparatus 100, the excitation coil 10, the magnetic sensor 20, and the inspection base 30 function as an inspection unit 80. The inspection unit 80 is movable on the outer peripheral surface of the heat insulating pipe 1, and detects the magnetic field generated by the excitation coil 10 in the presence of the heat insulating pipe 1 by the magnetic sensor 20.

  The exciting coil 10 generates a pulse magnetic field. The exciting coil 10 includes a pair of a first coil 10a and a second coil 10b, and is provided on the inspection base 30 with a predetermined interval in the direction of the central axis AX. The exciting coil 10 is supported by the inspection base 30 and can be arranged at an arbitrary position along the circumference of the heat insulating pipe 1 by the operation of the moving mechanism 60. The direction of the current in the first and second coils 10a and 10b may be the same or opposite. Further, a current may be passed through only one of the first and second coils 10a and 10b.

  The magnetic sensor 20 detects, for example, a magnetic field parallel to the central axis AX direction of the heat insulating pipe 1. Thereby, the magnetic sensor 20 can detect the change of the magnetic field transmitted through the heat insulating pipe 1. Since the pipe inspection apparatus 100 is provided with a plurality of magnetic sensors 20, it can detect magnetic data in a wide range collectively. The magnetic sensor 20 is provided on the inspection base 30 and between the pair of coils 10a and 10b. The magnetic sensor 20 is supported by the inspection base 30 and is arranged in an array along the outer peripheral surface of the heat insulating pipe 1. As the magnetic sensor 20, for example, a TMR sensor, an AMR sensor, or the like is used. The number of the magnetic sensors 20 may be two or more, and the number can be changed as appropriate according to the application. In the example of FIG. 1, as shown in FIGS. 2A and 2B, three magnetic sensors 20 are provided along the long side of the inspection base 30 on the center side in the circumferential direction of the inspection base 30. When the heat insulation pipe 1 is covered with the inspection base 30, the heat insulation pipe 1 is positioned above the heat insulation pipe 1. More specifically, the three magnetic sensors 20 are arranged within a range of ± 60 ° on the upper side of the heat insulating pipe 1 with respect to the topmost OS on the upper side of the heat insulating pipe 1 when viewed from the cross-sectional direction of the heat insulating pipe 1. Has been.

  As already described, the inspection base 30 supports the exciting coil 10 and the magnetic sensor 20 so as to be arranged at predetermined positions. The inspection base 30 is a sheet-like member and is detachably attached so as to cover the periphery of the heat insulating pipe 1. As shown in FIG. 2 (A), the inspection base 30 can be deployed, and as shown in FIG. 2 (B), the inspection base 30 is deformed so as to be wound along the shape of the heat insulating pipe 1 to be inspected. It is possible. The magnitude | size of the test | inspection base 30 can be changed suitably according to a use, and the whole heat insulation piping 1 may be covered so that the heat insulation piping 1 may be penetrated, and a part of heat insulation piping 1 may be covered. . The inspection base 30 can be moved along the central axis AX of the heat insulation pipe 1 by the operation of the moving mechanism 60. For example, after the measurement of the part to be inspected with the heat insulation pipe 1 covered with the inspection base 30 is performed, It is possible to repeat the operation of moving the inspection site while maintaining the state.

  The pulse power supply 40 applies a pulse voltage to at least one of the pair of exciting coils 10. The pulse power supply 40 outputs a square wave and drives the exciting coil 10 with a predetermined frequency and duty ratio. The pulse power supply 40 can appropriately change the direction of the current flowing through the first and second coils 10a and 10b. For example, if the current directions of the first and second coils 10a and 10b are driven to be the same, a pulsed magnetic field in the same direction is generated in the heat insulating pipe 1, and the detected signal intensity is increased.

  The magnetic sensor circuit 50 drives the magnetic sensor 20 and measures a magnetic field. The magnetic sensor circuit 50 measures the amount of magnetism (magnetic field strength) in the desired direction of magnetism generated by the exciting coil 10.

  The moving mechanism 60 moves the inspection unit 80 along the outer peripheral surface 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 supply 40, the magnetic sensor circuit 50, and the like to drive the excitation coil 10 and the magnetic sensor 20 to perform the detection operation. In addition, the control unit 70 operates the moving mechanism 60 to move the inspection base 30. Further, the control unit 70 analyzes the response of the pulse magnetic field detected by 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 by 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 stores a program for operating the control unit 70, magnetic data detected by the magnetic sensor 20, a reference data group that collects reference data based on standard adiabatic piping, and the like. The reference data is data on the amount of magnetism generated by the exciting coil 10 and the direction of the magnetism, and is stored for each position of each magnetic sensor 20. The reference data is calculated by simulation considering the installation state of the heat insulation pipe 1 to be inspected, the exterior plate 1c of the heat insulation pipe 1, the excitation coil 10, and the magnetic sensor 20. Although the simulation can be performed in advance and only the result can be stored in the storage unit 73, the simulation can also be performed at the inspection site by inputting condition parameters.

  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, the principle of the pipe inspection will be described.
4 (A) and 4 (C) illustrate magnetic flux lines around the heat insulating pipe 1. FIG. 4A is a magnetic force diagram when the thickness is thin, that is, when there is no defect (a pipe having only a normal portion), and FIG. 4C is when the thickness is reduced, that is, when there is a defect (a pipe having a thickness reduction portion). It is a magnetic field diagram. As shown in FIGS. 4 (A) and 4 (C), the lines of magnetic force are very strong around the exciting coil 10. In this case, in addition to the leakage magnetic flux signal due to the defect, the magnetic flux density caused by the exciting coil 10 is detected as a signal superimposed on the magnetic sensor 20 disposed on the broken lines M1 and M2 in the drawing.

  FIG. 4B shows the magnetic flux density distribution of the heat insulating pipe 1 of only the normal part in the cross section indicated by the broken line M1 in FIG. FIG. 4D shows a magnetic flux density distribution of the heat insulating pipe 1 having a thinned portion in a cross section indicated by a broken line M2 in FIG. Here, the direction of the magnetic flux density has components in two directions, and signals of both components are plotted as an example. For simplicity, the third Z-direction component is not considered at this time. 4B and 4D, the solid line L1 is a component in the X direction, and the solid line L2 is a component in the Y direction. As shown in FIGS. 4B and 4D, the reception signal of the magnetic sensor 20 is large in the vicinity of the excitation coil 10 due to the influence of the excitation coil 10 in both the X component and the Y component. As shown in FIG. 5, when the magnetic flux density distributions shown in FIGS. 4 (B) and 4 (D) are combined, the magnetic flux density distribution is substantially the same in the heat insulating pipe 1 having only the normal portion and the heat insulating pipe 1 having the reduced thickness portion. Overlap. That is, the pipe defect signal resulting from the thinning of the heat insulating pipe 1, that is, the defect is very small and is buried in the reception signal (coil excitation signal) caused by the excitation coil 10, and is difficult to detect well. In this way, a slight change depending on the spatial position appears in the magnetic data detected by the plurality of magnetic sensors 20, but since there is almost no difference in the detection signal depending on the presence or absence of the thinned portion, it is detected by the magnetic sensor 20. It is difficult to use the magnetic data as it is for determining the presence or absence of a pipe defect signal.

  From the above, it is necessary to remove the influence of the exciting coil 10 from the magnetic data detected by the magnetic sensor 20. The pipe inspection apparatus 100 shown in FIG. 1 previously acquires, as reference data, the amount and direction of magnetism generated by the exciting coil 10 for each position of the magnetic sensor 20, and the reference data and the magnetic sensor 20 detect the reference data. A pipe defect signal is obtained from magnetic data.

  In the present embodiment, the reference data is acquired by obtaining a magnetic flux density distribution by simulation. As already described, the reference data is calculated in consideration of the installation state of the heat insulation pipe to be inspected, the exterior plate of the heat insulation pipe, the excitation coil, and the magnetic sensor. Then, calibration is performed by integrating the reciprocal of the magnetic flux density distribution result (reference data) of the heat insulation pipe (normal pipe) of only the normal part to the output value (magnetic data) of the magnetic sensor 20, and correction data is obtained. calculate. In the case where the heat insulating pipe 1 has a thinned portion at the inspection site, the correction data includes a pipe defect signal. That is, by performing the above calculation, the pipe defect signal can be separated and extracted from the magnetic data detected by the magnetic sensor 20. By using the reference data based on the simulation as described above, it is possible to flexibly cope with the measurement of various heat insulating pipes 1.

  Hereinafter, in the present embodiment, an example of signal processing in a certain direction at the time of calibration, specifically, in the X direction or the Y direction will be described. The signal component used for signal processing may be either the X direction or the Y direction, and may be other components other than the X direction and the Y direction. In this embodiment, when the reciprocal number of the normal piping signal (reference data) shown in FIG. 6 (A) is added to the magnetic data shown in FIG. 4 (D), as correction data as shown in FIG. 6 (B), A pipe defect signal separated from the reception signal of the magnetic sensor 20 is obtained. Regarding the presence or absence of a defect, the correction data is compared with a predetermined threshold, and if the threshold is exceeded, it is determined that a defect exists.

Hereinafter, a pipe inspection method using the pipe 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, information about the installation state of the heat insulation pipe 1 to be inspected, the exterior plate of the heat insulation pipe 1, the excitation coil, and the magnetic sensor is input as the condition parameter of the inspection target by the input unit 72 of the control unit 70. (Step S12).

  Next, reference data corresponding to the heat insulating pipe 1 is acquired and stored (step S13). As already described, in this embodiment, reference data is obtained by simulation. Specifically, based on the condition parameters input in step S12, it is standard that the insulated pipe 1 to be inspected is a normal pipe using a program stored in the storage unit 73 of the control unit 70. In this case, the amount of magnetism in the desired magnetic direction (specifically, the magnetic field strength in the X direction or Y direction) generated at the position of the magnetic sensor 20 by the exciting coil 10 in this case is calculated, and the reference data Get. The obtained reference data is stored in the storage unit 73. The reference data is calculated for each magnetic sensor 20 and stored as a reference data group. Step S11 and steps S12 and S13 may be performed in reverse order. Further, steps S12 and S13 may be performed in advance before the inspection, the reference data may be stored, steps S12 and S13 may be omitted during the inspection, and step S14 to be described later may be performed after step S11.

  Next, the magnetic data of the heat insulation piping 1 are acquired and preserve | saved (step S14). The control unit 70 operates the pulse power supply 40 to apply a pulse voltage to the exciting coil 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 exciting coil 10 is detected by the magnetic sensor 20. Here, the amount of magnetism in the desired magnetism direction detected by the magnetic sensor 20 is the magnetic field strength (for example, 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, correction data is acquired using the reference data obtained in step S13 and the magnetic data obtained in step S14 (step S15). In the main control unit 75 of the control unit 70, the reference data and the magnetic data are read from the storage unit 73, and the reciprocal of the reference data and the magnetic data are integrated to perform calibration. Thus, correction data obtained by removing the reception signal (coil excitation signal) caused by the excitation coil 10 from the magnetic data is obtained. When there is a thinned portion at the inspection site, a pipe defect signal appears in the correction data.

  Next, it is determined whether or not a piping defect signal is included in the correction data obtained in step S15 (step S16). When the correction data includes a pipe defect signal that is equal to or greater than a predetermined threshold (Y in step S16), it is determined that a thinned portion exists in the heat insulating pipe 1, and the storage unit 73 together with the position information of the heat insulating pipe 1 indicates that there is a thinned portion. And the corresponding part is displayed on the display unit 71 (step S17). If the correction data does not include a pipe defect signal equal to or greater than a predetermined threshold value (N in step S16), 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 S18).

  In the above, the processes of steps S14 to S18 are performed on the magnetic data detected by each magnetic sensor 20 of the pipe inspection apparatus 100, but the processes may be performed simultaneously or sequentially. Good. As described above, the magnetic data can be collectively detected by the plurality of magnetic sensors 20, and the pipe defect signal can be collectively detected in the wide range of the heat insulating pipe 1.

  Next, when another part of the heat insulating pipe 1 is continuously inspected (Y in step S19), the control unit 70 operates the moving mechanism 60 to move the inspection part 80 to the next inspected part (step S20). , Steps S14 to S18 are repeated. When the inspection of another part of the heat insulating pipe 1 is not performed (N in step S19), the inspection is terminated.

  In the pipe inspection apparatus described above, a slight change depending on the spatial position appears in the magnetic data detected by the plurality of magnetic sensors 20, but reference data based on standard adiabatic piping is acquired. By removing the signal component corresponding to the case where there is no defect depending on the spatial position of the magnetic data from the magnetic data detected by the plurality of magnetic sensors 20 using the sensor, a pipe defect signal is generated in a wide range of the heat insulating pipe 1 for a short time. In addition, it can be obtained collectively with high accuracy.

[Second Embodiment]
Hereinafter, the pipe inspection apparatus according to the second embodiment will be described. The pipe inspection apparatus of the second embodiment is a partial modification of the pipe inspection apparatus of the first embodiment, and matters not specifically described are the same as those of the pipe inspection apparatus of the first embodiment.

  In the present embodiment, the reference data corresponds to the heat insulating pipe 1 to be inspected, but is obtained by measuring in advance the value of a normal pipe that is not thinned. Thereby, an accurate piping defect signal can be easily obtained by referring to data of normal piping stored in advance. The value of the normal pipe is, for example, a heat insulation pipe that does not have a thinned portion as a sample of a standard heat insulation pipe, and the amount of magnetism generated by the exciting coil 10 and the direction of magnetism are determined for each position of the magnetic sensor 20. Obtain by measuring. The obtained reference data is stored in the storage unit 73 of the control unit 70, and data corresponding to the adiabatic pipe 1 to be inspected is read out at the time of inspection.

  Hereinafter, an example of signal processing in a certain direction, specifically, the X direction or the Y direction at the time of calibration according to the present embodiment will be described. The signal component used for signal processing may be either the X direction or the Y direction, and may be other components other than the X direction and the Y direction. In the present embodiment, when the normal piping signal shown in FIG. 8A is subtracted from the magnetic data shown in FIG. 4D, the received signal of the magnetic sensor 20 is obtained as correction data as shown in FIG. 8B. A pipe defect signal separated from the above is obtained.

Hereinafter, a pipe inspection method using the pipe inspection apparatus 100 of the present embodiment 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), and then the magnetic data of the heat insulating pipe 1 is acquired and stored (step S14).

  Next, correction data is acquired using the reference data stored in advance in the storage unit 73 of the control unit 70 and the magnetic data obtained in step S14 (step S215). In the main control unit 75 of the control unit 70, the reference data and magnetic data are read from the storage unit 73, and calibration is performed by subtracting the reference data from the magnetic data. Thus, correction data obtained by removing the reception signal (coil excitation signal) caused by the excitation coil 10 from the magnetic data is obtained. When there is a thinned portion at the inspection site, a pipe defect signal equal to or greater than a predetermined threshold appears in the correction data.

  Next, it is determined whether or not a pipe defect signal is included in the correction data obtained in step S215 (step S16), and processing according to the presence or absence of the pipe defect signal is performed (steps S17 and S18). Thereafter, similarly to the first embodiment, the processes after step S19 are performed.

  In the present embodiment, the correction data is obtained by subtracting the reference data from the magnetic data at the time of calibration in step S15. However, as in the first embodiment, the correction data is obtained by integrating the reciprocal of the reference data to the magnetic data. You may get

[Third Embodiment]
Hereinafter, the pipe inspection apparatus according to the third embodiment will be described. The piping inspection device of the third embodiment is a partial modification of the piping inspection device of the first embodiment, and matters that are not particularly described are the same as those of the piping inspection device of the first embodiment.

  As shown in FIGS. 10A and 10B, the magnetic sensor 20 is provided on the inspection base 30 and between the pair of coils 10a and 10b. The magnetic sensor 20 is supported by the inspection base 30 and is arranged in an array along the outer peripheral surface of the heat insulating pipe 1. In the example of FIGS. 10A and 10B, eight magnetic sensors 20 are provided along the long side of the inspection base 30 on the center side in the circumferential direction of the inspection base 30. Are covered with the test base 30 at substantially equal intervals around the entire circumference of the heat insulating pipe 1.

  In the present embodiment, the reference data measures at least a part of magnetic data in a region of 60 ° to 240 ° below the heat insulating pipe 1 with reference to the uppermost vertex OS on the upper side of the heat insulating pipe 1 to be inspected. By getting. Here, the angle of the region is considered clockwise with the most vertex OS as a reference. The heat insulating pipe 1 tends to be thinned in the range of the upper side ± 60 ° in many cases, and the possibility of thinning is low in the remaining lower side of 60 ° to 240 °. Therefore, the magnetic sensors 20 are arranged so as to surround the entire circumference in the circumferential direction, and the magnetic data in the range of ± 60 ° on the upper side of the heat insulating pipe 1 and the magnetic data in the range of 60 ° to 240 ° on the lower side are combined. By measuring, the lower magnetic data can be used as reference data. Thereby, some magnetic data of the heat insulation piping 1 made into a test object can be measured in real time, and the magnetic data of the heat insulation piping 1 can be calibrated in real time. In addition, it is not necessary to prepare reference data in advance before inspection, and it is not necessary to identify the type of the heat insulating pipe 1 or the configuration of the pipe inspection apparatus 100. Therefore, the reference data can be generated more easily and the convenience of the pipe inspection can be achieved. Can be increased.

Hereinafter, a pipe inspection method using the pipe inspection apparatus 100 of the present embodiment 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), and then the magnetic data of the heat insulating pipe 1 is acquired and stored (step S14). In the present embodiment, in step S14, magnetic data of all the magnetic sensors 20 provided in the pipe inspection device 100 is acquired.

  Next, reference data corresponding to the heat insulating pipe 1 is acquired and stored (step S313). In this embodiment, reference data is obtained by distributing specific data from the magnetic data obtained in step S14. Specifically, reference data is obtained using magnetic data in the range of 60 ° to 240 ° below the heat insulating pipe 1 among the magnetic data obtained in step S14. The reference data is obtained by calculating from the average of the lower magnetic data, for example.

  Next, correction data is acquired using the reference data obtained in step S313 and the magnetic data obtained in step S14 (step S15). In the present embodiment, at the time of calibration, correction data may be obtained by integrating the reciprocal of the reference data with the magnetic data as in the first embodiment, or the reference data is obtained from the magnetic data as in the second embodiment. Correction data may be obtained by subtracting.

  Next, it is determined whether or not a pipe defect signal is included in the correction data obtained in step S15 (step S16), and processing corresponding to the presence or absence of the pipe defect signal is performed (steps S17 and S18). Thereafter, similarly to the first embodiment, the processes after step S19 are performed.

In the present embodiment, it is also possible to determine whether or not a pipe defect signal (abnormal value) is included in the magnetic data by a process different from steps S313 and S15 described above. Hereinafter, an example of a method for extracting an abnormal value will be described. The average value A is obtained by using the data of the lower magnetic sensors 20a, 20b, 20c, 20d, and 20e (referred to as data D1, D2, D3, D4, and D5, respectively) with less abnormality due to the thinning of the heat insulating pipe 1. And the following formula.
A = (D1 + D2 + D3 + D4 + D5) / 5
When the data of the upper magnetic sensors 20f, 20g, and 20h, which are likely to cause thinning of the heat insulating pipe 1, are data D6, D7, and D8, respectively, the difference between all the data D1 to D8 is an average value A, Data D′ 1 to D′ 8. That is, in this process, the average value A is used as a threshold value for determining whether there is an abnormal value. If the value of the data D′ 1 to D′ 3 is larger than the data D′ 4 to D′ 8, it is determined as an abnormal value, and a thinned portion exists in the inspected site detected by the upper magnetic sensors 20f, 20g, and 20h. Judge that.

[Fourth Embodiment]
Hereinafter, the pipe inspection apparatus according to the fourth embodiment will be described. The piping inspection device of the fourth embodiment is a partial modification of the piping inspection device of the first embodiment, and matters that are not particularly described are the same as those of the piping inspection device of the first embodiment.

  As shown in FIG. 12, the magnetic sensor 20 is on the inspection base 30 and is two-dimensionally arranged between the pair of coils 10a and 10b. Specifically, in the example of FIG. 12, the magnetic sensor 20 is provided in three rows and eight rows along the long side of the inspection base 30 on the center side in the circumferential direction of the inspection base 30. Are covered with the test base 30 at substantially equal intervals around the entire circumference of the heat insulating pipe 1. Thus, by arranging the magnetic sensor 20 two-dimensionally, it is possible to perform more accurate mapping in which the presence or absence of the thinned portion is associated with the spatial position.

  The pipe inspection apparatus according to the embodiment has been described above. However, the pipe inspection apparatus according to the present invention is not limited to the above example. For example, in the above embodiment, the pipe inspection apparatus 100 of FIG. 1 uses the remote pulse method, but can also be used for various detection methods such as eddy current flaw detection. In this case, magnetic data is obtained according to each detection method. In addition, the pipe inspection apparatus 100 of the above embodiment can be used for an apparatus in which the configuration of the excitation coil 10 is different and the magnetic flux density distribution due to the excitation coil 10 appears remarkably.

  Moreover, in the said embodiment, the threshold value which determines the presence or absence of a piping defect signal can be set suitably.

  Moreover, in the said embodiment, arrangement | positioning of the exciting coil 10 is a mere illustration, and you may provide a core in the exciting coil 10. FIG.

  In the above embodiment, a plurality of magnetic sensors 20 may be provided along a radial direction that passes through the central axis AX of the heat insulating pipe 1 and is perpendicular to the central axis AX. The magnetic field detected at the radial position of the heat insulating pipe 1 is proportional to the strength of the magnetic flux source due to the thinning, that is, the defect, but the magnetic field strength that 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, and it can be determined whether or not the defect is on the pipe 1a. As a specific method, the magnetic field strength at two or more observation points is approximated by a curve having a reciprocal of the square of the distance from the pipe 1a and a curve having a reciprocal of the square of the distance from the exterior plate 1c. By performing the fitting, it is possible to clearly determine whether the defect exists in the pipe 1a or the exterior plate 1c.

  DESCRIPTION OF SYMBOLS 1 ... Heat insulation piping, 1a ... Piping, 1b ... Heat insulation material, 1c ... Exterior board, 10 ... Excitation coil, 10a, 10b ... Coil, 20, 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h ... Magnetic sensor 30 ... Inspection base, 40 ... Pulse power supply, 50 ... Magnetic sensor circuit, 60 ... Movement mechanism, 70 ... Control unit, 80 ... Inspection unit, 100 ... Pipe inspection device, AX ... Center axis, OS ... Top

Claims (10)

An exciting coil that provides magnetism to the insulated pipe;
A plurality of magnetic sensors arranged around the exciting coil;
With
At the position of each magnetic sensor, the amount of magnetism generated by the excitation coil and the direction of the magnetism are acquired as reference data on the premise of standard heat insulation piping,
A pipe inspection apparatus that obtains a pipe defect signal representing a thinning of a heat insulating pipe from the reference data and magnetic data obtained by detecting the heat insulating pipe to be inspected by the magnetic sensor.   The piping according to claim 1, wherein the reference data is calculated by a simulation in consideration of an installation state of a heat insulating pipe to be inspected, an exterior plate of the heat insulating pipe, the excitation coil, and the magnetic sensor. Inspection device.   The pipe inspection apparatus according to claim 1, wherein the reference data corresponds to a heat insulating pipe to be inspected, but is obtained by measuring in advance a value of a normal pipe that is not thinned.   The pipe inspection apparatus according to claim 1, wherein the reference data is obtained by measuring, in real time, a part of magnetic data of a heat insulating pipe to be inspected.   The reference data is obtained by measuring at least a part of magnetic data in a region of 60 ° to 240 ° below the heat insulating pipe with reference to the uppermost apex of the heat insulating pipe to be inspected. The piping inspection device according to claim 4.   The pipe inspection apparatus according to claim 1, wherein a pipe defect signal is obtained by adding the reciprocal of the reference data to the magnetic data.   The pipe inspection apparatus according to any one of claims 1 to 5, wherein a pipe defect signal is obtained by subtracting the reference data from the magnetic data.   The pipe inspection apparatus according to claim 1, wherein the excitation coil is disposed along a circumference of the heat insulating pipe.   The pipe inspection device according to any one of claims 1 to 8, wherein the magnetic sensor is provided at a plurality of locations along a circumference of a cross-sectional pipe.   The pipe inspection apparatus according to claim 1, wherein the magnetic sensor is provided at a plurality of locations along a central axis direction of the cross-sectional pipe.

Images