Inspection device, method for inspection, and inspection program

Abstract

To inspect the insulation property of a pipe including an insulation joint.SOLUTION: The present invention has a first part P1 and a second part P2. When the insulation property between the first part P1 and the second part P2 of a conductive pipe SP including a part connected between the first part P1 and the second part P2 by an insulative joint IF is inspected, the capacitance CA between a first terminal 110 for contact with the first part P1 and a second terminal 120 for contact with the second part P2 is measured and the insulation property between the first part P1 and the second part P2 of the pipe SP is inspected on the basis of the value of the capacitance CA measured in the measurement step.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an inspection device, an inspection method, and an inspection program. [Background technology]

[0002] When connecting two steel pipes made of dissimilar metals, insulating joints are used to prevent galvanic corrosion (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-225050 A Summary of the Invention [Problem to be solved by the invention]

[0004] If an extremely high voltage is applied to an insulating joint due to a lightning strike or other cause, insulation breakdown may occur and the insulating properties of the insulating joint may deteriorate.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to inspect the insulation of a pipe including an insulating joint. [Means for solving the problem]

[0006] In order to solve the above problem, an inspection device according to one embodiment of the present invention is an inspection device that inspects the insulation between a first part and a second part of a conductive tube including a portion connected between the first part and the second part by an insulating joint, and has a first terminal for contacting the first part, a second terminal for contacting the second part, and an inspection unit that measures the capacitance between the first terminal and the second terminal and inspects the insulation between the first part and the second part based on the measured capacitance value.

[0007] Moreover, an inspection method according to an embodiment of the present invention is an inspection method for inspecting insulation between a first portion and a second portion of a conductive tube including a portion connected between the first portion and the second portion by an insulating joint, the inspection method including a measurement step of measuring a capacitance between a first terminal for contacting the first portion and a second terminal for contacting the second portion, and an inspection step of inspecting insulation between the first portion and the second portion based on a value of the capacitance measured in the measurement step.

[0008] Moreover, a program according to an embodiment of the present invention causes a computer to execute the above inspection method. Effect of the Invention

[0009] The present invention makes it possible to inspect the insulation of a pipe containing insulating joints. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing an inspection apparatus 100 according to an embodiment of the present invention. [Diagram 2] 1 is a diagram showing an inspection apparatus 100 according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating a state in which the first terminal 110 (second terminal 120) is in contact with the first portion P1 (second portion P2) of the tube SP. [Figure 4] 1 is a diagram illustrating a gap G that occurs between a first terminal 110 (a second terminal 120) and a pipe SP. FIG. [Diagram 5] 2 is a diagram illustrating the capacitance between a first terminal 110 and a second terminal 120. FIG. [Figure 6] 2 is a diagram illustrating the capacitance between a first terminal 110 and a second terminal 120. FIG. [Figure 7] 3 is a diagram showing an example of a processing operation executed in the inspection device 100. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Inspection device 100> 1 and 2 are diagrams showing an inspection device 100 according to an embodiment of the present invention. The inspection device 100 inspects the insulation of a pipe SP having a first portion P1 and a second portion P2, including a portion connected between the first portion P1 and the second portion P2 by an insulating joint IF. The pipe SP is a conductive pipe, such as a steel pipe (e.g., a gas pipe or a water pipe).

[0012] In the example shown in Fig. 1, the pipe SP has a first portion P1, a second portion P2, and one insulating joint IF, and this one insulating joint IF connects the first portion P1 and the second portion P2. As shown in Fig. 2, the pipe SP may have another portion OP other than the first portion P1 and the second portion P2 between the first portion P1 and the second portion P2, and may have two or more insulating joints IF, and each of these two or more insulating joints IF may connect the first portion P1 to the other portion OP, the second portion P2 to the other portion OP, or the other portions OP to each other.

[0013] The inspection device 100 includes a first terminal 110, a second terminal 120, and an inspection section .

[0014] 1 and 2, the first terminal 110 is a terminal for contacting the first portion P1 of the tube SP, and the second terminal 120 is a terminal for contacting the first portion P1 of the tube SP. The first terminal 110 (second terminal 120) is kept in contact with the first portion P1 (second portion P2) of the tube SP by, for example, a device (the terminal fixing device shown in FIG. 3).

[0015] The inspection unit 130 measures the capacitance CA between the first terminal 110 and the second terminal 120 (i.e., the capacitance between the first part P1 of the tube SP with which the first terminal 110 contacts and the second part P2 of the tube SP with which the second terminal 120 contacts), and inspects the insulation between the first part P1 and the second part P2 of the tube SP based on the value of the measured capacitance CA. The inspection unit 130 performs the above process (measuring the capacitance CA and inspecting the insulation of the tube SP) at predetermined time intervals, for example.

[0016] For example, the inspection unit 130 applies an AC voltage to the tube SP from the first terminal 110 and the second terminal 120, and measures a current generated by this AC voltage. For example, the inspection unit 130 measures the capacitance CA between the first terminal 110 and the second terminal 120 by calculating the capacitance or impedance between the first terminal 110 and the second terminal 120 using the measured current.

[0017] The larger the value of the capacitance CA between the first terminal 110 and the second terminal 120, the greater the insulation between the first portion P1 and the second portion P2 of the pipe SP. Therefore, if the measured value of the capacitance CA is smaller than the first capacitance value C1, the inspection unit 130 determines that the insulation between the first portion P1 and the second portion P2 of the pipe SP (i.e., the insulation of the insulating joint IF) has decreased. Here, the first capacitance value C1 is set appropriately.

[0018] As described above, in this embodiment, it is possible to inspect the insulation of a pipe including an insulating joint. In particular, in this embodiment, as described in detail below, it is possible to inspect the insulation of a pipe including an insulating joint after determining whether or not poor contact occurs between the first terminal 110 (second terminal 120) and the first part P1 (second part P2) of the pipe SP (that is, whether or not a gap G or an oxide film is formed, as described in detail below).

[0019] In addition, if there is no poor contact between the first terminal 110 (second terminal 120) and the first part P1 (second part P2) of the tube SP, the insulation between the first part P1 and the second part P2 of the tube SP can also be inspected by applying a DC voltage to the tube SP via the first terminal 110 and the second terminal 120 and measuring the resistance value between the first terminal 110 and the second terminal 120. If there is no poor contact between the first terminal 110 (second terminal 120) and the first part P1 (second part P2) of the tube SP, and if the insulation between the first part P1 and the second part P2 of the tube SP is normal, there is no continuity between the first terminal 110 and the second terminal 120 (i.e., between the first part P1 and the second part P2 of the tube SP), but if the insulation between the first part P1 and the second part P2 of the tube SP deteriorates, conductivity begins to develop between the first terminal 110 and the second terminal 120, and the resistance value between the first terminal 110 and the second terminal 120 decreases.

[0020] However, when poor contact occurs between the first terminal 110 (second terminal 120) and the first part P1 (second part P2) of the tube SP, the above-mentioned method of applying a DC voltage cannot inspect the insulation between the first part P1 and the second part P2 of the tube SP. When poor contact occurs between the first terminal 110 (second terminal 120) and the first part P1 (second part P2) of the tube SP, the first terminal 110 and the second terminal 120 are kept in a non-conductive state due to the poor contact, and even if the insulation between the first part P1 and the second part P2 of the tube SP is reduced, the resistance value between the first terminal 110 and the second terminal 120 does not decrease, and the reduction in the insulation between the first part P1 and the second part P2 of the tube SP cannot be detected.

[0021] <Reduction in capacitance due to voids> The first terminal 110 (second terminal 120) is kept in contact with the first portion P1 (second portion P2) of the tube SP, for example, by using a terminal fixing tool as shown in Fig. 3. When the tube SP is covered with a protective layer such as a protective cover as shown in Fig. 3, for example, a part of the protective layer covering the first portion P1 (second portion SP2) of the tube SP is removed, and the first terminal 110 (second terminal 120) is brought into contact with the first portion P1 (second portion SP2) of the tube SP at the portion where the protective layer has been removed.

[0022] In the terminal fastener shown in Fig. 3, the first terminal 110 (second terminal 120) is pressed against the first portion P1 (second portion P2) of the tube SP by the restoring force of the spring S. Therefore, in the terminal fastener shown in Fig. 3, if the spring S is damaged and the first terminal 110 (second terminal 120) cannot be pressed against the first portion P1 (second portion P2) of the tube SP by the restoring force of the spring S, as shown in Fig. 4, the first terminal 110 (second terminal 120) does not contact the first portion P1 (second portion P2) of the tube SP, and a gap G may be generated between the first terminal 110 (second terminal 120) and the first portion P1 (second portion P2) of the tube SP.

[0023] When a gap G occurs between the first terminal 110 (second terminal 120) and the first portion P1 (second portion P2) of the pipe SP, the capacitance CA between the first terminal 110 and the second terminal 120 is a series connection of the capacitance CF of the insulating joint IF and the capacitance CG due to the gap G, as shown in Fig. 5. If the area of ​​the portion of the surface of the first terminal 110 (second terminal 120) that contacts the first portion P1 (second portion P2) is π mm 2 If the gap G is several mm in size, the value of the capacitance CG due to the gap G is several pF, which is significantly smaller (CG<<CF) than the value of the capacitance CF of the insulating joint IF under normal conditions (several hundred pF (e.g., 300 pF)).

[0024] Therefore, when a gap G occurs between the first terminal 110 (second terminal 120) and the first part P1 (second part P2) of the tube SP, if the capacitance CF of the insulating joint IF is normal, the value of the capacitance CA between the first terminal 110 and the second terminal 120 will be approximately the same as the value of the capacitance CG due to the gap G (CA ≈ CG). For this reason, when a gap G occurs between the first terminal 110 (second terminal 120) and the first part P1 (second part P2) of the tube SP, even if the capacitance CF of the insulating joint IF is normal, the value of the capacitance CA between the first terminal 110 and the second terminal 120 will be much smaller compared to the value of the capacitance CF of the insulating joint IF when it is normal (CA ≪ CF).

[0025] Therefore, if the measured value of the capacitance CA is equal to or greater than the second capacitance value C2 and less than the third capacitance value C3, it is advisable for the inspection unit 130 to determine that there is a gap G between the first terminal 110 and the first part P1 of the tube SP and / or between the second terminal 120 and the second part P2 of the tube SP. Here, the third capacitance value C3 is smaller than the first capacitance value C1 and greater than the second capacitance value C2 (C2 < C3 < C1). The second capacitance value C2 and the third capacitance value C3 are appropriately set based on parameters that determine the value of the capacitance CG due to the gap G, such as the size of the possible gap G and the area of the surface of the first terminal 110 (second terminal 120) that contacts the first part P1 (second part P2).

[0026] And if the measured value of the capacitance CA is equal to or greater than the third capacitance C3 and less than the first capacitance value C1, it is advisable for the inspection unit 130 to determine that the insulation between the first part P1 and the second part P2 of the tube SP has deteriorated.

[0027] By doing this, when a decrease in the capacitance CA measured by the inspection unit 130 occurs, it is possible to determine whether this decrease in capacitance is due to a decrease in the capacitance CF of the insulating joint IF (i.e., a decrease in the insulation between the first part P1 and the second part P2 of the pipe SP) or due to the occurrence of a gap G, and then inspect the insulation between the first part P1 and the second part P2 of the pipe SP.

[0028] <Reduction in capacitance due to formation of oxide film> An oxide film is formed on the surface of the tube SP when it comes into contact with air. When an oxide film is formed on the portion of the surface of the first part P1 (second part P2) of the tube SP that contacts the first terminal 110 (second terminal 120), the capacitance CA between the first terminal 110 and the second terminal 120 is the capacitance CF of the insulating joint IF and the capacitance CO due to the oxide film connected in series, as shown in FIG. 6. If the area of ​​the portion of the surface of the first terminal 110 (second terminal 120) that contacts the first part P1 (second part P2) is π mm 2 If the thickness of the oxide film is approximately several tens of nm, the capacitance CO due to the oxide film will be several pF, which is significantly smaller than the capacitance CF of the insulating joint IF under normal conditions (several hundred pF (e.g., 300 pF)) (CO<CF).

[0029] Therefore, when an oxide film is formed on the surface of the first part P1 (second part P2) of the tube SP where the first terminal 110 (second terminal 120) contacts, if the capacitance CF of the insulating joint IF is normal, the value of the capacitance CA between the first terminal 110 and the second terminal 120 will be approximately the same as the value of the capacitance CO due to the oxide film (CA ≒ CO). Therefore, when an oxide film is formed on the surface of the first part P1 (second part P2) of the tube SP where the first terminal 110 (second terminal 120) contacts, even if the capacitance CF of the insulating joint IF is normal, the value of the capacitance CA between the first terminal 110 and the second terminal 120 will be significantly smaller than the value of the capacitance CF of the insulating joint IF when it is normal (CA << CF).

[0030] Therefore, if the measured capacitance value CA is equal to or greater than the fourth capacitance value C4 and less than the fifth capacitance value C5, the inspection unit 130 may be configured to determine that an oxide film is formed on the portion of the surface of the first part P1 that contacts the first terminal 110 and / or on the portion of the surface of the first part P2 that contacts the second terminal 120. The fifth capacitance value C5 is less than the first capacitance value C1 and greater than the fourth capacitance value C4 (C4 < C5 < C1). The fourth capacitance value C4 and the fifth capacitance value C5 are appropriately set based on parameters that determine the value of the capacitance CO due to the oxide film, such as the thickness of the oxide film that can be formed on the portion of the surface of the first part P1 (second part P2) that contacts the first terminal 110 (second terminal 120) and the area of the portion of the surface of the first terminal 110 (second terminal 120) that contacts the first part P1 (second part P2).

[0031] And, if the measured capacitance value CA is equal to or greater than the fifth capacitance C5 and less than the first capacitance value C1, the inspection unit 130 may be configured to determine that the insulation between the first part P1 and the second part P2 of the pipe SP has deteriorated.

[0032] By doing so, when a decrease in the capacitance CA measured by the inspection unit 130 occurs, it is possible to determine whether this decrease in capacitance is due to a decrease in the capacitance CF of the insulating joint IF (i.e., a decrease in the insulation between the first part P1 and the second part P2 of the pipe SP) or due to the formation of an oxide film, and then inspect the insulation between the first part P1 and the second part P2 of the pipe SP.

[0033] <Discrimination between void generation and oxide film formation> Assuming that the relative permittivity of air is ε1 and the relative permittivity of the oxide film is ε2, then ε1 < ε2. Therefore, if the gap G is about several millimeters and the thickness of the oxide film is about several tens of nanometers, the value of the capacitance CG due to the gap G is smaller than the value of the capacitance CO due to the oxide film (CG < CO). Thus, it is preferable that the third capacitance value C3 is smaller than the fourth capacitance value C4 (C3 < C4).

[0034] Then, if the value of the measured capacitance CA is greater than or equal to the second capacitance value C2 and smaller than the third capacitance value C3, the inspection unit 130 determines that there is a gap G between the first terminal 110 and the first portion P1, and / or between the second terminal 120 and the second portion P2. If the value of the measured capacitance CA is greater than or equal to the fourth capacitance value C4 and smaller than the fifth capacitance value C5, it is preferable that the inspection unit 130 determines that an oxide film is formed on the portion of the surface of the first portion P1 that contacts the first terminal 110 and / or on the portion of the surface of the second portion P2 that contacts the second terminal 120. At this time, if the value of the measured capacitance CA is greater than or equal to the fifth capacitance C5 and smaller than the first capacitance value C1, it is preferable that the inspection unit 130 determines that the insulation between the first portion P1 and the second portion P2 of the tube SP has deteriorated.

[0035] By doing so, when a decrease in the capacitance CA measured by the inspection unit 130 occurs, it is possible to determine whether this capacitance decrease is due to a decrease in the capacitance CF of the insulating joint IF (i.e., a decrease in the insulation between the first portion P1 and the second portion P2 of the tube SP), due to the generation of the gap G, or due to the formation of the oxide film, and then inspect the insulation between the first portion P1 and the second portion P2 of the tube SP.

[0036] There is a possibility that an abnormality other than the occurrence of voids G or the formation of an oxide film occurs in the inspection device 100, and the measured value of the capacitance CA takes a value outside the above range. Therefore, for example, if the measured value of the capacitance CA is equal to or greater than the third capacitance value C3 and smaller than the fourth capacitance value C4, the inspection unit 130 may determine that an abnormality other than the occurrence of voids G or the formation of an oxide film occurs in the inspection device 100. Similarly, if the measured value of the capacitance CA is smaller than the second capacitance value C2, the inspection unit 130 may determine that an abnormality other than the occurrence of voids G or the formation of an oxide film occurs in the inspection device 100.

[0037] <Notification section 140> The inspection device 100 may further include a notification unit 140 that notifies the result of the inspection by the inspection unit 130. The notification unit 140 is, for example, a display device such as a display that displays information, a printing device such as a printer that outputs a printed copy of information, or an audio output device such as a speaker that outputs audio related to the information.

[0038] For example, if the inspection unit 130 determines that the insulation between the first portion P1 and the second portion P2 of the pipe SP has deteriorated, the notification unit 140 notifies that the insulation between the first portion P1 and the second portion P2 of the pipe SP has deteriorated. Also, if the inspection unit 130 determines that a gap G exists between the first terminal 110 and the first portion P1 and / or between the second terminal 120 and the second portion P2, the notification unit 140 notifies that a gap G exists. Also, if the inspection unit 130 determines that an oxide film has been formed on a portion of the surface of the first portion P1 that contacts the first terminal 110 and / or a portion of the second portion P2 that contacts the second terminal 120, the notification unit 140 notifies that an oxide film has been formed.

[0039] Furthermore, if the inspection unit 130 determines that an abnormality other than the occurrence of a void G or the formation of an oxide film has occurred in the inspection device 100, the notification unit 140 notifies the inspection device 100 that an abnormality has occurred.

[0040] <Processing operations performed in the inspection device 100> Fig. 7 is a diagram showing an example of a processing operation executed in the inspection device 100. The processing operation shown in Fig. 7 is executed, for example, at predetermined time intervals.

[0041] The inspection unit 130 measures the capacitance CA between the first terminal 110 and the second terminal 120 (step S701). If the value of the measured capacitance CA is equal to or greater than the first capacitance value C1 (step S702, YES), the process ends.

[0042] If the measured capacitance CA is smaller than the first capacitance value C1 (step S702, NO) and greater than or equal to the fifth capacitance value C5 (step S703, YES), the inspection unit 130 determines that the insulation between the first part P1 and the second part P2 of the pipe SP has deteriorated (step S704), and the notification unit 140 notifies that the insulation between the first part P1 and the second part P2 of the pipe SP has deteriorated (step S705).

[0043] If the measured capacitance CA is smaller than the fifth capacitance value C5 (step S703, NO) and greater than or equal to the fourth capacitance value C4 (step S706, YES), the inspection unit 130 determines that an oxide film is formed on the portion of the surface of the first portion P1 that contacts the first terminal 110 and / or the portion of the surface of the second portion P2 that contacts the second terminal 120 (step S707), and the notification unit 140 notifies that an oxide film is formed (step S708).

[0044] If the measured capacitance CA is smaller than the fourth capacitance value C4 (step S706, NO) and is greater than or equal to the third capacitance value C3 (step S709, YES), the inspection unit 130 determines that an abnormality other than the occurrence of a void G or the formation of an oxide film has occurred in the inspection device 100 (step S710), and the notification unit 140 notifies the inspection device 100 that an abnormality has occurred (step S711).

[0045] If the measured capacitance CA is smaller than the third capacitance value C3 (step S709, NO) and greater than or equal to the second capacitance value C2 (step 712, YES), the inspection unit 130 determines that a gap G exists between the first terminal 110 and the first portion P1 and / or between the second terminal 120 and the second portion P2 (step S713), and the notification unit 140 notifies that a gap G exists (step S714).

[0046] If the measured capacitance CA is smaller than the second capacitance value C2 (step S712, NO), the inspection unit 130 determines that an abnormality other than the occurrence of a void G or the formation of an oxide film has occurred in the inspection device 100 (step S710), and the notification unit 140 notifies the inspection device 100 that an abnormality has occurred (step S711).

[0047] The present invention has been described above in terms of preferred embodiments thereof. Although the present invention has been described herein with reference to specific examples, various modifications and variations can be made to these examples without departing from the spirit and scope of the present invention as set forth in the claims. [Explanation of symbols]

[0048] 100 Inspection Equipment 110 First terminal 120 Second Terminal 130 Inspection Department 140 Notification Department

Claims

1. An inspection device for inspecting insulation between a first portion and a second portion of a conductive pipe including a portion connected between the first portion and the second portion by an insulating joint, comprising: a first terminal for contacting the first portion; a second terminal for contacting the second portion; and an inspection unit that measures a capacitance between the first terminal and the second terminal, and inspects insulation between the first portion and the second portion based on the measured capacitance value.

2. 2. The inspection device according to claim 1, wherein the inspection unit determines that insulation between the first portion and the second portion has deteriorated if the measured capacitance value is smaller than a first capacitance value.

3. The inspection unit includes: determining that an air gap exists between the first terminal and the first portion and / or between the second terminal and the second portion if the measured capacitance value is greater than or equal to a second capacitance value and less than a third capacitance value greater than the second capacitance value; 2. The inspection device according to claim 1, wherein if the measured capacitance value is greater than or equal to the third capacitance and less than a first capacitance value greater than the third capacitance, it is determined that insulation between the first portion and the second portion has deteriorated.

4. The inspection unit includes: if the measured capacitance value is equal to or greater than a fourth capacitance value and smaller than a fifth capacitance value that is greater than the fourth capacitance value, it is determined that an oxide film is formed on a portion of the surface of the first portion that contacts the first terminal and / or a portion of the surface of the second portion that contacts the second terminal; 2. The inspection device according to claim 1, wherein if the measured capacitance value is greater than or equal to the fifth capacitance and less than a first capacitance value greater than the fifth capacitance, it is determined that insulation between the first portion and the second portion has deteriorated.

5. The inspection unit includes: determining that an air gap exists between the first terminal and the first portion and / or between the second terminal and the second portion if the measured capacitance value is greater than or equal to a second capacitance value and less than a third capacitance value greater than the second capacitance value; if the measured capacitance value is equal to or greater than a fourth capacitance value that is greater than the third capacitance value and is smaller than a fifth capacitance value that is greater than the fourth capacitance value, it is determined that an oxide film is formed on a portion of the surface of the first portion that contacts the first terminal and / or a portion of the surface of the second portion that contacts the second terminal; 2. The inspection device according to claim 1, wherein if the measured capacitance value is greater than or equal to the fifth capacitance and less than a first capacitance value greater than the fifth capacitance, it is determined that insulation between the first portion and the second portion has deteriorated.

6. 6. The inspection device according to claim 1, wherein the pipe is a gas pipe or a water pipe.

7. The inspection unit includes: Applying an AC voltage to the tube from the first terminal and the second terminal, and measuring a value of a current flowing due to the AC voltage; 6. The inspection device according to claim 1, wherein the capacitance between the first terminal and the second terminal is measured by calculating the capacitance or impedance between the first terminal and the second terminal using the measured current value.

8. The inspection device according to claim 1 , further comprising a notification unit that notifies a result of the inspection by the inspection unit.

9. 1. A computer-implemented inspection method for inspecting insulation between a first portion and a second portion of an electrically conductive tube including a portion connected between the first portion and the second portion by an insulating joint, the method comprising: a measuring step of measuring a capacitance between a first terminal for contacting the first portion and a second terminal for contacting the second portion; and an inspection step of inspecting insulation between the first portion and the second portion based on the capacitance value measured in the measurement step.

10. An inspection program that causes a computer to execute the inspection method according to claim 9.

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