JP4005159B2 - How to identify damaged sections of a pipeline - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for identifying a section where damage has occurred when detecting damage to a pipeline laid over a long distance.
[0002]
[Prior art]
Conventionally, pipelines for transporting city gas have been buried in the ground for a long distance and coated with an electrically insulating synthetic resin called coating for preventing corrosion. Soil excavation work is performed in the vicinity where the pipeline is buried, and the coating is damaged by the collision of heavy equipment for excavation, such as excavator backhoes and excavator drill augers, and the main metal pipe in the pipeline If the surface of the surface is exposed to the ground, corrosion rapidly proceeds, so it is necessary to quickly detect damage to the coating and perform emergency repair procedures.
[0003]
In order to accurately detect the damage occurrence position, a number of damage detection devices are installed along the pipeline, and it is confirmed that damage has occurred between two specific measurement points. Can be specified. For this purpose, it is necessary to collect information from each measurement point in one place, for example, in the center, and perform a logic judgment process based on the information. Prior art for providing a plurality of measurement points along the underground pipe is also disclosed in, for example, Japanese Patent Application Laid-Open No. 7-128189 by the present applicant.
[0004]
[Problems to be solved by the invention]
In order to identify damaged parts of pipelines that are laid over long distances, if many measurement points are provided and the measurement point nearest to the damage point is specified when damage occurs, the distance between the specified measurement points There is a damage point in this section, and the damage point can be specified more accurately by performing an intensive search for that section. However, until the section is specified, it is necessary to repeat the data communication with each measurement point and advance the section specification while comparing the measurement data at each measurement point. Even if the data from each measurement point is collected in one central station, it is necessary to perform at least one data communication between the central station and each measurement point, and in order to specify one section It is necessary to perform data communication for at least the number of measurement points.
[0005]
Although it is conceivable to use a normal subscriber telephone line for data communication between a central office and a measurement point that are far away from each other, in the worst case, data communication is performed for the number of measurement points, and it is long to specify the section. It may take time. Even if a dedicated communication line is provided, if data communication is performed with all measurement points, it takes a long time, and a line used only for damage detection is a cost required for installation and maintenance. Is big.
[0006]
An object of the present invention is to quickly identify the occurrence section of damage that occurs along the pipeline, and to reduce the number of times of data communication and the like necessary for specifying the section. It is to provide a specific method.
[0007]
[Means for Solving the Problems]
According to the present invention , a plurality of measurement points are arranged along a pipeline, a potential detection unit that detects a potential at each measurement point, a sensor that detects a current at each measurement point, and a potential detected by the potential detection unit. and based on the current detected by the sensor, the damage detection device and a damage determination means for determining whether the damage occurred I by the whether it is possible to detect the potential drop and the current change at the same time, Provided for each measurement point,
Each damage detection device is connected to be communicable with each other. The damage detection device at the central measurement point includes a signal generation device for supplying a detection signal to the pipeline, and when the occurrence of damage is detected, when the potential drops. Depending on whether the current at each measurement point decreases or increases, there is a section specifying means for determining the damage occurrence section by determining the existence direction of the damaged point relative to the measurement point, which is the signal supply side or the opposite side to the pipeline. Provided,
When the occurrence of damage is detected, the section specifying means determines the direction of existence of the damaged part on either side of the section on both sides that bisects the axial direction of the pipeline at the central measurement point,
The discrimination process for discriminating the existence direction at the measurement point that bisects the section of the existence direction detected as the presence of the damaged part is repeated by the section specifying means, and the section between the measurement points where the damage occurrence part exists is determined. A method for identifying a damaged section of a pipeline characterized by identifying.
According to the present invention, at a plurality of measurement points arranged along the pipeline , the potential is detected by the potential detection means of the damage detection device, and the current is detected by the sensor. Further, the damage determination means of each damage detection device determines whether or not damage has occurred based on whether or not the potential drop and the current change are simultaneously measured based on the detected potential and current . When the occurrence of damage is detected in this way, the presence direction of the damaged portion is determined by the section specifying means of the central damage detection device depending on whether the current at each measurement point decreases or increases when the potential decreases . When damage occurs, it is possible to detect on which side of the section on both sides that bisects the pipeline in the axial direction by detecting the direction of presence of the damaged portion at the central measurement point. At the measurement point that further bisects the section where it is detected that the damaged portion exists, the direction in which the damaged portion is present is detected, and the section where the damaged portion is located is specified. Further, the direction in which the damage occurs is detected at the measurement point that bisects the section, and the section where the damage occurs is identified. In this way, the section specifying means of the damage detection device at the central measurement point repeatedly determines which section is damaged while bisecting the section, and damages any section between two adjacent measurement points. We will identify if there is a place . Therefore, even if a large number of measurement points are arranged, if a section identification unit is provided in the central damage detection device, it is possible to identify a damage occurrence section where a damaged portion exists with a small number of processes.
[0008]
Further, the present invention is directed to damage to a coating of a metal pipeline embedded in the ground as the damage.
According to the present invention, since the damaged section is quickly identified for damage to the coating of the metal pipeline buried in the ground, the metal pipeline is protected by damage to the coating. Losing and eroding the damaged area intensively can be avoided by quickly repairing the coating.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic configuration for identifying a damaged section of a pipeline according to an embodiment of the present invention. As shown in (a), 14 measurement points indicated by reference numerals 1 to 14 and a central station 20 having a function of specifying a damaged section from the detection result are arranged along the axial direction of the pipeline 21 of the pipeline. Deploy. The central office 20 is installed near the center of the conduit 21. In the central office 20, a signal generator 22 for supplying an AC detection signal to the conduit 21 is provided. The signal output from the signal generator 22 is supplied between a connection terminal 23 provided on the conduit 21 and a ground electrode 24 for electrical connection to the surrounding soil.
[0010]
(B) shows a schematic cross-sectional configuration of the conduit 21. The periphery of the tube main body 25 made of metal such as steel is covered with a coating 26 made of an electrically insulating synthetic resin material to prevent the surface of the tube main body 25 from being corroded by soil. When such a coating 26 is damaged by a collision with a heavy excavator for soil excavation work, the insulation resistance of the coating 26 is reduced, and the current leaked from the pipe body 25 into the soil is increased.
[0011]
As shown in (a), current sensors 27A and 27B are provided on both sides of the connection terminal 23 of the central office 20, and it is possible to detect the direction in which the signal current increases due to damage to the coating 26. it can.
[0012]
FIG. 2 shows an overall configuration of the coating damage detection system according to the present embodiment. In the central office 20 shown in FIG. 1A, a coil 28 is inserted into a connection path from the signal generator 22 to the connection terminal 23 of the conduit 21. The damage detection device 30 provided in the central office 20 is provided with a potential detection means 31 for detecting the surface potential of the pipe body 25 of the conduit 21 at the connection terminal 23. The potential detected by the potential detecting means 31 is provided with the coil 28 and the output impedance of the equivalent signal generator 22 is increased, so that the sensitivity of potential detection is improved. Current detection means 32 and 33 are connected to the current sensors 27A and 27B, and amplify the current detected by the current sensors 27A and 27B realized by, for example, a current transformer. The outputs of the potential detection means 31 and the current detection means 32 and 33 are given to the damage determination means 34, and it is determined whether or not the coating 26 is damaged by combining the potential change and the current change. Can do. The damage detection device 30 provided in the central office 20 includes a section specifying means 35 for specifying a section where damage has occurred at the time of damage, and a communication process for performing communication for aggregating data for section specification. Means 36 are also included.
[0013]
In each of the measurement points 1 to 14 shown in FIG. 1A, damage detection devices 40 and 50 are installed, and the potential detection means 31, the current detection means 32, the damage determination means 34, and the communication processing means 36 of the damage detection device 30. Potential detection means 41 and 51, current detection means 42 and 52, damage determination means 44 and 54, and communication processing means 46 and 56, respectively. Detection outputs of current sensors 47 and 57 for detecting a signal current flowing through the conduit 21 are given to the current detection means 42 and 52 in the damage detection devices 40 and 50, respectively.
[0014]
Communication processing means 36 of the central office 20 is communication processing means 46, 56 of damage detection devices 40, 50 provided at the respective measurement points 1-14 via communication lines 61, 62, 63, 64 such as subscriber telephone lines. And data communication is possible.
[0015]
FIGS. 3 and 4 show experimental results in which the conduit 21 is simulated to be damaged at the times indicated by (1), (2), (3), (4), (5), and (6). . FIG. 3 shows changes in potential and current on the downstream side in relation to the signal generator 22 relative to the location of damage, and FIG. 4 shows changes in potential and current on the upstream side. Although it is the same that the potential decreases due to the occurrence of damage on the downstream side and the upstream side of the damaged portion, the direction of the change in the current that occurs at the same time is different. On the downstream side, a large amount of signal current leaks from the damage occurrence site into the soil, so that the signal current decreases. On the upstream side, the ground impedance at the location where the damage occurs is reduced, and a large amount of signal current flows, so the amount of current detected also increases.
[0016]
FIG. 5 shows an operation for specifying a section according to the present embodiment. The operation is started from step a1, and in step a2, it is determined whether or not a potential change has occurred. When it is determined that a potential change has occurred, it is determined in step a3 whether or not a current change has been detected. When a potential change and a current change are detected, it is determined in step a4 whether or not the direction of damage occurrence can be determined. For example, in the case of the central office 20, by comparing the detection values of the current sensors 27A and 27B, it can be determined that the coating is damaged in the direction where the increase amount of the current detection value is larger. Further, at other measurement points 1 to 14, as shown in FIGS. 3 and 4, whether the measurement point is on the downstream side or the upstream side of the central station 20 with respect to the damaged portion, the potential change and the current change. And can be discriminated. Such a direction determination cannot be performed if the change is caused by noise.
[0017]
If the direction can be determined in step a4, an intermediate measurement point that bisects the remaining section on the direction side determined in step a5 is selected. In step a6, it is determined whether or not an intermediate measurement point can be selected. When an intermediate measurement point can be selected, the process returns to step a4, and it is further determined whether or not direction determination is possible for the sections on both sides thereof, and the same processing is repeated. If it is determined in step a6 that an intermediate measurement point cannot be selected, it is determined in step a7 whether or not the final section has been reached. When the last section has been reached, it is determined in step a8 that there is a damage point in the section, an alarm is generated in step a9, one section specifying operation is terminated, and the next damage detection operation is started in step a2. . When change detection is not performed in step a2 and step a3, or when direction determination is not possible in step a4, or when it is determined in step a7 that it is not the last section, the process returns to step a2 as a false detection due to noise or the like.
[0018]
As shown in FIG. 1 (a), when 14 measurement points 1 to 14 are provided, the central station 20 constantly monitors the potential, and when a decrease in potential is detected, the current sensors 27A and 27B Confirm the current increase of. When both increase similarly, the direction cannot be determined. If only one of them increases, the communication process for specifying the damaged section can be started.
[0019]
Assuming that the current sensor 27A detects an increase in current, measurement points 1 to 7 are provided on the current increase side of the current sensor 27A. The intermediate measurement point 4 is selected, and the potential detection data and the current detection data are read through the communication lines 61 to 64 shown in FIG. 2, and the potential decrease and the current change direction are confirmed. If the current increases, it is determined that damage has occurred further downstream, and a communication line is connected to the measurement point 6. At the measurement point 6, the decrease in potential and the direction of current change are confirmed. If the current increases, the communication line is connected to the measurement point 7, and if it decreases, the communication line is connected to the measurement point 5. When a communication line is connected to the measurement point 5, the potential decrease and the current change direction are confirmed at the measurement point 5. If the current is increasing, the section between the measurement point 5 and the measurement point 6, the current Can be determined that damage has occurred in the section between the measurement point 4 and the measurement point 5. As described above, it is possible to always specify the section with respect to the measurement points 1 to 14 by three communications.
[0020]
In general, when the number of measurement points on one side of the central office 20 does not exceed 2 ⁿ , it is possible to specify a section with a maximum of n communications. Further, the present invention is not limited to a pipeline buried in the ground for transporting city gas. For example, in a pipeline transporting fluid, a partial pressure generated in the pipeline is detected while detecting the pressure and flow rate of the fluid. In the case where fluid leakage occurs due to serious damage, the present invention can be similarly applied to a method for identifying a section where leakage occurs.
[0021]
【The invention's effect】
As described above, according to the present invention, a large number of measurement points can be arranged along the pipeline to quickly identify the measurement point section where the damaged portion exists. It is possible to reduce damage to the pipeline as much as possible.
[0022]
Further, according to the present invention, it is possible to quickly repair the damage to the coating that protects the metal pipeline by specifying the section between the measurement points where the damage occurrence place exists with high accuracy. Can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a basic configuration of an embodiment of the present invention and a cross-sectional view showing a structure of a coating to be a damage detection target.
FIG. 2 is a block diagram showing an electrical configuration of a comprehensive coating damage detection system to which the damage detection method of FIG. 1 is applied.
FIG. 3 is a time chart showing detection results for simulated damage in the embodiment of FIG. 1;
4 is a time chart showing detection results for simulated damage in the embodiment of FIG. 1. FIG.
FIG. 5 is a flowchart showing an operation for specifying a damaged section in the central office 20 of FIG. 1;
[Explanation of symbols]
1 to 14 Measuring point 20 Central station 21 Conduit 22 Signal generator 25 Pipe body 26 Coating 27A, 27B, 47, 57 Current sensor 28 Coil 30, 40, 50 Damage detection device 31, 41, 51 Potential detection means 32, 33, 42, 52 Current detection means 34, 44, 54 Damage determination means 35 Section identification means 36, 46, 56 Communication processing means 61, 62, 63, 64 Communication line

Claims (2)

Along the pipeline, arranging a plurality of measurement points, and the potential detecting means for detecting the potentials at each measurement point, a sensor for detecting the current in each measurement point, detected by the potential sensor which is detected by the potential detection means based on the current, the damage detection device and a damage determination means for determining whether the damage occurred I by the whether it is possible to detect the potential drop and the current change at the same time, each measurement point Provided in
Each damage detection device is connected to be communicable with each other. The damage detection device at the central measurement point includes a signal generation device for supplying a detection signal to the pipeline, and when the occurrence of damage is detected, when the potential drops. Depending on whether the current at each measurement point decreases or increases, there is a section specifying means for determining the damage occurrence section by determining the existence direction of the damaged point relative to the measurement point, which is the signal supply side or the opposite side to the pipeline. Provided,
When the occurrence of damage is detected, the section specifying means determines the direction of existence of the damaged part on either side of the section on both sides that bisects the axial direction of the pipeline at the central measurement point,
The discrimination process for discriminating the existence direction at the measurement point that bisects the section of the existence direction detected as the presence of the damaged part is repeated by the section specifying means, and the section between the measurement points where the damage occurrence part exists A method for identifying a damaged section of a pipeline, characterized by:   2. The method for identifying a damaged section of a pipeline according to claim 1, wherein the damage is a damage to a coating of a metal pipeline buried in the ground.

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