JP2007033133A - Method and system for monitoring corrosion prevention state - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a system for monitoring a corrosion prevention state, where a function is installed for detecting a troublesome state (for example, damage on a coating) for maintaining an excellent corrosion prevention state with position accuracy to the degree between each observation point. <P>SOLUTION: When monitoring the corrosion prevention state of a buried metal to which a coating and electric protection is applied, a direct-current measuring device 1 for measuring in the noncontact state the magnitude and the flowing direction of a protective current for the buried metal at at least one measuring spot is mounted so that a magnetic path is interlinked with the protective current. The current quantity and the flowing direction of the protective current measured by the direct-current measuring device 1 are discriminated, and a protective potential and a direct-current measured value at the measuring spot are discriminated based on the discriminated current quantity and flowing direction of the protective current, and the corrosion prevention state of the coating and the buried metal is evaluated based on the discriminated protective potential and direct-current measured value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an anticorrosion state monitoring method and system for monitoring an anticorrosion state in a buried metal pipe or the like subjected to anticorrosion.

  In order to prevent leakage accidents caused by corrosion of steel pipes, buried pipes typified by domestic high-pressure gas pipes are coated with a coating such as polyethylene on the outer surface that comes into contact with the soil, and the coating is defective. In order to prevent the defective part from being corroded, the anticorrosion is used together. As a method for preventing corrosion of buried objects, a method of creating a cathodic protection state by lowering the potential of the object to be protected in the base direction by using an external power source or a sacrificial anode has been conventionally used. Is required to be maintained.

  Conventionally, as a method of monitoring the anticorrosion state of a buried conduit that has become the mainstream, the potential of the buried conduit with respect to a standard electrode is measured, and if the potential is below a specified value, it is acceptable. By measuring the tube-to-ground potential by connecting a DC potentiometer between the terminal cable connected to the buried conduit and the reference electrode installed on the ground surface in the terminal box installed at an interval of 200 to 1,000 m on the buried conduit This will be done.

  Moreover, in the external power supply system in which a direct current power source is set on the ground and a direct current voltage is applied between the anticorrosion object and the ground electrode, the anticorrosion current output of the power supply unit is read to monitor the anticorrosion state.

  In addition, in the cathodic protection method of the galvanic anode method in which a large number of sacrificial anodes such as magnesium are dispersed and embedded in the vicinity of the conduit and electrically connected to the conduit by a terminal cable, in addition to the pipe-to-ground potential, the terminal cable Insert a shunt resistor and measure the current generated at the anode.

  As another method for monitoring the anticorrosion state, a metal pit (hereinafter referred to as a probe) is assumed to be simulated damage and is driven in the vicinity of the buried point, electrically connected to the anticorrosion object, and the anticorrosive current flowing therethrough is measured. In some cases, the anticorrosion state is confirmed.

  Further, if the coating of the conduit is damaged for some reason and left as it is in the soil, the anticorrosion state deteriorates, and thus a technique for detecting such a damaged part has been proposed.

Patent Document 1 discloses a method of estimating damage by applying many types of AC signals to a conduit and measuring signal current and voltage at each measurement point.
JP-A-8-145934

  Conventional anticorrosion management includes the above-described potential monitoring, monitoring by a probe, and output monitoring of an external power supply device.

In the potential monitoring, even if the tube-to-ground potential measured by the terminal box is kept lower than the reference potential, a large-scale structure comes into contact with the environment around the damaged part, for example, the damaged part of the coating. In some cases, a large amount of anticorrosion current flows into the contact area. In such a case, it is not possible to directly check whether or not a sufficient current flows for the originally intended anticorrosion target, and there is a possibility that the progress of corrosion may be overlooked.

  The same applies to the monitoring by the probe, and since the anticorrosion current depends on the environment, even if a sufficient anticorrosion current is confirmed by the probe, it is said that a sufficient anticorrosion current flows directly into the damaged part. It does not lead to a point.

  In the output monitoring of the anticorrosive current by the external power supply device, the anticorrosive current in the vicinity of the external power connection can be sufficiently identified, but the anticorrosive current distribution in the entire buried conduit as the anticorrosion target cannot be grasped. There was a problem.

  In the galvanic anode method, a measuring instrument such as a shunt must be connected in the circuit when measuring the anode current.

  For this reason, in the anticorrosion management of buried conduits over long distances as described above, the anticorrosion current flowing in the conduits could not be directly measured. Therefore, conventional methods with uncertainties such as potential monitoring, probe monitoring or power output monitoring. There was a need to add a new monitoring method to the anticorrosion state monitoring method.

  Incidentally, various techniques have been developed in the past for detecting defects in coatings that hinder good anticorrosion conditions.

  For example, in a configuration in which many types of AC signals are applied to a conduit represented by Patent Document 1 and damage is estimated by measuring signal current and voltage at each measurement point, the AC signal to the monitoring target section over a long distance is used. By application, the propagation of the signal shows the propagation form seen in the distribution constant, does not show the monotonous attenuation as in the case of applying the direct current, and becomes the propagation form showing the swell represented by the ferrant phenomenon. For this reason, a simple damage determination criterion cannot be applied, and since the propagation form changes in a complicated manner due to damage, an erroneous determination regarding the detection of damage is likely to occur and the detection may be impossible. In addition, the number of components of the system has increased, causing problems such as an increase in apparatus cost and maintenance cost.

Therefore, the present invention has been devised in view of the above-described problems, and the purpose of the present invention is to create a situation that is inconvenient for maintaining a good anticorrosion situation (for example, damage to the coating). An object of the present invention is to provide an anticorrosion state monitoring method and system in which a function of detecting at a position accuracy between observation points is implemented.

  In order to solve the above-described problems, the anticorrosion state monitoring method to which the present invention is applied is an anticorrosion state monitoring method for monitoring the anticorrosion state of a buried metal subjected to coating and electrocorrosion. At least one measurement point In a non-contact DC measurement device for measuring the magnitude and direction of the anticorrosion current of the buried metal, a sensor unit is mounted so that the magnetic path is linked to the anticorrosion current, and the anticorrosion current measured by the DC measurement device The current amount and the flowing direction of the current are identified, and the DC current measurement value is determined based on the identified current amount and the flowing direction of the anticorrosive current, and the anticorrosion potential is further determined by the anticorrosion potential measuring device. Based on the measured DC current, the anticorrosion state of the coating and buried metal is evaluated.

  Further, the anticorrosion state monitoring system to which the present invention is applied is an anticorrosion state monitoring system that monitors the anticorrosion state of a buried metal that has been coated and catalyzed. The anticorrosion current of the buried metal at at least one measurement point. A direct current measuring device that measures the size and direction of flow in a non-contact manner, an anticorrosive potential measuring device that determines the anticorrosion potential, and a current amount and a flowing direction of the anticorrosive current measured by the direct current measuring device via a communication network And a control device that acquires the anticorrosion potential determined by the anticorrosion potential measuring device via a communication network, and the control device performs direct current based on the current amount and the flowing direction of the identified anticorrosion current. A current measurement value is determined, and the anticorrosion state of the coating and the buried metal is evaluated based on the determined DC current measurement value and the acquired anticorrosion potential.

  In the present invention, the portable anticorrosion current measuring device is used, and the conduit administrator can carry the device and go around the management section, and measure the current amount and direction of the anticorrosive current at the place where the wearable portion can be mounted. Kirchhoff's first law can be applied to the current value measured at each point if the coating is sound and the resistance value is very high, but in a long-distance conduit, the area where the coating is in contact with the soil becomes enormous. For this reason, even if the resistance value of the coating is very high, it attenuates and propagates slightly. Conversely, if a change in the anticorrosion current exceeding a small attenuation is observed between a certain measurement point, it can be estimated that there is a problem that the anticorrosion current is consumed somewhere between these points.

  In addition, since the defect part obtained by the present invention is an approximate position between certain measurement points, when specifying an accurate position, in the section in which the existence of the defect is recognized, for example, Japanese Patent Publication No. 7-52166 described above. A detailed position can be determined using the technique disclosed in the publication.

  Furthermore, when the conventional potential distribution monitoring is used in combination, the resistance value of the conduit can be calculated from the anticorrosion current value and the anticorrosion potential value, and quantitative evaluation becomes possible. The corrosion resistance value at each point, the conventional anticorrosion potential record, and the resistance value of the conduit calculated from these values are monitored and converted to data over a long period of time, and the changes are analyzed to determine the progress of coating deterioration. It is possible to take countermeasures for the estimated and rapidly progressing sections.

  Moreover, in this invention, it is good also as a structure which provides the communication function which transmits a measurement result by a telephone line or the internet to a stationary type anti-corrosion current measuring device. By installing stationary anti-corrosion current measuring devices at multiple locations in the anti-corrosion target area, collecting measurement data at each location in one location and monitoring the current and flow direction of the anti-corrosion current between each location in real time It is possible to grasp the anticorrosion situation of the entire conduit at once. In the anticorrosion system where the anticorrosion power supply is carried out at one discharge point in the same insulation section, the coating using the external power supply system is damaged due to a contact accident of the civil engineering heavy machinery, and the anticorrosion current When the gas flows into the damaged part, the anticorrosive current measurement result of the measuring device arranged in the upstream part (external power supply side) increases by the inflow anticorrosive current to the damaged part. From this, it becomes possible to detect in real time that an anomaly has occurred in a range from the point where the anomaly was measured to the next measurement point in the downstream direction (insulation end direction) of the anticorrosion current.

  Also, in the vicinity of the insulation joint that is the end point of the anticorrosion management section, if the insulation joint performance is normal, the direct current and alternating current values at this point are zero amperes. On the contrary, when a direct current or alternating current in the vicinity of insulation is detected, it becomes possible to determine the performance failure of the insulated joint.

  This method can be applied not only to buried conduits but also to confirming the performance of piping insulation joints such as tanks exposed on land.

  In addition, when the conduit is attached to the bridge at a river crossing or the like, the metal fittings of the fixing bracket and the pipe are metal touched at the bridge, or the steel pipe and the steel bar of the structure are touched at the entrance and exit of the large-scale structure. In this case, since the anticorrosion current flows into the structural reinforcing bars and the like, an enormous anticorrosion current is consumed or the anticorrosion potential becomes precious, resulting in an extremely unfavorable environment in terms of anticorrosion management.

  Such a metal touch can also be detected in the form of an increase in anticorrosion current.

  Further, in the invention according to claim 7, since the insulation control section over a long distance is set and the anticorrosion state is not maintained with a single external power supply, the conduit maintaining the anticorrosion state by connecting two or more external power supplies In the case of applying an anticorrosion method by connecting a plurality of sacrificial anodes, the direction of the anticorrosion current flowing in the DC current measuring device used in this technology is used to specify the source of the anticorrosion current at each station. Can be identified as a power source or sacrificial anode on the upstream side of the current. In such a case, the occurrence of metal touch, which is a problem in the present technology, can detect the occurrence of metal touch because a large fluctuation in the anticorrosion current and inversion and decrease in the direction of current flow are observed before and after the metal touch. .

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

  The anticorrosion state monitoring system 10 to which the present invention is applied is applied to a gas conduit 3 having an insulation section of 18 km, for example, as shown in FIG. Five stations A to E are provided in the insulating section of the gas conduit 3, and the patrolman 2 patrols each station A to E and uses the portable DC current measuring device 1. The anticorrosion current is measured. The station A is provided with an external power supply device 4 for electrically protecting the entire gas conduit 3. The patrolman 2 measures the anticorrosion current at each station A to E by attaching the direct current measuring device 1 to the ground exposed portion of the gas conduit 3 at each station A to E.

  The direct current measuring device 1 can be mounted at a place where the conduit is exposed to the ground like the stations A to E, and can also be mounted at a bridge bridge section, a common mine, or the like. In some cases, it is possible to perform excavation and expose the conduit to mount and measure. Furthermore, when installing semipermanently, it is also possible to carry out excavation work, attach a waterproof DC measuring device in the underground, and embed it as it is to expose only the measuring terminal to the ground surface for measurement.

  As a method for measuring the anticorrosive current, for example, a method of measuring and recording the amount and direction of the anticorrosive current by measuring according to the technology disclosed in International Application No. PCT / JP03 / 07729 may be adopted. If such a technique is used as a component and a DC sensor is attached to the conduit to achieve the balance of the magnetic bridge, it is possible to measure the amount of anticorrosive current flowing through the conduit and the direction in which it flows.

  At this time, the patrolman 2 may perform the management method of the anti-corrosion conventionally performed. This conventional management method includes, for example, various other operations such as measurement of the anticorrosion potential, monitoring of the output of the anticorrosion power supply, and measurement of the probe current when a probe is installed, and other miscellaneous operations of the conduit. The patrolman 2 records the measured current amount and direction of the anticorrosion current as data, and brings it back and stores it as a management record.

  The change of the anticorrosion current measured in each station A to E is shown in FIG. As usual, when polyethylene coating is applied to the gas conduit and the anticorrosion system is configured by an external power supply system, Kirchhoff's first law can be applied if the coating is sound and newly installed. However, when the gas conduit 3 is arranged over a long distance, the area where the coating is in contact with the soil becomes enormous, and even if the resistance value of the conduit is very high, it is attenuated and propagates slightly.

For this reason, even in the gas conduit 3 extending over several tens of kilometers, the external power output is on the order of several hundreds (mA) at most, although it varies depending on the pipe diameter and environment. If the insulation performance is normal in the insulating joint 5b which is the end of the anticorrosion management section, the anticorrosion current at this point is measured as 0 (mA). In the case of the present embodiment, the anticorrosion current propagates from the external power supply 4 toward the insulating joint 5b while being attenuated from 80 (mA) to 0 (mA).

In FIG. 2, a solid line indicates a case where the coating at the time of completion is sound. In addition, when the damage points of the simulated coating are formed by the civil engineering heavy machine 6 between the stations B and C as shown in FIG. 1, the measured values of the anticorrosion current at each station position A to E are shown in FIG. It is indicated by a one-dot chain line.

  The anticorrosion current Id (mA) flows into the damaged point where the damage is added, and returns to the external power supply device 4 of the station A. For this reason, the measured value of the anticorrosion current at the station A and the station B located on the external power supply 4 side from the damage point increases by Id (mA).

  Normally, as the inspection record data analysis method collected by the patrolman 2, the fluctuation of the daily anticorrosion current at each of the measurement points A to E is obtained, and if the fluctuation more than that defined in the management standard is indicated, the anticorrosion situation is indicated. A detailed survey will be conducted in the vicinity of the measurement point where the abnormal data is indicated as being abnormal.

  Also, the insulation joint 5b is monitored by monitoring the insulation performance of the insulation joint 5b by installing a direct current measuring device on the insulation joint 5b, which is the end of the corrosion prevention monitoring section. Normally, if the insulating joint 5b is normal, the anticorrosion current is detected as 0 (mA), and if it is not normal, the anticorrosion current is measured and repair is required.

  FIG. 3 shows the anticorrosion current distribution when the insulation joint 5b at the time of completion is healthy by a one-dot chain line. Further, in FIG. 3, the anticorrosion current distribution in the case where the insulation resistance of the insulating joint 5b is poor and the anticorrosion current Ii flows from the duct in the extending direction is indicated by a solid line. If the performance of the insulating joint 5b is good, the anticorrosion current in the insulating joint 5b is 0 (mA). On the other hand, if the insulating joint 5b is defective, the shift due to the inflow of Ii (mA) is measured at all stations A to E.

  Moreover, in the anticorrosion state monitoring system 1 to which the present invention is applied, it is possible to find a portion where the anticorrosion current is gradually increased or a portion where the anticorrosion current is gradually increasing by long-term monitoring. Progress can also be identified.

  For example, as shown in FIG. 4, when the anticorrosion current of the station A and the station B gradually increases due to the data management of several months and years, the minute damage due to the contact of other structures between the stations B-C. If this is left unattended, there is a concern that such damage will gradually expand.

  By adopting the management form as described above, the conduit manager can perform investigation and countermeasures by limiting the anticorrosion failure section in the short term and the long term.

  FIG. 5 shows the configuration of the anticorrosion state monitoring system 11 that monitors the anticorrosion state over time via the communication network 7.

  In this anticorrosion state monitoring system 11, in the gas conduit 3 having an insulation section of 18 km, the stationary DC current measuring device 1 is mounted on the exposed conduit for each station A to E. The direct current measuring device 1 converts the measured value of the anticorrosive current and the direction in which the anticorrosive current flows, and transmits this data to the conduit manager receiver 8 via the communication network 7. The DC current measuring device 1 may be provided with the same function as that of a normal PC (personal computer), and may be configured to transfer data in response to a transmission request transmitted via the communication network 7. Alternatively, such data may be periodically transferred based on a control program stored in its own ROM (not shown).

  In addition, the direct current measuring device 1 is equipped with a communication I / F (not shown) for executing wired or wireless communication with the communication network 7. The communication I / F (not shown) is realized by a line control circuit for connecting to the communication network 7 and a modem as a signal conversion device for performing data communication. The communication I / F (not shown) performs conversion processing on various commands from the control unit of the DC current measuring device 1 and sends it to the communication network 7 side, and receives data from the communication network 7. This is subjected to a predetermined conversion process.

  The communication network 7 is connected to a TA / modem including an Internet network connected via a telephone line between the DC current measuring device 1 and the conduit manager receiver 8 arranged in each station A to E. ISDN (Integrated Services Digital Network) / B (broadband) -ISDN or the like, and is configured by a public communication network or the like that enables bidirectional transmission and reception of information.

  The conduit manager receiver 8 is composed of a PC or the like, acquires the corrosion protection current measurement value transmitted from each DC current measuring device 1 via the communication network 7 and the data of the direction in which the corrosion protection current flows, and displays the data. It is displayed to the conduit manager via the network and is made into a database. When data is continuously acquired, current information periodically transmitted from each DC current measuring device 1 is stored in a hard disk (not shown), and these are checked afterwards for a long time. Monitoring can be realized.

  In this anticorrosion state monitoring system 11, the conduit manager can always monitor the amount of anticorrosion current and the flowing direction in real time without going around the stations A to E, and can easily carry out daily anticorrosion state monitoring work. Become. Moreover, it is possible to grasp the corrosion prevention status of the entire conduit at a stroke.

  Here, if a civil engineering heavy machinery 6 contact accident occurs in the conduit of the monitoring section and the coating is destroyed and the anticorrosive current flows into the damaged part, the anticorrosive current value at the station from the damaged part to the external power source increases. The occurrence of damage is determined by detecting an increase in the anticorrosion current. The anticorrosion current distribution is the same as that shown in FIG. Further, in this anticorrosion state monitoring system 11, since the change in the anticorrosion current of each station A to E can be monitored in real time, the anticorrosion current of each station A to E is on the order of several hours to several minutes as shown in FIG. It is also possible to identify changes in

In between this figure in 6 is damaged upon occurrence t ₁ at station B and station C, shows a case where damage protection current Id flows occurs.

The conduit manager sets a threshold value (indicated by a one-dot broken line in FIG. 6) for the increase / decrease of the anticorrosion current value measured at each of the stations A to E. Then, it is determined that such damage has occurred at the time when the threshold value is exceeded with respect to the anticorrosion current value measured in real time in each of the stations A to E (in this case, at the time of damage occurrence t ₁ ). The conduit manager receiver 8 may be alerted to the conduit manager by incorporating a mechanism that issues an alarm when it is determined that such damage has occurred.

  Further, in the estimation of the damage point shown in FIG. 6, the current values of the stations A and B increase and exceed the threshold value, but the other stations C to E do not exceed the threshold value. It is possible to determine that a problem has occurred in. For this reason, the conduit manager patrols between stations B and C at the time when an alarm is issued, and investigates whether there is any abnormality.

  In this way, the anticorrosion state monitoring system 11 can notify the administrator of the abnormality of the gas conduit 3 in real time, so that it is possible to take measures to prevent the damage from spreading and recover immediately. It is possible to eliminate the cause of adding, and thus to prevent a fatal accident.

  In addition, in the anticorrosion state monitoring systems 10 and 11, an induced current induced in the gas conduit 3 can be measured by adding an AC measuring device (not shown). For this reason, in addition to measuring the direct current anticorrosive current, conduits running alongside the high voltage power transmission line can measure the current component of the commercial frequency to grasp the induced current, and can also investigate the alternating current corrosion.

  FIG. 7 shows a configuration of the anticorrosion state monitoring system 12 that monitors the anticorrosion state over time via the communication network 7.

  In this anticorrosion state monitoring system 12, the stationary DC current measuring device 1 is mounted on the exposed conduits in the stations A to E in the gas conduit 3 having an insulation section of 18 km. In addition, an operation example in the case where two external power supply devices 4a and 4b for preventing corrosion in this section are arranged at both ends of the insulating section is shown.

  FIG. 8 shows the anticorrosion current at each of the stations A to E measured by the anticorrosion state monitoring system 12. In FIG. 8, the direct current of the circuit formed by the external power supply 4a in each station A to E is plotted as positive, and the direct current of the circuit formed by the external power supply 4b is plotted as negative. In the C station near the center, the influences of the external power sources 4a and 4b at both ends are antagonized, and the anticorrosion current is measured as a small value.

  In FIG. 8, the coating of a large-scale other structure (for example, a reinforcing bar of a large-scale concrete structure) between stations B and C is broken due to an earthquake, etc., and a metal touch is caused to cause a corrosion-proof current to the other structure. The current distribution when a large amount of flows in is shown by dotted lines.

  In such a case, in the stations A and E and the stations B and D at both ends, the direction in which the measured anticorrosion current flows does not change, and an increase or decrease in the current amount is observed. Further, in the station C, the flow direction of the anticorrosion current is reversed, and the electric circuit formed by the external power supply 4a is shifted to the electric circuit formed by the external power supply 4b.

FIG. 9 shows the change over time of the anticorrosion current in each of the stations A to E measured by the anticorrosion state monitoring system 12. Damage in damage occurring during t ₁ in the same manner as corrosion condition monitoring system 11 described above can be detected that has occurred.

  That is, if the conventional determination method is applied to the conventional damage section determination method shown in Examples 1 and 2, it can be determined that there is damage downstream of the anticorrosion current as viewed from the measurement point. It can be determined that an abnormality has occurred between the stations B-C.

  In this way, the current direction (that is, the determination of the power supply direction) that could not be performed by the conventional current transformer for alternating current can also be performed by this technology. As shown in this example, damage occurs even when a plurality of anticorrosive current supply sources coexist. And the occurrence interval can be detected.

  That is, the present invention provides a direct current measuring technique for measuring the anticorrosive current, which is difficult to directly measure, in addition to the conventional anticorrosive potential management, the anticorrosive current inflow density management by the probe, and the output control of the external power supply, and the like. By introducing it, it is possible to provide an effective and reliable method for managing the anticorrosion state.

  In the present invention, the anti-corrosion function that suddenly generates coating monitoring of the anti-corrosion section, which has been conventionally performed with an AC signal by monitoring the anti-corrosion current over the entire line in real time, without the installation of equipment such as an AC power supply or a signal measuring device. It is possible to deal with accidents that can be damaged. Furthermore, it is possible to detect the corrosion prevention condition that gradually deteriorates by long-term monitoring, and it is possible to take an appropriate response based on this, and it is possible to improve the efficiency and reliability of conduit maintenance management.

  Further, in the present invention, the conduit manager receiver 8 may access the external power supply 4a via the communication network 7 and control the amount of anticorrosion current to be flowed from there. At this time, when it is determined that there is a problem with the coating, the conduit manager receiver 8 accesses the external power supply device via the communication network 7 and instructs to increase the amount of anticorrosion current to be passed. You may do it. In such a case, a communication function is mounted on the external power supply 4a.

In addition, since the defect part obtained by the present invention is an approximate position between certain measurement points, when specifying an accurate position, in the section where the existence of the defect is recognized, for example, the above-mentioned Japanese Patent Publication No. 7-52166. The detailed position may be determined by using the technique disclosed in the above.

Further, when used together with conventional potential distribution monitoring, the resistance value of the coating can be calculated from the anticorrosion current value and the anticorrosion potential value, and quantitative evaluation becomes possible. Incidentally, for this anticorrosion potential, for example, a conventional anticorrosion potential measuring device may be used. The corrosion resistance value at each point, the conventional anticorrosion potential record, and the coating resistance value calculated from these values are monitored over a long period, converted into data, and the change is estimated to estimate the progress of coating deterioration. However, measures can be taken for sections where deterioration progresses quickly.

1 is an overall view showing an embodiment of the present invention. It is a figure which shows the anticorrosion current measurement result in each station. It is a figure which shows the electric current distribution measured in each station in case the insulation performance of an insulation coupling is defect. It is a figure which shows the anti-corrosion current change at the time of the malfunction of a long-term coating coating progressing. It is a figure which shows other embodiment of this invention. B at time t _1, per If damage occurs between C, illustrates in time series. It is a figure which shows other embodiment of this invention. It is a figure which shows the anticorrosion current measurement result in each station in embodiment shown in FIG. In the embodiment shown in FIG. 7, it is the figure shown in time series about the case where damage generate | occur | produced between B and C. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC current measuring device 2 Monitoring person 3 Gas conduit 4 External power supply device 5 Insulation joint 6 Civil engineering machinery 7 Communication network 8 Conduit manager receiver 10, 11, 12 Corrosion prevention state monitoring system

Claims (11)

In the anticorrosion state monitoring method for monitoring the anticorrosion state of the buried metal subjected to coating and electrocorrosion protection,
Attach a DC measuring device sensor unit that measures the magnitude and direction of the anticorrosion current of the buried metal in a non-contact manner at least at one measurement point so that the magnetic path is linked to the anticorrosion current,
Identify the amount of anticorrosive current measured by the DC measuring device and the direction of flow,
While determining the direct current measurement value based on the current amount and the flowing direction of the identified anticorrosion current, and further determining the anticorrosion potential by the anticorrosion potential measuring device,
An anticorrosion state monitoring method characterized in that the anticorrosion state of coating and buried metal is evaluated based on the determined anticorrosion potential and DC current measurement value. It is characterized by continuously monitoring the amount of anticorrosive current and the direction of flow, and if an increase in the anticorrosive current is detected, it is determined that there is a defect such as damage to the coating in the downstream (insulating end) direction of the anticorrosive current. The anticorrosion state monitoring method according to claim 1. In the anticorrosion system in which the anticorrosion power supply is performed at one discharge point in the same insulation section, the anticorrosion current is measured by attaching a DC measuring device at at least two measurement points, and the current between the above measurement points. Calculate the difference in quantity, and if the downstream (insulation end) current is attenuated more than the reference value with respect to the upstream (power supply) side current value, determine that the coating between the measurement points is defective. The anticorrosion state monitoring method according to claim 1. 4. The anticorrosion state monitoring method according to claim 2, wherein the determination as to whether or not there is a defect in coating is performed by a control device connected to the current measuring device via a communication network. . When it is determined by the control device that there is a problem with coating, the external power supply device through which the anticorrosive current is supplied is accessed via the communication network, and the amount of anticorrosive current to be supplied is controlled. The anticorrosion state monitoring method according to claim 4. The anticorrosion state monitoring method according to claim 1, wherein a DC measuring device is mounted in the vicinity of the insulating joint and the insulating performance of the insulating joint is investigated. 2. It is determined that there is an abnormality in the downstream direction of the current when the current direction of the anticorrosion current is reversed or reduced in the section where the anticorrosion is performed by two or more anticorrosive power sources. Anti-corrosion status monitoring method. In the anti-corrosion state monitoring system for monitoring the anti-corrosion state of the buried metal that has been coated and electrically protected,
A direct current measuring device that measures the magnitude and direction of the anticorrosion current of the buried metal in a non-contact manner at least at one measurement point;
An anti-corrosion potential measuring device for determining the anti-corrosion potential;
A controller that identifies the amount and direction of the anticorrosive current measured by the DC measuring device via a communication network, and obtains the anticorrosive potential determined by the anticorrosive potential measuring device via the communication network. ,
The control device determines a direct current measurement value based on the current amount and the flowing direction of the identified anticorrosion current, and based on the determined direct current measurement value and the acquired anticorrosion potential, An anti-corrosion state monitoring system characterized by evaluating the anti-corrosion state of buried metal. In the anticorrosion system where the anticorrosion power supply is performed at one discharge point in the same insulation section, the control device continuously monitors the amount and direction of the anticorrosion current and detects an increase in the anticorrosion current. 9. The anticorrosion state monitoring system according to claim 8, wherein it is determined that there is a defect such as damage to the coating in the downstream (insulation end) direction of the anticorrosion current. In the anti-corrosion system where the anti-corrosion power supply is performed at one discharge point in the same insulation section, the DC measurement device is mounted at at least two measurement points,
The control device calculates the difference in current amount between the measurement points, and when the downstream (insulation end) current is attenuated by more than the reference value with respect to the upstream (power supply) side current value, the measurement point The anticorrosion state monitoring system according to claim 8, wherein it is determined that there is a defect in the coating of the anticorrosion. When the control device determines that there is a problem with the coating, the control device accesses the external power supply device through which the anticorrosion current flows through the communication network, and controls the amount of anticorrosion current to be supplied. The anticorrosion state monitoring system according to any one of claims 8 to 10.

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