JP2021148433A - Corrosion management system - Google Patents

Abstract

To provide a corrosion management system capable of predicting and managing the remaining life of pipes with high accuracy, for example, by separating a corrosion incubation period and corrosion progress period and identifying the time of occurrence of local corrosion.SOLUTION: A disclosed corrosion management system includes: a resistance component monitoring sensor that monitors electrical resistance components in a corrosive environment; a driving force component monitoring sensor that monitors a driving force component that promotes corrosion in a corrosive environment; a data storage unit that stores data output from the resistance component monitoring sensor and the driving force component monitoring sensor; and a corrosion risk determination unit that identifies the time of occurrence of local corrosion using the data in the data storage unit, sets the corrosion growth rate and determines the corrosion risk.SELECTED DRAWING: Figure 1

Description

The present invention relates to a corrosion management system.

For example, some plant equipment such as pipes and infrastructure equipment are covered with an external environment such as heat insulating material and buried soil, and the state of pipes and the like cannot be directly and visually confirmed. Therefore, in order to inspect pipes and the like, it is necessary to remove these external environments and inspect the corrosive state of the pipes and the like, or install a sensor to determine the corrosive state of the pipes and the like. In particular, some sensors monitor parameters related to the corrosiveness of a corrosive environment (hereinafter sometimes referred to as "environmental factors"), and some sensors directly measure the amount of corrosion of pipes and the like.

As a background technique in this technical field, there is Japanese Patent Application Laid-Open No. 2007-278843 (Patent Document 1). Patent Document 1 is a corrosion diagnostic device for diagnosing corrosion of a steel underground steel structure whose outer surface is covered with a predetermined material and which is buried in the ground. An impedance measuring means for measuring the electrochemical impedance between the ground electrode connected to the structure and an electrical corrosion environment measuring means for measuring the electrical corrosion environment around the underground steel structure. , A corrosion diagnostic apparatus having a determination means for determining a corrosion state of an underground steel structure based on the results obtained by an impedance measuring means and an electrical corrosion environment measuring means is described (see summary).

Further, as a background technique in this technical field, there is Japanese Patent Application Laid-Open No. 2019-056681 (Patent Document 2). Patent Document 2 describes a potential sensor that measures the potential of a solution in the vicinity of an object, a storage unit that stores the measured potential in a time series, and corrosion of the object according to the stored time-series potential. A corrosion prediction system that has a decision-making part that determines the future form of the object that changes with the progress of the object and that grasps the progress of corrosion that is actually occurring in the object is described (see summary). ).

JP-A-2007-278843 Japanese Unexamined Patent Publication No. 2019-056681

Patent Document 1 describes a corrosion diagnostic apparatus having a determination means for determining a corrosion state of an underground steel structure. Further, Patent Document 2 describes a corrosion prediction system having a determination unit for determining a future form of an object that changes as the corrosion of the object progresses. The corrosion diagnostic apparatus described in Patent Document 1 and the corrosion prediction system described in Patent Document 2 relate to detection of total corrosion.

Total corrosion basically progresses at the same time as the start of use of pipes and the like. On the other hand, local corrosion represented by pitting corrosion and crevice corrosion has a certain corrosion incubation period.

Patent Document 1 and Patent Document 2 do not describe a corrosion control system for detecting local corrosion, and the corrosion diagnostic apparatus described in Patent Document 1 and the corrosion prediction system described in Patent Document 2 detect local corrosion. May not be used.

Therefore, in order to detect local corrosion, the present invention classifies the corrosion incubation period and the corrosion progress period, specifies the corrosion occurrence time of local corrosion, and predicts and manages the remaining life of pipes, for example, with high accuracy. To provide a corrosion control system.

In order to solve the above-mentioned problems, the corrosion management system of the present invention has a resistance component monitoring sensor that monitors the electrical resistance component of the corrosive environment and a driving force component monitoring that monitors the driving force component that promotes corrosion in the corroded environment. Using the data of the sensor, the data recording device that records the data output by the resistance component monitoring sensor and the driving force component monitoring sensor, and the data of the data recording device, identify the corrosion occurrence time of local corrosion and set the corrosion progress rate. It is characterized by having a corrosion risk determination device for determining a corrosion risk.

According to the present invention, in order to detect local corrosion, the corrosion incubation period and the corrosion progress period are separated, the corrosion occurrence time of local corrosion is specified, and the remaining life of, for example, piping is predicted and managed with high accuracy. Corrosion control system can be provided.

Issues, configurations, and effects other than those described above will be clarified by the explanation of the examples below.

It is explanatory drawing which schematically explains the corrosion management system 100 described in Example 1. FIG. It is a flow figure explaining the determination procedure of the corrosion risk described in Example 1. FIG. It is explanatory drawing explaining the time change of the corrosion amount of the monitoring object (piping) 101 described in Example 1. FIG. It is a flow figure explaining the re-determination after maintenance execution which is described in Example 1. FIG. It is explanatory drawing explaining (A) the measurement result of the electric conductivity with respect to time, and (B) the measurement result of pH with respect to time which is described in Example 1. FIG. It is explanatory drawing which schematically explains the corrosion management system 200 described in Example 2. FIG. It is a flow figure explaining the determination procedure of the corrosion risk described in Example 2. FIG. It is explanatory drawing explaining the measurement result of the material potential with respect to time described in Example 2. It is explanatory drawing which schematically explains the corrosion management system 300 described in Example 3. FIG. FIG. 5 is a flow chart illustrating a procedure for determining a corrosion risk described in Example 3. It is explanatory drawing explaining the measurement result of the corrosion current and the water content with respect to the time described in Example 3. FIG. It is explanatory drawing which schematically explains the corrosion management system 400 described in Example 4. FIG. FIG. 5 is a flow chart illustrating a procedure for determining a corrosion risk described in Example 4. It is explanatory drawing explaining the measurement result of the current density with respect to time described in Example 4. FIG.

Hereinafter, examples of the present invention will be described with reference to the drawings. The substantially same or similar configurations are designated by the same reference numerals, and when the explanations are duplicated, the explanations may be omitted.

First, the corrosion management system 100 described in the first embodiment will be schematically described.

FIG. 1 is an explanatory diagram schematically explaining the corrosion management system 100 described in the first embodiment.

The corrosion management system 100 described in the first embodiment determines the corrosiveness of, for example, the corrosive environment (monitored environment) 102 such as seawater that circulates on the inner surface side (inside) of the monitored object 101 such as piping. This is a system that detects local corrosion of the monitored object 101 (determines the corrosion state of the monitored object 101) and predicts and manages the remaining life of the monitored object 101.

The corrosion management system 100 is a sensor that monitors the electrical resistance component of the corrosion environment 102, the resistance component monitoring sensor 103 that detects the occurrence of corrosion, and the sensor that monitors the driving force component that promotes the corrosion of the corrosion environment 102. The data of the driving force component monitoring sensor 104 that captures the progress of corrosion, the data recording device 105 that records the data output by the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104, and the data of the data recording device 105 are used. It also has a corrosion risk determining device 106 for determining the corrosion risk of the monitored object 101.

In the first embodiment, the monitored object 101 is a metal (austenitic stainless steel: SUS316L) pipe. Hereinafter, the monitoring target object 101 will be described as the piping 101.

Then, in order to detect local corrosion inside the pipe 101, a plurality of resistance component monitoring sensors 103 and driving force component monitoring sensors 104 are installed at a plurality of locations. The resistance component monitoring sensor 103 and the driving force component monitoring sensor 104 are preferably installed as a sensor set at close positions such as inside the same seat 107 of the pipe 101.

That is, the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104 monitor (measure) the resistance component and the driving force component at the same point to monitor the corrosiveness of the corrosive environment 102 at the same point. ..

The resistance component monitoring sensor 103 measures an environmental factor that is an electrical resistance component of the corrosive environment 102. The environmental factors to be measured are, for example, electrical conductivity, water content, humidity, water content, resistivity, and the like, and are environmental factors that serve as resistance components when the corrosive environment 102 becomes an electrical conduction path. The resistance component includes a component related to moisture such as humidity, water content, and water content, and a component related to electric resistance such as electric conductivity and resistivity.

The driving force component monitoring sensor 104 measures the environmental factor of the corrosive environment 102, which is a driving force component that promotes corrosion. The environmental factors to be measured include, for example, environmental factors that indicate the acidity of the corrosive environment 102 such as pH (hydrogen ion concentration) and acid equivalent, and the oxidizing power of the corrosive environment 102 such as ORP (oxidation-reduction potential). It is an environmental factor. The driving force component includes a component related to acidity such as pH and acid equivalent amount, and a component related to oxidizing power such as ORP.

Further, the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104 are installed at a plurality of locations so as to have a predetermined interval (for example, 1 m interval) with respect to the pipe 101 and to have a position resolution. Is preferable. Environmental factors in the portion where the sensor (103 or 104) is not installed (the portion between the sensors) are predicted by the corrosion risk determination device 106. For example, the environmental factor of the part between the sensors is predicted to change linearly, and the environmental factor of the part between the sensors is predicted.

Further, the interval at which the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104 measure environmental factors is preferably as short as, for example, 10 seconds, but even if the interval is one day such as daily inspection, the environment If the fluctuation (change in corrosiveness of the corrosive environment 102) can be grasped, there is no problem.

The data recording device 105 records the data measured by the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104. The data recording device 105 may be, for example, an electrochemical measuring device such as a potentiostat.

The corrosion risk determination device 106 uses the data recorded in the data recording device 105 to determine the corrosion risk of the pipe 101.

Next, the procedure for determining the corrosion risk described in Example 1 will be described.

FIG. 2 is a flow chart illustrating the procedure for determining the corrosion risk described in the first embodiment.

In the first embodiment, the resistance component monitoring sensor 103 monitors the electrical conductivity, and the driving force component monitoring sensor 104 monitors the pH. In Example 1, the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104 measure a single environmental factor, but in order to further accurately determine the corrosion risk, a plurality of environmental factors are used. It is preferable to measure.

Hereinafter, the procedure for determining the corrosion risk described in Example 1 will be sequentially described.

(1) The resistance component monitoring sensor 103 measures the electrical conductivity (S101).

(2) The driving force component monitoring sensor 104 measures the pH (S102).

(3) The corrosion risk determination device 106 determines the corrosion risk by using the data measured by the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104 and recorded in the data recording device 105.

(3-1) First, the corrosion risk determination device 106 determines whether or not corrosion has occurred (S103). In Example 1, the presence or absence of corrosion is determined based on the electrical conductivity and pH.

To determine the presence or absence of corrosion, the material type of the pipe 101 (SUS316L in Example 1), the construction form such as the presence or absence of welding (no welding in Example 1), and the type of fluid flowing through the pipe 101 (Example 1). Then seawater) is used as basic information. Then, it is determined whether or not the environmental factor to be measured exceeds a predetermined threshold value (whether or not it reaches a predetermined threshold value).

The threshold value for electrical conductivity is set by grasping in advance the correlation between the salt concentration of seawater related to electrical conductivity and the occurrence of corrosion by experiments or the like. In Example 1, the threshold value for electrical conductivity was set to 50 mS / cm.

As the threshold value for pH, the depassivation pH determined by the material type is set as the threshold value for corrosion occurrence. In Example 1, the pH threshold was set to 4, which is the depassivation pH of SUS316L.

In this way, when the electrical conductivity reaches 50 mS / cm and the pH reaches 4, it is determined that corrosion has occurred. That is, whether or not the local (at the position where one sensor set is installed) environmental factor of the resistance component and the environmental factor of the driving force component at the same point exceeds a predetermined threshold value (reaches a predetermined threshold value). Whether or not) is used to determine whether or not corrosion has occurred locally.

The environmental factor used to determine the presence or absence of corrosion is not limited to electrical conductivity and pH, and may be any environmental factor that causes local corrosion. In addition, the experimental results in the laboratory are used to determine the presence or absence of corrosion, and the accumulated operation data and operation data related to the occurrence of corrosion are mathematically analyzed by, for example, machine learning or simulation. Analysis data and the like may be used.

(3-2) Next, the corrosion risk determination device 106 determines the presence or absence of corrosion progress (S104). In Example 1, the presence or absence of corrosion progress is determined based on the electrical conductivity and pH.

In order to determine the presence or absence of corrosion progress, the material type of the pipe 101 (SUS316L in Example 1), the construction form such as the presence or absence of welding (no welding in Example 1), and the type of fluid flowing through the pipe 101 (Example 1). Then seawater) is used as basic information. Then, it is determined whether or not the environmental factor to be measured exceeds a predetermined threshold value (whether or not it reaches a predetermined threshold value).

The threshold value for electrical conductivity is set by grasping in advance the correlation between the salt concentration of seawater related to electrical conductivity and the occurrence of corrosion by experiments or the like. In Example 1, the threshold value for electrical conductivity was set to 50 mS / cm.

The threshold value related to pH is grasped and set in advance by experiments or the like. In Example 1, the pH threshold was set to 8.

In this way, when the electrical conductivity reaches 50 mS / cm again after the occurrence of corrosion and the pH reaches 8 again after the occurrence of corrosion, it is determined that the corrosion progresses “presence”. That is, depending on whether or not the local environmental factor of the resistance component and the environmental factor of the driving force component at the same point exceed the predetermined threshold value (whether or not the predetermined threshold value is reached), the local environmental factor. Determine if corrosion has progressed.

The environmental factor used to determine the presence or absence of corrosion progress is not limited to electrical conductivity and pH, and may be any environmental factor that promotes local corrosion. In addition, experimental results in the laboratory are used to determine the presence or absence of corrosion progress, and the accumulated operation data and operation data related to corrosion progress are mathematically analyzed by, for example, machine learning or simulation. Analysis data and the like may be used.

In particular, in order to determine the presence or absence of corrosion progress, it is important whether or not the pipe 101 is re-immobilized and local corrosion is stopped, and the experimental results (pH 8 in Example 1) grasped by experiments and the like are used. NS.

(3-3) Next, the corrosion risk determination device 106 determines (sets) the corrosion progress rate (S105). In the first embodiment, the corrosion progress rate is set in response to the determination result of “presence” of corrosion occurrence determined in S103 and the determination result of “presence” of corrosion progress determined in S104.

The corrosion progress rate is set by grasping in advance the time change of the amount of corrosion of the pipe 101 in the corrosiveness of the predetermined corrosive environment 102 with respect to the basic information of one pipe 101 by experiments or the like.

For example, as the basic information of the pipe 101, the material type is SUS316L, the construction form is no welding, and the type of fluid flowing through the pipe 101 is seawater. Then, the corrosiveness of the corrosive environment 102 is defined as, for example, the salt concentration of seawater when seawater flows through the unwelded pipe 101 of SUS316L. That is, the time change of the amount of corrosion of the unwelded pipe 101 of SUS316L at a predetermined seawater salt concentration is grasped. Thereby, the corrosion progress rate can be set.

In addition, experimental results in the laboratory are used to set the corrosion progress rate, and the accumulated operation data and operation data related to the corrosion progress rate are mathematically analyzed by, for example, machine learning or simulation. Analysis data and the like may be used.

As described above, for local corrosion, the corrosion occurrence time at which the corrosion incubation period (the period until the corrosion occurs) and the corrosion progress period (the period during which the corrosion progresses) is switched is important, and the corrosion progress rate is the corrosion environment 102. It is greatly affected by the corrosiveness of.

(3-4) Finally, the corrosion risk determination device 106 determines the corrosion risk (S106). In the first embodiment, the corrosion risk is increased by receiving the determination result of corrosion occurrence “presence” determined in S103, the determination result of corrosion progress “presence” determined in S104, and the corrosion progress rate set in S105. judge. The corrosion risk is determined whether or not the pipe 101 reaches the corrosion allowable limit value.

Then, the corrosion risk is determined based on design information such as corrosion occurrence time, corrosion progress rate, corrosion allowance of pipe 101, and operation information such as usage time of pipe 101. The remaining life of the pipe 101 is expected based on the risk of corrosion. Thereby, it is possible to propose the replacement time of the pipe 101 and the like.

Here, the time change of the amount of corrosion of the pipe 101 described in the first embodiment will be described.

FIG. 3 is an explanatory diagram for explaining the time change of the amount of corrosion of the pipe 101 described in the first embodiment.

In FIG. 3, the horizontal axis represents the usage time of the pipe 101, and the vertical axis represents the amount of corrosion of the pipe 101. In general, the total corrosion progresses on the entire surface at the same time as the start of use of the pipe 101. That is, there is no corrosion incubation period for total corrosion. On the other hand, local corrosion has a certain corrosion incubation period. In the first embodiment, the period from the start of use of the pipe 101 to the determination of “presence” of corrosion occurrence corresponds to the corrosion incubation period, and the period after the corrosion occurrence period corresponds to the corrosion progress period.

As shown in FIG. 3, local corrosion has a faster corrosion progress rate than total corrosion. That is, the local corrosion may reach the corrosion allowable limit value set based on the design information of the pipe 101 and the operation information of the pipe 101 faster than the total corrosion.

For example, even if the basic information of the pipe 101 is the same, the corrosion progress rate (inclination) changes when the salt concentration of the seawater flowing through the pipe 101 changes. That is, the time until the pipe 101 reaches the corrosion allowable limit value changes. That is, in the first embodiment, the time when the local corrosion occurs can be specified, and the time until the pipe 101 reaches the allowable corrosion limit value can be predicted with high accuracy according to the corrosiveness of the corrosive environment 102. ..

Further, the corrosion allowable limit value of the pipe 101 also changes according to the design information of the pipe 101 and the operation information of the pipe 101. That is, in the first embodiment, by setting the corrosion allowable limit value of the pipe 101 based on the design information of the pipe 101 and the operation information of the pipe 101, the time until the pipe 101 reaches the corrosion allowable limit value is set. It can be predicted with high accuracy.

In addition, by separating the presence / absence of corrosion occurrence, the presence / absence of corrosion progress, and the setting of the corrosion progress rate, it is possible to distinguish between the corrosion incubation period and the corrosion progress period, and the influence of environmental factors can be predicted with high accuracy. ..

In this way, by separating the corrosion incubation period and the corrosion progress period, the time when the corrosion of local corrosion occurs is specified, and the remaining life of the pipe 101 (the time until the pipe 101 reaches the allowable corrosion limit value) is determined. It can be predicted with high accuracy.

Further, in the corrosion management system 100 described in the first embodiment, the replacement work of the pipe 101 includes the remaining life of the pipe 101 (replacement time of the pipe 101), the arrangement period of the replacement pipe 101, and the securing period of the worker. By showing the likelihood of the period until the completion of the above, the pipe 101 can be totally managed.

Further, the corrosion management system 100 can be used to monitor the pipe 101, diagnose (determine) the corrosion state of the pipe 101, and propose the maintenance time (replacement time) of the pipe 101. In this way, the corrosion management system 100 can provide a monitoring / diagnosis / maintenance service that comprehensively performs monitoring, diagnosis, and maintenance, and the piping 101 can be used as safely as possible.

Next, the re-determination after the maintenance described in the first embodiment will be described.

FIG. 4 is a flow chart for explaining the re-determination after the maintenance implementation described in the first embodiment.

The corroded state of the pipe 101 is diagnosed, and the maintenance (replacement) of the pipe 101 is carried out based on this diagnosis (S111).

When the maintenance (replacement) of the pipe 101 is performed, the deterioration state of the pipe 101 (the state of the maintenance (replacement) pipe 101 and the maintenance (replacement) pipe 101) is measured in order to predict the corrosion risk with high accuracy. (S112). For example, the wall thickness of the pipe 101 to be maintained (replaced) is measured, and the amount of thinning of the pipe 101 to be maintained (replaced) is measured.

Then, by maintenance (replacement), the design information of the pipe 101 and the operation information of the pipe 101 are appropriately corrected (S113), and the corrosion occurrence time and the corrosion progress rate are determined again. That is, the design information of the pipe 101 and the operation information of the pipe 101 are initialized.

In addition, if parameters related to corrosion such as the amount of wall loss of the pipe 101 measured during maintenance (replacement) can be measured, the measured values can be used to correct the coefficient of corrosion progress rate. can.

After that, the resistance component monitoring sensor 103 and the driving force component monitoring sensor 104 measure, and the data recorded in the data recording device 105 is used to determine the corrosion risk.

That is, after performing maintenance (replacement) of the pipe 101, the corrosion risk determination device 106 again identifies the corrosion occurrence time of local corrosion, sets the corrosion progress rate, and determines the corrosion risk.

In this way, the corrosion management system 100 can perform total monitoring, diagnosis, and maintenance, and after the maintenance is performed, the piping 101 can be monitored, diagnosed, and maintained again with higher accuracy. Can be done.

Next, the measurement result of the electric conductivity with respect to the time (A) and the measurement result of the pH with respect to the time (B) described in Example 1 will be described.

FIG. 5 is an explanatory diagram for explaining (A) the measurement result of electrical conductivity with respect to time and (B) the measurement result of pH with respect to time, which is described in Example 1.

FIG. 5 shows the measurement results obtained by simultaneously measuring (A) the change in electrical conductivity with respect to time (day) and (B) the change in pH with respect to time (day) in the basic information of the pipe 101.

About 200 days after the start of the measurement, the electrical conductivity reached 50 mS / cm, and about 200 days after the start of the measurement, the pH reached 4. As a result, it can be determined that corrosion has occurred. Further, about 275 days after the occurrence of corrosion, the electrical conductivity reached 50 mS / cm again, and about 235 days after the occurrence of corrosion, the pH reached 8 again. As a result, it can be determined that the corrosion progress is “presence”.

In this way, by continuously measuring the electrical conductivity and the pH, it is possible to determine the presence or absence of corrosion progress after the occurrence of corrosion.

The corrosion management system 100 described in the first embodiment includes a resistance component monitoring sensor 103 that monitors the electrical resistance component of the corrosion environment 102 and a driving force component monitoring sensor that monitors the driving force component that promotes the corrosion of the corrosion environment 102. Using the data of the data recording device 105 that records the data output by the 104, the resistance component monitoring sensor 103, and the driving force component monitoring sensor 104, and the data recording device 105, the corrosion occurrence time of local corrosion is specified, and corrosion occurs. It has a corrosion risk determination device 106 that sets the propagation speed and determines the corrosion risk.

According to the first embodiment, in order to detect the local corrosion, the corrosion latent period and the corrosion progress period are classified, and the corrosion occurrence time of the local corrosion is specified. For example, whether or not the pipe 101 reaches the corrosion allowable limit value. It is possible to provide a corrosion management system 100 that determines the corrosion risk and accurately predicts the remaining life of the pipe 101, which is the time until the pipe 101 reaches the allowable corrosion limit value.

Next, the corrosion management system 200 described in the second embodiment will be schematically described.

FIG. 6 is an explanatory diagram schematically explaining the corrosion management system 200 described in the second embodiment.

The corrosion control system 200 described in the second embodiment has a corrosion resistance (or a corrosion progress rate of the material) of the material inside the same seat 107 of the pipe 101 as compared with the corrosion control system 100 described in the first embodiment. The difference is that the target corrosion rate monitoring sensor 111 to be monitored is additionally installed.

The target corrosion rate monitoring sensor 111 is made of the same material as the pipe 101, and a sensor that pseudo-measures the amount of corrosion of the pipe 101, for example, a corrosion amount monitoring coupon (test piece), and data for setting the corrosion progress rate are used. A sensor for measuring, for example, a sensor for measuring a corrosion current of the same material as the pipe 101, a sensor for measuring a material potential in electrochemistry of the same material as the pipe 101, and the like. In the second embodiment, a sensor for measuring the material potential is used.

In the first embodiment, the corrosion progress rate is set and the corrosion risk is determined based on the determination result of the corrosion occurrence “presence” determined in S103 and the determination result of the corrosion progress “presence” determined in S104. do. That is, the corrosion risk is determined based on the corrosiveness of the corrosive environment 102.

On the other hand, in the second embodiment, the determination result of the corrosion occurrence “presence” determined in S103, the determination result of the corrosion progress “presence” determined in S104, and the material potential measured in S107 are received. Determine the risk of corrosion. That is, the corrosion risk is determined based on the corrosion state of the pipe 101. As described above, in the second embodiment, the corrosion risk is determined with high accuracy by monitoring the environmental factors and the material factors.

Then, in the second embodiment, by installing the target corrosion rate monitoring sensor 111, the corrosion state of the pipe 101 due to the environmental change is directly determined. That is, the corrosion form can be predicted with high accuracy by simultaneously grasping the change of the environmental factor and the change of the material factor and determining the corrosion state of the pipe 101.

Next, the procedure for determining the corrosion risk described in Example 2 will be described.

FIG. 7 is a flow chart illustrating the procedure for determining the corrosion risk described in the second embodiment.

In the second embodiment, the resistance component monitoring sensor 103 monitors the electrical conductivity, the driving force component monitoring sensor 104 monitors the pH, and the target corrosion rate monitoring sensor 111 monitors the material potential.

Hereinafter, the procedure for determining the corrosion risk described in Example 2 will be described based on the difference from Example 1.

(1) The resistance component monitoring sensor 103 measures the electrical conductivity (S101).

(2) The driving force component monitoring sensor 104 measures the pH (S102).

(3) The target corrosion rate monitoring sensor 111 measures the material potential (S107). That is, by measuring the material potential, for example, a stable film of a material such as a passivation film is dissolved in response to environmental changes, active dissolution is started, and the corrosion occurrence time of local corrosion can be specified. ..

(4) The corrosion risk determination device 106 measures the resistance component monitoring sensor 103, the driving force component monitoring sensor 104, and the target corrosion rate monitoring sensor 111, and uses the data recorded in the data recording device 105 to determine the corrosion risk. judge.

(4-1) The corrosion risk determination device 106 receives the material potential measured in S107, identifies the corrosion occurrence time of local corrosion, and sets the corrosion progress rate (S105). In Example 2, the corrosion progress rate is based on the determination result of corrosion occurrence “presence” determined in S103, the determination result of corrosion progress “presence” determined in S104, and the corrosion occurrence time of local corrosion. To set.

(4-2) Finally, the corrosion risk determination device 106 determines the corrosion risk (S106). In the second embodiment, the corrosion risk is increased by receiving the determination result of corrosion occurrence “presence” determined in S103, the determination result of corrosion progress “presence” determined in S104, and the corrosion progress rate set in S105. judge. As described above, in the second embodiment, the corrosion risk is determined based on the corrosion state of the pipe 101.

As described above, in the second embodiment, the corrosion resistance of the material can be directly monitored, the influence of the environmental factor on the pipe 101 can be quantitatively determined from the material potential, and the corrosion risk can be determined with high accuracy.

Next, the measurement result of the material potential with respect to the time described in Example 2 will be described.

FIG. 8 is an explanatory diagram illustrating the measurement result of the material potential with respect to the time described in Example 2.

In FIG. 8, the material potential rises about 200 days after the start of measurement. This indicates that the stable film of the material such as the passivation film was dissolved and the active dissolution was started in response to the environmental change. Further, also in FIG. 5, the electric conductivity reached 50 mS / cm about 200 days after the start of the measurement, and the pH reached 4 about 200 days after the start of the measurement. In this way, the material potential also changes with changes in electrical conductivity and pH.

That is, the material potential is monitored together with the electrical conductivity and pH to identify the time of occurrence of local corrosion.

In this way, in Example 2, the material potential is monitored together with the electrical conductivity and pH, the corrosion incubation period and the corrosion progress period are separated, the corrosion occurrence time of local corrosion is specified, and the corrosion risk is determined. The remaining life of the pipe 101 can be predicted with high accuracy.

Next, the corrosion management system 300 described in Example 3 will be schematically described.

FIG. 9 is an explanatory diagram schematically explaining the corrosion management system 300 described in the third embodiment.

In the corrosion management system 300 described in the third embodiment, the sensor is installed inside the same seat 107 of the pipe 101 in the first embodiment as compared with the corrosion management system 100 described in the first embodiment. The difference is that the sensor is installed on the outside (outer surface side) of the pipe 101. That is, in the third embodiment, the corrosion state on the outer surface side of the pipe 101 due to the external environment such as buried soil is determined.

In the third embodiment, the external environment is the corrosion environment 102, and the corrosion management system 300 has a resistance component monitoring sensor 103 and a target corrosion rate monitoring sensor 111. In the second embodiment, the resistance component monitoring sensor 103 is a sensor that measures the water content of the buried soil, and the target corrosion rate monitoring sensor 111 is a sensor that measures the corrosion current.

Next, the procedure for determining the corrosion risk described in Example 3 will be described.

FIG. 10 is a flow chart illustrating the procedure for determining the corrosion risk described in Example 3.

In the third embodiment, the resistance component monitoring sensor 103 monitors the water content, and the target corrosion rate monitoring sensor 111 monitors the corrosion current.

Hereinafter, the procedure for determining the corrosion risk described in Example 3 will be described based on the difference from Example 1.

(1) The resistance component monitoring sensor 103 measures the water content (S108).

(2) The target corrosion rate monitoring sensor 111 measures the corrosion current (S109).

(3) Similar to the first embodiment, the corrosion risk determination device 106 measures the resistance component monitoring sensor 103 and the target corrosion rate monitoring sensor 111, and uses the data recorded in the data recording device 105 to determine the corrosion risk. Judgment (S106).

The corrosion environment 102 in contact with the pipe 101 and the corrosion environment 102 in contact with the target corrosion rate monitoring sensor 111 may not be equivalent. Therefore, in this case, when setting the corrosion progress rate, for example, the environmental factor between the pipe 101 and the target corrosion rate monitoring sensor 111 is predicted to change linearly, and the data of the resistance component monitoring sensor 103 is corrected. And set the corrosion progress rate.

Next, the measurement results of the corrosion current and the water content with respect to the time described in Example 3 will be described.

FIG. 11 is an explanatory diagram illustrating the measurement results of the corrosion current and the water content with respect to the time described in Example 3.

In FIG. 11, the corrosion current increases at the moment when the water content increases (for example, after about 25 hours or about 50 hours). Corrosion current decreases gently. That is, the momentary change (increase) in the corrosion current and the water content can be regarded as the occurrence of corrosion. Then, the subsequent corrosion current can be regarded as the corrosion progress rate.

The corrosion current and water content are measured at 1-minute intervals. In particular, the corrosion current and water content are preferably measured at short intervals.

In this way, in Example 3, the corrosion current and the water content are monitored, the corrosion incubation period and the corrosion progress period are separated, the corrosion occurrence time of local corrosion is specified, the corrosion risk is determined, and the remainder of the pipe 101 is determined. The life can be predicted with high accuracy.

Next, the corrosion management system 400 described in Example 4 will be schematically described.

FIG. 12 is an explanatory diagram schematically explaining the corrosion management system 400 described in the fourth embodiment.

The corrosion control system 400 described in Example 4 acquires experimental data in advance in a laboratory, classifies the corrosion latency period and the corrosion progress period based on the experimental data, and determines the corrosion occurrence time of local corrosion. It identifies, determines the risk of corrosion, and predicts the remaining life of the pipe 101 with high accuracy.

The corrosion management system 400 includes a measuring container 121, a target corrosion rate monitoring sensor 111, a test piece 112 made of the same material as the pipe 101, a data recording device 105, and a corrosion risk determination device 106. Then, in the measuring container 121, for example, seawater that simulates the corrosive environment 102 is stored. Further, although not shown, for example, a resistance component monitoring sensor 103 and a driving force component monitoring sensor 104 are installed.

The corrosion management system 400 is a system for clarifying environmental factors affecting the corrosion environment 102 so that the remaining life of the pipe 101 can be predicted with high accuracy and in a single manner.

Next, the procedure for determining the corrosion risk described in Example 4 will be described.

FIG. 13 is a flow chart illustrating the procedure for determining the corrosion risk described in Example 4.

(1) In Example 4, the electrical resistance and pH are set (S101 and S102). That is, one type of seawater in which the corrosive environment 102 is simulated is stored in the measuring container 121.

(2) The material potential and the corrosion current with respect to the time at this time are measured (S110). That is, as one experimental condition, one combination of electrical conductivity and pH is used, the change in the material potential and / and the corrosion current at that time is measured, and this change is recorded. In Example 4, in particular, the change in corrosion current is measured as experimental data.

(3) For example, based on the measured corrosion current, the time when the corrosion of local corrosion occurs in one combination of electrical conductivity and pH is specified, and the corrosion progresses based on the change in the measured corrosion current. Calculate the speed.

(4) Then, different electric resistances and pHs are set, that is, different types of seawater are stored in the measuring container 121, and the material potential and / and the corrosion current with respect to the time at that time are measured, and the electric conductivity and the corrosion current are measured. The time of occurrence of corrosion of local corrosion in the combination of pH is specified, and the corrosion progress rate is calculated based on the change in the measured corrosion current.

(5) By repeating (4), the relationship between the corrosion occurrence time of local corrosion and the corrosion progress rate is accumulated.

For other environmental factors, the same measurement, identification, and calculation are repeated to accumulate the relationship between the corrosion occurrence time of local corrosion and the corrosion progress rate.

Then, when determining the corrosion risk, the relationship between the actually measured electrical resistance and pH and the corrosion occurrence time and corrosion progress rate of local corrosion in the same or similar combination of experimental data is used. As a result, the risk of corrosion can be determined and the remaining life of the pipe 101 can be predicted with high accuracy.

Next, the measurement result of the current density with respect to the time described in Example 4 will be described.

FIG. 14 is an explanatory diagram for explaining the measurement result of the current density with respect to the time described in the fourth embodiment, in which the horizontal axis represents the time and the vertical axis represents the current density converted from the corrosion current.

As shown in FIG. 14, the time when the current density increases can be specified as the time when corrosion occurs, and when the current density does not decrease after increasing, it can be determined as corrosion progress. Then, based on the current density, the corrosion progress rate can be calculated by using Faraday's law or the like.

As described above, in Example 4, the corrosion risk is determined by using the experimental data, specifying the corrosion occurrence time of local corrosion in advance for a specific environmental factor, and calculating the corrosion progress rate, and the piping 101. The remaining life of the product can be predicted with high accuracy.

The present invention is not limited to the above-described examples, and includes various modifications. For example, the above-described embodiment has been specifically described in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations.

It is also possible to replace a part of the configuration of one embodiment with a part of the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete a part of the configuration of each embodiment, add a part of the other configuration, and replace it with a part of the other configuration.

100, 200, 300, 400 ... Corrosion management system,
101 ... Monitoring object (piping),
102 ... Corrosive environment,
103 ... Resistance component monitoring sensor,
104 ... Driving force component monitoring sensor,
105 ... Data recording device,
106 ... Corrosion risk determination device,
107 ... Seat 111 ... Target corrosion rate monitoring sensor,
112 ... Test piece 121 ... Measuring container.

Claims (8)

A resistance component monitoring sensor that monitors the electrical resistance component of a corrosive environment,
A driving force component monitoring sensor that monitors the driving force component that promotes corrosion in the corroded environment, and a driving force component monitoring sensor.
A data recording device that records data output by the resistance component monitoring sensor and the driving force component monitoring sensor, and
Using the data of the data recording device, the corrosion risk determination device that identifies the corrosion occurrence time of local corrosion, sets the corrosion progress rate, and determines the corrosion risk,
Corrosion management system characterized by having. The corrosion management system according to claim 1.
A corrosion management system, wherein the resistance component monitoring sensor is a sensor that measures electrical conductivity, and the driving force component monitoring sensor is a sensor that measures pH. The corrosion management system according to claim 1.
A corrosion management system characterized in that the resistance component monitoring sensor and the driving force component monitoring sensor are installed at a plurality of locations in a pipe and are installed inside the same seat of the pipe. The corrosion management system according to claim 2.
A corrosion management system characterized in that the presence or absence of corrosion occurrence and the presence or absence of corrosion progress are determined based on the electrical conductivity and the pH. The corrosion management system according to claim 3.
A corrosion management system characterized in that the type of fluid flowing through the pipe is seawater. The corrosion management system according to claim 3.
A corrosion management system characterized in that a target corrosion rate monitoring sensor for monitoring the corrosion resistance of a material is further installed inside the same seat of the pipe. The corrosion management system according to claim 1.
A corrosion management system characterized in that the time when local corrosion occurs is specified in advance by acquiring experimental data in a laboratory and based on the experimental data. The corrosion management system according to claim 3.
The corrosion risk determination device is a corrosion management system characterized in that after maintenance of the piping is performed, the corrosion occurrence time of local corrosion is specified again, the corrosion progress rate is set, and the corrosion risk is determined.

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