JPH0821815A - Corroded state detecting method and device for water feed/drainage device and water feed/drainage device equipped with this detecting device - Google Patents

Abstract

PURPOSE:To correctly measure the corroding speed with a simple action and a device by feeding a reference solution to a measurement region in a pipe, electrically exciting a pipe wall, obtaining the potential of the pipe wall against a reference, feeding a corrosion accelerating solution, obtaining the potential of the pipe wall, and comparing two potentials to obtain the corroding speed. CONSTITUTION:A potentiometer 37 having a reference electrode 32 and a measuring electrode 33 is arranged at the measurement region 36 of a passage 21, and a passage 27 feeding a corrosion accelerating liquid, a discharge passage 31, and a by-pass passage 23 are provided. Valves 24, 25 are opened, valves 28, 30, 34, 35 are closed, water (reference solution) is fed to the passage 21, a voltage is applied to the measurement region 36, and the potential of the pipe wall 33 against the reference electrode 32 is measured by the potentiometer 37. The valves 24, 25 are closed, the valves 34, 35 are closed, water feed is continued via the by-pass passage 23, the valves 28, 30 are opened to guide a sodium chloride solution to the measurement region 36 from the passage 27, and it is discharged from the discharge passage 31 after the similar potential measurement. Corroding speed is obtained from the difference between two detected potentials via a diagram prepared in advance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a corrosion state of a water supply / drainage device such as a piping device, a water supply tank, a drainage tank, and the like.
The present invention relates to a method for detecting a corrosion state of a piping device. The present invention also relates to a piping device including a corrosion state detecting device, a water supply / drainage device such as a water supply tank and a drainage tank, and particularly to a piping device including a corrosion state detecting device.

[0002]

2. Description of the Related Art Corrosion measurement of water supply / drainage equipment such as water pipes in buildings, ships and other structures that is generally performed is performed by measuring the corrosion potential and polarization curve using an electrochemical method and by the polarization resistance method. Is done by. However, in the field measurement for the structure of the water supply / drainage device, since it can be measured by measuring the potential difference between the reference electrode and the measurement electrode, the device is less expensive than the measurement of the polarization curve and the polarization resistance method. In addition, the corrosion potential is mainly measured because it is easy to operate and does not disturb the corrosion system in the pipe.

[0003]

However, since the corrosion potential measurement is to obtain the spontaneous potential of corrosion, only equilibrium information can be obtained, so that the corrosion rate cannot be accurately measured, which is a problem. Was said. An object of the present invention is to solve the problem related to the measured value of corrosion potential measurement.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a corrosion rate measuring method and device which can be measured by a simple operation of measuring corrosion potential and an inexpensive device. That is, the present invention is to hold a sample piece in an electrochemical measurement container and introduce a reference solution, connect the sample piece to a power source, measure the potential of the sample piece with respect to a reference electrode, and then measure the measurement container. Introduce a corrosion accelerating solution into the sample, determine the potential of the sample piece with respect to the reference electrode, and compare the measured potentials to determine the corrosion rate of the sample piece. Also, the present invention, in the method for detecting a corrosion state of a pipeline, injecting a reference solution into a measurement region in the pipeline, electrically urging the wall of the pipeline in the measurement region, to the reference electrode. The potential of the pipeline wall of the measurement region is measured, and then the corrosion promoting solution is flown into the pipeline of the measurement region to measure the potential of the pipeline wall of the measurement region with respect to the reference electrode, and these measurements are made. Pipe wall for a fixed reference electrode In corrosion state detecting method of a pipe passage and obtains the corrosion rate of the pipe passage by comparing the potential.

Further, according to the present invention, a pipe water channel and a bypass flow passage connecting a first branch point formed on the upstream side of the pipe water channel and a second branch point formed on the downstream side of the pipe water channel. An on-off valve provided on the upstream side and a downstream side between the first branch point and the second branch point of the pipe water channel, and a corrosion-promoting solution inlet port and a corrosion-promoting port formed between these on-off valves. A solution discharge port, a corrosion-accelerating solution tank connected to the corrosion-accelerating solution introducing port via an on-off valve, and a standard that is liquid-tightly inserted in a pipe water channel between the corrosion-accelerating solution introducing port and the discharge port. An electrode and a pipe wall of the measurement electrode,
The reference electrode and the measuring electrode are connected to a potentiometer, which is a piping device equipped with a corrosion state detecting device.

In the present invention, the object whose corrosion state is detected is a metal sample used in a corrosive environment or a pipe wall of a pipe line. The metal sample is hung as a test piece side in the measurement cell as a sample piece, and is connected to the test electrode side of the potentiometer, and the corrosion potential with respect to the reference electrode connected to the reference electrode side of the potentiometer is measured. . In the present invention, the reference electrode is an electrode serving as a reference for electrochemically measuring the electrode potential, and includes a standard hydrogen electrode, a saturated calomel electrode, and a silver / silver chloride electrode.

In the case of the pipe wall of the pipe passage, the test electrode side of the potentiometer is attached to a part of the pipe wall exposed in the measurement region formed between the upstream side opening / closing valve and the downstream side opening / closing valve in the branch pipe. By connecting and forming a through hole in a part of the tube wall of the measurement area of the branch pipe, the reference electrode connected to the reference electrode side of the potentiometer is liquid-tightly inserted and held in the through hole, Then, the corrosion potential of the tube wall, which is the test electrode with respect to the reference electrode, is measured. The measurement of the corrosion potential is performed in the reference solution or the corrosion promoting solution, and the difference in the corrosion potential measured in the reference solution or the corrosion promoting solution, that is, the potential response width is obtained.

In the present invention, the standard solution means water used for tap water and other feed water, as well as factory drainage such as low-concentration washing water and cooling water system such as air conditioning. In the present invention, the corrosion accelerating solution is for changing the solution environment existing around the metal in order to obtain a potential response indicating the corrosion state of the metal, and as the corrosion accelerating solution, chloride ions are generated, For example, a solution of ionic bond chloride having a substantially neutral pH is used, and typically, as the chloride ion solution, an alkali metal chloride solution such as sodium chloride or potassium chloride is used. As the corrosion promoting solution, a dilute solution of these chloride solutions is used. The concentration of sodium chloride ions in the sodium chloride solution is 1 mol or less, and a chloride solution diluted to a chloride ion concentration of 0.2 mol or less can be used. However, a chloride ion concentration of 0.1 to 0.01 mol is preferable because the corrosion rate can be measured without disturbing the corrosion system of the measurement sample and the pipe wall to be measured.

In the present invention, it is preferable that an on-off valve is provided in the front and rear of the pipe line to form a measurement region. In the measurement area, a reference electrode is provided so as to protrude inside the pipeline.
However, in this way, if a measurement region is formed in a part of the pipeline, at the time of detecting the corrosion state, water supply and drainage by the pipeline will be stopped, so even when detecting such a corrosion state, When water supply and drainage of the pipeline are continued, the pipeline is branched by, for example, a three-way branch pipe to form a measurement region equipped with a reference electrode in one of the branched pipelines, and the pipe wall of the pipeline is corroded. It is preferable that the remaining pipeline is subjected to a state detection test, and the remaining one pipeline is formed as a detour used for water supply and drainage of the pipeline when a corrosion state is detected.

When measuring regions are formed in both of the branched pipes formed in the pipeline, the corrosion potential when the corrosion promoting solution is flown and the corrosion potential when water is flown are measured in each pipeline. The measurement can be performed simultaneously, and the average value of the difference (potential response width) or ratio of both potentials measured immediately can be obtained. When forming a measurement region in each of the plurality of branched pipelines formed in this pipeline, the plurality of branched pipelines are provided so that water supply and drainage can be continued when a corrosion state is detected. Separately, it is necessary to branch the detour from the pipeline.

In the present invention, when there is no difference in the value of the corrosion potential measured in the reference solution such as water and in the corrosion accelerating solution, it means that the corrosion state has not progressed, and the difference appears. Time indicates that the corrosion state is progressing and the corrosion rate is high depending on the size of the difference. In the present invention, the corrosion rate is obtained by the difference between the corrosion potentials in the measured reference solution such as water and the corrosion acceleration solution, that is, the potential response width, but the corrosion rate can be obtained by the ratio of both corrosion potentials. it can. In any case, the corrosion rate corresponding to the magnitude of the difference between the two corrosion potentials or the ratio of the two corrosion potentials is obtained in advance and is prepared in, for example, a table or a diagram, and the table and the diagram correspond to each other. Corrosion rates corresponding to differences or ratios of corrosion potentials can be determined.

In the present invention, the corrosion rate corresponding to the measured difference in corrosion potential can be measured by a polarization resistance method, a rectangular wave polarization resistance method, or the like. However, in order to obtain the corrosion rate without disturbing the corrosion system in the measurement area of the measurement cell and the pipe, it is preferable to use the rectangular wave polarization resistance method. In the present invention, the corrosion potential measurement for detecting the corrosion state is performed in a measuring cell while disturbing a reference solution such as water or a corrosion accelerating solution with a stirrer such as a stirrer, and in the measurement area in the pipeline, It is performed while flowing a reference solution such as water or a corrosion promoting solution into the measurement area.

[0013]

According to the present invention, the corrosion potential of a metal sample or a pipe wall of a pipeline for detecting a corrosion state is measured in a reference solution such as water and a corrosion accelerating solution and measured in a reference solution such as water. The difference between the corrosion potential and the corrosion potential measured in the corrosion promoting solution, that is, the potential response width, or the ratio of the corrosion potential measured in the reference solution such as water and the corrosion potential measured in the corrosion promoting solution, From the empirical formula, table or diagram showing the relationship of the corrosion rate corresponding to the difference or ratio of the corrosion potentials created in advance, calculate the corrosion rate corresponding to the value of the difference or ratio of the two corrosion potentials, metal sample and pipe Since the corrosion state of the road is detected, the corrosion rate can be obtained only by measuring the corrosion potential that can be performed by a simple operation.

As described above, according to the present invention, the measurement of the corrosion rate by the polarization resistance method or the rectangular wave polarization resistance method is performed by using an empirical formula, a table or a line indicating the relationship of the corrosion rates corresponding to the difference or the ratio of the corrosion potentials. Since it is sufficient to perform it at the stage of creating a diagram, for example, the corrosion state of the pipe wall of the pipeline can be easily and easily known by measuring the corrosion potential in the reference solution such as water and the corrosion promoting solution. You can

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited by the following description and examples. FIG.
FIG. 3 is an explanatory diagram showing an outline of a measuring cell used in one embodiment of the present invention, FIG. 2 is a system diagram of another embodiment of the present invention, and FIG. 3 is a diagram of the embodiment shown in FIG. FIG. 3 is a schematic enlarged partial cross-sectional view mainly showing a reference electrode mounting structure in a measurement region. FIG. 4 shows the difference in corrosion potential, that is, the potential response width (ΔE _corr ), and the corrosion rate (log) when chloride ions such as sodium chloride ions were added to have a molar concentration of 1.
is a diagram showing the relationship between l _corr), FIG. 5, when the chloride ions such as sodium chloride ions are added to a 0.1 molar concentration, the difference in corrosion potential i.e. potential response width (Delta] E _corr) And FIG. 6 is a diagram showing the relationship between the corrosion rate and the corrosion rate (logl _corr ), and FIG. 6 shows the case where chloride ions such as sodium chloride are added so as to have a 0.1 molar concentration.
It is a diagram showing the relationship of the difference between the corrosion potential i.e. potential response width (Delta] E _corr) and corrosion rate _{(logl co rr).} Figure 7
FIG. 4 is a diagram showing changes in potential response (E _corr ) and corrosion rate (l _corr ) with respect to changes in chloride ion concentration (molar) such as sodium chloride in tap water.

In FIG. 1, the measuring tank 1 has a wide-mouthed container 3 having a stopper 2. The stopper 2 has a funnel 4 for supplying a 0.1 mol sodium chloride solution, a pipe 5 for introducing air,
A salt bridge 6, a counter electrode 8 including a platinum plate 7, and a test electrode 10 holding a sample piece 9 to be measured are fixed. Measuring tank 1
A stirrer 12 is rotatably arranged on the bottom 11 of the
The rotor 12 is a stirrer 1 provided below the container 3.
It is rotationally driven by 3. In this example, a reference electrode 14 that movably communicates with the measurement tank 1 via a salt bridge 6 is provided. The reference electrode 14 is formed by immersing the tip of a silver / silver chloride electrode member 16 in a saturated solution 15 of potassium chloride.

In this example, the test electrode 10 was replaced with a potentiometer 1.
A circuit 18 connected to the reference electrode 14 via 7 is formed. This circuit is connected to the power supply 2 via the resistanceless ammeter 19.
It is connected to the negative electrode of 0. In the measuring tank 1 of this example, the counter electrode 8 is connected to the positive electrode of the power source 20 so that the corrosion rate can be measured by the rectangular wave polarization resistance method.

Since this example is constructed as described above,
Water is put in the container 3, the stopper 2 is fitted, the stirring bar 12 is rotated, and the corrosion potential of the sample piece 9 is measured by the potentiometer 17. When this corrosion potential is measured, the corrosion rate is obtained by the rectangular wave polarization resistance method. That is, in this example, a polarization conductance measuring device (not shown) is used, and a function generator (not shown) is used.
From the galvanostat (not shown) driven by, a rectangular wave current is passed through the measuring tank 1 to obtain the solution resistance (Rs) and the total resistance (Rt), and the polarization resistance (R
p) is calculated from the formula: Rp = Rt−Rs to obtain the corrosion rate. Next, the stopper 2 was removed, the water in the container 3 was drained, and when the inside of the container 3 was emptied, the stopper 2 was inserted and the funnel 4 was closed.
A 1 molar sodium chloride solution is supplied into the container 3 and the corrosion potential of the sample piece 9 is measured by a potentiometer 17.

The difference between the corrosion potential measured with water and the corrosion potential measured with a 0.1 molar NaCl solution, that is, the potential response width is ΔE (mV), and the real-time corrosion rate is C As (mA / cm ² ), the following empirical formula: ΔE = 4.4 × 10 log C + 1.6 was obtained.

When tap water, a 5 × 10 ⁻⁴ mol solution of potassium sulfate or a 0.01 mol solution of potassium sulfate was used as a reference solution, the corrosion potential measured with these reference solutions and the 1 mol sodium chloride solution were measured. The difference between the corrosion potentials, that is, the relationship between the potential response width and the corrosion rate has a correlation coefficient of 0.97,
The following empirical formula was calculated: ΔE = 1.6 × 10 ² + 1.4 × 10 ² logC. The relationship between the potential response width and the corrosion rate is shown in FIG. In the figure, the circles represent the potential response width in the case of tap water, the black squares represent the potential response width in the case of a potassium sulfate 5 × 10 ⁻⁴ mol solution, and the black triangles represent the potassium sulfate 0.01 mol. The relationship between the potential response width and the corrosion rate in the case of a solution is shown.

Standard solution of tap water or potassium sulfate 5 × 1
The difference between the corrosion potential measured in a ^0-4 molar solution and the corrosion potential measured in a 0.1 molar NaCl solution and the corrosion rate is a correlation coefficient of 0.90 with the following empirical formula: ΔE = 3.3 x 10 + 5.8 x 10 log C was determined. The relationship between the potential response width and the corrosion rate is shown in FIG. In the figure, the circles indicate the potential response width in the case of tap water, and the black squares indicate the relationship between the potential response width and the corrosion rate in the case of a 5 × 10 ⁻⁴ mol solution of potassium sulfate.

Furthermore, the corrosion potential measured with a standard solution of tap water, a 5 × 10 ⁻⁴ mol solution of potassium sulfate or a 0.01 mol solution of potassium sulfate, and the corrosion potential measured with a 0.01 mol NaCl solution. The correlation between the difference and the corrosion rate was 0.90, and the following empirical formula: ΔE = 2.5 × 10 + 3.3 × 10 log C 2 was obtained. The relationship between the potential response width and the corrosion rate is shown in FIG. In the figure, the circles represent the potential response width in the case of tap water, the black squares represent the potential response width in the case of a potassium sulfate 5 × 10 ⁻⁴ mol solution, and the black triangles represent the potassium sulfate 0.01 mol. The relationship between the potential response width and the corrosion rate in the case of a solution is shown.

In this example, when performing corrosion measurement, if chloride ions were removed and returned to the original solution environment, that is, the reference solution, it was determined whether or not the disorder of the corrosion system due to chloride ions remains. FIG. 7 shows the results of examining the state of corrosion by repeating the addition of chloride ions to the standard solution and the replacement of a new standard solution. In FIG. 7, white circles represent the standard solution, and shaded areas represent the chloride ion concentration of 0.1 mol. Square marks indicate the measurement of corrosion rate. The horizontal axis is timed, indicating that there were four chloride ion additions.

As shown in the above empirical formula and FIGS. 4 to 6, the corrosion potential measured with a reference solution such as water in this example and the corrosion potential measured with a NaCl solution having an ion concentration of 0.1 mol. The difference, that is, the potential response width ΔE (mV) is log
It has a linear relationship with C, and the corrosion rate D can be calculated by calculating the corrosion potential. This corrosion rate corresponded well with the real-time corrosion rate. It is shown that the corrosion rate with respect to the potential response width can be measured more accurately as the sodium chloride concentration of the sodium chloride solution is smaller, but when the concentration is 0.01 mol or less, it is almost equivalent to tap water. It becomes the concentration of the product ions, the measured value of the potential response width becomes small, and an error easily occurs.

In the embodiment shown in FIG. 2, the pipe line 21
In addition, a bypass 23 is formed by branching at the branch point 22. A first opening / closing valve 24 is formed on the upstream side of the pipeline 21, and a second opening / closing valve 25 is formed on the downstream side of the pipeline 21. The bypass 23 is located on the downstream side of the second opening / closing valve 25. Connected to. The pipe line 21 is located at a point 2 that follows the first opening / closing valve 24.
A branch is made at 6 to form a 0.1 molar sodium chloride solution supply channel 27. The sodium chloride solution supply flow path 27 has a third opening / closing valve 28, and sends the sodium chloride solution to a pipe line 21 to a 0.1 molar sodium chloride solution tank (not shown). It is connected via a liquid pump (not shown).

The pipe line 21 is branched at a location 29 on the upstream side of the second opening / closing valve to form a sodium chloride solution discharge passage 31 having a fourth opening / closing valve 30. The reference electrode 32 is provided between the branch points 26 and 29 of the pipe line 21.
It is provided so as to project inside. The pipe passage wall 33 around the reference electrode 32 serves as the test electrode 33 and serves as the measurement area 36.
Are formed. The reference electrode 32 and the test electrode 33 are connected to a potentiometer 37. On the other hand, the detour 23 is provided with the fifth opening / closing valve 34 on the upstream side and the sixth opening / closing valve 3 on the downstream side.
5 is provided.

Since this example is constructed as described above,
When water is supplied through the pipeline 21, the first opening / closing valve 24
The second on-off valve 25 is opened, and the second to sixth on-off valves are closed. The measurement of the corrosion potential due to water is performed while water is being supplied through the pipe line 21 in this manner. The value of the corrosion potential due to water is read when the corrosion potential of the potentiometer 37 reaches a steady value. When the measurement is over,
The first and second on-off valves 24 and 25 are closed, and the fifth and sixth
The on-off valves 34 and 35 are opened, water is supplied through the bypass 23, and the corrosion potential of the sodium chloride solution is measured.

To measure the corrosion potential using a sodium chloride solution, open the third and fourth on-off valves 28 and 30, and set to 0.
It is carried out while flowing a 1 molar sodium chloride solution through the measurement region 37 into the discharge path. While flowing the 0.1 molar sodium chloride solution, the value of the corrosion potential of the sodium chloride solution is read when the corrosion potential of the potentiometer 37 reaches a steady value. The difference between the previously read value of the corrosion potential due to water and the value of the corrosion potential due to the sodium chloride solution is obtained, and the corrosion rate is obtained from the empirical formula.

When the measurement of the corrosion potential by this sodium chloride solution is completed, the on-off valve 28 is closed and the first on-off valve 24 is opened to leave the residual sodium chloride in the measurement region at the concentration of 0.1 molar sodium chloride used for the measurement. The solution is discharged from the channel 31. When the sodium chloride solution used for measuring the corrosion potential has been discharged, the second opening / closing valve 25 is opened and the fifth and sixth opening / closing valves 34 and 35 are closed.

When the corrosion rate is detected when the pipe line 21 is used for drainage, the first and second on-off valves 2
4 and 25 are closed, the fifth and sixth on-off valves are opened, and drainage is made to flow to the bypass 23. In this case, the flow path 27
Is connected to the sodium chloride solution tank via the second opening / closing valve 28.

First, the first opening / closing valve 24 and the second opening / closing valve 25.
Is opened and the fifth on-off valve 34 and the sixth on-off valve 35 are closed, the waste water is caused to flow into the measurement region 36, and the value of the corrosion potential of the waste water is read from the steady value of the potentiometer. When the value of the corrosion potential of the waste water is read, the first and second on-off valves 24 and 2 are
5 and the fifth and sixth on-off valves are opened to open the third on-off valve 2
8 is opened, the measurement area is connected to a sodium chloride solution tank, and a 0.1 molar sodium chloride solution is flown into the measurement area 36. While flowing this sodium chloride solution into the measurement region 36, the corrosion potential due to the sodium chloride solution having a concentration of 0.1 mol is read from the steady value of the potentiometer.

FIG. 3 is a partially enlarged cross-sectional view of the measurement area showing the outline of the structure of the mounting portion of the reference electrode in the embodiment shown in FIG. 2, and the portions corresponding to FIG. Has been done. The front and rear pipes 39 and 40 are connected to a part of the measurement region 36 of the pipe passage 21 by a branch pipe joint 38 for mounting the reference electrode 32.

In this example, the branch pipe joint 39 is a branch threaded joint, and a short pipe 42 having a threaded joint end is screwed to the branching portion 41. A stopper 44 made of an elastic member such as rubber is fitted to the non-threaded end portion 43 of the short tube 42, and the reference electrode 3
The plug 2 is held by being inserted through the through hole 45 of the fitted plug 44.

Since this example is constructed as described above,
At the time of measurement, the short pipe 42 having the reference electrode 32 attached thereto is attached to the branching portion 41 of the branch pipe joint by screwing, and when not used, a plug body (not shown) with a screw for sealing is screwed on. . When the mounting structure of the reference electrode 32 of the present example is applied to the pipeline of the embodiment of FIG. 2, the opening / closing valves 34 and 35 are opened, the water supply is passed through the bypass 23, and the opening / closing valves 24 and 25 are closed to close it. Remove the plug for use from the branch part 41,
2 is attached to the branch portion 41. When the short pipe 42 is attached, the opening / closing valves 24 and 25 are opened, water is supplied through the pipe line 21, the opening / closing valves 34 and 35 are closed, and the water supply through the bypass 23 is stopped. The corrosion potential due to water is measured while the water flows through the pipe line 21.

[0035]

INDUSTRIAL APPLICABILITY In the present invention, the corrosion potential of a metal sample or a pipe wall of a pipeline for detecting a corrosion state is measured in water and a corrosion promoting solution, and the corrosion potential measured in water and the corrosion promoting solution are measured. Obtain the difference or ratio of the corrosion potential measured in
From the empirical formula, table or diagram showing the relationship of the corrosion rate corresponding to the difference or ratio of the corrosion potentials created in advance, calculate the corrosion rate corresponding to the value of the difference or ratio of the two corrosion potentials, metal sample and pipe Since the corrosion state of the road is detected, it is possible to obtain the corrosion rate in a short time and with a simple operation as compared with the measurement of the corrosion rate by the conventional polarization resistance method, the rectangular wave polarization resistance method, or the like.

As described above, according to the present invention, since the corrosion rate is obtained by calculating the difference or ratio between the corrosion potential of water and the corrosion potential of the corrosion promoting solution, the corrosion rate by the conventional polarization resistance method or rectangular wave polarization resistance method is obtained. The structure of the measuring device is simpler than that of the above, and the corrosion state of the piping can be controlled at a lower cost compared to the conventional corrosion rate measuring device by installing it at multiple points in the piping. Is superior in terms of quality.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of a measuring cell used in an embodiment of the present invention.

FIG. 2 is a system diagram of a piping line including a measuring cell according to another embodiment of the present invention.

3 is a schematic enlarged partial cross-sectional view mainly showing a reference electrode mounting structure in a measurement region of the embodiment shown in FIG.

FIG. 4 shows the difference in corrosion potential, that is, potential response width (ΔE _corr ), and corrosion rate (logl) when chloride ions such as sodium chloride ions are added so as to have a molar concentration of 1.
It is a figure which shows the relationship of ( _corr ).

FIG. 5 shows that chloride ions such as sodium chloride ion are less than 0.
Difference in corrosion potential, ie, potential response width (ΔE _corr ), and corrosion rate (logl), when added so as to have a molar concentration of 1.
It is a figure which shows the relationship of ( _corr ).

FIG. 6 shows the difference in corrosion potential, that is, the potential response width (ΔE _corr ), and the corrosion rate (logl) when chloride ions such as sodium chloride are added so as to have a concentration of 0.1 mol.
It is a figure which shows the relationship of ( _corr ).

FIG. 7: Potential response (E _corr ) to changes in chloride ion concentration (mol) such as sodium chloride in tap water
It is a figure which shows the change of the corrosion rate (l _corr ).

[Explanation of symbols]

 1 Measuring Tank 2 Stopper 3 Wide Mouth Container 4 Funnel 5 Air Introducing Tube 6 Salt Bridge 7 Platinum Plate 8 Counter Electrode 9 Specimen 10 Test Electrode 11 Bottom of Measuring Tank 12 Stirrer 13 Stirrer 14, 32 Reference Electrode 15 Potassium Chloride Saturated solution 16 Silver / silver chloride electrode member 17,37 Potentiometer 18 Circuit connected to the reference electrode 19 Non-resistance ammeter 20 Power supply 21 Pipeline 22 Branch point 23 Bypass 24 First opening / closing valve 25 Second opening / closing valve 26, 29 Branching point 27 Sodium chloride solution supply flow path 28 Third opening / closing valve 30 Fourth opening / closing valve 31 Sodium chloride solution discharge path 33 Piping path wall 34 Fifth opening / closing valve 35 Sixth opening / closing valve

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[Procedure amendment]

[Submission date] June 1, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

In the present invention, the values of the corrosion potential measured in a standard solution such as water and in a corrosion accelerating solution are different from each other.
When there is not, that is, when the potential response width is small, the potential response width
Has a higher corrosion current than
It shows that the corrosion state is progressing ,
Of the corrosion potential measured in the reference solution and in the corrosion-promoting solution
When the difference appears in the value, that is, when the potential response width is large
Indicates that the corrosion rate is low and the corrosion state has not progressed
Is shown. Opening the value of the corrosion potential measured in this way
The larger the grain size, the lower the corrosion rate.
In the present invention, the corrosion rate is obtained by the difference between the corrosion potentials in the measured reference solution such as water and the corrosion acceleration solution, that is, the potential response width, but the corrosion rate can be obtained by the ratio of both corrosion potentials. it can. In any case, the corrosion rate corresponding to the magnitude of the difference between the two corrosion potentials or the ratio of the two corrosion potentials is obtained in advance and is prepared in, for example, a table or a diagram, and the table and the diagram correspond to each other. Corrosion rates corresponding to differences or ratios of corrosion potentials can be determined.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

As shown in the above empirical formula and FIGS. 4 to 6, the corrosion potential measured with a reference solution such as water in this example and the corrosion potential measured with a NaCl solution having an ion concentration of 0.1 mol. The difference, that is, the potential response width ΔE (mV) is log
It has a linear relationship with C, and the corrosion rate D can be calculated by calculating the corrosion potential. This corrosion rate corresponded well with the real-time corrosion rate. For example,
Referring to FIG. 5, the measurement was performed in a standard solution such as water.
Corrosion Potential Values and Corrosion Measured in Corrosion Accelerating Solutions
The potential difference, that is, the potential response width (ΔE _corr ) is −
Corrosion rate when appearing at 200 mV (log
l _corr ) is on the order of 10 ⁻³ (mA / cm ² ).
In contrast, the potential response width (ΔE _corr ) is 0 mV,
That is, the corrosion measured in a standard solution such as water and in a corrosion promoting solution
Corrosion rate when no difference appears in the value of the erosion potential (logl
_corr ) is of the order of 10 ⁰ (mA / cm ² ).
It Therefore, FIG. 5 shows a case where the potential response width is large.
If the potential response width is small, the corrosion rate is high and
It shows that food is progressing. Moreover, in FIG.
Potential response width m (mV) and corrosion rate logl
_Since the relationship with _corr (mA / cm ² ) is linear,
Figure 5 shows the values of the corrosion potential measured in a standard solution such as water.
There is a gap between the values of the corrosion potential measured in the corrosion-promoting solution.
The larger the value, the smaller the corrosion rate. this
The relationship is the same in FIGS. 4 and 6. Accordingly
4 to 6 show the results in a standard solution such as water and a corrosion-promoting solution.
If there is no difference in the value of the corrosion potential measured in the liquid, immediately
When the potential response width is small, the potential response width is large
Corrosion rate is higher than that of
In addition, in a standard solution such as water and corrosion
When a gap appears in the value of the corrosion potential measured in the developing solution
Corrosion rate is small when the potential response width is large
It means that the corrosion state has not progressed. did
Therefore, as shown in FIG. 4 to FIG.
Development of corrosion potential values measured in liquid and in corrosion-promoting solutions
Corrosion rate increases as the grain size increases, that is, the potential response width increases.
It shows that the degree becomes smaller. It is shown that the corrosion rate with respect to the potential response width can be measured more accurately as the sodium chloride solution of the sodium chloride solution has a lower concentration. It becomes the concentration of the product ions, the measured value of the potential response width becomes small, and an error easily occurs.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

When the corrosion rate is detected when the pipe line 21 is used for drainage, the first and second on-off valves 2
4 and 25 are closed, the fifth and sixth on-off valves are opened, and drainage is made to flow to the bypass 23. In this case, the flow path 27
Is connected to the sodium chloride solution tank via the third opening / closing valve 28.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Daisuke Niimi 3-15-1 Morisaki Yokosuka City, Kanagawa Nissan Morisaki Dormitory 2 Buildings 417

Claims (4)

[Claims] 1. A sample piece is held in an electrochemical measuring container, a reference solution is introduced, and the sample piece is connected to a power source.
The potential of the sample piece with respect to the reference electrode is measured, and then a corrosion promoting solution is introduced into the measurement container to obtain the potential of the sample piece with respect to the reference electrode, and the measured potentials are compared to corrode the sample piece. A method for detecting a corrosion state of a water supply / drainage device, characterized by obtaining a speed. 2. A method for detecting a corrosion state of a pipeline, wherein a reference solution is flown into a measurement area in the pipeline to electrically energize a wall of the pipeline in the measurement area to measure the measurement area relative to a reference electrode. The potential of the pipeline wall is measured, then the corrosion promoting solution is flown into the pipeline of the measurement region, the potential of the pipeline wall of the measurement region with respect to the reference electrode is measured, and these measured standards are measured. A method for detecting a corrosion state of a pipeline, which comprises determining the corrosion rate of the pipeline by comparing the potentials of the walls of the pipeline with respect to the electrodes. 3. A pipe channel, a bypass channel connecting a first branch point formed on the upstream side of the pipe channel and a second branch point formed on the downstream side of the pipe channel, and the pipe channel. Switching valves provided on the upstream side and the downstream side between the first branching point and the second branching point, and a corrosion promoting solution introducing port and a corrosion promoting solution discharging port formed between these opening and closing valves. , A corrosion-promoting solution tank connected to the corrosion-promoting solution inlet through an on-off valve, and a reference electrode liquid-tightly inserted in a pipe water channel between the corrosion-promoting solution inlet and the outlet, and A pipe apparatus having a corrosion state detecting device, comprising: a pipe water channel wall of an electrode, wherein the reference electrode and the measuring electrode are connected to a potentiometer. 4. A bypass passage is provided with an opening / closing valve on the upstream side and the downstream side thereof, respectively, and a corrosion promoting solution introducing port and a corrosion promoting solution discharging port are formed between these opening / closing valves, and the corrosion promoting solution introducing A corrosion accelerating solution tank is connected to the mouth through an on-off valve, and between the corrosion accelerating solution inlet and the outlet,
The pipe apparatus equipped with the corrosion state detecting device according to claim 3, wherein the reference electrode is liquid-tightly inserted into the pipe water passage and the pipe water passage wall of the measurement electrode is provided.