JPH06265511A - Method for measuring anticorrosion potential - Google Patents

Abstract

PURPOSE:To obtain a method whereby the anticorrosion potential can be correctly measured for an object to be electrically processed through an anticorrosion treatment. CONSTITUTION:An insulating cylindrical member such as a polyethylene pipe 6 or the like having wet soil sealed therein is set in the ground. The interior of the pipe is held to be an electrolyte (ion conductive). An end part 61 of the pipe in the ground is electrically connected to the soil in the vicinity of a to-be-processed object 1 and the other end part 60 closer to the surface of the ground is opened at the surface 7 of the ground. Moreover, the middle circumferential part of the pipe is electrically insulated from the soil there. The potential between the object 1 which is to be processed through the anticorrosion treatment and the end part 60 of the insulating cylindrical member is measured as the anticorrosion potential.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to measure an accurate potential (hereinafter referred to as a true potential) that does not include an error due to soil resistance in measuring a corrosion potential for an anticorrosion target such as a buried pipe subjected to cathodic protection. Regarding how to do it.

[0002]

2. Description of the Related Art Conventionally, important buried pipes have been subjected to cathodic protection, which has been very effective in maintaining the conduits. Corrosion control at that time is performed by measuring the potential of the pipe (measurement of the potential difference between the pipe buried in the ground and the reference electrode arranged on the ground side). However, since the IR loss caused by soil resistance and anticorrosion current is included in the potential measurement value (referred to as ON potential), the tube potential is measured lower than the actual value (the anticorrosion state seems to be good). Therefore, the unsafe side may be evaluated (Fig. 2).

On the other hand, a small iron piece is buried near the buried pipe as a coating defect portion (pseudo member, FIG. 3), and in a normal state, it is short-circuited with the buried pipe to keep the same potential as the buried pipe to prevent corrosion. There is a method in which the state is made common and this pseudo member is used as one side of potential measurement during measurement. That is,
When measuring the potential, cut off the short circuit between the buried pipe and the pseudo member,
The potential of the pseudo member at that moment (ms order) is defined as the "true potential" of the tube. In the case of this method, it is necessary to install the reference electrode near the pseudo member. Because, when the above short circuit is cut, the anticorrosion current to the pseudo member becomes zero and the IR loss around the pseudo member disappears, but the anticorrosion current to the buried pipe is maintained as it is, and the IR around the buried pipe is maintained. The loss is not gone.

[0004]

Therefore, in the prior art, when the former method is adopted to measure the potential between the buried pipe and the ground surface, the IR loss between the ground surface and the buried pipe is eliminated. It is necessary to take measures (for example, temporarily cut the anticorrosion current and measure the potential immediately after the disconnection). On the other hand, in the latter case, the verification electrode is buried not near the ground surface but near the pseudo member, and the potential of the pseudo member is measured. At that time, the long-term reliability of the verification electrode in the ground becomes a problem. . Current,
No reference electrode with long-term reliability under such an environment is commercially available.

Therefore, an object of the present invention is to obtain a method for measuring anticorrosion potential which can accurately measure the anticorrosion potential of an anticorrosion target buried in the ground.

[0006]

[Means for Solving the Problems] The characteristic means of the method for measuring anticorrosion potential according to the first invention of the present application for achieving this object is that the inside is an electrolyte (ion conductivity), and the anticorrosion at the end on the ground side is performed. An electrically insulating tubular member electrically connected to the soil in the vicinity of the object, having its end on the surface side open to the ground surface, and electrically insulated from the surrounding soil at the intermediate peripheral portion is disposed in the soil. That is, the potential between the anticorrosion target and the ground-side end of the insulating tubular member is measured to obtain the anticorrosion potential. Further, the characteristic means of the anticorrosion potential measuring method according to the second invention of the present application, is composed of the same material as the anticorrosion target, and is embedded in the soil in the vicinity of the anticorrosion target a pseudo member that can short-circuit with the anticorrosion target,
The inside is an electrolyte (ion conductivity), the ground side end is electrically connected to the soil in the vicinity of the pseudo member, the ground side end is open to the ground surface, and the peripheral soil at the intermediate peripheral part An insulating tubular member electrically insulated from the
In the normal anticorrosion state, the anticorrosion target and the pseudo member are kept in a short-circuit state, and when measuring the anticorrosion potential, the short-circuit state between the anticorrosion target and the pseudo member is cut off. The purpose is to measure the potential between the part and the pseudo member to obtain the anticorrosion potential, and the action and effect are as follows.

[0007]

In other words, in the constructions of both inventions, in the former case, the insulating tubular member is arranged between the ground surface and the soil near the anticorrosion object and in the latter case between the ground surface and the soil near the pseudo member. The inside of this member is kept ionic conductive and at the same potential. Therefore, by providing this member, when the reference electrode is connected to the ground-side end in the measurement of the anticorrosion potential, this electrode extends to the ground-side end. Therefore, in the configuration of the first invention, the true anticorrosion potential can be accurately measured without including the IR loss between the anticorrosion target and the ground surface in the potential measurement value. On the other hand, in the configuration of the second invention, at the time of measuring the anticorrosion potential, even if the short-circuit state between the pseudo member and the anticorrosion object is cut off, the IR loss due to the anticorrosion current flowing to the buried pipe side is measured. The problem of being included in the value is eliminated, and the true true anticorrosion potential can be measured as well.

[0008]

As a result, it becomes possible to accurately evaluate the "true potential" of the anticorrosion target, for example, it is possible to eliminate the excess or deficiency of the electrocorrosion protection of the buried pipe and to contribute to ensuring the safety. . Furthermore, if the insulating tubular member is a polyethylene pipe, and the soil is placed inside the polyethylene pipe, and water is allowed to penetrate into the polyethylene pipe, the inside of the polyethylene pipe is kept ionic conductive. It is possible to secure the bridge structure,
The anticorrosion potential can be stably and accurately measured semipermanently, and for example, it is possible to contribute to ensuring the long-term reliability of the buried pipe.

[0009]

Embodiments of the present application will be described with reference to the drawings. FIG. 1 shows a situation of a buried pipe 1 as an anticorrosion object to which the method of the present application is applied.

First, the cathodic protection structure will be described. For the buried pipe 1 to be protected against corrosion, the counter electrode 3 is installed in the soil 2 in which the buried pipe 1 is buried, and the buried pipe 1,
An external DC power supply 4 is provided across the counter electrode 3 such that the negative electrode side is connected to the buried pipe 1 and the positive electrode side is connected to the counter electrode 3. With this configuration, the anticorrosion current flows from the counter electrode 3 to the buried pipe 1 through the soil 2.

Next, a structure for measuring the anticorrosion potential using the iron piece 5 as a pseudo member for measuring the anticorrosion potential will be described. This mechanism is provided in the protector section A. As shown in the figure, an iron piece 5 composed of the same material as the buried pipe 1 and short-circuitable with respect to the buried pipe 1 is buried in the soil in the vicinity of the buried pipe 1, and this is connected to a voltmeter 9 for measuring the anticorrosion potential. It On the other hand, with respect to the iron piece 5, a polyethylene pipe 6 as an insulating tubular member is arranged so as to extend from the ground surface 7 to a portion in the vicinity of the iron piece 5. Soil is inserted into the polyethylene pipe 6, and when the polyethylene pipe 6 is placed in the soil, water is allowed to penetrate into the polyethylene pipe 6, whereby the inside of the pipe can be kept in a moisturized state. . In this state, the inside of the polyethylene tube 6 is kept ionic conductive. Further, the inside of the polyethylene pipe 6 and the soil 2 in the peripheral portion are kept in an insulating state. When measuring the anticorrosion potential, iron pieces 5 and polyethylene pipes 6 buried in the soil
The electric potential is measured with the soil at the end portion 60 on the ground surface side as shown in the figure.

The measurement of the anticorrosion potential will be described below.
In measuring the anticorrosion potential, a DC voltmeter 9 is arranged between the iron piece 5 and the verification electrode 8 electrically connected to the soil in the ground-side end portion 60 of the insulating tubular member. Measure the potential difference. When measuring the electric potential, the short-circuit state between the iron piece 5 and the buried pipe 1 is cut off. When such a measuring method is adopted, on the side of the reference electrode 8, the same effect as that of filling the reference electrode up to the underground end 61 of the polyethylene pipe 6 is obtained (current flows in the polyethylene pipe 6). Because there is no, there is an equipotential from the top to the bottom of the soil in the pipe). Further, the influence of the anticorrosion current on the buried pipe 1 can be minimized. Therefore, the true anticorrosion potential can be measured more accurately than before. Further, since the polyethylene tube 6 does not have a problem of corrosion or the like, it is possible to accurately perform the measurement with a much longer life as compared with the case where the reference electrode 8 is extended to the vicinity of the iron piece 5 and grounded.

[Other Embodiments] In the above embodiment, a pseudo member such as an iron piece 5 is provided for the buried pipe 1, and this is used for measuring the corrosion protection potential, but insulation is performed directly in the vicinity of the buried pipe 1. The flexible tubular member may be provided upright. In this case, the potential difference is measured between the buried pipe 1 and the reference electrode electrically connected to the soil at the end on the ground side of the tubular member, and the true potential is similarly easily measured. Further, as the object of cathodic protection, in addition to the above-mentioned buried pipe 1, underground constructions and the like are also objects of the present application.

It should be noted that although reference numerals are given in the claims for convenience of comparison with the drawings, the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing a state of measuring anticorrosion potential using the soil-embedded salt bridge of the present application.

FIG. 2 is a diagram showing a conventional anticorrosion potential measurement state.

FIG. 3 is a diagram showing a state of measuring an anticorrosion potential using a pseudo member.

[Explanation of symbols]

 1 Corrosion protection object 2 Soil 3 Counter electrode 4 External power supply 5 Pseudo member 6 Polyethylene pipe 7 Ground surface 60 Ground surface side edge 61 Ground side edge

Claims (3)

[Claims] 1. A negative electrode is connected to an anticorrosion object (1) to be anticorrosion, and a positive electrode side is connected to a counter electrode (3) provided in a soil (2) in which the anticorrosion object (1) is arranged. A method for measuring the anticorrosion potential of an anticorrosion target (1) which is galvanically protected by providing an external power source (4) connected to the soil (2) side and supplying an anticorrosion current from the soil (2) side to the anticorrosion target (1) side. And the inside is an electrolyte and is electrically connected to the soil in the vicinity of the anticorrosion target (1) at the ground-side end (61), and the ground-side end (60) is open to the ground surface (7). And an insulating cylindrical member electrically insulated from the peripheral soil (2) at the intermediate peripheral portion is disposed in the soil, and the corrosion protection target (1) and the ground of the insulating cylindrical member are disposed. A method for measuring anticorrosion potential in which the potential with the front end (60) is measured to obtain the anticorrosion potential. 2. The negative electrode side is connected to the anticorrosion object (1) to be anticorrosion, and the positive electrode side is connected to the counter electrode (3) provided in the soil (2) in which the anticorrosion object (1) is arranged. A method for measuring the anticorrosion potential of an anticorrosion target (1) which is galvanically protected by providing an external power source (4) connected to the soil (2) side and supplying an anticorrosion current from the soil (2) side to the anticorrosion target (1) side. A pseudo member (5) made of the same material as the anticorrosion target (1) and short-circuitable with the anticorrosion target (1) is embedded in the soil (2) near the anticorrosion target, The inside is an electrolyte, and the ground side end (61) is the pseudo member (5).
Insulating tubular member electrically connected to the soil in the vicinity of the ground, the ground side end (60) is opened to the ground surface (7), and is electrically insulated from the peripheral soil (2) at the intermediate peripheral portion. Is placed in the soil (2), and the anticorrosion object (1) and the pseudo member (5) are kept in a short-circuited state in a normal anticorrosion state, and the anticorrosion object ( The short-circuited state between 1) and the pseudo member (5) is cut off, and immediately after that,
An anticorrosion potential measuring method for measuring an electric potential between the ground-side end (60) of the insulating tubular member and the pseudo member (5) to obtain an anticorrosion potential. 3. The insulating cylinder member is configured to have a polyethylene pipe (6) installed in the soil (2),
The soil is arranged inside the polyethylene pipe (6), and the inside of the polyethylene pipe (6) is made into an electrolyte by permeating water into the polyethylene pipe (6). The method for measuring anticorrosion potential described.