JP3084131B2 - Over-corrosion protection measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to prevent the corrosion of metal laying such as underground pipes (gas, water supply), oil well pipes, oil tanks and the like laid in a corrosive environment. The present invention relates to an over-corrosion prevention measuring apparatus for determining the degree of over-corrosion prevention of the environment around a laid metal body in the anti-corrosion measures to be taken.

[0002]

2. Description of the Related Art An example of a buried pipe buried underground as an example of a laid metal body will be described below. Such buried pipes are provided with cathodic protection to protect them from corrosion. However, too much corrosion protection results in over-corrosion protection, and hydrogen penetrates into the buried pipe from the soil and hydrogen embrittles the material. However, until now, in a real environment, a method of knowing whether or not a buried pipe is affected by hydrogen embrittlement (how much hydrogen is generated around a buried pipe by an anticorrosion current) and how to determine this There were no special measuring devices.

[0003]

Therefore, in an actual buried environment, it is unknown whether or not the buried pipe is affected by hydrogen embrittlement, and the state of hydrogen embrittlement cannot be grasped. Side had to maintain the buried pipes. Therefore, an object of the present application is to provide an over-corrosion protection degree measuring device that determines an over-corrosion protection state in an environment around a laid metal body such as a buried pipe that has been subjected to cathodic protection.

[0004]

In order to achieve this object, a characteristic feature of the apparatus for measuring the degree of anticorrosion according to the present invention is that it can be arranged in an environment and is maintained at a constant potential by a reference electrode. An environment insertion container containing an electrolyte is provided, and a simulated metal part made of the same material as the laid metal body is provided in at least a part of the environment insertion container in an externally exposed state, and an electrolyte is provided inside the simulated metal part. A corrosion-preventing film for preventing corrosion due to contact with the electrode, providing a counter electrode in the electrolytic solution, and configuring the simulated metal portion as a working electrode for the counter electrode. The operation and effect are as follows.

[0005]

The degree of protection against corrosion is used by arranging an environment insertion container in the soil around a buried pipe, for example, a laid metal body. In this arrangement state, the exposed surface of the simulated metal portion comes into contact with soil as an environment due to the arrangement of the simulated metal portion, and is electrically coupled to the electrolyte via the corrosion prevention film on one surface. . At this time, if the environment is in a state of excessive corrosion protection, hydrogen is generated in this portion by electrolysis of water. This atomic hydrogen enters the environment insertion container through the simulated metal part. In this container, a counter electrode is provided, and since the electrolyte is maintained at a constant potential state by the reference electrode, hydrogen atoms invading from the environment become hydrogen ions by a reaction of H → H ⁺ + e ^−. At the same time, it is led to the opposite pole. Thus, the working electrode,
By the ion current flowing between the counter electrodes, the hydrogen concentration in the environment can be confirmed, and the degree of anticorrosion can be determined.

[0006]

Therefore, it is possible to obtain an apparatus for measuring the degree of anticorrosion in an environment around a laid metal body, such as a buried pipe, on which electrolytic protection has been applied. In the place where the metal body to be measured is provided, it is possible to easily obtain and determine information on an appropriate over-corrosion prevention state in the actual environment state.

[0007]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of the tip 1a of the corrosion protection degree measuring apparatus 1, and FIG. 2 shows the state of the environment 3 around the underground pipe 2 as an example of a laid metal body. The state where the determination is performed using the measuring device 1 is shown.

As shown in the figure, this measuring device 1 is inserted into the soil and used to measure the hydrogen concentration in the soil. That is, the present probe 4 is driven into the soil around the buried pipe, the amount of hydrogen generated around the buried pipe is measured from the flowing anticorrosion current, and an index of whether or not there is an influence by hydrogen embrittlement is obtained.

The configuration of the measuring device 1 will be described. The measuring device 1 includes a probe unit 5 disposed in an environment 3 in an over-corrosion-protected state, and a potentiostat unit 6 electrically connected to an electrode or the like disposed at the tip of the probe unit 5. Have been. And as shown in the figure, the probe unit 5
The upper end 5a is provided with an operation section 50 for an insertion operation. Also, the tip is formed at an acute angle for driving into the soil.

The probe unit 5 is an inner container 5a as an environment insertion container formed of the same material (iron) as the buried pipe 2.
, And the material is exposed at the outer peripheral portion. The inner surface of the container 5a is subjected to nickel plating 7 as a corrosion prevention film in order to reduce the influence of ionic current due to corrosion due to contact with an alkaline solution serving as an electrolytic solution contained therein. here,
The nickel film 7 is passivated and has hydrogen permeability. Further, inside the nickel film 7,
A Teflon coating 8 is provided to regulate the area of direct contact between the nickel film 7 and 1N sodium hydroxide, which is an alkaline solution contained in the container 5a. That is, by performing this processing, the area of the metal material through which hydrogen penetrating into the alkaline solution from the environment 3 passes becomes constant, and this area can be used as a requirement for calculating the amount of hydrogen described later.

Further, a reference electrode (Hg / HgO) 9 is provided in the alkaline solution, whereby the solution is maintained at a reference potential. In order to satisfy the above-mentioned requirements, as shown in FIG.
0 is electrically connected. Further, a counter electrode (Pt) 11 having iron serving as a simulated metal portion as a working electrode is disposed in an alkaline solution, and each cable end 12 is connected to the above-mentioned potentio stud. It is connected to the unit 6.

Hereinafter, a determination procedure for determining the state of excessive corrosion protection using the measuring apparatus 1 of the present invention will be described. (1) In the soil around the buried pipe, place the probe 5 of the measuring device.
Type. At this time, if the anticorrosion state of the buried pipe 2 is an over-corrosion prevention state, hydrogen is generated by electrolysis of water. Therefore, the atomic hydrogen enters the container 5a. Container 5a
The alkaline solution therein is maintained at 150 mV (vs. Hg / HgO) by setting the potentiostat section 6, and hydrogen atoms invading from the soil become hydrogen ions by the reaction of H → H ⁺ + e ⁻ . If this is the simulated metal part (Fe), it flows between the working electrode 5a and the counter electrode (Pt) 11. (2) Estimate the amount of hydrogen. Than the ion current flowing between the working electrode and the counter electrode to determine the amount of hydrogen C ₀ the following equation.

[0013]

(Equation 1)

(3) Judgment of over-corrosion prevention state By comparing the calculated amount of hydrogen with a predetermined amount of critical hydrogen, it is determined whether or not the material constituting the buried pipe 2 is greater than the critical amount of hydrogen affected by hydrogen. Is determined, and the degree of excessive corrosion protection of the environment is determined.

[Alternative Embodiment] In the above-described embodiment, an example in which the container 5a and the operation unit 50 are made of the same material, iron, is shown. However, a plurality of different materials are used for a single operation unit. A container 5a may be prepared, and the container 5a may be replaced and used according to the material of the buried pipe 2 (replacement of the container results in direct contact with the environment 3 such as soil). The simulated metal part will be replaced). Further, the majority of the container 5a may be made of plastic or the like, and a simulated metal body (constituting the simulated metal portion) having a corrosion prevention film at a predetermined portion may be configured to be detachable. In this case, it is convenient to configure the predetermined cross-sectional area into which hydrogen enters so as to match the cross-sectional area of the simulated metal body.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the drawings]

FIG. 1 is a diagram showing an apparatus configuration of a corrosion protection degree measuring apparatus.

FIG. 2 is a diagram showing a determination state of a degree of anticorrosion.

[Explanation of symbols]

 2 Buried metal body 3 Environment 5a Environment insertion container 7 Corrosion prevention film 9 Reference electrode 11 Counter electrode

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-52-152788 (JP, A) JP-A-3-188366 (JP, A) JP-A-52-121388 (JP, A) JP-A-49-1982 77692 (JP, A) JP-A-58-208654 (JP, A) JP-A-59-194052 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/416 G01N 17 / 04 G01N 27/26 351 JICST file (JOIS)

Claims (2)

(57) [Claims] An anticorrosion degree measuring device for measuring a hydrogen concentration in an environment (3) around an laid metal body (2) in a state of cathodic protection, which is disposed in the environment (3). An environment insertion container (5a) that is capable of storing an electrolyte maintained at a constant potential by a reference electrode (9), and a simulated metal part made of the same material as the laid metal body (2); At least a portion of the environment insertion container (5a) is provided in an externally exposed state, and a corrosion prevention film (7) is provided inside the simulated metal portion to prevent corrosion caused by contact with the electrolytic solution. An apparatus for measuring the degree of excessive corrosion prevention, wherein a counter electrode (11) is provided in a liquid, and the simulated metal part is configured as a working electrode for the counter electrode (11). 2. The method according to claim 1, wherein the simulated metal part is provided in the environment insertion container (5
2. The apparatus for measuring the degree of anticorrosion according to claim 1, wherein the apparatus is configured to be replaceable with respect to a).