JP2667186B2 - Electric corrosion prevention method for underground metal pipes and electric corrosion prevention structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for preventing electrolytic corrosion of a metal pipe buried underground and a structure for preventing electrolytic corrosion obtained by the method.

[Conventional technology]

Conventionally, as shown in FIG. 5, a ready-made sacrificial anode in which a metal pipe (1) buried in the ground is dug out, a sacrificial anode material (11a) such as Mg is wrapped with a backfill (11b) and put in a cotton bag. (1
1) was installed in the borehole (12) and connected to the metal pipe (1) by the lead wire (13), and then the borehole (12) was backfilled.

The backfill (11b) acts to lower the ground electric resistance of the sacrificial anode (11) and prevent the sacrificial anode (11) from rising, and to uniformly elute the sacrificial anode material (11a).

[Problems to be solved by the invention]

However, since the length of the sacrificial anode (11) is generally 1 m or more, the drill hole (12) must be made quite large in order to be able to install the sacrificial anode (11). A great deal of expense, labor, and construction are required for restoration work, treatment of excavated sediment and backfilled sediment, construction becomes difficult due to road structure and traffic conditions, and lead wire connection work is troublesome. There was room for improvement.

An object of the present invention is to enable the installation of a sacrificial anode to be performed with a small amount of excavation work and without the need for lead wire connection work.

[Means for solving the problem]

The characteristic feature of the first invention is that a sacrificial anode material is mixed with a backfill material to prepare a flowable electrode material, and the soil is located in the vicinity of a metal pipe buried in the ground, A discharge portion of the injector inserted into the container, the injector injects the electrode material into the soil near the metal tube, and brings the injected electrode material into contact with the metal tube in a conductive state. The effect is as follows.

(Operation)

In other words, the electrode material is injected into the soil near the metal tube by the injector inserted from the ground into the soil in a state where it is in contact with the metal tube, and the conductive material is transferred between the sacrificial anode material contained in the electrode material and the metal tube. In a possible manner, the action of the sacrificial anode material prevents electrical contact of the metal tube.

Also, by the action of the backfill material contained in the electrode material,
The ground electric resistance of the sacrificial electrode material can be reduced, and the elution of the sacrificial electrode material can be made uniform. As a whole, the electrolytic corrosion of the metal tube can be sufficiently prevented as in the above-described conventional technology.

Therefore, the excavation site can be made extremely small for inserting the injector, and the amount of excavated soil can be greatly reduced compared to the above-mentioned conventional technique, and excavation work, backfill work, treatment of excavated earth and backfill earth and sand. The cost and labor required for such operations can be sufficiently reduced, and the construction period can be sufficiently reduced.

In addition, since there is no need to perform the work of connecting the sacrificial anode material to the metal tube with a lead wire, the cost and labor can be reduced and the construction period can be more sufficiently achieved.

[Means for solving the problem]

The characteristic feature of the second invention is that a backfill material having fluidity and conductivity is prepared by mixing a conductive material with a backfill material, and an injection pipe having a sacrificial anode material is inserted into the soil from the ground, Dispensing the backfill material into the soil near the metal tube and the sacrificial anode material by using the injection tube to position the discharge portion of the injection tube in soil located near the metal tube buried in; The backfill material is brought into contact with the metal tube and the sacrificial anode material in a conductive state, and the operation and effect are as follows.

(Operation)

In other words, the backfill material is injected from the ground into the soil near the metal tube by the injector having the sacrificial anode material in contact with the metal tube and the sacrificial anode material, and the action of the conductive material contained in the backfill material is performed. As a result, electric conduction can be conducted between the metal tube and the sacrificial anode material, and the action of the sacrificial anode material prevents contact of the metal tube.

In addition, by the action of the backfill material included in the backfill material, while reducing the grounding electric resistance of the sacrificial anode material,
The elution of the sacrificial electrode material is made uniform, and as a whole, the electrolytic corrosion of the metal tube can be prevented in the same manner as in the above-mentioned prior art.

Therefore, the excavation site can be made extremely small for inserting the injection pipe, and the work of connecting the sacrificial anode material to the metal pipe with the lead wire can be eliminated, reducing the cost and labor and shortening the construction period. It can be achieved as well as the invention.

〔The invention's effect〕

As a result, construction work to install sacrificial anode material underground to effectively prevent electrolytic corrosion of underground metal pipes is economical,
Electric corrosion of metal pipes buried underground, which can be executed in a short time, with a small construction footprint and a small road damage area, and can be carried out easily, for example, with little restrictions on road structure and traffic conditions. The prevention method and the anti-corrosion structure were obtained.

〔Example〕

 Next, an embodiment of the first invention will be described.

As shown in FIG. 1 (a), a pavement (A) pierces a pavement road from the ground to form a small hole (2) extending from the ground surface to the vicinity of a metal pipe (1) buried underground. As the drilling machine (A), an appropriate known drilling means such as a jet jet drilling type or a rotary drill type is used.

As shown in FIG. 1 (b), the injector (3) is inserted into the small hole (2), and the discharge part (3a) of the injector (3) is located in the soil near the metal pipe (1). .

Then, a fluid electrode material (4) obtained by mixing a sacrificial anode material with a backfill material is injected into the soil near the metal tube (1) by the injector (3), and the injected electrode material (4) Is brought into contact with the metal tube (1) in a conductive state.

Thereafter, as shown in FIG. 1 (c), the injector (3) is recovered, the small hole (2) is backfilled, the perforated portion (5) of the paved road is repaired, and the construction is completed.

The electrode material (4) is prepared in advance. As the sacrificial anode material, for example, a material having a lower potential than the metal tube (1), such as Mg, Al, Zn, or an alloy thereof, is powdery or granular. It is used in the form of short lines or small blocks.

The backfill material is appropriately selected from known materials, and for example, the following (a) to (g) can be used.

(B) Mixture of bentonite, stone, sodium sulfate and water (b) Water glass (c) Mixture of water glass and water (d) Mixture of water glass, bentonite, stone and sodium sulfate (e) Carbon paste (f) Mixture of acrylic acid or acrylate and water (g) Conductive polymer or composite conductive polymer material Next, examples of the second invention will be described.

As shown in FIG. 2 (a), an injection pipe (6) having a sacrificial anode material (6a) is inserted into a small hole (2) formed by the same means as in the above-mentioned embodiment, and the sacrificial anode material (6a) is inserted. Is located in the soil near the metal pipe (1) buried underground.

Then, a backfill material (8) obtained by mixing a backfill material with a conductive material is poured into the soil near the metal pipe (1) by an injection device (7) connected to the injection tube (6). The injected backfill material (8) is brought into conductive contact with the metal tube (1) and the sacrificial anode material (6a), and the sacrificial anode material (6a) is surrounded by the backfill material (8). Let

Thereafter, as shown in FIG. 2 (b), the injection device (7)
And a part of the injection pipe (6c) is recovered, the small hole (2) is backfilled, the perforated part (5) of the pavement road is restored, and the construction is completed.

The backfill material (8) is prepared in advance, and the same backfill material as that used in the above-described embodiment is used, and the conductive material is used for metal powders, short wires, small lumps, and the like. .

(Another embodiment)

 Next, another embodiment will be described.

In the first invention, when the electrode material (4) is injected into the soil, the insertion position of the injector (3), the discharge direction of the electrode material (4), and the like can be appropriately changed. As shown in (a), the injector (3) is inserted above the metal tube (1) to discharge the electrode material (4) downward,
As shown in FIG. 2 (b), the injector (3) may be inserted into both sides of the metal tube (1) to discharge the electrode material (4) from the left and right toward the metal tube (4). Alternatively, the small hole (2) may be omitted and the injector (3) may be inserted into the soil with a suitable pushing device.

In the second aspect of the present invention, when the injection pipe (6) having the sacrificial anode material (6a) is inserted into the soil, the insertion position, the insertion method,
For example, as shown in FIG. 4, the injection tube (6) can be inserted above the metal tube (1) or the sacrificial anode material (6a) can be electrically connected to the metal tube (1). Or the injection pipe (6) can be inserted into the left and right of the metal pipe (1), or the injection pipe (6) can be inserted into the soil without a small hole (2) by a suitable pushing device. . When the sacrificial anode material (6a) is brought into contact with the metal tube (1), for example, a polishing machine such as a sand blast device or a rotary polishing machine is inserted into the small hole (2) to remove the coating layer of the metal tube (1). It is desirable to perform polishing and polishing.

The type of the metal pipe (1) buried underground does not matter, and can be, for example, a metal pipe for gas, water, hot water, an electric cable, or the like.

[Brief description of the drawings]

FIGS. 1 (a) to 1 (c) are illustrations of construction procedures in an embodiment of the first invention. FIGS. 2 (a) and 2 (b) are illustrations of construction procedures in the embodiment of the second invention. FIGS. 3 (a) and 3 (b) are illustrations of another embodiment of the first invention. FIG. 4 is an explanatory view of another embodiment of the second invention. FIG. 5 is an explanatory view of a conventional example. (1) Metal tube (3) Injector (3a) Discharge unit (4) Electrode material (6) Injection tube (6a)
Sacrificial anode material, (6b) ... discharge section, (8) ... backfill material.

Claims (5)

(57) [Claims] 1. A fluid electrode material (4) is prepared by mixing a sacrificial anode material with a backfill material, and is placed in the soil located near a metal tube (1) buried in the ground from above the ground. Position the outlet (3a) of the injector (3) inserted in the soil,
The injector (3) injects the electrode material (4) into the soil near the metal tube (1), and the injected electrode material (4) is electrically connected to the metal tube (1). How to prevent electrolytic corrosion of metal pipes buried underground. 2. A metal electrode (4) in which a fluid electrode material (4) obtained by mixing a sacrificial anode material with a backfill material is injected from the ground into the vicinity of a metal tube (1) in soil. An anti-corrosion structure for metal pipes buried underground that are in conductive contact 3. A backfill material (8) having fluidity and conductivity is prepared by mixing a conductive material with a backfill material, and an injection pipe (6) having a sacrificial anode material (6a) is placed in the soil from the ground. The discharge part (6a) of the injection pipe (6) is located in the soil located near the metal pipe (1) buried in the ground,
The backfill material (8) is injected into the soil near the metal tube (1) and the sacrificial anode material (6a) by the injection tube (6), and the injected backfill material (8) is injected into the metal tube. A method for preventing electrolytic corrosion of an underground metal pipe which is brought into contact with (1) and a sacrificial anode material (6a) in an electrically conductive state. 4. An injection tube (6) having a sacrificial anode material (6a).
Is placed near the underground metal pipe (1) in a state where it is inserted from the ground, and a fluid and conductive backfill material (8) obtained by mixing a conductive material with a backfill material is charged into the injection pipe ( 6)
In the state of being injected into the vicinity of the metal pipe (1) and the sacrificial anode material (6a), the electric power of the underground-embedded metal pipe which is in conductive contact with the metal pipe (1) and the sacrificial anode material (6a). Food prevention structure. 5. The metal tube (1) wherein said sacrificial anode material (6a) is
The structure for preventing electrolytic corrosion of a metal pipe buried underground according to claim 4, wherein the metal pipe is in conductive contact with the metal pipe.