JPH0431030B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to anticorrosion electrodes for various metals and alloys, especially for metal members in freshwater or seawater, metals buried in soil, and reinforcing bars in concrete. This invention relates to a robust and easy-to-handle anticorrosion anode used for cathodic protection of steel frames, etc.

(Prior art and its problems) Conventionally, in order to prevent corrosion of metal parts and metal piping that are underwater, underground, concrete, etc.,
Anti-corrosion coating is used to isolate insulating components from the environment, but with this coating alone, metals often become exposed due to the formation of pinholes over a long period of time or changes in paint components, making it difficult to achieve complete corrosion protection. I couldn't do it.

In recent years, cathodic protection has been adopted to achieve complete corrosion protection. Cathodic protection is a corrosion protection method based on stabilizing the metal to be protected, such as iron, by negatively polarizing it, and this state continues. It is an extremely important anti-corrosion measure because its anti-corrosion effect continues for as long as possible.

The cathodic protection methods currently in use can be roughly divided into two types: galvanic protection and cathodic protection.The former uses a sacrificial anode, which dissolves itself and stabilizes the metal to be protected as a negative electrode. Therefore, there is a drawback that the anode needs to be replaced periodically and complicated maintenance work is required. On the other hand, the latter cathodic electrolytic protection uses an insoluble anode to connect a DC power supply between the metal to be protected and supply electricity, thereby maintaining the metal to be protected in a negative state and stabilizing it. The cathodic protection has the advantage that the corrosion protection continues as long as the power supply is not stopped, and is widely used despite the disadvantage that it requires large-scale equipment.

Cathodic protection continues to be improved in terms of the material of the anode used, but the electrode and the conductor for energizing the electrode are manufactured separately, and even when installed at a predetermined location, it is difficult to install the electrode separately. The amount of work required is enormous because the installation usually spans a long distance or over a vast area, and the connection between the electrode and the conductor at the time of installation is insufficient. There is a drawback that the connection portion may not be sufficiently insulated from the outside world, making that portion susceptible to corrosion. Furthermore, the energizing voltage is usually 20 to 60V.
There is also the problem that depending on the base material, the breakdown voltage may be reached and melted.

(Object of the Invention) The present invention has been made to solve the above-mentioned problems, and provides a corrosion protection electrode that has sufficient durability and ease of construction and maintenance for use in cathodic protection. The purpose is to

(Means for Solving the Problems) The present invention involves closely adhering a cylindrical insoluble metal electrode coated with an electrode active material around a partially cut-out flexible conductive wire coated with an insulating material. , a conductive connecting body is buried in the cutout to connect the conductive wire and the metal electrode, and a protrusion that is substantially parallel to the insulating material and has a tapered inner surface is formed at the end of the metal electrode. A first sealing material made of a corrosion-resistant metal having a structure is attached, and a ring-shaped metal piece having substantially the same shape as the space is engaged with the first sealing material in the space between the tapered part and the outer surface of the insulating material. The electrode is press-fitted with a second sealing material made of a corrosion-resistant metal.

The present invention will be explained in detail below.

In the insoluble metal electrode of the present invention, electrodes for cathodic protection tend to be roughly handled at installation sites, so the electrode base needs to be made of a material that can withstand such handling and has sufficient corrosion resistance. For example, it is preferable to use valve metals such as titanium, zirconium, niobium, and tantalum, or alloys containing these metals as main components. Then, a coating mainly composed of an electrode active material such as a platinum group metal and/or its oxide is formed on the substrate to form an electrode. The platinum group metal and its oxide may be Pt, Ir, Os, Pd, Ru, Rh, or any of these oxides. In addition, conventionally used ferrite and other electrode materials may be used. However, it is desirable to use a platinum group metal and/or its oxide because of its long life.

In the present invention, a flexible conducting wire coated with an insulating material is passed through the inside of the cylindrical electrode and electrically connected to integrate the cylindrical electrode and the conducting wire in advance, thereby eliminating the need for assembly at the installation site. shall be. The connection may be made by any method; however, a part of the insulating material of the conductive wire is cut to expose the core wire, and a conductive connecting body made of copper or the like is fitted into the cut. It is most preferable to contact the core wire, bring the outer edge of the connecting body and the insulating material into contact with the inner edge of the cylindrical electrode, and fix each member to each other by an appropriate method such as pressing.

The connection part including the conductive connection body needs to be isolated from the outside world because corrosion is likely to occur when the connection body made of copper or the like comes into contact with moisture. Therefore, in the present invention, it is necessary to isolate the connection part from the outside world. A pair of sealing materials are provided at contact points between both ends of the cylindrical electrode and the insulating material to reliably isolate the connection portion from the outside world.

Of the pair of sealing materials, the first sealing material is fixed to both ends of the cylindrical electrode by welding, integral molding, etc. so that its inner edge contacts the insulating material. When one end of the cylindrical electrode is closed, the sealing material is attached to the other end that is not closed. A protrusion that is substantially parallel to the insulating material and has a tapered portion is formed in the first sealing material, and a space between the protrusion and the insulating material has a shape that is substantially the same as that of the space. A ring-shaped metal piece for sealing is accommodated, and the ring-shaped metal piece is press-fitted into the space by a second sealing material to completely ensure close contact between the cylindrical electrode and the insulating material at the connection portion. is securely isolated from the outside world. The reason why metal is used as the sealing material in the present invention is that a perfect seal cannot be achieved even if other materials such as resin are used.

Therefore, according to the present invention, there is provided a corrosion-protective electrode that has sufficient durability against deterioration of the connection portion due to intrusion of gases generated in the soil, seawater, etc., and damage to the connection portion due to earth pressure, water pressure, etc. It becomes possible to do so.

Further, in the present invention, by configuring the pair of sealing materials with the same metal as the cylindrical electrode, it is also possible to prevent macrocell corrosion due to dissimilar metals when electricity is not applied.

Furthermore, in the anticorrosion electrode of the present invention, inactive metals are exposed to an electrolytic atmosphere in a commonly used high voltage (20 to 60V) environment, and the voltage applied to the exposed metal portions may cause corrosion and dissolution. This corrosion can be prevented by coating the sealing material with the same electrode active material as the cylindrical electrode.

Furthermore, by coating the sealing material with a substance that is less active than the electrode active material of the cylindrical electrode, the above-mentioned corrosion can be prevented, and consumption of the electrode active material of the sealing material can be reduced, resulting in an economical solution. It also becomes possible to perform corrosion protection.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below based on one embodiment shown in the accompanying drawings, but the present invention is not limited to this embodiment.

(Example) The drawing is a partially cutaway front view showing an example of the anticorrosive electrode according to the present invention.

The conductive wire 1 extending in the vertical direction includes a large number of small diameter copper wires,
A core wire 2 made of bundles of aluminum wires etc. and a flexible insulating material 3 such as synthetic resin coated around the core wire 2
A portion of the insulating material 3 of the conductive wire 1 is completely removed in the circumferential direction to form an incision 4. Note that the incision may not be made entirely in the circumferential direction but may be made in part.

A doughnut-shaped conductive connector 5 having the same shape as the space formed by the cutout 4 is fitted into the cutout 4, and the connector 5 is installed so as to be in contact with the periphery of the insulating material 3. The cylindrical electrode 6 is electrically connected to the core wire 2 by contacting the inner surface of the cylindrical electrode 6.

At both upper and lower ends of the cylindrical electrode 6, a first
A sealing material 7 is fixed, and the first sealing material 7 includes a donut-shaped main body 8 and a protrusion 9 extending from the main body 8 in a direction opposite to the cylindrical electrode 6 and substantially parallel to the insulating material 3. The inner surface of the protrusion 9 is tapered, and the outer tip of the protrusion 9 is provided with a male thread.

A wedge-shaped ring-shaped metal piece 10 having approximately the same shape as the space is provided in the space between the protrusion 9 and the insulating material 3.
is accommodated, and the ring-shaped metal piece 10 is
A donut-shaped second sealing material 11 whose female threaded portion is screwed into the male threaded portion of the sealing material 7 is press-fitted into the space, and is inserted between the cylindrical electrode 6 and the insulating material 3. is maintained in close contact. Note that the metal piece 10 may be divided into two or more pieces in the vertical direction.

The outer surface of the cylindrical electrode 6 is coated with an electrode active material containing, for example, a platinum group metal and/or its oxide, thereby serving as an anode for cathodic protection.

Has the above shape, thickness 1.0mm, outer diameter 12mm, length
Two indium oxide coated titanium cylindrical electrodes with a total diameter of 300 mm have a finished outer diameter of 9.5 mm and a conductor outer diameter of 4.5 mm.
A conductive wire having a cross-sectional area of 14 mm ² is passed through the conductive wire, and each of the electrodes and the conductive wire are electrically connected by a conductive connecting body. using sealant,
A ring-shaped metal piece coated with indium oxide was press-fitted into the space between both sealants. The average resistance of the electrode
It was inserted into a 2500Ωcm underground well with a diameter of 75 mm and a depth of 14 m, and after insertion, the well was filled with bentonite mud. This electrode was placed in a carbon mesh steel pipe (diameter 150 mm,
60m long, 3 pieces).

When efforts were made to maintain the potential of the steel pipe at -1.0V for six months, the supply voltage was approximately 25V and the current value was 5.5A.

During this period, the anode potential remained unchanged at 1.6V, and no inflow of water or soil from the sealed portion or elution of the internal conductive wire was observed.

(Effects of the Invention) The anticorrosion electrode according to the present invention includes a cylindrical insoluble metal electrode that is tightly attached around a conducting wire covered with an insulating material, and a pair of sealing materials attached to both ends of the cylindrical electrode. By press-fitting a ring-shaped metal piece using the pair of sealants into the space formed by the pair of sealants, the space between the cylindrical electrode and the insulating material is completely sealed. The connecting portion between the cylindrical electrode and the conducting wire is completely isolated from the outside world, thereby reliably preventing deterioration of the connecting portion due to gases generated in the soil, seawater, and earth pressure. .

Therefore, firstly, in the anti-corrosion electrode of the present invention, the durability of the connecting portion, which is often lacking in durability, can be improved, thereby extending the life of the entire electrode. The number of times edible electrodes need to be replaced can be significantly reduced, and the number of personnel and costs required for maintenance can be reduced.

Second, because the cylindrical electrode and the conductor are integrated and standardized, they can be mass-produced at the factory without any problems with the connections, and they can be handled like normal conductors at the construction site. Because it is possible to
In particular, work efficiency on site will be greatly improved.

Thirdly, since the conductor wire is flexible, it can be placed in the optimal position according to the shape of the counter electrode, regardless of the location where it is installed.This allows the anode and cathode to be as close as possible, reducing the resistance between the two electrodes. The applied voltage is also reduced, making it possible to save energy.

[Brief explanation of drawings]

The drawing is a partially cutaway front view showing one embodiment of the anticorrosive electrode according to the present invention. 1... Conductor wire, 2... Core wire, 3... Insulating material,
4... Cutting portion, 5... Connection body, 6... Cylindrical electrode,
7...First sealing material, 8...Main body, 9...Protrusion, 1
0... Ring-shaped metal piece, 11... Second sealing material.

Claims (1)

[Scope of Claims] 1. A cylindrical insoluble metal electrode coated with an electrode active material is tightly attached around a partially cut out flexible conductive wire covered with an insulating material, and a conductive wire is attached to the cut part. A first made of a corrosion-resistant metal, which connects the conductive wire and the metal electrode by embedding a connecting body, and has a protrusion at an end of the metal electrode that is substantially parallel to the insulating material and has a tapered portion formed on the inner surface. a second ring-shaped metal piece made of a corrosion-resistant metal, which is provided with a sealing material, and which engages with the first sealing material a ring-shaped metal piece having approximately the same shape as the space in the space between the tapered portion and the outer surface of the insulating material;
Anti-corrosion electrode made by press-fitting with sealant. 2. The anti-corrosion electrode according to claim 1, wherein the sealing material is made of the same metal as the insoluble metal electrode. 3. The anti-corrosion electrode according to claim 1 or 2, wherein the sealing material is coated with the same electrode active material as the electrode active material coated on the insoluble metal electrode. 4. The anti-corrosion electrode according to claim 1 or 2, wherein the sealing material is coated with an electrode active substance that is less active than the electrode active substance coated on the insoluble metal electrode.