JP6948290B2 - Anticorrosion method for steel structures - Google Patents

Description

The present invention relates to an anticorrosion method for steel structures, and more particularly to an anticorrosion method suitable for suppressing corrosion of steel members in a closed cross section.

Significant corrosion damage may occur on the inner surfaces of steel structures such as signs, lighting columns, steel pipe piles, and steel balustrades of urban viaducts. It is said that this damage is often caused mainly by rainwater containing chlorides such as sea salt and antifreeze agents, and dew condensation water staying inside the members for a long period of time.

In such a structure, anticorrosion measures such as painting and plating are generally applied to the outer surface, but it is difficult to apply plating and painting to the inside of the existing structure without defects. For this reason, various measures are required for anticorrosion measures on the inner surface of the closed portion of the steel structure. For example, Patent Document 1 discloses a technique for preventing corrosion inside an existing steel pipe. The technique disclosed in Patent Document 1 cuts a steel pipe, fills the inside with fine particles of a metal (base metal) having a potential lower than that of the steel pipe constituent member, and restores the cut steel pipe. It is a thing.

According to such a technique, the fine metal particles filled inside the steel pipe serve as an anode to protect the inner surface of the steel pipe from cathodic protection, and the fine particles dissolved in the anode form a hydroxide to form a protective film, thereby preventing corrosion. Is said to increase.

Japanese Unexamined Patent Publication No. 2000-129473

According to the technique disclosed in Patent Document 1, it is certainly considered that there is a certain effect on the corrosion protection inside the steel structure. Here, the technique disclosed in Patent Document 1 is considered to be particularly effective for relatively small structures such as signs and lighting columns. On the other hand, in the case of a large structure such as a viaduct made of steel balustrade, a large amount of fine metal particles are used, which may increase the weight increase rate of the structure itself. In addition, due to its characteristics, it cannot be handled as a unit, and there is a problem that it is not easy to handle.
Therefore, an object of the present invention is to provide an anticorrosion method for a steel structure, which can be handled well and the rate of weight increase of the structure can be suppressed to a low level.

In the anticorrosion method for a steel structure according to the present invention for achieving the above object, a first opening having an opening facing upward of the steel structure is provided, and the first opening is provided on a side portion of the steel structure. An anode material having a second opening smaller than the portion and having water-retaining fibers arranged on the outer periphery of a metal rod having a lower potential than the steel structure is arranged inside the steel structure from the first opening. At the same time, the second opening is sealed by fixing the metal rod and the steel structure in a state of conducting the connection through the second opening.

Further, in the anticorrosion method for steel structures having the above-mentioned characteristics, it is preferable that the outer periphery of the metal rod is provided with spines that pierce the water-retaining fibers. By having such a feature, it is possible to prevent the position of the water-retaining fiber from being displaced with respect to the metal rod.

According to the anticorrosion method for steel structures having the above-mentioned characteristics, the handleability can be improved and the weight increase rate of the structure can be suppressed to a low level.

It is a perspective view which shows the state which inserted and arranged the anode material which concerns on embodiment into a cylindrical steel structure. It is a partial cross-sectional view for demonstrating the structure of the anode material which concerns on embodiment. It is a figure which shows the modification of the anode material which concerns on embodiment. It is a figure which shows the flow of the anticorrosion method of inserting and arranging an anode material into a small steel structure. It is a perspective view for demonstrating the anticorrosion method for inserting and arranging an anode material into a large steel structure. It is a top view which shows the example of the case where a plurality of anode materials are inserted and arranged in a large steel structure.

Hereinafter, embodiments of the anticorrosion method for steel structures of the present invention will be described in detail with reference to the drawings. In addition, the embodiment shown below is a part of the embodiment suitable for carrying out the anticorrosion method of the steel structure of the present invention, and the form of each element and the order of construction are as long as the function is not deviated. Can be regarded as a part of the present invention even if the above is changed.

[Anode material]
First, the configuration of the anode material 10 applied to the present invention will be described with reference to FIGS. 1 and 2. The anode material 10 according to this embodiment is basically composed of a metal rod 12 and a water-retaining fiber 14. The metal rod 12 may serve as a sacrificial anode and may be made of a metal having a potential lower than that of the steel structure 20 to be subjected to the anticorrosion treatment. When the steel structure 20 is made of iron (Fe), the metal rod 12 may be made of aluminum (Al), zinc (Zn), an aluminum alloy, a magnesium alloy, or the like. Considering ease of processing, raw material cost, etc., it is desirable to use an aluminum-zinc alloy (Al-Zn) or the like.

The water-retaining fiber 14 may be any member as long as it has water-retaining properties, and may be, for example, cloth, paper, knitted fabric, non-woven fabric, or the like. Further, the water-retaining fiber 14 can include a fiber having a hydrophilic functional group. _{Specifically, it may have a hydrophilic functional group such as -SO3H, -COOH, -NH 3} , -CONH ₂ , -CHO, -SH, -OH in the fiber or on the fiber surface. This is because fibers having such a composition can retain water in or between the fibers. Examples of the fiber having a hydrophilic functional group include rayon, cotton, vinylon, nylon, wool, and acrylate.

The anode material 10 according to the embodiment is configured by arranging the water-retaining fibers 14 having the above-mentioned structure on the outer periphery of the metal rod 12 having the above-mentioned structure. The means for arranging the water-retaining fibers 14 is not particularly limited, and as shown in FIG. 2, the sheet-shaped water-retaining fibers 14 may be wound around the outer circumference of the metal rods 12, or the metal rods 12 may be arranged. May be sandwiched between sheet-shaped or block-shaped water-retaining fibers 14 (the form is not shown).

At the time of use, the water-retaining fiber 14 of the anode material 10 having such a structure is impregnated with the electrolytic solution. The electrolytic solution may be one that generates an anticorrosion current between the steel structure 20 to be anticorrosion and the metal rod 12, that is, one that causes the movement of ions, but in reality, it is in rainwater or the atmosphere. Moisture is responsible for the function.

The metal rod 12 of the anode material 10 according to the embodiment is connected to the steel structure 20 by the conductive member 16. The conductive member 16 may be a flexible conducting wire or the like, but in the present embodiment, the conductive member 16 is an element that plays a role as a support for positioning the anode material 10 by being fixed to the steel structure 20. It is said.

[Modification example]
In this way, when the water-retaining fiber 14 is arranged on the outer circumference of the metal rod 12, the outer circumference of the metal rod 12 may be provided with the spines 12a as shown in FIG. A plurality of spines 12a may be arranged radially with the metal rod 12 as the base end, and the arrangement form thereof is not particularly limited. By providing the spines 12a on the outer periphery of the metal rod 12 and arranging the spines 12a so as to entangle (pierce) the water-retaining fibers 14, the positions of the metal rods 12 and the water-retaining fibers 14 are less likely to be displaced. Therefore, when the metal rods 12 are arranged vertically, it is possible to prevent the water-retaining fibers 14 from being biased toward the lower half of the metal rods 12 due to the action of their own weight. Note that FIG. 3 shows the spines 12a formally needle-shaped, but the spines 12a are other than needle-shaped as long as they can exert the effect of preventing the displacement of the water-retaining fibers 14. It can also be in the form of.

[Application to steel structures 1]
Next, an anticorrosion method for installing the anode material 10 having the above characteristics on the steel structure 20 will be described. First, an example will be described in which the steel structure 20 is relatively small, such as a sign or a lighting column, and has a cylindrical cross-sectional shape.
When the steel structure 20 is an existing structure as shown in the sign shown in FIG. 4 (A), as shown in FIG. 4 (B), a region on the upper side of the corrosion protection target region in the steel structure 20 is cut. Then, the first opening 22 is formed. This is because, in the case of sign columns and lighting columns, the progress of corrosion at the root portion where water tends to stay tends to increase, and it is less necessary to provide corrosion protection to the entire structure. Next, a second opening 24 for fixing the conductive member 16 is formed on the side wall portion in the lower half portion of the cut steel structure 20. Here, the first opening 22 is an opening for inserting the anode material 10 into the steel structure 20. On the other hand, the second opening 24 is an opening for inserting and fixing the conductive member 16. Therefore, the second opening 24 is smaller than the first opening 22.

Next, as shown in FIG. 4B, the anode material 10 is inserted and arranged inside the steel structure 20. At this time, the water-retaining fibers 14 arranged on the outer periphery of the metal rod 12 are densely arranged so as to be in contact with the inner wall of the steel structure 20 when the anode material 10 is arranged inside the steel structure 20. .. By using the water-retaining fiber 14 as the member arranged between the metal rod 12 and the steel structure 20, the flexible fiber adheres well to both members, and it is possible to enhance the anticorrosion effect. Become. The arrangement range of the water-retaining fibers 14 is not limited, but by covering the metal rod 12 in the longitudinal direction, it is possible to exert an anticorrosion effect in a wide range.

The conductive member 16 is arranged so as to penetrate the second opening 24, and is fixed in a state where conductivity with the steel structure 20 is ensured via a nut 18 or the like. Therefore, the second opening 24 is sealed together with the fixing of the conductive member 16. As described above, in the present embodiment, the conductive member 16 serves as a support for the metal rod 12. Therefore, by fixing the conductive member 16 to the steel structure 20 through the second opening 24, the anode material 10 including the metal rod 12 is positioned inside the steel structure 20.

In such an arrangement, the water-retaining fiber 14 is impregnated with the electrolytic solution so that the anticorrosion current is between the steel structure 20 and the metal rod 12 with the metal rod 12 as the anode and the steel structure 20 as the cathode. Will occur. As a result, an oxidation reaction occurs in the metal rod 12 and a reduction reaction occurs in the steel structure 20, and it is possible to prevent corrosion of the inner wall surface of the steel structure 20.

As shown in FIG. 4D, the upper half of the steel structure 20 cut to form the first opening 22 after the anode material 10 is installed inside the steel structure 20 as described above. By joining to the lower half of the steel structure 20, the steel structure 20 is returned to its original state.

[Application to steel structures 2]
Next, an anticorrosion method when the anode material 10 having the above-mentioned characteristics is applied to a large structure such as a steel balustrade of a viaduct will be described.
The steel structure 20 of the present embodiment is a box body having a rectangular cross section like a viaduct balustrade as shown in FIG. When the steel structure 20 has such a form, a first opening 22 for inserting the anode material 10 is formed in the top plate portion. Further, as in the above embodiment, a second opening 24 for inserting and fixing the conductive member 16 is formed in the lower half of the side wall of the box body. If the top plate portion can be removed, the first opening 22 may be formed by removing the top plate. Here, as shown in FIG. 5, when the aspect ratios of the cross-sectional shapes are different and the structure is so-called wide, as shown in FIG. 6, a plurality of anode materials 10 are arranged with respect to one steel structure 20. Therefore, the first opening 22 can be one opening having a large area, but a plurality of the second openings 24 are provided according to the number of the anode materials 10 to be arranged.

The anode material 10 is inserted from the first opening 22 and fixed to the steel structure 20 so as to seal the second opening 24 via the conductive member 16 in the same manner as in the above embodiment. Here, as shown in FIGS. 5 and 6, the water-retaining fiber 14 may be pressed and deformed so that the contact surface of the water-retaining fiber 14 with the steel structure 20 becomes a flat surface. Further, when a plurality of anode materials 10 are arranged, the arrangement interval is such that the gap between the anode materials 10 arranged close to each other (the gap between the water-retaining fibers 14) is small (ideally, there is no gap). Then it is good.

It is desirable that the arrangement interval of the anode material 10 is appropriately adjusted according to the installation location and usage conditions of the steel structure 20. The water-retaining fiber 14 may be arranged in a range that covers the arrangement range in the axial direction of the metal rod 12, as in the above embodiment. After the insertion and placement of the anode material 10 is completed, the first opening 22 is sealed in the same manner as in the above embodiment. In the case of this form, the top plate may be returned to its original position.

According to such a construction method, even if the steel structure 20 is a large structure such as a viaduct balustrade, the weight increase rate of the balustrade itself due to anticorrosion measures can be suppressed. Further, since the anode material 10 is composed of a simple structure and material such as the metal rod 12 and the water-retaining fiber 14, the anode material 10 can be inexpensive and easy to handle.

When the anode material 10 provided with the water-retaining fiber 14 is arranged on the steel structure 20 as in the above embodiment, the substrate is adjusted inside the steel structure 20 before the anode material 10 is arranged. It is good to apply. The substrate adjustment may be any work as long as it removes rust and dirt adhering to the inside of the steel structure 20, and there is no problem in anticorrosion even with about 2 types of keren. By adjusting the substrate inside the steel structure 20, the anticorrosion effect can be enhanced.

10 ………… Anode material, 12 ………… Metal rod, 12a ………… Thorn, 14 ………… Water-retaining fiber, 16 ………… Conductive member, 18 ………… Nut, 20 ………… Steel structure, 22 ……… 1st opening, 24 ……… 2nd opening.

Claims (2)

A first opening having an opening facing upward of the steel structure is provided, and a second opening smaller than the first opening is provided on the side of the steel structure.
An anode material in which water-retaining fibers are arranged on the outer periphery of a metal rod having a lower potential than that of the steel structure is arranged from the first opening inside the steel structure and through the second opening. A method for preventing corrosion of a steel structure, which comprises sealing the second opening by fixing the metal rod and the steel structure in a conductive state. The anticorrosion method for a steel structure according to claim 1, wherein the outer periphery of the metal rod is provided with spines that pierce the water-retaining fibers.

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