Method for repairing heavily anti-corrosive steel material and heavily anti-corrosive repair steel material

Abstract

To provide a repair method for heavy duty corrosion-proof steel material allowing the heavy duty corrosion-proof steel material which has deteriorated or may deteriorate in corrosion-proof durability to be efficiently repaired to effectively extend corrosion-proof durability of the heavy duty corrosion-proof steel material.SOLUTION: A repair method for heavy duty corrosion-proof steel material comprises: a first step of exposing basis steel material of the heavy duty corrosion-proof steel material; a second step of cleaning a surface of the exposed basis steel material; a third step of forming a corrosion inhibitor layer on a surface of the cleaned basis steel material; a fourth step of covering a surface of the corrosion inhibitor layer with a woven fabric or nonwoven fabric resin sheet; and a fifth step of forming a waterproof resin layer on a surface of the resin sheet.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for repairing heavily corrosion-resistant steel materials and a heavily corrosion-resistant repaired steel material.

Background Art

[0002] For structures constructed in harbors, coastal areas, and offshore areas, steel materials (heavily corrosion-resistant steel materials) with heavy corrosion protection are usually used for the purpose of preventing corrosion caused by salt damage. As such heavily corrosion-resistant steel materials, various ones have been proposed so far, for example, those in which a chromate treatment layer, a urethane primer layer, and a urethane resin layer are laminated and formed on the surface of a base steel material (for example, Patent Document 1, etc.).

[0003] However, while the typical expected service life of harbor facilities is 50 years, it has become clear that many of the existing heavily corrosion-resistant steel materials have a corrosion protection durability life of only about 20 years.

[0004] On the other hand, when repainting and repairing the heavily corrosion-resistant steel materials used in existing structures, it has been difficult to repair the heavily corrosion-resistant steel materials to the same configuration as the original due to restrictions on the working space and scaffolding at the repair site.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to provide a repair method that can efficiently repair heavily corrosion-resistant steel materials with deteriorated or potentially deteriorated corrosion protection performance used in harbor facilities, etc., and can effectively extend the corrosion protection durability of the heavily corrosion-resistant steel materials.

[0007] Another object of the present invention is to provide a heavily corrosion-resistant repair steel material having excellent corrosion resistance durability.

Means for Solving the Problems

[0008] The method for repairing a heavily corrosion-resistant steel material according to the present invention for achieving the above object includes: a first step of exposing the base steel material of the heavily corrosion-resistant steel material; a second step of cleaning the surface of the exposed base steel material; a third step of forming a rust preventive agent layer on the surface of the cleaned base steel material; a fourth step of covering the surface of the rust preventive agent layer with a resin sheet of woven fabric or non-woven fabric; and a fifth step of forming a waterproof resin layer on the surface of the resin sheet.

[0009] In the method for repairing a heavily corrosion-resistant steel material having the above configuration, it is preferable that the waterproof resin layer is a layer made of any one of polyurethane resin, polyurea resin, and fiber reinforced plastic.

[0010] Also, in the method for repairing a heavily corrosion-resistant steel material having the above configuration, it is preferable that the resin sheet is a polyolefin-based woven fabric sheet or a polyolefin-based non-woven fabric sheet.

[0011] Also, in the method for repairing a heavily corrosion-resistant steel material having the above configuration, it is preferable that the thickness of the resin sheet is in the range of 0.2 mm or more and 0.6 mm or less.

[0012] Also, in the method for repairing a heavily corrosion-resistant steel material having the above configuration, it is preferable that the waterproof resin layer is formed by spray coating.

[0013] Also, according to the present invention, there is provided a heavily corrosion-resistant repair steel material characterized by including a base steel material, a rust preventive agent layer formed on the surface of the base steel material, a resin sheet of woven fabric or non-woven fabric covering the rust preventive agent layer, and a waterproof resin layer formed on the surface of the resin sheet. Agent

[0014] In the heavily corrosion-resistant repair steel material having the above configuration, it is preferable that the waterproof resin layer is a layer made of any one of polyurethane resin, polyurea resin, and fiber reinforced plastic. ​

[0015] Also, in the heavy anticorrosion repair steel material having the above structure, the resin sheet is preferably a polyolefin woven fabric sheet or a polyolefin non-woven fabric sheet.

[0016] Also, in the heavy anticorrosion repair steel material having the above structure, the thickness of the resin sheet preferably ranges from 0.2 mm to 0.6 mm.

Advantages of the Invention

[0017] According to the method for repairing a heavy anticorrosion steel material according to the present invention, it is possible to efficiently repair a heavy anticorrosion steel material whose anticorrosion performance has deteriorated or is likely to deteriorate, and it is possible to effectively extend the anticorrosion durability of the heavy anticorrosion steel material.

[0018] Also, according to the heavy anticorrosion repair steel material according to the present invention, excellent anticorrosion durability is achieved.

Brief Description of the Drawings

[0019]

Figure 1

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Figure 8

Embodiments for Carrying Out the Invention

[0020] The repair method of the heavy anti-corrosion steel material according to the present invention (hereinafter, may be simply referred to as "repair method") and the heavy anti-corrosion steel repair material will be described below, but the present invention is not limited to these embodiments at all. In addition, in this specification, "~" means including the numerical values before and after it as the lower limit value and the upper limit value.

[0021] Most of the conventional heavy anti-corrosion steel materials are those in which the surface of the base steel material is coated with polyethylene or polyurethane in the factory (pre-lining heavy anti-corrosion steel materials). Such pre-lining heavy anti-corrosion steel materials were transported to the installation sites of structures such as harbors and oceans and assembled as structures.

[0022] The pre-lining heavy anti-corrosion steel material PS1 in which the base steel material is coated with polyethylene generally has a structure in which a surface treatment layer 7, an adhesive layer 8, and a polyethylene coating layer 9a are laminated in this order from the surface of the base steel material 1 as shown in FIG. 7. Further, the pre-lining heavy anti-corrosion steel material PS2 in which the surface of the base steel material is coated with polyurethane generally has a structure in which a surface treatment layer 7 and a polyurethane coating layer 9b are laminated in this order from the surface of the base steel material 1 as shown in FIG. 8. The shape of the base steel material 1 is a conventionally known shape such as an H shape, a groove shape, a pipe shape, a sheet pile, or a plate.

[0023] The method and the heavy anti-corrosion repair steel material according to the present invention for repairing such a conventional heavy anti-corrosion steel material will be described with reference to FIGS. 1 and 2. FIG. 1 is a flowchart of the repair method according to the present invention, and FIG. 2 is a partial cross-sectional schematic view showing the surface structure of the repaired heavy anti-corrosion steel material (heavy anti-corrosion repair steel material).

[0024] As shown in FIG. 1, the repair method of the present invention has a first step to a fifth step. These steps will be described in order below. Note that the object of the repair method according to the present invention is not limited to the pre-lining heavy anti-corrosion steel material, and it can also be performed on the repaired heavy anti-corrosion steel material.

[0025] (First step) In the first step of the repair method according to the present invention, the base steel material 1 of the heavy anti-corrosion steel material is exposed. That is, the coating layer is removed from the surface of the heavy anti-corrosion steel material. As means for removing the coating layer, conventionally known means can be used. For example, cutting removal or the like can be used.

[0026] (Second step) In the second step, the surface of the base steel material 1 exposed by removing the coating layer is cleaned. The cleaning of the surface of the base steel material 1 is mainly the removal of rust. There is no particular limitation on the means for removing rust, and conventionally known means are used. For example, blast treatment in which an abrasive is high-pressure sprayed toward the surface of the base steel material 1, polishing with power tools such as sanders, power brushes, wire wheels, pneumatic hammers, or manual tools such as scrapers and wire brushes, pickling, and the like can be mentioned. Further, after surface cleaning, if necessary, dirt such as oil adhering to the surface of the base steel material 1 is removed with a cloth impregnated with an organic solvent.

[0027] (Third step) In the third step, a rust preventive agent is applied to the surface of the cleaned base steel material 1 to form a rust preventive agent layer 2. Since the surface of the base steel material 1 with a cleaned surface is likely to rust, it is desirable to apply the rust preventive agent as soon as possible. Grease or the like is preferably used as the rust preventive agent. The application amount of the rust preventive agent is generally preferably in the range of 300 g / m 2 ~800 g / m 2 of the range.

[0028] (Fourth step) In the fourth step, the surface of the rust preventive agent layer 2 is covered with a resin sheet 3 of woven or non-woven fabric. As a specific covering method, it is preferable that a strip-shaped resin sheet 3 is spirally wound around the surface of the rust preventive agent layer 2 for covering. By covering the surface of the rust preventive agent layer 2 with the resin sheet 3, the highly viscous oil component in the rust preventive agent penetrates into the voids of the resin sheet 3 and the resin sheet 3 adheres firmly to the base steel material 1. Further, the waterproof resin applied to the surface of the resin sheet 3 in the next step enters the voids of the resin sheet 3, and the waterproof resin layer 4 is firmly fixed to the surface of the resin sheet 3 by the so-called anchor effect.

[0029] Examples of the resin sheet 3 that can be used in the present invention include woven or non-woven sheets of polyolefin-based or polyester-based materials. Among these, polyolefin-based woven or non-woven sheets are preferred, and more preferably, a polypropylene woven sheet or a polypropylene non-woven sheet. The thickness of the resin sheet 3 is preferably in the range of 0.2 mm to 0.6 mm from the viewpoint of stably forming the waterproof resin layer 4 on the outer surface and allowing a part of the raw material of the waterproof resin layer 4 to penetrate through the resin sheet 3. Further, when the resin sheet 3 has such a thickness, it has flexibility, which facilitates the attachment work to the base steel material 1.

[0030] (Fifth step) In the fifth step, the waterproof resin layer 4 is formed on the surface of the resin sheet 3. The waterproof resin layer 4 is preferably a layer made of any one of polyurethane resin, polyurea resin, and fiber-reinforced plastic.

[0031] When the waterproof resin layer 4 is composed of a polyurethane resin or a polyurea resin, two liquids of an isocyanate and a polyol or two liquids of an isocyanate and an amine can be collided and mixed with a spray gun and applied to the surface of the resin sheet, which can reduce the working labor and shorten the working time. When spray coating using two liquids of an isocyanate and a polyol as the waterproof resin raw material, it is preferable to use, for example, the spray coating device SP shown in FIG. 6. In the spray coating device SP shown in FIG. 6, the isocyanate and the polyol are supplied from the drum can 61 and the drum can 62 to the device main body 60, respectively. The isocyanate and the polyol adjusted to a predetermined pressure in the device main body 60 are supplied to the spray gun G via the heating hose 63. Then, the isocyanate and the polyol are mixed in the spray gun G and sprayed onto the surface of the resin sheet 3 to form a polyurethane resin layer. For example, the discharge pressure from the device main body 60 of the spray coating device SP during spraying is about 14 MPa to 24 MPa, and the maximum liquid pressure temperature is about 90 °C. As such a spray coating device SP, for example, "H-XP3 Reactor" manufactured by GRACO is preferably used. If two liquids of an isocyanate and an amine are used as the waterproof resin raw material liquid, a polyurea resin layer is formed by the same operation.

[0032] On the other hand, when the waterproof resin layer 4 is composed of a fiber-reinforced plastic (FRP), a fiber sheet such as a glass fiber or a carbon fiber impregnated with a resin solution such as a polyester resin is attached to the surface of the resin sheet 3 to form an FRP layer. The waterproof function is enhanced as the fiber sheet impregnated with the resin solution is laminated and adhered to the surface of the resin sheet 3. Generally, the waterproof resin layer 4 made of FRP preferably has a laminated structure of two or three layers.

[0033] The thickness of the waterproof resin layer 4 is not particularly limited as long as the waterproof function is exhibited. Usually, when the waterproof resin layer 4 is made of polyurethane resin or polyurea resin, the range of 1.5 mm to 5.0 mm is preferable, and more preferably, the range of 2.0 mm to 4.0 mm. When the waterproof resin layer 4 is made of FRP, the range of 1.5 mm to 5.0 mm is preferable, and more preferably, the range of 2.5 mm to 3.5 mm. If the thickness of the waterproof resin layer 4 is too thin, the waterproof function and strength will be insufficient. On the other hand, if the waterproof resin layer 4 is too thick, the raw material cost will increase and it will not be economical.

[0034] The heavy anticorrosion repaired steel material repaired by the method described above will be described with reference to FIGS. 3 to 5. FIGS. 3 to 5 are cross-sectional views perpendicular to the longitudinal direction when the base steel material is an H-shaped steel.

[0035] (Repair Example 1) The heavy anticorrosion repaired steel material S1 shown in FIG. 3 is the simplest repaired heavy anticorrosion steel material. The heavy anticorrosion repaired steel material S1 has a rust preventive agent layer 2a coated with a rust preventive agent such as grease, a nonwoven fabric resin sheet 3a, and a polyurethane resin layer (polyurea resin layer) 4a laminated in this order on the surface of the H-shaped steel 1a that has been cleaned by removing rust and the like. Since the rust preventive agent layer 2a and the polyurethane resin layer (polyurea resin layer) 4a have strong non-affinity, it is usually difficult to apply and form the polyurethane resin layer (polyurea resin layer) 4a on the rust preventive agent layer 2a. However, due to the intervention of the nonwoven fabric resin sheet 3a, an anchor effect is exerted, and a strong laminated structure of the rust preventive agent layer 2a and the polyurethane resin layer (polyurea resin layer) 4a is formed on the surface of the H-shaped steel 1a.

[0036] (Repair Example 2) In Repair Example 1 shown in FIG. 3, each layer was formed along the surface shape of the H-shaped steel 1a. Generally, it is difficult to wrap and cover the concave portion 11 of the H-shaped steel 1a with the nonwoven fabric resin sheet 3a or to uniformly and efficiently apply and form the polyurethane resin layer (polyurea resin layer) 4a on both corners in the direction perpendicular to the longitudinal direction of the bottom surface of the concave portion 11.

[0037] Therefore, in the double anti-corrosion repair steel material S2 shown in Fig. 4, a filling member FM having a cross-sectional shape substantially the same as that of the concave portion 11 of the H-shaped steel 1a is filled in the concave portion 11 of the H-shaped steel 1a, and the H-shaped steel 1a is formed into a columnar body with a square cross-section, so that it is easy to wind and coat the non-woven resin sheet 3a and to apply and form the polyurethane resin layer (polyurea resin layer) 4a. This will be specifically described below.

[0038] First, an anti-rust agent such as grease is applied to the surface of the H-shaped steel 1a to form an anti-rust agent layer 2a. Next, a paper tape 5a impregnated with petrolatum is wound around the surface of the anti-rust agent layer 2a. The petrolatum-impregnated paper tape 5a enhances the anti-rust property and moisture barrier of the H-shaped steel 1a. Then, a filling member FM with a square cross-section is inserted into the concave portion 11 of the H-shaped steel 1a. As a result of inserting the filling member FM into the concave portion 11 of the H-shaped steel 1a, the surface where the concave portion 11 of the H-shaped steel 1a is formed and the externally exposed surface of the filling member FM become substantially the same plane, and the cross-sectional shape of the H-shaped steel 1a becomes square. Since it is desirable that the filling member FM is lightweight, expanded polystyrene is preferably used as the filling member FM.

[0039] Next, the non-woven resin sheet 3a is spirally wound around the surface of the petrolatum-impregnated paper tape 5a and the externally exposed surface of the filling member FM. As described above, since the filling member FM is filled in the concave portion 11 and the H-shaped steel 1a has become a columnar body with a square cross-section, the winding and coating of the non-woven resin sheet 3a can be easily performed.

[0040] Thereafter, in the same manner as in Repair Example 1, a polyurethane resin layer (polyurea resin layer) 4a is formed on the surface of the non-woven resin sheet 3a. Also in this step, since the filling member FM is filled in the concave portion 11 and the H-shaped steel 1a has become a columnar body with a square cross-section, the polyurethane resin layer (polyurea resin layer) 4a can be uniformly and easily formed by spray coating.

[0041] (Repair Example 3) The heavy anti-corrosion repair steel material S3 shown in Fig. 5 uses an FRP layer 4b as a waterproof resin layer. An anti-rust agent such as grease is applied to the surface of the H-shaped steel 1a to form an anti-rust agent layer 2a. Next, a petrolatum-impregnated paper tape 5a is wound around the surface of the anti-rust agent layer 2a. The petrolatum-impregnated paper tape 5a enhances anti-rust and blocks air and moisture. Then, a filling member FM with a square cross-section is inserted into the recess 11 of the H-shaped steel 1a. As a result of inserting the filling member FM into the recess 11 of the H-shaped steel 1a, the surface of the H-shaped steel 1a where the recess 11 is formed and the externally exposed surface of the filling member FM become substantially the same plane, so that the H-shaped steel 1a becomes a columnar body with a square cross-section.

[0042] Next, a petrolatum-impregnated paper tape 5b is wound around the surface of the petrolatum-impregnated paper tape 5a and the externally exposed surface of the filling member FM. As described above, since the H-shaped steel 1a filled with the filling member FM in the recess 11 becomes a columnar body with a square cross-section, the petrolatum-impregnated paper tape 5b can be easily wound. Then, a non-woven fabric resin sheet 3a is spirally wound around the surface of the petrolatum-impregnated paper tape 5b. After that, an FRP layer 4b is formed on the surface of the non-woven fabric resin sheet 3a. The FRP layer 4b is formed by impregnating a fiber sheet such as a glass fiber or a carbon fiber with a resin solution such as a polyester resin and attaching it to the surface of the non-woven fabric resin sheet 3a. In the heavy anti-corrosion repair steel material S3, the fiber sheets are laminated in three layers. Thereby, a high waterproof function is exhibited.

[0043] (Others) The heavy anti-corrosion repair steel material described above is an H-shaped steel, but it is not limited thereto, and the base steel material may be a conventionally known one such as a grooved shape, a tubular shape, a sheet pile, or a plate. Also, a primer layer or the like may be formed between the layers formed on the surface of the base steel material as necessary.

Industrial Applicability

[0044] According to the repair method of the present invention, it is possible to efficiently repair a heavy anti-corrosion steel material whose corrosion resistance has deteriorated or is likely to deteriorate, and it is possible to effectively extend the corrosion durability of the heavy anti-corrosion steel material.

Explanation of Signs

[0045] 1 Base steel material 1a H-shaped steel 2 Rust preventive agent layer 2a Rust preventive agent layer 3 Resin sheet 3a Non-woven fabric resin sheet 4 Waterproof resin layer 4a Polyurethane resin layer (polyurea resin layer) 4b FRP layer 5a, 5b Petrolatum-impregnated paper tape 11 Recess FM Filling member

Claims

1. A method for repairing heavily anti-corrosive steel, a first step of exposing the base steel of the heavily anti-corrosive steel, a second step of cleaning the surface of the exposed base steel, a third step of forming an anti-rust agent layer on the surface of the cleaned base steel, a fourth step of coating the surface of the anti-rust agent layer with a resin sheet of woven fabric or non-woven fabric having a thickness in the range of 0.2 mm or more and 0.6 mm or less, a fifth step of forming a waterproof resin layer made of polyurethane resin or polyurea resin on the surface of the resin sheet, The method for repairing heavily anti-corrosive steel, characterized by comprising the above steps.

2. The method for repairing heavily anti-corrosive steel according to claim 1, wherein the resin sheet is a polyolefin-based woven fabric sheet or a polyolefin-based non-woven fabric sheet.

3. The method for repairing heavily anti-corrosive steel according to claim 1 or 2, wherein the waterproof resin layer is formed by spray coating.

4. A base steel, an anti-rust agent layer formed on the surface of the base steel, a resin sheet of woven fabric or non-woven fabric covering the anti-rust agent layer, a waterproof resin layer formed on the surface of the resin sheet, having the above layers, wherein the thickness of the resin sheet is in the range of 0.2 mm or more and 0.6 mm or less, and the waterproof resin layer is polyurethane resin or polyurea resin The heavily anti-corrosive repaired steel characterized by the above.

5. The heavily anti-corrosive repaired steel according to claim 4, wherein the resin sheet is a polyolefin-based woven fabric sheet or a polyolefin-based non-woven fabric sheet.

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