JP2003260754A - Heavy corrosion preventive coated steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heavy corrosion preventive coated steel which does not require repair and does not suffer deterioration of bonding even in an environment of severe corrosion and wave. <P>SOLUTION: In the heavy corrosion preventive coated steel formed by coating a corrosion preventive layer on a steel material surface, a projection is preliminarily provided at a coating edge part position of the steel product, and the corrosion preventive layer are formed on a prepared surface layer including the projection material. Then, even in a use under a salt water environment for a long period of time, peeling of the corrosion preventive layer can be controlled in comparison with the conventional heavy corrosion preventive coated steel and a stationary structure which is excellent in productivity and corrosion prevention is provided inside. Consequently, in the coated steel having a coated edge part such as a sheet pile, though decrease of adhesive strength between the coating and the steel is generated, there is scarecely a necessity for mending due to a barrier effect of the corrosion preventive coating, the coated steel can be used for a long period of time. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel structure such as steel sheet pile, steel pipe sheet pile or the like, which has long-term anticorrosion property when external corrosion protection is required due to severe corrosive environment such as pier or revetment of harbor / river. The present invention relates to a heavy-duty anticorrosion coated steel material that ensures high reliability, and can prevent the exfoliation of the coating even when adhesion deterioration of the coating from the end portion occurs, and thus is highly reliable and suitable for long-term use.

[0002]

2. Description of the Related Art Corrosion-resistant coating is applied to steel materials such as marine steel structures used in severely corrosive environments.
Heavy anticorrosion coating is effective. When long-term durability of several decades is required, it has excellent anticorrosion properties such as electrical insulation and chemical resistance, and heavy-duty anticorrosion using inexpensive resin such as polyolefin or polyurethane as coating material. Coated steel is being manufactured. With a heavy anticorrosion coating,
Long-term adhesion durability is ensured by combining a special steel material such as a base treatment and a primer treatment as described in JP-A-3-23527 with an anticorrosion coating.

[0003]

In many cases, the heavy anticorrosion coating is used only in the severely corroded portion mainly in the ocean tidal zone. Further, when a structure is formed by fitting like a steel pipe sheet pile or a steel sheet pile, the steel material surface may be exposed due to scratches during construction even if the fitting portion is painted. Around the exposed steel material part, adhesion deterioration easily progresses against a sound heavy-duty anticorrosion coating, and repair is usually required, but there is a problem that it is difficult to find and repair construction scratches in actual work.

On the other hand, even if the adhesive strength between the steel material and the coating is lowered in water, if the thickness of the anticorrosion coating is several mm, water, oxygen,
The supply of substances that promote corrosion such as ions is small, and the corrosion rate is extremely small compared to non-corrosion-resistant steel materials, so the corrosion-preventing function can be maintained. Therefore, even if the adhesive strength deteriorates due to a scratch or the like, the anticorrosion coating is not damaged, and the anticorrosion function is maintained unless a large amount of peeling occurs. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 10-192778, repairing with a polyethylene steel sheet pile has been proposed, but when the anti-corrosion property of the tack itself and the anticorrosive resin is polyurethane, the tack is difficult. There is such a problem. Further, since repairing requires a large amount of money, there has been a demand for a product that requires less repairing even in an environment such as severe corrosion and waves and has a relatively small problem of adhesion deterioration.

The present invention has been made in order to meet such a demand, and provides a heavy anticorrosion coated steel material which requires less repair even in an environment such as severe corrosion and waves and has a comparatively less problem of adhesion deterioration. Is an issue.

[0006]

The gist of the present invention for solving the above problems is as follows. (1) In a heavy anticorrosion coated steel material formed by coating an anticorrosion layer on the surface of a steel material, a projection is provided in advance at the coating end position of the steel material, and the anticorrosion layer is provided on the base treatment layer including the projection. The heavy-corrosion-coated steel material characterized in that (2) The heavy anticorrosion coated steel material according to (1), wherein a cover is provided on the protrusion.

When the heavy anticorrosion coating is formed by coating as described above, the fixing structure preliminarily subjected to the base treatment is provided on the steel material so that the fixing structure can be included inside the coating, and there is a problem of productivity. Few. As a result, even if the adhesive force between the coating and the steel material deteriorates, the coating is prevented from floating from the steel material, and the fixed structure is also covered with the anticorrosion coating.
It is possible to provide an anticorrosion-coated steel material which is excellent in long-term anticorrosion property without impairing the fixing function due to corrosion.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, when a heavy anticorrosion layer is formed by coating on the surface of a steel material, a protrusion shape is formed in advance on the coated end portion of the steel material, and then the surface treatment and coating are performed to form the protrusion. It is a heavy anticorrosion coated steel material having a structure containing a protrusion that has been subjected to a surface treatment for fixing the anticorrosion coating by performing the heavy anticorrosion coating.

Since the projections provided on the steel structure are covered with an anticorrosion coating, they may be ordinary steel materials, but steel materials having a nobler potential than the steel structure body are used. Further, since the tip of the protrusion is a portion where the coating is easily scratched, a resin cover for protecting the exposure of the protrusion may be provided separately. The shape of the protrusion may be any shape as long as the coating can be physically fixed, but it is desirable that the bubbles are less likely to remain inside during coating. An example of the present invention in which a bolt is used as a fixing structure is shown in FIG. 1 as a sectional view of a fixing portion.

As shown in the sectional view of FIG. 1, the present invention is a heavy anticorrosion coated steel material having a structure in which the heavy anticorrosion coating 3 is fixed by the projections 4 fixed to the steel material 1. In order to ensure long-term durability, the steel material 1 and the protrusions 4 are subjected to a base treatment and a primer treatment 2. Further, FIG. 2 shows a cross-sectional view in the case where the resin cover 5 is provided in order to prevent the steel material from being exposed due to a collision with the protruding portion or the like.

When applying the coating fixing structure by the projection to the steel sheet pile, the coating end portion in the claw direction is coated with the flange end portion and the valley surface with respect to the coating on the crest surface as shown in the sectional view of FIG. In the above, in the part close to the claw portion at the tip, it is arranged linearly in the length direction. From the function of fixing the covering, it is better to have a narrow pitch between the protrusions, but the work becomes complicated, so it is 10 to 50 cm.
The degree is appropriate. When a protrusion is provided on the lower end of the cover, it is arranged linearly along the flange and the web.

When applied to a steel pipe sheet pile, the shape of the claw is L-
An example of T is shown in the sectional view of FIG. Similarly, in the case of PP, a fixing projection is provided on the steel pipe body. Not the nails,
The reason why the protrusion is provided on the main body portion is that the nail portion is likely to be damaged or deformed during construction. Protrusions are arranged linearly in the length direction of the steel pipe. From the function of fixing the covering, it is better to have a narrow pitch between the protrusions, but the work becomes complicated, so it is 10 to 50 cm.
The degree is appropriate. Further, it is preferable that the lower end portion of the coating is linearly arranged along the steel pipe body.

[0013]

<Example 1> Two FSP-VL type steel sheet piles having a length of 10 m were used, and an 8M bolt made of SUS316 was arc-studd with a 25 cm pitch at the flanges of the ridges, valleys, and claw coating ends. Welded. Further, two bolts were welded to the web at the lower end of the coating and one bolt was welded to each of the left and right flanges. The height of the bolt after welding was adjusted to be less than 5 mm. After that, grid blasting was performed as a surface treatment for the steel material surface including the bolts to remove scales and the like, and then a chromate treatment agent of silica chromate system was applied and dried to perform the surface treatment. After that, as a primer, a paint containing baked kaolin clay fine powder and a rust preventive pigment added as a pigment to a one-component moisture-curable urethane resin with an isocyanate-terminated prepolymer is used as a paint.
It was applied by spraying and cured to a film thickness of 60 μm. Then, the main component of polybutadiene polyol containing fine powder of kaolin clay and the two-component curing urethane elastomer of the curing agent of crude MDI were mixed on the surface with a mixer and spray-coated to give a conventional polyurethane heavy-corrosion coating having a thickness of 3 mm. The periphery of the bolt fixed by welding is coated with a thickness of about 6 mm so that the bolt is completely covered with the polyurethane anticorrosion layer, and a heavy anticorrosion coated steel material having a protrusion fixing structure inside the coated end portion, which is an embodiment of the present invention, is manufactured. did.

<Example 2> Since a long-term test of 10 years or more is required to reproduce the state in which the anticorrosion layer is adhesively deteriorated,
Here, in order to reproduce the adhesion deterioration in a simulated manner for a comparative test to confirm the effect of the protrusions, a coated steel sheet pile that is subjected to only blasting as a base treatment and not subjected to a base treatment such as a chromate treatment or a primer treatment is used. A heavy-corrosion-coated steel material was produced in the same manner as in Example 1 to accelerate the decrease in the adhesive strength between the anticorrosion layer and the steel material.

<Embodiment 3> A steel pipe sheet pile having 600A LT claws is linearly provided at a 20 cm pitch in the vicinity of the claws on one side of the sheet pile.
M SUS304 stud bolts are welded and fixed, and a hard resin cap nut is attached to the tip, and the height of the tip is 7
I made it less than mm. After that, a grid blast treatment is applied as a base treatment to remove scales and the like, and then a urethane resin primer mixed with a rust preventive pigment is used in an amount of 30 to 6
It was applied by spraying and cured to a film thickness of 0 μm.
Next, a two-component cured urethane elastomer was mixed on the surface with a mixer and spray-coated to give a 3 mm thick heavy anticorrosion coating. Around the protrusions welded and fixed, a coating of about 6 mm was applied so that the bolts were completely covered with polyurethane, and a heavy corrosion-resistant coated steel material having a protrusion fixing structure inside the coated end portion was manufactured according to an embodiment of the present invention.

<Comparative Example 1> Mountains are prepared in the same manner as in Example 1,
The valley steel sheet pile was spray-coated by mixing the main component of the polybutadiene polyol containing the kaolin clay fine powder and the curing agent of the crude MDI with a two-component curing urethane elastomer without spraying the surface with a mixer. A resin-coated steel material was prepared in which the polyurethane anticorrosion coating did not adhere strongly to the steel material.

<Comparative Example 2> In the same manner as in Example 1, a mountain or valley steel sheet pile was not subjected to a base treatment for accelerating adhesion deterioration, and 2 parts of a polybutadiene polyol base compound and a crude MDI curing agent were used. Liquid hardening urethane elastomer was mixed with a mixer and spray-painted to prepare a 3 mm thick polyurethane-coated steel material. The flange portion of this steel sheet pile was struck from above the FRP contact plate along the flange, and the exposed portion of the rivet head after driving was tacked with a clay-like epoxy resin and a plastic cap. This corresponds to a repair of the conventional heavy anticorrosion coated steel sheet pile disclosed in JP-A-10-192778. However,
Polyurethane cracking was observed at several places, and we also tried tacking on the web part, but because the thickness of the steel material was so thick that the tack did not penetrate the steel material, we could not hit the tack on the web.

[0018] A coated steel sheet pile having a set of peaks and valleys formed by the above method and a steel pipe sheet pile were exposed to the coast for 5 years. After the marine exposure test, the polyurethane coating was removed and the corrosion of the steel surface and tacks or weld projections was investigated. The results are shown in Table 1. Corrosion was not observed in Example 1 in which the projections were entirely covered with the polyurethane coating, whereas in the case of the tack in Comparative Example 2, the cap might be disengaged due to the influence of waves, and corrosion was progressing. . In addition, Comparative Example 2
As can be seen from the manufacturing process of No. 3, it was impossible to tack the steel sheet pile web as the thickness of the steel material increased. Further, the average corrosion amount of the bare steel sheet pile in the underwater portion for 5 years was 0.15 mm / y, while the coated steel sheet pile of Example 2 showed a decrease in adhesive strength, but the lower coating portion There was no corrosion that could measure the thickness, and the anticorrosion function was maintained.

[0019]

[Table 1]

[0020]

EFFECTS OF THE INVENTION When a heavy anticorrosion layer is formed by coating on the surface of the steel material of the present invention, a projection is provided in advance at the coating end position of the steel material, and a base treatment including the projection is further performed. Heavy-duty anti-corrosion coated steel with heavy anti-corrosion coating has its projection fixing structure covered with anti-corrosion coating including undercoating, so it is difficult for corrosion to occur even during long-term use. It is fixed and the peeling of the coating hardly occurs. As a result, even if the adhesive strength of the coating is reduced in the steel material having the coated end portion, the progress of peeling is suppressed and long-term use is possible.

[Brief description of drawings]

FIG. 1 shows an example of a cross-sectional view of a fixing structure portion in a heavy anticorrosion coated steel material having a projection structure for fixing the coating of the present invention inside the coating.

FIG. 2 shows an example of a cross-sectional view of a fixing structure portion in a heavy anticorrosion coated steel material having a protrusion structure having a resin cover at the tip for fixing the coating of the present invention inside the coating.

FIG. 3 shows an example of a cross-sectional view of a fixing structure portion when the projecting structure for fixing the coating of the present invention is applied to a heavy anticorrosion coated steel sheet pile.

FIG. 4 shows an example of a cross-sectional view of a fixing structure portion when the projecting structure for fixing the coating of the present invention is applied to a heavy anticorrosion coated steel pipe sheet pile.

[Explanation of symbols]

1 steel 2 Base treatment and primer layer 3 double anticorrosion layer 4 Projection structure that fixes heavy corrosion protection 5 Resin cover that covers the tip of the protrusion 6 steel sheet pile 7 Steel pipe sheet pile

Front Page Continuation (51) Int.Cl. ⁷ Identification code FI Theme Coat (reference) E02D 31/06 E02D 31/06 C (72) Inventor Shinichi Funatsu 1 Kimitsu, Chiba, Chiba Prefecture Kimitsu, Nippon Steel Corp. F-term in the ironworks (reference) 2D018 BA00 2D041 AA02 BA07 DB02 2D049 FB03 FB12 FB14 FE02 4F100 AB03A AK51B AK51C AL09C BA03 BA10A BA10C CC00B CC00C DB01 EJ65B GB90 JB02C JK06 BA15BA0221K04 JL00 AB02 4K04

Claims (2)

[Claims] 1. A heavy anticorrosion coated steel material formed by coating an anticorrosion layer on the surface of a steel material, wherein a projection is provided in advance on the coated end position of the steel material, and the anticorrosion layer is provided on the base treatment layer including the projection. Heavy-corrosion-coated steel material characterized by having. 2. The heavy anticorrosion coated steel material according to claim 1, wherein the projection is provided with a cover.