JPH0219253B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a corrosion-proof split construction method for marine steel structures. (Prior Art) As is well known, steel materials are severely corroded in the marine environment, especially near the splash zone and tidal zone.
This is often the cause of shortening the service life of marine steel structures. For this reason, newly built marine steel structures are generally coated with thick-film special coatings, organic resin linings, and corrosion-resistant metal cladding. Some of the inventors previously published Japanese Patent Application Publication No. 58-29916.
In the publication, a three-layer structure is described, including an anti-corrosion layer as the bottom layer, which mainly acts as an anti-corrosion layer, a buffer layer to withstand shock as the middle layer, and a plate-like or sheet-like protective cover made of reinforced plastics or corrosion-resistant metal as the outermost layer. We proposed a corrosion protection construction method for marine steel structures that uses an integrally molded anticorrosion body that is molded in advance to a weight and size that is easy to work with. That is, as shown in FIG. 2, a concrete offshore bridge 1 is supported by columns 2 made of steel pipes. 3 is an anti-corrosion coating provided in the splash zone of the support column 2. FIG. 3 shows an example of an integrally molded anti-corrosion coating divided into two parts, in which a petrolatum-based anti-corrosion agent impregnated layer 6 + a foamed polyethylene buffer layer 5 + a glass fiber reinforced plastic protective layer 4 are attached to a prepared steel pipe pile 10 with bolts and nuts 8. 7 is a flange. According to research conducted by the present inventors, when corrosion is prevented using an integrally molded corrosion protector, the shape of the existing steel pipe pile that is the object to be protected is different from that at the time of manufacture, and distortion occurs due to a load greater than expected and the occurrence of rust. The surface shape often changes. Therefore, it is necessary to modify the shape of the anti-corrosion body so that it adheres closely to the steel pipe pile. (Problems to be Solved by the Invention) The present invention provides a corrosion-proof split construction method for marine steel structures that is excellent in corrosion protection in the splash zone, tidal zone, and submerged areas of existing steel pipe piles. (Means and effects for solving the problem) The present invention provides an integrally molded anti-corrosion body consisting of an anti-corrosion layer that performs an anti-corrosion effect and a buffer layer that brings the anti-corrosion layer into close contact with the surface of the steel material and has the effect of withstanding impact. It is characterized in that it is pre-molded and attached to an existing pile, and after the shape of the integrally molded anti-corrosion body is corrected, an insulating flange is brought into contact with a plate-shaped cover made of titanium or a titanium alloy, and then tightened with corrosion-resistant metal bolts. The invention will now be explained with reference to the drawings. First, in the present invention, the integrally molded anti-corrosion body includes (a) an anti-corrosion layer in contact with the steel surface, that is, a layer consisting of a petrolatum-based anti-corrosive agent, a tape impregnated with a petrolatum-based anti-corrosive agent, or a foam impregnated with a petrolatum-based anti-corrosive agent; and (b)
It is a corrosion protection body that has a two-layer structure consisting of a buffer layer made of plastic foam or the like, and is meant to be molded in advance as a single corrosion protection body. Such a corrosion protection body is hereinafter referred to as an integrally molded corrosion protection body. Next, materials that can be used for the integrally molded anticorrosion body used in the method of the present invention will be described. The lowest anti-corrosion layer consists of a paste containing petrolatum as its main ingredient and a corrosion inhibitor and a chemical agent that converts iron rust into a corrosion-resistant film such as tannic acid, and a non-adhesive tape made by impregnating a non-woven fabric such as nylon with the paste. Pastes and impregnated tapes of chemicals having water permeability, water repellency and corrosion resistance, or foams such as polyethylene, polyurethane and synthetic rubber impregnated with these chemicals are used. For the intermediate buffer layer, closed cell foam such as polyethylene or polyurethane, synthetic rubber foam, hydrophobic nonwoven fabric, or the like can be used. The method of attaching the integrally molded anti-corrosion body to the steel pipe pile used in the method of the present invention is, for example, as shown in Fig. 1a, by abutting an L-shaped insulating flange against a plate-shaped cover made of titanium or titanium alloy, and using corrosion-resistant bolts. Tighten. That is, in the figure, 5 is a foamed polyethylene buffer layer, which is an upper layer of the petrolatum anticorrosive agent-impregnated layer 6. The buffer layer 5 is protected by a titanium anti-corrosion cover body 4, which is in the form of a sheet and given a desired width and length. The cover main body 4 is formed with flanges 7, 7, and a water stop material 11 is interposed between the flanges 7, 7. The water stop material 11 is a foamed cushion material, and is made of an elastic sheet material such as foamed polyethylene. In the anti-corrosion cover used in the present invention, an L-shaped insulating flange 20 is brought into contact with a flange 7 and tightened with bolts 8 and nuts 9 made of stainless steel, for example. Preferably an insulating cap 1 is placed in the bolt hole.
2 and 12 are used together. This insulating cap 12 has an L-shaped flange 20,
A cylindrical cap long enough to penetrate the titanium flange 7 and contact the water stop material 11 is preferable, and by using such insulating caps 12, 12 together on the left and right flanges, the titanium seat cover main body 4 and bolt 8 are completely insulated, preventing corrosion due to contact between titanium and stainless steel. The materials for the insulating caps 12, 12 are as follows:
Plastic such as hard vinyl or insulating ceramic is suitable, and a cylindrical material having an appropriate inner diameter depending on the outer diameter of the bolt 8 may be used. Further, as shown in FIG. 1b, for example, a rust preventive agent such as petrolatum paste or asphalt is applied as a gap filler 13 between the titanium flanges 7 and the water stop material 11 to fill the gap. In particular, if the risk of so-called crevice corrosion of titanium and stainless steel is prevented, even better effects can be obtained. Furthermore, as shown in FIG. 1b, if a water stop plate 14 is provided between the titanium sheet cover bodies 4, 4 and the buffer layer 5 so as to be located at the lower part of the flange joint, it can be used to fill gaps, for example. Even if the agent 13 is omitted, water can be prevented from entering the inside of the anti-corrosion coating 3.
It can be prevented quite effectively. In this case, as the water stop plate 14, a titanium plate made of the same material as the titanium seat cover bodies 4, 4, or a hard plastic plate with excellent water stop properties can be used. In addition, when using a titanium plate, attach one side of the titanium plate to either one of the titanium seat cover bodies 4, 4 in advance as shown in Fig. 1b.
If it is attached by the welded portion 15 as shown in the figure, handling during assembly becomes easier. In this way, the present invention protects the anti-corrosion layer 6 and the buffer material 5 with the titanium cover main body 4, interposes the insulating material 11 between the flanges 7, 7, and molds the insulating flange 20 from, for example, fiber-reinforced plastic. Since the bolts are tightened after contacting the titanium flanges 7, 7, there is no direct contact between the bolts and the titanium flanges. That is, since electrochemical contact corrosion between the bolt and the titanium flange is prevented, corrosion resistance utilizing the durability of titanium is improved. Although the shape of the insulating flange is shown as an L-shape, it is not particularly limited as long as it reinforces the titanium flange. According to experiments conducted by the present inventors, the shape of the existing steel pipe pile, which is the object to be protected against corrosion, is different from that at the time of manufacture, and the shape of the existing steel pipe pile may become distorted or the surface shape may change due to a load greater than expected or the occurrence of rust. It is often changing. Therefore, after installing the integrally molded anti-corrosion body of the present invention, modifying its shape to bring it into close contact with the steel pipe pile, and then firmly tightening it with the anti-corrosion cover of the present invention is extremely effective in preventing corrosion of steel structures. The effects of the present invention will be illustrated in more detail with reference to Examples below. (Example)

[Table] As is clear from Table 1, the corrosion protection method for marine structures according to the present invention has excellent construction efficiency and the strength retention rate of the protective cover titanium sheet is extremely good. It can withstand the conditions, protect the anticorrosion layer and buffer layer for a long time, and protect marine structures from corrosion. (Effects of the Invention) As is clear from the above examples, the present invention provides a corrosion protection method that is more durable than the conventional method.
It can be provided by simple means, and the industrial effects are extremely significant.

[Brief explanation of drawings]

FIGS. 1a and 1b are partially enlarged explanatory views showing one embodiment of the present invention, FIG. 2 is an explanatory view of a conventional example, and FIG.
The figure is a schematic diagram showing the cross-sectional structure of the covering shown in FIG. 2. 1... Sand bridge, 2... Pillar, 3... Anti-corrosion coating,
4, 4...Titanium sheet cover body, 5...Buffer layer, 6...Petrolatum anticorrosive agent impregnated layer, 7,7
...Titanium flange, 8...Bolt, 9...Nut, 11...Water stop material, 12...Insulating cap, 1
3... Gap filler, 14... Water stop plate, 15...
Welding part, 20... L-shaped insulating flange.

Claims (1)

[Claims] 1. An integrally molded anti-corrosion body consisting of an anti-corrosion layer that has an anti-corrosion effect and a buffer layer that adheres the anti-corrosion layer to the surface of the steel material and has the effect of withstanding impact is pre-molded and attached to an existing pile, A corrosion-proof split construction method for a marine steel structure, which comprises: after correcting the shape of a molded corrosion-protection body, an insulating flange is brought into contact with a plate-shaped cover made of titanium or titanium alloy, and tightened with corrosion-resistant metal bolts.