JPH0651916B2 - Repair method for damaged part of steel anticorrosion coating - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for repairing a damaged portion of an anticorrosion coating layer of a tubular or plate-shaped steel material anticorrosion coated with polyolefin.

[Conventional technology]

Steel pipes, steel pipe sheet piles, or steel sheet piles that are anticorrosion coated with polyolefin in offshore steel structures or buried pipelines, etc., may be damaged by the anticorrosion coating layer during local transportation, driving, or burial. When this damage breaks the anticorrosion coating layer and reaches the steel surface, a repairing method considering corrosion protection of the steel surface is required.

For example, as shown in JP-A-61-170586, after filling the damaged portion of the anticorrosion coating layer with a filler so as to have the same level as the anticorrosion coating surface, the repair member is thermocompression-bonded, and the outer circumference of the repair member is further increased. There is a method of thermocompression bonding a reinforcing sheet.

Further, as disclosed in Japanese Patent Laid-Open No. 63-199885, there is a repair method in which a damaged portion of an anticorrosion coating layer is filled with a room temperature curing type resin and is protected with an adhesive tape.

[Problems to be Solved by the Invention]

By the way, although these repairing methods can exert the anticorrosion function structurally, they have the following problems in the field construction. One of them is that the anticorrosion coating layer is polyolefin,
There is no suitable filler that adheres to the anticorrosion coating layer at room temperature, and it is easy to trap air or water at the boundary between the anticorrosion coating layer and the steel surface of the damaged portion when filling the filler in the damaged portion. It becomes a weak point. Another is that it is difficult to adhere or adhere the protective material such as repair material or adhesive tape to the damaged part without gap, and there is no way to confirm that the protective material adheres or adheres to the damaged part without gap. .

The present invention provides a method for repairing a damaged portion of a coating layer, which solves the above problems and improves the corrosion resistance of the repaired portion.

[Means for Solving the Problems]

The present invention, in repairing a damaged portion that reaches the steel surface of an anticorrosion coating layer of a steel material anticorrosion coated with polyolefin, first installs a metal piece having a base potential with respect to iron on the damaged portion steel surface, and It is characterized by filling a filler with a filler, and further spreading a repair sheet on it, and a metal piece having a base electric potential with respect to iron is placed at the boundary between the corrosion-resistant coating layer and the steel surface of the damaged portion. , There is room for the filler to adhere to the steel surface in the center of the damaged steel surface, and a metal piece having a base electric potential with respect to iron has a width of 1 mm or more and has a size of the damaged portion. It is a method of repairing a damaged portion of a steel material anticorrosion coating layer having a sheet shape or a linear shape with a thickness of less than / 3 and a thickness of 50 to 1000 μm.

[Action]

As an anticorrosion method for steel materials in water, an electrocorrosion method in which a metal having a base electric potential with respect to iron such as zinc and aluminum is brought into contact with steel materials is well known. In these conventional cathodic protection methods, the shape and attachment method of the anticorrosion material suitable for the damaged portion of the anticorrosion coating layer of steel material have not been solved yet.

The present invention will be described in detail below together with its operation.

FIG. 1 is a drawing showing an example of the configuration of the present invention. In the figure, 1 is a steel material, 2 is a polyolefin coating layer, 4 is zinc,
A metal piece having a base electric potential with respect to iron, such as aluminum, 5 is a filler filled in the damaged portion, and 6 is a repair sheet.

As the metal piece 4 of zinc, aluminum, or the like, a metal or an alloy having a base potential with respect to iron, such as magnesium, manganese, chromium, titanium, or an alloy thereof, can be used.

This metal piece 4 is installed at the boundary between the steel surface of the damaged portion and the anticorrosion coating layer 2, and further, a doughnut-shaped sheet in which the central portion of the metal piece 4 is hollowed so that the filler 5 can adhere to the steel surface of the damaged portion, Alternatively, it is preferably formed into a wire. In this case, the metal piece 4
Width of 1mm or more, less than 1/3 of the size of damaged part is good, 1m
If it is less than m, the workability is poor, and if it is 1/3 or more of the size of the damaged portion, there is no room for bonding the filler 5. The thickness of the metal piece 4 is 50 ~
1000 μm is good, and if it is less than 50 μm, the workability is poor.
If it is more than m, the contact between the metal piece 4 and the steel surface of the damaged portion becomes poor.
Further, in order to improve the contact between the metal piece 4 and the steel surface of the damaged portion, a metal piece 4 coated with an electrically conductive adhesive may be used.

As the filler 5, epoxy, polyester, urethane, silicone or adhesive sealant, bituminous material, petroleum-based wax, etc., which can be used at room temperature, can be used, and the steel has excellent corrosion resistance and viscosity as a filler. Things are good. In the case of a wet environment locally, an underwater curable resin such as epoxy or polyester can be used.

As the repair sheet 6, it is desirable to use the same material as the steel anticorrosion coating layer. It can be processed into a sheet of one kind or a combination of two kinds of polyolefin, cross-linked polyolefin and modified polyolefin, and can be bonded and repaired by thermocompression bonding. However, depending on the local environment, the heating and pressure bonding work may be difficult, and it is possible to wind an adhesive tape or cover it with a glass fiber reinforced plastic (FRP) sheet. Adhesive tapes that can be used include tapes made by impregnating non-woven cloth with bituminous material, petroleum wax, etc., or adhesives applied to nylon, polyethylene, rubber, etc., and FRP can be epoxy, polyester, polypropylene, etc. A sheet-shaped product obtained by impregnating glass fiber with the above resin can be used.

Furthermore, FIGS. 2 and 3 show typical examples of the repair method of the present invention for an actual offshore steel structure. That is, FIG. 2 shows the damaged portion 3 of the anticorrosion coating layer of the steel pipe repaired, and FIG. 3 shows the damaged portion 3 of the anticorrosion coating layer of the steel sheet pile repaired.

〔Example〕

 The effects of the present invention will be specifically described below with reference to examples.

Steel pipe coated with 3 mm thick polyolefin (diameter 800 m
A mound with a diameter of about 30 mm was made to reach the steel surface with a grinder, and the polyolefin coating layer of the damaged portion was further ground to an angle of 135 degrees with respect to the steel surface to form the damaged portion.

As a metal piece, a 100 μm thick zinc sheet with a diameter of 30 mm and a width of 5 m
It was formed into a donut shape with an m (hole diameter 20 mm) and was attached to the damaged steel surface with a conductive adhesive. Next, the viscosity of the damaged part is 10,000
Poise's room temperature curing type epoxy resin was filled to the same level as the polyolefin coating layer. After the epoxy resin of the filling material was hardened by touch with the fingers (in a non-sticky state), the surface of the filling portion was flattened with sandpaper so as to be at the same level as the coating layer. Further, a repair sheet having an adhesive layer disposed on one side of the crosslinked polyolefin sheet and having a thickness of 1.5 mm and a diameter of 120 mm was thermocompression bonded with a gas burner for about 3 minutes to prepare a repair test piece.

A plurality of these repair test pieces were prepared, and a salt water immersion test was performed to confirm the anticorrosion performance of the repair part, and the adhesiveness of the repair sheet of the repair part and the corrosion state of the steel surface of the damaged part were investigated. In addition, in order to promote the corrosion deterioration of the repaired part, the temperature of the saltwater immersion water is set to 80
It carried out at 60 ° C. The results are shown in Table-1.

From this result, with respect to the damaged part of the steel material that is anticorrosion-coated with polyolefin, the electrocorrosion effect of the zinc sheet installed on the damaged part steel surface works effectively, and the repair method of the present invention is excellent in anticorrosion property. Show. Further, it can be understood that the damaged steel surface is in a corrosive environment even if the adhesiveness of the repair sheet does not deteriorate with time.

[Advantage of the Invention] According to the present invention, in a damaged portion of a steel material that is anticorrosion coated with polyolefin, it is possible to easily and reliably perform anticorrosion repair and enhance the anticorrosion effect. The effects such as the improvement of sex are extremely remarkable.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of the repair method of the present invention, FIG. 2 is a perspective view showing a state of being applied to a damaged portion of a steel tubular polyolefin anticorrosion coated steel material, and FIG. 3 is a steel sheet pile-shaped polyolefin anticorrosion coated steel material. It is a perspective view showing the state applied to the damaged part. 1 ... Steel material, 2 ... Polyolefin anticorrosion coating layer, 3 ...
Damaged part, 4 …… Zinc sheet as metal piece, 5 …… Filler, 6 …… Repair sheet

Claims (3)

[Claims] 1. In repairing a damaged portion of a steel material anticorrosively coated with polyolefin up to the steel surface, a metal piece having a base electric potential with respect to iron is first installed on the damaged steel surface. A method for repairing a damaged portion of a steel anticorrosion coating layer, which comprises filling a filler on the top and further spreading a repair sheet thereon. 2. A metal piece having a base electric potential with respect to iron is arranged at the boundary between the damaged steel surface and the anticorrosion coating layer, and a filler is bonded to the steel surface at the center of the damaged steel surface. The method for repairing a damaged portion of a steel anticorrosion coating layer according to claim (1), wherein there is room to do so. 3. A metal piece having a base electric potential with respect to iron and having a width of 1 mm or more and less than 1/3 of the size of a damaged portion, a thickness of 50 to 1000 μm.
The method for repairing a damaged portion of a steel material anticorrosion coating layer according to claim 1, which has a sheet shape or a linear shape.