JPS5914126B2 - Corrosion prevention method for steel pipe piles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing corrosion of steel pipe piles that are supporting structures of piers, dolphins, etc.

Steel pipe piles constructed under the sea are reliably protected from corrosion in the submerged portions below the sea level using cathodic protection methods, but it is difficult to prevent corrosion in the splash zones and ebb and flow areas.

Conventionally, various methods have been used to prevent corrosion of such parts of existing steel pipe piles, such as painting with anti-rust paint, covering with mortar, and wrapping with anti-corrosion petrolatum tape. However, when coating with paint, it is important to apply sufficient pre-treatment on land before applying a high-quality coating, but if there is a portion of the coating that remains due to a pile driving error, it may be difficult to apply coating.V) Existing steel pipe piles When painting the ebb and flow areas where corrosion is particularly severe, it is important to
Due to the influence of waves, etc., it is extremely difficult to carry out sufficient pretreatment and painting; however, defects such as poor adhesion are likely to occur, making it impossible to achieve a sufficient desired corrosion protection effect. In addition, mortar coating is especially important for existing steel pipe piles.
Due to the severe unevenness of the surface of the corroded part, it is difficult to completely seal the lower part of the mortar layer (10), which is likely to cause defects (10), and the installation of the formwork can be seriously damaged due to the excessive force, especially of existing steel pipes. The disadvantage of using piles was that they required not only formwork but also scaffolding for pouring mortar, making construction costs extremely high. Furthermore, covering with petrolatum-based anticorrosive tape has drawbacks such as it is difficult to wrap it tightly under water15, and exposed parts of the petrolatum are washed away by waves, and the covering slips and falls off. It was also not desirable. This invention aims to provide a corrosion protection method for steel pipe piles that is relatively easy to construct even for existing steel pipe piles, has an excellent corrosion protection effect, and has excellent durability. .

That is, this invention applies a water-repellent, water-displacing anti-corrosion oil that can be applied underwater to the outer circumferential surface of the splash zone and ebb and flow portion of a steel pipe pile, and also applies a corrosion-proof cover that can be closely attached to the outer circumference of the steel pipe pile. After forming a swelling adhesive layer on the inner peripheral surface of the steel pipe pile that absorbs the rust preventive oil and swells to exhibit an adhesive effect, the anticorrosion cover is tightly attached to the outer peripheral surface of the steel pipe pile coated with the rust preventive oil. It is characterized by being coated with. 30 This will be further explained with reference to the illustrated embodiment as follows.

First, the outer circumferential surface of a steel pipe pile 1 such as a pier constructed by submerging the lower part below the sea surface L, especially the outer circumferential surface of the splash zone and ebb and flow area as shown in FIG. 1, is cleaned in advance. After that, a water-repellent, water-displacing rust preventive oil 2 that can be applied underwater is applied.

This coating may be done by hand coating, for example, while wearing gloves, and the coating thickness is 10 to 10.
0μ is fine.

The water-displacing antirust oil 2 used for this purpose includes petrolatum, liquid paraffin, petrolatum, low polymerization degree polyethylene, polypropylene, paraffin type, naphthene type,
The main component is aromatic oil, etc., and as a water-displacement anti-rust additive, petrolatum, liquid paraffin, vaseline, normal paraffin, isomeric paraffin, low- and high-polymerization polyethylene, polypropylene, and other polyolefins, or oxides obtained by oxidizing copolymers thereof with air or oxygen, or metal salts thereof, such as lithium, sodium, potassium, magnesium, calcium, strontium, barium, aluminum, iron, cobalt, nickel, Formulations with the addition of one or more zinc and the like are used. In addition, general anti-corrosion pigments such as zinc dust, iron oxide, and gamma hematite may be added as pigments, and water absorbing agents such as Bortland Moment, anhydrous gypsum, and quicklime may also be added. There is also. Typical formulation examples of such water-displacing rust preventive oils are shown below.

On the other hand, a corrosion-proofing cover 3 is prepared which can densely cover the outer peripheral surface of the steel pipe pile 1 over a required range.

The anti-corrosion cover 3 may have any configuration as long as it can be tightly and tightly attached to the outer peripheral surface of the steel pipe pile 1.
Generally, as shown in FIG. 2, a plurality of members 3a, 3b having an arcuate cross section are used, their circumferential ends abutted against each other, and outer bent edge 4
, 4 are fastened with bolts and nuts 5 to form a circular cross section. Of course, other than this, it is also possible to form a cylindrical shape as a whole by sequentially fitting, bolting, etc., a number of pieces divided in the circumferential direction and connecting them with an arcuate cross section; It may also be a sheet that can be wrapped around a steel pipe pile. In any case, this anti-corrosion cover 3 is in the attached state.
It is preferable that the material be made of elastic material such as vulcanized rubber or stretchable synthetic resin. Of course, the material must be as excellent as possible in oil resistance, seawater resistance, weather resistance, etc. In response to such requests, specifically, the materials for the anti-corrosion sheet 3 are as follows:
Examples of suitable materials include polychloroprene, chlorosulfonated polyethylene, chlorinated polyethylene, epichlorohydrin rubber or copolymer rubber, medium-soft polyvinyl chloride, polyvinylidene chloride, silicone rubber, fluororubber, polyurethane, and elastic epoxy resin. be able to. Furthermore, instead of making the entire structure from the same material, the surface directly exposed to the outside and the surface that comes into contact with the antirust oil may be constructed from a combination of different materials suitable for each. For example, for the outer layer, butyl rubber, which has poor oil resistance but excellent other properties, or olefin rubber such as ethylene-propylene terpolymer is used alone or in a blend, and for the inner layer, nitrile rubber, which has excellent oil resistance, is used. Rubber or the various materials listed above may be used alone or in a blend. Note that various antifouling agents may be added to this cover to prevent attachment of marine organisms. The anti-corrosion cover 3 is coated with a swelling adhesive layer 6 which absorbs the anti-rust oil and swells to produce an adhesive effect on the inner peripheral surface of the anti-corrosion cover 3.

The use of this swelling adhesive is a major component of this invention.1 Its main components include, for example, butyl rubber, ethylene/propylene terpolymer, natural rubber, isoprene, butadiene rubber, isobutylene, styrene/butadiene. Groups such as copolymers, ethylene/cyclopentadiene copolymers, styrene/butadiene rubber, styrene/butylene copolymers, or asphalt, isoparaffin, petroleum resins, amorphous, polyethylene, long oil alkyd resins, petrolatum, rosin, rosin Derivatives, coumaron/indene resin, xylene resin, toluene resin, phenol resin, etc. are used. In addition to one or more of these, anti-rust pigments such as those listed as additives for anti-rust oil, fillers such as barite, calcium carbonate, clay, diatomaceous earth, silica, zeolite, reinforcing agents such as zinc white, carbon, etc. In addition, general anti-aging agents, vulcanizing agents, vulcanization accelerators, plasticizers, etc. may be added as necessary. A specific formulation example of this swelling type adhesive is as follows. Next, the anti-corrosion cover 3 with the swelling adhesive layer 6 formed on the inner circumferential surface as described above is tightly attached to the outer circumferential surface of the portion of the steel pipe pile 1 coated with anti-rust oil as shown in FIG. do.

As a result, as shown in FIG. 1, the swelling adhesive layer 6 comes into contact with the anticorrosion oil 2, absorbs it, swells, and exhibits the desired adhesive effect, so that the anticorrosion cover 3 becomes the sixth layer. As shown in the figure, the adhesive layer 7 has become more layered due to the absorption of rust preventive oil 2 over time.
It is firmly bonded and integrally fixed to the outer surface of the steel pipe pile 1 through the.
Until this complete adhesive fixation is achieved, the anti-corrosion cover 3 must be fitted with bolts to prevent it from shifting after being covered.
It is desirable to use auxiliary support means or fastening means other than the nut 5 for temporary fixation. This temporary fixation is
For example, the anti-corrosion cover 3 may be suspended by a hanging rope,
A magnet may be placed on the outer surface of the cover 3 and the cover 3 may be fixed using its magnetic adsorption force, or furthermore, a rod or temporary may be placed on the outer surface of the cover and secured from the outside with wire, rope, etc. good. Note that 8 shown in FIGS. 2 and 5 is a sealing material that is interposed between the outer bent edges 4, 4 of the anticorrosive cover 3, if necessary. Next, examples of this invention will be shown.

Example 1 The outer surface of an existing steel pipe pile was rubbed with a wire brush to remove most of the attached organisms and rust, and then the water-displacing rust preventive oil shown in Formulation Example 1 was applied to the splash zone and ebb and flow area. It was applied by hand coating D operation.

On the other hand, the main material is neoprene, which is mixed with carbon black, hard clay, light process oil, etc. and vulcanized (
160℃ x 30 minutes), specific gravity 1.52, hardness (Shor-A) 70 minutes, tensile strength 98 kg/(: m1 elongation 320
0/) was prepared, and the swelling type adhesive layer shown in Formulation Example C was applied and formed on the inner surface of the cover to a thickness of 2.0 ml. Next, this anti-corrosion cover was tightly covered and attached to the outer surface of the steel pipe pile, and it was secured around it with a wire rope, and after 48 hours had elapsed, the securing was released. This allowed the anti-corrosion cover to be completely integrated into the outer surface of the steel pipe pile.
After one year of investigation, it was found that there was no rust on the steel pipe piles at all in the areas where the anti-corrosion cover had been applied, and the anti-corrosion cover remained firmly fixed. . Example 2 As a water-displacing rust preventive oil, the one in Formulation Example 2 was used,
The anticorrosion cover was attached to a steel pipe pile in substantially the same manner as in Example 1, except that the swelling adhesive of Formulation Example A was used.

When examined after one year, it was confirmed that it had the same excellent anticorrosion effect as Example 1.

Example 3 As a water displacement type rust preventive oil, the one in Formulation Example 3 was used,
The anti-corrosion cover was attached in the same manner as in Example 1, except that the swelling adhesive of Formulation Example B was used.

As a result, the same effects as in Example 1 could be achieved. As explained above, this invention applies a water-displacing anti-rust oil to the outer surface of a steel pipe pile, and forms a swelling adhesive layer on the inner surface that absorbs the anti-rust oil and exhibits an adhesive effect. Since the anti-corrosion cover is attached and the cover is fixed with adhesive, it is easy to install even underwater, is suitable for anti-corrosion work on existing steel pipe piles, and has good workability.

In addition, since anti-corrosion oil is used as a base coat, it can be applied without completely cleaning the steel pipe pile, and it provides excellent anti-corrosion effects.In addition, the anti-rust oil is absorbed by the swelling adhesive. Since it is sulfurized, excellent durability is obtained and there is no risk of the anti-corrosion cover falling off. In addition, since the anti-corrosion cover is held by adhesive means and there is no need to use any metal members for this purpose, there is no need to worry about their corrosion, and it can be used in combination with cathodic protection. In addition, unlike cement mortar coating, it does not require large-scale formwork, scaffolding, or other equipment on site, and can be constructed at low cost and in a short period of time. Moreover, it can achieve better corrosion prevention effects than conventional corrosion prevention methods. Has a remarkable effect.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; Fig. 1 is a front view of a steel pipe pile coated with anti-rust oil, and Fig. 2 is a perspective view of a steel pipe pile with a swelling adhesive layer formed on the inner surface of the anti-corrosion cover. Fig. 3 is a front view with the anti-corrosion cover attached, Fig. 4 is a partial longitudinal sectional view of the anti-corrosion cover immediately after it has been installed, and Figs. 5 and 6 are after the anti-corrosion cover has been bonded. They are a partial vertical cross-sectional view and a cross-sectional view of the state. DESCRIPTION OF SYMBOLS 1...Steel pipe pile, 2...Water displacement type rust preventive oil, 3...Corrosion protection cover 6...Swelling type adhesive layer, 7... ···glue.

Claims (1)

[Scope of Claims] 1. A water-repellent, water-displacing anti-corrosion oil that can be applied underwater is applied to the outer peripheral surface of the splash zone and ebb and flow portion of the steel pipe pile, and a corrosion-proof cover that can be closely attached to the outer periphery of the steel pipe pile is provided. After forming a swelling adhesive layer on the inner circumferential surface that absorbs the rust preventive oil and swells to exhibit an adhesive effect, the anticorrosive cover is tightly placed on the outer circumferential surface of the steel pipe pile coated with the rust preventive oil. A method for preventing corrosion of steel pipe piles, characterized by coating them. 2. The method for preventing corrosion of steel pipe piles according to claim 1, wherein the anti-corrosion cover is made of an elastic material such as vulcanized rubber or synthetic resin.