JPH07107440B2 - Anticorrosion method for pipe connection - Google Patents

Description

The present invention relates to an anticorrosion method for pipe joints that connect pipes.

[Prior art]

In order to cover the pipe connection part in a watertight manner, for example,
A cover for a pipe joint as described in Japanese Patent Laid-Open No. 54-92430 is known. According to the invention described in the publication, recesses conforming to the shape of a pipe joint are symmetrically provided on the inner surface of a sheet formed in a folding type, and an adhesive is applied to the entire inner surface.

[Problems to be Solved by the Invention]

Since the conventional anticorrosion cover is coated with an adhesive on the entire inner surface, a part of the fitting will stick to the adhesive when it is attached to the fitting, and if it is released for correction, it will form. The sheet is deformed and the workability is poor, and it is difficult to install the sheet at a predetermined position. As a result, the watertightness is incomplete and there is a problem in the reliability of the anticorrosion effect.

[Means for Solving the Problems]

The anticorrosion method of the pipe connecting portion of the present invention is made to solve the above problems, and the gist thereof is to connect the pipe connecting portion with an anticorrosive cover having an adhesive layer formed on the inner surface thereof. In the anticorrosion method, the anticorrosion method for a pipe connecting portion is characterized in that an anticorrosion cover is applied to at least one of the pressure-sensitive adhesive layer surface of the anticorrosive cover and the surface of the pipe connecting portion to cover the anticorrosive cover on the pipe connecting portion. Exist in.

The cover body used in the present invention is shaped so as to cover the pipe connection portion, and is made of a thermoplastic resin such as polyvinyl chloride, polyethylene, polypropylene, ABS or the like, or a resin in which these resins are foamed, or glass fiber reinforced. Those made of synthetic resin such as polyester are preferable.

Further, even if the cover body is composed of a plurality of divided pieces, one side edge of the plurality of divided pieces is continuous, and the cover can be split at the continuous portion. Good.

As the pressure-sensitive adhesive layer, a rubber-based pressure-sensitive adhesive whose main component is synthetic rubber such as butyl rubber or natural rubber, or a pressure-sensitive adhesive whose main component is petrolatum-based rust preventive grease is used. It is preferable to provide release paper on the surface of the pressure-sensitive adhesive layer in order to prevent dust or the like from adhering to the surface of the pressure-sensitive adhesive layer or unnecessary adhesion to other substances.

Adhesion suppressive substances are substances that temporarily suppress the adhesive strength of the adhesive layer of the anticorrosion cover, do not show strong adhesiveness when the adhesive layer touches the surface of the pipe connection, and then recover the adhesive strength again. Say.

Examples of such adhesion-suppressing substances include methylal coke,
Alcohols such as ethyl alcohol, glycols such as ethylene glycol and propylene glycol, rust preventive oil,
Tannic acid aqueous solution, etc., especially ethylene glycol,
A tannic acid aqueous solution having a concentration of 0.3 to 1% is preferable. When this adhesion-suppressing substance is applied thickly to the surface of the adhesive layer or the surface of the pipe connection part, when the adhesive layer is pressed against the surface of the pipe connection part, for example, it suppresses the adhesion to the adhesive surface of the mating surface of the anticorrosion cover or the pipe surface of the joint part. Material is extruded, which is not preferable. Also, if the coating film of the adhesion-suppressing substance is thick, the reproducibility of the adhesion will be poor, so it is preferable to apply it as thinly as possible. For this reason, it is preferable that the viscosity of the adhesion-suppressing substance be 100 cps (20 ° C) or less and that excess coating liquid be immediately drained off. In addition, it is better to use such a low viscosity for brush coating and spray coating. Good sex.

When alcohols, glycols, and rust preventive oils are used as the adhesion-suppressing substance, they have compatibility with the above-mentioned pressure-sensitive adhesive, so if the pressure-sensitive adhesive phase coated with the substance is pressure-contacted to the surface of the pipe connecting portion. The substance gradually migrates into the pressure-sensitive adhesive, the tack-suppressing action disappears, the tackiness is reproduced, and the anticorrosion cover completely adheres to the pipe connection portion with time. Further, when an aqueous tannic acid solution is used as the substance, the adhesiveness is suppressed in the initial stage due to the presence of water of the aqueous solution on the adhesive layer surface or the surface of the pipe joint, and at the same time, tannic acid is the iron surface of the pipe connecting portion. A film of iron tannate is formed on to prevent the occurrence of corrosion. In addition, the water content that had suppressed the tackiness at the beginning of the coating gradually evaporates to the space between the anticorrosion cover and the pipe joint part, assisting the action of earth pressure, and the adhesive force is reproduced and the anticorrosion property is accompanied. The cover and the tube connection part will come into close contact with each other over time. The water vaporized into the space between the anticorrosion cover and the pipe joint portion does not re-enter the pressure-sensitive adhesive layer surface, and reliable watertightness can be obtained for a long period of time.

The above-mentioned adhesion-suppressing substance is applied to either the adhesive layer surface or the surface of the pipe connection portion during construction, or both.
When applied to the adhesive layer surface, it is easy to contact the entire surface, and when applied to the surface of the pipe connection part, it is easy to contact the adhesive layer of the anticorrosion cover such as the end of the flange or the bolts and nuts that fix the flange. It is effective to apply it to the convex portion.

Further, the application of the adhesion-suppressing substance may be performed by brush coating or spray coating.

It should be noted that if the adhesion-suppressing substance is not applied to the adhesive layer surface of the pipe to be joined to the pipe and the anticorrosion cover of the anticorrosion cover that is directly coated on the pipe, the anticorrosion cover and the pipe surface will adhere to each other with a strong adhesive force from the beginning. It is preferable in terms of anticorrosion effect by preventing intrusion of water from the outside.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 3, a is a pipe joint, and flanges 1 and 1'welded to one end of steel pipes 2 and 2'are bolts and nuts 3 and 3 ', respectively.
They are joined with ... Reference numeral 4 denotes a coating portion in which a 1% tannic acid aqueous solution is coated by brush onto the peripheral portions of the iron flanges 1, 1'and the bolts and nuts 3, 3, ... Second
FIG. 5 shows an anticorrosion cover. The anticorrosion cover 5 is composed of two symmetrically divided pieces 5a and 5b, and each of the divided pieces 5a and 5b has a shape that substantially matches the outer diameter of the pipe joint. A cover body 51, 51 for covering the pipe body, and pipe covering portions 52, 52 extending outward from both ends of the cover body 51, 51 and having a shape along the outer shape of the steel pipe connected to the pipe joint, and the cover body. Fitting portions 53, 53 are formed at both end edges from 51, 51 to the pipe covering portions 52, 52.

A pressure-sensitive adhesive layer 6 made of a pressure-sensitive adhesive containing unvulcanized butyl rubber as a main component is provided on the entire inner surfaces of the divided pieces 5a and 5b with a substantially uniform thickness. Reference numeral 54 denotes a band insertion hole for covering the steel pipes 2, 2'with the pipe covering portions 52, 52 and then tightening the pipe covering portion 52 from the outer surface thereof.

The anticorrosion cover 5 thus formed is applied to the pipe joint a and the steel pipes 2 and 2'on both sides thereof in FIG. 3 while the tannic acid aqueous solution is undried, and the mating portions 53 and 53 are mated to form the band insertion hole 54. A band (not shown) was inserted through and tightened and fixed. FIG. 1 is a cross-sectional view showing a state in which the pipe joint a and the steel pipes 2, 2 ′ are covered with the anticorrosion cover 5. When the pipe joint a is covered with the anticorrosion cover, since the surface of the pipe joint a is coated with the tannic acid aqueous solution, the adhesive 6 on the inner surface of the cover body 51 is attached to the peripheral portions of the flanges 1 and 1'of the pipe joint a and the bolts. Even if the nut 3 was touched, it did not stick, and the device could be installed very easily. After 20 days of burying this in the soil, the anticorrosion cover was cut open, and the state of adhesion between the anticorrosion cover and the iron flange was observed.As a result, a black coating of iron tannate was formed on the part of the iron flange where the tannic acid aqueous solution was applied. But no corrosion occurs,
The outer peripheral surface of the iron flange was completely adhered to the adhesive, and the portion where the bolt / nut coated with the aqueous tannic acid solution was in contact with the adhesive was also well adhered.

Similar results were obtained even when the tannic acid aqueous solution was not applied to the pipe joint side but only the adhesive of the anticorrosion cover was applied.

〔The invention's effect〕

According to the present invention, since it has the above-mentioned configuration, the following operational effects are obtained.

At least one of the pressure-sensitive adhesive layer surface of the anticorrosion cover or the surface of the pipe connection part is coated with an adhesion-suppressing substance, so that the adhesive layer on the inner surface of the anticorrosion cover does not adhere to the pipe joint when the pipe connection part is covered with the anticorrosion cover. Therefore, it is extremely easy to correct the positional deviation of the anticorrosion cover, and the anticorrosion cover can be mounted at a correct position with good workability without being deformed, and a reliable anticorrosion effect can be obtained.

After coating the anticorrosion cover, the adhesive strength of the pressure-sensitive adhesive surface recovers with time, and the surface of the pipe connection portion and the anticorrosion cover are completely adhered to each other, so that perfect watertightness can be obtained.

According to the present invention, the work is extremely simple because the adhesion-suppressing substance is only applied to at least one of the surface of the pipe connection portion and the surface of the pressure-sensitive adhesive layer on the inner surface of the anticorrosion cover.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an embodiment of a pipe connecting portion according to the anticorrosion method of the present invention, FIG. 2 is a perspective view showing an example of an anticorrosion cover used in the anticorrosion method of the present invention, and FIG. 3 is of the present invention. It is a perspective view of a pipe connection part before covering a corrosion protection cover in a corrosion protection method. a: pipe connection part, 4: application part of anti-adhesion substance, 5: anticorrosion cover, 51: anticorrosion cover body, 6: adhesive layer.

Claims (1)

[Claims] 1. A method for anticorrosion of a pipe connecting portion, wherein a pipe connecting portion is covered with an anticorrosive cover having an adhesive layer formed on the inner surface thereof, and an adhesive is applied to at least one of the adhesive layer surface of the anticorrosive cover and the surface of the pipe connecting portion. An anticorrosion method for a pipe connecting portion, which comprises applying an inhibitor to cover the pipe connecting portion with an anticorrosion cover.