JPS6111776B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for efficiently and completely preventing corrosion of cheese used in piping construction.

Conventionally, when a branch pipe is brought out from the main pipe during piping construction, a T-shaped pipe is formed by welding two straight pipes into a T-shape, as shown in schematic front views in Figures 1 and 2. (Fig. 1) and cheese (Fig. 2) are used.

When connecting a branch pipe to a main pipe by welding using a T-shaped pipe that is a combination of straight pipes as described above, the welded part between the T-shaped pipe and the main pipe and branch pipe is In order to prevent corrosion of the T-shaped pipe, the main body of the T-shaped pipe should be sufficiently coated with anti-corrosion coating at the factory, except for the vicinity of the welded part between the main pipe and the branch pipe. Therefore, at the piping construction site, only the welded ends of the T-shaped pipe with the main pipe and the branch pipe need to be coated with anti-corrosion coating, so the anti-corrosion work is easy.

On the other hand, it does not have a straight pipe part and is small in shape.
Moreover, when constructing piping using a cheese whose welds between the main pipe and branch pipes are close to each other and where the vicinity of the weld has a curved surface, it is necessary to It is impossible to apply anti-corrosion coating at the factory, so after piping construction, it is necessary to apply anti-corrosion coating to the cheese, including the welded parts of the main pipe and branch pipes to the cheese, on site. I don't get it.

Conventionally, known on-site corrosion prevention methods for such piping after construction include wrapping asphalt slate, wrapping anticorrosion sheets and anticorrosion tape, and so on.

Although the above method is suitable for piping construction using asphalt cladding, it cannot necessarily be said to be a suitable corrosion prevention method for piping construction using plastic cladding due to problems such as volume resistivity.

The above-mentioned method is a corrosion-preventing method that is currently generally applied to plastic cladding tubes, and FIGS. 3 and 4 show the anti-corrosion coating mode of the method in a schematic longitudinal sectional view and a front view. As shown in the figure, the method involves first applying a thin undercoat 4 to the outer surface of the cheese 3 including the welded ends of the main pipe 1 and branch pipes 2, and then cutting the anticorrosion sheet 5 at predetermined locations. The welding area 7 and the cheese 3 are pasted to cover them, and after the anticorrosion sheet is pasted, the anticorrosive tape 6 is wrapped twice in a 1/2 wrap as shown in FIG. 4 to provide an anticorrosive coating. It is being done. In the drawings, numerals 8 and 9 indicate plastic coatings that are previously coated on the main pipe 1 and the branch pipes 2.

However, in the above method, it is difficult to uniformly apply the undercoat 4 and requires skill and time.

When wrapping the anti-corrosion tape 6, it is difficult to cross the neck part, and there is a risk of it rubbing.

As shown in FIG. 4, a triangular portion is formed that cannot be covered with the anticorrosive tape 6.

These problems make it extremely difficult to carry out anti-corrosion construction.

This invention provides an on-site corrosion prevention method for cheese that solves the problems of the conventional corrosion prevention methods as described above. are formed parallel to each other and covered with an adhesive-coated heat-shrinkable plastic sheet formed by branching into two branches with arc-shaped notches at both ends, and rectangular adhesive-coated parts of the main pipe and branch pipes are covered with a heat-shrinkable plastic sheet. To efficiently and completely protect cheese from corrosion with a simple operation by partially wrapping the coating layer of the main pipe and branch pipes and the sheet covering the cheese with a heat-shrinkable plastic sheet coated with an agent. It has the following characteristics.

Next, the present invention will be explained with reference to examples and drawings.

FIG. 5 is a cross-sectional view showing the anticorrosion mode when cheese is anticorrosive according to the present invention.

First, the planar shape as shown in FIG.
An adhesive-applied heat-shrinkable plastic sheet 10, which is formed parallel to each other at the center and branched into two with arc-shaped notches at both ends, is wrapped up to the shoulder of the cheese 3 including the welding location 7. Then the 8th
As shown in the figure, both ends of the sheet 10 are attached to the neck of the cheese, that is, the central part of the riser pipe along the pipe axis direction, and the a-end of the sheet 10 is attached to the main pipe 1 so that the sheet 10 floats. The sheet 10 is pasted in one place, heated with a low-heat burner 13 until it becomes a little soft, and the sheet 10 is wrapped around the riser pipe with some tension to shrink it by heating. Next, the uncoated parts of the main pipe 1 and branch pipes 2 are covered with rectangular adhesive-coated heat-shrinkable plastic sheets 11 and 12 as shown in FIG. It is partially wrapped with the coating layers 8 and 9 of No. 2, wrapped around it, and heated and shrunk.

The dimensions of each part of the adhesive-coated heat-shrinkable plastic sheet 10 covering the cheese 3 are as follows. In other words, the total length A of the central part is the branch pipe 2
The length is the sum of the length from the end of the coating layer 9 around the cheese 3 to the end of the opposing branch pipe coating layer plus the lap margin with the sheet 12, and the width B of the central parallel part is the width B of the sheet covering the cheese 3. 11, and the length C of the center parallel part is the length from the base of the rising pipe of the cheese 3 to the base on the opposite side around the tube circumference, and Width D of arc-shaped part
is the length of the semi-circumference of branch pipe 2 plus the wrap allowance,
The shape of the arc follows the semicircumference of the branch pipe 2.
Further, the length of the side E adjacent to the arcuate portion is the length of the curve of the shoulder of the cheese 3 plus the overlap margin with the sheets 11 and 12, and the length of the side E between C and E The length is the length that covers half of the shoulder of the cheese 3 plus the amount of overlap with the sheet from the opposite side.

On the other hand, the width of the sheets 11 and 12 is the sum of the length of the uncoated part and the wrap length between the coating layers 8 and 9 and the sheet 10, and the width is the length of the main pipe 1 or the branch pipe 2. The length should be the entire circumference with an appropriate lap allowance.

However, the above dimensions are the lengths after shrinkage, and in reality, the lengths obtained by adding the shrinkage allowance to the above dimensions are used.

In addition, in the above example, the corrosion protection aspect of one coating was described, but if necessary, the same operation may be repeated to form a double coating or more laminated coating. A protective sheet may be applied, or mastic tape may be wrapped around the plastic coating of the tube, the laps between the sheets, and the welded areas (beads).

As explained above, according to the anti-corrosion method of the present invention, it is possible to perform anti-corrosive coating treatment with about 1/2 of the labor required by the above-mentioned conventional method, and in about 2/3 of the working time. The next cheese is
This brings about industrially useful effects such as a good insulation resistance value of 10 ¹¹ Ω or more.

[Brief explanation of the drawing]

Fig. 1 is a front view of the T-tube, Fig. 2 is a front view of the cheese, Figs.
The figure is a sectional view showing the anti-corrosion mode when cheese is anti-corrosive according to the present invention, and Figs. 6 and 7 are
FIG. 8 is a plan view of a sheet used for corrosion protection of cheese according to the present invention, and is a schematic perspective view showing the corrosion protection mode. In the drawing, 1...main pipe, 2...branch pipe, 3...cheese, 4...
...Undercoat, 5...Anti-corrosion sheet, 6...Anti-corrosion tape, 7...Welding location, 8, 9...Plastic coating layer, 10, 11, 12... Heat-shrinkable plastic sheet with adhesive, 13... burner.

Claims (1)

[Claims] 1 When constructing the branch pipe 2 to the main pipe 1 using the cheese 3, use a heat-shrinkable plastic pipe with an adhesive, whose central part is parallel and both ends are cut out in an arc shape and branch into two branches. The cheese 3 is covered with a sheet 10, and the uncoated parts of the main pipe 1 and the branch pipes 2 are covered with rectangular sheets 11 and 12 made of adhesive-coated heat-shrinkable plastic. When covering the cheese 3 with the sheet 10, the sheet 10 is heated while being heated until the sheet 10 is softened. The sheet 10 is stretched and wrapped around the riser pipe of the cheese 3, and each part of the sheet 10 has a total length A at the center extending from the end of the coating layer 9 of the branch pipe 2 around the cheese 3 to the opposing branch pipe coating layer. The width B of the central parallel portion covers the cheese 3 and has a length that is the sum of the length reaching the end and the overlap margin with the rectangular sheet 11. and the length C of the central parallel part
has a length from the base of the riser pipe of the cheese 3 to the base on the opposite side around the pipe periphery, and the width D of the arc-shaped part of the branch part at both ends is a wrap width around the semicircumference of the branch pipe 2. The arcuate portion has a length of branch pipe 2
The length of the side E adjacent to the arcuate portion is equal to the length of the shoulder of the cheese 3 plus the overlap with the rectangular sheets 11 and 12. and the length of side F between C and E is
A method for preventing corrosion of cheese in piping construction, characterized by having a length that covers half of the shoulder of the cheese 3 plus a lap allowance with the sheet 10 from the opposite side.