JPS6246079A - Composite pipe and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application in Industry-■-) The present invention relates to a composite pipe particularly suitable for long-distance transportation of hot water, cold water, other liquids, gases, etc., and a method for manufacturing the same.

(Prior Art and Problems to Be Solved) Pipes for hot water use or for transferring water, other liquids, gases, etc. are often buried directly in the ground at the location where they are used. In particular, pipes that use hot water or refrigerants such as cold water require a sufficient heat insulating layer, but since the heat insulating layer usually does not have sufficient strength against the soil when directly buried, a fairly strong corrosion protection layer is required for the heat insulating layer. , it is necessary to apply a coating layer for external pressure that also serves as waterproofing.

On the other hand, when the distance for transferring hot water, etc. is long, it is necessary to make the continuous length of the pipe as long as possible to reduce the number of intermediate connections, reduce construction costs, prevent corrosion at the joints, and reduce reliability degradation such as leakage. is strongly desired.

Figure 4 is a partial vertical cross-sectional view of an example of a conventional composite pipe used in a series of applications, in which a layer 0211 of cloth tape is wrapped around the outer periphery of a conduit 0D made of hard polyethylene. It is constructed by sequentially applying a reinforcing layer 01, a heat insulating layer CΦ made of hard polyurethane foam, an outer pipe 09 made of a corrugated welded steel pipe, and a corrosion protection layer (If) Gη.

Fig. 5 is a partial vertical cross-sectional view of another example of a conventional composite pipe used for similar purposes. It is constructed by sequentially applying a heat insulation layer 0Φ made of polyurethane foam, an outer pipe 09 made of a welded steel pipe with a corrugated finish, and a corrosion protection layer 09 (+71).

Since the pipe has a corrugated metal outer pipe 051 and a corrosion protection layer (If) (lη), the outer diameter of the pipe is large and the flexibility is poor.Therefore, the length of the pipe must be shortened mainly due to transportation restrictions. Currently, cables are laid while being connected on-site, which inevitably increases construction costs and reduces reliability v1 at the connection.

(Means for Solving the Problems) The present invention provides a composite pipe that solves the above-mentioned problems +, ′, and (), and a method for manufacturing the composite pipe. , is a composite pipe having a corrugated hard polyethylene pipe layer as the outermost layer and a heat insulation layer inside the pipe layer, and its manufacturing method is as follows: At least the outermost corrugated hard polyethylene pipe layer of the composite pipe is laid at the installation site The purpose is to perform extrusion corrugation processing and molding.

(Example)) Figures 1 and 2 are both partial side views showing a -L half vertical section of an example of the composite pipe of the present invention.
1) is the innermost layer of flexible pipe, ■ is the outermost corrugated rigid polyethylene pipe layer, (3) is the inner heat insulation layer, (4
) is a plastic anti-corrosion layer.

The innermost flexible pipe (1) may be a plastic pipe with appropriate strength and flexibility such as a hard polyethylene pipe, cross-linked polyethylene pipe, polybutene pipe, or polypropylene pipe, or an extruded lead pipe, an extruded aluminum pipe, or a lead pipe. Metal pipes such as m-joint pipes made of extruded aluminum pipes and corrugated welded stainless steel pipes are used for the pipes. In the case of metal pipes, as shown in Figure 2, a plastic anti-corrosion layer (44 mm) made of polyethylene, polyvinyl chloride, etc.
) is preferable, and it is of course possible to apply corrugated pressure to metal pipes other than corrugated welded stainless steel pipes.

The outermost layer is a conventional corrugated metal tube +151 and anti-corrosion layer 661
Instead of 0η, a corrugated hard polyethylene pipe (2) with excellent compressive strength and tensile strength is provided, and a heat insulating layer of foamed polyethylene, foamed polyurethane, glass wool, etc. is provided inside the pipe.

The composite pipe of the present invention described above has a smaller outer diameter than conventional products and has appropriate flexibility, so it can be transported by winding it in a drum for 100 to 200 meters. A manufacturing method like this is used.

That is, the manufacture of the innermost layer flexible pipe 0) and its outer periphery -
The heat insulation layer (3) of 1- is molded using special equipment at the factory.
Rather than increasing the diameter, it is rolled up into a drum to take advantage of its flexibility and transported in a long length to the installation site. Then, at the site, while inserting the pipe, a hard polyethylene pipe is extruded using an extruder, and a corrugated process is performed using a corrugating machine to form a corrugated hard polyethylene pipe layer (2). At this time, since there are no restrictions on transport at the site, it becomes possible to use ultra-large drums, and it is possible to manufacture large diameter pipes while keeping them long.

It is also desirable to form the heat insulating layer (3) on-site by extrusion and foaming, but this is currently difficult as it requires large equipment and involves advanced processing technology. Therefore, a cylindrical foamed plastic body is manufactured in advance at a factory, cut vertically in one or two places as shown in Figure 3 (a) and (b), and coated on the inner pipe on site. Then wrap binder cloth tape or plastic over it to fix it. Thereafter, a corrugated hard polyethylene pipe layer may be formed on the -L by the same method as described above.

It should be noted that a new extruder and corrugating machine are not required to accomplish the above method; for example, if the product can be loaded onto a low-floor trailer, it can be transported in a container.

If the corrugated hard polyethylene pipe layer is formed on-site using the first manufacturing method, the drum will normally produce 200 to 400
00 m If a heat insulating layer is also formed on site at the same time using the first and second manufacturing method, lengthening of 500 to 1000 m can be realized. Therefore, it is particularly advantageous for geothermal utilization, factory pipes, road heating pipes, gas pipes, etc. where several dozen pipes are laid. In addition, even in the case of conduit-like installation or common ditch installation in urban areas, rather than direct burial, it becomes possible to install long lengths within a limited time, and the number of connection points is reduced, so the space required for this purpose is also reduced. I can do it.

(Effects of the Invention) According to the above-described composite pipe of the present invention, the outer diameter is smaller than that of conventional products and has appropriate flexibility, making it possible to transport long objects.

Further, according to the manufacturing method of the present invention, when the corrugated rigid polyethylene pipe layer or the layer and the heat insulating layer inside the pipe layer are formed on site, it becomes possible to transport the pipe over a longer length. As a result, the number of connections is reduced, significantly reducing installation time and increasing the reliability of the pipe.

[Brief explanation of the drawing]

Fig. 1 and Fig. 2 are both partial side views of an embodiment of the composite pipe of the present invention, with a half longitudinal cross-section taken at -, and Figs. A cross-sectional view is shown. - Figures 4 and 5 both show partial longitudinal cross-sectional views of conventional composite pipes. DESCRIPTION OF SYMBOLS 1...Flexible pipe, 2...Corrugated hard polyethylene pipe layer, 3...Heat insulation layer, 4...Anti-corrosion layer.

Claims (5)

[Claims] (1) A composite pipe comprising a flexible pipe as the innermost layer, a corrugated hard polyethylene pipe layer as the outermost layer, and a heat-retaining layer inside the pipe layer. (2) The composite pipe according to claim 1, wherein the innermost flexible pipe is a plastic pipe. (3) The composite pipe according to claim 1, wherein the innermost flexible pipe is a metal pipe and has a plastic anticorrosive layer on its outer periphery. (4) At least the outermost corrugated hard polyethylene pipe layer of a composite pipe consisting of a flexible pipe as the innermost layer, a corrugated hard polyethylene pipe layer as the outermost layer, and a heat insulation layer inside the pipe layer is installed at the site. A method for manufacturing a composite pipe, characterized in that the composite pipe is formed by extrusion corrugation processing. (5) The method for manufacturing a composite pipe according to claim 4, characterized in that the outermost corrugated hard polyethylene pipe layer and the inner heat-insulating layer are formed at the installation site.