JPH1061834A - Double pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electric corrosion of a pipe, to improve strength, and to improve safety by a method wherein an outer pipe made of fiber-reinforced plastic is formed such that a resin film wound around the outer peripheral surface of an inner pipe made of a steel on the outer periphery of which rust- preventive treatment is applied is interpolated. SOLUTION: The outer peripheral surface of an inner pipe 1 made of a steel is coated with a rust-preventive agent to apply rust-preventive treatment 6. A resin film 2 is wound to form an outer pipe 5 made of fiber-reinforced plastic. The rust-preventive treatment 6 may be treatment wherein a resin film layer is formed and polyethylene terephthalate may be used for the resin film 2. After the resin film is wound around the inner pipe 1 for temporary mounting, fiber-reinforced plastic is sprayed against or applied on the outer peripheral surface of the resin film 2 to form an outer pipe 5. A gap 4 is provided between the wound resin film 2 and the inner pipe 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double pipe through which a liquid such as oil or a gas such as a gas passes.

[0002]

2. Description of the Related Art Conventionally, there has been no double tube, but a single tube made of plated steel or resin coating.

[0003]

When oil pipes, water pipes, gas pipes and the like are buried in the soil, the exposed parts of iron, particularly due to scratches, are liable to be electrically corroded, and this is not a dangerous distribution body. It also causes an accident. It is also very difficult to detect leakage of a distribution body from a pipe buried in the soil.

In view of the above, the present invention can prevent electric corrosion of a pipe, has a high strength, and can secure a space for providing a leak detecting portion when a flowing body such as oil flowing in the pipe leaks. It is intended to provide a double pipe with high safety, for example, it is possible to take measures against leakage.

[0005]

A double pipe according to the present invention comprises an outer pipe made of fiber reinforced plastic with a resin film wound around an outer peripheral surface of a steel inner pipe having an outer periphery subjected to rust prevention treatment. Is formed. Further, a spacer may be provided on the outer peripheral surface of the steel inner tube or on the inner surface of the resin film in contact with the inner tube, or a spacer may be provided between the inner tube and the resin film. .

Further, the spacer may be a projection, a ridge or a line, and in the case of a ridge or a line, the spacer is disposed in the length direction of the tube.

[0007] The present invention having the above-mentioned structure is composed of a double pipe consisting of an inner pipe made of steel and an outer pipe made of fiber-reinforced plastic, so that the safety is higher than that of a single pipe. Because it has high strength and electrical insulation,
And corrosion is also prevented. Further, since the resin film is wound around the outer periphery of the inner tube in contact with the outer periphery of the inner tube, the resin is prevented from adhering to the inner tube when the outer tube is formed, and a gap is formed between the inner tube and the resin film. Will occur. Further, the gap can be reliably generated by the spacer.

[0008] When the inner tube through which the flow body passes is broken by forming the gap, the flow body leaks into the gap between the inner pipe and the resin film, and this gap is used as a detection layer.
Providing the sensing part of the distribution body enables early detection of leakage. By disposing the ridge or linear spacer in the length direction of the pipe, the flow of the leaked liquid is not hindered.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view of the double pipe of the present invention, and FIG. 2 is a vertical side view of the double pipe. And a resin film 2 is wound thereon to form an outer tube 5 made of fiber reinforced plastic.

The rust prevention treatment 6 may be a treatment in which a resin film layer is formed. The resin film 2 may be made of polyethylene terephthalate or the like. The outer tube 5 is formed by spraying or coating on the inner tube 1, and a gap 4 is formed between the wound resin film 2 and the inner tube 1.

FIG. 3 is a front view of another embodiment of the present invention, in which a part of a double tube is cut away. Void 4
Is formed more reliably, the rust prevention treatment 6 on the outer peripheral surface of the inner tube 1 is formed of a resin film layer, and a projection is provided at the same time as the formation of the resin film layer to form a spacer 7.

FIG. 4 shows that the spacer 7 is not a projection, but the inner tube 1.
It is needless to say that the ridges are continuous in the length direction of the inner tube 1 and may be discontinuous ridges. Further, the shape of the spacer 7 may be a triangle, a quadrangle, a semicircle, or any other shape.

FIGS. 5 to 9 show another embodiment in which a spacer 3 is provided on one side of the resin film 2 which is in contact with the outer peripheral surface of the inner tube 1. Spacer 3
Is similar to the case where the spacer 7 is provided on the inner tube 1.

FIGS. 10 and 11 show another embodiment in which the spacer 8 is disposed as an independent member between the inner tube 1 and the resin film 2. As an example, a linear spacer 8 is shown. Is applied to the inner tube 1 and the resin film 2 is wound to form the outer tube 5. Spacer 8
Is not limited to the shape shown in the drawing.

[0015]

According to the present invention, since the double pipe is used, the safety is high, and since the outer pipe is made of fiber reinforced plastic, the strength and insulation are high, and corrosion is prevented. Durable even when buried and used. In addition, a gap is generated due to the interposition of the resin film provided between the inner pipe and the outer pipe, and a more reliable gap is generated by installing a spacer,
If there is a leak from the inner tube, the flow body flows into the gap, so the gap can be used as a detection layer, and if a sensing unit is provided, early detection of the leak is possible, and accidents can be prevented beforehand. It is a high and useful double tube.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a double pipe according to an embodiment of the present invention.

FIG. 2 is a sectional view of the double pipe of FIG. 1;

FIG. 3 is a partially cutaway front view of a double pipe showing another embodiment.

FIG. 4 is a front view of the inner tube showing another form of the spacer of FIG. 3;

FIG. 5 is a partially cutaway front view of a double pipe showing another embodiment.

FIG. 6 is a sectional view of the double pipe of FIG. 5;

FIG. 7 is a partial perspective view of a resin film provided with a spacer of FIG. 5;

FIG. 8 is a partial perspective view of a resin film provided with another spacer of FIG. 5;

FIG. 9 is a partial perspective view of a resin film provided with another spacer of FIG. 5;

FIG. 10 is a cross-sectional view showing another embodiment.

FIG. 11 is a perspective view of the spacer of FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner tube 2 Resin film 3 Spacer 7 Spacer 8 Spacer 4 Void 5 Outer tube 6 Rust prevention treatment

Claims (7)

[Claims] 1. A double tube comprising a fiber reinforced plastic outer tube formed with a resin film wound around an outer peripheral surface of a steel inner tube having an outer periphery subjected to rust prevention treatment. 2. The double pipe according to claim 1, wherein the inner pipe has a spacer protruding from an outer peripheral surface. 3. The double tube according to claim 1, wherein the resin film has a spacer protruding from an inner surface in contact with the inner tube. 4. The double pipe according to claim 1, wherein a spacer is provided between the inner pipe and the resin film. 5. The double pipe according to claim 2, wherein the spacer is a ridge extending in the length direction of the pipe. 6. The spacer according to claim 2, wherein the spacer is a projection.
Double tube as described. 7. The double pipe according to claim 4, wherein the spacer is a linear body extending in the length direction of the pipe.