JP2002349771A - Flexible fluid transport tube and method of heating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the electric resistance of a reinforcing layer, and to apply a current to the reinforcing layer to heat a flexible fluid transport tube so that a curl wound around a drum can be removed. SOLUTION: A rubberized cloth tape or the like is wound around an inner tube 1 made of plastic to form a cushion layer 2, and a reinforcing layer 3 is further provided thereon by spirally winding a metal tape into a plurality of layers. The mechanical strength is increased while maintaining the flexibility of the inner tube 1 so that the inner tube 1 can withstand a middle or high pressure. Further, on the reinforcing layer 3, a pressing tape layer 4 is provided by winding a rubberized cloth tape or the like, and a protective layer 5 provided by extrusion-coating plastic is provided thereon. In such a flexible fluid transport pipe, an insulating layer 4 is provided between the reinforcing layers 3 and 5 provided in a plurality of layers to reduce the cross-sectional area of each layer and increase the electric resistance. Then, the flexible fluid transport pipe is heated by energizing one of the layers or a plurality of layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible fluid transport pipe that can be used even in a medium or high pressure range, and a heating method for removing the flexible fluid transport pipe.

[0002]

2. Description of the Related Art Conventionally, materials for gas pipes disposed in a tunnel, underground, on the sea floor, and the like have been regulated by law according to the internal pressure used. In other words, plastic pipes can be used together with steel pipes and cast iron pipes in the low pressure range of 0.1Mpa or less, but plastic pipes with poor pressure resistance cannot be used in medium and high pressure ranges above 0.1Mpa, limited to cast iron pipes or steel pipes. I was

[0003] Cast iron pipes and steel pipes are inflexible and have problems in production and transportation. When the pipes are cut into short pipes one by one and laid, a large number of them are connected. The required length of the pipeline was formed. As described above, in the case of a gas pipe made of a cast iron pipe or a steel pipe, a large number of pipes must be connected when the pipe is laid, so that the work load at the time of laying has been increased.

On the other hand, recently, as a part of deregulation, there has been no regulation on materials according to internal pressure used, and plastic pipes can be used as gas pipes even in middle and high pressure regions. Since the plastic tube is flexible and can be wound on a drum immediately after the production, it can be produced and transported in units of several hundred meters continuously. Therefore, if a plastic pipe is used as the gas pipe, the connection work at the time of laying can be greatly reduced. However, plastic pipes have low mechanical strength and cannot be used in medium and high pressure regions as they are.

Therefore, the applicant of the present application has previously filed Japanese Patent Application No. 2000-335.
As 314, an inner tube made of plastic, a reinforcing layer formed by spirally winding a metal tape on the outer side of the inner tube, and a protective layer provided by coating the entire outer side of the reinforcing layer with plastic can be provided. A flexible composite gas tube was proposed. The metal tape of the reinforcing layer should improve the flexibility of the gas pipe, reduce the unevenness of the pipe surface, and reduce the friction resistance when laying,
In order to improve the workability at the time of manufacturing, etc., spiral winding was performed in a plurality of layers. Then, the thickness of the entire reinforcing layer is determined so as to have sufficient strength according to the internal pressure applied to the pipe, the inner diameter of the pipe, and the like, and the thickness of each metal tape is determined by equally dividing the thickness.

[0006] By doing so, the mechanical strength is enhanced while maintaining the flexibility of the plastic tube, and a sufficient pressure resistance against the internal pressure can be maintained. As a result, the plastic pipe can be used as a gas pipe in the middle and high pressure regions, and the connection work is greatly reduced when the pipe is laid, thereby improving workability.

[0007] The flexible composite gas pipe can be manufactured continuously in units of several hundreds of meters, and immediately after being manufactured, it is wound up on a drum and transported. In that way, it is manufactured continuously and long,
Because of transport, connection work during installation can be greatly reduced.

When such a gas pipe is wound around a drum and transported, the gas pipe has a curl. Therefore, it is necessary to remove the curl when laying the gas pipe. As a method of removing the curl of the plastic tube wound on the drum as described above, a ribbon heater is wound around the outer periphery of the tube and heated to soften the plastic, remove the curl of the tube, and perform straightening. Was common.

[0009]

However, in such a method of heating by winding the ribbon heater, there is a problem that it takes time and effort to wind the ribbon heater. Therefore, it was considered that an electric current was applied to the reinforcing layer and heating was performed using Joule heat. By doing so, the trouble of winding the ribbon heater can be omitted.

However, the thickness of the reinforcing layer is determined so as to have sufficient strength in accordance with the internal pressure applied to the pipe, the inner diameter of the pipe, and the like. However, when the internal pressure is high, the thickness of the reinforcing layer becomes large. Since the electric resistance is reduced, a large amount of heat cannot be obtained even when a large current flows. Therefore, in order to remove the curl and obtain the heat generation required for performing the straightening, it is necessary to supply a huge current of several hundreds of amps, and there is a problem that a power supply that can withstand the current cannot be prepared.

The present invention solves such a problem, and can increase the electric resistance of the reinforcing layer while maintaining the strength of the reinforcing layer sufficient for the internal pressure applied to the pipe, so that a sufficient amount of heat can be obtained with a certain amount of current. It is an object of the present invention to provide a flexible fluid transport pipe and a method for heating the flexible fluid transport pipe.

According to a first aspect of the present invention, there is provided a flexible fluid transport pipe comprising: an inner pipe made of plastic; and a plurality of layers of metal tape spirally formed on the outer side of the inner pipe. What is claimed is: 1. A flexible fluid transport pipe comprising: a reinforcing layer provided by winding; and a protective layer provided by coating a plastic on the entire outside of the reinforcing layer, wherein an insulating layer is provided between the plurality of reinforcing layers. Is provided. In this case, the electric resistance of the reinforcing layer can be increased while maintaining the strength of the reinforcing layer sufficient for the internal pressure applied to the pipe, and a flexible fluid transport pipe capable of obtaining a sufficient calorific value with a certain amount of current can be provided.

A heating method for a flexible fluid transport pipe according to a second aspect is the method for heating a flexible fluid transport pipe according to the first aspect, wherein one of the plurality of reinforcing layers is provided. Alternatively, current is supplied to a plurality of layers. In this way, the flexible fluid transport tube can be easily heated with a relatively small current.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a flexible fluid transport tube. In FIG. 1, 1 is an inner tube, 2 is a cushion layer, 3 is a reinforcing inner layer, 4 is an insulating layer, 5 is a reinforcing outer layer, 6
Is a pressing tape layer, and 7 is a protective layer.

The inner tube 1 is made of a plastic such as polyethylene, vinyl chloride or the like, and a cloth tape, a rubberized cloth tape, a rubber tape or the like is wound thereon to form a cushion layer 2, and a stainless steel material is further formed thereon. The reinforcing layer is provided by winding a metal tape having excellent mechanical strength.

The reinforcing layer is composed of a plurality of layers, for example, a reinforcing inner layer 3 and an insulating layer 4 as shown in FIG.
A cloth tape, a rubberized cloth tape, a rubber tape or the like is wound on the metal tape of the above, and an insulating layer 4 is provided. The metal tape of the reinforcing outer layer 5 is further covered with the metal tape of the reinforcing inner layer 3. The gap is wound. Thus, the flexibility of the gas pipe is improved by winding the metal tape in the gap.

As described above, by providing the reinforcing layer including the reinforcing inner layer 3, the insulating layer 4, and the reinforcing outer layer 5 on the inner tube 1, the mechanical strength is increased while the flexibility of the inner tube 1 is maintained. And, even if the internal pressure in the middle and high pressure ranges is applied, it can withstand it. By interposing the cushion layer 2 between the inner pipe 1 and the reinforcing inner layer 3, the expansion of the inner pipe 1,
The stress applied to the reinforcing inner layer 3 when contraction or bending of the entire gas pipe occurs is reduced.

On the reinforcing outer layer 5, a pressing tape layer 6 is provided by winding a cloth tape, a rubberized cloth tape, a rubber tape or the like, and polyethylene, vinyl chloride, polypropylene, silicone rubber or the like is extruded and coated thereon. A protective layer 7 is provided. The pressing tape layer 6 prevents buckling of the reinforcing layer against bending of the entire gas pipe or the like. Also,
The protective layer 7 protects the internal reinforcing outer layer 5 and the like from mechanical damage and corrosion.

In such a flexible fluid transport pipe, the reinforcing layer is electrically separated into the reinforcing inner layer 3 and the reinforcing outer layer 5 by the insulating layer 4, so that the respective reinforcing inner layers 3 and 5 are cut off. The area can be reduced, and the electric resistance can be increased. Therefore, Joule heat is generated when a current is applied to either the reinforcing inner layer 3 or the reinforcing outer layer 5, and the amount of heat generation is proportional to I ² R when the magnitude of the current is I and the electrical resistance is R. Therefore, as the electric resistance R increases, the amount of generated heat increases accordingly, and a required amount of generated heat can be obtained without passing a large current. As a result, the tube can be sufficiently warmed, and the curl attached to the tube can be removed.

[0019]

EXAMPLE A flexible composite gas pipe having a length of 100 m and a specification of Table 1 was prepared and wound around a drum having a drum diameter of 3 m. Then, the number m of the wound gas pipes is released from the drum and the heat insulating material is wound thereon, and as shown in FIG. Do.
The current flowing at that time is about 100 A, and the flowing time is several tens of minutes.
It may be about one hour. By doing so, the flexible composite gas pipe can be heated to a temperature sufficient for straightening, for example, 75 ° C.

[0020]

[Table 1]

In the above embodiment, the metal tape of the reinforcing layer is provided in two layers of the reinforcing inner layer 3 and the reinforcing outer layer 5.
The present invention is not limited to this, and may be provided in three or more layers. In addition, at the time of heating, a current is supplied to one of the reinforcing outer layers 5, but a current may be supplied to both layers by connecting the reinforcing inner layer 3 and the reinforcing outer layer 5 in series at the ends.

[0022]

Since the present invention is configured as described above, it has the following effects. In other words, the flexible fluid transport pipe according to claim 1 has an inner pipe made of plastic, a reinforcing layer provided by spirally winding a plurality of layers of metal tape on the outer side of the inner pipe, and an outer side of the reinforcing layer. A flexible fluid transport pipe comprising a protective layer provided by entirely covering a plastic, wherein an insulating layer is provided between the plurality of reinforcing layers. As a result, it is possible to provide a flexible fluid transport pipe capable of increasing its electrical resistance while maintaining sufficient strength of the reinforcing layer against the internal pressure applied to the pipe, and obtaining a sufficient amount of heat generation without flowing a large current.

A heating method for a flexible fluid transport pipe according to a second aspect is the method for heating a flexible fluid transport pipe according to the first aspect, wherein one of the plurality of reinforcing layers is provided. Alternatively, since the flexible fluid transport tube is heated by energizing a plurality of layers, the flexible fluid transport tube can be easily heated.

[Brief description of the drawings]

FIG. 1 is a sectional view of a flexible fluid transport tube of the present invention.

FIG. 2 is a diagram showing a winding state of a reinforcing layer.

FIG. 3 is a diagram illustrating stresses in an inner layer and an outer layer of a reinforcing layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner tube 2 ... Cushion layer 3 ... Reinforcement inner layer 4 ... Insulation layer 5 ... Reinforcement outer layer 6 ... Holding tape layer 7 ... Protective layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshiyuki Makino, Inventor 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Kenichi Ishii 2-6-1, Marunouchi, Chiyoda-ku, Tokyo F-term in Furukawa Electric Co., Ltd. (reference) 3H111 AA02 BA03 BA12 BA15 BA17 BA29 CA03 CA52 CB07 CB10 CB14 CC03 CC04 CC07 CC18 DA07 DB12 EA12

Claims (2)

[Claims] 1. An inner tube made of plastic, a reinforcing layer provided by spirally winding a plurality of layers of metal tape on the outer side of the inner tube, and a protective layer provided by covering the entire outer side of the reinforcing layer with plastic. A flexible fluid transport pipe comprising: a flexible fluid transport pipe comprising: an insulating layer provided between the plurality of reinforcing layers. 2. The method for heating a flexible fluid transport pipe according to claim 1, wherein a current is supplied to one or more of the plurality of reinforcing layers. Tube heating method.