JPH06123385A - Fluid transporting pipe - Google Patents

Abstract

PURPOSE:To improve mechanical strength by forming a metal or plastic wire material in a spiral pipe form on an external pressure reinforcing body on the most inside layer of a composite pipe, and temporarily connecting the wire material with an oil soluble wax or plastic. CONSTITUTION:In a composite pipe, a wire material 7 consisting of FRP or aluminium alloy is molded into a spiral pipe form having required inner and outer diameters, a wax such as paraffin or plastic 8 easily dissolved in crude oil at a temperature of 100 deg.C or more is charged in the clearance between the adjacent wire materials 1 to temporarily bond the wire materials 1. On this external pressure reinforcing body 1, an oil resisting plastic main pipe 2, an internal pressure reinforcing layer 3, a middle plastic pipe 4, an axial force reinforcing layer 5, and a corrosion resisting plastic outer pipe 6 are provided. Thus, the spiral pipe is not expanded nor contracted by drawing tension, and the plastic main pipe can be extruded molded into determined inner and outer diameters. When such a transporting pipe is laid in a submarine oil field to start crude oil transportation, the wax or plastic 8 is dissolved, and sufficient flexibility and external pressure resisting buckling strength can be held.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid transportation pipe used for transporting high-temperature, high-pressure crude oil produced from a seabed oil field.

[0002]

2. Description of the Related Art A general structure of a conventional fluid transport pipe of this type is shown in FIG. The innermost layer has excellent resistance to external pressure buckling,
An external pressure reinforcing member 1 made of stainless steel having good corrosion resistance is provided. As shown in FIG. 4, the external pressure reinforcement body 1 has an interlock structure in which adjacent portions are engaged with each other. A plastic main pipe 2 which is a main body of a fluid transport pipe is provided on the external pressure reinforcing member 1 by extrusion molding. When the fluid is oil, the plastic main pipe 2 is often made of nylon which is excellent in workability and corrosion resistance and is flexible.

An internal pressure reinforcing layer 3 is formed on the plastic main pipe 2.
Is provided. The internal pressure reinforcing layer 3 is formed by closely winding two steel strips having a C-shaped cross section and a thickness of about 3 to 6 mm so that the openings face each other and are meshed with each other. An intermediate plastic pipe 4 is provided on the internal pressure reinforcing layer 3,
Further, an axial force reinforcing layer 5 is provided on it. In order to prevent the tube from extending in the axial direction due to the internal pressure, the axial force reinforcing layer 5 has a rectangular metal cross section with the winding direction reversed.
It is a long layer wound in layers. Further, the outermost layer is provided with an anticorrosion plastic outer tube 6 by extrusion molding. Each of the layers from the external pressure reinforcement body 1 to the plastic outer tube 6 has a structural feature that there is no force for restraining an adjacent layer other than a frictional force and each layer is a non-bonded composite structure.

[0004]

In the conventional fluid transport pipe, since the interlock pipe made of stainless steel is used as the outer pressure reinforcement body 1 of the innermost layer, the material cost is high and as shown in FIG. The processing cost for forming the interlock structure was high, which was a major factor in increasing the cost of the fluid transportation pipe. Therefore, there has been a demand for the development of a fluid transport pipe using a cheaper external pressure reinforcing member that does not impair the function of the external pressure reinforcing member.

[0005]

[Means for Solving the Problems] The following functions are required for the outermost pressure reinforcing member. Sufficient external pressure buckling strength. It has an auxiliary function to extrude a plastic main pipe into a perfect circle with a required diameter. Be careful not to scratch the plastic main pipe during the pig threading (inspection and cleaning of the inside of the fluid transportation pipe).

In order to reduce the cost of the fluid transportation pipe, the interlock pipe, which is the main factor of the cost increase in terms of material and manufacturing cost, is stopped, and the filament material is spirally formed at a small pitch as an external pressure reinforcing body. It is effective to adopt a spiral tube. In the case of a spiral tube, if an aluminum alloy or FRP (fiber reinforced plastic), which has a higher specific strength than stainless steel, is used as the filament material, there is no particular problem with respect to the above functions and When the plastic main pipe is extruded, the expansion of the spiral pipe fluctuates due to fluctuations in the take-up tension of the plastic main pipe, and the inner and outer diameters fluctuate, so the plastic main pipe is molded to the specified inner diameter and wall thickness. There is something that cannot be done.

Therefore, the present invention prevents fluid from being stretched by the take-up tension at the time of extrusion molding of the plastic main pipe, so that the spiral pipe can exhibit excellent flexibility when it is put into use after being manufactured. The tube is provided with a structure in which a wire material made of metal, plastic or fiber reinforced plastic is formed into a spiral tube having a required inner and outer diameters as an outer pressure reinforcing member of the innermost layer, and adjacent wire materials are formed. It is characterized in that a composite pipe is used in which is temporarily bonded with an oil-soluble wax or plastic.

[0008]

[Function] When such an external pressure reinforcing member is used, when the plastic main pipe is extruded, since the filament material constituting the spiral pipe is temporarily bonded with wax or plastic, the spiral pipe is pulled by tension. The plastic main pipe can be extruded into a predetermined inner and outer diameter without expansion and contraction. In addition, since the wax or plastic that temporarily bonds the filaments is oil-soluble, when the fluid transportation pipe is laid in the seabed oil field and crude oil transportation is started, the wax or plastic that was temporarily bonded to the filaments will dissolve. Finally, since only the spiral tube made of the linear material remains, it is possible to maintain sufficient flexibility and buckling strength against external pressure.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a vertical cross-sectional view of a fluid transportation pipe according to an embodiment of the present invention. This fluid transport pipe is characterized in that a composite pipe as shown in FIG. 2 is used as the outermost pressure-reinforcing body 1. That is, the composite pipe is formed by forming a filament material 7 made of FRP or an aluminum alloy into a spiral tube having a required inner and outer diameters, and forming a space between adjacent filament materials 1 by
A wax such as paraffin or a plastic 8 which is easily dissolved in crude oil at a temperature of 00 ° C. or higher is filled, and the adjacent linear materials 1 are temporarily bonded.

When the external pressure reinforcing member 1 has such a structure,
Material cost is lower than stainless steel interlock pipe,
Since it is easy to manufacture and has no elasticity, the plastic main tube 2 can be accurately extrusion-molded thereon with a predetermined inner and outer diameters. As in the conventional case, the oil resistant plastic main pipe 2, the internal pressure reinforcing layer 3, the intermediate plastic pipe 4, the axial force reinforcing layer 5 and the anticorrosion plastic outer pipe 6 are sequentially provided on the external pressure reinforcing body 1.

The external pressure reinforcing member 1 has the above-described structure at the time of manufacturing the fluid transportation pipe. However, when it is laid in a seabed oil field or the like and the crude oil transportation is started, the oil-soluble wax or the plastic 8 is melted, and finally. Only the spiral tubular filament 7 remains. Since the helical tubular filament 7 has sufficient flexibility and resistance to external pressure buckling, it sufficiently fulfills the function of the plastic main tube 2 as an external pressure reinforcing member.

[0012]

As described above, according to the present invention, a composite pipe in which a wire rod formed into a spiral pipe is temporarily joined with an oil-soluble wax or plastic instead of the interlock pipe as the outer pressure reinforcing member of the innermost layer. By using, it is possible to obtain a fluid transport pipe that is inexpensive and has excellent mechanical strength.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a fluid transportation pipe according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing an external pressure reinforcing member used for the fluid transport pipe of FIG.

FIG. 3 is a perspective view showing a conventional fluid transport pipe.

FIG. 4 is a vertical cross-sectional view showing an external pressure reinforcing body used in the fluid transport pipe of FIG.

[Explanation of symbols]

1: External pressure reinforcement 2: Plastic main
3: Internal pressure reinforcement layer 4: Intermediate plastic pipe 5: Axial force reinforcement layer 6:
Corrosion-proof plastic outer tube 7: Spiral shaped filament material 8: Oil-soluble wax or plastic to temporarily bond filament material 7

Claims (1)

[Claims] 1. A fluid transportation pipe having an outer pressure reinforcing member in the innermost layer, and having an oil-resistant plastic main pipe, an inner pressure reinforcing layer, an axial force reinforcing layer and an anticorrosion plastic outer pipe on the outer periphery thereof.
The external pressure reinforcing member is a composite pipe in which a wire rod made of metal, plastic or fiber reinforced plastic is formed into a spiral tube having a required inner and outer diameters, and adjacent wire rods are temporarily bonded with an oil-soluble wax or plastic. A fluid transportation pipe characterized by comprising.