JPH02225895A - Flexible liquid transport tube - Google Patents

Abstract

PURPOSE:In a flexible liquid transport tube consisting of an inner tube, a reinforcing layer and a protection sheath layer, to improve the flexibility and the fatigue resistance and to make the installation of the tube easy by constructing either one of the inner tube or the protection sheath layer with polyolefin resin or the like. CONSTITUTION:The flexible liquid transport tube is constructed with an inner tube 1 through which desired liquid is transported, a reinforcing layer 2 provided on the outside of the inner tube 1, and a protection sheath layer 3 covered on the periphery of the reinforcing layer 2. At least either one of the inner tube 1 or the protection sheath layer 3 is made of synthetic resin. As for the synthetic resin, either one of a polyolefin resin of less than 7000kg/cm<2> in apparent modulus of elasticity and of excellent fatigue resistance, or an olefin copolymer resin or an olefin based composite can be used. As the result, the flexibility and the fatigue resistance of the tube can be improved, the transportation and the installation of the tube can be made easy, and the breakdown of the tube due to the repeated bending force during a long term can be prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fluid transport pipe used for transporting fluids such as water, oil, chemicals, gas, etc. The present invention relates to a flexible fluid transport pipe that can withstand bending and transport various desired fluids.

[Conventional technology]

BACKGROUND ART Conventionally, for example, flexible fluid transport pipes using nylon resin for the inner pipe and protective sheath layer have been used to transport fluids such as oil and gas obtained from oil fields on the ocean floor. Although nylon resin has low gas permeability, due to the high pressure of the fluid flowing through the inner tube, gas or gas components in the fluid permeate from the inside of the inner tube to the outside.

[Problem to be solved by the invention]

However, the gas or gas components have difficulty permeating and diffusing through the protective sheath layer made of nylon resin with low gas permeability due to the pressure drop, and therefore accumulate in the reinforcing layer between the inner tube and the protective sheath layer. Eventually, the gas pressure increases, causing damage to the protective sheath, or, in the case of harmful gases such as H and S, corroding the metal reinforcing layer, resulting in problems such as shortening the life of the transport pipe.

For this reason, it is conceivable to use polyethylene as a material constituting the protective sheath layer, but in applications where the protective sheath layer is subjected to repeated bending, the protective sheath layer will break in a short period of time.

Furthermore, in water injection lines for offshore oil fields and the like, since polyethylene has insufficient fatigue resistance, polyethylene resin is used for both the inner tube and the protective source layer, but it is expensive.

Also, when water is being sent to remote islands, high-density polyethylene is used as the material for the inner pipe, but it is too rigid and difficult to bend, making it difficult to handle during installation, etc.

[Means to solve the problem]

The present invention is inexpensive, has an excellent gas permeability coefficient, and has flexibility.
In addition, the above drawbacks are improved by using a polyolefin resin with a limited range of properties that can withstand repeated bending for at least one of the inner tube and the protective source layer.

More specifically, the present invention includes: an inner tube through which a desired fluid passes; a reinforcing layer provided on the outside of the inner tube;
Furthermore, in the flexible fluid transport tube composed of a protective sheath layer covering the outer periphery of the reinforcing layer, the material constituting at least one of the inner tube or the protective sheath layer has an apparent elastic modulus of 7000 kg/cj or less. , a polyolefin resin with excellent fatigue resistance, a polyolefin copolymer resin, or a polyolefin-based composition.

[For production]

If the polyolefin resin or the like having an apparent modulus of elasticity exceeding 7000 kg/- is used as the material constituting at least one of the inner pipe or the protective sheath layer, the desired bending rigidity as a transport pipe cannot be obtained, and transportation and installation of the pipe are difficult. Moreover, the fatigue resistance of the inner tube or the protective sheath layer is poor, and cracks may occur if bending force is repeatedly applied to the inner tube or the protective sheath layer.

Here, the superiority or inferiority of fatigue resistance is determined based on ASTM D671-63 sorting of 5n thick molded by heat press.
A smooth specimen specified by T (A method) was cut or punched and subjected to a constant strain amplitude cantilever bending test at an amplitude of ±20 blades and a test speed of 20 to 25 cycles/sec. It is determined whether the total number of test cycles until breakage or visible cracks occur when tested at room temperature is 10' or more. Excellent fatigue resistance is determined by the total number of test cycles mentioned above. is 10' times or more. Materials that break after a number of times less than this number will undergo fatigue failure early in the application of the present invention and will not be of practical use.

In the present invention, the inner tube and A flexible fluid transport tube using a material with such physical properties, which is preferably used as a material constituting the protective sheath layer, but may also be used as a material constituting either the inner tube or the protective sheath layer. has excellent flexibility and fatigue resistance, is easy to transport and install, and does not break due to repeated bending force over a long period of time, making it possible to supply high-quality and inexpensive transport pipes to the market. .

(Example) Next, an example of the present invention will be described. Fig. 1 is a side view showing a flexible fluid transport pipe of the present invention, and shows an inner pipe 1 through which a desired fluid is passed. , a reinforcing layer 2 provided on the outside of the inner tube 1, and a protective sheath layer 3 covering the outer periphery of the reinforcing layer 2.

Reinforcement! ii2 is formed by wrapping a steel strip with a concave cross section with a similar pinch so that the inner layer faces outward and the outer layer faces inward, and the inner and outer concave portions engage, so as to be able to withstand internal pressure sufficiently. The inner reinforcing layer 2a is formed by winding flat steel strips in two layers with long pitches, and the outer reinforcing layer 2b is made to withstand tensile force in the axial direction.

The material constituting at least one of the inner tube 1 and the protective sheath layer 3 has an apparent elastic modulus of 7000 kg.
/cd or less and has excellent fatigue resistance, examples of polyolefins shown in the table below include propylene copolymer resin (5FX9830 from Mitsubishi Yuka), silane crosslinkable polyolefin resin composition (Linkron from Mitsubishi Yuka), XF800,
There is a Linkron MF70ON>.

/' Example 1 A steel strip with a concave cross section, a thickness of 31 layers, and a radius IQms was placed on an inner tube 1 made of nylon with an inner diameter of 7.5 (J and a wall thickness of 5I), with the inner layer facing outward. , the outer layer is wound inward with short pitches so that the inner and outer concave portions engage with each other to form the inner J11i1.
A flat steel strip with a thickness of 1°C and a thickness of 31 mm and a width of 81 mm is used as an inner layer and 35 pieces are wound at a corner of 37 degrees, and 37 pieces are wound as an outer layer in the opposite direction at a corner of 33 degrees. '' to form an outer reinforcing layer 2b and provide reinforcement Iw2, and furthermore, a propylene copolymer resin (product name: Mitsubishi Yuka
A protective sheath layer 3 made of 5PX9830) was coated.

An airtight end joint was attached to the transport pipe prototyped in this way, and the inside of the transport pipe was heated to 80°C with a heater.
Helium gas was sealed inside. In addition, water at 18° C. was poured over the protective sheath jli3. As a result, the pressure in the reinforcing layer 2 between the inner tube 1 and the protective sheath layer 3 was initially 0 kg/cj, but after 30 days it became 1 kg/cd. One year later, the protective sheath layer 3 continued to swell, but it did not bank.

Comparative Example 1 Protective sheath layer 3 was added to the same transport pipe up to the inner pipe 1 and the reinforcing layer 2.
When we conducted the same experiment as in Example 1 using nylon with a wall thickness of 5 mm and measured the reinforcing N2 gas pressure, the pressure became 5 kg/- after 30 days, and the
After a few days, the protective sheath layer 3 was punctured.

Example 2 A bending fatigue test was conducted in which the same 14 m transport pipe as in Example was fixed at one end in a U-shape with a span of 6 m, and the other end was repeatedly bent with a vertical stroke of 3 m.

As a result, no abnormality was observed in this transport pipe even after 3 million cycles.

Comparative Example 2 Protective sheath layer 3 was added to the same transport pipe up to inner pipe 1 and reinforcing layer 2.
The same bending fatigue test as in Example 2 was conducted using high-density polyethylene shown in the table above with a meat Iv5ms. As a result, the protective sheath layer 3 broke after 120,000 cycles! occurred.

Note that the polyolefin having the above physical properties may be used as a material forming the inner tube 1 or as a material forming both the inner tube and the protective sheath.

〔Effect of the invention〕

The effects of the present invention are as follows. That is, as a material constituting at least one of the inner pipe or the protective sheath constituting the transport pipe, a polyolefin resin or a polyolefin copolymer resin having an apparent modulus of elasticity of 7000 kg/cj or less and excellent fatigue resistance, or By using one of the materials of the polyolefin-based composition, it has excellent flexibility and fatigue resistance, is easy to transport and install, and does not break under the action of repeated bending force between pipes. Therefore, it is possible to provide high quality and inexpensive transport pipes.

[Brief explanation of the drawing]

FIG. 1 is a side view showing an embodiment of the present invention. l-111 inner tube, 2-11~reinforcing layer, 2a-1 inner reinforcing layer, 2b---1 outer reinforcing layer, 3-111 protective sheath layer. Patent applicant Furukawa Electric Co., Ltd.

Claims (1)

[Claims] A flexible fluid transport tube comprising an inner tube through which a desired fluid is conveyed, a reinforcing layer provided on the outside of the inner tube, and a protective sheath layer covering the outer periphery of the reinforcing layer,
The material constituting at least one of the inner tube or the protective sheath layer has an apparent elastic modulus of 7000 kg/cm.
A flexible fluid transport pipe characterized by using any one of a polyolefin resin, a polyolefin copolymer resin, or a composition based on polyolefin, which has a polyolefin resin having a tensile strength of ^2 or less and has excellent fatigue resistance.