JPS6388390A - Flexible fluid transport pipe - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flexible fluid transport pipe for transporting fluids such as natural gas and crude oil containing gas.

[Conventional technology]

For flexible transport pipes that transport fluids such as natural gas and gas-containing crude oil, a reinforcing layer made of metal or FRP material is provided on the plastic inner pipe to withstand internal pressure and tension in the pipe axis direction. As the outermost layer thereon, a plastic sheath is used to prevent damage and corrosion of the reinforcing layer.

Generally, plastic materials cannot completely shield gases, and gases diffuse and permeate through the plastic. The higher the pressure and temperature, the greater the amount of gas permeation tends to be.

Therefore, even in the case of the flexible fluid transport pipe, gas components such as oxygen and hydrogen sulfide in the fluid permeate through the plastic inner pipe and enter the space between the plastic inner pipe and the plastic jacket during fluid transport. Accumulated as permeate gas.

[Problem that the invention seeks to solve]

Although the amount of gas permeation is small, if the permeation pressure reaches a certain high pressure proportional to the internal pressure of the plastic inner tube over a long period of time, the plastic outer jacket will be destroyed by this pressure.

In order to prevent this, some thin walled parts are locally provided in the plastic sheath to promote the release of the above-mentioned permeable gas outside the plastic sheath. However, if the reinforcing layer is a metal reinforcing layer, it may corrode due to infiltrated seawater, reducing the service life of the transport pipe.

It is also possible to construct the plastic outer jacket with a material that has better gas permeability than the plastic inner tube, such as silicone rubber, but these materials do not have sufficient moldability, wear resistance, or mechanical properties, and are of poor quality. Couldn't get a transport tube.

Furthermore, some products have a gas shielding layer made of metal tape, but when used in an environment where the transport pipe is repeatedly bent, this metal tape can break due to fatigue, reducing the gas shielding effect and resulting in poor reliability. .

[Means for solving problems]

The present invention eliminates the above-mentioned drawbacks and provides a flexible fluid transport pipe that suppresses gas permeation and prevents the plastic jacket from breaking. In a flexible fluid transport pipe having a plastic outer covering thereon, the gas permeability coefficient constitutes the plastic inner pipe between the plastic inner pipe and the reinforcing layer or in the pipe wall of the plastic inner pipe. 1/of the material
It is characterized in that a gas shielding layer made of a plastic material having a molecular weight of 10 or less is interposed therebetween.

[For production]

According to the configuration of the present invention, since the amount of gas components in the fluid that permeate through the plastic inner tube during fluid transportation is reduced, it is possible to prevent the plastic outer jacket from being destroyed and also to prevent gas from permeating. The air-tightness and liquid-tightness of the transport pipe are higher than those with a mechanism in which the pipe is released by releasing the pipe, and the plastic jacket is less likely to be damaged or infiltrated by seawater, and mechanical strength can be maintained. In addition, it does not emit harmful gases and can maintain a good surrounding environment, and is resistant to repeated bending of the transport pipe and can withstand long-term use.

〔Example〕

Next, an embodiment of the present invention will be explained in detail with reference to the drawings. Fig. 1 shows an embodiment of a flexible fluid transport pipe 10 according to the present invention, and this transport pipe 10 is made of, for example, nylon 11 or nylon. On the plastic inner tube 12 consisting of 12,
A circumferential reinforcing layer 14A made of metal strips wound at short pitches to withstand internal pressure, and an axial reinforcement layer 14A made of metal strips wrapped at long pitches to withstand tension in the tube axis direction. A reinforcing layer 14 made of striations 14B is provided, and a plastic outer sheath 1 made of polyethylene, nylon, etc. is provided thereon.
It has a structure covered with 6.

Furthermore, in the embodiment shown in FIG. 1, a gas barrier layer 18 is interposed between the plastic inner tube 12 and the reinforcing layer 14. In other words, the gas shielding layer 18 is provided directly above and in contact with the plastic inner tube 12 . This gas shielding layer 18 is made of an extruded or tape-wrapped coating layer of a plastic material such as polyvinylidene chloride, polyvinyl alcohol, polyacrylonitrile, polynisdel, or the like.

The gas permeability coefficients of the various materials mentioned above are as follows.

Gas permeability coefficient (crl (STP) c+n/cnbsec・cmHg)
Nylon 12 0.06 Nylon 6 0.010 Polyvinylidene chloride 0.0009 Polyvinyl alcohol 0.00045 Polyacrylonitrile 0.00012 The above gas permeability coefficient is 20°C
Under this environment, one side of a film with a thickness of 10 to 500 μm was kept in vacuum, and a constant pressure was applied with nitrogen gas from the other side.

The difference in pressure was used to detect the pressure rise on the vacuum side using a Baratron pressure transducer.

FIG. 2 shows another embodiment of the present invention, in which the gas shielding layer 18 shown in FIG. It is designed to be buried in the pipe 12 as an intermediate layer, and the other structure is the same as that shown in FIG.

[Experiment example]

Next, the following experiment was conducted to confirm the effect of the fluid transport pipe 10. That is, a sheet with a three-layer structure in which a polyvinylidene chloride film with a thickness of 0.5 mm was interposed between two sheets of nylon 11 with a thickness of 1 nm was used as a sample, and this was
The sheet was sandwiched from both sides with 7-flange cross-sectional flange for OKG/CRA, and 15 kg/d of nitrogen gas was applied from a nitrogen gas cylinder into one flange in an environment of 40°C, and the pressure gauge attached to the other flange was applied. When the pressure (gauge pressure) of the gas passing through the sheet was measured after 104 minutes, the detected pressure was very small, less than 1 kg/cffl (almost the same pressure as atmospheric pressure), indicating that the gas shielding The effect was sufficient.

[Comparative Example 1] In an experiment using the same 7 mats, the pressure of gas permeating through a sheet with a three-layer structure in which the film interposed between the nylon 11 sheets was a nylon 6 film with a thickness of 0.5 m was measured. It was 0.31 kg/cT+f, and the gas shielding effect was not sufficient.

[Comparative Example 2] A steel plate having 6 slits with a width of 2 mm was pressed against one side of a nylon 11 sheet with a thickness of 2 mm, and the pressure of the permeating gas was measured under the same measurement conditions as the above experimental example. ,0
．． It became 48 kg/i, and the gas shielding effect further decreased.

As can be seen from the above example, the gas shielding layer 18 has a gas permeability coefficient that is 1/2 that of the material constituting the plastic inner tube 12.
A sufficient gas shielding effect can be obtained by constructing the plastic material with a gas permeability coefficient of 10 or less (for example, polyvinylidene chloride); It was confirmed that when constructed from nylon 6), a sufficient gas shielding effect could not be obtained.

〔Effect of the invention〕

As explained above, the present invention provides a structure in which the gas permeability coefficient is higher than that of the material constituting the plastic inner tube between the plastic inner tube and the reinforcing layer of the flexible fluid transport tube or in the tube wall of the plastic inner tube. Since the gas shielding layer is made of a plastic material that is 1/10 or less, the amount of gas components in the fluid that permeate through the plastic inner tube during fluid transport is reduced, and therefore the plastic inner tube and the plastic outer jacket are It does not accumulate above a certain pressure as permeated gas in the space between
Destruction of the plastic jacket can be prevented.

In addition, compared to the structure in which the permeated gas is released outside the plastic jacket, the plastic jacket is less damaged and has stronger mechanical strength, and is highly airtight and liquid-tight, allowing harmful gases such as hydrogen sulfide to escape. There is no pollution caused by the release of

Furthermore, since the gas shielding layer is made of plastic material, it will not break even if repeated bending force is applied to the transport pipe (
It can be used stably for a long period of time in the ocean, where many repeated bending forces are applied, and has the effect of extending its service life.

[Brief explanation of the drawing]

1 and 2 are side views showing different embodiments of the present invention. DESCRIPTION OF SYMBOLS 10... Flexible fluid transport pipe, 12... Plastic inner tube, 14... Reinforcement layer, 14A... Circumferential reinforcement layer, 14B... Axial force reinforcement layer, 16... - Plastic jacket, 18... gas shielding layer.

Claims (1)

[Claims] In a flexible fluid transport pipe formed by providing a reinforcing layer on a plastic inner pipe and covering the reinforcing layer with a plastic outer jacket,
A gas shielding layer made of a plastic material having a gas permeability coefficient of 1/10 or less of that of the material constituting the plastic inner tube is provided between the plastic inner tube and the reinforcing layer or in the tube wall of the plastic inner tube. A flexible fluid transport pipe characterized in that it is interposed.