JPS616485A - Transport pipe for high-temperature fluid - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pipeline used for transporting high-temperature water, oil, gas, etc.
The present invention relates to a high-temperature fluid transport pipe that can transport various desired fluids.

Traditionally, for example, Chichitsu pipes have been mainly used to transport oil, gas, gas, etc. obtained from oil fields on the ocean floor, but in recent years, flexible composite pipes have been attracting attention due to their ease of construction. ing.

For example, this flexible composite tube is manufactured by the French company Kotrekiship and has Z-shaped short-pitch reinforcing strips and flat long-pitch reinforcing strips on the inner tube made of nylon, as needed. Composite tubes with a plastic sheath and a plastic sheath are sold. This composite pipe is used to transport crude oil and gas in many offshore oil fields, but
The temperature of oil gushing out from oil wells sometimes exceeds 100°C, and if used in such locations, oil leaks may occur in a fairly short period of time.

That is, for the conventionally used inner tube made of nylon resin, 100° C. is considered to be the limit temperature for use, and a long service life cannot be guaranteed at such a temperature.

On the other hand, as heat-resistant resins that can replace nylon resins, fluororesins and various engineering plastics are generally considered, but for the manufacture of high-temperature and high-pressure transportation and pipes,
It was assumed that the elongation would be insufficient or that stress cracking would occur in the neck, so its practical application had not progressed.

That is, for example, polyvinylidene fluoride resin is known for its excellent extrusion processability, heat resistance, and chemical resistance.
Although it has been put into practical use for pipe lining, solid pipes, etc., its application to flexible pipes has not been known except for extremely thin pipes.

The reason for this is that polyvinylidene fluoride resin has high rigidity, so even if it is used for applications such as the present invention, it can be cut with a saw, etc., especially in winter, due to its low temperature. When I try to do it, it.

It often happens that cracks propagate over a distance of 100 m, rendering the product unusable.

The cause of this is not only the high rigidity of the polyvinylidene fluoride resin, but also the high molding shrinkage rate of the resin itself, and the problem is considered to be the large residual strain of the molded product. In other words, flexible interlock metal is made by winding metal strips while interlocking with each other, and a tube obtained by directly extruding and coating a round tube with polyvinylidene fluoride resin is bent and notched. ,
When the propagation of the crank was observed, it was found that the cracks originated from the recesses (protrusions of the resin molded product) in the meshing portion of the metal tubes.

The present invention takes advantage of the characteristics of polyvinylidene fluoride, which has excellent heat resistance, and also provides a high-temperature fluid transport pipe that can be used at high temperatures and high pressures and has excellent flexibility, while improving the above-mentioned drawbacks. That is.

That is, the present invention has been achieved as a result of various research studies conducted by the inventors as described above, and an embodiment of the present invention, as shown in the drawings, is an inner pipe through which a desired high-temperature and high-pressure fluid is passed. , a reinforcing layer provided on the outside of the inner pipe, and a protective sheath layer covering the outer periphery of the reinforcing layer. Izotsu impact strength is 10 kgcm
/crn or more, a polyvinylidene fluoride copolymer resin with an apparent Young's modulus of 9 (19/- or less), or a blend of a polyvinylidene fluoride resin, a resin, and the above copolymer resin, or the above polyfluoride resin. The present invention is characterized in that a pipe is extruded using any of the compositions based on vinylidene copolymer resin.

In the present invention, the reason why the constituent material of the inner tube is specified as described above is that if the material of this kind has an Izot impact strength of less than 1 Q kg Cm/Cm, the impact strength is too weak and cannot be used. This is also because if the apparent Young's modulus exceeds 90 kg/mJ, there is a risk of cracking or cracking.

In addition, the polyvinylidene fluoride copolymer resin referred to in the present invention includes vinylidene fluoride monomer as a main component, 4-fluorinated ethylene monomer, 3-fluorinated 1-rt ethylene monomer, 6-fluorinated propylene monomer, etc. It is a resin obtained by copolymerizing one or more comonomers.

In addition, in the present invention, the reason why the measurement of impact strength for specifying the inner pipe constituent material is limited to testing from sheets made by heat pressing is that the heat pressing method is easy to prepare test pieces.
This is also because the measured values are obtained at low l/) values.

In addition, for the fluid transport pipe of the present invention, for use in places where it is necessary to withstand high pressure such as deep sea, a flexible interlocking metal pipe made by interlocking metal tapes on the inside of the inner pipe is used. Although the interlocking metal tube is inserted, it is preferable to use one having a plastic tape wrap layer provided on the outer circumferential surface of the interlocking metal tube.

The reason for this is that the interlocking metal tape engagement part of the interlocking metal pipe is concave, and when the inner tube is directly extruded onto this, the tube material bites into the concave part. This is because it is possible to suppress the occurrence of the phenomenon that, due to the wall thickness, etc., that part often becomes a source of cranking in subsequent processes.

Further, in the present invention, the reinforcing layer provided on the outside of the inner tube has the function of withstanding internal pressure, and is usually made of metal or reinforced plastic bands, strips, wires, or the like.

In addition, if the reinforcing layer is composed of short-pitch irregular cross-section strips and reinforcing strips wound at least two layers with long pitches in different winding directions, the former reinforcing strips will mainly act on the pipe. It serves to withstand circumferential stress due to pressure, and the latter may serve to withstand axial stress due to internal pressure acting on the tube.

Furthermore, if strips of fiber-reinforced plastic A with a multi-projection cross-section are used as the reinforcing layer material, an appropriate amount of space can be provided between the strips of the reinforcing layer, and as a result, cooling from the outside can be prevented. It will be done.

The present invention will be explained below with reference to Examples and Comparative Examples.

Example 1 Polyvinylidene fluoride copolymer resin obtained by reacting vinylidene fluoride monomer and 3-1-fluoride-enalene chloride monomer at a molar ratio of 9=1 (prepared by hot pressing and made into two sheets) Izot powder sheet strength 11.6~mr/M-1, 11
) A pipe with a wall thickness of 4 m x 7 mm and an inner diameter of 2 inches was extruded using a Young's modulus of 5 (3.8 kg/mJ). Next, install 0.6 afi/ac on the outside of the pipe.
t, and 1. Iron strips with a thickness of 50 m/ra and a width of 50 mm are wound in two layers each with a gap of 5 m/m, and then a 6 m/m wire is wound at a winding angle of 15°.
Change the winding direction of the two layers and wind C, and on top of this, 4 +
A transport tube was prepared by extrusion coating +w/ram thick polyethylene.

In the above manufacturing process, the pipe made of polyvinylidene fluoride copolymer resin was rolled up around a drum with a diameter of 1 m, and no abnormality occurred.

The thus obtained transport pipe maintained the internal pressure breakdown characteristics of 5001C9/cffI.

Comparative Example Example using polyvinylidene fluoride obtained by reacting only vinylidene fluoride monomer (Izot impact strength by hot press sheet method: 7.2 jay am/cm, apparent Young's modulus: 88.2 kg/sj) An attempt was made to make the same transport pipe as in Example 1 by extrusion molding a pipe of the same size as Example 1, but a crack occurred in the pipe during the first drum winding during the process.

Examples 2 to 4 and Comparative Example 2 The resins and resin compositions shown in Examples 2 to 4 and Comparative Examples 2 to 3 were placed on a 1-inch inter-four pipe 1 made of SUS 804 using an extruder. Extrusion coatings were carried out with a thickness of m/m (see table). This formed tube, that is, the inner tube 8, was bent to a radius of 22 Cta, and a notch with a length of about 2 ry was made with a knife to check the propagation of cracks. The results are shown in the table. If there are no cracks, stretch it in a straight line°
Bending C1 again R22 Bending to Cjll was repeated up to 20 times. The result was separately made by heat pressing 6
The Izod impact test value measured with a thick sheet and the tensile Young's modulus measured with a 1 inch thick sheet are also shown. Crack data is shown as the lowest value after testing 5 pieces.

Regarding the above table, the Izot impact test was conducted using a sample having a thickness of 6111111.

Young's modulus is punched out from a sheet with a thickness of 1 mm and a size 2 dumbbell.
It is determined from the initial slope of the strain-strength curve obtained by stretching at 50 mm/ml (23°C).

Example 5 In Example 2, the 1-inch interlock tube 1
Then, a plurality of layers of polyester tape are wound to a thickness of 0.5 m/m to wrap the recessed part of the interlocking tube 1 to form a plastic tape layer 2, and a polyvinylidene fluoride copolymer is placed on top of the plastic tape layer 2. Resin (trade name: Foracron 650HD, Izotsu impact test 11 lc9 Cr
n/”z apparent Young’s modulus 88 kg/ma)
A tube, that is, an inner tube 8, was obtained by extrusion coating to a thickness of 3 m/m. When this tube was evaluated in the same manner as in Examples 2 to 4, it was found that no blurring occurred up to 20 times.

In addition, even if the resin of Comparative Example 2 is molded in the same way, the number of repetitions is 6.
Cracks occurred at times.

The effect of the tape 2 that wraps the polyester film or the like on the flexible metal tube, that is, the interlock tube 1, is that the polyvinylidene fluoride copolymer resin on the outside of the tape 2 wraps around the flexible metal tube 1 in the cut-in part. In addition to preventing it from entering,
It is believed that laminating a plurality of sheets provides a certain degree of cushioning, which has the effect of reducing the occurrence of local strain in the resin when bent, as well as releasing molding strain.

Example 6 In Example 2, the °C1 interlock '11 was made 8 inches, and polyester tube 2 was wound thereon in multiple layers to a thickness of 0.51, and then an inner tube 3 with a wall thickness of 6 m/m was formed.
on top of which two layers of steel strips 4 having a concave cross-sectional shape (U-shaped strip) are placed so that the openings and legs of the strips engage with each other (thickness of the two engaged layers (l mm), A flat steel strip 5 with a rough thickness of 3 mm was wound at an angle of 40°, and a resin layer 6 made of low-density polyethylene was further coated on the outside.

After oil heated to 120°C was circulated through the transport pipe thus completed, equilibrium was reached and an internal pressure failure test was conducted, resulting in failure at 950 kg/c-.

Note that the surface temperature at this time was 50°C.

On the other hand, an attempt was made to construct a similar transport pipe using the resin of Comparative Example 2, but when attempting to cut the recessed strip 4 with a saw before winding it, cracks propagated in the longitudinal direction of the pipe.

Example 7 In Example 6, the resin of the inner tube 8 used was changed from Example 8 (
Same as Example 6, except that instead of the flat steel strip 4 with a thickness of 8 squares, a strip made of fiber-reinforced plastic with the same cross-sectional area and cross-shaped cross section was used. A transport pipe constructed as follows was obtained. When the same evaluation was performed on this, the internal pressure burst strength was 850~/cr &
Met. Further, the surface temperature of the tube at this time was 38° C., which provided a higher degree of heat retention than the tube of Example 6.

The effects of the present invention are as follows. In other words, we have specially selected polyvinylidene fluoride resin, which itself has particularly excellent heat resistance, from a limited range of properties, and successfully applied it to the inner tube instead of conventional nylon. A high-temperature fluid transport pipe whose properties can be significantly improved can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic side view in partial section of an embodiment of the present invention. 1... Interlock tube 2... Plastic (polyester, etc.) film or tape 8... Polyvinyl fluoride IJ Den copolymer resin 4... U-shaped strip (radial strip with concave cross section) 5... Flat strip 6... Polyethylene. Patent applicant Furukawa Electric Co., Ltd. Figure 1

Claims (1)

[Claims] 1. An inner pipe through which a high-temperature, high-pressure desired fluid is passed;
In a high-temperature fluid transport pipe composed of a reinforcing layer provided on the outside of the inner pipe and a protective sheath layer covering the outer periphery of the reinforcing layer, the inner pipe is subjected to an izot impact of a sheet made by heat pressing. A polyvinylidene fluoride copolymer resin having a strength of 10 kgcm/cm or more and an apparent Young's modulus of 90 kg/mm^2 or less, or a blend of a polyvinylidene fluoride resin and the copolymer resin, or the polyvinylidene fluoride resin and the copolymer resin. A high-temperature fluid transport pipe characterized by using a pipe extruded using any of the compositions based on vinylidene fluoride copolymer resin. 2. A flexible interlocking metal tube formed by interlocking metal bands with a plastic tape wrapping layer is disposed inside the inner tube, and a 2. The high-temperature fluid transport pipe according to claim 1, wherein the reinforcing layer is formed by winding a reinforcing layer made of metal or fiber-reinforced plastic. 3. The reinforcing layer is characterized by comprising a reinforcing strip having an irregular cross-sectional shape, which is wound at a short pitch, and a reinforcing strip, which is wound at a long pitch in at least two layers with mutually different winding directions. A high-temperature fluid transport pipe according to claim 2. 4. Claim 3, characterized in that the reinforcing layer is composed of reinforcing strips made of fiber-reinforced plastic, and the reinforcing strips are wound at long pitches and have a multi-projection cross section. Transport pipe for high temperature fluid as described.