JPH0556437B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a transport pipe used for transporting high-temperature water, oil, gas, etc., and particularly relates to a high-temperature fluid transport pipe that is flexible, can withstand high pressure and high temperature, and can transport various desired fluids. It is something. Conventionally, iron pipes have been mainly used to transport oil, gas, etc. obtained from oil fields on the ocean floor, but in recent years, flexible composite pipes have been attracting attention because of their ease of construction. For example, this flexible composite tube is manufactured by the French company CoflexiP and has Z-shaped short pitch reinforcing strips and flat long pitch reinforcing strips wrapped around the inner tube made of nylon as necessary. Composite tubes are available that are rotated and have a plastic sheath. This composite pipe is used in many offshore oil fields.
It is used to transport crude oil and gas, but the temperature of the oil gushing out from oil wells can sometimes exceed 100 degrees Celsius, and if it is used in such places, it can cause an oil leak accident in a fairly short period of time. may occur. In other words, 100℃ is considered to be the maximum operating temperature for the conventionally used nylon resin inner tube.
At such temperatures, a long service life cannot be guaranteed. On the other hand, fluororesin and various engineering plastics are generally considered as heat-resistant resins to replace nylon resins, but they lack sufficient elongation and stress cracking to manufacture high-temperature, high-pressure transport pipes. Problems were expected to arise, and no progress had been made in its practical application. For example, polyvinylidene fluoride resin is known for its excellent extrusion processability, heat resistance, and chemical resistance, and has been put into practical use for pipe lining, solid pipes, etc.; No application to pipes was known, except for very thin pipes. The reason for this is that polyvinylidene fluoride resin has high rigidity, so even when used for applications such as the present invention, it is difficult to cut it with a saw, etc. while it is bent, or after stretching it, due to its low temperature, especially in winter. Then,
Cracks often propagate over tens of meters, making them 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. That is, a flexible interlocking metal tube made by winding metal tapes while interlocking with each other is directly extruded and coated with polyvinylidene fluoride resin, and then bent and notched. When observing the propagation, it was found that the cracks originated from the recesses (protrusions of the resin molded product) in the metal tube meshing part. 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 as can be seen in the drawings, an embodiment of the present invention is a system for transmitting a desired high-temperature and high-pressure fluid through the interior. , a flexible interlock metal tube formed by molding metal tapes and interlocking with each other, an inner tube covering the outer periphery of the interlock metal tube, a reinforcing layer provided on the outside of the inner tube, and a reinforcing layer provided on the outside of the inner tube. In a fluid transport pipe composed of a protective sheath layer covering the outer periphery of a reinforcing layer, the inner pipe has a sheet made by heat pressing that has an Izot impact strength of 10 Kgcm/cm or more and an apparent Young's modulus of 10 Kgcm/cm or more.
Any of a polyvinylidene fluoride copolymer resin having a weight of 90 Kg/mm ² or less, a blend of a polyvinylidene fluoride resin and the above copolymer resin, or a composition based on the above polyvinylidene fluoride copolymer resin It is characterized by using an extrusion-molded pipe. In the present invention, the reason why the constituent material of the inner tube is specified as described above is that it is impossible to use such a material with an Izot impact strength of less than 10 Kgcm/cm because the impact strength is too low. This is because if the apparent Young's modulus exceeds 90 kg/mm ² , cracks and tears may easily occur. In addition, the polyvinylidene fluoride copolymer resin referred to in the present invention includes vinylidene fluoride monomer as a main component, 4-ethylene fluoride monomer, 3-fluoride 1
- A resin obtained by copolymerizing one or more comonomers such as ethylene chloride monomer and 6-fluorinated propylene. In addition, in the present invention, the reason why the measurement of impact strength for specifying the inner pipe constituent material is limited to test pieces from sheets made by heat pressing is that the heat press method allows easy preparation of test pieces, and the measured values are This is because it can be obtained with a low value. In the present invention, it is preferable to use an interlock metal tube with a plastic tape wrap layer provided on its outer circumferential surface. The reason for this is that the interlocking metal tape of the interlock metal tube has a concave shape, and when the inner tube is directly extruded onto this, the tube material bites into the concave portion.
This is because it is possible to suppress the occurrence of the phenomenon that, depending on the type of material resin or the wall thickness of the inner tube, that part often becomes a source of cracks 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 such as bands, strips, or wires. Furthermore, if the reinforcing layer is composed of short pitch strips with irregular cross-sections and at least two layers of reinforcing strips wound in long pitches with mutually different winding directions, the former reinforcing strips are mainly affected by the internal pressure acting on the pipe. It can serve to withstand circumferential stresses, or the latter can serve to withstand axial stresses due to internal pressures acting on the tube. In addition, if fiber-reinforced plastic strips with a multi-projection cross-section are used as the reinforcing layer material, an appropriate amount of space can be provided between the reinforcing layer strips, resulting in the effect of preventing cooling from the outside. 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-fluoride-1-ethylene chloride monomer at a molar ratio of 9:1 (Izot impact strength of sheet made by hot pressing) is 11.6
A pipe having a wall thickness of 4 mm/mm and an inner diameter of 2 inches was extruded using an apparent Young's modulus of 56.8 kg/mm/mm ² ). Next, add 0.6mm/mm to the outside of the pipe.
Then, two layers of 1 mm/mm thick and 50 mm wide iron strips were wound each with a gap of 5 m/m between adjacent layers, and two layers of 6 m/mm iron wire were wound at a winding angle of 15° so that the winding direction was mutually changed. The tube was wound in different directions, and a 4 mm/mm thick polyethylene was extrusion coated on top of the tube to produce a transport tube. In the above manufacturing process, the polyvinylidene fluoride copolymer resin pipe was wound around a drum with a diameter of 1 m six times in total, but no abnormality occurred. The thus obtained transport pipe maintained an internal pressure rupture property of 500 kg/cm ² . Comparative Example The same size as in Example 1 was prepared using polyvinylidene fluoride obtained by reacting only vinylidene fluoride monomer (Izot impact strength 7.2 Kgcm/cm by hot press sheet method, apparent Young's modulus 88.2 Kg/mm ² ). An attempt was made to make the same transport pipe as in Example 1 by extrusion molding, 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 interlock pipe 1 made of SUS304 using an extruder for 3 m/min. Extrusion coatings were carried out with a thickness of m (see table). This formed tube, that is, the inner tube 3, was bent to a radius of 22 cm, a notch with a length of about 2 cm was made with a knife, and the propagation of cracks was examined. The results are shown in the table. If the crack did not form, the process of stretching it into a straight line and bending it again to a radius of 22 cm was repeated up to 20 times. The results are shown together with the Izod impact test value measured using a 6 mm thick sheet made by hot pressing and the tensile Young's modulus measured using a 1 mm thick sheet. The crack data is shown as the lowest value after testing 5 pieces.

[Table] Regarding the above table, the Izot impact test is based on a 6mm thick sample. Young's modulus is determined from the initial slope of the strain-strength curve obtained by punching out a No. 2 dumbbell from a 1 mm thick sheet and pulling it at 50 mm/min (23°C). Example 5 In Example 2, the interlock tube 1 was made by wrapping multiple layers of polyester tape to a thickness of 0.5 m/m around the 1-inch interlock tube 1.
A plastic tape layer 2 is formed to wrap around the concave part of the interlocking part, and a polyvinylidene fluoride copolymer resin (trade name: Folaclone 650HD, isometric impact strength: 11 Kgcm/cm, apparent Young's modulus: 88 Kg/cm) is formed on top of the plastic tape layer 2.
mm ² ) to a thickness of 3 m/m to obtain a tube, that is, an inner tube 3. When this tube was evaluated in the same manner as in Examples 2 to 4, no cracks occurred up to 20 times. Incidentally, even when the resin of Comparative Example 2 was molded in the same manner, cracks occurred after 6 repetitions. Note that 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 at the biting part. In order to prevent it from getting in, and to provide a certain degree of cushioning by laminating multiple layers,
It is thought that this 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 interlock tube 1 was made 3 inches, and the polyester tape 2 was placed on it to a thickness of 3 inches.
After winding multiple layers so that the thickness is 0.5 mm, the wall thickness is 6.
An inner tube 3 of m/m is provided, and two layers of steel strips 4 having a concave cross-sectional shape (U-shaped strips) are provided on top of the inner tube 3, so that the openings and legs of the tubes interlock with each other. A flat steel strip 5 having a thickness of 3 mm was further 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 thus completed transport pipe, equilibrium was reached and an internal pressure failure test was conducted, resulting in failure at 950 kg/cm ² . In addition,
The surface temperature at this time was 50°C. On the other hand, an attempt was made to manufacture 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 3 used was the same as in Example 3 (see table), and instead of the flat steel strip 4 with a thickness of 3 mm, a tube made of fiber-reinforced plastic with the same cross-sectional area was used. A transport pipe was obtained in the same manner as in Example 6, except that a strip having a cruciform cross section was used. When the same evaluation was performed on this, the internal pressure burst strength was 850 Kg/cm ² . Further, the surface temperature of the tube at this time was 38° C., and it had a higher heat retention property than the tube of Example 6. The effects of the present invention are as follows. In other words, by specially selecting a polyvinylidene fluoride resin with a limited range of properties, which itself has particularly excellent heat resistance, and successfully applying it as an inner tube instead of conventional nylon, we have achieved particularly high heat resistance. A high-temperature fluid transport pipe whose properties can be significantly improved can be provided.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional schematic side view of an embodiment of the present invention. 1... Interlock pipe, 2... Plastic (polyester, etc.) film or tape, 3... Polyvinylidene fluoride copolymer resin, 4... U-shaped strip (steel strip with a concave cross section), 5... Flat strip, 6...Polyethylene.

Claims (1)

[Scope of Claims] 1. A flexible interlocking metal tube formed by molding metal tapes and interlocking with each other, and an outer periphery of the interlocking metal tube for conveying a desired high-temperature, high-pressure fluid inside the tube. A high-temperature fluid transport pipe comprising a coated inner pipe, a reinforcing layer provided on the outside of the inner pipe, and a protective sheath layer covering the outer periphery of the reinforcing layer, wherein the inner pipe is heated by heat pressing. A polyvinylidene fluoride copolymer resin, or a blend of a polyvinylidene fluoride resin and the copolymer resin, in which the produced sheet has an Izot impact strength of 10 Kgcm/cm or more and an apparent Young's modulus of 90 Kg/mm ² or less. 1. A high-temperature fluid transport pipe, characterized in that the pipe is extrusion-molded using either a polyvinylidene fluoride copolymer resin or a composition based on the polyvinylidene fluoride copolymer resin. 2. The high-temperature fluid transport pipe according to claim 1, wherein the reinforcing layer provided on the outside of the inner pipe is constructed by winding reinforcing strips made of metal or fiber-reinforced plastic. 3. A patent characterized in that the reinforcing layer is composed of a reinforcing strip having an irregular cross-sectional shape, which is wound in short pitches, and a reinforcing strip, which is wound in long pitches 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 wound in long pitches have a multi-projection cross section. transport pipes for high-temperature fluids.