JP7028686B2 - Method for manufacturing flexible tube for fluid transportation and flexible tube for fluid transportation - Google Patents

Description

The present invention relates to a fluid transport flexible tube and a method for manufacturing a fluid transport flexible tube used when transporting a fluid such as liquefied natural gas (LNG) having an extremely low temperature.

Conventionally, when a fluid such as liquefied natural gas, which is extremely low temperature, is transported from an offshore floating facility at sea to a tanker, a reinforcing layer, a heat insulating layer, and a waterproof layer are provided on the outer periphery of a flexible inner pipe, which is a pole. A flexible tube having both durability and heat insulating properties that can be used even at low temperatures is used (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2009-2435118

FIG. 4 is a diagram showing a process of manufacturing a conventional flexible tube 100. The flexible pipe 100 is provided on the inner pipe 101, the reinforcing layer 103 provided on the outer peripheral portion of the inner pipe 101, the heat insulating layer 105 provided on the outer peripheral portion of the reinforcing layer 103, and the outer peripheral portion of the heat insulating layer 105. It is composed of a protective layer 107.

The inner tube 101 is, for example, a metal wavy flexible tube. The reinforcing layer 103 is formed by winding a tape made of stainless steel or aramid to reinforce the axial force of the flexible pipe 100. The heat insulating layer 105 provided on the outer peripheral portion of the reinforcing layer 103 is provided so that the fluid in the inner pipe 101 is not affected by the outside temperature, and the protective layer 107 provided on the outer peripheral portion of the heat insulating layer 105 is set to the temperature of the fluid. The fluid inside the inner pipe 101 and the outside are insulated so as not to be affected. The protective layer 107 is made of resin, for example, and can be deformed following the inner tube 101.

The protective layer 107 is formed by injecting a heated resin between the base 109a and the base 109b (arrow D in the figure), extruding the protective layer 107 to the outer periphery of the heat insulating layer 105, and then cooling the protective layer 107. Here, for the heat insulating layer 105, for example, a foamed resin, airgel, or the like is used. Therefore, the heat insulating layer 105 has a relatively low compressive elastic modulus.

Therefore, as shown in FIG. 4, when the resin is extruded to the outer periphery of the heat insulating layer 105, the heat insulating layer is easily deformed locally due to the pressure of the resin. For example, as shown in the figure, when the heat insulating layer 105 is crushed, a gap is created between the protective layer 107 and the base 109a, and the thickness and shape of the protective layer 107 are not stable. It causes a defect.

Further, FIG. 5A is a view showing a state in which the flexible tube 100 is bent, and FIG. 5B is an enlarged view of a cross section in the vicinity of the range F shown in FIG. 5A. As shown in FIG. 5A, when the flexible tube 100 is greatly bent in the direction indicated by the arrow E, the heat insulating layer 105 is deformed together with the protective layer 107 as shown in FIG. 5B, and inside the bending. Wrinkles 113 are likely to occur.

Not only does such a wrinkle 113 have a poor appearance, but the heat insulating effect of the heat insulating layer 105 becomes different from that of the surroundings. As a result, a temperature distribution is formed in the protective layer 107, thermal stress is generated, and the protective layer 107 may develop into cracks due to repeated use.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a fluid transport flexible tube and a method for manufacturing a fluid transport flexible tube, which are less likely to cause poor appearance.

In order to achieve the above-mentioned object, the first invention comprises a flexible inner pipe, a reinforcing layer provided on the outer periphery of the inner pipe, a heat insulating layer provided on the outer periphery of the reinforcing layer, and the above-mentioned. A cushioning layer provided on the outer periphery of the heat insulating layer and a protective layer provided on the outermost peripheral portion are provided, and the compressive elastic modulus of the cushioning layer is smaller than the compressive elastic modulus of the heat insulating layer, and the heat insulating layer is provided. It is a flexible tube for fluid transport, characterized in that the crushing allowance of the cushioning layer is smaller due to the crushed state of the cushioning layer than the layer .

It is desirable that the softening temperature of the buffer layer is lower than the softening temperature of the protective layer.
It is also desirable that the thickness of the cushioning layer is thinner than the thickness of the heat insulating layer.

According to the first invention, by providing a buffer layer between the protective layer and the heat insulating layer, the buffer layer absorbs the deformation of the heat insulating layer and the like, and suppresses the deformation of the protective layer due to the deformation of the heat insulating layer. can. In particular, since the compressive elastic modulus of the cushioning layer is smaller than the compressive elastic modulus of the heat insulating layer, deformation of the heat insulating layer can be suppressed. At this time, since the cushioning layer does not require a heat insulating effect, the thickness can be reduced, and even if a cushioning layer having a low compressive elastic modulus is used, the amount of deformation of the protective layer can be suppressed.

Further, if the softening temperature of the buffer layer is lower than the softening temperature of the protective layer, the buffer layer can be softened at the time of extrusion coating of the protective layer, and the buffer layer and the protective layer can be brought into close contact with each other. Therefore, a gap is unlikely to occur between the buffer layer and the protective layer, and the occurrence of wrinkles can be suppressed. Further, since the heat insulating layer does not have a fused portion, the heat insulating property is not affected.

The second invention comprises a step of forming a reinforcing layer on the outer periphery of the inner pipe, a step of winding a heat insulating member around the outer periphery of the reinforcing layer to form a heat insulating layer, and a step of forming a cushioning member on the outer periphery of the heat insulating layer. A step of winding to form a buffer layer and a step of extruding a protective layer on the outer periphery of the cushion layer are provided, and the compressive elastic modulus of the buffer layer is smaller than the compressive elastic modulus of the heat insulating layer. Further, it is a method for manufacturing a flexible tube for fluid transport, characterized in that the crushing allowance of the cushioning layer is reduced due to the crushed state of the cushioning layer as compared with the heat insulating layer .

It is desirable that the outer diameter of the cushion layer wrapped around the protective layer is larger than the diameter of the base when the protective layer is extruded and coated, and the protective layer is extruded and coated while the cushioning layer is compressed by the base.

According to the second invention, it is possible to efficiently manufacture a flexible tube for fluid transport by suppressing the occurrence of vertical wrinkles and the like.

At this time, by making the outer diameter in the state where the buffer layer is wound larger than the diameter of the base when the protective layer is extruded and covered, the protective layer can be extruded while compressing the buffer layer with the base. By doing so, it is possible to suppress the deformation of the cushioning layer when the protective layer is extruded.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a flexible tube for fluid transportation and a method for manufacturing a flexible tube for fluid transportation, which are less likely to cause poor appearance.

The perspective view which shows the structure of a flexible tube 1. Partial sectional view of flexible tube 1. The figure which shows the manufacturing process of a flexible tube 1. The figure which shows the manufacturing process of the conventional flexible tube 100. (A) is a view showing a state in which a conventional flexible tube 100 is bent, and (b) is an enlarged sectional view of a portion F of (a).

Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is a perspective view of the flexible tube 1 according to the first embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of the flexible tube 1 in the axial direction. The flexible tube 1 capable of transporting a low-temperature fluid such as LNG is mainly composed of an inner tube 3, a reinforcing layer 7, a heat insulating layer 9, a buffer layer 11, a protective layer 13, and the like.

A fluid (hereinafter, will be described as LNG flowing) flows inside the inner pipe 3. The inner tube 3 is a flexible tube, and it is desirable that the inner tube 3 is excellent in strength and low temperature resistance to some extent. That is, a material that can maintain flexibility even when a cryogenic fluid such as LNG is flowed inside the inner pipe 3 and is less likely to cause cracks or cracks is preferable. The inner tube 3 is made of metal, for example, and preferably a stainless steel corrugated tube can be used.

A reinforcing layer 7 is provided on the outer peripheral portion of the inner pipe 3. The reinforcing layer 7 mainly suppresses the deformation (stretching) of the inner pipe 3 in the axial direction, and is deformable following the flexibility of the inner pipe 3. The reinforcing layer 7 is formed of, for example, a reinforcing tape such as a fiber tape or a metal tape, or a woven structure of fibers or metal strands.

The reinforcing layer 7 is located inside the heat insulating layer 9, and when a cryogenic fluid such as LNG is flowed inside the inner pipe 3, it is cooled to a temperature close to that of a cryogenic fluid such as LNG. Therefore, it is desirable that the material maintains high strength even at extremely low temperatures and has excellent low temperature characteristics without embrittlement.

Further, if necessary, a seat floor layer 5 (not shown in FIG. 2) made of a non-woven fabric or the like is provided on the outer peripheral portion of the inner pipe 3. The seat floor layer 5 is a layer for flattening the uneven shape on the outer periphery of the inner pipe 3, and is deformable following the flexibility of the inner pipe 3. That is, the seat floor layer has a certain thickness and has a role as a cushion having an uneven shape.

A heat insulating layer 9 is provided on the outer periphery of the reinforcing layer 7. The heat insulating layer 9 insulates the LNG flowing inside the inner pipe 3 and the outside of the flexible pipe 1, and is deformable following the flexibility of the inner pipe 3. As the heat insulating layer 9, for example, a blanket-like heat insulating material such as glass fiber, ceramic fiber, or rock wool, or a plastic in which a filler material such as aerogel, foamed plastic, or glass beads is dispersed is used.

Airgel is a substance produced in the form of a gel by replacing water with gas, and contains air of about 90% or more of the volume, is extremely light, and has high heat insulating properties. Airgel is produced, for example, containing silica, alumina or the like as a main component. The heat insulating layer 9 is formed, for example, by impregnating a polyester non-woven fabric with airgel. The thickness of the heat insulating layer 9 is, for example, 10 mm to 50 mm.

A cushioning layer 11 is provided on the outer periphery of the heat insulating layer 9. The compressive elastic modulus of the cushioning layer 11 is smaller than the compressive elastic modulus of the heat insulating layer 9. That is, the cushioning layer 11 is softer than the heat insulating layer 9. For example, the compressive elastic modulus of the cushioning layer 11 may be about ½ or less and 1/10 or more of the compressive elastic modulus of the heat insulating layer 9. If the compressive elastic modulus of the cushioning layer 11 is too large, the amount of compression of the heat insulating layer 9 becomes large, and it is not possible to suppress the thickness variation of the heat insulating layer 9. On the other hand, if the compressive elastic modulus of the cushioning layer 11 is too small, the protective layer 13 is crushed too much when extruded, and the amount of compression of the heat insulating layer 9 becomes large, so that the thickness variation of the heat insulating layer 9 cannot be suppressed.

Further, the thickness of the cushioning layer 11 is thinner than the thickness of the heat insulating layer 9. The thickness of the cushioning layer 11 may be thick enough to absorb the variation in the thickness of the heat insulating layer 9. For example, the thickness of the cushioning layer 11 may be about 1/3 to 1/10 of the thickness of the heat insulating layer 9. If the thickness of the cushioning layer 11 is too thin, the variation in the thickness of the heat insulating layer 9 cannot be completely absorbed. On the other hand, if the thickness of the buffer layer 11 is too thick, the thickness variation of the buffer layer 11 becomes large. The thickness of the cushioning layer 11 is preferably 5 mm or more.
For the cushioning layer, the same material as the heat insulating layer, for example, a blanket-like heat insulating material or foamed plastic can be used. It is desirable that the melting point of the buffer layer is lower than the extrusion molding temperature of the protective layer.

A protective layer 13 is provided on the outer periphery of the cushioning layer 11. That is, the protective layer 13 is formed on the outermost peripheral portion of the flexible tube 1. A pressing tape may be wrapped around the outer periphery of the cushioning layer 11 in advance. The protective layer 13 is deformable following the flexibility of the inner tube 3 while preventing the ingress of water from the outside. It is desirable that the softening temperature of the buffer layer 11 is lower than the softening temperature of the protective layer 13. For example, it is desirable that the softening temperature of the buffer layer 11 is 5 ° C. or higher lower than the softening temperature of the protective layer 13. By doing so, the protective layer 13 and the cushioning layer 11 can be integrated at the time of extrusion molding of the protective layer 13. Further, since the extrusion molding temperature of the protective layer 13 is about 150 ° C. to 250 ° C., if the softening point of the buffer layer 11 is lower than the extrusion molding temperature, the protective layer 13 and the buffer layer 11 should be more firmly integrated. Can be done. The softening point of each layer is measured based on JIS K7206.

The flexible tube 1 is not limited to the above configuration. It may have other functional layers, or may have other configurations in the flexible tube 1.

Next, a method for manufacturing the flexible tube 1 will be described. First, a reinforcing tape is wrapped around the outer circumference of the inner pipe 3 to form the reinforcing layer 7. As described above, the reinforcing layer 7 may be formed after the seat floor layer 5 is formed on the outer periphery of the inner pipe 3.

Next, the heat insulating layer 9 is formed on the outer periphery of the reinforcing layer 7. The heat insulating layer 9 is formed by, for example, a tape-shaped heat insulating member being spirally wound (butt-wound) without a gap by abutting the ends in the width direction. In addition, in order to secure a predetermined heat insulating performance, the heat insulating layer 9 may have a thickness secured by laminating and winding a tape-shaped heat insulating member in a plurality of layers.

Next, the cushioning layer 11 is formed on the outer periphery of the heat insulating layer 9. The cushioning layer 11 is formed by vertically wrapping or spirally winding the cushioning member so that the ends are abutted against each other. The cushioning layer 11 is formed so as to cover the entire outer circumference of the heat insulating layer 9.

Further, the protective layer 13 is extruded and coated (for example, pressure extrusion) on the outer periphery of the cushioning layer 11. FIG. 3 is a diagram showing a state in which the protective layer 13 is extruded and covered. The heated resin constituting the protective layer 13 is injected between the caps 17a and 17b (A in the figure), and the resin is extruded to the outer periphery of the buffer layer 11 on the tip side of the caps 17a and 17b.

At this time, the outer diameter of the cushioning layer 11 (C in the figure) before the extruded coating of the protective layer 13 is larger than the inner diameter of the base 17a (B in the figure) when the protective layer 13 is extruded and coated. Therefore, the cushioning layer 11 is sent to the tips of the caps 17a and 17b while being compressed by the cap 17b, and the protective layer 13 is extruded and covered. As described above, the compressive elastic modulus of the cushioning layer 11 is smaller than the compressive elastic modulus of the heat insulating layer 9. Therefore, when the buffer layer 11 is compressed, the buffer layer 11 is preferentially crushed over the heat insulating layer 9.

When the protective layer 13 is extruded and covered on the outer periphery of the cushioning layer 11 in this state, the cushioning layer 11 has less crushing allowance, so that appearance defects such as vertical wrinkles after extruding the protective layer 13 are suppressed. To. Further, since the change in the thickness of the heat insulating layer 9 is suppressed, it is possible to suppress the variation in the heat insulating effect depending on the portion.

As described above, according to the flexible tube 1 according to the present embodiment, the cushioning layer 11 can suppress the collapse of the heat insulating layer 9. Therefore, it is possible to suppress variations in the heat insulating property depending on the portion of the heat insulating layer 9.

Further, by feeding the protective layer 13 while crushing it when the protective layer 13 is extruded, the buffer layer 11 can suppress further crushing of the buffer layer 11 due to the extrusion pressure of the protective layer 13. Therefore, when the protective layer 13 is extruded, it is possible to suppress the formation of a gap between the protective layer 13 and the base 17a, and it is possible to suppress the occurrence of vertical wrinkles in the protective layer 13.

Further, since the softening temperature of the buffer layer 11 is lower than the extrusion temperature of the protective layer 13, the buffer layer 11 and the protective layer 13 can be fused at the time of extrusion. Therefore, no gap is formed between the protective layer 13 and the cushioning layer 11, and wrinkles are less likely to occur during bending. At this time, since the fused layer is not formed on the heat insulating layer 9, it is possible to suppress the deterioration of the heat insulating property.

Flexible tubes with and without a cushioning layer were prepared, and the appearance and bending wrinkle condition after extrusion molding were evaluated.

The size of the inner tube was 6 inches. The material of the heat insulating layer was airgel having a compressive elastic modulus of 172 kPa (ASTM C165). The heat insulating layer was formed by stacking three layers of tape-shaped members having a thickness of 10 mm and butt-wrapping them. That is, the thickness of the heat insulating layer was set to 30 mm.

A buffer layer was formed on the outer periphery of the heat insulating layer. The buffer layer was made of foamed cross-linked polyethylene having a foaming ratio of 30 times. The compressive elastic modulus of the buffer layer was 46 kPa (ASTM C165). A tape-shaped member having a thickness of 5 mm was vertically attached to form a cushioning layer.

The protective layer was made of EP rubber. The thickness of the protective layer was 10 mm, and the outer diameter of the protective layer was 273 mm. As a comparative example, a flexible tube without only the buffer layer was prepared.

The flexible tube provided with the buffer layer suppressed the occurrence of vertical wrinkles during molding as compared with the flexible tube provided with no buffer layer. It is considered that this is because when the protective layer was extruded and coated, the cushioning layer was crushed and extruded, so that no gap was formed between the protective layer and the base, and the occurrence of vertical wrinkles was suppressed. Be done.

Further, when the flexible tube without the buffer layer is bent, wrinkles are generated inside the bend, but the occurrence of these wrinkles is suppressed in the flexible tube provided with the buffer layer. As described above, by providing a cushioning layer, it was possible to obtain a flexible tube that is less likely to cause poor appearance.

Although the embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention does not depend on the above-described embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

For example, a cushioning layer is provided for a flexible tube for transporting a low-temperature fluid, but it can also be applied to hoses and cables for other purposes. For example, it can be applied as long as a protective layer is formed on the outermost periphery and a layer having a relatively low compressive elastic modulus such as a heat insulating layer is formed inside the protective layer.

1 ………… Flexible pipe 3 ………… Inner pipe 5 ………… Seat floor layer 7 ………… Reinforcing layer 9 ………… Insulation layer 11 ………… Buffer layer 13 ………… Protective layers 17a, 17b ………… Mouthpiece 100 ………… Flexible pipe 101 ………… Inner pipe 103 ………… Reinforcing layer 105 ………… Insulation layer 107 ………… Protective layers 109a, 109b ………… Mouthpiece 113 ………… Wrinkles

Claims (5)

Flexible inner tube and
A reinforcing layer provided on the outer circumference of the inner pipe and
A heat insulating layer provided on the outer periphery of the reinforcing layer and
A cushioning layer provided on the outer periphery of the heat insulating layer and
The protective layer provided on the outermost circumference and
Equipped with
The compressive elastic modulus of the cushioning layer is smaller than the compressive elastic modulus of the heat insulating layer.
A flexible tube for fluid transport, characterized in that the crushing allowance of the cushioning layer is smaller due to the crushed state of the cushioning layer than that of the heat insulating layer . The flexible tube for fluid transport according to claim 1, wherein the softening temperature of the buffer layer is lower than the softening temperature of the protective layer. The flexible tube for fluid transport according to claim 1 or 2, wherein the thickness of the cushioning layer is thinner than the thickness of the heat insulating layer. The process of forming a reinforcing layer on the outer circumference of the inner pipe,
A step of winding a heat insulating member around the outer periphery of the reinforcing layer to form a heat insulating layer,
A step of winding a cushioning member around the outer periphery of the heat insulating layer to form a cushioning layer,
A step of extruding and covering the outer periphery of the cushioning layer with a protective layer,
Equipped with
The compressive elastic modulus of the cushioning layer is smaller than the compressive elastic modulus of the heat insulating layer.
A method for manufacturing a flexible tube for fluid transport, characterized in that the crushing allowance of the cushioning layer is reduced due to a state in which the cushioning layer is crushed more than the heat insulating layer . The outer diameter of the cushioning layer before the extruded coating of the protective layer is larger than the diameter of the base when the protective layer is extruded and coated, and the protective layer is extruded and covered while the cushioning layer is compressed by the base. The method for manufacturing a flexible tube for fluid transportation according to claim 4 .

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