Liquid delivery pipe

Abstract

To provide a liquid transport pipe acting on inner pressure and external pressure simultaneously.SOLUTION: A liquid transport pipe 10 made of a thermoplastic resin comprises a pipe-shaped internal pressure-resistant part 14 having a pipe thickness required against internal pressure of liquid to be transported, and an external pressure-resistant part 15 required against external pressure. The external pressure-resistant part 15 is spirally provided on the outer periphery of the internal pressure-resistant part 14, and is formed by a rib 15a having a hollow part inside.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a liquid transport pipe made of a thermoplastic resin.

Background Art

[0002] JIS K 6780 defines a pressure-resistant polyethylene ribbed pipe. The pressure-resistant polyethylene ribbed pipe is an external pressure pipe made of high-density polyethylene with ribs. This type of pressure-resistant polyethylene ribbed pipe is an external pressure pipe used by being buried in the ground (see Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in fields such as pipelines for transporting agricultural water that distribute agricultural water by a pressure pipeline formed by burying ready-made pipes, a liquid transport pipe in which external pressure and internal pressure act simultaneously is desired.

Means for Solving the Problems

[0005] The liquid transport pipe for solving the above problems is a liquid transport pipe made of a thermoplastic resin, and includes a pipe-shaped internal pressure-resistant part having a strength capable of withstanding the internal pressure of the transported liquid, and an external pressure-resistant part having a strength capable of withstanding external pressure. The external pressure-resistant part is formed by ribs that are provided spirally on the outer circumference of the internal pressure-resistant part and have a hollow part inside.

[0006] According to the above configuration, the internal pressure resistant part has a strength capable of withstanding the internal pressure, and the external pressure resistant part has a strength capable of withstanding the external pressure. And the external pressure resistant part is composed of ribs having a hollow part. The liquid transport pipe can be lightened by configuring the external pressure resistant part with ribs while having a strength capable of withstanding the internal and external pressures.

[0007] In the above liquid transport pipe, at least the internal pressure resistant part of the internal pressure resistant part and the external pressure resistant part may be composed of a molded body of a thermoplastic resin containing glass fiber. According to the above configuration, at least the internal pressure resistant part of the internal pressure resistant part and the external pressure resistant part is molded with a thermoplastic resin containing glass fiber, so that the wall thickness of the internal pressure resistant part can be thinned.

[0008] In the above liquid transport pipe, it is preferable that the wall thickness of the internal pressure resistant part is 15 mm or more. According to the above configuration, by having a wall thickness of 15 mm or more for the internal pressure resistant part, the strength against the internal pressure can be increased, and the strength required for use can be realized.

[0009] In the above liquid transport pipe, it is preferable that the pitch of the ribs is 60 mm to 180 mm. According to the above configuration, the strength against the external pressure required for use can be realized while lightening the weight.

[0010] In the above liquid transport pipe, it is preferable that the inner diameter of the internal pressure resistant part is 600 mm to 1500 mm. According to the above configuration, it can be applied to a liquid transport pipeline such as a pipeline for transporting agricultural water.

[0011] In the above liquid transport pipe, as an example, the liquid transport pipe is used for a pipeline for transporting agricultural water.

Effect of the Invention

[0012] According to the present invention, a liquid transport pipe on which internal pressure and external pressure act simultaneously can be provided.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

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Figure 8

Figure 9

Mode for Carrying Out the Invention

[0014] Hereinafter, the liquid transport pipe to which the present invention is applied will be described with reference to the drawings. 〔Configuration of Liquid Transport Pipe〕 As shown in FIG. 1, this liquid transport pipe 10 constitutes a liquid transport pipeline 1 such as a pressure pipeline formed by embedding a ready-made pipe, and is used in fields such as a pipeline for agricultural water transport for supplying and distributing agricultural water. The liquid transport pipe 10 is a buried pipe in which internal pressure and external pressure acting simultaneously are applied while being buried in the ground 2.

[0015] The liquid transport pipe 10 includes a pipe body part 11, a receiving part 12 formed on the first pipe end side in the pipe axis direction, and an insertion part 13 formed on the second end side opposite to the first end. Further, the pipe body part 11 includes, in the thickness direction, an internal pressure resistant part 14 and an external pressure resistant part 15. The internal pressure resistant part 14 is an internal pressure pipe configured to have a strength capable of withstanding the force due to the internal pressure (for example, internal water pressure) of the liquid flowing inside. Further, the external pressure resistant part 15 is constituted by ribs 15a spirally provided on the outer periphery of the internal pressure resistant part 14 so as to be able to withstand the force due to external pressure such as earth pressure and vehicle load.

[0016] The internal pressure resistant part 14, the receiving port part 12, and the insertion port part 13 are molded bodies of the same thermoplastic resin. In this embodiment, they are molded tubes of a thermoplastic resin containing glass fibers. Such a molded tube can be made into a tube excellent in chemical resistance, corrosion resistance, abrasion resistance, impact resistance, and light weight by using, for example, a high-density polyethylene material as the plastic resin. Furthermore, by controlling the orientation and orientation of the glass fibers, it becomes a tube with high rigidity in the circumferential direction of the tube. The glass fibers are oriented in the circumferential direction of the tube.

[0017] The addition amount of the glass fibers is 10% - 30%, preferably 19% - 21%, and more preferably about 20%. Also, as the glass fibers, short fiber glass with a diameter of 10 μm - 15 μm and a length of about 2 mm - 5 mm is used. The density of the internal pressure resistant part 14 is, as an example, 1020 kg / m 3 ~1120 kg / m 3 is.

[0018] As shown in FIG. 2, the wall thickness t of the internal pressure resistant part 14 is, as an example, 15 mm or more. Also, the wall thickness t of the internal pressure resistant part 14 is, as an example, 60 mm or less. The wall thickness t of the internal pressure resistant part 14 increases as the inner diameter increases. As an example, when the inner diameter is 600 mm, the wall thickness t of the internal pressure resistant part 14 is 15 mm. Also, as an example, when the inner diameter is 1500 mm, the wall thickness t of the internal pressure resistant part 14 is 59 mm. In an external pressure tube such as a pressure-resistant polyethylene rib tube where the internal pressure is not considered, the thickness of the base part corresponding to the internal pressure resistant part 14 is about 6 mm. The wall thickness t of the internal pressure resistant part 14 is configured to be thicker than the thickness of the base part of an external pressure tube such as a pressure-resistant polyethylene rib tube in consideration of the internal pressure.

[0019] The external pressure resistant part 15 is a thermoplastic resin that does not contain glass fibers. In this embodiment, a high-density polyethylene material is used. The external pressure resistant part 15 is a rib 15a provided spirally on the outer circumference of the internal pressure resistant part 14. That is, since the external pressure resistant part 15 directly contacts the earth and sand and only needs to withstand the external pressure from the earth and sand, it does not necessarily need to have a tube shape for realizing water tightness.

[0020] The rib 15a has a rectangular cross-sectional shape and includes a hollow portion 15b having a circular cross-sectional shape inside. As an example, one side of the rib 15a is 60 mm. Also, in the rib 15a, the diameter of the hollow portion 15b is 50 mm. Further, the pitch p of the rib 15a wound spirally around the internal pressure-resistant portion 14 increases in strength against external pressure as it gets smaller and decreases as it gets larger. As an example, it is 60 mm to 180 mm.

[0021] As shown in FIG. 3, the receiving portion 12 is configured such that its outer diameter and inner diameter are larger than those of the pipe main body portion 11. The inner surface of the receiving portion 12 is a surface facing the outer surface of the insertion portion 13. The inner surface of the receiving portion 12 is provided with a heating element portion 16. The heating element portion 16 is, for example, a heating resistor. The heating element portion 16 may be configured as a series of heating resistors having a width of 60 mm as an example, or may be configured in two series. The heating element portion 16 is fixed to the inner surface of the receiving portion 12. The heating element portion 16 is connected to a control device via a heating wire terminal 16a and generates heat under the set energization conditions.

[0022] The insertion portion 13 has an inner diameter that matches the inner diameter of the pipe main body portion 11, an outer diameter that is larger than that of the pipe main body portion 11, and is composed of a thick-walled portion. The inner surface of the insertion portion 13 is flush with the inner surface of the pipe main body portion 11, and the outer surface of the insertion portion 13 is a surface facing the receiving portion 12.

[0023] 〔Manufacturing method of the liquid transport pipe〕 The internal pressure-resistant portion 14 is manufactured by winding extrusion molding. Specifically, when a thermoplastic resin material containing molten glass fibers is extruded from an extruder, the sheet-like resin extruded in a band shape has the glass fibers arranged in the longitudinal direction. Then, such a sheet-like resin is spirally wound around a mandrel, which is a mold having a cylindrical shape, in multiple layers. Thereby, the internal pressure-resistant portion 14, the receiving portion 12, and the insertion portion 13 are manufactured.

[0024] Next, on the outer periphery of the formed pipe body portion 11, a molten resin for ribs for forming ribs 15a is spirally wound at a predetermined pitch p, and thus is fused to the outer peripheral surface of the pipe body portion 11. The heating element portion 16 is fixed to the inner surface of the receiving portion 12 by a fixture such as a tacker.

[0025] 〔Connection of Liquid Transport Pipe〕 The ground is excavated to lay the liquid transport pipeline 1, and the liquid transport pipe 10 is sequentially arranged in the excavated embedding groove. Then, the insertion portion 13 is inserted into the receiving portion 12, and the adjacent liquid transport pipes 10 are sequentially connected. The joint portion is connected by an electric fusion joint structure. Specifically, the joint portion is centered and temporarily fixed, and further fixed by a fixture such as a sling belt. Next, a control device is connected to the heating wire terminal 16a of the heating element portion 16 facing outward. The control device causes the heating element portion 16 to generate heat for a predetermined time under the set energization conditions. As a result, the receiving portion 12 and the insertion portion 13 are melted. The receiving portion 12 and the insertion portion 13 are then solidified by being cooled for a predetermined time, and the two are integrated. Then, by sequentially connecting the liquid transport pipes 10, the liquid transport pipeline 1 can be configured. After this, the embedding groove is backfilled. Incidentally, in the liquid transport pipe 10 configured as described above, the allowable water pressure is, for example, 0.5 MPa.

[0026] 〔Pitch of Rib〕 The pitch p of the ribs 15a is the distance between the centers O of the hollow portions 15b of the ribs 15a adjacent to each other. The smaller the pitch p of the ribs 15a, the higher the strength of the external pressure resistant portion 15 against external pressure, and the larger the pitch p, the weaker the strength. Here, each side of the rib 15a is 60 mm.

[0027] FIG. 4 shows an example where the pitch p of the rib 15a is 90 mm, FIG. 5 shows an example where the pitch p is 150 mm, and FIG. 6 shows an example where the pitch p is 180 mm. In the examples of FIGS. 4 to 6, the outer peripheral surface of the internal pressure resistant portion 14 is exposed between the ribs 15a. On the other hand, FIG. 7 shows an example where the pitch p is 60 mm. In this case, since one side of the rib 15a has the same pitch, the internal pressure resistant portion 14 is no longer exposed between the adjacent ribs 15a. That is, the external pressure resistant portion 15 is composed of a continuous surface on its outer peripheral surface.

[0028] Further, FIG. 8 shows a structure in which two stages of ribs 15a with a pitch p of 60 mm are provided and the height is H1. Furthermore, FIG. 9 shows a structure in which two stages of ribs 15a with a pitch p of 60 mm are provided, and further ribs 15c with a pitch p1 larger than 60 mm are provided on the surface thereof, and the height is H2.

[0029] 〔Effects of the Embodiment〕 The liquid transport pipe 10 as described above can obtain the following effects. (1) The liquid transport pipe 10 has a strength such that the internal pressure resistant portion 14 can withstand internal pressure, and the external pressure resistant portion 15 has a strength such that it can withstand external pressure. And the external pressure resistant portion 15 is composed of ribs 15a and 15c having a hollow portion 15b.

[0030] Therefore, it is possible to reduce the weight of the liquid transport pipe having a strength capable of withstanding internal and external pressures as compared with a pipe formed of a solid thermoplastic resin without providing the ribs 15a. In addition, since the liquid transport pipeline 1 is easily bent, it can also be laid in peat, soft ground, etc.

[0031] (2) The internal pressure resistant portion 14 has high strength by using a thermoplastic resin containing glass fibers, and can be made thinner. That is, a liquid transport pipe in which the internal pressure resistant portion 14 is formed of high-density polyethylene containing glass fibers can make the internal pressure resistant portion 14 thinner and thus lighter in weight than when glass fibers are not contained in the high-density polyethylene in the internal pressure resistant portion 14.

[0032] (3) The internal pressure resistant part 14 has a pipe thickness of, for example, 15 mm or more, which increases the strength against internal pressure and can achieve the strength required in use. And since there is no need to consider external pressure for the internal pressure resistant part 14, it can be made thinner than when considering external pressure.

[0033] (4) The pitch p of the rib 15a is 60 mm to 180 mm, which can achieve the strength against external pressure required in use while reducing the weight. (5) Since the inner diameter of the liquid transport pipe 10 is 600 mm to 1500 mm, it can be applied to a liquid transport pipeline 1 such as a pipeline for agricultural water transport.

[0034] 〔Modification example〕 In addition, the liquid transport pipeline 1 as described above can also be implemented by appropriately changing as follows.

[0035] · The liquid transport pipeline 1 is not limited to a pipeline for agricultural water transport, and may be applied to a water pressure pipeline of a hydroelectric power facility, a water treatment facility, a sewer facility, an in-plant circulating water pipe, etc. · The rib 15a is not limited to having a rectangular cross-sectional shape and including a hollow part 15b inside. For example, the cross-sectional shape may be circular or elliptical, and the hollow part 15b may also be circular or elliptical. Also, the thickness of the rib 15a may be configured such that one side is less than 60 mm and the diameter of the hollow part 15b is less than 50 mm. According to such a configuration, the pitch p of the rib 15a can be set more finely.

[0036] · The inner diameter of the internal pressure resistant part 14 may be designed to be less than 600 mm, or may be set to be larger than 1500 mm. · The pipe thickness t of the internal pressure resistant part 14 may be less than 15 mm. For example, if a resin with higher strength is used to form the internal pressure resistant part 14, it can be made thinner.

[0037] · For the rib 15a, a thermoplastic resin containing glass fibers, for example, a high-density polyethylene material containing glass fibers, may also be used. In this case, in the rib 15a as well, a state where the glass fibers are arranged in the longitudinal direction is preferable. Also, the internal pressure resistant part 14, the receiving part 12, and the inserting part 13 may be molded from a thermoplastic resin that does not contain glass fibers. That is, the liquid transport pipe 10 may be molded using a thermoplastic resin that does not contain glass fibers for the internal pressure resistant part 14, the receiving part 12, the inserting part 13, and the rib 15a, or may be molded using a thermoplastic resin containing glass fibers. The wall thickness of the internal pressure resistant part 14 becomes thinner in the case of a thermoplastic resin containing glass fibers because of its high strength, and becomes thicker in the case of a thermoplastic resin that does not contain glass fibers.

[0038] · The joint structure is not limited to an electric fusion joint structure. It may be a butt fusion joint structure, a flange joint structure, or the like. · As the thermoplastic resin, in addition to high-density polyethylene, polypropylene (PP), polyvinyl chloride (PVC), ABS resin (acrylonitrile-butadiene-styrene resin), AS resin, acrylic resin (PMMA), etc. may also be used.

[0039] · The material of the liquid transport pipe 10 may include a pipe, a joint, and additives such as pigments, antioxidants, stabilizers, etc. that are necessary for its use. Also, the material of the liquid transport pipe 10 may include a coupling material.

[0040] · The liquid to be transported may be seawater, sewage, etc. in addition to pure water, or may be a chemical solution, etc. · The liquid transport pipeline 1 may be applied to a liquid transport pipe in deep underground. Deep underground means a depth where it is not usually used for the construction of a basement (more than 40 m deep underground), or a depth where it is not usually used for the installation of a building foundation (more than 10 m deep from the upper surface of the supporting ground).

Explanation of Reference Numerals

[0041] 1... Liquid transport pipeline 2... Subterranean 10... Liquid transport pipe 11… Pipe body part 12… Receiving port part 13… Outlet part 14… Inner pressure resistant part 15… Outer pressure resistant part 15a… Rib 15b… Hollow part 15c… Rib 16… Heating element part 16a… Heating wire terminal

Claims

1. A liquid transport pipe made of a thermoplastic resin buried in the ground, comprising: a pipe-shaped internal pressure resistant part having a strength capable of withstanding the internal pressure of the liquid to be transported; an external pressure resistant part having a strength capable of withstanding external pressure; the external pressure resistant part is provided spirally on the outer periphery of the internal pressure resistant part and is composed of ribs having a hollow part inside; the internal pressure resistant part is a molded body of the thermoplastic resin containing glass fibers arranged in the longitudinal direction; the external pressure resistant part is formed by molding the thermoplastic resin not containing glass fibers; the density of the internal pressure resistant part is 1020 kg / m3 to 1120 kg / m3 Liquid transport pipe.

2. The external pressure resistant part has a rectangular cross-sectional shape and has a hollow part with a circular cross-sectional shape inside, and is formed by spirally winding molten resin for ribs around the internal pressure resistant part. The liquid transport pipe according to Claim 1.

3. The wall thickness of the internal pressure resistant part is 15 mm or more. The liquid transport pipe according to Claim 1 or 2.

4. The pitch of the ribs is 60 mm to 180 mm. The liquid transport pipe according to any one of Claims 1 to 3.

5. The inner diameter of the internal pressure resistant part is 600 mm to 1500 mm. The liquid transport pipe according to any one of Claims 1 to 4.

6. The liquid transport pipe is used for a pipeline for transporting agricultural water. The liquid transport pipe according to any one of Claims 1 to 5.

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