JP2022154030A - Liquid transport pipe and manufacturing method for liquid transport pipe - Google Patents

Abstract

To provide a liquid transport pipe capable of increasing an inner diameter of the liquid transport pipe inserted into an existing pipe.SOLUTION: A water transport pipe to be inserted into an existing pipe, comprises a pipe body 11 configured as a compact of a thermoplastic resin, and a socket part 13 that is provided at one end of the pipe body 11 and into which the spigot part is inserted. The socket part 13 comprises a resin part 14 integral with the pipe body 11, and a reinforcing part 15 that reinforces the socket part 13 on the outer periphery of the resin part 14. A socket pipe thickness t4, which is the sum of the resin part 14 and the reinforcing part 15, is configured to be thinner than a pipe thickness t of the pipe body 11. The reinforcing part 15 is configured by winding a high-strength fiber sheet 15a around the resin part 14.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a liquid transport pipe that is to be inserted into an existing pipe for pipeline renewal, and a method for manufacturing the liquid transport pipe.

There is a pipeline renewal method for replacing an existing pipe for water flow laid on the ground with a new pipe (see Patent Document 1). In such a renewal method, a pipeline is renewed by inserting a liquid transport pipe as a new inner pipe into an existing pipe and connecting the water transport pipes to each other.

Japanese Patent No. 6644344

In the pipeline renewal method, the liquid transport pipe to be inserted into the existing pipe is to be inserted into the existing pipe. Therefore, the inner diameter of the pipeline becomes smaller after the renewal than before the renewal, and the flow rate also decreases. For this reason, in order to suppress the decrease in the flow rate due to the replacement of the pipe, it is required to use a pipe having an inner diameter as large as possible for the liquid transport pipe.

A liquid transport pipe for solving the above-mentioned problems is a liquid transport pipe to be inserted into an existing pipe, comprising a pipe body molded of a thermoplastic resin and a spigot portion at one end of the pipe body. is inserted, wherein the socket includes a resin portion integrated with the pipe main body, and a reinforcing portion that reinforces the resin portion on the outer circumference of the resin portion.

According to the above configuration, it is possible to reduce the thickness of the resin portion by providing the reinforcing portion in the receptacle portion. This makes it possible to insert a liquid transport pipe having a larger inner diameter into an existing pipe by reducing the outer diameter of the socket.

In the liquid transport pipe, the thickness of the resin portion may be thinner than the thickness of the pipe main body. According to the above configuration, by making the thickness of the resin portion thinner than the thickness of the pipe main body, it is possible to reduce the outer diameter of the socket of the socket.

In the liquid transport pipe, the reinforcing portion may have at least one of tensile strength and Young's modulus higher than that of the pipe main body. According to the above configuration, even if the thickness of the resin portion is reduced, the strength of the receptacle portion can be maintained high.

In the liquid transport pipe, the reinforcing portion may be configured by winding a high-strength fiber sheet around the resin portion. According to the above configuration, even if the thickness of the resin portion is reduced, at least the decrease in strength of the resin portion can be compensated for by the reinforcing portion formed by winding the high-strength fiber sheet.

In the liquid transport pipe, the high-strength fiber sheet may be impregnated with an impregnating agent for fixing to the resin portion. According to the above configuration, the reinforcing portion is firmly fixed to the resin portion with the adhesive.

In the liquid transport pipe, the resin portion may be polyethylene resin, and the impregnant may be epoxy resin. According to the above configuration, the reinforcing portion of the high-strength fiber sheet can be firmly fixed to the polyethylene pipe.

In the liquid transport pipe, the resin portion may include a heating element, and the socket portion may be electrically fused to the spigot portion. According to the above configuration, the connection of the liquid transport pipe can be an electrofusion joint.

A method for manufacturing a liquid transport pipe for solving the above problems is a method for manufacturing a liquid transport pipe to be an inner tube to be inserted into an existing pipe, the socket portion of the liquid transport pipe being molded from a thermoplastic resin. The thickness of the portion that becomes the thickness is reduced from the outer periphery, and a reinforcing portion is formed on the outer periphery of the thinned portion.

According to the present invention, a liquid transport pipe having a large inner diameter can be used as an internal intubation pipe for an existing pipe because the outer diameter of the socket portion is reduced.

The figure which shows the pipeline renewal work of the transportation pipe which supplies the water of the water source side laid on the slope land to the power generation equipment of a power plant. Process drawing of pipeline renewal work. Sectional drawing of a water transport pipe. FIG. 4 is an enlarged cross-sectional view of the socket; Sectional drawing which shows the state before processing of a socket part. Process drawing which shows the manufacturing method of a transport pipe. Process drawing of socket part outer surface processing. (a) is a front view of an adhesive application nozzle, and (b) is a side view. The perspective view which shows the state which fixes a reinforcement part to the resin part which comprises a receptacle part.

A water transport pipeline to which the present invention is applied and a method for manufacturing the same will be described below with reference to the drawings.
<Conduit renewal work>
The water transport pipe 4 to which the present invention is applied is an inner pipe for inserting an inner pipe into the pipe line of the existing pipe 3 to renew the pipe line. As shown in FIG. 1, one example of pipeline renewal work is pipeline renewal work for existing pipes 3 that have been used as water transport pipes in hydroelectric power plants. In hydroelectric power generation, water is supplied from a water source 1 such as a reservoir or regulating reservoir to a power plant where power generation equipment 2 is installed. Power is generated by rotating the water wheel. The existing pipe 3, which constitutes a pipeline connecting the water source 1 and the power generation facility 2, is an exposed pipe laid on a slope. A penstock or the like is used for the existing pipe 3 .

The existing pipe 3 is fixed to the slope by fixing bases 5 which are concrete structures provided at a plurality of locations. Pipeline renewal work is performed when the existing pipe 3 reaches the end of its service life, becomes aged, or is damaged. In pipeline renewal work, the existing pipe 3 is reused without being removed. In the pipeline renewal work, a new water transport pipe 4, which is an internal pipe, is inserted into the existing pipe 3.

FIG. 2 is a process chart of pipeline renewal work. In pipeline renewal work, an upper portion of the existing pipe 3 is removed to form an opening 6 in process P1. The opening 6 is for inserting the water transport pipe 4 as a liquid transport pipe and for connecting the water transport pipes 4 to each other. A cable crane 7 is installed on the pipeline of the existing pipe 3 . The inner peripheral surface of the existing pipe 3 is cleaned such as removing deposits adhering to the inner peripheral surface. Note that the opening 6 may be provided in a range extending to the lower portion of the existing pipe 3 .

In step P<b>2 , the water transport pipe 4 is transported to the opening 6 by the cable crane 7 and inserted into the existing pipe 3 through the opening 6 . The water transport pipe 4 is provided with a spacer, for example, on its outer periphery. The spacer is a member for forming a constant gap between the inner peripheral surface of the existing pipe 3 and the outer peripheral surface of the water transport pipe 4 .

In step P3, the water transport pipes 4 inserted into the existing pipe 3 are connected. Specifically, the water transport pipes 4 are connected by electrical fusion or the like by inserting the spigot portion 12 of the other water transport pipe 4 into the socket portion 13 of one of the water transport pipes 4 .

In step P4, when the operation of inserting the water transport pipe 4 into the existing pipe 3 is completed, the opening 6 provided in step P1 is closed. As an example, the removed part of the existing pipe 3 removed to form the opening 6 is used as the closing member 8 after being reinforced. A closing member 8 is attached to close the opening 6 . Also, the opening 6 is closed with a new closing member 8 .

In step P5, a solidifying material is injected into the gap formed between the inner peripheral surface of the existing pipe 3 and the outer peripheral surface of the water transport pipe 4 . The solidifying material is, for example, fluid non-shrink mortar, air mortar, or the like. For example, when the solidifying material is injected from the downstream portion, the solidifying material is filled so as to push up the air in the gap. Thereby, the gap is filled with the solidifying material.

<Water transport pipe>
FIG. 3 is a cross-sectional view of the water transport pipe 4. As shown in FIG. The water transport pipe 4 is a molded body using a high-density polyethylene material as a thermoplastic resin, and is a pipe excellent in chemical resistance, corrosion resistance, abrasion resistance, impact resistance, and light weight. The molding resin of the water transport pipe 4 may contain additives such as pigments, antioxidants and stabilizers. Also, the molding resin of the water transport pipe 4 may contain a coupling material. Furthermore, the molding resin of the water transport pipe 4 may contain glass fiber in order to increase the strength. The water transport pipe 4 is, for example, a pipe with a diameter of about 450 mm to about 2000 mm. In addition, the effective length L of one water transport pipe 4 in the pipe axis direction is approximately 1000 mm to 5000 mm.

The water transport pipe 4 includes a pipe main body 11, a spigot portion 12 provided at one end portion of the pipe main body 11 in the pipe axial direction, and a socket portion 13 provided at the other pipe end portion. The pipe main body 11 is a cylindrical portion forming a straight pipe and has a pipe thickness t. Further, the pipe body 11 has a pipe outer diameter D and a pipe inner diameter d.

The spigot portion 12 has a spigot inner diameter d1 which is the same as the pipe inner diameter d (pipe inner diameter d=spike inner diameter d1). As an example, the tube inner diameter d is 450 mm to 2000 mm. The spigot portion 12 has a spigot outer diameter D1 larger than the pipe outer diameter D (pipe outer diameter D<spike outer diameter D1). Furthermore, the spigot portion 12 has a spigot pipe thickness t1 that is thicker than the pipe thickness t (pipe thickness t<spigot pipe thickness t1). That is, the pipe main body 11 and the spigot portion 12 form the same inner peripheral surface, and the outer peripheral surface is swollen.

As shown in FIG. 4, the receptacle portion 13 has a receptacle outer diameter D2 that is larger than the pipe outer diameter D and the receptacle outer diameter D1 (pipe outer diameter D, receptacle outer diameter D1<receptacle outer diameter D2 ). The socket portion 13 has a socket inner diameter d2 larger than the pipe inner diameter d (pipe inner diameter d<receptacle inner diameter d2). That is, the socket portion 13 is the thickest portion among the pipe body 11, the socket portion 13, and the spigot portion 12 on the outer peripheral surface and the inner peripheral surface extending in the pipe axial direction.

As shown in FIG. 4 , the socket portion 13 includes a resin portion 14 and a reinforcing portion 15 . The socket portion 13 is a portion into which the spigot portion 12 is inserted. Therefore, the resin portion 14 of the socket portion 13 is a portion that is integral with the pipe body 11 and constitutes the inner peripheral surface of the socket portion 13 . The resin portion 14 has a resin portion thickness t2 that is thinner than the pipe thickness t of the pipe main body 11 (pipe thickness t>resin portion thickness t2). As shown in FIG. 5, the socket portion 13x before processing originally has a pipe thickness t3 before processing. Part thickness t2<pipe thickness before processing t3). As an example, the resin portion thickness t2 is a thickness having a minimum strength that allows at least the reinforcing portion 15 to be provided in the next step.

The socket portion 13x before processing has an outer peripheral surface shape including an outer peripheral straight portion 13a and an outer peripheral inclined portion 13b. It is connected. In addition, the shape of the inner peripheral surface includes an inner peripheral straight portion 13c and an inner peripheral inclined portion 13d. It is connected. Since the socket portion 13x is cut from the outer peripheral surface, its machined surface 13e approaches the inner peripheral surface, the outer peripheral straight portion 13a is slightly longer, and the outer peripheral inclined portion 13b is slightly shorter (see FIG. 5). reference).

As shown in FIG. 4 , the reinforcing portion 15 is provided on the outer periphery of the resin portion 14 to reinforce the thinned resin portion 14 and constitute the outer peripheral surface of the socket portion 13 . Specifically, the reinforcing portion 15 is a portion having higher tensile strength and Young's modulus than the resin portion 14 .

As an example, the tensile strength and Young's modulus of a glass fiber-filled polyethylene pipe used as the water transport pipe 4 are as follows.
Tensile strength: Circumferential direction: 40 MPa or more
Axial direction: 24 MPa or more Young's modulus: Circumferential direction: 2500 MPa or more
Axial direction: 1300 MPa or more The tensile strength and Young's modulus of the high-density polyethylene pipe used as the water transport pipe 4 are as follows.

Tensile strength: 27 MPa or more Young's modulus: 980 MPa or more On the other hand, as an example, the tensile strength and Young's modulus of the carbon fiber cloth sheet, which is the high-strength fiber sheet 15a constituting the reinforcing portion 15, are as follows.

Tensile strength (average value): 3400 MPa
Young's modulus (average value:) 245000 MPa
In this way, the reinforcing portion 15 has clearly higher tensile strength and Young's modulus than the resin portion 14 .

As an example, the reinforcing portion 15 is configured by winding a sheet material around the outer peripheral surface of the resin portion 14 . More specifically, the reinforcing portion 15 is configured by winding a high-strength fiber sheet 15 a around the outer peripheral surface of the resin portion 14 . The high-strength fiber sheet 15a as a reinforcing material is a carbon fiber cloth sheet, an aramid fiber sheet, or the like. The number of windings of the high-strength fiber sheet 15a around the resin portion 14 depends on the strength required for the socket portion 13 and the diameter of the water transport pipe 4, but is about 1 to 10 turns.

A carbon fiber cloth sheet is used here as the high-strength fiber sheet 15a. The reinforcing portion 15 is wound around the outer peripheral surface of the resin portion 14 to which the adhesive is applied while the high-strength fiber sheet 15a is impregnated with the impregnating agent. Here, the total thickness of the socket portion 13 including the resin portion 14 and the reinforcing portion 15 is the socket pipe thickness t4.

As an example, the reinforcing portion thickness t5, which is the thickness of the reinforcing portion 15, is made thinner than the cut portion of the socket portion 13x. In this case, the socket pipe thickness t4 is thinner than the unprocessed pipe thickness t3 (socket pipe thickness t4<pre-process pipe thickness t3), and the socket outer diameter D2 of the socket portion 13 is reduced. As an example, as shown in FIG. 4, the socket pipe thickness t4 can be made thinner than the pipe thickness t of the pipe main body 11 (socket pipe thickness t4<pipe thickness t). In this way, even if the thickness t4 of the socket portion 13 is thinner than the thickness t3 before processing, the strength of the socket portion 13 is equal to or higher than that of the socket portion 13x due to the existence of the reinforcing portion 15. can be high

Further, the step between the outer peripheral surface of the socket portion 13 and the outer peripheral surface of the pipe body 11 is small. As a result, when inserting into the existing pipe 3, the step is less likely to get caught on the existing pipe 3, and the insertion can be performed smoothly.

The reinforcing portion 15 is provided on at least a portion of the outer peripheral straight portion 13a. Preferably, the reinforcing portion 15 is provided in a range (processed surface 13e for thinning) from the tip S1 of the socket portion 13 to the boundary position S2 between the outer peripheral straight portion 13a and the outer peripheral inclined portion 13b. Since such a range is a range where the socket portion 13x is thinned and the strength is lowered, the reinforcing portion 15 is provided at least in this range. In the example of FIG. 4 , in order to further increase the reinforcing strength, it is provided from the tip S1 of the outer peripheral straight portion 13a to the boundary position S3 between the outer peripheral sloped portion 13b and the outer peripheral surface of the pipe main body 11 .

Here, when the resin portion 14 is made of polyethylene, it is difficult to bond the high-strength fiber sheet 15a with an adhesive. Therefore, the high-strength fiber sheet 15a is impregnated with an impregnating agent so that the high-strength fiber sheet 15a is firmly fixed to the resin portion 14 with an adhesive. The impregnating agent also faces the outer peripheral surface as the reinforcing portion 15 and is in contact with the solidifying material that fills the gap between the existing pipe 3 and the water transport pipe 4 . Therefore, an epoxy resin is used as the impregnating agent because it has excellent chemical resistance to calcium hydroxide, which is the main component of the solidifying material. More specifically, as the epoxy resin, a two-component epoxy resin, which is a thermosetting resin, is used. Since the reinforcing portion 15 is also a portion heated by the heating element 16, a thermosetting resin is used so that the heating of the heating element 16 does not cause deterioration.

As the adhesive, an adhesive capable of firmly bonding the resin portion 14 and the reinforcing portion 15 together is selected. As an example, a styrene-butadiene rubber-based solvent adhesive is used.
A heating element 16 is arranged in the resin portion 14 . The heating element 16 has a coil shape and is fixed to the inner peripheral surface of the resin portion 14 . A connection terminal of the heating element 16 is led out of the receptacle portion 13 . The heating element 16 is connected to the control device via a connection terminal, generates heat under set energization conditions, and melts the resin portion 14 . The inner diameter of the resin portion 14, that is, the socket inner diameter d2 of the socket portion 13, is the same as or substantially the same as the spigot outer diameter D1. In addition, the spigot length of the spigot portion 12 in the pipe axial direction is the same as or substantially the same as the spigot length of the socket portion 13 in the pipe axial direction.

<Method for manufacturing water transport pipe>
Next, a method for manufacturing the water transport pipe 4 configured as described above will be described. FIG. 6 is a process diagram of a method for manufacturing the water transport pipe 4. As shown in FIG. The water transport pipe 4 is manufactured, for example, by winding extrusion. That is, a belt-shaped planar resin obtained by extruding a thermoplastic resin material in a molten state from an extruder is spirally wound in one or more layers around a rotating cylindrical mold, and cooled and solidified. It is formed by letting

Then, in step P11, finishing treatment such as removal of burrs from the socket portion 13x of the water transport pipe 4 having the socket portion 13x before processing shown in FIG. 5 is performed. In step P12, finishing treatment such as removal of burrs from the spigot portion 12 on the opposite side of the socket portion 13x is performed.

In step P<b>13 , the heating element 16 is arranged on the inner peripheral surface of the socket portion 13 , that is, on the inner peripheral surface of the resin portion 14 . In step P<b>14 , a sheet is attached so as to cover the heating element 16 . This sheet constitutes the inner peripheral surface of the receptacle portion 13 facing the outer peripheral surface of the spigot portion 12 . The sheet covers the heating element 16 so that the irregularities on the surface of the heating element 16 do not appear on the inner peripheral surface of the receptacle part 13 . As a result, the spigot portion 12 can be smoothly inserted into the receptacle portion 13 by smoothing the inner peripheral surface thereof. Then, in step P<b>15 , the heating element 16 is heated to temporarily fuse the heating element 16 to the inner peripheral surface of the resin portion 14 . In step P16, the outer peripheral surface of the socket portion 13x is cut to reduce the thickness. Specifically, the socket portion 13x before processing is cut until the pipe thickness t3 before processing becomes the resin portion thickness t2. Here, it is inspected whether the outer diameter of the resin portion 14 before providing the reinforcing portion 15 is within the dimension standard value.

<How to fix the reinforcing part>
In step P<b>17 , the reinforcing portion 15 is provided on the outer peripheral surface of the resin portion 14 . Here, FIG. 7 is a process diagram showing a fixing method of the reinforcing portion 15 in the process P17.

In step P21, the periphery of the region where the reinforcing portion 15 is to be provided is cured. For example, the inner peripheral surface of the socket portion 13 is cured with a curing tape. This prevents the adhesive for applying the reinforcing portion 15 to the outer peripheral surface of the resin portion 14 from adhering to the inner peripheral surface of the receptacle portion 13 and the like.

In step P22, the high-strength fiber sheet 15a as a reinforcing material constituting the reinforcing portion 15 is cut into a predetermined length. The high-strength fiber sheet 15a is, for example, a carbon fiber cloth sheet. As an example, the carbon fiber cloth sheet has the following physical properties.

・Unidirectional high-strength cloth ・Fiber weight: 200 g/m ²
・Sheet thickness 0.111mm
・Density 1.80 g/cm ²
・Tensile strength (average value) 3400 MPa
・ Young's modulus (average value) 245000 MPa
Next, in step P23, the outer peripheral surface of the resin portion 14 is coated with an adhesive. 8A and 8B show a coating nozzle 21 for coating the outer peripheral surface of the resin portion 14 with an adhesive. The application nozzle 21 has a nozzle portion 21 a for ejecting the adhesive 22 . For example, the width of the nozzle portion 21a corresponds to the length of the outer peripheral surface of the resin portion 14 in the pipe axis direction. Alternatively, it is shorter than the length of the outer peripheral surface of the resin portion 14 in the pipe axis direction.

The water transport pipe 4 is set on a rotary shaft body whose rotation axis coincides with the pipe axis of the water transport pipe 4, and is rotated about the pipe axis (in the direction of the arrow in FIG. 8(b)). An adhesive is applied to the resin portion 14 of the rotating water transport pipe 4 by an application nozzle 21 . As a result, the adhesive 22 is applied to the outer peripheral surface of the resin portion 14 in the circumferential direction. The nozzle portion 21a includes a leveling portion 21b. When applying the adhesive 22 , the nozzle portion 21 a approaches the outer peripheral surface of the resin portion 14 and applies the adhesive 22 to the outer peripheral surface of the resin portion 14 . The leveling portion 21b is located downstream of the resin portion 14 in the rotational direction, close to the outer peripheral surface of the resin portion 14, and maintains a uniform coating thickness of the adhesive 22 to be applied. A guideline for the amount of adhesive to be applied is 70 to 100 g/m ² .

In step P24, the high-strength fiber sheet 15a is impregnated with an impregnating agent. An example of the impregnating agent is a two-liquid type epoxy resin. The impregnating device for impregnating the high-strength fiber sheet 15a with the impregnating agent controls the mixing ratio of the two liquids and impregnates the high-strength fiber sheet 15a with the mixed epoxy resin. As shown in FIG. 9, in step P25, the water transport pipe 4 having the adhesive 22 applied to the outer peripheral surface of the resin portion 14 is rotated about the pipe axis, and the outer peripheral surface of the rotating resin portion 14 is rotated. , the high-strength fiber sheet 15a impregnated with the impregnating agent 23 is wound. In step P26, the reinforcing portion 15 is dried.

Then, in step P18, the water transport pipe 4 is inspected. Specifically, dimensional inspection and quality inspection are performed. As an example, in the dimension inspection, it is inspected whether the inner diameter d2 of the socket is within the standard dimension value, and whether the outer diameter D2 of the socket portion 13 after providing the reinforcing portion 15 is within the standard dimension value. As a quality inspection, a radial load is applied to the socket portion 13 to inspect, for example, if the reinforcing portion 15 is peeled off due to a flatness of 5%.

<How to connect the water transport pipe>
The water transport pipe 4 manufactured as described above is inserted into the existing pipe 3 through the opening 6 provided in the existing pipe 3, as shown in FIGS. Since the water transport pipe 4 has a small step between the outer peripheral surface of the pipe main body 11 and the outer peripheral surface of the socket 13, it can be smoothly inserted into the existing pipe 3 from the opening 6, and smoothly moves through the existing pipe 3 to a predetermined position. can be moved to

In the existing pipe 3, the spigot portion 12 or socket portion 13 of the previously inserted water transport pipe 4 and the socket portion 13 or socket portion of the next inserted water transport pipe 4 which serves as a mating The mouth portion 12 is fitted. The spigot portion 12 and the receptacle portion 13 to be connected are centered, temporarily fixed, and further fixed with a fixture. Next, the control device is connected to the connecting terminals of the heating element 16 exposed to the outside. The control device causes the heating element 16 to generate heat for a predetermined period of time under the set energization conditions. As a result, the inner peripheral surface of the socket portion 13 and the outer peripheral surface of the spigot portion 12 are melted and then cooled for a predetermined period of time to be solidified and integrated. After that, by connecting other water transport pipes 4, a water transport pipe can be constructed.

<Effects of Embodiment>
The water transport pipe 4 as described above can obtain the following effects.
(1-1) In the receptacle portion 13, the reinforcing portion 15 is provided on the outer circumference of the resin portion 14, so that the thickness of the resin portion 14 can be reduced. As a result, the socket outer diameter D2 is reduced, so that the water transport pipe 4 having a larger pipe inner diameter d can be inserted into the existing pipe 3 .

(1-2) Since the water transport pipe 4 has a small step between the outer peripheral surface of the pipe main body 11 and the outer peripheral surface of the socket 13, it can be smoothly inserted into the existing pipe 3 from the opening 6, and can be smoothly moved to a predetermined position. Therefore, the pipeline renewal work on the slope is facilitated.

(1-3) Since the resin portion thickness t2 of the resin portion 14 is thinner than the pipe thickness t of the pipe main body 11 (pipe thickness t>resin portion thickness t2), the socket outer diameter D2 can be reduced accordingly. As an example, by making the socket pipe thickness t4 of the socket portion 13, which is a combination of the resin portion 14 and the reinforcing portion 15, thinner than the pipe thickness t of the pipe main body 11 (socket pipe thickness t4<pipe thickness t), The socket outer diameter D2 can be reduced.

(1-4) Since the reinforcing portion 15 has higher tensile strength and Young's modulus than the pipe body 11 and the resin portion 14, the socket portion 13 can be maintained at high strength even if the resin portion 14 is made thinner.
(1-5) The reinforcing portion 15 is constructed by winding a high-strength fiber sheet 15a around the resin portion 14. As shown in FIG. The high-strength fiber sheet 15 a has higher tensile strength and Young's modulus than the pipe body 11 and the resin portion 14 . Therefore, even if the thickness of the resin portion 14 is reduced, the reduction in strength of the resin portion 14 can be compensated for by the reinforcement portion 15 . For example, even if the socket pipe thickness t4 is thinner than the pipe thickness t of the pipe main body 11, its strength can be made equal to or higher than the strength of the socket portion 13x.

(1-6) The high-strength fiber sheet 15a is impregnated with an impregnating agent 23 for fixing to the resin portion . Therefore, the reinforcing portion 15 can be firmly fixed to the resin portion 14 by the adhesive 22 .

(1-7) The water transport pipe 4 is a polyethylene pipe, and the impregnating agent 23 is an epoxy resin. Therefore, the reinforcing portion 15 can be firmly fixed with an adhesive to the resin portion 14 made of polyethylene resin.

(1-8) The water transport pipe 4 has a heating element 16 in the resin portion 14 of the socket portion 13 . Therefore, the receptacle portion 13 can be electrically fused to the spigot portion 12 . As a result, the water transport pipes 4 can be connected to each other by an electric fusion joint.

It should be noted that the water transport pipe 4 as described above can also be implemented by appropriately changing it as follows.
- The manufacturing method of the water transport pipe 4 is not limited to the steps shown in Figs. As an example, in FIG. 7, the high-strength fiber sheet 15a as a reinforcing material is cut to a predetermined length (step P22), and the high-strength fiber sheet 15a is impregnated with the impregnating agent 23 (step P24). Then, the adhesive 22 is applied to the outer peripheral surface of the resin portion 14 (step P23), and the high-strength fiber sheet 15a impregnated with the impregnating agent 23 is wound around the outer peripheral surface of the resin portion 14 (step P25). good too.

- The heating element 16 may be arranged on the outer peripheral surface of the spigot portion 12 . In this case, the heating element 16 arranged on the outer peripheral surface of the spigot portion 12 may be covered with a sheet to make the surface smooth and temporarily fused (see steps P13 and P14). Thereby, the spigot portion 12 can be smoothly inserted into the receptacle portion 13 .

- The connection of the two water transport pipes 4 is not limited to the electric fusion joint. For example, the spigot portion 12 and the receptacle portion 13 may be fixed with an adhesive without providing the heating element 16, or a stopcock made of water-swellable rubber may be provided around the spigot portion 12. You may connect the spigot part 12 and the receptacle part 13 by using. Also, the stopcock may be made of styrene-butadiene rubber, ethylene-propylene-diene rubber, or the like, which does not have a water expansion function.

・Thermoplastic resin constituting the water transport pipe 4 is polypropylene (PP), polyvinyl chloride (PVC), ABS resin (acrylonitrile-butadiene-styrene resin), AS resin, acrylic resin (PMMA), etc., in addition to high-density polyethylene. There may be.

- The high-strength fiber sheet 15a may be other than the carbon fiber cloth sheet and the aramid fiber sheet. As an example, it may be a super high molecular weight polyethylene sheet or the like.
- The impregnating agent 23 with which the high-strength fiber sheet 15a is impregnated is not limited to epoxy resin, and may be other thermosetting resin (phenol resin, melamine resin, etc.).

The high-strength fiber sheet 15a is not wound around the resin part 14 while being impregnated with the impregnating agent 23, but the high-strength fiber sheet 15a pre-impregnated with a thermosetting resin is applied to the resin part coated with the adhesive 22. 14 may be wound.

- The reinforcing portion 15 may be configured by winding a normal sheet around the resin portion 14, the strength of which is lower than that of the high-strength fiber sheet 15a. Further, the reinforcing portion 15 may be made of a material other than the sheet material, for example, a resin different from the resin portion 14 .

As long as the strength required for the water transport pipe 4 is obtained, the reinforcing portion 15 should have either tensile strength or Young's modulus higher than that of the pipe main body 11 and the resin portion 14 . Further, if the strength required for the water transport pipe 4 can be obtained by increasing the number of turns, the reinforcing portion 15 may have lower tensile strength and Young's modulus than the pipe main body 11 and the resin portion 14 .

- The socket pipe thickness t4 should be thinner than the unprocessed pipe thickness t3 of the socket portion 13x before processing. Therefore, the socket pipe thickness t<b>4 may be thicker than the pipe thickness t of the pipe body 11 .
The reinforcing portion 15 may be provided from the tip S1 of the socket portion 13 to a position overlapping the outer peripheral surface of the pipe body 11 past the boundary position S3 to increase the strength of the socket portion 13 and the pipe body 11. .

- The spigot part 12 may add a waterproofing material to the outer peripheral surface. Water-swelling rubber, styrene-butadiene rubber having no water-swelling function, ethylene-propylene-diene rubber, or the like may be used as the waterproof material. Specifically, a groove may be provided in the circumferential direction on the outer peripheral surface of the spigot portion 12, and rubber may be arranged in the groove in the circumferential direction.

・As pipelines for pipeline renewal, it is also possible to apply to agricultural water pipelines, pipelines of water treatment facilities, pipelines of sewage facilities, pipelines of circulating water pipes in factories, pipelines of waterworks, etc. .
- The liquid to be transported may be water, seawater, sewage, or a chemical solution.

DESCRIPTION OF SYMBOLS 4... Water transport pipe 11... Pipe main body 12... Spigot part 13... Socket part 14... Resin part 15... Reinforcement part 15a... High-strength fiber sheet 16... Heating element 22... Adhesive 23... Impregnating agent

Claims (8)

A liquid transport pipe that serves as an internal tube to be inserted into an existing pipe,
a pipe body molded from a thermoplastic resin;
a receptacle into which a spigot is inserted at the end of the pipe body,
The socket portion includes a resin portion integrated with the pipe main body, and a reinforcing portion that reinforces the resin portion on the outer circumference of the resin portion. 2. The liquid transport pipe according to claim 1, wherein the thickness of the resin portion is thinner than the thickness of the pipe main body. 3. The liquid transport pipe according to claim 1, wherein at least one of tensile strength and Young's modulus of said reinforcing part is higher than said pipe main body. 4. The liquid transport pipe according to any one of claims 1 to 3, wherein the reinforcing portion is configured by winding a high-strength fiber sheet around the resin portion. 5. The liquid transport pipe according to claim 4, wherein the high-strength fiber sheet is impregnated with an impregnating agent for fixing to the resin portion. The resin portion is a polyethylene resin,
6. The liquid transport pipe according to claim 5, wherein the impregnating agent is an epoxy resin. The resin portion includes a heating element,
7. The liquid transport pipe according to any one of claims 1 to 6, wherein the receptacle is electrically fused to the spigot. A method for manufacturing a liquid transport pipe to be an internal tube to be inserted into an existing pipe, comprising:
thinning from the outer periphery of a portion to be a socket portion of the liquid transport pipe, which is molded from a thermoplastic resin;
A method for manufacturing a liquid transport pipe, wherein a reinforcing portion is formed on the outer periphery of the thinned portion.

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