Pipe conduit structure and connection method for pipe conduit structure

Abstract

To provide a resin pipe capable of visually recognizing that an outer peripheral surface of a pipe body has been scraped off in a state of being arranged in various directions.SOLUTION: A resin pipe 1 comprises a pipe body 11 made of an olefin-based resin, and a band-shaped part 13 formed on the outer peripheral surface of the pipe body so as to extend over the entire length of the pipe body 11, where a boundary line 13a between the pipe body 11 and the band-shaped part 13 is visible at any position in a circumferential direction of the pipe body 11, and the color difference in the L*a*b* color system defined in JIS Z8781-4:2013 is 1 or more between the colors of the pipe body 11 and the band-shaped part 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pipeline structure and a method for connecting the pipeline structure. [Background technology]

[0002] Conventionally, the use of resin pipes (pipe bodies) made of olefin-based resins such as polyethylene resins instead of metals to transport fluids such as water has been considered. By making the pipes out of olefin-based resins, corrosion of the pipes can be suppressed. Since adhesives do not easily adhere to resin pipes made of olefin-based resins, electric fusion methods are used to extend or branch resin pipes in the axial direction (see, for example, Patent Document 1). In the electric fusion method, the resin pipe and the electric fusion joint or the like are connected by heating and fusing them together while they are in contact with each other.

[0003] An oxide film or the like forms on the outer surface of the plastic pipe. When an oxide film or the like has formed, it is difficult to connect an electric fusion joint to the outer surface of the plastic pipe. For this reason, electric fusion joints or the like are electrically fused to the scraped off portion of the outer surface of the plastic pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-268628 A Summary of the Invention [Problem to be solved by the invention]

[0005] In order to easily determine whether the outer surface of a plastic pipe has been scraped off or not, a mark is written on the outer surface of the plastic pipe with an oil-based pen or the like, and part of the mark is then scraped off. If the remaining part of the mark remains on the plastic pipe, it can be visually confirmed that the outer surface of the plastic pipe has been scraped off. However, the task of marking the resin pipe is cumbersome, and it is also desirable for the mark to be visible even when the resin pipe is arranged in various orientations.

[0006] The present invention has been made in consideration of such problems, and aims to provide a pipeline structure using plastic pipes in which the removal of the outer peripheral surface of the pipe body can be visually confirmed when the pipe is arranged in various orientations, and a method for connecting this pipeline structure. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. The present invention provides a pipeline structure comprising a resin pipe and an electrically fused branch pipe, the resin pipe comprising a pipe main body made of an olefin-based resin and a band-shaped portion formed on an outer peripheral surface of the pipe main body so as to extend over the entire length of the pipe main body, the resin pipe having a central angle of 180° or less with respect to a portion of the outer peripheral surface of the resin pipe between a plurality of boundary lines between the pipe main body and the band-shaped portions that are adjacent in the circumferential direction when the resin pipe is viewed in the axial direction of the pipe main body, the color difference of the colors of the pipe main body and the band-shaped portions being 1 or more in the L*a*b* color system defined in JIS Z8781-4:2013, the electrically fused branch pipe being fixed to the outer peripheral surface of the pipe main body, the circumferential length of the portion of the electrically fused branch pipe in contact with the outer peripheral surface of the pipe main body being longer than the circumferential length between the band-shaped portions along the outer peripheral surface of the pipe main body.

[0008] According to this invention, the color difference between the colors of the pipe body and the band portion is 1 or more, and the boundary line between the pipe body and the band portion is visible at any position in the circumferential direction, so that the boundary line between the pipe body and the band portion can be easily seen when the plastic pipe is arranged in various orientations. Therefore, by visually checking that the band-shaped portion has been shaved off, it is possible to visually check that the outer peripheral surface of the pipe body has been shaved off when the plastic pipe is placed in various orientations. In addition, when connecting the resin pipe and the electrofusion branch pipe by electrofusion, the outer circumferential surface of the pipe body is scraped off in the circumferential direction by a length longer than the length of the electrofusion branch pipe in contact with the outer circumferential surface of the pipe body. Since the circumferential length of the portion of the electrofusion branch pipe in contact with the outer circumferential surface of the pipe body is longer than the circumferential length between the band-like portions along the outer circumferential surface of the pipe body, at least a portion of the band-like portion is scraped off. Therefore, it is possible to visually confirm that the outer circumferential surface of the pipe body to which the electrofusion branch pipe is electrically fused has been scraped off.

[0009] In the above-mentioned pipe structure, the thickness of the band-shaped portion may be 0.02 mm or more and 2.0 mm or less, and the thickness of the pipe body may be thicker than the thickness of the band-shaped portion.

[0010] In the above-described pipe structure, a lead angle that is an angle that the band-shaped portion makes with respect to a plane perpendicular to the axis of the pipe body may be 85° or more. According to this invention, it is possible to prevent the band-shaped portion from being inclined with respect to the axis of the pipe body, and to prevent deterioration in the appearance of the band-shaped portion extending over the entire length of the pipe body.

[0011] In addition, the method for connecting a pipeline structure of the present invention is a method for connecting a plastic pipe that connects any of the plastic pipes described above to a cylindrical electric fusion joint, and is characterized by carrying out a removal step in which the band-shaped portion of the plastic pipe is scraped off from an axial end of the pipe body along the axial direction to a length longer than a predetermined insertion length, and a fusion step in which, after the removal step, the plastic pipe is inserted into the electric fusion joint to the insertion length and the plastic pipe and the electric fusion joint are electrically fused together. According to this invention, the length of the strip portion that is scraped off is longer than the length of the plastic tube inserted into the electric fusion joint, so that even after the plastic tube and the electric fusion joint are connected, the boundary between the scraped off portion of the strip portion and the remaining portion that is not scraped off is exposed to the outside, making it possible to visually confirm that the outer surface of the plastic tube has been scraped off. Effect of the Invention

[0012] According to the conduit structure of the present invention, it is possible to visually confirm that the outer circumferential surface of the pipe body to which the electric fusion branch pipe is electrically fused has been scraped off. Also, according to the conduit structure connecting method of the present invention, it is possible to visually confirm that the outer surface of the plastic pipe has been scraped off even after connecting the plastic pipe and the electric fusion joint. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view of a resin pipe according to a first embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] 3 is a view taken in the direction of the arrow A1 in FIG. 2. [Figure 4] 3 is a view taken in the direction of the arrow A2 in FIG. 2. [Diagram 5] FIG. 2 is a diagram showing a schematic diagram of a manufacturing apparatus for the resin pipe. [Figure 6] 4 is a side view of a pipeline structure including the resin pipe and the electric fusion joint. FIG. [Figure 7] FIG. 4 is a perspective view illustrating a removing step in the resin pipe connecting method according to the first embodiment of the present invention. [Figure 8] FIG. 4 is a side view of a resin pipe in a modified example of the first embodiment of the present invention. [Figure 9] FIG. 4 is a perspective view of a pipeline structure according to a second embodiment of the present invention. [Figure 10] FIG. 2 is a plan view of a plastic pipe having the same pipeline structure. [Figure 11] 13 is a side view illustrating a method for measuring the width of the band-shaped portion of the resin pipe. FIG. [Figure 12] 1 is a photograph showing a resin pipe according to Example 1 of the present invention. [Figure 13] 1 is a photograph showing a resin pipe according to Example 2 of the present invention. [Figure 14] 1 is a photograph showing a resin pipe according to Example 3 of the present invention. [Figure 15] 1 is a photograph showing a resin pipe according to Example 4 of the present invention. [Figure 16] 13 is a photograph showing a resin pipe according to Example 5 of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (First embodiment) Hereinafter, a first embodiment of a resin pipe according to the present invention will be described with reference to FIGS. 1 to 8 and 11. FIG. 1 and 2, the resin pipe 1 of this embodiment includes a pipe body 11 and four band-like portions 13. In the following drawings, in order to distinguish the pipe body 11 from the band-like portions 13, the band-like portions 13 are shown hatched with dots. The pipe body 11 is formed into a tubular shape using polyethylene resin, which is an olefin resin. The polyethylene resin may be high-density polyethylene resin, medium-density polyethylene resin, etc. The olefin resin may be polypropylene resin, polybutene resin, etc., other than polyethylene resin. For example, the thickness of the pipe body 11 (the radial length of the pipe body 11) is 5 mm or more and 50 mm or less. The length of the pipe body 11 is 5 m. The olefin resin may contain inorganic fibers such as glass fiber, carbon fiber, and wollastonite. Furthermore, the pipe body 11 may be a multi-layer pipe in which an olefin resin layer is laminated with other layers, such as a layer containing inorganic fibers or a layer containing an oxygen barrier material. When the pipe body 11 is a multi-layer pipe, a band-shaped portion 13 is formed in the outermost layer for visibility. In order to connect with an electric fusion joint, it is preferable that the olefin resin layer is located outside the other layers, and in this case, the band-shaped portion 13 is formed in the olefin resin layer that is located outside the other layers. In the following description, the circumferential direction of the pipe body 11 will be simply referred to as the circumferential direction, and the radial direction of the pipe body 11 will be simply referred to as the radial direction.

[0015] The strip-shaped portion 13 is formed on the outer peripheral surface of the pipe body 11. The strip-shaped portion 13 extends over the entire length of the pipe body 11. In this example, each strip-shaped portion 13 is arranged along the axis C of the pipe body 11. The strip-shaped portions 13 are arranged at equal angles around the axis C with a space between them. The thickness of each strip-shaped portion 13 (the radial length of the pipe body 11) is appropriately determined according to the thickness of the pipe body 11, and is preferably 0.02 mm or more and 2.0 mm or less, more preferably 0.05 mm or more and 1.0 mm or less, and even more preferably 0.1 mm or more and 0.5 mm or less. By setting the thickness of each strip-shaped portion 13 within this range, the thickness is not too large, and it is easy to confirm that the strip-shaped portion 13 has been removed by the surface cutting work of the resin pipe 1 performed when connecting with the electric fusion joint. In addition, the thickness is not too small, and the color of the pipe body 11 cannot be seen through the strip-shaped portion 13 from the outside, so that the identification ability of the strip-shaped portion 13 can be exhibited. The thickness of each band-shaped portion 13 may be 0.3 mm or less. Furthermore, the thickness of the band-shaped portion 13 may be correlated with the thickness of the pipe body 11. For example, since the thickness T1 of the pipe body 11 varies depending on the nominal diameter, the preferred thickness T2 of the band-shaped portion 13 may vary depending on the corresponding nominal diameter. For example, the ratio T1 / T2 of the thickness T1 of the pipe body 11 to the thickness T2 of the band-shaped portion 13 may be 10 or more and 200 or less, preferably 20 or more and 150 or less. By setting the ratio to the lower limit of this range or more, the band-shaped portion 13 does not become too thick relative to the thickness of the pipe body 11, and it is easy to scrape off the band-shaped portion 13. Furthermore, by setting the ratio to the upper limit of this range or less, the band-shaped portion 13 has a sufficient thickness, and the identification ability of the band-shaped portion 13 can be fully exhibited. Furthermore, the band-shaped portion 13 may be formed by, for example, co-extrusion molding with the pipe body 11, or may be printed on the surface of the pipe body 11 after the pipe body 11 is extrusion molded. It is preferable that the circumferential length of the band-shaped portion 13 is constant regardless of the position in the axis C direction of the pipe main body 11.

[0016] The radial width of the band-shaped portion 13 is appropriately determined according to the outer diameter of the tube body 11, and is set to 4 mm or more and 50 mm or less, and preferably 8 mm or more and 40 mm or less. The ratio of the width of the band-shaped portion 13 to the outer diameter of the tube body 11 is set to 5% or more and 30% or less, and preferably 7% or more and 25% or less. The ratio of the width of the band-shaped portion 13 to the outer diameter of the tube body 11 referred to here means 100 times the value obtained by dividing the width of the band-shaped portion 13 by the outer diameter of the tube body 11. By setting the width of the band-shaped portion 13 within this range, the width is not too narrow, so that the band-shaped portion 13 can be distinguished from any direction. In addition, since the width is not too wide, an increase in manufacturing costs can be suppressed.

[0017] The radial width of the band-shaped portion 13 can be measured using a known vernier caliper 71, for example, as shown in Fig. 11. A slider 73 is moved along a body 72 of the caliper 71, and the outer measurement surfaces 75a, 76a of a pair of jaws 75, 76 are aligned with the first boundary lines 13a of the band-shaped portion 13, respectively, when the band-shaped portion 13 to be measured is in the state shown in Fig. 11 as viewed from the radial outside. At this time, it is preferable that the outer measurement surfaces 75a, 76a are arranged so as to be aligned along the axis C of the pipe main body 11. The value or scale displayed on the display 77 of the caliper 71 is read to measure the width of the band-like portion 13. The width of the band-like portion 13 is determined by this measurement method.

[0018] As shown in FIG. 1 and FIG. 2, the exposed surface 11a of the pipe body 11 where the band-shaped portion 13 is not formed and the outer surface of the band-shaped portion 13 are flush with each other. The radial step at the connection portion between the exposed surface 11a of the pipe body 11 and the outer surface of the band-shaped portion 13 is preferably 2.0 mm or less, and is preferably substantially stepless. In the circumferential direction, the length of the exposed surface 11a of the pipe body 11 and the length of the outer surface of the band-shaped portion 13 may be equal to each other or may be different from each other. It is preferable that the length of the exposed surface 11a of the pipe body 11 is longer than the length of the outer surface of the band-shaped portion 13. The four band-shaped portions 13 do not have to be arranged at equal angles around the axis C. The number of band-shaped portions 13 provided in the resin pipe 1 is not particularly limited, and may be one to three, or may be five or more.

[0019] The band-like portion 13 is preferably formed from the same material as the pipe body 11 . The color difference (ΔE) in the L*a*b* color system defined in JIS Z8781-4:2013 between the colors of the tube body 11 and the belt-like portion 13 is at least 1. This color difference is preferably at least 5, more preferably at least 10, and even more preferably at least 30. For example, the tube body 11 is blue and the belt-like portion 13 is red. The lightness (L*) of the color of the pipe body 11 or the color of the band portion 13 in the L*a*b* color system defined in JIS Z8781-4:2013 is preferably 20 or more, more preferably 30 or more. If the lightness of the color of the pipe body 11 or the color of the band portion 13 is 20 or more, the pipe body 11 or the band portion 13 can be seen even in a dark place such as a pipe space in which the plastic pipe 1 is installed. In the above color system, when L is 40 or more (preferably 50 or more) and the absolute values ​​of a and b are both 10 or less, the band portion 13 can be made gray. The gray plastic pipe 1 is used as a drainage pipe in a building structure in Japan. Therefore, for example, by making the band portion 13 gray, it is possible to suggest that the use of the plastic pipe 1 is a drainage pipe, even if the pipe body 11 itself is not made gray. As a result, for example, by adopting a pipe body 11 of the same color (e.g., blue) for both the water supply pipe and the drain pipe and adding the band-like portion 13 only to the pipe body 11 used as the drain pipe, it is possible to distinguish between the water supply pipe and the drain pipe. This makes it possible to reduce manufacturing costs, for example. In addition, in a drain pipe, the pressure of the fluid flowing inside is basically low, so the thickness of the pipe body 11 can be made thin.

[0020] The color difference can be measured using a spectrophotometer (handy spectrophotometer "NF333" manufactured by Nippon Denshoku Industries Co., Ltd.). It is preferable to measure the color difference in a darkened environment such as a darkroom. Here, the color difference (ΔE) is calculated by the following formula (1). ΔE=√((L1-L2) 2 +(a1-a2) 2 +(b1-b2) 2) (1) In formula (1), L1, a1, and b1 respectively represent the lightness L, chromaticity a in the red direction, and chromaticity b in the yellow direction of the belt-shaped portion 13, and L2, a2, and b2 respectively represent the lightness L, chromaticity a in the red direction, and chromaticity b in the yellow direction of the tube body 11.

[0021] Figures 3 and 4 show views taken along the arrows A1 and A2 in Figure 2. Figure 3 is a side view of the plastic pipe 1 as viewed from a position facing the band-shaped portion 13 in the circumferential direction of the pipe body 11. Figure 3 is a side view of the plastic pipe 1 as viewed from a position facing the exposed surface 11a of the pipe body 11 in the circumferential direction of the pipe body 11.

[0022] 3 and 4, in the plastic pipe 1, a first boundary line (boundary line) 13a is defined as a circumferential boundary line between the pipe body 11 and the band-shaped portion 13. Two first boundary lines 13a are formed corresponding to each band-shaped portion 13. The first boundary line 13a is visible from outside the plastic pipe 1 from any circumferential position viewed by a worker performing an installation operation on the plastic pipe 1. The fact that the first boundary line 13a is visible at any position in the circumferential direction means, for example, that the distance along the outer circumferential surface of the plastic pipe 1 between adjacent first boundary lines 13a in the circumferential direction is less than half the length of the outer circumferential surface over the entire circumference of the plastic pipe 1. In other words, as shown in FIG. 2, the central angle θ 1 is equal to or smaller than 180°. In this example, the four band-shaped portions 13 are arranged at 90° intervals around the axis C, so the first boundary line 13a is visible at any position in the circumferential direction.

[0023] It is sufficient that the first boundary line 13a is visible at any position in the circumferential direction at the end portion in the axial direction of the pipe body 11. It is more preferable that the first boundary line 13a is visible at any position in the circumferential direction, regardless of the position in the axial direction of the pipe body 11.

[0024] As shown in Fig. 1, a stencil (indicator portion) 15 is provided on the exposed surface 11a of the pipe body 11. The stencil 15 indicates, for example, the product name, model number, etc. of the resin pipe 1. The stencil 15 is formed by printing or the like using ink made of a material similar to that of the pipe body 11. The stencil 15 is arranged along the axis C.

[0025] Next, a manufacturing apparatus for manufacturing the resin pipe 1 configured as above will be described. As shown in Fig. 5, the manufacturing apparatus 51 includes a co-extrusion molding machine 52, a cooling section 53, a take-up machine 54, a printing machine 55, and a cutting machine 56. In Fig. 5, a portion of a molding die 52a described later that forms a second flow path 52c is indicated by a two-dot chain line so that the inside can be easily seen. The co-extrusion molding machine 52, the cooling section 53, the take-up machine 54, the printing machine 55, and the cutting machine 56 are arranged in this order from the upstream side toward the downstream side along which the resin pipe 1 (the continuous resin pipe 1A described later) is transported.

[0026] A first flow path 52b and a second flow path 52c are formed in a molding die 52a of the co-extrusion molding machine 52. In this embodiment, four second flow paths 52c are formed in the molding die 52a. The four second flow paths 52c merge with the first flow path 52b from the side of the first flow path 52b. A resin material for forming the pipe main body 11 is supplied in a molten state to the first flow path 52b. A resin material for forming the band-shaped portion 13 is supplied in a molten state to the second flow path 52c. The continuous resin pipe 1A is extruded downstream from the molding die 52a. The continuous resin pipe 1A is formed by continuously connecting the resin pipes 1 in the axial direction C.

[0027] The cooling section 53 is composed of a water tank, etc. The cooling section 53 cools the continuous resin pipe 1A molded by the co-extrusion molding machine 52 using water, etc. Although not shown, the take-up machine 54 has multiple endless tracks. The multiple endless tracks are arranged around the axis of the continuous resin pipe 1A at intervals. The multiple endless tracks are in contact with the outer circumferential surface of the continuous resin pipe 1A. When each endless track rotates in a predetermined direction, the continuous resin pipe 1A is taken up downstream.

[0028] The printer 55 prints a stencil 15 on the exposed surface 11a of the continuous resin pipe 1A, etc. The printer 55 may be disposed between the cooling unit 53 and the take-up machine 54. The cutter 56 cuts the continuous resin pipe 1A to a predetermined length to produce the resin pipe 1. The resin pipe 1 is manufactured by the manufacturing apparatus 51 described above.

[0029] Next, a method for connecting the resin pipe 1 configured as above to an electric fusion joint will be described. Here, the electric fusion joint will be described. As shown in Fig. 6, the electric fusion joint 21 is a known one formed in a cylindrical shape. The electric fusion joint 21 has a joint body 22, a pair of connector attachment parts 23, and a heating wire (not shown).

[0030] The joint body 22 is formed in a cylindrical shape from the same resin material as the resin pipe 1. The inner diameter of the joint body 22 and the outer diameter of the pipe body 11 are approximately the same. An end of the joint body 22 becomes a socket for the joint body 22. A stopper 25 is provided on the inner peripheral surface of the joint body 22 at the center in the axial direction of the joint body 22. For example, the stopper 25 is formed in an annular shape. For example, the insertion length L for inserting the plastic pipe 1 into the electric fusion joint 21 is calculated by subtracting the length of the stopper 25 from the length of the joint body 22 in the axial direction of the joint body 22 and dividing the result by 2. 1 Insertion length L 1 is determined in advance according to the specifications of the electric fusion joint 21 and the plastic pipe 1, etc.

[0031] The color of the outer surface of the joint body 22 is substantially the same as the color of either the pipe body 11 or the band-like portion 13 of the plastic pipe 1 to be inserted. This makes it easy to determine that the use of the electric fusion joint that connects the plastic pipes 1 is the same as that of the plastic pipe 1. Note that, "the color of the outer surface of the joint body 22 is substantially the same as the color of the pipe body 11 or the band-like portion 13 of the plastic pipe 1" means that the color difference between them is less than 10, preferably less than 8, and more preferably less than 5. The color of the inner surface of the joint body 22 may be either the color of the pipe body 11 or the color of the band-like portion 13, or may be a color different from these. Also, the color of the outer surface of the joint body 22 may be both the colors of the pipe body 11 and the band-like portion 13. Furthermore, an identification member provided separately from the joint body 22 may have the color of the pipe body 11 or the band-like portion 13, and the identification member may be a barcode indicating the electric fusion conditions, a barcode mount on which the barcode is written, or a tag for attaching these to the joint body 22.

[0032] The heating wire is embedded in the inner peripheral surface side of the joint body 22. The heating wire generates heat when a current flows through it. Each connector mounting portion 23 is attached to the outer circumferential surface at an axial end portion of the joint body 22. The connector mounting portions 23 are electrically connected to an end portion of the heating wire.

[0033] Next, a method for connecting the resin pipe 1 will be described. First, in the removing step (step S1), as shown in Fig. 7, an operator scrapes off the outer circumferential surface of the resin pipe 1. A known scraper is used for the scraping. The scraper is a machine that scrapes off the outer circumferential surface of the pipe body 11. The length to be scraped off in the direction of the axis C is the length L along the direction of the axis C from the end of the pipe body 11 in the direction of the axis C. 2 (Hereinafter, the cutting length L 2 When scraping off the outer circumferential surface of the pipe body 11, the scraping length L 2 In other words, for example, about 0.3 mm is removed from the outer peripheral surface of the pipe body 11. As shown in FIG. 2 is the insertion length L 1 Longer than. A typical scraper can scrape off about 0.15 mm of the thickness of the pipe body 11 per pass. When the scraper scrapes the outer circumferential surface of the pipe body 11 twice around the entire circumference, about 0.3 mm of the outer circumferential surface of the pipe body 11 is scraped off.

[0034] Next, in the fusion step (step S3), as shown in FIG. 6, the pipe body 11 of the resin pipe 1 is inserted into the joint body 22 of the electric fusion joint 21 by a length L 1 The resin pipe 1 and the electric fusion joint 21 are electrically fused. 2 is the insertion length L 1 Since the length of the strip 13 is longer than the width of the strip 13a, the second boundary line 13b, which is the boundary line in the direction of the axis C between the shaved-off portion and the portion that remains unshaved, is exposed to the outside and can be seen from the outside. When performing electric fusion, a connector of a joining controller (not shown) is connected to the connector attachment portion 23. The joining controller is operated to pass an electric current through the heating wire of the electric fusion joint 21 through the connector and the connector attachment portion 23. The heating wire generates heat, causing the joint body 22 of the electric fusion joint 21 and the pipe body 11 of the plastic pipe 1 to temporarily melt, and the pair of plastic pipes 1 are connected via the electric fusion joint 21. This fusion step S3 is performed after the above-mentioned removal step S1. With this, all steps of the method for connecting plastic pipes 1 are completed.

[0035] As described above, according to the plastic pipe 1 of this embodiment, the color difference between the colors of the pipe body 11 and the band portion 13 is 1 or more, and the first boundary line 13a between the pipe body 11 and the band portion 13 is visible at any position in the circumferential direction, so that the first boundary line 13a can be easily seen when the plastic pipe 1 is arranged in various orientations. Therefore, by visually checking that the band-shaped portion 13 has been removed, it is possible to visually check that the outer peripheral surface of the pipe body 11 has been removed with the plastic pipe 1 arranged in various directions. This makes it possible to prevent so-called cross-connection, in which the plastic pipe 1 is connected to another type of plastic pipe.

[0036] In addition, according to the method for connecting the resin pipe 1 of this embodiment, the insertion length L 1 The cutting length L 2 As a result, even after the plastic pipe 1 and the electric fusion joint 21 are connected, the second boundary line 13b of the belt-shaped portion 13 is exposed to the outside, and it can be visually confirmed that the outer surface of the plastic pipe 1 has been scraped away.

[0037] In the case of a resin pipe 1B shown in FIG. 8, the band-shaped portion 13 is formed in a spiral shape on the outer circumferential surface of the pipe body 11, and the lead angle θ, which is the angle that the band-shaped portion 13 makes with respect to a plane P perpendicular to the axis C of the pipe body 11, is 2 In addition, when the strip portion 13 is disposed along the axis C of the pipe main body 11, the lead angle θ 2 is 90°. With this configuration, it is possible to prevent the band-shaped portion 13 from being inclined with respect to the axis C of the pipe main body 11, and to prevent the appearance of the band-shaped portion 13 extending over the entire length of the pipe main body 11 from being deteriorated.

[0038] The thickness of the band-like portion 13 of the plastic pipe 1 may be 0.30 mm or less. In general, when using a scraper, the thickness of the plastic pipe that can be scraped off in one go is about 0.15 mm. When scraping a plastic pipe with a scraper, uneven scraping may occur, so the outer circumferential surface of the plastic pipe may be scraped off twice. During the process of scraping the plastic pipe 1 with the scraper, including measures to prevent uneven scraping, about 0.3 mm of the outer circumferential surface of the plastic pipe 1 is scraped off, so the band-like portion 13 can be scraped off from the end of the plastic pipe 1 within the range of normal work using a scraper. The thickness of the band-like portion 13 of the resin pipe 1 may be 0.15 mm or less. By configuring it in this manner, the band-like portion 13 can be scraped off from the pipe main body 11 by scraping off the outer circumferential surface of the pipe main body 11 with a scraper just once over the entire circumference.

[0039] Second embodiment Next, a second embodiment of the present invention will be described with reference to Figs. 9 and 10. The same components as those in the above embodiment are given the same reference numerals, and the description thereof will be omitted. Only the differences will be described. 9 and 10, the pipe structure 2 of this embodiment includes the above-mentioned resin pipe 1 and an electrofusion branch pipe 31. In addition, in Fig. 10, the area where the outer circumferential surface of the pipe body 11 is in contact with a support plate 32 (described later) of the electrofusion branch pipe 31 is indicated by a two-dot chain line. The electric fusion branch pipe 31 has a support plate 32, a branch pipe 33, a connector mounting portion 34, and an electric heating wire (not shown).

[0040] The support plate 32 is formed in a shape of a plate material curved into a semi-cylindrical shape. The inner diameter of the inner surface of the support plate 32 (the radius of curvature in the circumferential direction of the pipe body 11) and the outer diameter of the pipe body 11 are approximately the same. The branch pipes 33 protrude outward from the outer surface of the support plate 32. The branch pipes 33 penetrate the support plate 32. The outer diameter of the branch pipes 33 is smaller than the outer diameter of the pipe body 11 of the resin pipe 1. The heating wire is embedded on the inner surface side of the support plate 32. Each connector mounting portion 34 is attached to the outer surface of the support plate 32 so as to sandwich the branch pipes 33 in the direction of the axis C. The connector mounting portions 34 are electrically connected to the ends of the heating wires. The support plate 32 of the electric fusion branch pipe 31 is fixed to the outer circumferential surface of the pipe body 11 by electric fusion.

[0041] The outer circumferential surface of the resin pipe 1 is partially scraped off in the circumferential direction by a known hand scraper or the like. Here, the length in the circumferential direction of the inner surface of the support plate 32, which is the portion of the electric fusion branch pipe 31 that is in contact with the outer circumferential surface of the pipe body 11, is defined as the contact length L 4 The contact length L 4 is the removal length L, which is the circumferential length of the removal region R, which is the range in which the outer circumferential surface of the resin pipe 1 is removed. 5 In order to place the support plate 32 of the electric fusion branch pipe 31 in the removed region R of the resin pipe 1, the contact length L 4 is the removal length L 5 Similarly, the length of the inner surface of the support plate 32 in the axial direction C is shorter than the length of the removed region R in the axial direction C. In addition, the contact length L 4 is the length L between the band-shaped portions, which is the circumferential length between the band-shaped portions 13 along the outer circumferential surface of the pipe body 11. 63. Therefore, when forming the removed region R in the resin pipe 1, at least a part of the band-shaped portion 13 is cut off. Therefore, a third boundary line 13c is formed between the cut-off portion of the band-shaped portion 13 and the portion that remains uncut. This third boundary line 13c can be seen from the outside even after the resin pipe 1 and the electrofusion branch pipe 31 are connected by electrofusion. When the resin pipe 1 and the electrofusion branch pipe 31 are connected, the pipe line in the pipe body 11 of the resin pipe 1 and the pipe line in the branch pipe 33 of the electrofusion branch pipe 31 communicate with each other.

[0042] As described above, according to the conduit structure 2 of the present embodiment, when the resin pipe 1 and the electrofusion branch pipe 31 are connected by electrofusion, the contact length L of the electrofusion branch pipe 31 in contact with the outer circumferential surface of the pipe main body 11 along the circumferential direction of the outer circumferential surface of the pipe main body 11 is set to 0.05 mm. 4 The removal length L is longer than 5 The length between the strips L 6 Contact length L 4 Since the third boundary line 13c is longer, at least a part of the band-shaped portion 13 is scraped off. Therefore, it can be visually confirmed from the third boundary line 13c that the electrofusion branch tube 31 has scraped off the outer circumferential surface of the tube main body 11 to be electrofused.

[0043] Although the first and second embodiments of the present invention have been described above in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and the present invention also includes modifications, combinations, deletions, etc. of the configurations within the scope of the gist of the present invention. Furthermore, it goes without saying that the configurations shown in each embodiment can be used in appropriate combinations. For example, in the first and second embodiments, the stencil 15 does not have to be provided on the resin pipe. EXAMPLES

[0044] Next, examples 1 to 5 of the resin pipe 1 according to the first embodiment will be described. Note that examples 1 to 5 have different bore diameters (nominal diameters) as shown in Table 1 described later.

[0045] The measurement values ​​of the L*a*b* color system of the belt-shaped portion 13 of Examples 1 to 5 (each of the resin pipes 10A to 10E) are shown in Table 1. Note that in Table 1, the measurement values ​​of three types of L*a*b* color systems are shown for each Example. These respectively show the results of measurements taken at three different points on the belt-shaped portion 13.

[0046] [Table 1]

[0047] Table 2 shows the measurement values ​​of the L*a*b* color system for the tube body 11 of Examples 1 to 5.

[0048] [Table 2]

[0049] The color difference ΔE between the band-like portion 13 and the tube body 11 in Examples 1 to 5 is shown in Table 3. Note that in Table 3, three types of color difference ΔE are shown for each Example. These show the results of measurements taken at three different points on the band-like portion 13 and the tube body 11.

[0050] [Table 3]

[0051] The resin pipes 10A to 10E of Examples 1 to 5 are shown in Figures 12 to 16. When inspected with the naked eye, it was recognized that the pipe body 11 was blue and the band-like portion 13 was gray, and the boundary line 13a between them was also discernible.

[0052] For reference, Table 4 shows the L*a*b* color system values ​​for five test specimens of gray plastic pipes used in conventional drainage pipes.

[0053] [Table 4] [Explanation of symbols]

[0054] 1,1B resin pipe 2 Pipe structure 11 Tube body 13 Belt 13a First Boundary Line (Boundary Line) 21 Electric fusion joint 31 Electric fusion branch pipe L 1 Insertion Length L 4 Contact length (length) L 6 Length between strips (length) P plane θ 2 Lead angle

Claims

1. A resin pipe; An electric fusion branch tube; A pipeline structure comprising: The resin pipe is A pipe body formed of an olefin-based resin; a band-shaped portion formed on an outer peripheral surface of the pipe body so as to extend over the entire length of the pipe body; Equipped with When the resin pipe is viewed in the axial direction of the pipe body, the central angles of the outer peripheral surface of the resin pipe with respect to a plurality of boundary lines between the pipe body and the band-shaped portion adjacent in the circumferential direction are all 180° or less, The color difference in the L*a*b* color system defined in JIS Z8781-4:2013 for each of the colors of the tube body and the belt-shaped portion is 1 or more; The electric fusion branch pipe is fixed to the outer circumferential surface of the pipe body, A pipe structure in which the circumferential length of the portion of the electrically fused branch pipe that is in contact with the outer peripheral surface of the pipe body is longer than the circumferential length between the band-shaped portions along the outer peripheral surface of the pipe body.

2. The thickness of the strip portion is 0.02 mm or more and 2.0 mm or less, The pipe structure according to claim 1 , wherein the thickness of the pipe body is greater than the thickness of the band-shaped portion.

3. 3. The pipe structure according to claim 1, wherein a lead angle, which is an angle that the band-shaped portion makes with respect to a plane perpendicular to an axis of the pipe body, is 85 degrees or more.

4. A method for connecting a conduit structure according to any one of claims 1 to 3 to a cylindrical electric fusion joint, comprising: a removing step of removing the band-shaped portion of the resin pipe from an axial end of the pipe body along the axial direction by a length longer than a predetermined insertion length; a fusion step of inserting the plastic tube into the electric fusion joint by the insertion length after the removing step, and electrically fusion-bonding the plastic tube and the electric fusion joint; A method for connecting a duct structure.

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