Pipe joint and piping system

Abstract

To provide a pipe joint which prevents a user from forgetting to insert a movable part into a composite pipe when connecting the composite pipe.SOLUTION: A pipe joint 15 that is connected to composite pipes 10A and 10B having flexible pipes 11A and 11B and coatings 12A and 12B covering outer circumferential surfaces of the flexible pipes, includes: an inner cylindrical portion 106A disposed inside an end of the flexible pipe; a movable portion 105A having a flange portion 107A protruding radially outward from an end of the inner cylindrical portion and engaging with or facing an end surface of the compound pipe in a direction of a first axis O1; and a main body 110 configured separately from the movable part, a water blocking surface 103a1A of which contacts the inner or outer peripheral surface of the flexible pipe, thereby watertightly sealing a space between the main body and the flexible pipe; wherein a color difference between the colors of the flexible pipe and the flange is 1 or more in an L*a*b* display system specified in JIS Z 8781-4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to pipe fittings and piping systems. [Background technology]

[0002] One type of pipe joint known as a one-push joint is a conventional joint. To install a one-push joint, a movable part is inserted into the end of the pipe in advance. The movable part is a separate component from the pipe joint that protects the waterproof packing. Then, when the pipe and the movable part are inserted into the pipe joint by a certain length, the pipe and the movable part are connected to the pipe joint (see, for example, Patent Document 1).

[0003] In push-button fittings, for example, a waterproof gasket is placed on the outer surface of the pipe. For example, in metal pipe fittings, the waterproof surface, which is the part of the fitting that comes into watertight contact with the pipe, cannot be visually confirmed. For this reason, it is very important to follow the procedure up to the point just before inserting the pipe into the fitting. Specifically, it is important not to forget to insert the movable part into the pipe.

[0004] Even among external watertight fittings (external watertight fittings) where the fitting seals the water on the outer surface of the pipe, there are known metal fittings that allow the moving part to be visually inspected from the outside through an inspection window (see, for example, Patent Document 2). However, this pipe fitting achieves visual inspection by having a watertight packing on the inside of the pipe as well, so it is not a pure external watertight fitting. Note that there are also external watertight fittings in which the moving part is integrated with the pipe fitting rather than being a separate part. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-225857 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-198585 Summary of the Invention [Problem to be solved by the invention]

[0006] Furthermore, in the pipe fitting of Patent Document 2, the inner cylindrical portion, which is the guide portion for the movable portion, is made from metal casting or machined from a metal block in order to provide an inner peripheral O-ring groove, and therefore is inevitably thicker than a portion formed by press molding, etc., which poses the problem of increased pressure loss due to the pipe fitting. For this reason, from the perspective of reducing pressure loss, it is desirable to eliminate the inner cylindrical portion of the pipe fitting in the case of an external watertight fitting and use a movable portion with an inner cylindrical portion formed by press molding, etc. Furthermore, because the method of checking the moving parts is to look through a check window, the angle from which the moving parts can be seen is limited, and it is expected that it will be difficult to see the moving parts depending on the degree to which the pipe is tightened, etc. Because only such imperfect checking quality can be achieved, the method of Patent Document 2, which involves the increased cost of installing a waterproof packing on the inside, is not seen in the current domestic market.

[0007] The pipes connected to these pipe joints may be flexible pipes or composite pipes with a coating covering the outer surface of the flexible pipe. As mentioned above, it was stated that a movable part with an inner tube formed by press molding or the like is more desirable, but with regard to this movable part, it is important that the coating of the composite pipe does not come off even when the flexible pipe is swung in a direction that makes it easy to apply force when trying to peel it off, that it is easy to see that the coating has come off, and that it be combined with a composite pipe whose coating can be peeled off with light force.

[0008] The present invention has been made in consideration of such problems, and aims to provide a pipe fitting that prevents forgetting to insert a movable part into a composite pipe when connecting the composite pipe, and a piping system equipped with this pipe fitting. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention proposes the following means. (1) Aspect 1 of the present invention is a pipe fitting to be connected to a flexible tube and a compound pipe having a coating covering the outer surface of the flexible tube, the pipe fitting comprising: an inner tubular portion disposed inside the end of the flexible tube; a movable portion having a flange portion that protrudes radially outward from the end of the inner tubular portion and engages with or faces the end surface of the compound pipe in the first axial direction; and a main body that is configured separately from the movable portion and whose water-stopping surface contacts the inner or outer circumferential surface of the flexible tube, thereby providing a watertight seal between the flexible tube and the main body; and the pipe fitting is such that the color difference between the colors of the flexible tube and the flange portion is 1 or more in the L*a*b* display system defined in JIS Z 8781-4.

[0010] In this invention, for example, an operator exposes the flexible tube at the end of the compound pipe by, for example, stripping off the coating. The inner cylindrical portion of the movable part is inserted into the end of the flexible pipe, and the flange of the movable part is engaged with or opposed to the end face of the flexible pipe in the first axial direction. At this time, the color difference between the colors of the flexible pipe and the flange is 1 or more in the L*a*b display system defined in JIS Z 8781-4. This allows the operator to easily see the flange of the movable part from the flexible pipe of the compound pipe, preventing the operator from forgetting to insert the movable part into the compound pipe when connecting the compound pipe to a pipe joint. Then, by bringing the water blocking surface of the main body into contact with the inner or outer peripheral surface of the flexible tube, the space between the flexible tube and the main body can be sealed watertight.

[0011] (2) A second aspect of the present invention may be the pipe joint described in (1), in which the movable part is made of metal. In this invention, the thickness of the inner cylindrical portion of the movable portion, which is necessary to exhibit a predetermined rigidity, can be made thinner than when the movable portion is made of synthetic resin, for example.

[0012] (3) A third aspect of the present invention may be the pipe fitting according to (1) or (2), in which the collar portion is a warning color. In this invention, the color of the flange can draw the worker's attention to the flange.

[0013] (4) A fourth aspect of the present invention may be the pipe joint according to any one of (1) to (3), wherein the coating includes a foamed resin material. In this invention, the coating has heat insulating properties, so that the temperature of the water or the like flowing inside the flexible tube can be kept relatively constant.

[0014] (5) A fifth aspect of the present invention may be a pipe fitting according to any one of (1) to (4), wherein the coating comprises a single-layer corrugated pipe and support portions arranged on the corrugated pipe at intervals of 50 mm or more and 200 mm or less in the second axial direction of the corrugated pipe, the support portions having a plurality of support projections that protrude radially inward from the corrugated pipe and are arranged in a circumferential direction, the foaming ratio of the corrugated pipe is 1.05 times or more and 4 times or less, and the average wall thickness of the corrugated pipe is 0.4 mm or more.

[0015] In this invention, because the coating includes a single-layer corrugated pipe, the production costs of the composite pipe can be reduced compared to, for example, a case where the coating includes a multi-layer corrugated pipe. The corrugated pipe has an expansion ratio of 1.05 to 4 times, and an average wall thickness of 0.4 mm or more. This allows the corrugated pipe alone to ensure a certain level of thermal insulation performance. Furthermore, the corrugated pipe is provided with a support portion having a plurality of support protrusions, and the support portions are arranged on the corrugated pipe at intervals of 50 mm to 200 mm in the second axial direction. This reliably ensures an air layer between the corrugated pipe and the flexible pipe, further improving the thermal insulation performance of the composite pipe as a whole. Furthermore, the coating is crushed by an external force, which makes it easier to strip the coating from the flexible tube, while also preventing the coating from shifting in the second axial direction.

[0016] (6) A sixth aspect of the present invention is a piping system comprising the pipe joint according to any one of (1) to (5) and the composite pipe.

[0017] According to the present invention, a piping system can be constructed using a pipe joint that prevents forgetting to insert a movable part into a compound pipe when connecting compound pipes.

[0018] (7) A seventh aspect of the present invention may be a piping system according to (6), in which the flexible tube is primarily made of polyethylene resin, heat-resistant polyethylene resin, cross-linked polyethylene resin, polybutene resin, copper, aluminum, or magnesium.

[0019] (8) Aspect 8 of the present invention may be a piping system described in (6) or (7), in which the coating is primarily made of polyethylene resin, cross-linked polyethylene resin, polypropylene resin, olefin-based elastomer, or styrene-based elastomer. [Effects of the Invention]

[0020] The pipe joint and piping system of the present invention can prevent forgetting to insert the movable part into the compound pipe when connecting the compound pipe. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a partially cutaway perspective view of a piping system according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a partially exploded perspective view of a pipe joint of the piping system. [Figure 3] FIG. 3 is an enlarged cross-sectional view of a fixing portion of the pipe joint. [Figure 4] 5A to 5C are cross-sectional views illustrating a procedure for connecting a first compound pipe to the pipe joint. [Figure 5] FIG. 4 is a cross-sectional view of a main part of a piping system according to a second embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view taken along the line A1-A1 in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0022] (First embodiment) A first embodiment of a pipe joint and a piping system according to the present invention will be described below with reference to FIGS. As shown in FIG. 1, a piping system 1 of this embodiment includes a first compound pipe (composite pipe) 10A, a second compound pipe (composite pipe) 10B, and a pipe joint 15 of this embodiment. Here, the first compound pipe 10A and the second compound pipe 10B are each formed in a tubular shape, and the pipe joint 15 is formed in a cylindrical shape. The central axes (axial lines) of the first compound pipe 10A, the second compound pipe 10B, and the pipe joint 15 are arranged coaxially with a common axis. Hereinafter, the common axis will be referred to as the axis (first axis) O1, and the direction along the axis O1 will be referred to as the axis O1 direction. The direction perpendicular to the axis O1 will be referred to as the radial direction, and the direction going around the axis O1 will be referred to as the circumferential direction.

[0023] In this embodiment, the configuration of the first compound pipe 10A and the configuration of the second compound pipe 10B are identical to each other. Therefore, the configuration of the first compound pipe 10A is indicated by adding the capital letter "A" to the reference numeral. The configuration of the second compound pipe 10B corresponding to the first compound pipe 10A is indicated by adding the capital letter "B" to the reference numeral of the first compound pipe 10A. This avoids redundant explanation. For example, a flexible tube 11A (to be described later) of the first compound pipe 10A and a flexible tube 11B (to be described later) of the second compound pipe 10B have the same configuration.

[0024] The first compound pipe 10A has a flexible pipe 11A and a coating 12A. The flexible tube 11A and the covering 12A are each formed in a tubular shape. The flexible tube 11A is primarily made of cross-linked polyethylene resin. Here, "A is primarily made of B" means that A contains B at a mass ratio of 50% or more. The flexible tube 11A may contain a pigment component in addition to the cross-linked polyethylene resin. For example, the flexible tube 11A is white in color. The flexible tube 11A may be made primarily of polyethylene resin, heat-resistant polyethylene resin, polybutene resin, copper, aluminum, or magnesium.

[0025] The coating 12A covers the outer circumferential surface of the flexible tube 11A. The coating 12A includes a foamed resin material whose main component is an olefin-based elastomer. The coating 12A may include a pigment component in addition to the olefin-based elastomer. For example, the color of the coating 12A is blue or pink. The coating may be made primarily of polyethylene resin, cross-linked polyethylene resin, polypropylene resin, or styrene-based elastomer. The coating does not have to contain a foamed resin material.

[0026] The flexible tube 11A protrudes in the direction of the axis O1 beyond the coating 12A by turning back the end of the coating 12A. In other words, the end of the flexible tube 11A in the direction of the axis O1 is not hidden by the coating 12A. The second compound pipe 10B has a flexible tube 11B and a coating 12B that are configured similarly to the flexible tube 11A and the coating 12A of the first compound pipe 10A.

[0027] In this embodiment, the pipe joint 15 is an outer surface watertight joint that seals water on the outer peripheral surfaces of the composite pipes 10A, 10B. The pipe joint 15 is formed symmetrically with respect to a reference plane S1 that is perpendicular to the axis O1. The following description will focus on the configuration of the first side D1 of the pipe joint 15 in the direction of the axis O1 (hereinafter simply referred to as the first side D1; the outer side in the direction of the axis O1) relative to the reference plane S1. Here, the side opposite to the first side D1 in the direction of the axis O1 is defined as a second side D2 in the direction of the axis O1 (hereinafter simply referred to as the second side D2; the inner side in the direction of the axis O1). The pipe joint does not have to be formed symmetrically with respect to the reference plane S1.

[0028] Pipe joint 15 is connected to composite pipes 10A and 10B. As shown in Figures 1 and 2, pipe joint 15 includes a cylindrical joint body 101, caps 102A and 102B provided at the ends of joint body 101, and in-cores (movable parts) 105A and 105B (not shown). The main body 110 is made up of the components of the pipe joint 15 other than the in-cores (movable parts) 105A and 105B.

[0029] The joint body 101 is formed in a cylindrical shape. As shown in FIG. 1, a step 113 is formed on the inner circumferential surface of the joint body 101 on a reference plane S1. The step 113 protrudes radially inward from the inner circumferential surface of the joint body 101. The step 113 is provided around the entire circumferential direction. As shown in FIGS. 1 and 3, at the step 113, the inner diameter of the joint body 101 gradually (step-wise) decreases toward the second side D2. That is, a first step 101d and a second step 101e are formed on the inner circumferential surface of the joint body 101 toward the second side D2. As shown in FIG. 1, the step 113 is in contact with an in-core 105A that is formed separately from the joint body 101. In the following, the portion of the joint body 101 from the end face of the first side D1 of the joint body 101 to the step 113 will be referred to as the open end of the joint body 101.

[0030] As shown in FIG. 2, an outer flange portion 101b and a male thread portion 101c are formed on the outer peripheral surface of the end portion of the first side D1 of the joint body 101. The outer flange portion 101b projects radially outward from the joint body 101. The outer flange portion 101b extends around the entire outer circumferential surface of the joint body 101. The male thread portion 101c is formed on the outer peripheral surface of the joint body 101 at a portion located closer to the first side D1 than the outer flange portion 101b.

[0031] 1 and 3, the cap 102A is cylindrical in shape and has an outer diameter that gradually decreases toward the first side D1. The cap 102A includes a first tube 102aA having an internal thread formed on its inner circumferential surface, and a second tube 102bA that is located closer to the first side D1 than the first tube 102aA. The first tube 102aA is threadedly attached to the male thread portion 101c of the joint body 101. A step 102dA is provided on the inner circumference of the cap 102A at a portion corresponding to the boundary between the first tube 102aA and the second tube 102bA. The step 102dA extends over the entire circumferential direction. The step 102dA contacts or is close to the end face of the joint body 101 facing the first side D1.

[0032] The second tube 102bA has a smaller diameter than the first tube 102aA. The second tube 102bA extends from the first tube 102aA to the first side D1. In the pipe fitting 15, an accommodating recess 108A for accommodating a waterproofing portion 103A and a fixing portion 104A (described later) is formed between the fitting body 101 and the cap 102A. The accommodating recess 108A is formed between the step 102dA and the second step 101e of the fitting body 101. The accommodating recess 108A extends around the entire circumferential direction.

[0033] The joint body 101 and the cap 102A are formed by, for example, injection molding of a synthetic resin material, or cutting, casting, or forging of a metal material. The synthetic resin material can be selected arbitrarily based on quality design depending on the application, such as cross-linked polyethylene, polybutene, polyvinyl chloride (PVC), polysulfone resin (PSU), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyphenylsulfone resin (PPSU), polyphenylene sulfide resin (PPS), glass fiber reinforced PPS, polyvinylidene fluoride (PVDF), etc. Other processing methods such as cutting and fusion may also be used. The metal material can be arbitrarily selected from stainless steel, low alloy steel, carbon steel, low temperature carbon steel, low temperature alloy steel, brass, gunmetal, aluminum alloy, magnesium alloy, etc. based on quality design according to the intended use.

[0034] A gasket 103aA, a base 103bA, a retaining ring 104aA, a spacer 104cA, and a retaining ring 104bA are provided, in this order toward the first side D1, at the end of the first side D1 of the pipe fitting 15. The gasket 103aA and the base 103bA form the water-stopping part 103A, and the retaining ring 104aA, the spacer 104cA, and the retaining ring 104bA form the fixing part 104A. That is, the fixing portion 104A is located closer to the first side D1 than the waterproof portion 103A. The watertight portion 103A prevents the contents of the first compound pipe 10A from leaking out from the pipe joint 15. The first compound pipe 10A inserted into the pipe joint 15 is fixed to the pipe joint 15 by the fixing portion 104A.

[0035] The packing 103aA is disposed on the inner peripheral surface of the joint body 101. In the illustrated example, there is one packing 103aA, but multiple packings 103aA may be provided spaced apart in the direction of the axis O1. The packing 103aA is annular with a circular cross section. The packing 103aA extends over the entire circumference in the circumferential direction. In the illustrated example, an O-ring is used as the packing 103aA. The material of the gasket 103aA can be rubber material such as ethylene propylene diene rubber (EPDM), fluororubber (FKM), vinyl methyl silicone rubber (VMQ), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), chloroprene rubber (CR), etc. The surface of the packing 103aA facing inward in the radial direction forms a water stopping surface 103a1A.

[0036] The base 103bA is disposed between the packing 103aA and the retaining ring 104aA. The base 103bA prevents the packing 103aA and the retaining ring 104aA from coming into contact with each other. The base 103bA is formed in an annular shape. The base 103bA extends over the entire circumference. The base 103bA is fitted into the open end of the joint body 101. The base 103bA contacts the surface of the first step 101d of the joint body 101 that faces the first side D1. The base 103bA is hooked onto the first step 101d of the joint body 101 from the first side D1. The inner diameter of the base 103bA is larger than the inner diameter of the packing 103aA. The base 103bA is formed by, for example, injection molding of a synthetic resin material, or cutting, casting, or forging of a metal material.

[0037] The synthetic resin material can be selected arbitrarily based on quality design depending on the application, such as cross-linked polyethylene, polybutene, polyvinyl chloride (PVC), polysulfone resin (PSU), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyphenylsulfone resin (PPSU), polyphenylene sulfide resin (PPS), glass fiber reinforced PPS, polyvinylidene fluoride (PVDF), etc. Other processing methods such as cutting and fusion may also be used. The metal material can be arbitrarily selected from stainless steel, low alloy steel, carbon steel, low temperature carbon steel, low temperature alloy steel, brass, gunmetal, aluminum alloy, magnesium alloy, etc. based on quality design according to the intended use.

[0038] The retaining rings 104aA, 104bA, and spacer 104cA are disposed on the first side D1 with respect to the base 103bA. The retaining rings 104aA, 104bA, and spacer 104cA are disposed in the installation recess 108A of the joint body 101. The retaining rings 104aA, 104bA, and spacer 104cA are disposed so as to be movable with a slight amount of play in the direction of the axis O1 relative to the installation recess 108A. The retaining ring 104aA, spacer 104cA, and retaining ring 104bA are disposed in this order toward the second side D2. The spacer 104cA is disposed in the installation recess 108A, sandwiched between the retaining ring 104aA and the retaining ring 104bA in the direction of the axis O1.

[0039] 3, a step is formed on the second side D2 of the base 103bA. This step fixes the base 103bA to the joint body 101 so that it does not move to the second side D2. As a result, the packing 103aA is sandwiched between the base 103bA and the joint body 101, and is prevented from being crushed in the direction of the axis O1.

[0040] The first side D1 of the base 103bA faces the retaining ring 104aA, which is located between the base 103bA and the spacer 104cA. Although the retaining ring 104aA is in contact with the base 103bA in FIG. 3, the retaining ring 104aA can move in the direction of the axis O1.

[0041] The retaining rings 104aA and 104bA are formed by, for example, pressing a metal material. The metal material can be arbitrarily selected from stainless steel, low alloy steel, carbon steel, low temperature carbon steel, low temperature alloy steel, brass, gunmetal, aluminum alloy, magnesium alloy, etc. based on quality design according to the intended use.

[0042] The spacer 104cA is formed in an annular shape with a rectangular cross section that is longer in the direction of the axis O1 than its thickness. The spacer 104cA extends over the entire circumference. The inner diameter of the spacer 104cA is smaller than the inner diameter of the open end of the joint body 101. The inner diameter of the spacer 104cA is larger than the inner diameters of the retaining rings 104aA and 104bA. The retaining ring 104bA is sandwiched between the spacer 104cA and the cap 102A. The spacer 104cA is fixed to the installation recess 108A of the joint body 101. The retaining ring 104aA and the retaining ring 104bA are housed in the installation recess 108A of the joint body 101 so as to be movable in the direction of the axis O1 between the base 103bA and the spacer 104cA and between the spacer 104cA and the inside of the cap 102A, respectively.

[0043] The spacer 104cA is formed by, for example, injection molding of a synthetic resin material. The synthetic resin material can be selected arbitrarily based on the quality design appropriate for the application, such as cross-linked polyethylene, polybutene, polyvinyl chloride (PVC), polysulfone resin (PSU), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyphenylsulfone resin (PPSU), polyphenylene sulfide resin (PPS), glass fiber reinforced PPS, polyvinylidene fluoride (PVDF), etc.

[0044] The number of retaining rings that pipe fitting 15 has is not limited to two, and may be one, or three or more. Even when there are three or more retaining rings, a spacer is sandwiched between two adjacent retaining rings.

[0045] The base 103bA, retaining ring 104aA, spacer 104cA, and retaining ring 104bA are placed in this order in the accommodating recess 108A. The length of the accommodating recess 108A in the direction of the axis O1 is such that there is sufficient space between the retaining ring 104bA and the reduced diameter portion of the cap 102A.

[0046] As shown in FIGS. 1 and 2, the in-core 105A has an inner cylindrical portion 106A and a flange portion 107A. The inner cylindrical portion 106A is formed in a cylindrical shape and is disposed coaxially with the axis O1. The flange portion 107A protrudes radially outward from the end of the second side D2 of the inner cylindrical portion 106A. The flange portion 107A is formed around the entire circumference of the inner cylindrical portion 106A. The in-core 105A is made of a metal. The metal forming the in-core 105A can be arbitrarily selected from stainless steel, low-alloy steel, carbon steel, low-temperature carbon steel, low-temperature alloy steel, brass, gunmetal, aluminum alloy, magnesium alloy, etc., based on the quality design according to the intended use.

[0047] The in-core 105A may be formed from a resin material or the like. The resin forming the in-core 105A may be selected from a variety of materials, such as cross-linked polyethylene, polybutene, polyvinyl chloride (PVC), polysulfone resin (PSU), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyphenylsulfone resin (PPSU), polyphenylene sulfide resin (PPS), glass fiber reinforced PPS, polyvinylidene fluoride (PVDF), and the like, based on quality design appropriate for the intended use. The in-core may also be formed using other processing methods, such as cutting and fusion.

[0048] The color difference between the colors of the flexible tube 11A and the flange portion 107A of the incore 105A in the L*a*b* display system defined in JIS Z 8781-4:2013 is 1 or more. This color difference is preferably 10 or more, and more preferably 50 or more. The color of flange portion 107A may be the color of the outer peripheral surface of flange portion 107A, the color of entire flange portion 107A, or the color of entire in-core 105A. More specifically, the color of flange 107A is a warning color. For example, the warning color is yellow-green (yellow-green color), pink (pink color), etc. It is preferable that the color of flange 107A does not have a metallic luster. The coloring of the flange 107A can be carried out, for example, by painting and baking the metal surface forming the flange 107A, or by fitting a resin ring colored with a pigment.

[0049] The incore 105A is housed in a detachable state in the joint body 101. That is, the body 110 is configured as a separate body from the incores 105A and 105B.

[0050] As shown in FIG. 1 , the inner core 105A is housed in the joint body 101. The end of the first side D1 of the inner cylindrical portion 106A is located within the second cylinder 102bA of the cap 102A. The end of the first side D1 of the inner core 105A is located within the joint body 101, closer to the first side D1 than the packing 103aA. The inner cylindrical portion 106A of the inner core 105A is disposed radially inward of the packing 103aA, the base 103bA, the retaining ring 104aA, the spacer 104cA, and the retaining ring 104bA.

[0051] The first compound pipe 10A is connected to the pipe joint 15 configured as above. The inner cylindrical portion 106A of the in-core 105A is disposed inside the end of the flexible tube 11A of the first compound pipe 10A on the second side D2 in the axial direction O1. The flange portion 107A of the in-core 105A engages with or faces the end face of the flexible tube 11A of the first compound pipe 10A on the second side D2 in the axial direction O1. The flexible tube 11A of the first compound pipe 10A is disposed radially inward of the packing 103aA, the base 103bA, the retaining ring 104aA, the spacer 104cA, and the retaining ring 104bA. The flange 107A of the inner core 105A contacts the step 113 of the joint body 101 from the first side D1 of the step 113. At this time, the water blocking surface 103a1A of the packing 103aA of the main body 110 comes into contact with the outer circumferential surface of the flexible tube 11A, thereby sealing the flexible tube 11A watertightly.

[0052] Next, a procedure for connecting the first compound pipe 10A to the pipe joint 15 in the piping system 1 configured as above will be described. In the first compound pipe prepared in advance, the flexible pipe 11A is not exposed to the outside at the end in the direction of the axis O1. First, the worker exposes the flexible tube 11A by, for example, peeling off the coating 12A at the end of the first compound pipe 10A in the direction of the axis O1. In the pipe joint 15, the threaded engagement is released and the cap 102A is removed from the joint body 101. For example, the inner core 105A is removed from inside the joint body 101. The cap 102A is loosely threadedly engaged with the joint body 101.

[0053] As shown in FIG. 4 , the inner cylindrical portion 106A of the incore 105A is inserted into the end of the flexible tube 11A in the axial direction O1, and the flange portion 107A of the incore 105A is engaged with or opposed to the end face of the flexible tube 11A in the axial direction O1. At this time, the color difference between the colors of the flexible tube 11A and the flange portion 107A in the L*a*b display system defined in JIS Z 8781-4 is 1 or greater. Therefore, with the pipe fitting 15 of this embodiment, the operator can easily visually recognize the flange portion 107A of the incore 105A from the flexible tube 11A of the first compound pipe 10A, preventing the operator from forgetting to insert the incore 105A into the first compound pipe 10A when connecting the first compound pipe 10A to the pipe fitting 15. After this, the cap 102A is tightly screwed onto the fitting body 101. By bringing the water blocking surface 103a1A of the main body 110 into contact with the outer circumferential surface of the flexible tube 11A, the gap between the flexible tube 11A and the main body 110 can be sealed watertight.

[0054] In-core 105A is made of metal, and therefore, the wall thickness (thickness) of inner cylindrical portion 106A of in-core 105A required to exhibit a predetermined rigidity can be made thinner than when the in-core is made of synthetic resin, for example. The color of the flange 107A is a warning color. Therefore, the color of the flange 107A can call the worker's attention to the flange 107A. When working outside in the daytime, the metallic luster is dazzling and hurts the eyes, so the worker inserts the incore without looking at it just before insertion. However, with an incore that does not have a metallic luster, the worker can confirm the presence of the incore before inserting it, which allows for effective confirmation.

[0055] The coating 12A of the first compound pipe 10A includes a foamed resin material. This provides insulating properties to the coating 12A, which not only functions to keep the temperature of the water flowing inside the flexible pipe 11A relatively constant, but also reduces its relative rigidity. This reduces the need to use force to shake the coating when peeling it off, reducing the possibility of shaking off the in-core once it has been inserted. For this reason, in the piping system 1 of this embodiment, the piping system can be constructed using a pipe fitting 15 that prevents forgetting to insert the inner core 105A into the first compound pipe 10A when connecting the first compound pipe 10A.

[0056] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6. The same components as those in the above embodiment are designated by the same reference numerals, and a description thereof will be omitted. Only the differences will be described. As shown in FIGS. 5 and 6, a first compound pipe 20A provided in a piping system 2 of this embodiment has a coating 22A instead of the coating 12A in each configuration of the first compound pipe 10A.

[0057] The covering 22A has a single-layer corrugated tube 23A and a plurality of support portions 24A. Note that only one support portion 24A is shown in Figures 5 and 6. The corrugated pipe 23A is a pipe made of a corrugated thin plate. For example, the corrugated pipe 23A is formed from a low-density polyethylene resin. The average wall thickness of the corrugated pipe 23A is 0.4 mm or more. The foaming ratio of the corrugated pipe 23A is 1.05 times or more and 4 times or less. The support portion 24A has a plurality of (four in this embodiment) support protrusions 25A. The plurality of support projections 25A project radially inward from the corrugated tube 23A and are arranged side by side in the circumferential direction. The multiple support portions 24A are arranged on the corrugated pipe 23A at intervals of 50 mm to 200 mm in the direction of the second axis O2 of the corrugated pipe 23A. The intervals here refer to the distance between adjacent support portions 24A in the direction of the second axis O2.

[0058] The support portion 24A has a plurality of support protrusions 25A that contact the outer circumferential surface of the flexible tube 11A from the radially outer side of the flexible tube 11A. It is preferable that no lubricant such as silicone oil is applied between the flexible tube 11A and the coating 22A.

[0059] In the piping system 2 configured as described above, the sheath 22A includes the single-layer corrugated pipe 23A, which reduces the production cost of the composite pipe 20A compared to, for example, a case where the sheath includes multiple layers of corrugated pipe. The corrugated pipe 23A has an expansion ratio of 1.05 to 4 times, and an average wall thickness of 0.4 mm or more. This allows the corrugated pipe 23A to ensure a certain level of thermal insulation performance. Furthermore, the corrugated pipe 23A includes a plurality of support portions 24A, each having a plurality of support protrusions 25A. The support portions 24A are arranged on the corrugated pipe 23A at intervals of 50 mm to 200 mm in the direction of the second axis O2. This reliably ensures an air gap between the corrugated pipe 23A and the flexible pipe 11A, further improving the thermal insulation performance of the entire first composite pipe 20A. Furthermore, when the coating 22A is crushed by an external force, the coating 22A can be easily peeled off from the flexible tube 11A, and displacement of the coating 22A in the direction of the second axis O2 can be prevented.

[0060] 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 pipe joint may be an inner watertight joint having a main body whose watertight surface contacts the inner circumferential surface of the compound pipe and provides a watertight seal between the flexible pipes 11A and 11B. Also, the joint between the joint main body 101 and the cap 102 may be a fitted connection rather than by screwing in the male thread portion 101c or by locking with the outer flange portion 101b, and a lubricant such as silicone oil may be applied between the flexible pipe 11A and the coating 22A. [Explanation of symbols]

[0061] 1,2 Piping system 10A, 20A 1st composite pipe (composite pipe) 10B 2nd composite pipe (composite pipe) 11A,11B Flexible tube 12A, 12B, 22A coating 15 Pipe fittings 23A corrugated pipe 24A Support part 25A support protrusion 103a1A Water stop surface 105A In-core (moving part) 106A Inner cylinder part 107A Tsubabe 110 Main Unit O1 axis (1st axis) O2 2nd axis

Claims

1. A pipe joint to be connected to a flexible pipe and a composite pipe having a coating covering an outer circumferential surface of the flexible pipe, a movable part having an inner cylindrical part disposed inside an end part of the flexible tube, and a flange part protruding radially outward from the end part of the inner cylindrical part and engaging with or facing an end face of the compound pipe in a first axial direction; a main body that is configured separately from the movable portion, and whose water-stopping surface contacts an inner circumferential surface or an outer circumferential surface of the flexible tube, thereby watertightly sealing the space between the main body and the flexible tube; Equipped with A pipe joint, wherein the color difference between the colors of the flexible pipe and the flange is 1 or more in the L*a*b* display system defined in JIS Z 8781-4.

2. The pipe joint according to claim 1 , wherein the movable portion is made of metal.

3. 3. The pipe joint according to claim 1, wherein the flange is a warning color.

4. 3. The pipe joint according to claim 1, wherein the coating comprises a foamed resin material.

5. The coating is a single-layer corrugated pipe; support portions arranged on the corrugated pipe at intervals of 50 mm or more and 200 mm or less in a second axial direction of the corrugated pipe; and the support portion has a plurality of support protrusions that protrude radially inward from the corrugated pipe and are arranged side by side in the circumferential direction, The expansion ratio of the corrugated pipe is 1.05 times or more and 4 times or less, 3. The pipe joint according to claim 1, wherein the corrugated pipe has an average wall thickness of 0.4 mm or more.

6. The pipe joint according to claim 1 or 2; The composite pipe; A piping system comprising:

7. The piping system according to claim 6, wherein the flexible pipe is made primarily of polyethylene resin, heat-resistant polyethylene resin, cross-linked polyethylene resin, polybutene resin, copper, aluminum, or magnesium.

8. The piping system according to claim 6 , wherein the coating is made primarily of polyethylene resin, cross-linked polyethylene resin, polypropylene resin, olefin-based elastomer, or styrene-based elastomer.

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