Connection structure for piping

Abstract

To provide a connection structure for piping which can improve workability.SOLUTION: A connection structure for piping includes an electric fusion joint 30, and a piping 6 having a piping body 6a, and an insertion port 6b extending from an end part of the piping body 6a in a pipe axial direction and inserted into the electric fusion joint 30. The end part of the piping body 6a in the pipe axial direction is provided with a stopper part 6a1 which can come into contact with an end part of the electric fusion joint 30 in the pipe axial direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pipe connection structure. [Background technology]

[0002] When connecting polyethylene pipes, a connection structure using an electrofusion joint is known. The following Patent Document 1 describes that the pipe end of the coated polyethylene pipe 100 can be connected by inserting the pipe end into the socket 16 of the fitting body 12 until it abuts against the stopper 20, and then passing electricity through the heating wire 18 from the controller via the terminal part 22 to fuse it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-167768 Summary of the Invention [Problem to be solved by the invention]

[0004] When inserting a pipe into an electric fusion joint, if the pipe is not inserted all the way to the stopper and is inserted partway through, even if the heating wire is energized, the pipe may not fuse, resulting in poor installation. Therefore, in the above-mentioned configuration, to confirm after insertion that the pipe has been inserted all the way to the joint's stopper, a mark is drawn on the pipe to indicate when it is inserted to the joint's stopper, and after insertion, a visual check is made to ensure that the position of the mark matches the position of the joint end face, thereby confirming that the connection is secure. However, if the installer forgets to draw the mark, it becomes unclear whether the joint was installed properly, which can require the installer to start over, making the installation more complicated.

[0005] In view of the above-mentioned circumstances, an object of the present invention is to provide a pipe connection structure that can improve workability. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following aspects. <1> A piping connection structure according to one aspect of the present invention includes: an electric fusion joint; a pipe having a pipe body and a spigot extending from an end of the pipe body in the pipe axis direction and inserted into the electric fusion joint; Equipped with A stopper portion that can come into contact with the end portion of the electric fusion joint in the pipe axis direction is provided at the end portion of the pipe body in the pipe axis direction.

[0007] <1> According to this pipe connection structure, the spigot extending from the end of the pipe body in the pipe axis direction is inserted into the electrofusion joint, the stopper portion at the end of the pipe body in the pipe axis direction is abutted against the end of the electrofusion joint in the pipe axis direction, and electricity is passed through the electrofusion joint to connect the pipe and the electrofusion joint. If the spigot is inserted into the electrofusion joint by the appropriate length, the stopper portion of the pipe body and the end of the electrofusion joint will be in abutting state after connection, and this can be visually confirmed to confirm that the connection is correct. This eliminates the need for tedious tasks such as marking lines for confirmation, thereby improving workability. Furthermore, since marking lines is no longer necessary, there is no need for tedious tasks such as redoing the installation due to forgetting to mark lines, which also improves workability. Furthermore, since the structure is such that the insertion port extending from the pipe body of the pipe is inserted into the electric fusion joint and the stopper portion at the end of the pipe body in the pipe axis direction is abutted against the end of the electric fusion joint, the amount of radial outward protrusion of the electric fusion joint from the pipe body can be reduced, thereby preventing the electric fusion joint from hindering installation, which also makes it possible to improve installation ease. In addition, since the stopper portion at the end of the piping body in the axial direction of the piping is abutted against the end of the electric fusion joint, the gap opening to the outer periphery between the end of the piping body in the axial direction of the piping and the end of the electric fusion joint in the axial direction of the piping can be reduced, making it possible to prevent dirt and the like from adhering to this gap.

[0008] <2> The aforementioned <1> In the piping connection structure related to It is preferable that the outer diameter of the electrofusion joint is equal to the outer diameter of the piping body. In this way, by making the outer diameter of the electric fusion joint equal to the outer diameter of the piping body, the amount of radial outward protrusion of the electric fusion joint from the piping body can be eliminated, which further prevents the electric fusion joint from hindering installation and further improves ease of installation.

[0009] <3> The aforementioned <1> or <2> In the piping connection structure related to The electric fusion joint and the pipe preferably constitute a rehabilitation pipe that is housed inside an existing pipe. In this way, by constructing a rehabilitation pipe that is housed inside the existing pipe, the amount of radial outward protrusion of the electric fusion joint from the pipe body is reduced, which prevents the electric fusion joint from getting caught on other parts when moving within the existing pipe, thereby preventing construction from being hindered, and further improving construction ease. [Effects of the Invention]

[0010] As described above, the present invention has the effect of making it possible to improve workability. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view showing a resin pipe and an electric fusion joint to which a piping connection structure according to an embodiment of the present invention is applied. [Figure 2] 1 is a side view showing a state in which a resin pipe to be joined is attached to an electric fusion joint in a piping connection structure according to an embodiment. FIG. [Figure 3] 10 is a side view showing a state in which electricity is being applied from a controller to an electrofusion joint in the piping connection structure of the embodiment. FIG. [Figure 4] 1 is a side view showing a state in which resin pipes are fused together using an electric fusion joint in a piping connection structure according to an embodiment. FIG. [Figure 5]1 is a partial cross-sectional view showing an example of a piping structure including a piping connection structure according to an embodiment; [Figure 6] FIG. 6 is a partial cross-sectional view showing a state in which an inlet-side vertical hole and an outlet-side vertical hole have been formed to create the piping structure shown in FIG. 5. [Figure 7] FIG. 6 is a partial cross-sectional view showing a state in which multiple resin pipes are inserted into an existing piping from an inlet-side vertical hole to create the piping structure shown in FIG. 5. [Figure 8] A cross-sectional view showing the state in which a resin pipe that has been extended inside an existing pipe is moved to the outlet-side vertical hole side in order to realize the piping structure shown in Figure 5. [Figure 9] 6 is a cross-sectional view showing the operation of moving the resin pipe that has been added inside the existing piping to realize the piping structure shown in FIG. 5. [Figure 10] FIG. 6 is a partial cross-sectional view showing the state before the resin pipe extended inside the existing piping to realize the piping structure shown in FIG. 5 is fused to the resin pipe located below the outlet-side vertical hole. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a pipe connection structure according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, the pipe connection structure according to this embodiment is a structure in which a plurality of straight resin pipes 6 (pipes) are spliced ​​together via electrofusion joints 30. Each of the resin pipes 6, 6 to be spliced ​​together in this embodiment has a pipe body 6a and an insertion port 6b at an end in the pipe axis direction, which is the direction in which the central axis of the resin pipe 6 extends, and the insertion ports 6b are joined together via electrofusion joints 30 as shown in Fig. 1. The fusion portion between the electrofusion joint 30 and the resin pipe 6 will be described in detail later, but first the resin pipe 6 will be described.

[0013] The resin pipe 6 is preferably made of a thermoplastic resin such as a polyolefin-based resin. Resin pipe 6 made of a polyolefin-based resin has a higher tensile breaking elongation measured in accordance with JIS K 6815-1 and JIS K 6815-3 than rigid polyvinyl chloride pipe. While the tensile breaking elongation of rigid polyvinyl chloride pipe is 50 to 150%, the tensile breaking elongation of polyolefin-based resin pipe is 350% or more. In particular, by the extrapolation method specified in ISO / TR9080, a PE100 high-density polyethylene pipe has a tensile breaking elongation of 500% or more, which can better prevent damage caused by earthquakes.

[0014] The polyolefin resin is not particularly limited, but suitable examples include polyethylene, polypropylene, polybutene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, poly-α-olefin, etc. Among these, it is desirable to use polyethylene from the viewpoint of strength, etc. When selecting polyethylene, it is desirable to appropriately select any of low-density polyethylene, medium-density polyethylene, high-density polyethylene, etc. depending on the durability desired for the resin pipe 6. A resin pipe 6 made of polyethylene resin can be used from the viewpoint of not affecting earthquake resistance, durability, water quality, etc. In particular, when the resin pipe 6 is used as a drinking water pipe, a resin pipe made of high-density polyethylene is preferable.

[0015] The melt mass flow rate (MFR) of the thermoplastic resin is, for example, preferably 0.1 to 25 g / 10 min, more preferably 0.1 to 10 g / 10 min, and even more preferably 0.29 to 0.45 g / 10 min. When the MFR is equal to or greater than the lower limit, molding becomes easy. When the MFR is equal to or less than the upper limit, thermal stability can be further improved. MFR can be measured in accordance with JIS K 7210:1999 at a test temperature of 220°C and a test load of 10 kg. The melting point of the thermoplastic resin (ie, the melting temperature of the resin pipe 6) is preferably 150°C to 260°C, and more preferably 180°C to 240°C. The resin material may contain, in addition to the thermoplastic resin, known additives such as pigments, ultraviolet absorbers, antioxidants, and lubricants, as well as fillers. The resin pipe 6 may be a multi-layer pipe having three or more layers including a metal layer as an intermediate layer. Suitable metal materials for the metal layer include, for example, iron, brass, copper, stainless steel, aluminum, titanium, and silver alloy.

[0016] The resin pipe 6 may have a multi-layer structure having a surface layer on at least one of the outer peripheral surface and the inner peripheral surface. For example, by having a surface layer containing ethylene-vinyl alcohol copolymer resin, the resin pipe 6 may be a pipe for any purpose, such as a drinking water pipe, a gas pipe, or a sewer pipe. This is because the surface layer containing ethylene-vinyl alcohol copolymer resin makes it difficult for gases such as hydrogen, oxygen, propane, and butane, and hydrocarbons such as gasoline and benzene to permeate.

[0017] The surface layer may contain, for example, at least one of inorganic fibers and organic fibers. Examples of inorganic fibers include glass fibers, carbon fibers, silicon-titanium-carbon composite fibers, boron fibers, and metal fibers. Examples of organic fibers include aramid fibers, vinylon fibers, polyester fibers, and polyamide fibers. When the surface layer contains these fibers, the tensile strength of the resin pipe 6 can be increased and thermal expansion can be further suppressed. The surface layer may also contain a fluororesin. When the surface layer contains fluorine, resistance (chemical resistance) to acids, alkalis, and the like can be improved. Furthermore, a layer similar to the above surface layer may be provided inside the wall of the resin pipe 6.

[0018] The SDR value, which is the ratio of the outer diameter D to the wall thickness T of the resin pipe 6, is preferably 13.5 or less. If the SDR value exceeds 13.5, the pipe wall becomes too thin and may not be able to withstand the internal pressure of the fluid when it flows inside. If the SDR value is too low, the pipe wall becomes too thick and may not be able to ensure a sufficient flow rate. For this reason, the lower limit of the SDR value is preferably 6 or more, and more preferably 7.4 or more. This configuration is preferable for the resin pipe 6 when used for drinking water, but if the pipe is used for purposes other than sewage where internal pressure is not applied, the SDR value may be greater than 13.5, and is not particularly limited. From here on, up to paragraph "0029," the content is limited to drinking water applications, but the invention can also be used for other applications.

[0019] Generally, in pipe thickness design, for pipes with water flowing inside, the relationship that follows the Naday equation shown in equation (1) below is known to represent the tensile circumferential stress (tensile stress generated in the circumferential direction in the cross section of the pipe) generated in the pipe due to the internal water pressure. σ=P(Dt) / 2t …(1) formula In equation (1), σ is the tensile circumferential stress generated in the pipe (MPa), P is the internal water pressure (MPa), D is the outer diameter of the pipe (mm), and t is the thickness of the pipe (mm).

[0020] Based on the Naday formula mentioned above, it is preferable to design the pipe thickness so that the stress generated at the design internal pressure (maximum allowable stress) has a safety factor of 2 for the 50-year creep strength of polyethylene water distribution pipe. For example, this relationship can be expressed by the following formula (2). σ 50 / S1=P d (Dt) / 2t …(2) formula However, in equation (2), σ 50 : 50-year creep strength of polyethylene water distribution pipe (10 MPa), S1: σ 50 Safety factor for (here assumed to be 2), P d : Maximum allowable pressure (hydrostatic pressure 0.75 x water hammer pressure 0.25 = 1.0 PMa) By modifying the above equation (2), the value of SDR (Standard Dimension Ratio) can be calculated using the following equation (3). SDR=D / t=1+(2σ 50 ) / P d ·S1=1+(2×10) / (1×2)=11…(3) formula

[0021] According to the pipe thickness design for water pipes, which was calculated with the aforementioned safety factor of 2, it is clear that an SDR value of 11 is preferable, but if the purpose is to rehabilitate pipes such as polyethylene sewer pipes, where the internal pressure of the pipe can be estimated to be low, an SDR value of 13.5 or less is desirable. Furthermore, if the standard SDR value for polyethylene water pipes is 11, the SDR value will be less than SDR6 when the flow rate drops by 40% (calculated based on a flow velocity coefficient of 140 and a hydraulic gradient of 3%), so an SDR value of 6 or more is preferable.

[0022] As will be described later, when the resin pipe 6 is a pipe to be housed inside the existing pipe 1 shown in Fig. 5, it is a self-supporting pipe, not a pipe with a thin inner lining used in the prior art that cannot stand on its own. Moreover, it is preferable that the resin pipe 6 be a resin pipe with little deformation and an ovality of 4.5 mm or less. The measurement method for the ovality of the resin pipe 6 should preferably comply with the Japan Water Works Association standard: JWWA K 144 (Polyethylene pipe for water distribution). Measure each dimension of the resin pipe with a measuring device such as a vernier caliper at 23±2°C 24 hours or more after manufacture, and allow the pipe to condition for at least four hours before measurement. Furthermore, if the temperature measurement is outside of 23±2°C, such as when measuring dimensions outdoors, convert the measured values ​​to dimensions at 23°C using the following formula (4).

[0023] L 23 ={1+α×(23-t)}×L t …(4) formula In equation (4), L 23 : Dimensions at 23°C (converted value), α: Linear expansion coefficient (1 / °C) (polyethylene pipe for water distribution: 12.0 x 10 -5 ), t: Temperature at time of measurement (℃), L t : Dimensions (measured) at t℃ For example, in equation (4), if the outer diameter of a straight pipe with a nominal diameter of 100 is measured at an air temperature of 35°C (the temperature of the resin pipe is also 35°C) and the measured value is 125.9 mm, the converted value at 23°C will be 125.7 mm as calculated by the following formula. D 23 ={1+12.0×10 -5×(23-35)}×125.9=125.7mm

[0024] The resin pipe 6 used in this embodiment preferably has a deflection rate of 5% or less. The deflection rate is preferably measured in accordance with the Japan Water Works Association standard: JWWA K 144 (polyethylene pipe for water distribution).

[0025] As will be described later, when constructing a rehabilitation pipe 2 inside an existing pipe 1, the outer pipe diameter of the resin pipe 6 (rehabilitation pipe 2) must be smaller than the inner pipe diameter of the existing pipe 1. It is desirable that the outer pipe diameter (mm) of the rehabilitation pipe 2 relative to the inner pipe diameter (mm) of the existing pipe 1 satisfy the relationship shown in Table 1 below. Furthermore, when applying this embodiment, there are no particular restrictions on the outer pipe diameter, but it is preferable to apply it to rehabilitation pipes with an outer diameter of 315 mm or less. With a pipe outer diameter within this range, fusion is possible with a small amount of heat and the electric fusion joint can be made compact, making construction easier. The inner diameter of the rehabilitation pipe 2 (plastic pipe 6) is inevitably smaller than the inner diameter of the existing pipe 1. However, considering the current situation at the site where the existing pipe 1 is being rehabilitated, the existing pipe 1 is a pipe that has been in operation for 30 to 50 years. In Japan, the current population is overwhelmingly smaller than the current population 30 to 50 years ago. Considering this, it is generally considered that there are no problems with applying the rehabilitation pipe 2, even if the flow rate is slightly reduced due to the smaller inner diameter of the rehabilitation pipe 2. Here, it is preferable that the diameter reduction ratio, expressed as the relationship (outer diameter of the plastic pipe / inner diameter of the existing pipe), is 35% or less. Maintaining this relationship ensures the largest possible flow rate in the rehabilitation pipe 2.

[0026] [Table 1]

[0027] The nominal diameter (nominal diameter of the resin pipe 6), outer diameter: D, and thickness: t of the rehabilitation pipe 2 can be selected from the sizes shown in Table 2 below. In Table 2, PTC K 03 indicates the Association standard for polyethylene pipe systems for water distribution (politec association standard), and PWA 001 indicates the Association standard for polyethylene pipe systems for building facilities.

[0028] [Table 2]

[0029] The resin pipe 6 preferably has a tensile yield strength of 20 MPa or more, and a tensile elongation at break of 350% or more. The resin pipe 6 preferably has a tensile modulus of 800 to 1100 MPa. The flexural modulus of 1000 to 1200 MPa, and a water pressure breaking strength of 4.0 MPa or more. These specific values ​​can be measured in accordance with the above-mentioned Japan Water Works Association standard: JWWA K 144 (Polyethylene pipe for water distribution). As will be explained later in the method for rehabilitating an existing pipe, during construction, the resin pipe 6 is pulled and moved a predetermined distance along the length of the existing pipe 1 inside the existing pipe 1, so it is preferable to provide a protective layer on the outer peripheral surface of the resin pipe 6 to prevent scratches or the like from being caused on the outer peripheral surface of the resin pipe 6. The protective layer may be provided separately on the outer peripheral surface of the resin pipe 6, may be integrated with it, or may be provided separately by a method such as wrapping it around.

[0030] In the extended resin pipes 6, the fusion joints that fuse together the insertion ports 6b at the ends in the pipe axis direction are formed by the electric fusion joint 30 according to the procedure shown in FIGS. As shown in FIG. 2, the resin pipe 6 has a pipe body 6a and an insertion port 6b. The pipe body 6a is cylindrical. The insertion port 6b extends outward in the axial direction from the end of the pipe body 6a in the axial direction. The insertion port 6b is cylindrical and coaxial with the pipe body 6a. The insertion port 6b has a smaller outer diameter than the pipe body 6a and the same inner diameter as the pipe body 6a. The inner surface of the insertion port 6b is continuous with the inner surface of the pipe body 6a. The end of the piping body 6a on the insertion port 6b side in the pipe axis direction is a stopper portion 6a1 radially outward from the insertion port 6b. The end face of the stopper portion 6a1 on the insertion port 6b side in the pipe axis direction of the piping body 6a is flat and extends perpendicular to the central axis of the piping body 6a and the insertion port 6b.

[0031] The electric fusion joint 30 includes a cylindrical resin pipe body 50 made of the same resin as that constituting the resin pipe 6, and a heating wire (described later) spirally arranged on the inner periphery of the resin pipe body 50. The insertion port 6b of the resin pipe 6 is inserted into the radially inner side of the resin pipe body 50, and therefore the resin pipe body 50 has a length and inner diameter that allow the insertion port 6b of the end of the resin pipe 6 to be joined to be inserted a required length. A stopper portion 6a1 provided at the end of the pipe body 6a of the resin pipe 6 on the insertion port 6b side in the pipe axis direction can abut against the end of the resin pipe body 50 in the pipe axis direction when the insertion port 6b is inserted. The resin pipe main body 50 may have an outer diameter equal to that of the pipe main body 6a of the resin pipe 6. Of course, the outer diameter of either the electrofusion joint 30 or the resin pipe 6 may be larger by several millimeters. In most cases, the outer diameter of the electrofusion joint 30 is slightly smaller than that of the resin pipe 6. Both end faces of the resin pipe main body 50 in the pipe axis direction, which is the direction in which the central axis extends, are flat and extend perpendicular to the pipe axis. The ends of the heating wire spirally arranged on the inner circumferential surface of the resin pipe body 50 are connected to terminals 52 and 57 protruding from the outer circumferential side of the resin pipe body 50 .

[0032] As shown in Figure 2, the first insertion port 6b of the first resin pipe 6 is inserted into a first side of the resin pipe body 50 in the axial direction, and the second insertion port 6b of the second resin pipe 6 is inserted into a second side of the resin pipe body 50 in the axial direction. When the first insertion port 6b of the first resin pipe 6 is inserted into the first side of the resin pipe body 50 in the axial direction, the first stopper portion 6a1 of the end of the pipe body 6a of the first resin pipe 6 on the first insertion port 6b side in the axial direction is abutted against the end of the resin pipe body 50 on the first side in the axial direction. This brings the end face of the resin pipe body 50 on the first side in the axial direction into surface contact with the end face of the first stopper portion 6a1 of the first resin pipe 6 on the first insertion port 6b side in the axial direction. Furthermore, when the second insertion port 6b of the second resin pipe 6 is inserted into the second axial side of the resin pipe main body 50, the second stopper portion 6a1 of the end portion of the pipe main body 6a of the second resin pipe 6 that faces the second insertion port 6b in the axial direction is brought into contact with the end portion of the resin pipe main body 50 that faces the second axial side. This brings the end face of the resin pipe main body 50 on the second axial side into surface contact with the end face of the second stopper portion 6a1 of the second resin pipe 6 that faces the second insertion port 6b in the axial direction.

[0033] In this state, as shown in FIG. 3, the connection wire 34 of the controller 33 for applying current is connected to the terminals 52, 57. Then, while maintaining the first stopper portion 6a1 of the first resin pipe 6 against the first end of the resin pipe main body 50 and the second stopper portion 6a1 of the second resin pipe 6 against the second end of the resin pipe main body 50, the controller 33 applies current to the heating wire to heat it. After applying current for a predetermined time with the required amount of power, the current is stopped and the wire is allowed to cool. This allows the first resin pipe 6 and the second resin pipe 6 to be joined together via the fusion joint created by the electrofusion joint 30. By applying electricity to the heating wire, the inner peripheral surface of the resin pipe body 50 and the outer peripheral surface of the first insertion port 6b of the first resin pipe 6 are mutually fused, and the inner peripheral surface of the resin pipe body 50 and the outer peripheral surface of the second insertion port 6b of the second resin pipe 6 are mutually fused, thereby allowing the first resin pipe 6 and the second resin pipe 6 to be fused together in a manner similar to splicing. Because the interior of the resin pipe body 50 cannot be shown in FIG. 4 , the position of the fused portion 35 formed between the resin pipe body 50 and the resin pipe 6 is indicated by a dotted line. The fused portion 35 is formed with a predetermined width around the entire circumference at the contact point between the outer peripheral surface of the resin pipe 6 and the inner peripheral surface of the resin pipe body 50. When the first resin pipe 6 is properly connected to the electric fusion joint 30, the first stopper portion 6a1 of the pipe body 6a of the first resin pipe 6 abuts against the first end of the resin pipe body 50. When the second resin pipe 6 is properly connected to the electric fusion joint 30, the second stopper portion 6a1 of the pipe body 6a of the second resin pipe 6 comes into contact with the second end of the resin pipe body 50.

[0034] In the above explanation based on FIGS. 2 to 4, the detailed structure of the electrofusion joint 30 was omitted, but the detailed structure shown in FIG. 1 can be adopted for the electrofusion joint 30. The electric fusion joint 30 shown in Fig. 1 has a fusion portion on the inner circumferential surface of a resin pipe body 50 made of thermoplastic resin into which a connecting resin pipe is inserted. The fusion portion is formed by inserting an electric heating wire into a spiral notched groove formed on the inner circumferential surface of the resin pipe body 50. More specifically, the electric fusion joint 30 comprises a resin tube main body 50, a first heating portion 51, first terminals 52, 53, a first indicator 55, a second heating portion 56, second terminals 57, 58, and a second indicator 59.

[0035] The resin pipe body 50 made of a thermoplastic resin is formed into a hollow cylindrical shape. As the thermoplastic resin constituting the resin pipe body 50, it is preferable to use a polyolefin resin similar to that of the resin pipe 6 described above.

[0036] Examples of methods for molding the resin pipe body 50 include extrusion molding and injection molding. In particular, extrusion molding makes it easy to mold the resin pipe body 50 into a long body or a large diameter body. The spigot 6b of one of the resin pipes 6 to be connected is inserted into one end of the resin pipe body 50, and the spigot 6b of the other of the resin pipes 6 to be connected is inserted into the other end of the resin pipe body 50. In the resin pipe body 50, the side into which the spigot 6b of one of the resin pipes 6 is inserted is one fitting socket 50A, and the side into which the spigot 6b of the other of the resin pipes 6 is inserted is the other fitting socket 50B. In this way, the resin pipe body 50 has fitting sockets on both ends in the length direction.

[0037] (First heating part) A first heating portion 51 is provided on the inner peripheral surface of one end 50a of the resin pipe body 50 in the length direction (the inner peripheral surface of one joint socket portion 50A). The first heating portion 51 has a first heating wire 61 inserted into a first notched groove formed in a spiral shape on the inner circumferential surface side of the plastic pipe body 50. The opening portion of the first notched groove may have a spiral shape with the pipe axis of the plastic pipe body 50 as the central axis and the distance from the central axis to the inner circumferential surface as the radius, for example.

[0038] The first terminals 52, 53 are provided on the peripheral surface of one end of the resin pipe main body 50 at a distance from each other in the circumferential direction. The first terminals 52 and 53 are provided to pass current through the first heating wire 61 when electrically fusing the connected resin pipe 6 to the first heating portion 51. For simplicity of illustration in FIG. 1, the wire pull-out hole and the first terminals 52 and 53 are shown in the same positions, but in reality they are formed at positions spaced apart in the circumferential direction of the resin pipe body 50.

[0039] The first indicator 55 is embedded in a first recess 54 provided on the outer peripheral surface of the resin pipe main body 50. The first indicator 55 protrudes radially outward from the first recess 54 during electrofusion, when power is supplied to the first heating wire 61 via the first terminals 52 and 53. The protrusion of the first indicator 55 makes it possible to confirm that the first heating element 51 has been reliably electrofused to the connected resin pipe 6. The first indicator 55 may be formed in a color different from that of the electrofusion joint 30 so that it is easily visible even in dark installation spaces. In this case, the first indicator 55 may be colored by dyeing, printing, imprinting, or the like, and the color may be fluorescent or the like. The first indicator 55 may be molded integrally with the resin pipe main body 50 using the same material, or may be molded integrally with the resin pipe main body 50 using a different material. Alternatively, the first indicator 55 may be formed using a material different from that of the resin pipe main body 50 and attached to the resin pipe main body 50. The first indicator 55 is provided to confirm whether the first heating portion 51 has fused.

[0040] (Second heating part) A second heating portion 56 is provided on the inner peripheral surface of the other end 50b of the resin pipe body 50 in the length direction (the inner peripheral surface of the other joint socket portion 50B). The second heating portion 56 has a second heating wire 62 inserted into a second notched groove formed in a spiral shape on the inner circumferential surface side of the plastic pipe body 50. The opening portion of the second notched groove may have a spiral shape with the pipe axis of the plastic pipe body 50 as the central axis and the distance from the central axis to the inner circumferential surface as the radius, for example. The second heat generating portion 56 is configured in substantially the same manner as the first heat generating portion 51. In this embodiment, the winding direction and number of turns of the spiral formed by the first heating wire 61 and the second heating wire 62 are not particularly limited.

[0041] The second terminals 57, 58 are provided on the peripheral surface of the other end of the resin pipe main body 50 at a distance from each other in the circumferential direction. The second terminals 57 and 58 are provided to pass electricity through the second heating wire 62 when electrically fusing the connected resin pipe 6 to the second heating portion 56. For simplicity of illustration, the wire pull-out holes and the second terminals 57 and 58 are shown in the same positions in FIG. The second indicator 59 is embedded in a second recess 60 provided on the outer peripheral surface of the resin pipe main body 50. The second indicator 59 protrudes radially outward from the second recess 60 during electrofusion, when power is supplied to the second heating wire 62 via the second terminals 57 and 58. The protrusion of the second indicator 59 makes it possible to confirm that the second heating element 56 has been reliably electrofused to the connected resin pipe 6. The second indicator 59 may be formed in a color different from that of the electrofusion joint 30 so that it is easily visible even in dark installation spaces. In this case, the second indicator 59 may be colored by dyeing, printing, imprinting, or the like, and the color may be fluorescent or the like. The second indicator 59 may be molded integrally with the resin pipe main body 50 using the same material, or may be molded integrally with the resin pipe main body 50 using a different material. Alternatively, the second indicator 59 may be formed using a material different from that of the resin pipe main body 50 and attached to the resin pipe main body 50. The second indicator 59 is provided to confirm whether the second heating portion 56 has fused. As described above, the second heat generating portion 56 is configured in substantially the same manner as the first heat generating portion 51.

[0042] The first heating wire 61 and the second heating wire 62 may be made of nichrome, iron-chromium alloy, copper-nickel alloy, copper-manganese alloy, iron-nickel alloy, manganese, copper-nickel-manganese alloy, nickel-chromium alloy, chromel, etc. The first heating wire 61 and the second heating wire 62 may be coated or uncoated. 1, the first heating wire 61 is arranged in a spiral shape with a folded-back portion located toward the center of the length of the resin pipe body 50. Therefore, electricity can be applied to the first heating wire 61 using the first terminals 52 and 53. The second heating wire 62 is arranged in a similar manner, and electricity can be applied to the second heating wire 62 using the second terminals 57 and 58.

[0043] The electrofusion joint 30 shown in FIG. 1 can be applied to the welding process previously described with reference to FIGS. 2 to 4, and can be suitably used when resin pipes 6, 6 are extended, fused, and joined. With this electric fusion joint 30, it is easy to confirm that the fusion joint has been reliably performed by checking the protrusions of the indicators 55, 59, so that the resin pipes 6, 6 can be reliably fusion-joined without causing fusion defects. Therefore, when the existing pipe 1 is rehabilitated using the resin pipe 6 as will be described later, the pipe can be rehabilitated while suppressing poor joints.

[0044] Hereinafter, a method for rehabilitating an existing pipe 1 by forming a rehabilitation pipe 2 shown in FIG. 5 will be described as an example to which the pipe connection structure of the embodiment can be applied. In this case, the electrofusion joint 30 constitutes the rehabilitation pipe 2 that is housed inside the existing pipe 1, similar to the resin pipe 6, as shown in FIG. 5. Here, the pipe connection structure of the embodiment will be described using an example in which it is applied to the rehabilitation pipe 2, but the pipe connection structure of the present invention can of course be applied to pipes other than the rehabilitation pipe 2. For example, the pipe connection structure of the present invention can be effective even in a small space inside a building.

[0045] FIG. 5 shows a cross section of an existing pipe 1 buried underground, and also shows a state in which a new rehabilitation pipe 2 is housed and laid inside the existing pipe 1 along its length. In Fig. 1, an inlet-side pit 3 and an outlet-side pit 4 are formed by excavating the ground at a predetermined interval in the area where the rehabilitation pipe 2 is formed. In addition, in an area other than the area between the inlet-side pit 3 and the outlet-side pit 4, an additional inlet-side pit 5 is formed to the side of the inlet-side pit 3 shown in Fig. 1.

[0046] 5 is a cross-sectional view of the existing pipe 1 at the time when the rehabilitation pipe 2 has been laid inside the existing pipe 1, and the rehabilitation work can be completed by backfilling the inlet-side vertical hole 3, the outlet-side vertical hole 4, and the additional inlet-side vertical hole 5 from the state shown in Fig. 5. After the rehabilitation pipe 2 is placed inside the existing pipe 1, a filler such as mortar may be filled in the gaps within the existing pipe 1, or the rehabilitation work may be completed by backfilling the inlet-side vertical hole 3, the outlet-side vertical hole 4, and the additional inlet-side vertical hole 5 from the state shown in Fig. 1 without filling the gaps. The rehabilitation pipe 2 is configured by joining together a plurality of straight resin pipes 6 (pipes).

[0047] Although the explanation will differ slightly depending on whether the existing pipe 1 is a water pipe, a gas pipe, or a sewer pipe, the following will be given taking as an example a case where the existing pipe 1 is buried underground. Figure 6 shows a state in which only a portion of the existing pipe 1 has already been rehabilitated with a resin pipe 6. Figure 6 is drawn to explain the process of forming a rehabilitation pipe 2 along the entire existing pipe 1 by sequentially joining other resin pipes 6 to the partially rehabilitated resin pipe 6.

[0048] As shown in FIG. 6, an inlet-side pit 3 and an outlet-side pit 4 are formed at a predetermined interval along an existing pipe 1 buried at a predetermined depth in the ground 11 below the ground 10. Regarding the installation environment of the existing pipe 1, it is difficult to excavate a wide area along the existing pipe 1, but if the environment allows for the formation of an inlet side vertical hole 3 and an outlet side vertical hole 4 that reach the ground at intervals in the ground 11 along the existing pipe 1 as shown in Figure 6, the pipeline rehabilitation method described below can be applied. In addition, when the existing pipe 1 is a sewer pipe, adjacent manholes among a plurality of manholes formed at predetermined intervals along the sewer pipe may be used as the inlet shaft 3 or the outlet shaft 4.

[0049] As shown in FIG. 6, the outlet-side pit 4 is formed to include the resin pipe 6 located at the end of the area that has already been rehabilitated with the resin pipe 6. As an example, when the rehabilitated resin pipe 6 is viewed from above, the insertion port 6b is formed to reach the existing pipe 1 from the ground 10 so that it is located a sufficient length inside the outlet-side pit 4. In addition, an outlet-side access port 1a is formed in the existing pipe 1 below the outlet-side pit 4 so that it communicates with the outlet-side pit 4 and the interior of the existing pipe 1. By forming the outlet-side access port 1a in the peripheral wall of the existing pipe 1, the outlet-side pit 4 and the interior of the existing pipe 1 are communicated with each other. Additionally, an inlet-side pit 3 is formed at a position a predetermined distance away from the outlet-side pit 4 along the existing pipe 1. The inlet-side pit 3 is formed so as to reach from the ground 10 to the existing pipe 1 below. It is preferable that the inner diameter of the inlet-side pit 3 is approximately the same as or slightly larger than the outlet-side pit 4. Once the inlet-side pit 3 is formed, an inlet-side access port 1b is formed in the existing pipe 1 below it so as to connect the inlet-side pit 3 to the interior of the existing pipe 1. By forming the inlet-side access port 1b in the peripheral wall of the existing pipe 1, the inlet-side pit 3 and the interior of the existing pipe 1 are connected. The inner diameter of the inlet side pit 3 can be slightly larger than the length of one resin pipe 6. If there is sufficient free space in the installation environment of the existing pipe 1 at the position where the inlet side pit 3 is to be formed, the inner diameter of the inlet side pit 3 may be formed larger.

[0050] After the inlet side vertical hole 3 is formed, for example, two resin pipes 6 are inserted into the existing pipe 1 through the inlet side vertical hole 3. The length of the resin pipes 6 used here is set to a length that allows them to be inserted into the existing pipe 1 through the inlet side vertical hole 3 and the inlet side access port 1b. When inserting two resin pipes 6 into an existing pipe 1, it is preferable to adjust the position of the resin pipes 6 along the internal space of the existing pipe 1 as shown in FIG. 7 and accommodate them so that the insertion ports 6b of the two resin pipes 6 are positioned toward the center of the inlet-side vertical hole 3. After aligning the insertion ports 6b of the two resin pipes 6, as shown in FIG. 7, the insertion ports 6b of the two resin pipes 6 are positioned facing each other using a support 13 such as a stand required for fusion. Thereafter, the two resin pipes 6 are fused using an electrofusion joint 30 according to the fusion procedure previously described with reference to FIGS. 2 to 4. By fusion, the two resin pipes 6 are joined in a spliced ​​state via the electrofusion joint 30 as shown in FIG.

[0051] Once the two resin pipes 6 have been fused, the two resin pipes 6 are slid from the inlet side shaft 3 to the outlet side shaft 4. The leading resin pipe 6 is moved to a position close to the outlet side shaft 4, and the two resin pipes 6 are slid along the existing pipe 1 so that the end (rear end) 6c ​​of the rear resin pipe 6 is positioned toward the center of the inlet side shaft 3.

[0052] Thereafter, new resin pipe 6 is again introduced into existing pipe 1 through inlet-side vertical hole 3. Then, the newly introduced resin pipe 6 is fused to the rear end of the previously fused rear-end side resin pipe 6 according to the fusion procedure using electric fusion joint 30 previously described with reference to Figures 2 to 4. As a result, multiple resin pipes 6 are introduced and joined into existing pipe 1, for example, as shown in Figure 9. In the manner described above, new resin pipes 6 are successively introduced from the inlet shaft 3 into the interior of the existing pipe 1, and the fused resin pipes 6 are successively fed out toward the outlet shaft 4. Each time a new resin pipe 6 is fed out, it is fused below the inlet shaft 3, and multiple resin pipes 6 fused via electric fusion joints 30 can be continuously installed inside the existing pipe 1 from the outlet shaft 4 to the inlet shaft 3.

[0053] FIG. 8 shows a drawing device H suitable for use when sliding a plurality of resin pipes 6 connected together within an existing pipe 1. In FIG. The lead-in device H shown in Fig. 8 includes a winch device 20 housed in the outlet-side vertical shaft 4 and a lead-in wire (wire) 22 of a predetermined length wound around a winding drum 21 of the winch device 20. The tip end of the lead-in wire 22 is connected to the leading resin pipe 6 in the resin pipes 6 that are connected together by welding. In the rehabilitation work of the existing pipe 1, for example, after the outlet-side vertical shaft 4 and the inlet-side vertical shaft 3 are formed, the winch device 20 is installed at the bottom side of the outlet-side vertical shaft 4. Then, the lead-in wire 22 of the winch device 20 is pulled out from the winding drum 21 until the tip of the lead-in wire 22 reaches the lower side of the inlet-side vertical shaft 3, and the tip of the lead-in wire 22 is attached to the leading resin pipe 6 to be connected to the top of multiple pieces of resin pipe 6. When connecting multiple pieces of resin pipe 6 to the top of the existing pipe 1, the lead-in wire 22 of the winch device 20 is pulled by the lead-in wire 22 while sliding it within the existing pipe 1, and the connected resin pipe 6 can be easily moved along the existing pipe 1.

[0054] When the leading resin pipe 6 that was fused first reaches the resin pipe 6 in the outlet-side vertical hole 4 as shown in Figure 10, the insertion ports 6b of the two adjacent resin pipes 6 are made to face each other. In this state, using a support 13 or the like, the insertion ports 6b of the two resin pipes 6 located below the outlet-side vertical hole 4 are positioned so that they face each other. Thereafter, the two adjacent resin pipes 6 below the outlet-side vertical hole 4 are fused according to the fusion procedure using the electrofusion joint 30 previously described with reference to Figures 2 to 4. By the above work, the pipe renewal work using a plurality of resin pipes 6 for the existing pipe 1 between the inlet side vertical hole 3 and the outlet side vertical hole 4 can be completed.

[0055] Once the pipeline rehabilitation work for the existing pipe 1 has been completed by extending and connecting multiple resin pipes 6 from the position of the outlet-side vertical hole 4 to the position of the inlet-side vertical hole 3, the pipeline rehabilitation work for the remaining area is carried out. That is, the pipeline rehabilitation work for the area to the right of the inlet-side vertical hole 3 shown in Figure 10 is carried out. To achieve this, an additional entrance-side pit 5 and an additional entrance-side work opening 1c are formed not between the exit-side pit 4 and the entrance-side pit 3, but at a position spaced apart on the opposite side of the exit-side pit 4 from the entrance-side pit 3 (to the side of the entrance-side pit 3 in Figure 10). The work so far has involved introducing a resin pipe 6 starting from the inlet vertical shaft 3 toward the outlet vertical shaft 4, thereby rehabilitating the existing pipe 1. In the next step, an additional entrance-side pit 5 is formed at a position opposite to the side facing the exit-side pit 4 from the entrance-side pit 3 that was previously used as the starting point, and at a predetermined distance from the entrance-side pit 3 that was used as the starting point.

[0056] 6 shown above shows a state in which an additional inlet-side shaft 5 has been formed in advance in the early stages of the rehabilitation work at a position spaced apart from the inlet-side shaft 3. The additional inlet-side shaft 5 may be formed in the early stages of the rehabilitation work, or after all of the resin piping 6 has been laid between the inlet-side shaft 3 and the outlet-side shaft 4 as shown in FIG. 10, or during the intermediate stage in which the resin piping 6 is being extended and connected between the inlet-side shaft 3 and the outlet-side shaft 4. In the work up to now, the resin pipe 6 has been installed by sequentially extending it from the inlet side vertical hole 3 as the starting point toward the outlet side vertical hole 4, but in the work that follows, it will be necessary to install the resin pipe 6 between the additional inlet side vertical hole 5 and the inlet side vertical hole 3 that was previously used as the starting point.

[0057] In the subsequent work, the inlet-side shaft 3, which was the starting point earlier, is regarded as the outlet-side shaft, and multiple resin pipes 6 are sequentially introduced into the existing pipe 1 from the additional inlet-side shaft 5. Then, the multiple resin pipes 6 are spliced ​​and connected below the additional inlet-side shaft 5, and are sequentially sent toward the inlet-side shaft 3. When the head of the spliced ​​resin pipe 6 reaches the resin pipe 6 below the inlet-side shaft 3, the ends of the resin pipes 6, 6 that have reached and are facing each other are fused together, as previously explained with reference to Figure 10. By these work steps, multiple resin pipes 6 can be placed between the bottom of the additional inlet-side shaft 5 and the inlet-side shaft 3, and the pipeline rehabilitation of the existing pipe 1 in this area is completed. As explained above, by forming additional inlet side pits 5 sequentially and intermittently along the length of the existing pipe 1, the entire pipe line can be rehabilitated for the corresponding length of the existing pipe 1. Even if the site does not allow for wide-area excavation along the existing pipe 1, the rehabilitation pipe 2 can be installed without any problems if the site allows for the formation of an inlet side vertical hole 3 and an outlet side vertical hole 4, or an additional inlet side vertical hole 5 in addition to these.

[0058] 1 to 10, the existing pipe 1 is long. However, if the existing pipe 1 is relatively short, this can be achieved by providing an outlet-side pit 4 at one longitudinal end of the existing pipe 1 to be rehabilitated, and an inlet-side pit 3 at the other longitudinal end. In this case, resin pipes 6 are sequentially introduced from the inlet-side pit 3 to extend and connect the resin pipes 6, and when the tip of the extended resin pipe 6 reaches the outlet-side pit 4, the rehabilitation work for the existing pipe 1 is completed. It is also possible that the direction of a sewer pipe changes at the location of a manhole. In this case, an outlet shaft 4 or an inlet shaft 3 can be formed at the location of one manhole, and an inlet shaft 3 or an outlet shaft 4 can be formed at the location of another manhole. Therefore, the rehabilitation work for existing pipes described above can also be applied to the rehabilitation of existing pipes that have a bent route via a manhole.

[0059] As described above, according to the pipe connection structure of this embodiment, the insertion port 6b extending from the end of the pipe body 6a of the resin pipe 6 in the pipe axis direction is inserted into the electrofusion joint 30, the stopper portion 6a1 at the end of the pipe body 6a in the pipe axis direction is abutted against the end of the electrofusion joint 30 in the pipe axis direction, and electricity is passed through the electrofusion joint 30 to connect the resin pipe 6 and the electrofusion joint 30. If the insertion port 6b is inserted into the electrofusion joint 30 by an appropriate length, the stopper portion 6a1 of the pipe body 6a and the end of the electrofusion joint 30 will be in abutting state after connection, and this can be visually confirmed to confirm that the connection is correct. This eliminates the need for tedious tasks such as marking a reference line for confirmation, thereby improving workability. Furthermore, since marking a reference line is not required, there is no need for tedious tasks such as redoing the work due to forgetting to mark a reference line, which also improves workability. Furthermore, since the insertion port 6b extending from the pipe body 6a of the pipe 6 is inserted into the electric fusion joint 30 and the stopper portion 6a1 at the end of the pipe body 6a in the pipe axis direction is abutted against the end of the electric fusion joint 30, the amount of radial outward protrusion of the electric fusion joint 30 from the pipe body 6a can be reduced, and the electric fusion joint 30 can be prevented from hindering installation, which also makes it possible to improve installation ease. In addition, since the stopper portion 6a1 at the end of the pipe body 6a of the pipe 6 in the pipe axis direction is abutted against the end of the electric fusion joint 30, the gap opening to the outer periphery between the end of the pipe body 6a of the resin pipe 6 in the pipe axis direction and the end of the electric fusion joint 30 in the pipe axis direction can be reduced, making it possible to prevent dirt from adhering to this gap.

[0060] Furthermore, according to the piping connection structure of this embodiment, the outer diameter of the plastic pipe body 50 of the electric fusion joint 30 is the same as the outer diameter of the piping body 6a of the resin piping 6, so the amount of radial outward protrusion of the plastic pipe body 50 of the electric fusion joint 30 from the piping body 6a can be eliminated, which further prevents the electric fusion joint 30 from hindering installation and further improves installation ease.

[0061] Furthermore, according to the piping connection structure of this embodiment, a rehabilitation piping 2 is constructed to be housed inside the existing piping 1, and by suppressing the amount of radial outward protrusion of the electric fusion joint 30 from the piping main body 6a, it is possible to suppress the electric fusion joint 30 from getting caught on other parts when moving within the existing piping 1, thereby preventing construction from being hindered, and further improving construction ease.

[0062] The existing pipe 1 and the rehabilitation pipe 2 described above are both described as examples of pipes that are buried underground, but the pipe connection structure of the present invention can also be applied to cases where the existing pipe 1 is not underground but is installed under a structure or along a bridge, etc. Furthermore, the pipe connection structure of the present invention can also be applied to pipes other than the rehabilitation pipe 2 that are housed within the existing pipe 1. [Explanation of symbols]

[0063] 1...existing pipe, 2...rehabilitation pipe, 6...resin pipe (pipe), 6a...pipe body, 6a1...stopper portion, 6b...insertion port, 30...electric fusion joint.

Claims

1. an electric fusion joint; a pipe having a pipe body and a spigot extending from an end of the pipe body in the pipe axis direction and inserted into the electric fusion joint; Equipped with A pipe connection structure, wherein a stopper portion is provided at an end portion of the pipe body in the pipe axis direction, the stopper portion being able to abut against the end portion of the electric fusion joint in the pipe axis direction.

2. 2. The pipe connection structure according to claim 1, wherein an outer diameter of the electrofusion joint is equal to an outer diameter of the pipe body.

3. 3. The pipe connection structure according to claim 1, wherein the electric fusion joint and the pipe constitute a rehabilitation pipe housed inside an existing pipe.

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