Electric fusion joint and pipe installation method using electric fusion joint

Abstract

To provide an electric fusion joint, and a pipe installation method using the electric fusion joint.SOLUTION: An electric fusion joint according to the present invention has a heating wire arranged on an inner peripheral part of a thermoplastic resin pipe body into which a resin pipe to be connected is inserted, where a portion where the heating wire is provided is a fusion part. The electric fusion joint comprises an annular body that is provided on an outer peripheral surface of the resin pipe body and is in contact with an outer peripheral surface of the resin pipe body at a position of overlapping with a heating wire arrangement area where the heating wire is provided along a length direction of the resin pipe body.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electric fusion joint and a piping construction method using the electric fusion joint. [Background technology]

[0002] Conventionally, for example, an electric fusion joint is known, as described in Patent Document 1. This electric fusion joint has a fusion part in which an electric heating wire is inserted into a notched groove formed in a spiral shape on the inner peripheral surface of a thermoplastic resin pipe into which a connecting resin pipe is inserted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4527278 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electric fusion joint, wires can be easily laid in large-diameter plastic pipes, but in the case of large diameters, a large amount of heat must be applied during fusion, and the inner diameter of the joint pipe increases due to thermal expansion. If the inner diameter of a large-diameter joint pipe increases, the clearance between the joint pipe and the connected plastic pipe increases, which may cause poor fusion. In addition, large-diameter electric fusion joints are heavy, so if the joint thickness is reduced beyond a certain level in order to reduce the weight even a little, the aforementioned fusion failure is likely to occur. This is because the stiffness of the joint pipe decreases when the joint pipe is made thinner, making it more likely to expand and widen. For this reason, it has been difficult to reduce the wall thickness of large-diameter joint pipes.

[0005] In view of the above-mentioned circumstances, the present invention aims to provide an electric fusion joint that has a configuration that can increase rigidity and suppress thermal expansion during fusion even in the case of a large diameter, thereby enabling reliable fusion, and a piping construction method using an electric fusion joint. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following aspects. The electric fusion joint of this embodiment is an electric fusion joint having an electric heating wire arranged on the inner periphery of a thermoplastic resin pipe body into which a connecting plastic pipe is inserted, the portion where the electric heating wire is provided being the fusion portion, and is characterized in that it has an annular body that contacts the outer periphery of the resin pipe body at a position on the outer periphery of the resin pipe body that overlaps with the electric heating wire arrangement area where the electric heating wire is arranged along the longitudinal direction of the resin pipe body.

[0007] The plastic pipe to be connected is inserted into the plastic pipe body of the electric fusion joint, and the inner periphery of the plastic pipe body is heated by passing an electric current through the heating wire, thereby fusing the plastic pipe to the inside of the plastic pipe body. When electricity is passed through the heating wire to heat the inner periphery of the plastic pipe body to a degree that allows it to be fused to the plastic pipe, the plastic pipe body tends to thermally expand. However, the annular body present on the outer periphery of the plastic pipe body suppresses the thermal expansion of the plastic pipe body, so the increase in the clearance that occurs between the inner periphery of the plastic pipe body and the outer periphery of the plastic pipe is suppressed. Therefore, even if electricity is passed through the heating wire and the fusion operation is performed, there will be no fusion failure due to the thermal expansion of the plastic pipe body. In particular, even if the plastic pipe body and the plastic pipe are large in diameter, the aforementioned increase in clearance can be suppressed, so that the large-diameter plastic pipe body and the plastic pipe can be reliably fused without the occurrence of fusion failures. Effect of the Invention

[0008] The electric fusion joint according to the present invention can reliably fusion-join a plastic pipe body and a plastic pipe without causing any defective welds. Furthermore, the electric fusion joint can electrically fusion-join a plastic pipe body and a plastic pipe having a large diameter without causing any defective welds. [Brief description of the drawings]

[0009] [Figure 1] 1 is a side view showing an electric fusion joint of a first embodiment according to the present invention. [Diagram 2]FIG. 4 is a side cross-sectional view showing a state in which a plastic pipe is being fused using the electric fusion joint. [Diagram 3] FIG. 4 is a side view showing an electric fusion joint according to a second embodiment of the present invention. [Figure 4] FIG. 13 is a partial cross-sectional view showing the state in which a metal band remains after the electric fusion joint and the plastic pipe have been electrically fused together. [Diagram 5] FIG. 4 is a side view showing a suitable jig for use when fusing a large-diameter plastic pipe body and a plastic pipe. [Figure 6] FIG. 11 is a side view showing an electric fusion joint according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, a first embodiment of an electric fusion joint and a piping construction method using an electric fusion joint according to the present invention will be described with reference to Figs. 1 to 4. "First embodiment" <Electric fusion joint> As shown in Fig. 1, the electric fusion joint 1 of the first embodiment has a fusion part on the inner peripheral surface of a resin pipe body made of thermoplastic resin into which a connecting resin pipe is inserted. The fusion part is formed by inserting an electric heating wire into a spiral notch groove formed on the inner peripheral surface of the resin pipe body. Specifically, the electric fusion joint 1 has a resin pipe body 10, a first fusion part 20, first terminals 30, 31, a first indicator 40, a second fusion part 50, second terminals 60, 61, a second indicator 70, and annular bodies 90, 91 provided to contact the outer peripheral surface of the resin pipe body 10.

[0011] The resin pipe body 10 made of a thermoplastic resin is formed into a hollow cylindrical shape. Examples of the thermoplastic resin constituting the resin pipe body 10 include polyolefin resin, polyvinyl chloride, thermoplastic polyester (thermoplastic polyethylene terephthalate, etc.). Among them, polyolefin resin is preferable as the thermoplastic resin constituting the resin pipe body 10 from the viewpoint of further improving earthquake resistance and durability. Olefin resin pipes have a higher tensile breaking elongation measured according to JIS K 6815-1 and JIS K 6815-3 than rigid polyvinyl chloride pipes. The tensile breaking elongation of rigid polyvinyl chloride pipes is 50 to 150%, while the tensile breaking elongation of olefin resin pipes is 350% or more. In particular, by the extrapolation method specified in ISO / TR9080, high-density polyethylene pipes (PE100) have a tensile breaking elongation of 500% or more, which can better prevent damage caused by earthquakes. The polyolefin resin is not particularly limited, but examples thereof include polypropylene, polybutene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, poly-α-olefin, and the like.

[0012] The specific gravity of the thermoplastic resin is not particularly limited, but is, for example, 942 to 953 kg / m 3 The specific heat of the thermoplastic resin is not particularly limited, but is, for example, 1.9 to 2.3 kJ / kg·[K]. The thermal conductivity of the thermoplastic resin is not particularly limited, but is, for example, 0.46 to 0.5 W / m·K. The thermoplastic resin may be a composition containing additives such as pigments, ultraviolet absorbers, antioxidants, lubricants, etc. The melting point of the thermoplastic resin (i.e., the melting temperature of the resin pipe body 10) is not particularly limited, but is preferably 125 to 260°C, more preferably 125 to 150°C. The plastic pipe body 10 may have a multi-layer structure having a surface layer on at least one of the outer and inner surfaces. For example, by having a surface layer containing an ethylene-vinyl alcohol copolymer resin, the plastic pipe body 10 is more suitable for air conditioning, hot water supply, gas, or fuel. This is because the surface layer containing an 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.

[0013] The surface layer may include, 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 includes these fibers, the tensile strength of the resin pipe body 10 can be increased and thermal expansion can be further suppressed. The surface layer may also include a fluororesin. When the surface layer includes fluorine, resistance (chemical resistance) to acids, alkalis, and the like can be increased. In addition, a layer similar to the above surface layer may be provided inside the peripheral wall of the resin pipe body 10.

[0014] Methods for molding the plastic pipe body 10 include extrusion molding and injection molding. In particular, extrusion molding is easy to mold the plastic pipe body 10 into a long length or a large diameter. Therefore, for example, when the length of the plastic pipe body 10 in the pipe axis O direction is 2 m or more, or when the outer diameter of the plastic pipe body 10 is a large diameter such as 500 mm or more, it is preferable to mold the plastic pipe body 10 by extrusion molding. In addition, in the case of extrusion molding, the inner diameter of the molded plastic pipe body 10 is the same from one end to the other end of the plastic pipe body 10, so that the inner surface cutting (dimensioning) process when manufacturing the electric fusion joint 1 can be omitted and the amount of resin discarded due to the inner surface cutting process can be reduced.

[0015] In particular, when manufacturing a large-diameter electric fusion joint 1 with an outer diameter of 500 mm or more, which is difficult to mold by injection molding, a long plastic pipe with an outer diameter of 500 mm or more and a length of 2 m or more can be molded by extrusion molding, cut the long plastic pipe to an appropriate length, and provide a fusion portion on the inner surface to form the electric fusion joint 1. Also, one end of the long plastic pipe may be enlarged to form a socket, thereby manufacturing an electric fusion joint 1 with a length of 2 m or more, which is difficult to mold by injection molding. In the case of a large diameter of 500 mm or more, the ratio D / T of the outer diameter (nominal diameter D) of the plastic pipe body 10 to the thickness of the plastic pipe body 10 (maximum thickness of the fused portion: T) is preferably, for example, 8.5 times or more and 10 times or less in the case of an SDR11 pipe. If the D / T value is less than 8.5 times, the purpose of providing the annular bodies 90, 91 to reinforce the plastic pipe body 10 becomes weak. If the D / T value exceeds 10 times, the strength of the plastic pipe body 10 may become significantly inferior to the strength of the plastic pipes 80, 81.

[0016] The electric fusion joint 1 has a plastic pipe body 10, which has a first plastic pipe section 11 and a second plastic pipe section 12. The first plastic pipe section 11 and the second plastic pipe section 12 are provided along the direction of the pipe axis O of the plastic pipe body 10. Hereinafter, the direction along the pipe axis O of the plastic pipe body 10 may be abbreviated as the "length direction of the pipe." Also, the direction perpendicular to the pipe axis O may be abbreviated as the "radial direction." Furthermore, the circumferential direction of the plastic pipe body 10 may be abbreviated as the "circumferential direction."

[0017] The first resin pipe section 11 is provided at one end in the longitudinal direction of the resin pipe body 10. The second resin pipe section 12 is provided at the other end in the longitudinal direction of the resin pipe body 10. The first resin pipe section 11 and the second resin pipe section 12 have the same inner diameter and the same outer diameter. A first resin pipe 80 as a connecting resin pipe is inserted from one end in the longitudinal direction of the first resin pipe section 11. A second resin pipe 81 as a connecting resin pipe is inserted from the other end in the longitudinal direction of the second resin pipe section 12. Both the first resin pipe section 11 and the second resin pipe section 12 function as receiving ports.

[0018] However, the plastic pipe body 10 is not limited to the above-mentioned form (so-called increaser or reducer). For example, the plastic pipe body 10 may be bent in the center in the length direction, and may be a so-called elbow. For example, the plastic pipe body 10 may have a branch pipe, and may be a so-called Tee. For example, the plastic pipe body 10 may be long enough to be usable not only as a simple joint but also as a general pipe material. Such a plastic pipe body 10 may be a pipe material in which only the pipe end is expanded in diameter. More specifically, a pipe material in which one end is expanded in diameter and serves as a socket provided with the first fusion part 20, and the other end is a spigot to be inserted into the socket of another pipe material, and the distance between the socket and the spigot (between one end and the other end) is a long plastic pipe, for example, 2 m or more.

[0019] (1st fusion part) A first fusion portion 20 is provided on the inner peripheral surface 11a of the first resin pipe section 11. That is, the first fusion portion 20 is provided on one end side of the resin pipe body 10 in the longitudinal direction of the pipe. In the first fusion portion 20, a first heating wire 21 is inserted into a first notched groove formed in a spiral shape on the inner peripheral surface 11a of the first resin pipe section 11. The opening portion of the first notched groove that opens into the inner peripheral surface 11a of the first resin pipe section 11 may have a spiral shape with the pipe axis O as the central axis and the distance from the central axis to the inner peripheral surface 11a as the radius, for example.

[0020] The first terminals 30, 31 are provided at intervals in the circumferential direction in the vicinity 11b of the end of the socket in the first resin pipe section 11. The first terminal 30 is disposed in the first wire outlet hole 33 and connected to one end of the first heating wire 21. The first terminal 31 is disposed in the first wire outlet hole 34 and connected to the other end of the first heating wire 21. The first wire outlet holes 33, 34 are provided in the first resin pipe section 11 so as to be spaced apart in the radial direction in the vicinity 11b of the end of the socket and to penetrate the first resin pipe section 11. The first terminals 30, 31 are provided to pass electricity through the first heating wire 21 when the first resin pipe 80 to be connected is electrically fused to the first fusion section 20. In FIG. 1, for the sake of simplicity, the first wire outlet holes 33, 34 and the first terminals 30, 31 are shown in the same positions.

[0021] The first indicator 40 is embedded in, for example, a first recess 41 provided on the outer circumferential surface 11c of the first resin pipe portion 11. The first indicator 40 protrudes radially outward from the first recess 41 during electrical fusion to supply power to the first heating wire 21 via the first terminals 30, 31. The protrusion of the first indicator 40 allows confirmation that the first fusion portion 20 has been electrically fused to the first resin pipe 80 to be connected. The first indicator 40 is for confirming electrical fusion.

[0022] The first indicator 40 may be molded integrally with the plastic pipe body 10 using the same material, or may be formed using a material different from that of the plastic pipe body 10 and assembled to the plastic pipe body 10. When the first indicator 40 is molded integrally with the plastic pipe main body 10 using the same material, for example, the first indicator 40 and the first recess 41 can be simultaneously post-machined on the plastic pipe main body 10. Specifically, the first recess 41 may be cut (bored) with a drill or the like while leaving the portion that will become the first indicator 40 so that the portion that will become the first indicator 40 remains in the first recess 41, and the first indicator 40 and the first recess 41 may be molded on the plastic pipe main body 10 at the same time.

[0023] (Second fused part) A second fusion section 50 is provided on the inner circumferential surface 12a of the second resin pipe section 12. The second fusion section 50 is provided on the other end side in the longitudinal direction of the pipe in the electric fusion joint 1. In the second fusion section 50, a second heating wire 51 is inserted into a second notched groove formed in a spiral shape on the inner circumferential surface 12a of the second resin pipe section 12. The opening portion of the second notched groove that opens on the inner circumferential surface 12a of the second resin pipe section 12 may be, for example, in a spiral shape with the pipe axis O as the central axis and the distance from the central axis to the inner circumferential surface 12a as the radius.

[0024] The second fused portion 50 is configured substantially similarly to the first fused portion 20 . In this embodiment, the winding direction and the number of turns of the spiral formed by the first heating wire 21 and the second heating wire 51 are not particularly limited. For example, if the winding direction is right-handed when viewed from the opening side of one of the sockets in the electric fusion joint 1, it will be left-handed when viewed from the opening side of the other socket. That is, the winding direction is right-handed or left-handed when viewed from the opening side of one of the sockets in the electric fusion joint 1, and when viewed from the opening side of the other socket, it will be opposite to the winding direction when viewed from one socket.

[0025] Here, the winding direction (hereinafter also referred to as the first winding direction) of the first heating wire 21 as viewed from the opening side of the first resin pipe section 11 (the opening side of one of the receiving ports) and the winding direction (hereinafter also referred to as the second winding direction) of the second heating wire 51 as viewed from the opening side of the second resin pipe section 12 (the opening side of the other receiving port) may be the same or different. For example, the first winding direction and the second winding direction may be common to right-handed winding or common to left-handed winding. Furthermore, one of the first winding direction and the second winding direction may be right-handed winding and the other may be left-handed winding.

[0026] In this embodiment, an example in which the first fusion part 20 is provided on one end side of the electric fusion joint 1 and the second fusion part 50 is provided on the other end side of the electric fusion joint 1 will be described, but the present invention is not limited to this. As another example, a fusion part may be provided on at least one end side of the electric fusion joint 1. Here, when the fusion portion is only on one end (the socket portion) side, the winding direction of the heating wire may be clockwise or counterclockwise when viewed from the opening side of the socket portion.

[0027] The second terminals 60, 61 are provided in the second resin pipe section 12 at intervals in the circumferential direction near the end 12b of the receiving portion. The second terminal 60 is connected to one end of the second heating wire 51 through a second wire outlet hole 63. The second terminal 61 is connected to the other end of the second heating wire 51 through a second wire outlet hole 64. The second wire outlet holes 63, 64 are passed through the second resin pipe section 12 in the radial direction near the end 12b of the receiving portion. The second terminals 60, 61 are provided to pass electricity through the second heating wire 51 when the second resin pipe 81 to be connected is electrically fused to the second fusion section 50. The second terminals 60, 61 are configured in a manner substantially similar to the first terminals 30, 31. In FIG. 1, for the sake of simplicity, the second wire withdrawal holes 63, 64 and the second terminals 60, 61 are shown in the same positions, but in reality they are formed so as to be spaced apart in the circumferential direction of the second resin tube portion 12.

[0028] The second indicator 70 is embedded in, for example, a second recess 71 provided on the outer circumferential surface 12c of the second resin pipe portion 12. The second indicator 70 protrudes radially outward from the second recess 71 during electrical fusion to supply power to the second heating wire 51 via the second terminals 60, 61. The protrusion of the second indicator 70 makes it possible to confirm that the second fusion portion 50 has been electrically fused to the second resin pipe 81 that is the connection partner. The second indicator 70 may be molded integrally with the plastic pipe body 10 using the same material, or if it is made of a material different from that of the plastic pipe body 10, it may be attached to the plastic pipe body 10. The second indicator 70 is configured in substantially the same manner as the first indicator 40. The second indicator 70 is for confirming electrical fusion.

[0029] As described above, the second fusion portion 50 is configured substantially similarly to the first fusion portion 20. The second terminals 60, 61 are configured substantially similarly to the first terminals 30, 31. The second indicator 70 is configured substantially similarly to the first indicator 40. Therefore, hereinafter, the resin pipe main body 10, the first fusion portion 20, the first terminals 30, 31, and the first indicator 40 will be described in detail, and explanations of the structures of other parts that have a common structure will be omitted as appropriate. In this embodiment, both the first fusion portion 20 and the second fusion portion 50 are provided, but only one of the first fusion portion 20 and the second fusion portion 50 may be provided. That is, the electric fusion joint 1 may have a configuration in which only one end can be electrically fused.

[0030] The first heating wire 21 and the second heating wire 51 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 21 and the second heating wire 51 may be coated or uncoated. (Terminal) In the first resin pipe section 11, first wire drawing holes 33, 34 and first terminals 30, 31 are provided at intervals in the circumferential direction near the end 11b of the receiving section, and these are connected to the first heating wire 21. Although not shown in FIG. 1, the first heating wire 21 is arranged in a spiral shape so as to have a folded-back portion at a position toward the center in the longitudinal direction of the resin pipe body 10. Therefore, electricity can be passed through the first heating wire 21 using the first terminals 30, 31. The second heating wire 51 is arranged in a similar manner, and electricity can be passed through the second heating wire 51 using the second terminals 60, 61.

[0031] (Indicator position) The first indicator 40 is disposed on the end surface 11d side of the first resin pipe section 11 from the center position E01 of the width E1 of the arrangement region (electric heating wire arrangement region) of the first heating wire 21 along the length direction of the resin pipe body 10 where the first fusion portion 20 is provided. Here, the width E1 of the electric heating wire arrangement region along the length direction of the resin pipe body 10 refers to the width in the length direction of the resin pipe body 10 where the first heating wire 21 provided in the length direction of the resin pipe body 10 exists from one end to the other end. The center position E01 of the width E1 refers to the center position in the length direction of the pipe in the width E1. The width E1 can be expressed as the width of the arrangement region of the first heating wire 21 along the length direction of the resin pipe body 10. The center position E01 can also be expressed as the center position of the electric heating wire arrangement region (arrangement region of the first heating wire 21) along the length direction of the pipe.

[0032] The second indicator 70 is disposed on the end surface 12d side of the second resin pipe section 12 from the center position E02 of the width E2 of the arrangement region (electric heating wire arrangement region) of the second heating wire 51 along the length direction of the resin pipe body 10 where the second fusion portion 50 is provided. Here, the width E2 of the electric heating wire arrangement region along the length direction of the resin pipe body 10 refers to the width in the length direction of the resin pipe body 10 where the second heating wire 51 provided in the length direction of the resin pipe body 10 exists from one end to the other end. The center position E02 of the width E2 refers to the center position in the length direction of the pipe in the width E2. The width E2 can be expressed as the width of the arrangement region of the first heating wire 21 along the length direction of the resin pipe body 10. The center position E02 can also be expressed as the center position of the electric heating wire arrangement region (arrangement region of the second heating wire 51) along the length direction of the pipe.

[0033] On the outer periphery of the first resin pipe section 11, a ring-shaped body 90 made of a metal band is provided so as to overlap the arrangement area of ​​the first heating wire 21 and pass through the center position E01 of the width E1 of the arrangement area of ​​the heating wire. The metal material constituting the ring-shaped body 90 is made of either a steel material such as stainless steel or aluminum. However, it is necessary to select a metal material having a strength sufficient to suppress an increase in the diameter of the first resin pipe section 11 during fusion, which will be described later. For example, the breaking strength of the ring-shaped body 90 is preferably 1 ton or more. In the case of a metal band, a metal band made of stainless steel can be adopted in consideration of corrosion resistance and strength. In the case of the ring-shaped body 90 made of a metal band, the thickness can be 0.3 mm or more and 2.5 mm or less. In the case of a metal band, if it is made of a weldable metal, it may be welded to form the ring-shaped body. Alternatively, a ring having a larger outer diameter than the resin pipe main body 10 may be inserted onto the resin pipe main body 10 and then crimped at a predetermined position to form the ring-shaped body.

[0034] As an example, the annular body 90 is in the shape of a ring made of a metal band, and the outer diameter of the first resin pipe section 11 and the inner diameter of the annular body 90 are equal or nearly equal. The annular body 90 has an inner diameter that allows it to be fitted around the outer periphery of the first resin pipe section 11 without any gaps, or it has an inner diameter that allows it to be loosely fitted into the outer periphery of the first resin pipe section 11, or it to be fitted so as to bite into the outer periphery of the first resin pipe section 11, or it has an inner diameter that allows it to be embedded in the outer periphery. In any case, the annular body 90 may have a shape that allows it to be placed in contact with the outer periphery of the first resin pipe section 11.

[0035] The width E3 of the annular body 90 is preferably 30 mm or more (positional width) in order to suppress an increase in the diameter of the first resin pipe portion 11 during thermal expansion of the first resin pipe portion 11. The width E3 of the annular body 90 is more preferably 50 mm or more. The position of the annular body 90 is preferably such that the center line O3 passing through the center of the width E3 of the annular body 90 overlaps with the center position E01 of the width E1 of the arrangement area of ​​the first heating wire 21, or is slightly shifted in the longitudinal direction of the tube. When the center line O3 of the annular body 90 is shifted from the center position E01, it is preferable that the shift from the center position E01 is within 1 / 5 of the width E1 of the arrangement area of ​​the first heating wire 21. In other words, it is preferable that the center line O3 in the width direction of the annular body 90 is positioned within a range of ±(E1) / 5 from the center position E01 of the arrangement area of ​​the first heating wire 21 along the longitudinal direction of the first resin pipe section 11.

[0036] Similarly, an annular body 91 made of a metal band of a predetermined width is provided on the outer periphery of the second resin pipe portion 12. The annular body 91 made of a metal band is provided so as to overlap the arrangement area of ​​the second heating wire 51 and pass through the center position E02 of the width E2 of the heating wire arrangement area. The material constituting the annular body 91 is the same as the material constituting the annular body 90, and the strength of the annular body 91 can also be made the same as that of the annular body 90. In addition, the inner diameter of the annular body 91 can also be made the same as that of the annular body 90.

[0037] The width E4 of the annular body 91 is preferably 30 mm or more in order to suppress an increase in the diameter of the second resin pipe portion 12 during thermal expansion of the second resin pipe portion 12. The width E4 of the annular body 91 is more preferably 50 mm or more. The position of the annular body 91 is preferably such that the center line O4 passing through the center of the width E4 of the annular body 91 overlaps with the center position E02 of the width E2 of the second heating wire 51, or is slightly shifted therefrom. When the center line O4 of the annular body 91 is shifted from the center position E02, it is preferable that the shift from the center position E02 be within 1 / 5 of the width E2 of the arrangement area of ​​the first heating wire 21. In other words, it is preferable that the position of the widthwise center line O4 of the annular body 91 be within a range of ±(E2) / 5 from the center position of the arrangement area of ​​the first heating wire 21 along the length direction of the second resin pipe section 12.

[0038] In the first resin pipe section 11 provided with the ring-shaped body 90, fixing marks (not shown) may be provided on the end face 11d side (receiving port side) from the installation position of the ring-shaped body 90. In the second resin pipe section 12 provided with the ring-shaped body 91, fixing marks (not shown) may be provided on the end face 12d side (receiving port side) from the installation position of the ring-shaped body 91. These fixing marks are support marks of the support parts (needle parts) used when the electric heating wire laying device used for embedding the first electric heating wire in the first resin pipe section 11 holds the resin pipe main body 10. The electric heating wire laying device has, for example, two fixing parts with four needle parts spaced apart from each other. The electric heating wire laying device supports the resin pipe main body 10 by pressing the needle part of one fixing part against the end face 11d of the first resin pipe section 11 and pressing the needle part of the other fixing part against the end face 11d of the second resin pipe section 12. The resin pipe main body 10 is supported between the two fixing parts, and the first electric heating wire 21 can be embedded in the first resin pipe section 11. Also, the second electric heating wire 51 can be embedded in the second resin pipe section 12.

[0039] The number of needles used to support the resin pipe main body 10 may be any number as long as there are more than one, and for example, three or four needles may be provided on each of the end faces 11d and 12d. When providing three needles, they may be provided at 120° intervals around the circumferential direction of the end faces 11d and 12d. When providing four needles, they may be provided at 90° intervals around the circumferential direction of the end faces 11d and 12d. Fixing marks are formed in a number corresponding to the number of needles. Furthermore, the positions where the heating wire installation device supports the first resin pipe section 11 and the second resin pipe section 12 are not limited to the end faces 11d, 12d, but may be the outer or inner peripheral surfaces of the first resin pipe section 11 and the second resin pipe section 12. For example, when supporting at four equally spaced locations around the circumference, fixing marks are formed at 90° intervals around the circumference of the first resin pipe section 11 and the second resin pipe section 12. The shape of the fixing mark is not particularly limited, and the fixing mark is formed according to the shape of the needle part (support part). This fixing mark may be removed by cutting after embedding the heating wire, and may be processed so that no fixing mark remains. Also, the shape of the fixing mark may be arbitrary depending on the shape of the needle part, and the support part may be shaped to form a fixing mark on the recess side.

[0040] (Pipe (plastic pipe) installation method) To carry out a piping construction method in which a first resin pipe 80 and a second resin pipe 81 are fusion-joined using an electric fusion joint 1, the resin pipe body 10 of the electric fusion joint 1 is installed horizontally at a predetermined position on-site. The end of the first resin pipe 80 to be connected is inserted into the first resin pipe section 11, and the second resin pipe 81 to be connected is inserted into the second resin pipe section 12. It is preferable to fully insert the first resin pipe 80 and the second resin pipe 81 into the resin pipe body 10, and then butt the tip of the first resin pipe 80 and the tip of the second resin pipe 81 together in the center of the resin pipe body 10 as shown in FIG. Before the first resin pipe 80, the second resin pipe 81 and the electric fusion joint 1 are installed on site, it is preferable to clean the inner and outer surfaces of these pipes by wiping with acetone or the like.

[0041] It is preferable to previously attach the annular body 90 to the first resin pipe section 11, and the annular body 91 to the second resin pipe section 12. Alternatively, when the electric fusion joint 1 is manufactured in a factory, it is preferable to ship the product with the annular body 90 attached to the first resin pipe section 11 and the annular body 91 attached to the second resin pipe section 12. The electric fusion joint 1 with the annular bodies attached is brought to the site and used for fusion joining as described below. It is preferable that the annular bodies 90, 91 are attached to the electric fusion joint 1 in advance at a factory or the like, but they may be separately delivered to the site and attached to the electric fusion joint 1 by a worker at the site without being attached at the factory. When the annular bodies are made of resin bands as in the second embodiment described later, it is preferable to attach them to the electric fusion joint 1 at the site.

[0042] After the above-mentioned insertion work, the connector 16 at the tip of the connection wire 15A extending from the controller 15 for current supply shown in Fig. 2 is connected to the first terminals 30, 31 and the second terminals 60, 61. Note that in Fig. 2, for the sake of simplicity, only two connectors 16 extending from the controller 15 are shown. In reality, the connectors are connected so that current can be supplied from the controller 15 to the first heating wire 21 via the first terminals 30, 31, and so that current can be supplied from the controller 15 to the second heating wire 51 via the second terminals 60, 61.

[0043] (Power supply to the first heating wire) When the controller 15 applies electricity to the first heating wire 21, the first heating wire 21 can be heated and the resin on the inner circumferential surface of the resin pipe body around the first heating wire 21 and on the outer circumferential surface of the first resin pipe 80 can be heated and melted. The controller 15 may apply electricity to the second heating wire 51 at the same time as the first heating wire 21. After energizing for a predetermined time, the energization from the controller 15 is stopped and the heated and melted portion is cooled, thereby fusing and joining the first resin pipe 80 and the first resin pipe section 11. As heating by energizing the first heating wire 21 progresses, the first indicator 40 protrudes from the outer circumferential surface of the first resin pipe section 11, allowing one to confirm that the fusion and joining has progressed smoothly. When the first resin pipe section 11 is heated by passing electricity through the first heating wire 21, the first resin pipe section 11 tends to expand in diameter due to thermal expansion. However, since the annular body 90 is provided on the outer periphery of the first resin pipe section 11, the expansion of the diameter of the first resin pipe section 11 can be suppressed. As a result, the first resin pipe section 11 can be fusion-joined without increasing the clearance between the inner periphery of the first resin pipe section 11 and the outer periphery of the first resin pipe 80. Therefore, even if the first resin pipe section 11 and the first resin pipe 80 are large-diameter pipes, the first resin pipe 80 and the electric fusion joint 1 can be fusion-joined without causing poor fusion due to the increase in clearance. Here, a large-diameter pipe refers to a pipe with a diameter of 500 mm or more.

[0044] The annular body 90 is arranged so that its widthwise center line O3 is within a range of ±(E1) / 5 from the center position of the arrangement area of ​​the first heating wire 21, so that the expansion of the first resin pipe section 11 is effectively suppressed without bias and an increase in the clearance can be suppressed. If the annular body 90 is provided at a position outside the arrangement area of ​​the first heating wire 21, the thermal expansion of the first resin pipe section 11 will cause a clearance with the first resin pipe 80 to be generated unevenly in the length direction of the pipe. As a result, there is a risk of the clearance expanding in some places, which may cause poor fusion.

[0045] (Power supply to the second heating wire) When current is passed through the second heating wire 51 from the controller 15, the second heating wire 51 can be heated and the resin on the inner circumferential surface of the resin pipe main body around the second heating wire 51 and on the outer circumferential surface of the second resin pipe 81 can be heated and melted. When current is stopped from the controller 15 and the heated and melted portion is cooled, the second resin pipe 81 and the second resin pipe section 12 can be fused together. As heating by passing current through the second heating wire 51 progresses, the second indicator 70 protrudes from the outer circumferential surface of the second resin pipe section 12, making it possible to confirm that fusion joining is progressing smoothly. When the second heating wire 51 is energized to generate heat and heat the second resin pipe section 12, the second resin pipe section 12 tends to expand in diameter due to thermal expansion. However, since the annular body 91 is provided on the outer periphery of the second resin pipe section 12, the expansion of the diameter of the second resin pipe section 12 can be suppressed. As a result, fusion joining can be performed without increasing the clearance between the inner circumferential surface of the second resin pipe section 12 and the outer circumferential surface of the second resin pipe 81. Therefore, even if the second resin pipe section 12 and the second resin pipe 81 are large-diameter pipes, fusion joining can be performed between the second resin pipe 81 and the electric fusion joint 1 without causing poor fusion due to the increase in clearance.

[0046] In addition, since the annular body 91 is arranged so that the widthwise center line O4 of the annular body 91 is within a range of ±(E2) / 5 from the center position of the arrangement area of ​​the second heating wire 51, it is possible to suppress the expansion of the second resin pipe section 12 evenly. If the annular body 91 is provided at a position outside the arrangement area of ​​the second heating wire 51, there is a risk that the thermal expansion of the second resin pipe section 12 will cause the clearance with the second resin pipe 81 to be generated unevenly in the length direction of the pipe, which may cause poor fusion.

[0047] Incidentally, when fusion joining is performed by passing current from the controller 15, current may be passed through the first heating wire 21 and the second heating wire 51 simultaneously to perform fusion joining, or current may be passed through one of them to perform fusion joining, and then current may be passed through the other to perform fusion joining.

[0048] In addition, in the structure of the first embodiment, a single metal band is used as the annular body 90, 91, but an assembly of multiple metal bands may be used as the annular body, and the annular body may be formed by winding a cord such as a metal wire to a width corresponding to the width E3 or width E4 of the metal band. When winding the cable, the winding width of the cable can be regarded as the width E3 or E4 of the metal band. For this reason, assuming a widthwise center line O3 of the winding width of the cable, it is preferable to wind and arrange the cable so that it is within a range of ±(E1) / 5 from the center position of the arrangement area of ​​the first heating wire 21. Also, assuming a widthwise center line O4 of the winding width of the cable, it is preferable to wind and arrange the cable so that it is within a range of ±(E2) / 5 from the center position of the arrangement area of ​​the second heating wire 51. When the annular body is formed by winding a wire, the wire diameter can be 0.2 mm or more and 1.1 mm or less. The Young's modulus of the wire is 65 kN / cm 2 More than 150kN / cm 2 The pitch of the wires may be set to be not less than two times but not more than eight times the wire diameter.

[0049] After the first resin pipe 80 and the second resin pipe 81 are fusion-jointed by the electric fusion joint 1, the annular bodies 90, 91 may be left as they are, or may be removed as necessary. In addition, when installing the metal band rings 90, 91 at the site, grooves or marks can be formed on the outer periphery of the first resin pipe section 11 and the outer periphery of the second resin pipe section 12, making it easy to check the wrapping position of the metal bands. In the first embodiment, a plastic pipe body 10 having the same inner and outer diameters along the length direction was used, but the plastic pipe body 10 may also be a bale-shaped plastic pipe body having a thick wall toward the center of the length direction and a thin wall toward the receiving portion at the end of the length direction. In addition, a correction ring can be provided on-site to correct the flattening of the first resin pipe 80 and the second resin pipe 81, and the deformation of the first resin pipe 80 and the second resin pipe 81 can be corrected before they are inserted into the resin pipe main body 10.

[0050] "Second embodiment" 3 is a side view showing an electrofusion joint according to a second embodiment of the present invention, which differs from the first embodiment in that an annular body 92 made of a resin band is provided instead of the annular body 90 made of a metal band, and an annular body 93 made of a resin band is provided instead of the annular body 91. The width of the annular body 92 is the same as the width E3 of the annular body 90, and the width of the annular body 93 is the same as the width E4 of the annular body 91. As in the case of the metal band, the resin band preferably has a breaking strength of 1 ton or more. When a resin band is used, the resin band is preferably made of polyethylene, polypropylene, nylon, or the like. The other structure is the same as that of the first embodiment.

[0051] For example, even in a structure using resin band ring bodies 92, 93, the ring body 92 is arranged so as to overlap the arrangement area of ​​the first heating wire 21, and the ring body 93 is arranged so as to overlap the arrangement area of ​​the second heating wire 51, which is the same. Also, the width of the annular bodies 92, 93 is preferably 30 mm or more, and more preferably 50 mm or more.

[0052] The position of the annular body 92 is preferably such that the center line O3 of the annular body 92 overlaps with the center position E01 of the width E1 of the arrangement area of ​​the first heating wire 21, or is slightly shifted in the longitudinal direction of the tube. Similarly, when the center line O3 of the annular body 92 is arranged so as to be shifted from the center position E01, it is preferable that the shift from the center position E01 be within 1 / 5 of the width E1 of the arrangement area of ​​the first heating wire 21. The position of the annular body 93 is preferably a position where the center line O4 of the annular body 93 overlaps with the center position E02 of the width E2 of the arrangement area of ​​the second heating wire 51, or a position slightly shifted in the longitudinal direction of the tube. Similarly, when the center line O4 of the annular body 93 is arranged so as to be shifted from the center position E02, it is preferable that the shift width from the center position E02 be within 1 / 5 of the width E2 of the arrangement area of ​​the second heating wire 51.

[0053] (Pipe installation method) By replacing the annular body 90 with annular body 92 made of a resin band and replacing the annular body 91 with annular body 93 made of a resin band, the second embodiment can be constructed in the same manner as the first embodiment, and the same effects can be obtained. Since the resin band is lighter than the metal band, it has the characteristic of being easy to handle. In addition, if a resin band is used, after the electric fusion joint 1 is transported to the site, a worker at the site can wrap the annular body 92 around the outer periphery of the first resin pipe section 11 and the annular body 93 around the outer periphery of the second resin pipe section 12, making it possible to install the joint relatively easily at the site. In the case of a resin band, a resin band whose length can be easily adjusted like a lashing band can be used, and an operator can easily attach the ring-shaped body 92 and the ring-shaped body 93 on-site. Alternatively, the ring-shaped bodies 92 and 93 may be formed by wrapping the resin band around the structure, overlapping the ends of the resin band, and welding the resin bands together on-site. When providing the resin band rings 92, 93, grooves or marks can be formed on the outer periphery of the first resin pipe portion 11 and the outer periphery of the second resin pipe portion 12 to make it easy to confirm the wrapping position of the resin band.

[0054] The lashing band is a resin band with a buckle attached to fix the length of the band. By wrapping this resin band around the outer periphery of the first resin pipe section 11 or the second resin pipe section 12, it can be arranged in a ring shape. By changing the locking position of the band with the buckle, the wrapping position around the first resin pipe section 11 can be adjusted and the wrapping can be performed. In addition, the wrapping position around the second resin pipe section 12 can be adjusted and the wrapping can be performed. When using a lashing band, it is preferable to remove the lashing band after fusing the electric fusion joint 1, the first resin pipe 80, and the second resin pipe 81. When using a lashing band, if the buckle is located below the horizontally placed electric fusion joint 1, the buckle will be sandwiched between the floor or ground at the site and the electric fusion joint 1. In this case, there is a risk that the buckle cannot be adjusted or removed. For this reason, when using a lashing band and removing it after fusion joining, it is preferable to locate the buckle on the side or top side of the electric fusion joint 1.

[0055] In contrast, when using annular bodies 90 and 91 made of metal bands, it is preferable to leave the annular bodies 90, 91 after fusion joining. Figure 4 shows an example of a state in which the annular bodies 90, 91 are left on the outer periphery of the electric fusion joint 1. There is no particular problem with leaving the annular bodies 90, 91 made of metal bands on the outer periphery of the electric fusion joint 1 as shown in Figure 4. Even in the structure using the resin pipe main body 10 having the annular bodies 92, 93 configured as shown in FIG. 2, fusion joining can be performed in the same manner as in the structure of the first embodiment described above. A current is applied from the controller 15 to the first heating wire 21 and the second heating wire 51 to fusion-join the first resin pipe 80 and the second resin pipe 81 to the electric fusion joint 1. In this case, the annular bodies 92 and 93 suppress the expansion of the diameters of the first resin pipe section 11 and the second resin pipe section 12, so that these fusion sections can be fused without generating fusion defects, as in the first embodiment. In addition, the structure of the second embodiment can also provide the same effects as the structure of the first embodiment.

[0056] (Resin pipe insertion jig) 5 shows an example of a resin pipe insertion jig suitable for use when fusion-joining a first resin pipe 80 and a second resin pipe 81, both of which have a large diameter, with an electric fusion joint 1. When fusion-joining a first resin pipe 80 and a second resin pipe 81, both of which have a large diameter, with an electric fusion joint 1, the weight increases, so it may be difficult to manually insert the first resin pipe 80 and the second resin pipe 81 into the electric fusion joint 1 at the site. The resin pipe insertion jig shown in Figure 5 is used when inserting a first resin pipe 80 and a second resin pipe 81 arranged on either side of the electric fusion joint 1 into the first resin pipe portion 11 and the second resin pipe portion 12 of the electric fusion joint 1.

[0057] For example, arc-shaped plate-shaped fixtures 100, 101 are attached to the outer periphery of the first resin tube 80 slightly spaced from the electric fusion joint 1 at positions facing each other with the tube in between. Both ends of the fixtures 100, 101 are fastened together using a lashing band 102 provided along the outer periphery of the first resin pipe 80. By tightening the lashing band 102 and pressing the fixtures 100, 101 against the outer periphery of the first resin pipe 80, the fixtures 100, 101 can be pressed and fixed against the outer periphery of the first resin pipe 80. A band with an adjustable length is used as the lashing band 102, and the fixing position of the lashing band by the buckle can be adjusted. This allows the inner diameter of the annular portion of the lashing band 102 to be adjusted, and the lashing band 102 can be fastened and the fixtures 100, 101 can be pressed against the outer periphery of the first resin pipe 80.

[0058] Similarly, arc-shaped fixtures 103 and 104 are attached to the outer periphery of the second resin tube 81 slightly spaced from the electric fusion joint 1 at positions facing each other with the tube in between in the radial direction. Both ends of the fixtures 103, 104 are fastened together using a lashing band 105 provided along the outer periphery of the second resin pipe 81. The fixtures 103, 104 can be fixed to the outer periphery of the second resin pipe 81 by tightening the lashing band 105 and pressing the fixtures 104, 105 against the outer periphery of the second resin pipe 81. A band whose length is adjustable is used as the lashing band 105, and the fixing position of the lashing band by the buckle can be adjusted. This allows the length of the lashing band 105 to be adjusted, and the lashing band 105 can be fastened and the fixtures 103, 104 can be pressed against the outer periphery of the second resin pipe 81.

[0059] A chain member 107 of a chain block (lever block: registered product name of Kito Corporation) 106 is installed between the opposing ends of a fixture 100 attached to the first resin pipe 80 and a fixture 104 attached to the second resin pipe 81. The chain block 106 has a feature that the length of the chain block 106 can be adjusted by repeatedly rotating a lever member 108. As shown in FIG. 5, the chain block 106 is arranged along the length direction of the first resin pipe 80 and the second resin pipe 81. When arranging the chain members 107 of the chain block 106, as one example, four chain members 107 can be provided at 90° intervals in the circumferential direction of the first resin pipe 80 and the second resin pipe 81. Since the ends of the fixing devices 103, 104 are located at the positions shown in FIG. 5 and also at the rear side of the paper in FIG. 5, in addition to the pair of chain members 107 and chain block 106 shown in FIG. 5, a pair of chain members 107 and chain block 106 is also provided at the rear side of the paper in FIG. 5. For this reason, four chain members 107 and chain blocks 106 are provided at 90° intervals in the circumferential direction of the first resin pipe 80 and the second resin pipe 81.

[0060] FIG. 5 shows a state in which a first resin pipe 80 and a second resin pipe 81 are arranged on either side of the electric fusion joint 1 in a coaxial position with the electric fusion joint 1, fasteners 103 and 104 are fixed to the outer periphery of the second resin pipe 81, and both ends of the opposing fasteners 103 and 104 are connected by a chain member 107 of a chain block 106.

[0061] From this state, the lever members 108, 108 are repeatedly rotated back and forth to shorten the chain members 107, 107, whereby the first resin pipe 80 and the second resin pipe 81 can be inserted into the inside of the electric fusion joint 1. When the first resin pipe 80 and the second resin pipe 81 have been inserted deep inside the electric fusion joint 1 and the tip of the first resin pipe 80 and the tip of the second resin pipe 81 are butted together, the insertion operation is completed. At this point, the fastening between the lashing band 105 and the chain member 107 is loosened, and the fixing devices 103, 104, the chain block 106, and the chain member 107 are removed. Thereafter, as described above with reference to Figure 2, the connector 16 of the controller 15 is connected to the first terminal 30 (31) or the second terminal 60 (61), and electrical fusion is performed by passing electricity through the connector 16, thereby fusion-joining the first resin tube 80 and the second resin tube 81.

[0062] "Third embodiment" FIG. 6 is a side view showing an electric fusion joint according to the third embodiment of the present invention. In the resin pipe main body 10 of the first embodiment, the first resin pipe section 11 and the second resin pipe section 12 have the same diameter. In contrast, in the electric fusion joint 110 of the third embodiment, the second resin pipe section 17 is formed to have smaller inner and outer diameters than the first resin pipe section 11. The second resin pipe section 17 has a smaller diameter than the first resin pipe section 11, but the other structure is the same as the second resin pipe section 12 described above.

[0063] The second resin pipe section 17 has a second heating wire 52 on its inner periphery, a second wire withdrawal hole 65 (66) on its outer periphery, and a second terminal 67 (68) connected to the second heating wire 52. It has a second recess 72 and a second indicator 73 at a position adjacent to the second terminal 67. A ring-shaped body 95 is provided on the outer periphery of the second resin pipe section 17 at a position adjacent to the second indicator 73. The ring-shaped body 95 is provided in the same manner as the ring-shaped body 91 of the first embodiment, at a position that does not interfere with the second terminal 67 (68) and the second indicator 73. Into the second resin pipe portion 17, a second resin pipe 82 having an inner diameter and an outer diameter smaller than those of the second resin pipe 81 used in the previous embodiment and an outer diameter that can be inserted into the second resin pipe portion 17 is inserted.

[0064] A second fusion portion 53 is provided on the inner surface 17a of the second resin pipe portion 17, and in the second fusion portion 53, a second heating wire 52 is inserted into a second notched groove formed in a spiral shape on the inner surface 17a of the second resin pipe portion 17. The other structure is similar to that of the first embodiment.

[0065] According to the structure of the second embodiment, as in the previous embodiment, when the controller 15 applies electricity to the second heating wire 52, the second heating wire 52 can be heated and the resin on the inner circumferential surface of the resin pipe main body around the second heating wire 52 and on the outer circumferential surface of the second resin pipe 82 can be heated and melted. When the application of electricity from the controller 15 is stopped and the heated and melted portion is cooled, the second resin pipe 82 and the second resin pipe section 17 can be fused together. As the heating by the application of electricity to the second heating wire 52 progresses, the second indicator 73 protrudes from the outer circumferential surface of the second resin pipe section 17, so that it can be confirmed that the fusion joining has progressed smoothly.

[0066] As in the structure shown in FIG. 6, by using an electric fusion joint 110, a second resin pipe 82 having a different diameter can be fusion-joined to a first resin pipe 80. When electricity is passed through the heating wire 52 of the second resin pipe section 17 to heat the heating wire 52 and fuse the inner periphery of the second resin pipe section 17 and the outer periphery of the second resin pipe 82, the second resin pipe section 17 attempts to expand in diameter due to thermal expansion, but the annular body 95 suppresses the expansion of the diameter of the second resin pipe section 17. Therefore, the second resin pipe 82 can be fusion-joined to the second resin pipe section 17 via the electric fusion joint 1 without increasing the clearance between the second resin pipe section 17 and the second resin pipe section 17. [Explanation of symbols]

[0067] 1... Electric fusion joint, 10...Resin pipe body, 11...first resin pipe section, 12, 17...second resin pipe section, 20...first fusion part, 21...first heating wire, 30, 31…Terminal 1, 40…First indicator, 50, 53...second fusion part, 51, 52...second heating wire, 60, 61, 67, 68…Terminal 2, 70, 73…Second indicator, 80...first resin pipe, 82...Second resin pipe, 90, 91, 95...Annular body (metal band), 92, 93...Annular body (resin band), E: heating wire arrangement area, E1: Area where the first heating wire is arranged, E2: Area where the second heating wire is arranged,

Claims

1. An electric fusion joint having an electric heating wire disposed on an inner periphery of a thermoplastic resin pipe body into which a resin pipe to be connected is inserted, the portion where the electric heating wire is provided being a fusion portion, The resin pipe body is provided with an annular body in contact with the outer peripheral surface of the resin pipe body at a position that overlaps with the electric heating wire arrangement area in which the electric heating wire is provided along the length direction of the resin pipe body, Electric fusion joint.

2. The annular body is any one of a metal band, a resin band, and a lashing band. The electric fusion joint according to claim 1.

3. When the width of the arrangement area of ​​the electric heating wire along the length direction of the resin pipe body is E, the position where the width direction center of the annular body along the length direction of the resin pipe body is arranged is within a region of ±E / 5 from the center position of the arrangement area of ​​the electric heating wire along the length direction of the resin pipe body. The electric fusion joint according to claim 1 or 2.

4. The position width at which the annular body is installed along the longitudinal direction of the resin pipe body is 30 mm or more and the value of E or less. The electric fusion joint according to claim 3.

5. A terminal connected to the heating wire and an indicator for confirming electrical fusion are provided on the outer periphery of the resin pipe body, and the annular body is disposed at a position where it does not interfere with the terminal and the indicator. The electric fusion joint according to claim 1 or 2.

6. A piping construction method for fusion-connecting a plastic pipe to an electric fusion joint having an electric heating wire disposed on an inner periphery of a thermoplastic plastic pipe body into which a plastic pipe to be connected is inserted, the electric heating wire being a fusion joint at a portion where the electric heating wire is provided, An electric fusion joint is carried to the site, the electric fusion joint having an annular body that contacts the outer peripheral surface of the resin pipe body at a position that overlaps with an electric heating wire arrangement area where the electric heating wire is provided along the length direction of the resin pipe body, After inserting the resin pipe into the resin pipe main body, the resin pipe main body and the resin pipe are fused together by passing an electric current through the heating wire. Piping installation methods.

7. A piping construction method for fusion-connecting a plastic pipe to an electric fusion joint having an electric heating wire disposed on an inner periphery of a thermoplastic plastic pipe body into which a plastic pipe to be connected is inserted, the electric heating wire being a fusion joint at a portion where the electric heating wire is provided, After the electric fusion joint is delivered to the site, a ring-shaped body is provided in contact with the outer peripheral surface of the resin pipe body at a position that overlaps with an electric heating wire arrangement area in which the electric heating wire is provided along the length direction of the resin pipe body, on the outer periphery of the resin pipe body; After inserting the resin pipe into the resin pipe main body, the resin pipe main body and the resin pipe are fused together by passing an electric current through the heating wire. Piping installation methods.

8. After the resin pipe body and the resin pipe are welded together by the current passing, the annular body is removed from the resin pipe body. The piping installation method according to claim 7.

9. When the width of the arrangement region of the electric heating wire along the length direction of the plastic pipe body is E, a region within ±E / 5 from the center position of the arrangement region of the electric heating wire along the length direction of the plastic pipe body is selected as a position where the width direction center of the annular body along the length direction of the plastic pipe body is to be arranged. A piping installation method according to claim 6 or 7.

10. The width of the annular body along the longitudinal direction of the resin pipe body is set to 30 mm or more and the value of E or less. The piping installation method according to claim 9.

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