Connection structure and connection method for pipe joint and pipe

Abstract

To enable an end part of a pipe to be reliably and firmly joined and connected to a connection port of a joint having an uneven outer peripheral surface.SOLUTION: In a connection structure between a pipe joint and a pipe, an inner peripheral surface of the pipe is pressure-fitted and connected to an outer peripheral surface of a connection port protruding from the pipe joint, and a tightening ring is pressure-fitted to the outer peripheral surface of the pipe from a root part to a tip part of the connection port of the pipe joint inserted into the pipe, and a ratio Tp / Tw of a thickness Tw of the tightening ring to a thickness Tp of the pipe is 0.55 to 1.00.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a connection structure and a connection method between a pipe joint and a pipe.

Background Art

[0002] Typical cross-linked polyethylene pipes as resin pipes are made of chemically stable materials, lightweight, flexible, easy to transport, and excellent in workability of piping work at construction sites. Therefore, they are widely used as conduits for transporting liquids and gases in facilities for heating, air conditioning, and water supply and drainage.

[0003] When connecting a resin pipe to a pipe joint of another conduit, the end opening of the pipe is reversibly expanded at atmospheric temperature to be larger than the outer diameter of the connection port of the conduit or pipe joint to be connected, and in that state, the end of the expanded pipe is fitted into the connection port. Then, the expanded end can be firmly sealed and joined to the outer peripheral surface of the connection port by the automatic return deformation at atmospheric temperature.

[0004] Also, it is described in Patent Document 1 that a synthetic resin tightening ring is previously attached to the outer peripheral surface of the pipe, and in that state, the end opening of the pipe is expanded and fitted into the connection port of the joint. According to the structure of this Patent Document 1, variations in tightening by construction workers are eliminated, and the tightening ring does not come off.

[0005] The connection method of Patent Document 1 is a connection method between a pipe joint and a cross-linked polyethylene pipe. It is a cross-linked polyethylene tubular tightening ring having a wall thickness (Tw in FIG. 5) having a relationship of 1.2 ≦ Tp / Tw ≦ 9.0 with respect to a pipe having a wall thickness (Tp in FIG. 5), and the length in the axial direction thereof has a length at least extending from the root portion to the tip portion of the connection port of the pipe joint. A step of expanding the end opening of the tightening ring and press-fitting it onto the outer peripheral surface of the pipe, and a step of expanding the end opening of the pipe with the tightening ring attached to the outer peripheral surface and press-fitting it onto the outer peripheral surface of the connection port of the pipe joint.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the structure of Patent Document 1, although Tp / Tw is considered, there is a problem that the pipe needs to be thickened deviating from the pipe diameter according to the JIS standard, resulting in a high overall system cost.

[0008] In view of such problems of Patent Document 1, the present invention aims to securely and firmly connect and join the end of a pipe to the connection port of a joint with unevenness on its outer peripheral surface, and to enable the pipe diameter to be configured within the inner and outer diameters of the resin pipe range specified by the normal JIS (for example, the inner and outer diameters within the range specified by JIS K 6769 for a cross-linked polyethylene pipe).

Means for Solving the Problems

[0009] The gist of the present invention is as follows.

[0010] [1] In a connection structure between a pipe joint and a pipe, the pipe is connected by press-fitting the inner peripheral surface thereof onto the outer peripheral surface of the connection port protruding from the pipe joint, and a tightening ring is press-fitted and fixed to the connection port in a region of the outer peripheral surface of the pipe extending from the root portion to the tip portion of the connection port of the pipe joint inserted into the pipe, and a connection structure between a pipe joint and a pipe, characterized in that the ratio Tp / Tw of the thickness Tw of the tightening ring to the thickness Tp of the pipe is 0.55 to 1.00.

[0011] [2] The pipe joint and the pipe connection structure according to [1], wherein a plurality of inclined step portions whose diameters expand from the tip side to the root side are formed on the outer peripheral surface of the connection port.

[0012] [3] The inner diameter (d2) of the pipe is smaller than the maximum outer diameter (φco) of the connection port of the pipe joint, and the inner diameter of the end opening of the pipe is expanded at a rate of 3 to 10% and the pipe is connected to the connection port. The pipe joint and the pipe connection structure according to [1].

[0013] [4] The constituent materials of the pipe and the tightening ring are such that the tensile stress at 10% elongation based on their stress-strain curves is 10 MPa or more, and the elongation (strain) at break is 300% or more. The pipe joint and the pipe connection structure according to [1].

[0014] [5] A method for connecting a pipe joint and a pipe for constructing the pipe joint and pipe connection structure according to any one of [1] to [4], a step of expanding the end opening of a cross-linked polyethylene tightening ring and press-fitting it onto the outer peripheral surface of the pipe; a step of expanding the end opening of the pipe with the tightening ring mounted on its outer peripheral surface and press-fitting it onto the outer peripheral surface of the connection port of the pipe joint and a method for connecting a pipe joint and a pipe having the above steps.

[0015] Note that when the pipe is press-fitted into the pipe joint, it means that the pipe is tightly fitted into the pipe joint. When the tightening ring is press-fitted into the pipe, it means that the tightening ring is tightly fitted into the pipe.

Advantages of the Invention

[0016] The present invention adopts a connection mode in which a tightening ring is mounted on the outer peripheral surface of a pipe connected to the connection port of a joint. By appropriately setting the ratio D2 / d1 of the inner diameter D2 of the tightening ring to the outer diameter d1 of the pipe, the end of the pipe is surely and firmly connected to the connection port of the joint by a smooth connection operation.

[0017] That is, in the present invention, the ratio Tp / Tw of the thickness Tw of the clamping ring to the thickness Tp of the pipe is in the range of 0.55 to 1.00.

[0018] According to this, since the clamping ring is press-fitted and mounted over the region from the root portion to the tip portion of the connection port of the pipe joint inserted into the pipe on the outer peripheral surface of the pipe, the pipe can be tightened and fixed to the connection port while maintaining the adhesion strength between the inner peripheral surface of the pipe and the connection port evenly.

[0019] Also, the operation of mounting the pipe on the clamping ring can be easily performed.

[0020] Note that if Tp / Tw is less than 0.55, the clamping ring cannot be expanded in the elastic deformation range and mounted on the pipe. If Tp / Tw is greater than 1.00, the cost will increase because a special pipe deviating from the JIS standard is used.

[0021] The structure of the present invention is suitable for a mode of connecting a pipe to a pipe joint in which a plurality of inclined stepped portions that expand in diameter from the tip side to the root side are formed on the outer peripheral surface of the connection port. However, it can also be applied to the connection between a pipe joint in a form other than such a pipe joint and a pipe.

[0022] The pipe joint preferably used in the present invention is in a form in which the connection port to which the pipe is connected is formed such that the outer diameter tapers from the root side toward the tip side. The present invention can be applied to a connection structure between a pipe joint and a pipe in which a pipe having an inner diameter smaller than the maximum outer diameter (φco) of the connection port of the pipe joint is press-fitted into the connection port of the pipe joint while expanding the inner diameter of the end opening.

[0023] Also, in one aspect of the present invention, the inner diameter (d2) of the pipe is smaller than the maximum outer diameter (φco) of the connection port of the pipe joint, and the inner diameter of the end opening of the pipe is expanded at an expansion rate of 3 to 15% and the pipe is connected to the pipe joint connection port.

[0024] If the diameter expansion rate is 3 to 15%, the inner peripheral surface of the pipe can be pressed against the outer peripheral surface of the connection port with sufficient strength by the automatic return deformation after connecting to the connection port of the pipe joint, and high sealing performance can be exhibited.

[0025] In one aspect of the present invention, the molding materials of the pipe and the clamping ring have a tensile stress of 10 MPa or more at 15% elongation based on their stress-strain curves, and a physical property with an elongation (strain) at break of 300% or more.

[0026] That is, FIG. 6 shows the stress-strain curve (SSC) of the crosslinked polyethylene constituting a general crosslinked polyethylene pipe for water supply. Point A in the figure is the elastic limit point, and it is a point indicating the tensile stress at approximately 10 to 15% elongation.

[0027] The stress at point A corresponds to the value of the tensile stress generated when the diameter expansion rate of the pipe or the clamping ring is approximately 15%. Therefore, the higher the stress value at point A, the higher the clamping force of the joint.

[0028] From this perspective, it is preferable that the crosslinked polyethylene constituting the pipe and the clamping ring of the present invention has a tensile stress value of 10 MPa or more at 15% elongation based on the stress-strain curve, more preferably 15 MPa or more, and even more preferably 20 MPa or more.

[0029] Point B in FIG. 1 is the breaking point, and the elongation at this time is the elongation at break. The elongation at break is preferably 300% or more, more preferably 350% or more, and even more preferably 400% or more.

[0030] The method for connecting the pipe joint and the pipe of the present invention is a method for connecting the pipe joint and the pipe for constituting the connection structure of the pipe joint and the pipe of the present invention, and includes a step of expanding the end opening of the crosslinked polyethylene clamping ring and press-fitting it onto the outer peripheral surface of the pipe, and a step of expanding the end opening of the pipe with the clamping ring mounted on its outer peripheral surface and press-fitting it onto the outer peripheral surface of the connection port of the pipe joint.

[0031] In this case, if necessary, the end opening of the pipe with the clamping ring mounted on the outer peripheral surface may be heated and connected to the connection port of the joint.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0033] Hereinafter, an embodiment of the connection structure between the pipe joint and the pipe of the present invention will be described with reference to the drawings. Note that the present invention is not limited to this embodiment.

[0034] The illustrated embodiment is a mode of connecting a synthetic resin pipe to a synthetic resin joint that is a pipe joint. In the figure, reference numeral 1 is the pipe, 2 is the clamping ring, 3 is the pipe joint, and 31 is the connection port of the pipe joint 3.

[0035] In this embodiment, both the pipe 1 and the clamping ring 2 are crosslinked polyethylene pipes, and this crosslinked polyethylene has physical properties defined by the stress-strain curve shown in FIG. 6.

[0036] Pipe 1 has an inner diameter (d2) smaller than the maximum outer diameter (the diameter φco of the root part) of the connection port 31 of the pipe joint 3, and the inner diameter of the end opening of the pipe 1 is expanded at an expansion rate of 3 to 15% and then connected to the connection port 31.

[0037] In addition, a clamping ring 2 with a ratio Tp / Tw of the thickness (Tw) of the clamping ring 2 to the thickness (Tp) of the pipe 1 being 0.55 to 1.00 is used. Also, the clamping ring 2 has an axial length that is at least as long as the length L from the root part to the tip part of the connection port 31 of the pipe joint 3. The ratio L / d2 of the length L of this connection port 31 to the inner diameter d2 of the pipe 1 is preferably about 0.40 to 0.60.

[0038] The connection of the pipe 1 to the pipe joint 3 is carried out by a work procedure in which first, the clamping ring 2 is attached to the outer peripheral surface of the pipe 1, and then the pipe 1 with the clamping ring 2 attached is connected to the connection port 31 of the pipe joint 3.

[0039] That is, first, as shown in FIG. 2, the tip part 4A of the diameter-expanding tool 4 is pushed into one end side of the clamping ring 2, etc., to expand the inner diameter of the one end side of the clamping ring 2.

[0040] The diameter-expanding tool 4 has a base part 4B and a tip part 4A protruding from the base part 4B. The tip part 4A has a plurality (4 in this embodiment) of movable pieces 4a. The tip part 4A has a tapered cylinder shape that reduces in diameter from the middle to the tip.

[0041] A slit-like gap 4b extending in the longitudinal direction is provided in the tapered cylinder-shaped tip part 4A. The four movable pieces 4a are arranged in the circumferential direction with the gap 4b between them, thereby forming the tip part 4A.

[0042] A mechanism for advancing and retreating each movable piece 4a in the radial direction of the tip part 4A is incorporated in the base part 4B, whereby the tip part 4A can expand and contract in the radial direction.

[0043] After inserting the tip portion 4A into the clamping ring 2, the clamping ring 2 can be expanded by expanding the tip portion 4A. As this expanding tool 4, a commercially available product can be used.

[0044] The tip portion 4A is pushed into the clamping ring 2 from one end side of the clamping ring 2 to near the middle in the length direction of the clamping ring 2 to expand the inner diameter of the clamping ring 2, and then the tip portion 4A is removed from the clamping ring 2. The one end side of the clamping ring 2 maintains an expanded state for a while. Therefore, the expanded one end side is covered and pushed onto the outer peripheral surface of one end portion of the pipe 1 as shown in Fig. 3(a), and the clamping ring 2 is press-fitted and mounted (mounted so as to be tightly fitted) on the outer peripheral surface of the one end portion of the pipe 1 as shown in Fig. 3(b).

[0045] The operation of mounting the clamping ring 2 on the pipe 1 can be performed by covering the expanded one end portion side of the clamping ring 2 on the outer peripheral surface of one end portion of the pipe 1 and hitting and pushing the other end portion of the clamping ring 2 with a rubber hammer.

[0046] As another method, the entire length direction of the clamping ring 2 may be expanded by the expanding tool 4, and after removing the expanding tool 4, it may be mounted on the outer peripheral surface of one end portion of the pipe 1.

[0047] The clamping ring 2 gradually restores to its original shape thereafter and comes into close contact with the outer peripheral surface of the pipe 1 to be in a tightly press-fitted state.

[0048] In addition, when the one end side of the clamping ring 2 is expanded considerably, there may be a gap between the one end side of the clamping ring 2 and the pipe 1 immediately after mounting the clamping ring 2 on the pipe 1. However, as the clamping ring 2 contracts over time, the entire inner peripheral surface of the clamping ring 2 comes into close contact with the outer peripheral surface of the pipe 1, resulting in a tightly press-fitted state (Fig. 3(b)) in which the pipe 1 is tightly clamped.

[0049] Next, the pipe 1 with the clamping ring 2 mounted on the outer peripheral surface of one end is press-fitted and mounted on the outer peripheral surface of the connection port 31 of the pipe joint 3 as shown in Fig. 4.

[0050] For example, with the connection port 31 of the pipe joint 3 inserted into the end opening of the pipe 1 with the clamping ring 2 mounted, the pipe joint 3 is tapped with a rubber hammer from the rear end 32 side to push the entire connection port 31 into the pipe 1, or an insertion tool such as a smoother is used to push the entire connection port 31 toward the pipe 1 side, so that the connection port 31 can be press-fitted and mounted on the end of the pipe 1. At this time, if necessary, by heating the vicinity of one end of the pipe 1 and the clamping ring 2, the operation of pushing the connection port 31 of the pipe joint 3 into the pipe 1 can be performed smoothly.

[0051] When it is difficult to press-fit and mount the pipe joint 3 onto the connection port 31 of the pipe joint 3, the diameter of one end of the pipe 1 with the clamping ring 2 mounted may be expanded, and in that case, the diameter expansion tool 4 can be used.

[0052] As described above, the ratio Tp / Tw of the thickness Tw of the clamping ring 2 to the thickness Tp of the pipe 1 is 0.55 to 1.00, preferably 0.55 to 0.80. If Tp / Tw is less than 0.55, the clamping ring 2 cannot be expanded within the elastic limit range and press-fitted onto the pipe 1. That is, when one end side of the clamping ring 2 is expanded, plastic deformation occurs and strain remains, resulting in loose clamping of the clamping ring 2 to the pipe 1. If Tp / Tw is greater than 1.00, the cost increases because a special pipe that deviates from the JIS standard is used.

Example

[0053] 〔Example 1〕 A pipe 1 made of cross-linked polyethylene with an outer diameter d1 of 13.0 mm and an inner diameter d2 of 9.8 mm, and a clamping ring made of cross-linked polyethylene with an outer diameter D1 of 13.0 mm, an inner diameter D2 of 9.8 mm, and an axial length of 17.5 mm were prepared. The stress-strain curve of this cross-linked polyethylene is as shown in Fig. 6.

[0054] A clamping ring 2 was press-fitted onto the outer periphery of the end of this pipe 1 as shown in FIGS. 2 to 3. At this time, the diameter expansion rate of one end of the clamping ring 2 was 11.0%. For a synthetic resin pipe fitting 3 with an outer diameter of 9.5 mm at the tip of the connection port 31 and an outer diameter φco of 11.0 mm at the base of the connection port 31, the pipe 1 with the clamping ring 2 was connected to form the state shown in FIG. 5. The length L of the connection port 31 of the pipe fitting 3 is 20.5 mm.

[0055] The above connection work was carried out as follows.

[0056] First, the end opening of the clamping ring 2 was expanded using an expanding tool 4. Then, the tip of the pipe 1 was inserted into one end of the clamping ring 2, and the other end of the clamping ring 2 was tapped with a rubber hammer and pushed onto the outer peripheral surface of the pipe 1 until the entire clamping ring 2 overlapped with the outer peripheral surface of the pipe 1.

[0057] Next, after expanding the tip of the pipe 1 with the clamping ring 2 using the expanding tool 4, the pipe fitting 3 was tapped with a rubber hammer against the expanded portion of the pipe 1 and the clamping ring 2, and the entire connection port 31 was pushed onto the pipe 1 and fixed.

[0058] In this Example 1, Tp / Tw = 1.6 / 1.6 = 1.00. Table 1 shows the results of evaluating the pipe clamping force and the ease of inserting the pipe in this Example 1.

[0059] Note that the clamping force and the ease of inserting the pipe were evaluated according to the following criteria.

[0060] [Clamping force] The rear end 32 of the pipe fitting 3 was closed with a socket nut. A water pressure (2.5 Ma) was applied to the pipe 1 connected to this pipe fitting 3. If the pipe 1 was broken without coming out from the connection port 31 of the pipe fitting, it was marked as ○, and if the pipe 1 came out from the connection port 31 of the pipe fitting, it was marked as ×. [Ease of inserting the pipe] Regarding the ease of fitting when fitting the pipe joint 3 onto the pipe 1 with the clamping ring 2 attached by hitting it with a hammer, those that could be fitted up to the base of the connection port 31 were marked as ○, and those that could not reach the base were marked as ×.

[0061] 〔Example 2〕 The connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1, except that a clamping ring with an outer diameter d1 of 17.0 mm and an inner diameter d2 of 12.9 mm was used. The results are shown in Table 1.

[0062] 〔Example 3〕 The connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1, except that a clamping ring with an outer diameter D1 of 17.0 mm and an inner diameter D2 of 11.2 mm was used. The results are shown in Table 1.

[0063] 〔Example 4〕 The connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1, except that a pipe with an outer diameter d1 of 17.0 mm and an inner diameter d2 of 12.9 mm was used, and a clamping ring with an outer diameter D1 of 21.5 mm and an inner diameter D2 of 16.2 mm was used. The results are shown in Table 1.

[0064] 〔Example 5〕 The connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1, except that a pipe with an outer diameter d1 of 21.5 mm and an inner diameter d2 of 16.2 mm was used, and a clamping ring with an outer diameter D1 of 27.0 mm and an inner diameter D2 of 20.5 mm was used. The results are shown in Table 1.

[0065] 〔Example 6〕 The connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1, except that a pipe with an outer diameter d1 of 27.0 mm and an inner diameter d2 of 20.5 mm was used, and a clamping ring with an outer diameter D1 of 34.0 mm and an inner diameter D2 of 26.0 mm was used. The results are shown in Table 1.

[0066] 〔Comparative Example 1〕 As the pipe, one with an outer diameter d1 of 24.2 mm and an inner diameter d2 of 16.2 mm was used. As the clamping ring, one with an outer diameter D1 of 27.0 mm and an inner diameter D2 of 20.5 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

[0067] 〔Comparative Example 2〕 As the pipe, one with an outer diameter d1 of 24.2 mm and an inner diameter d2 of 16.2 mm was used. As the clamping ring, one with an outer diameter D1 of 21.5 mm and an inner diameter D2 of 16.2 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

[0068] 〔Comparative Example 3〕 As the pipe, one with an outer diameter d1 of 24.2 mm and an inner diameter d2 of 16.2 mm was used. As the clamping ring, one with an outer diameter D1 of 14.6 mm and an inner diameter D2 of 9.8 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

[0069] 〔Comparative Example 4〕 As the pipe, one with an outer diameter d1 of 24.2 mm and an inner diameter d2 of 16.2 mm was used. As the clamping ring, one with an outer diameter D1 of 17.0 mm and an inner diameter D2 of 12.6 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

[0070] 〔Comparative Example 5〕 As the pipe, one with an outer diameter d1 of 24.2 mm and an inner diameter d2 of 16.2 mm was used. As the clamping ring, one with an outer diameter D1 of 13.0 mm and an inner diameter D2 of 9.8 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were performed in the same manner as in Example 1. The results are shown in Table 1.

[0071] 〔Comparative Example 6〕 As the pipe, one with an outer diameter d1 of 14.6 mm and an inner diameter d2 of 9.8 mm was used. As the clamping ring, one with an outer diameter D1 of 17.0 mm and an inner diameter D2 of 12.8 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0072] 〔Comparative Example 7〕 As the pipe, one with an outer diameter d1 of 13.0 mm and an inner diameter d2 of 9.8 mm was used. As the clamping ring, one with an outer diameter D1 of 17.0 mm and an inner diameter D2 of 13.0 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0073] 〔Comparative Example 8〕 As the pipe, one with an outer diameter d1 of 13.0 mm and an inner diameter d2 of 9.8 mm was used. As the clamping ring, one with an outer diameter D1 of 17.0 mm and an inner diameter D2 of 9.8 mm was used. Except for this, the connection of the pipe to the pipe joint and the evaluation were carried out in the same manner as in Example 1. The results are shown in Table 1.

[0074]

Table 1

[0075] [Discussion] In Examples 1 to 6 where Tp / Tw is in the range of 0.55 to 1.00, in each case, the pipe 1 was fixed to the pipe joint 3 with sufficient clamping force, and the pipe 1 could be easily fitted to the root of the connection port 31 of the pipe joint 3. Furthermore, pipes conforming to JIS standards could be used, and the cost could be reduced.

[0076] On the other hand, in Comparative Examples 1 to 6, Tp / Tw is greater than 1.00. Compared with the examples, the cost increased because special pipes deviating from the JIS standards were used.

[0077] Also, in Comparative Example 7, the pipe could not be fitted in.

[0078] Note that the illustrated pipe 1, clamping ring 2, and pipe joint 3 show an example form of the present invention. The present invention is not limited to the illustrated form and can be configured in other appropriate forms.

Explanation of Signs

[0079] 1 Pipe 2 Clamping Ring 3 Pipe Joint 4 Tool for Diameter Expansion 31 Connection Port 32 Rear End of Pipe Joint

Claims

1. In a connection structure between a pipe joint and a pipe, the pipe is press-fitted and connected to the outer peripheral surface of a connection port protruding from the pipe joint on its inner peripheral surface, and a tightening ring is press-fitted and fixed to the connection port in a region of a portion of its outer peripheral surface extending from the root portion to the tip portion of the connection port of the pipe joint inserted into the pipe. A connection structure between a pipe joint and a pipe, characterized in that the ratio Tp / Tw of the thickness Tw of the tightening ring to the thickness Tp of the pipe is 0.55 to 1.

00.

2. The connection structure between a pipe joint and a pipe according to claim 1, characterized in that the pipe joint is formed with a plurality of inclined stepped portions whose outer peripheral surface expands in diameter from the tip side to the root side at the connection port.

3. The inner diameter (d2) of the pipe is smaller than the maximum outer diameter (φco) of the connection port of the pipe joint. The connection structure between a pipe joint and a pipe according to claim 1, characterized in that the pipe is connected to the connection port after the inner diameter of the end opening of the pipe is expanded at a rate of 3 to 15%.

4. The connection structure between a pipe joint and a pipe according to claim 1, characterized in that the constituent materials of the pipe and the tightening ring have a tensile stress of 10 MPa or more at 10% elongation based on their stress-strain curves and an elongation (strain) at break of 300% or more.

5. A method for connecting a pipe joint and a pipe for constructing the connection structure between a pipe joint and a pipe according to any one of claims 1 to 4, comprising a step of expanding the end opening of a cross-linked polyethylene tightening ring and press-fitting and mounting it on the outer peripheral surface of the pipe, and a step of expanding the end opening of the pipe with the tightening ring mounted on its outer peripheral surface and press-fitting and mounting it on the outer peripheral surface of the connection port of the pipe joint. A method for connecting a pipe joint and a pipe.

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