Pipe joint and method for constructing pipe

Abstract

To provide a pipe joint and a construction method of a pipe capable of being miniaturized.SOLUTION: The main pipe portion 12 and the branch pipe portion 13 have a pipe outer diameter of 60mm or more, and at least one of a branch port portion 71 of the branch pipe portion 13 on a side opposite to the main pipe portion 12 and a main pipe port portion 3151 of the main pipe portion 12 on a side opposite to the branch pipe portion 13 is an insertion port, in the branch pipe section (13), the outer diameter of a root section (72) on the main pipe section (12) side is the same as the outer diameter of a branch opening section (71) on the side opposite to the main pipe section (12), and a reinforcing section (15) bulging in the in-pipe direction is provided at the intersection (14) where the main pipe section (12) and the branch pipe section (13) intersect.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pipe joint and a piping installation method. [Background technology]

[0002] Some pipe joints have a main pipe section with insertion ports at both ends and at least one branch pipe section branching off from the middle of the main pipe section. When such pipe joints are made of synthetic resin, a reinforcing section that bulges outward from the pipe is provided at the intersection where the main pipe section and the branch pipe section intersect, in order to ensure strength (see, for example, Patent Document 1 (Figure 8)). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-51840 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, there is a demand for smaller pipe joints.

[0005] In view of the above circumstances, an object of the present invention is to provide a pipe joint and a piping installation method that enable miniaturization. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention proposes the following aspects. <1> A pipe fitting according to one aspect of the present invention comprises: A pipe joint made of synthetic resin, having at least one branch pipe section branching off from a main pipe section, for pumping a fluid, The main pipe section and the branch pipe section have an outer diameter of 60 mm or more, At least one of a branch opening portion of the branch pipe portion opposite to the main pipe portion and a main pipe opening portion of the main pipe portion opposite to the branch pipe portion is an insertion port, The branch pipe portion is The outer diameter of the base portion on the main pipe side and the outer diameter of the branch opening portion are the same diameter, A reinforcing portion that bulges outward inward from the main pipe portion and the branch pipe portion is provided at the intersection where the main pipe portion and the branch pipe portion intersect.

[0007] <1> According to the pipe fittings, Because the outer diameter of the base of the branch pipe on the main pipe side is the same as the outer diameter of the branch opening on the opposite side of the main pipe, the branch pipe can be inserted from the branch opening to the base into the pipe to be connected. This allows the length of the branch pipe to be shortened while still ensuring an insertion margin into the pipe to be connected. This makes it possible to reduce the size. Furthermore, although it is made of synthetic resin, a reinforcing section that bulges toward the inside of the pipe is provided at the intersection where the main pipe and branch pipe intersect, ensuring the strength of the intersection, which is weak in strength. Furthermore, because the outer diameter of the main pipe and branch pipe is 60 mm or more, it is easy to ensure a sufficient flow rate.

[0008] <2> The aforementioned <1> In the pipe fitting according to the present invention, the SDR value, which is the ratio of the outer diameter to the wall thickness, is preferably 13.5 or less. In this way, since the SDR value, which is the ratio of the outer diameter to the wall thickness, is 13.5 or less, when a fluid flows inside, the tube can withstand the internal pressure of the fluid well.

[0009] <3> The aforementioned <1> In the pipe joint according to the above aspect, it is preferable that the outer diameter of the branch base portion on the branch pipe portion side of the main pipe portion is the same as the outer diameter of the main pipe opening portion. In this way, the outer diameter of the branch base on the branch pipe side of the main pipe is the same as the outer diameter of the main pipe inlet on the opposite side of the branch pipe, so the main pipe from the main pipe inlet to the branch base can be inserted into the pipe to be connected. Therefore, the length of the main pipe can be shortened while ensuring an insertion margin into the pipe to be connected. This allows for further miniaturization.

[0010] <4> The aforementioned <1> The pipe joint according to the present invention is preferably made of a polyolefin-based synthetic resin. In this way, it is highly effective to form a reinforcing section that bulges inward at the intersection where the main pipe section and branch pipe section intersect, which are made of a relatively soft polyolefin-based synthetic resin and therefore have weak strength.

[0011] <5> The aforementioned <4> In the pipe joint according to the above, it is preferable that the thickness of the portion where the reinforcing portion is provided is 1.5 times or more the thickness of the portion where the reinforcing portion is not provided. In this way, by making the thickness of the part where the reinforcing part is provided at least 1.5 times the thickness of the part where the reinforcing part is not provided, it is possible to sufficiently reinforce the intersection where the main pipe part and the branch pipe part intersect, which are weak in strength because they are made of a relatively soft polyolefin-based synthetic resin.

[0012] <6> The aforementioned <1> In the pipe joint according to the present invention, the reinforcing portion is formed on the entire inner periphery of the branch pipe portion on the side of the main pipe portion, and it is preferable that the reinforcing portion is formed on the entire inner periphery of the main pipe portion on the side of the branch pipe portion. In this way, the reinforcing portion is formed on the entire inner periphery of the branch pipe portion on the main pipe portion side, and on the entire inner periphery of the main pipe portion on the branch pipe portion side, so that the intersection portion where the main pipe portion and the branch pipe portion intersect, which is weak in strength, can be sufficiently reinforced.

[0013] <7> The aforementioned <1> ~ <6> It is preferable that the pipe joint according to the present invention is used for a rehabilitation pipe housed inside an existing pipe. This allows the pipe joint to be made smaller, making it easier to insert the pipe joint into the interior of the existing piping, improving the ease of installation of the rehabilitation piping including the pipe joint. [Effects of the Invention]

[0014] As described above, the present invention has the effect of enabling miniaturization. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing a piping structure including a pipe fitting according to an embodiment of the present invention. [Figure 2]1 is a cross-sectional view illustrating a piping installation method according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view illustrating a piping installation method according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view illustrating a piping installation method according to an embodiment of the present invention. [Figure 5] 1 is a cross-sectional view illustrating a piping installation method according to an embodiment of the present invention. [Figure 6] FIG. 10 is a cross-sectional view showing a modified example of a piping structure including a pipe joint according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a pipe joint and a piping installation method according to an embodiment of the present invention will be described with reference to the drawings.

[0017] 1, the pipe fitting 11 according to this embodiment constitutes a pipe for pumping a fluid, and has a cylindrical main pipe section 12, one branch pipe section 13 that branches radially outward from the axial middle section of the main pipe section 12, and a reinforcing section 15 that is provided at an intersection 14 where the main pipe section 12 and the branch pipe section 13 intersect and that bulges outward inward from the main pipe section 12 and the branch pipe section 13. The pipe fitting 11 is a T-shaped tee.

[0018] The pipe joint 11 is made of synthetic resin and is molded seamlessly as a single piece by cutting or injection molding. Specifically, the pipe joint 11 is made of a polyolefin-based synthetic resin such as polyethylene.

[0019] The main pipe section 12 has a first pipe section 21 on one side and a second pipe section 22 on the other side, with the branch pipe section 13 in between in the axial direction.

[0020] The first pipe section 21 of the main pipe section 12 has a first main pipe opening 31 (main pipe opening) on ​​the opposite side of the branch pipe section 13 in the axial direction, and a first branch base 32 (branch base) on the branch pipe section 13 side in the axial direction. The first main pipe opening 31 and the first branch base 32 are coaxial and have the same outer diameter, and are continuous without any steps. In other words, the first pipe section 21 has a first pipe section outer peripheral surface 33 on the radially outer side that is cylindrical and has a constant outer diameter over the entire axial length.

[0021] The reinforcing section 15 has a first pipe reinforcing section 41 that bulges radially inward, i.e., toward the inside of the pipe, on the inner periphery of the first pipe 21 on the branch pipe 13 side in the axial direction. The first pipe reinforcing section 41 is formed on the entire inner periphery of the part of the first pipe 21 on the branch pipe 13 side in the axial direction. The part of the first pipe 21 opposite the branch pipe 13 in the axial direction of the first pipe 21 has a continuous annular shape around the entire circumference of the first pipe 21.

[0022] The first pipe section inner surface 34, which is radially inward on the opposite side of the branch pipe section 13 from the first pipe section reinforcing section 41 in the axial direction of the first pipe section 21, has a cylindrical surface shape that is continuous around the entire circumference of the first pipe section 21.

[0023] The first pipe section reinforcement section 41 has a first pipe section reinforcement section tapered surface 42 on the radially inward side of the first pipe section inner peripheral surface 34 in the axial direction, and has a first pipe section reinforcement section inner end surface 43 on the radially inward side of the first pipe section reinforcement section tapered surface 42 on the opposite side of the first pipe section inner peripheral surface 34 in the axial direction.

[0024] The first pipe section reinforcement tapered surface 42 extends, while decreasing in diameter, from the end of the first pipe section inner peripheral surface 34 on the axial side of the branch pipe section 13 toward the branch pipe section 13. The first pipe section reinforcement tapered surface 42 is a tapered surface that continues around the entire circumference.

[0025] The first pipe section reinforcement inner end surface 43 is a cylindrical surface that extends from an end of the first pipe section reinforcement tapered surface 42 on the axial side opposite the first pipe section inner circumferential surface 34 to the axial side opposite the first pipe section inner circumferential surface 34. The first pipe section reinforcement inner end surface 43 has a cylindrical surface shape that is continuous over the entire circumference on the axial side of the first pipe section reinforcement tapered surface 42.

[0026] The first pipe section reinforcement inner end surface 43, the first pipe section reinforcement tapered surface 42, and the first pipe section inner circumferential surface 34 are arranged coaxially, and the inner diameter of the first pipe section reinforcement inner end surface 43 is smaller than the inner diameter of the first pipe section inner circumferential surface 34. The first pipe section reinforcement inner end surface 43, the first pipe section reinforcement tapered surface 42, and the first pipe section inner circumferential surface 34 are also arranged coaxially with the first pipe section outer circumferential surface 33.

[0027] In the pipe fitting 11, the portion of the first pipe section 21 where the first pipe section reinforcing section 41 is not provided is a cylindrical first thin-walled section 46, and the first pipe section inner circumferential surface 34 is formed in this first thin-walled section 46. In the pipe fitting 11, the portion of the first pipe section 21 where the first pipe section reinforcing section 41 is provided and the combined portion of the first pipe section reinforcing section 41 is a cylindrical first thick-walled section 47 that is thicker than the first thin-walled section 46, and the first pipe section reinforcing section tapered surface 42 and the first pipe section reinforcing section inner end surface 43 are formed in this first thick-walled section 47.

[0028] The second pipe section 22 of the main pipe section 12 has a second main pipe opening 51 (main pipe opening) on ​​the opposite side of the branch pipe section 13 in the axial direction, and a second branch base 52 (branch base) on the branch pipe section 13 side in the axial direction. The second main pipe opening 51 and the second branch base 52 are coaxial and have the same outer diameter, and are continuous without any steps. In other words, the second pipe section 22 has a second pipe section outer peripheral surface 53 on the radially outer side that is cylindrical and has a constant outer diameter over the entire axial length.

[0029] The second pipe outer surface 53 of the second pipe 22 and the first pipe outer surface 33 of the first pipe 21 are coaxial and have the same diameter, and are continuous without any steps. The second pipe 22 and the first pipe 21 are coaxial and have the same outer diameter, and are continuous without any steps. In other words, the main pipe 12 has a constant outer diameter throughout its entire length. In yet another way, the main pipe 12 has the same outer diameters for the first branch base 32 and the second branch base 52 on the branch pipe 13 side and the first main pipe opening 31 and the second main pipe opening 51 on the opposite side from the branch pipe 13. In yet another way, the main pipe 12 has no steps on its outer periphery. The outer diameter of the main pipe 12 is preferably 60 mm or more. If the main pipe 12 has an outer diameter of 60 mm or more, it is easy to ensure a sufficient flow rate.

[0030] The reinforcing section 15 has a second pipe reinforcing section 61 that bulges radially inward, i.e., toward the inside of the pipe, on the inner periphery of the second pipe 22 on the branch pipe 13 side in the axial direction. The second pipe reinforcing section 61 is formed on the entire inner periphery of the part of the second pipe 22 on the branch pipe 13 side in the axial direction. The second pipe reinforcing section 61 has a continuous annular shape around the entire circumference of the second pipe 22 on the side of the second pipe 22 opposite the branch pipe 13 in the axial direction.

[0031] The second pipe section inner peripheral surface 54, which is radially inward on the opposite side of the branch pipe section 13 from the second pipe section reinforcing section 61 in the axial direction of the second pipe section 22, has a cylindrical surface shape that is continuous around the entire circumference of the second pipe section 22.

[0032] The second pipe portion 22 has a second pipe portion inner peripheral surface 54 coaxial with and has the same diameter as the first pipe portion inner peripheral surface 34 of the first pipe portion 21. In other words, the second pipe portion 22 and the first pipe portion 21 are coaxial with and have the same inner diameter.

[0033] The second pipe section reinforcement section 61 has a second pipe section reinforcement section tapered surface 62 on the radially inward side of the second pipe section inner peripheral surface 54 in the axial direction, and has a second pipe section reinforcement section inner end surface 63 on the radially inward side of the second pipe section reinforcement section tapered surface 62 on the opposite side of the second pipe section inner peripheral surface 54 in the axial direction.

[0034] The second pipe section reinforcement tapered surface 62 extends, while decreasing in diameter, from the end of the second pipe section inner peripheral surface 54 on the axial side of the branch pipe section 13 toward the branch pipe section 13. The second pipe section reinforcement tapered surface 62 is a tapered surface that continues around the entire circumference.

[0035] The second pipe section reinforcement inner end surface 63 is a cylindrical surface that extends from the end of the second pipe section reinforcement tapered surface 62 on the axial side opposite the second pipe section inner circumferential surface 54 to the axial side opposite the second pipe section inner circumferential surface 54. The part of the second pipe section reinforcement inner end surface 63 on the axial side of the second pipe section reinforcement tapered surface 62 is a cylindrical surface that is continuous over the entire circumference.

[0036] The second pipe section reinforcement portion inner end surface 63, the second pipe section reinforcement portion tapered surface 62, and the second pipe section inner circumferential surface 54 are arranged coaxially, and the inner diameter of the second pipe section reinforcement portion inner end surface 63 is smaller than the inner diameter of the second pipe section inner circumferential surface 54. The second pipe section reinforcement portion inner end surface 63, the second pipe section reinforcement portion tapered surface 62, and the second pipe section inner circumferential surface 54 are also arranged coaxially with the second pipe section outer circumferential surface 53.

[0037] The second pipe reinforcement portion inner end surface 63 of the second pipe reinforcement portion 61 and the first pipe reinforcement portion inner end surface 43 of the first pipe reinforcement portion 41 are coaxial and have the same diameter and are continuous without any steps. In other words, the second pipe reinforcement portion 61 and the first pipe reinforcement portion 41 are coaxial and have the same inner diameter and are continuous without any steps.

[0038] In the pipe fitting 11, the portion of the second pipe section 22 where the second pipe section reinforcing section 61 is not provided is a cylindrical second thin-walled section 66, and the second pipe section inner circumferential surface 54 is formed in this second thin-walled section 66. In addition, in the pipe fitting 11, the portion of the second pipe section 22 where the second pipe section reinforcing section 61 is provided and the combined portion of the second pipe section reinforcing section 61 is a cylindrical second thick-walled section 67 that is thicker than the second thin-walled section 66, and the second pipe section reinforcing section tapered surface 62 and the second pipe section reinforcing section inner end face 63 are formed in this second thick-walled section 67.

[0039] The branch pipe section 13 has a branch opening section 71 on the axially opposite side of the main pipe section 12, and a base section 72 on the axial side of the main pipe section 12. The branch opening section 71 and the base section 72 are coaxial and have the same outer diameter, and are continuous without any steps. In other words, the branch pipe section 13 has a branch pipe section outer surface 73 on the radially outer side that is cylindrical with a constant outer diameter over the entire axial length. In other words, the branch pipe section 13 has no steps on the outer periphery. The branch pipe section 13 preferably has an outer diameter of 60 mm or more. A branch pipe section 13 with an outer diameter of 60 mm or more easily ensures a sufficient flow rate. The branch pipe section outer surface 73 of the branch pipe section 13, at its end on the axially root section 72 side, is continuous with the first pipe section outer surface 33 of the first pipe section 21 of the main pipe section 12 and the second pipe section outer surface 53 of the second pipe section 22. The branch pipe section 13 extends perpendicularly from the main pipe section 12. The central axis of the branch pipe section outer surface 73 of the branch pipe section 13 is perpendicular to the central axes of the first pipe section outer surface 33 and the second pipe section outer surface 53 of the main pipe section 12.

[0040] The reinforcement section 15 has a branch pipe reinforcement section 81 that bulges radially inward, i.e., toward the inside of the pipe, on the inner periphery of the branch pipe section 13 on the main pipe section 12 side in the axial direction. The branch pipe reinforcement section 81 is formed on the entire inner periphery of the branch pipe section 13 on the main pipe section 12 side in the axial direction, and is continuous with the first pipe reinforcement section 41 and the second pipe reinforcement section 61 of the main pipe section 12. The branch pipe reinforcement section 81 has an annular shape that continues around the entire circumference of the branch pipe section 13 on the side opposite the main pipe section 12 in the axial direction of the branch pipe section 13.

[0041] The branch pipe inner peripheral surface 74, which is radially inward on the opposite side of the main pipe 12 from the branch pipe reinforcing portion 81 in the axial direction of the branch pipe 13, has a cylindrical surface shape that is continuous around the entire circumference of the branch pipe 13. The central axis of the branch pipe inner peripheral surface 74 of the branch pipe 13 is perpendicular to the central axes of the first pipe inner peripheral surface 34 and the second pipe inner peripheral surface 54 of the main pipe 12.

[0042] The branch pipe reinforcement section 81 has a branch pipe reinforcement section tapered surface 82 on the radially inward side on the axial side of the branch pipe section inner peripheral surface 74, and has a branch pipe reinforcement section inner end surface 83 on the radially inward side of the branch pipe reinforcement section tapered surface 82 on the opposite side of the axial side from the branch pipe section inner peripheral surface 74.

[0043] The branch pipe section reinforcement tapered surface 82 extends, while decreasing in diameter, from the end of the branch pipe section inner peripheral surface 74 on the axial side of the main pipe section 12 toward the main pipe section 12 in the axial direction. The branch pipe section reinforcement tapered surface 82 is a tapered surface that continues around the entire circumference.

[0044] The branch pipe section reinforcement section inner end surface 83 is a cylindrical surface that extends from the end of the branch pipe section reinforcement section tapered surface 82 on the axial side opposite the branch pipe section inner circumferential surface 74 to the side opposite the branch pipe section inner circumferential surface 74. The branch pipe section reinforcement section inner end surface 83, on the axial side of the branch pipe section reinforcement section tapered surface 82, is a cylindrical surface that continues around the entire circumference.

[0045] The branch pipe reinforcement inner end surface 83, the branch pipe reinforcement tapered surface 82, and the branch pipe inner circumferential surface 74 are arranged coaxially, and the inner diameter of the branch pipe reinforcement inner end surface 83 is smaller than the inner diameter of the branch pipe inner circumferential surface 74. The branch pipe reinforcement inner end surface 83, the branch pipe reinforcement tapered surface 82, and the branch pipe inner circumferential surface 74 are also arranged coaxially with the branch pipe outer circumferential surface 73.

[0046] The branch pipe reinforcement portion 81 is continuous with the first pipe reinforcement portion 41 and the second pipe reinforcement portion 61 of the main pipe portion 12. The branch pipe reinforcement portion inner end surface 83 of the branch pipe portion 13 is continuous at the end opposite the branch pipe reinforcement portion tapered surface 82 in the axial direction with the first pipe reinforcement portion inner end surface 43 of the first pipe portion 21 and the second pipe reinforcement portion inner end surface 63 of the second pipe portion 22 of the main pipe portion 12. In the reinforcement portion 15, the central axis of the branch pipe reinforcement portion inner end surface 83 is perpendicular to the central axes of the first pipe reinforcement portion inner end surface 43 and the second pipe reinforcement portion inner end surface 63.

[0047] In the pipe fitting 11, the portion of the branch pipe section 13 where the branch pipe section reinforcing section 81 is not provided is a branch thin-walled section 86, and the branch pipe section inner peripheral surface 74 is formed in this branch thin-walled section 86. In addition, in the pipe fitting 11, the portion of the branch pipe section 13 where the branch pipe section reinforcing section 81 is provided and the combined portion of the branch pipe section reinforcing section 81 is a branch thick-walled section 87 that is thicker than the branch thin-walled section 86, and the branch pipe section reinforcing section tapered surface 82 and the branch pipe section reinforcing section inner end face 83 are formed in this branch thick-walled section 87.

[0048] The reinforcing section 15 is formed on the entire inner circumference of the branch pipe section 13 on the main pipe section 12 side in the axial direction, and is also formed on the entire inner circumference of the main pipe section 12 on the branch pipe section 13 side in the axial direction, and is continuous from the entire inner circumference of the branch pipe section 13 on the main pipe section 12 side in the axial direction to the entire inner circumference of the first pipe section 21 of the main pipe section 12 on the branch pipe section 13 side in the axial direction and the entire inner circumference of the second pipe section 22 on the branch pipe section 13 side in the axial direction.

[0049] The inner opening 90 in the branch pipe 13 that opens into the main pipe 12 is formed on the entire periphery of the reinforcing portion 15 .

[0050] Here, the thickness of the first pipe portion 21, i.e., the thickness t1 of the first thin-walled portion 46, is the same as the thickness of the second pipe portion 22, i.e., the thickness t2 of the second thin-walled portion 66. The combined thickness of the first pipe portion 21 and the first pipe reinforcement portion 41, i.e., the thickness t3 of the first thick-walled portion 47, is the same as the combined thickness of the second pipe portion 22 and the second pipe reinforcement portion 61, i.e., the thickness t4 of the second thick-walled portion 67. The thickness t3 of the first thick-walled portion 47 and the thickness t4 of the second thick-walled portion 67 are greater than the thickness t1 of the first thin-walled portion 46 and the thickness t2 of the second thin-walled portion 66. Preferably, the thickness t3 of the first thick-walled portion 47 is 1.5 times or more the thickness t1 of the first thin-walled portion 46, and the thickness t4 of the second thick-walled portion 67 is 1.5 times or more the thickness t2 of the second thin-walled portion 66. That is, in the pipe fitting 11, the thickness t3 of the first thick-walled portion 47 provided with the reinforcing portion 15 of the main pipe portion 12 is preferably 1.5 times or more the thickness t1 of the first thin-walled portion 46 not provided with the reinforcing portion 15 of the main pipe portion 12, and the thickness t4 of the second thick-walled portion 67 provided with the reinforcing portion 15 of the main pipe portion 12 is preferably 1.5 times or more the thickness t2 of the second thin-walled portion 66 not provided with the reinforcing portion 15 of the main pipe portion 12.

[0051] The shortest axial length L1 of the first thick-walled portion 47 is equal to the shortest length L2 of the second thick-walled portion 67, and the inner diameter d1 of the first thin-walled portion 46 is equal to the inner diameter d2 of the second thin-walled portion 66. The shortest length L1 of the first thick-walled portion 47 is preferably equal to or greater than (d1) / 2, which is half the inner diameter d1 of the first thin-walled portion 46. The shortest length L2 of the second thick-walled portion 67 is preferably equal to or greater than (d2) / 2, which is half the inner diameter d2 of the second thin-walled portion 66.

[0052] Furthermore, the combined thickness of the branch pipe section 13 and the branch pipe section reinforcement section 81, i.e., the thickness t6 of the branch thick-walled section 87, is greater than the thickness t5 of the branch pipe section 13, i.e., the branch thin-walled section 86. Preferably, the thickness t6 of the branch thick-walled section 87 is 1.5 times or more the thickness t5 of the branch thin-walled section 86. That is, in the pipe fitting 11, the thickness t6 of the branch thick-walled section 87 of the branch pipe section 13 provided with the reinforcement section 15 is preferably 1.5 times or more the thickness t5 of the branch thin-walled section 86 of the branch pipe section 13 not provided with the reinforcement section 15.

[0053] The shortest axial length L3 of the branch thick-walled portion 87 is preferably equal to or greater than (d3) / 2, which is half the inner diameter d3 of the branch thin-walled portion 86.

[0054] The pipe fitting 11 preferably has an SDR value, which is the ratio of outer diameter to wall thickness (outer diameter / wall thickness), of 13.5 or less throughout. If the SDR value exceeds 13.5, the pipe wall becomes too thin and may not be able to withstand the internal pressure of the fluid when it flows inside. If the SDR value is too low, the pipe wall may become too thick and may not be able to ensure a sufficient flow rate. For this reason, the lower limit of the SDR value is preferably 6 or more, and more preferably 7.4 or more.

[0055] Generally, in pipe thickness design, for pipes with water flowing inside, the relationship that follows the Naday equation shown in equation (1) below is known to represent the tensile circumferential stress (tensile stress generated in the circumferential direction in the cross section of the pipe) generated in the pipe due to the internal water pressure. σ=P(Dt) / 2t …(1) formula In equation (1), σ is the tensile circumferential stress generated in the pipe (MPa), P is the internal water pressure (MPa), D is the outer diameter of the pipe (mm), and t is the thickness of the pipe (mm).

[0056] Based on the Naday equation mentioned above, it is preferable to design the pipe thickness so that the stress generated at the design internal pressure (maximum allowable stress) has a safety factor of 2 for the 50-year creep strength of polyethylene water distribution pipes. For example, this relationship can be expressed by the following equation (2). σ 50 / S1=P d (Dt) / 2t …(2) formula However, in equation (2), σ 50 : 50-year creep strength of polyethylene water distribution pipe (10 MPa), S1: σ 50 Safety factor for (here assumed to be 2), P d : Maximum allowable pressure (hydrostatic pressure 0.75 x water hammer pressure 0.25 = 1.0 PMa) By modifying the above equation (2), the value of SDR (Standard Dimension Ratio) can be calculated using the following equation (3). SDR=D / t=1+(2σ 50 ) / P d ·S1=1+(2×10) / (1×2)=11…(3) formula

[0057] According to the pipe thickness design for water pipes, which was calculated with the aforementioned safety factor of 2, it is clear that an SDR value of 11 is preferable, but if the purpose is to rehabilitate pipes such as polyethylene sewer pipes, where the internal pressure of the pipe can be estimated to be low, an SDR value of 13.5 or less is desirable. Furthermore, if the standard SDR value for polyethylene water pipes is 11, the SDR value will be less than SDR6 when the flow rate drops by 40% (calculated based on a flow velocity coefficient of 140 and a hydraulic gradient of 3%), so an SDR value of 6 or more is preferable.

[0058] Using the pipe fitting 11 configured as described above, a piping structure connecting a first pipe 101, a second pipe 102, and a third pipe 103, all of which are made of synthetic resin, can be achieved, for example, by first inserting the first pipe 101 into the pipe fitting 11 from the branch opening 71 to the base 72 of the branch pipe section 13. At this time, the first pipe 101 is fitted over the branch opening 71 until it abuts against the main pipe section 12. Thus, the branch opening 71 serves as an insertion port. Next, the second pipe 102 is fitted into the pipe fitting 11 from the first main pipe opening 31 to the first branch base 32 of the first pipe section 21. At this time, the second pipe 102 is fitted over the first main pipe opening 31 until it abuts against the first pipe 101. Thus, the first main pipe opening 31 serves as an insertion port. Additionally, the third pipe 103 is inserted into the pipe fitting 11 by inserting the second pipe section 22 from the second main pipe port 51 to the second branch base 52. At this time, the third pipe 103 is fitted over the second main pipe port 51 until it abuts the first pipe 101. Therefore, the second main pipe port 51 becomes an insertion port. By using such a piping structure, the pipe fitting 11 can minimize the axial length of the branch pipe section 13 while ensuring an insertion allowance L0 into the first pipe 101. Here, we have taken the example of a case where the branch outlet 71 of the branch pipe section 13, the first main pipe outlet 31 of the first pipe section 21 of the main pipe section 12, and the second main pipe outlet 51 of the second pipe section 22 are all insertion ports, but it is sufficient if any one of the branch outlet 71 of the branch pipe section 13, the first main pipe outlet 31 of the first pipe section 21 of the main pipe section 12, and the second main pipe outlet 51 of the second pipe section 22 is an insertion port.

[0059] According to the pipe fitting 11 described above, the branch pipe 13 has the same outer diameter as the base 72 on the main pipe 12 side and the branch opening 71 on the opposite side from the main pipe 12. This allows the branch pipe 13 to be inserted from the branch opening 71 to the base 72 into the first pipe 101 to be connected. Therefore, the length of the branch pipe 13 can be shortened while ensuring an insertion allowance L0 into the first pipe 101 to be connected. This allows the pipe fitting 11 to be miniaturized. Furthermore, although the pipe fitting 11 is made of synthetic resin, the reinforcing portion 15 that bulges inward at the intersection 14 where the main pipe 12 and the branch pipe 13 intersect can be provided with sufficient strength. This ensures the strength of the intersection 14, which is weak in strength. As a result, the pipe fitting 11 can improve durability when used in pipes that are subject to internal pressure, such as waterworks pipes, gas pipes, and sewerage pipes that pump fluids. Furthermore, if the outer diameter of the main pipe section 12 and the branch pipe section 13 is 60 mm or more, it is easy to ensure a sufficient flow rate.

[0060] Furthermore, the pipe fitting 11 has an SDR value, which is the ratio of the outer diameter to the wall thickness, of 13.5 or less, and therefore can withstand the internal pressure of the fluid when the fluid flows inside.

[0061] Furthermore, in the pipe fitting 11, the outer diameter of the first branch base 32 on the branch pipe 13 side of the main pipe 12 is the same as the outer diameter of the first main pipe opening 31 on the opposite side of the branch pipe 13. This allows the main pipe 12 from the first main pipe opening 31 to the first branch base 32 to be inserted into the second pipe 102 to be connected. This allows the length of the main pipe 12 to be shortened while ensuring an insertion margin into the second pipe 102 to be connected. This allows the pipe fitting 11 to be further miniaturized. It is also possible for the outer diameter of the first branch base 32 on the branch pipe 13 side of the main pipe 12 to be different from the outer diameter of the first main pipe opening 31 on the opposite side of the branch pipe 13.

[0062] Furthermore, in the pipe fitting 11, the outer diameter of the second branch base 52 on the branch pipe 13 side of the main pipe 12 is the same as the outer diameter of the second main pipe opening 51 on the opposite side of the branch pipe 13, so that the main pipe 12 from the second main pipe opening 51 to the second branch base 52 can be inserted into the third pipe 103 to be connected. This allows the length of the main pipe 12 to be shortened while ensuring an insertion margin into the third pipe 103 to be connected. This allows the pipe fitting 11 to be further miniaturized. Note that the outer diameter of the second branch base 52 on the branch pipe 13 side of the main pipe 12 can also be different from the outer diameter of the second main pipe opening 51 on the opposite side of the branch pipe 13.

[0063] Furthermore, since the pipe fitting 11 is made of a relatively soft polyolefin-based synthetic resin, it is highly effective to form a reinforcing section 15 that bulges toward the inside of the pipe at the intersection 14 where the main pipe section 12 and the branch pipe section 13 intersect, which are weak in strength.

[0064] Furthermore, the pipe fitting 11 has a thickness of the first thick-walled portion 47 provided with the reinforcing portion 15 that is at least 1.5 times the thickness of the first thin-walled portion 46 that is not provided with the reinforcing portion 15, a thickness of the second thick-walled portion 67 provided with the reinforcing portion 15 that is at least 1.5 times the thickness of the second thin-walled portion 66 that is not provided with the reinforcing portion 15, and a thickness of the branch thick-walled portion 87 provided with the reinforcing portion 15 that is at least 1.5 times the thickness of the branch thin-walled portion 86 that is not provided with the reinforcing portion 15. This makes it possible to sufficiently reinforce the intersection 14 where the main pipe portion 12 and the branch pipe portion 13 intersect, which is weak in strength because it is made of a relatively soft polyolefin-based synthetic resin.

[0065] Furthermore, in the pipe fitting 11, the reinforcing section 15 is formed on the entire inner periphery of the branch pipe section 13 on the main pipe section 12 side, and on the entire inner periphery of the main pipe section 12 on the branch pipe section 13 side, so that the intersection section 14 where the main pipe section 12 and the branch pipe section 13 intersect, which is weak in strength, can be sufficiently reinforced.

[0066] In addition, in the pipe fitting 11, the reinforcement portion 15 has a first pipe portion reinforcement portion tapered surface 42, a second pipe portion reinforcement portion tapered surface 62, and a branch pipe portion reinforcement portion tapered surface 82 at the end side in the pipeline direction, so that pressure loss due to the provision of the reinforcement portion 15 can be suppressed.

[0067] Although the pipe fitting 11 has been described using as an example a structure in which one branch pipe section 13 branches off vertically from the middle position in the axial direction of the main pipe section 12, the present invention is also applicable to a structure in which at least one other branch pipe section branches off from, for example, the same position in the axial direction of the main pipe section 12 as the branch pipe section 13, but in a different vertical direction from the branch pipe section 13. The present invention is also applicable to a structure in which at least one branch pipe section branches off from the middle position in the axial direction of the main pipe section 12 at an angle other than perpendicular to the main pipe section 12 (a so-called Y-tee).

[0068] Next, we will explain an example of a method for installing the pipe fitting 11. In this example, the pipe fitting 11 is used for a rehabilitation pipe that is housed inside an existing pipe 110 as shown in Figure 2. In other words, this example of an installation method is a pipe-in-pipe method.

[0069] For example, as shown in Figure 2, when laying a rehabilitation pipe along the same route as the existing pipe 110, the existing pipe 110 has an existing main pipe 121 and an existing branch pipe 122 that branches off perpendicularly to the existing main pipe 121 from an intermediate position of the existing main pipe 121, the pipe fitting 11 is inserted from one side or the opposite side of the existing branch pipe 122 in the axial direction of the existing main pipe 121. In this case, because the length of the branch pipe 13 protruding from the main pipe 12 is limited as described above, the pipe fitting 11 can be smoothly inserted and placed into the existing main pipe 121 by aligning the axial direction of the main pipe 121 with the axial direction of the existing main pipe 121.

[0070] 3, the position of the branch pipe section 13 of the pipe fitting 11 in the axial direction of the existing main pipe section 121 is aligned with the existing branch pipe section 122, and the position of the branch pipe section 13 in the circumferential direction of the existing main pipe section 121 is aligned with the existing branch pipe section 122. With this in mind, the first pipe 101 is inserted from the existing branch pipe section 122 and fitted into the branch pipe section 13 of the pipe fitting 11. At this time, the first pipe 101 is fitted until it abuts against the main pipe section 12 of the pipe fitting 11. At this time, the first pipe 101 and the branch pipe section 13 of the pipe fitting 11 are bonded together using, for example, an adhesive.

[0071] Next, as shown in Fig. 4, the second pipe 102 is inserted into the existing main pipe section 121 from one axial side and fitted to the first pipe section 21 of the pipe fitting 11. At this time, the second pipe 102 is fitted until it abuts against the first pipe 101 that has been previously connected to the pipe fitting 11. At this time, the second pipe 102 and the first pipe section 21 of the pipe fitting 11 are bonded together using, for example, an adhesive.

[0072] Next, as shown in Fig. 5, the third pipe 103 is inserted into the existing main pipe section 121 from the other axial side and fitted to the second pipe section 22 of the pipe fitting 11. At this time, the third pipe 103 is fitted until it abuts against the first pipe 101 that has been previously connected to the pipe fitting 11. At this time, the third pipe 103 and the second pipe section 22 of the pipe fitting 11 are bonded together using, for example, an adhesive.

[0073] As described above, for the existing piping 110 having the existing main pipe section 121 and the existing branch pipe section 122 branching perpendicularly from the existing main pipe section 121 at an intermediate position of the existing main pipe section 121, the second pipe 102 and the third pipe 103 are arranged within the existing main pipe section 121, and the first pipe 101 is arranged within the existing branch pipe section 122, and these are connected by the pipe joint 11. Therefore, the rehabilitation pipe 111 can be arranged along the same route as the existing piping 110 within the existing piping 110 having the existing main pipe section 121 and the existing branch pipe section 122 branching perpendicularly from the existing main pipe section 121 at an intermediate position of the existing main pipe section 121.

[0074] As in the above construction method, if the pipe fitting 11 is used for a rehabilitation pipe 111 that is housed inside the existing pipe 110, the pipe fitting 11 can be made smaller, so that the pipe fitting 11 can be easily inserted inside the existing pipe 110, improving the construction efficiency of the rehabilitation pipe 111 that includes the pipe fitting 11.

[0075] The rehabilitation pipe 111 using the pipe joint 11 can be applied when the existing pipe 110 is buried underground, and can also be applied when the existing pipe 110 is not underground but is installed under a structure or along a bridge, etc. Furthermore, the pipe joint 11 can also be used for pipes other than the rehabilitation pipe 111 housed within the existing pipe 110.

[0076] Furthermore, instead of bonding the pipe fitting 11 to the first pipe 101, the second pipe 102, and the third pipe 103 with an adhesive, it is also possible to embed a coil in the connection portion of the first pipe 101, the second pipe 102, and the third pipe 103 to the pipe fitting 11 and join them by electric fusion. For example, as shown in Fig. 6, a first pipe 101A is prepared, having a socket 101a formed at its end and a coil 101b for electric fusion embedded inside the socket 101a. The socket 101a of the first pipe 101A is then inserted externally onto the pipe fitting 11 with the branch pipe section 13 inserted inside. Electricity is supplied to the coil 101b via terminal 101c to generate heat, thereby fusing the inner periphery of the socket 101a and the outer periphery of the branch pipe section 13. Similarly, a second pipe 102A is prepared, which has a socket 102a formed at its end and a coil 102b for electrical fusion embedded on the inner periphery of this socket 102a. The socket 102a of this second pipe 102A is inserted onto the pipe fitting 11 so that the first pipe section 21 is inserted inside, and electricity is supplied to the coil 102b via terminal 102c to generate heat, thereby fusing the inner periphery of the socket 102a and the outer periphery of the first pipe section 21 together. Similarly, a third pipe 103A is prepared, which has a socket 103a formed at its end and a coil 103b for electrical fusion embedded on the inner periphery of this socket 103a. The socket 103a of this third pipe 103A is inserted onto the pipe fitting 11 so that the second pipe section 22 is inserted inside. Electricity is supplied to the coil 103b via terminal 103c, causing it to generate heat, thereby fusing the inner periphery of the socket 103a and the outer periphery of the second pipe section 22 together.

[0077] Alternatively, the end face of the branch opening 71 of the branch pipe 13 opposite the main pipe 12 may be joined to the end face of the piping by butt welding, in which the end face is heated and melted, and then pressure-welded to fuse. Similarly, the end face of the first main pipe opening 31 of the first pipe 21 of the main pipe 12 opposite the branch pipe 13 may be joined to the end face of the piping by butt welding. Similarly, the end face of the second main pipe opening 51 of the second pipe 22 of the main pipe 12 opposite the branch pipe 13 may be joined to the end face of the piping by butt welding. [Explanation of symbols]

[0078] 11...pipe fitting, 12...main pipe section, 13...branch pipe section, 14...intersection section, 15...reinforcement section, 31...first main pipe opening section (main pipe opening section), 32...first branch base section (branch base section), 51...second main pipe opening section (main pipe opening section), 52...second branch base section (branch base section), 71...branch opening section, 72...root section, 110...existing pipe, 111...rehabilitation pipe.

Claims

1. A pipe joint made of synthetic resin, having at least one branch pipe section branching off from a main pipe section, for pumping a fluid, The main pipe section and the branch pipe section have an outer diameter of 60 mm or more, At least one of a branch opening portion of the branch pipe portion opposite to the main pipe portion and a main pipe opening portion of the main pipe portion opposite to the branch pipe portion is an insertion port, The branch pipe portion is The outer diameter of the base portion on the main pipe side and the outer diameter of the branch opening portion are the same diameter, A pipe joint in which a reinforcing portion is provided at an intersection where the main pipe portion and the branch pipe portion intersect, the reinforcing portion bulging out further toward the inside of the pipe than the main pipe portion and the branch pipe portion.

2. 2. A pipe joint according to claim 1, wherein the SDR value, which is the ratio of the outer diameter to the wall thickness, is 13.5 or less.

3. 2. The pipe joint according to claim 1, wherein the main pipe portion has an outer diameter of a branch base portion on the branch pipe portion side equal to an outer diameter of the main pipe opening portion.

4. 2. A pipe joint according to claim 1, which is made of a polyolefin-based synthetic resin.

5. 5. A pipe joint according to claim 4, wherein the thickness of the portion where the reinforcing portion is provided is at least 1.5 times the thickness of the portion where the reinforcing portion is not provided.

6. 2. The pipe joint according to claim 1, wherein the reinforcing portion is formed on the entire inner periphery of the branch pipe portion on the side of the main pipe portion, and is formed on the entire inner periphery of the main pipe portion on the side of the branch pipe portion.

7. A piping installation method in which the pipe joint according to any one of claims 1 to 6 is used for rehabilitation piping housed inside an existing piping.

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