Pipe fittings

Abstract

The present invention provides an inner core that can prevent detachment from the pipe and improve pull-out strength. [Solution] The pipe joint of the present disclosure comprises a joint body 101 having a receiving recess 106 into which a pipe is inserted from one side, retaining members 104a and 104b provided in the receiving recess 106 and in contact with the outer surface of the pipe to restrict the pipe from coming out, an inner core 105 having a cylindrical portion 105a that supports the pipe from the inside, and a flange portion 105b provided on its base end side and in contact with the end face 117 of the pipe, wherein a projection 105c is formed on the outer surface of the cylindrical portion 105a that contacts the inner surface of the pipe, and when the pipe is inserted into the receiving recess 106 with the inner core 105 installed on the pipe, the projection 105c is not formed on the outer surface of the cylindrical portion 105a corresponding to the installation positions of the retaining members 104a and 104b.

Description

Technical Field

[0001] The present invention relates to a pipe joint.

Background Art

[0002] An external water stop joint, which is a method of arranging a water stop packing of the joint outside the pipe and stopping water by the contact between the outside of the pipe and the packing, is known. Some pipe joints such as external water stop joints may include, in addition to a cylindrical joint body for connecting pipes, a member called an in-core. The in-core is inserted inside the end of the pipe and has a role of suppressing deformation of the pipe and maintaining watertightness between the packing and the pipe when the pipe is inserted into the joint body. <00 extraordinarily high.

[0003]

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the case of the inner core described in Patent Document 1, the protruding portion extends along the entire length of the inner core's tubular portion. Therefore, after the inner core is inserted into the pipe, the wall thickness of the pipe in contact with the protruding portion becomes thinner. When the wall thickness of the pipe in contact with the protruding portion is thin, the thin-walled portion of the pipe is more likely to stretch when the pipe is pulled, which could lead to a decrease in pull-out strength.

[0006] This invention has been made in consideration of these circumstances, and aims to provide an inner core that can suppress detachment from the pipe and improve pull-out strength. [Means for solving the problem]

[0007] To solve the above problems, this invention proposes the following means. (1) A pipe joint according to one aspect of the present disclosure comprises a joint body having a receiving recess into which a pipe is inserted from one side; an anti-slip member provided in the receiving recess and in contact with the outer surface of the pipe to restrict the pipe from coming out; an inner core having a cylindrical portion that supports the pipe from the inside and a flange portion provided at its base end and in contact with the end face of the pipe, wherein a projection is formed on the outer surface of the cylindrical portion that contacts the inner surface of the pipe, and when the pipe is inserted into the receiving recess with the inner core installed on the pipe, the projection is not formed on the outer surface of the cylindrical portion corresponding to the installation position of the anti-slip member. (2) Multiple projections may be formed on the outer circumferential surface of the cylindrical portion. (3) The outer diameter of the cylindrical portion at the position including the protrusion may be larger than the inner diameter of the pipe. (4) When the pipe is inserted into the receiving recess with the inner core installed in the pipe, the retaining member and the projection may be offset relative to the pipe axis of the joint body. [Effects of the Invention]

[0008] This invention provides an inner core that can suppress detachment from the pipe and improve pull-out strength. [Brief explanation of the drawing]

[0009] [Figure 1] This is a partially broken view of the pipe joint in this embodiment. [Figure 2] This is a cross-sectional view of the pipe joint in this embodiment. [Figure 3] This is a cross-sectional view of the inner core of the pipe fitting in this embodiment. [Figure 4A] This is a perspective view of the first example of the shape of the protrusion of the inner core. [Figure 4B] This is a cross-sectional view of the first example of the shape of the protrusion of the inner core. [Figure 5A] This is a perspective view of a second example of the shape of the protrusion of the inner core. [Figure 5B] This is a cross-sectional view of a second example of the shape of the protrusion of the inner core. [Figure 6A] This is a perspective view of a third example of the shape of the protrusion of the inner core. [Figure 6B] This is a cross-sectional view of a third example of the shape of the protrusion of the inner core. [Figure 7A] This is a perspective view of a fourth example of the shape of the protrusion of the inner core. [Figure 7B] This is a stepped view of the fourth example of the shape of the protrusion of the inner core. [Figure 8A] This is a perspective view of the fifth example of the shape of the protrusion of the inner core. [Figure 8B] This is a cross-sectional view of the fifth example of the shape of the protrusion of the inner core. [Modes for carrying out the invention]

[0010] Hereinafter, a pipe joint according to one embodiment of the present invention will be described with reference to the drawings.

[0011] Figure 1 shows a partial fracture diagram of pipe joint 100, which is an external waterproof joint. As shown in Figure 1, the pipe joint 100 (external watertight joint) comprises a cylindrical joint body 101 and a cap 102 provided at the end of the joint body 101.

[0012] Hereinafter, the direction along the central axis of the joint body 101 is referred to as the axial direction, and in a plan view of the joint body 101 viewed from the axial direction, the direction intersecting the central axis is referred to as the radial direction. Further, in the plan view, the direction of going around around the central axis is referred to as the circumferential direction.

[0013] On the inner peripheral surface at the axial end of the joint body 101, a step 113 is formed. The step 113 protrudes radially inward from the inner peripheral surface of the joint body 101. The step 113 is provided over the entire circumference in the circumferential direction. In the step 113, the inner diameter of the joint body 101 gradually (stepwise) decreases from the outer side in the axial direction to the inner side. An in-core 105 formed separately from the joint body 101 abuts against the step 113. Hereinafter, in the joint body 101, the portion from the end face of the joint body 101 to the step 113 is referred to as the open end of the joint body 101.

[0014] On the outer peripheral surfaces at both axial ends of the joint body 101, an outer flange portion 101b and a male screw portion 101c are formed. The outer flange portion 101b protrudes radially outward from the joint body 101. The outer flange portion 101b extends over the entire circumference on the outer peripheral surface of the joint body 101. The male screw portion 101c is formed in a portion of the outer peripheral surface of the joint body 101 that is located axially outside (that is, closer to the end of the joint body 101) than the outer flange portion 101b.

[0015] As shown in FIGS. 1 and 2, the cap 102 is a cylindrical shape whose outer diameter gradually decreases in the axial direction. The cap 102 includes a first cylinder 102a having an internal thread formed on its inner peripheral surface, and a second cylinder 102b located axially outside along the first cylinder 102a. The first cylinder 102a is screwed onto the male screw portion 101c. A step 102d is provided at a portion corresponding to the boundary between the first cylinder 102a and the second cylinder 102b on the inner circumference of the cap 102. The step 102d extends over the entire circumference in the circumferential direction. The step 102d contacts or is close to the end face of the joint body 101 facing axially outside.

[0016] The second cylinder 102b has a smaller diameter than the first cylinder 102a. The second cylinder 102b extends axially outward from the first cylinder 102a. In the pipe joint 100, a receiving recess 106 for accommodating the water-stopping portion 103 and the fixing portion 104 is formed between the joint body 101 and the cap 102. The receiving recess 106 is formed between the step 102d and the end face of the joint body 101 that faces outward in the axial direction. The receiving recess 106 extends around the entire circumference in the circumferential direction.

[0017] The joint body 101 is formed, for example, by injection molding or machining of a synthetic resin material. The cap 102 is formed, for example, by injection molding of a synthetic resin material or by machining, casting, or forging of a metal material. The aforementioned synthetic resin material can be arbitrarily selected based on quality design according to the application, for example, cross-linked polyethylene, polybutene, polyvinyl chloride (PVC), polysulfone resin (PSU), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyphenylsulfone resin (PPSU), polyphenylene sulfide resin (PPS), glass fiber reinforced PPS, polyvinylidene fluoride (PVDF), etc. Other processing methods such as cutting and fusion welding may also be used. The aforementioned metal materials can be arbitrarily selected based on the quality design required for the application, including stainless steel, low-alloy steel, carbon steel, low-temperature carbon steel, low-temperature alloy steel, brass, gunmetal, aluminum alloy, magnesium alloy, etc.

[0018] The base 103b is positioned between the packing 103a and the retaining member 104a. The base 103b restricts contact between the packing 103a and the retaining member 104a. The base 103b is formed in an annular shape. The base 103b extends around the entire circumference in the circumferential direction. The base 103b is fitted into the open end of the joint body 101. The base 103b is in contact with the axially outward-facing end of the first stage of the joint body 101. The base 103b is hooked onto the first stage of the joint body 101 from the axially outward side. The inner diameter of the base 103b is larger than the inner diameter of the packing 103a. The base 103b is formed, for example, by injection molding of a synthetic resin material or by machining, casting, or forging of a metal material. As the material for the packing 103a, rubber materials such as ethylene-propylene-diene rubber (EPDM), fluororubber (FKM), vinyl-methyl-silicone rubber (VMQ), acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and chloroprene rubber (CR) can be used.

[0019] The aforementioned synthetic resin material can be arbitrarily selected based on quality design according to the application, for example, cross-linked polyethylene, polybutene, polyvinyl chloride (PVC), polysulfone resin (PSU), polycarbonate resin (PC), polyamide resin (PA), polyacetal resin (POM), polyphenylsulfone resin (PPSU), polyphenylene sulfide resin (PPS), glass fiber reinforced PPS, polyvinylidene fluoride (PVDF), etc. Other processing methods such as cutting and fusion welding may also be used.

[0020] The aforementioned metal materials can be arbitrarily selected based on the quality design required for the application, including stainless steel, low-alloy steel, carbon steel, low-temperature carbon steel, low-temperature alloy steel, brass, gunmetal, aluminum alloy, magnesium alloy, etc. Furthermore, if the pipe joint 100 does not have a fixing portion 104, it does not need to have a base 103b.

[0021] The retaining members 104a, 104b and spacer 104c are positioned axially outward relative to the base 103b. The retaining members 104a, 104b and spacer 104c are positioned in the housing recess of the joint body 101. The retaining members 104a, 104b and spacer 104c are positioned to be movable with a slight amount of axial play relative to the housing recess. The retaining members 104a, spacer 104c, and retaining member 104b are positioned in this order from the axial outside to the inside. Spacer 104c is positioned axially sandwiched between the retaining members 104a and 104b in the housing recess. The retaining member 104a is provided in the housing recess and, when the pipe P is inserted into the pipe joint 100, contacts and bites into the outer surface of the pipe P, restricting the pipe P from coming out.

[0022] Figure 3 shows a cross-sectional view of the inner core 105. As shown in Figure 3, the inner core 105 comprises a cylindrical portion 105a that supports the pipe P from the inside, and a flange portion 105b provided on the base end side of the cylindrical portion 105a and in contact with the end face 117 of the pipe P. The cylindrical portion 105a is formed in a hollow cylindrical shape that extends in the axial direction, with both ends in the axial direction open. The outer diameter of the flange portion 105b is larger than the outer diameter of the cylindrical portion 105a. Of the two ends in the axial direction of the inner core 105, the end on which the flange portion 105b is provided is called the first inner core end, and the other end is called the second inner core 105 end. The cylindrical portion 105a may have a reduced diameter portion 107 at the end on the inner core second end side, where the outer diameter decreases as it moves from the inner core first end side toward the inner core second end side. As shown in Figure 2, the inner core 105 is positioned coaxially with the joint body 101. When connecting pipe P as shown in Figures 1 and 2, the inner core 105 is housed in the joint body 101, and the second end of the inner core is positioned axially outward relative to the first end of the inner core. The second end of the inner core is located inside the cap 102 (second cylinder). The first end of the inner core is located inside the joint body 101. The first end of the inner core is positioned axially inward from the packing 103a. The inner core 105 is located inside the packing 103a, base 103b, retaining member 104a, spacer 104c, and retaining member 104b.

[0023] As shown in Figure 3, a projection 105c is formed on the outer circumferential surface of the cylindrical portion 105a, which contacts the inner circumferential surface of the pipe P. The outer diameter of the cylindrical portion 105a at the position including the projection 105c is larger than the inner diameter of the pipe P. Multiple projections 105c may be formed on the outer circumferential surface of the cylindrical portion 105a. As shown in Figure 2, when the pipe P is inserted into the housing recess 106 with the inner core 105 positioned inside the pipe P, the protrusion 105c is not formed on the outer circumferential surface (region A) of the cylindrical portion 105a corresponding to the installation positions of the retaining members 104a and 104b in a cross-sectional view along the pipe axis of the joint body 101. In other words, when the pipe P is inserted into the housing recess 106 with the inner core 105 installed inside the pipe P, the retaining members 104a and 104b and the protrusion 105c are offset along the pipe axis of the joint body 101. As shown in Figure 3, the protrusion 105c is formed in region B (region B1 + B2), which is the region of the outer circumferential surface of the cylindrical portion 105a excluding the outer circumferential surface (region A) of the cylindrical portion 105a corresponding to the installation positions of the retaining members 104a and 104b. If the protrusion 105c is positioned in region A, the protrusion 105c and the retaining members 104a and 104b will bite into region A of the pipe P, reducing the wall thickness of the pipe P in region A and making it more prone to breakage. To suppress breakage of the pipe P in region A, the protrusion 105c is formed in region B (regions B1 + B2). Furthermore, by forming the protrusion 105c in region B (regions B1 + B2), it is possible to prevent only a portion of the pipe P from being excessively crushed by the retaining members 104a and 104b and the protrusion 105c. From the viewpoint of ensuring that the protrusion 105c bites into the pipe P, it is preferable that the protrusion 105c is not formed in region C of the outer circumferential surface of the cylindrical portion 105a where the reduced diameter portion 107 is provided.

[0024] In this embodiment, four protrusions 105c are provided. Specifically, as shown in Figure 3, they are provided in two rows in the direction of the pipe axis (one row each in regions B1 and B2), and in each row, two protrusions 105c are provided spaced 180° apart in the circumferential direction. The number of protrusions 105c is not limited, but from the viewpoint of ensuring tensile strength, it is preferable that the number of protrusions 105c be between four and eight. If the number of protrusions 105c is four or more, pull-out strength can be ensured. On the other hand, if the number of protrusions 105c is nine or more, the insertion resistance when inserting the inner core 105 into the pipe P may increase due to the protrusions 105c, reducing ease of installation. Therefore, it is preferable that the number of protrusions 105c be eight or less. The protrusions 105c only need to be formed in region B, and their arrangement is not limited to the above.

[0025] From the viewpoint of ensuring that the protrusions 105c bite into the pipe P, it is preferable that the protrusions 105c be arranged in one or more rows along the pipe axis, and that there be two or more protrusions 105c in the circumferential direction. The spacing of the circumferential protrusions 105c is not limited, but from the viewpoint of evenly distributing the stress on the contact portion between the pipe P and the protrusions 105c, it is preferable that the spacing of the circumferential protrusions 105c be equal. The spacing of the circumferential protrusions 105c may be, for example, 60°, 90°, or 180°.

[0026] For example, the protrusions 105c may be arranged in a single row in the axial direction of the pipe (one row in region B1 or B2), and four protrusions 105c may be arranged at 90° intervals in the circumferential direction.

[0027] Figures 4A and 4B show the shape of the projection 105c in this embodiment. As shown in Figure 4B, the shape of the projection 105c in the pipe joint 100 of this embodiment has a taper such that, in cross-sectional view, the thickness of the projection 105c decreases from the first end side of the inner core towards the second end side of the inner core. In this way, because the projection 105c has a taper in cross-sectional view, when inserting the inner core 105 into the pipe P, the projection 105c is inserted into the pipe P from the thinner side, so the inner core 105 can be easily inserted into the pipe P. Furthermore, when stress is applied to the inner core 105 inserted into the pipe P in the direction of pulling the inner core 105 out of the pipe P, the projection 105c of the inner core 105 bites into the inner circumferential surface of the pipe P, thereby preventing the inner core 105 from falling out. The projection 105c of this embodiment has a chamfered portion 115 on a part of the first end side of the inner core. If the inner core has a chamfered portion 115 on a part of the first end side, for example, the inner core 105 can be inserted into the pipe P smoothly.

[0028] The shape of the protrusion 105c is not limited to the above. For example, as shown in Figures 5A and 5B, in addition to the above configuration, the outer circumferential surface of the cylindrical portion 105a that is in contact with the first end of the inner core of the projection 105c may have a notch 116. For example, as shown in Figure 6B, in a cross-sectional view of the projection 105c, the angle between the end face 117 on the inner core first end side of the projection 105c and the outer circumferential surface of the cylindrical portion 105a does not have to be a right angle. Specifically, as shown in Figures 6A and 6B, the angle between the end face 117 on the inner core first end side of the projection 105c and the outer circumferential surface (notch 116) of the cylindrical portion 105a may be formed to be acute.

[0029] Furthermore, for example, the shape of the protrusion 105c may be approximately hemispherical. For example, as shown in Figures 7A and 7B, the shape of the projection 105c may be substantially hemispherical, and a part of the curved surface on the first end side of the in-core of the projection 105c may be interrupted, giving it an end face 117. For example, as shown in Figures 8A and 8B, the shape of the projection 105c may be substantially hemispherical, and the outer circumferential surface of the cylindrical portion 105a that is in contact with the first end side of the projection 105c may have a notch 116, and the angle between the end face 117 on the first end side of the projection 105c and the outer circumferential surface (notch 116) of the cylindrical portion 105a may be formed to be acute. [Examples]

[0030] (Example 1) We investigated the difference in pull-out strength between a pipe fitting using an inner core without protrusions (comparative example) and a pipe fitting using an inner core with four protrusions (inventive example). Furthermore, a tensile test was conducted using a φ13 pipe fitting. Test conditions: A sample with a pipe fitting and pipe connected was subjected to tensile testing at 20 mm / min using a Tensilon universal testing machine. Test sample: Metal male adapter + 250mm pipe + pipe fitting with two retaining rings + 250mm pipe + metal male adapter

[0031] As a result, the pipe joint using an inner core without protrusions (comparative example) had a pull-out strength (tensile strength) of 1.40 kN, while the pipe joint using an inner core with four protrusions (inventive example) had a pull-out strength (tensile strength) of 1.60 kN. In other words, the inventive example showed higher pull-out strength compared to the comparative example. Therefore, in order to improve the pull-out strength, it became clear that the pipe joint should have the structure of the inventive example, in which four protrusions are formed, rather than the structure of the comparative example, in which no protrusions are formed.

[0032] (Example 2) As mentioned earlier, there is a trade-off between the pull-out strength of the pipe fitting and the ease of attaching the inner core to the pipe. Therefore, we investigated the relationship between the pull-out strength of the pipe fitting and the ease of attachment as a result of changing the number of protrusions.

[0033] We prepared two types of pipe fittings: one using an inner core without protrusions (comparative example) and another using an inner core with protrusions (inventive example). For the pipe fittings using inner cores with protrusions, we prepared and tested those with 2, 4-8, and 9 or more protrusions.

[0034] In evaluating the pull-out strength, the tensile test conditions were the same as in Example 1. The pull-out strength was evaluated as follows. A: Tensile strength of 1.60kN or more B: Tensile strength of 1.42kN or more C: Tensile strength of 1.42kN or less For tensile strength, a rating of B or higher was considered acceptable.

[0035] Ease of application was compared through sensory testing. The evaluation of ease of application was carried out as follows: A: Can be worn without resistance. B: Although there is some resistance, it can be easily attached. C: High resistance, making installation difficult or impossible.

[0036] Furthermore, the likelihood of the inner core detaching after installation was also evaluated. This was done by inserting the inner core into the pipe and then shaking the pipe to check whether or not the inner core detached from the pipe.

[0037] The results are shown in Table 1.

[0038] [Table 1]

[0039] The pipe fitting using an inner core with zero protrusions received an A rating for ease of installation, but failed to meet the requirements due to a C rating for pull-out strength. Furthermore, the inner core of the pipe fitting with zero protrusions easily detached from the pipe after installation. Pipe fittings using inner cores with 1 to 3 protrusions received a rating of B for both pull-out strength and ease of installation. Furthermore, the inner cores of pipe fittings using inner cores with 1 to 3 protrusions did not easily detach from the pipe after installation. Pipe fittings using inner cores with 4 to 8 protrusions all received an A rating for pull-out strength and a B rating for ease of installation, demonstrating superior pull-out strength compared to pipe fittings using inner cores with 2 protrusions. Furthermore, the inner cores of pipe fittings with 4 to 8 protrusions did not easily detach from the pipe after installation.

[0040] On the other hand, pipe fittings using inner cores with 9 or more protrusions all received an A rating for pull-out strength, but received a C rating for ease of installation. This was inferior to pipe fittings using inner cores with 2 or 4-8 protrusions in terms of ease of installation. However, the inner core of the pipe fittings with 9 protrusions did not easily detach from the pipe after installation.

[0041] Therefore, it became clear that in order to improve tensile strength while ensuring ease of installation, it is preferable for the pipe joint to have a structure in which four to eight protrusions are formed.

[0042] As described above, the pipe joint 100 of the present disclosure comprises a joint body 101 having a receiving recess 106 into which a pipe is inserted from one side, retaining members 104a and 104b provided in the receiving recess 106 and in contact with the outer surface of the pipe to restrict the pipe from coming out, an inner core 105 having a cylindrical portion 105a that supports the pipe from the inside, and a flange portion 105b provided on its base end side and in contact with the end face 117 of the pipe, wherein a projection 105c is formed on the outer surface of the cylindrical portion 105a that contacts the inner surface of the pipe, and when the pipe is inserted into the receiving recess 106 with the inner core 105 installed on the pipe, the projection 105c is not formed on the outer surface of the cylindrical portion 105a corresponding to the installation positions of the retaining members 104a and 104b. The pipe joint 100 (external watertight joint) consists of retaining members 104a and 104b and an inner core 105 that sandwich the outer and inner surfaces of the pipe, respectively. As a result, the retaining members 104a and 104b bite into the outer surface, ensuring the pull-out strength of the pipe and suppressing leakage of water and other liquids from inside the pipe. With the above configuration, when the retaining members 104a and 104b and the inner core 105 sandwich the outer and inner surfaces of the pipe, respectively, the retaining members 104a and 104b bite into the outer surface, and the protrusion 105c of the inner core 105 bites into the inner surface of the pipe. As a result, the points of contact are increased, with the contact points being the protrusion 105c of the inner core 105 against the pipe, in addition to the contact points between the retaining members 104a and 104b and the pipe. Therefore, the detachment of the inner core 105 can be suppressed compared to the conventional method, and the pull-out strength can be improved. Furthermore, the protrusion 105c is not formed on the outer surface of the cylindrical portion 105a corresponding to the installation positions of the retaining members 104a and 104b. As a result, it is possible to suppress excessive crushing of only a part of the pipe by the retaining members 104a and 104b and the protrusion 105c.

[0043] Furthermore, multiple protrusions 105c may be formed on the outer circumferential surface of the cylindrical portion 105a. With this configuration, since multiple protrusions 105c are formed, the number of points where the core bites into the pipe can be further increased. Therefore, the detachment of the inner core 105 can be further suppressed, and the pull-out strength can be further improved.

[0044] Furthermore, the outer diameter of the cylindrical portion 105a at the position including the protrusion 105c may be larger than the inner diameter of the pipe. With this configuration, the outer diameter of the cylindrical portion 105a at the position including the protrusion 105c is larger than the inner diameter of the pipe, so the protrusion 105c of the inner core 105 is pressed against the inner circumferential surface of the pipe. This ensures that the protrusion 105c of the inner core 105 bites securely into the inner circumferential surface of the pipe. Therefore, the detachment of the inner core 105 can be further suppressed, and the pull-out strength can be further improved. [Explanation of Symbols]

[0045] 100 Pipe Fittings 101 Fitting body 102 Cap 102a 1st tube 102b 2nd tube 103a Packing 103b Base 104a, 104b Retaining members 104c spacer 105 Incore 105a Cylindrical section 105b Tsubabe 105c protrusion 106 Receiving recess 107 Reduced diameter section 115 Chamfered section 116 Notch 117 End face Pipe P

Claims

1. A joint body having a receiving recess into which a pipe is inserted from one side, A retaining member is provided within the aforementioned recess and contacts the outer surface of the pipe to restrict the pipe from coming out, The inner core comprises a cylindrical portion that supports the pipe from the inside, and a flange portion provided at its base end that contacts the end face of the pipe. A projection is formed on the outer circumferential surface of the cylindrical portion, which contacts the inner circumferential surface of the pipe. When the pipe is inserted into the receiving recess with the inner core installed in the pipe, the protrusion is not formed on the outer circumferential surface of the cylindrical portion corresponding to the installation position of the retaining member. Pipe fittings.

2. Multiple projections are formed on the outer circumferential surface of the cylindrical portion. The pipe fitting according to claim 1.

3. The outer diameter of the cylindrical portion at the position including the protrusion is larger than the inner diameter of the pipe. The pipe fitting according to claim 1.

4. When the pipe is inserted into the receiving recess with the inner core installed in the pipe, the retaining member and the projection are offset relative to the pipe axis of the joint body. The pipe fitting according to claim 1.

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