Pipe Fittings

Abstract

To provide a pipe joint capable of preventing fragments of a positioning protrusion from giving harmful effects to water tightness.SOLUTION: A pipe joint 11 includes a locking mechanism 23 for retaining a resin pipe 51 on a joint body 12, and a seal ring 17 for securing water tightness between the joint body 12 and the resin pipe 51, the locking mechanism 23 including a metal lock ring 24, and a synthetic resin lock ring retainer 25 having the lock ring 24 arranged in a space encircled by a plurality of positioning protrusions 25a formed on the outer periphery part for centering the lock ring 24, the plurality of positioning protrusions 25a being arranged at predetermined spaces in the circumferential direction of the lock ring retainer 25. The circumferential length of the front end inner edge of the positioning protrusion 25a on the lock ring retainer 25 in the direction is set to be smaller than the predetermined space.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pipe joint of a type in which a lock ring is used to prevent a pipe from coming loose. [Background technology]

[0002] Fig. 22 shows a pipe joint 101 described in Patent Document 1. The pipe joint 101 includes a joint body 102, a retaining mechanism 103 for holding a plastic pipe 151 to the joint body 102, and a synthetic resin cap 104 for attaching the retaining mechanism 103 to the joint body 102. A seal ring 105 is disposed within the joint body 102 to ensure watertightness between the joint body 102 and the plastic pipe 151.

[0003] The retaining mechanism 103 includes a metal lock ring 106. The retaining mechanism 103 includes a synthetic resin lock ring holder 107 for positioning (centering) the lock ring 106. The cap 104 to which the lock ring 106 and the lock ring holder 107 are assembled is fitted onto the outside of the joint body 102 and fixed by snap engagement.

[0004] 22 and 23, positioning protrusions 107a are formed on the outer periphery of lock ring holder 107. Positioning protrusions 107a are arc-shaped extending along the circumferential direction of lock ring holder 107, and multiple positioning protrusions 107a are arranged at predetermined intervals in the circumferential direction of lock ring holder 107. Lock ring 106 is arranged in a space surrounded by the multiple positioning protrusions 107a. Lock ring holder 107 centers lock ring 106 by abutting and restricting relative movement of lock ring 106 in the radial direction with positioning protrusions 107a. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-167326 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the process of snapping the cap 104 into the joint body 102, the inner diameter of the cap 104 temporarily expands, which makes it easier for relative movement in the radial and axial directions to occur between the lock ring 106 and the lock ring holder 107. If the cap 104 is pressed strongly into the joint body 102 in a state in which radial and axial misalignment occurs between the lock ring 106 and the lock ring holder 107, the lock ring 106 may scrape off the lock ring holder 107, particularly the positioning protrusion 107a. If a large portion of the positioning protrusion 107a is scraped off and the resulting fragments get in between the plastic pipe 151 and the seal ring 105, the watertightness of the pipe joint 101 will decrease.

[0007] An object of the present invention is to provide a pipe joint which can prevent fragments of a positioning projection from adversely affecting watertightness. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the pipe fitting of the invention of claim 1 is a pipe fitting equipped with an anti-slip mechanism for holding a plastic pipe to the fitting body, and a seal ring for ensuring watertightness between the fitting body and the plastic pipe, wherein the anti-slip mechanism is a pipe fitting equipped with a metal lock ring and a lock ring holder made of synthetic resin in which the lock ring is positioned in a space surrounded by a plurality of positioning protrusions formed on the outer periphery for centering the lock ring, wherein the plurality of positioning protrusions are arranged at predetermined intervals in the circumferential direction of the lock ring holder, and the circumferential length of the inner edge of the tip of the positioning protrusions on the lock ring holder is set to be smaller than the predetermined interval. [Brief description of the drawings]

[0009] [Figure 1] FIG. [Diagram 2] FIG. 4 is a longitudinal sectional view illustrating a pipe joint in the middle of being assembled. [Diagram 3] 13 is an enlarged cross-sectional view of a main portion illustrating a state in which the lock ring is misaligned during assembly. FIG. [Figure 4] Front view of the lock ring retainer (for 16A). [Diagram 5] Rear view of the lock ring retainer (for 16A). [Figure 6] Right side view of the lock ring retainer (for 16A). [Figure 7] Left side view of the lock ring holder (for 16A). [Figure 8] Plan view of the lock ring retainer (for 16A). [Figure 9] Bottom view of the lock ring retainer (for 16A). [Figure 10] Front view of the lock ring holder (for 10A). [Figure 11] Front view of the lock ring retainer (for 13A). [Figure 12] Front view of the lock ring holder (for 20A). [Figure 13] Front view of the lock ring holder (for 25A). [Figure 14] FIG. [Figure 15] FIG. 13 is a rear view of a lock ring retainer of another example. [Figure 16] FIG. 13 is a right side view of a lock ring retainer of a further example. [Figure 17] FIG. 13 is a left side view of a lock ring retainer of another example. [Figure 18] FIG. [Figure 19] FIG. 13 is a bottom view of a lock ring retainer of a further example. [Figure 20] FIG. 13 is a front view of another example of a lock ring retainer. [Figure 21] FIG. 13 is a front view of another example of a lock ring retainer. [Figure 22] FIG. [Figure 23] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, one embodiment of the present invention will be described. 1, the pipe joint 11 includes two cylindrical joint bodies 12 to which resin pipes 51 are connected. Each joint body 12 is made of a synthetic resin such as polyphenylene sulfide resin. The resin pipes 51 are made of a synthetic resin such as polyolefin (crosslinked polyethylene, polybutene, etc.).

[0011] One joint body 12 and the other joint body 12 are arranged so as to face in opposite directions at 180 degrees on the same axis. One joint body 12 and the other joint body 12 have the same structure, and one joint body 12 and the other joint body 12 form one-touch joints of the same structure. Therefore, hereinafter, only one joint body 12 will be described, and a description of the other joint body 12 will be omitted.

[0012] An inner cylinder 14 and an outer cylinder 15 are formed on the joint body 12 so as to protrude from the inner and outer circumferences at a distance. The inner space of the inner cylinder 14 serves as a flow path 18 through which fluids such as water flow. An insertion space 13 into which a resin pipe 51 is inserted is formed between the inner cylinder 14 and the outer cylinder 15. A step 15a is provided on the base end side of the inner circumferential surface of the outer cylinder 15. A locking step 15b is provided on the tip side of the step 15a on the inner circumferential surface of the outer cylinder 15.

[0013] A seal ring holder 16 made of polyacetal resin is engaged with the engagement step 15b. A seal ring 17 made of rubber such as ethylene-propylene-diene copolymer rubber is disposed in the space between the seal ring holder 16 and the step 15a. When the resin pipe 51 is inserted into the insertion space 13, the seal ring 17 is crushed between the outer circumferential surface of the resin pipe 51 and the inner circumferential surface of the outer tube 15, thereby ensuring watertightness between the two circumferential surfaces.

[0014] The axial length of the contact area between the seal ring 17 and the plastic pipe 51 when the seal ring 17 is in the crushed state is defined as the "seal length S." The seal length S is approximately 2.2 mm for the pipe fitting 11 corresponding to the plastic pipe 51 with a nominal diameter of "10A," "13A," or "16A," approximately 2.5 mm for the pipe fitting 11 corresponding to the plastic pipe 51 with a nominal diameter of "20A," and approximately 2.65 mm for the pipe fitting 11 corresponding to the plastic pipe 51 with a nominal diameter of "25A."

[0015] The wire diameter of the seal ring 17 is 3.6 mm for pipe fittings 11 corresponding to plastic pipes 51 having a nominal diameter of "10A", "13A" or "16A", 4.1 mm for pipe fittings 11 corresponding to plastic pipes 51 having a nominal diameter of "20A", and 5 mm for pipe fittings 11 corresponding to plastic pipes 51 having a nominal diameter of "25A".

[0016] The pipe joint 11 includes a retaining mechanism 23 for holding the resin pipe 51 in the joint body 12, and a cap 20 for attaching the retaining mechanism 23 to the joint body 12. The cap 20 is made of a synthetic resin such as polyphenylene sulfide resin. Two locking grooves 21 are formed on the inner peripheral surface of the cap 20. Two locking protrusions 19 are formed on the outer peripheral surface of the outer tubular portion 15. The cap 20 is fitted onto the outer tubular portion 15, and is connected to the outer tubular portion 15 by engaging the locking grooves 21 with the locking protrusions 19 of the outer tubular portion 15. The cap 20 has an inclined surface 22 on the inner peripheral surface of the tip portion, the diameter of which decreases toward the tip side.

[0017] The lock ring 24 constituting the retaining mechanism 23 is made of a thin metal plate such as stainless steel and has an annular shape. A plurality of retaining pieces 24a are formed on the inner periphery of the lock ring 24 so as to protrude and incline toward the inner end. A split ring 26 constituting the retaining mechanism 23 is interposed between the lock ring 24 and the cap 20. The split ring 26 is made of a synthetic resin such as polyphenylene sulfide resin. The split ring 26 backs up and maintains the inclination angle of the retaining pieces 24a of the lock ring 24.

[0018] A lock ring holder 25 constituting the retaining mechanism 23 is sandwiched between the seal ring holder 16 and the cap 20. A lock ring 24 is sandwiched between the lock ring holder 25 and the split ring 26. Assume that a pulling force is applied to the plastic pipe 51 inserted into the insertion space 13 and having the split ring 26 and lock ring 24 inserted therethrough. In this case, the retaining pieces 24a of the lock ring 24 bite into the outer circumferential surface of the plastic pipe 51, thereby preventing the plastic pipe 51 from coming off from the pipe fitting 11. Also, in this case, the split ring 26 is guided by the inclined surface 22 of the cap 20 to reduce its diameter and tighten the outer circumferential surface of the plastic pipe 51, thereby preventing the plastic pipe 51 from coming off from the pipe fitting 11.

[0019] An insertion guide 29 made of synthetic resin such as polypropylene resin is disposed in the insertion space 13. The insertion guide 29 is pressed by the tip of the resin pipe 51 and moves ahead of the resin pipe 51. Therefore, the insertion guide 29 allows the tip of the resin pipe 51 to smoothly pass through each of the split ring 26, the lock ring 24, and the seal ring 17.

[0020] An attachment groove 20a is formed annularly in the circumferential direction on the outer peripheral surface of the cap 20. A cylindrical tightening cover 30 is engaged with the attachment groove 20a of the cap 20. The tightening cover 30 is made of a metal such as stainless steel, and tightens the cap 20 to make it difficult to expand in diameter, thereby preventing the cap 20 from coming off the fitting body 12.

[0021] Next, the lock ring holder 25 will be described. The lock ring holder 25 is made of synthetic resin such as acetal resin and has a circular shape. The lock ring holder 25 determines the position (centering) of the lock ring 24.

[0022] A plurality of positioning protrusions 25a are formed on the outer periphery of the front and back surfaces of the lock ring holder 25. The positioning protrusions 25a are provided on the front and back surfaces of the lock ring holder 25 in order to eliminate front-back directionality when the lock ring holder 25 is assembled to the cap 20. The lock ring 24 is disposed in a space surrounded by the plurality of positioning protrusions 25a on one of the front and back sides of the lock ring holder 25. The lock ring holder 25 centers the lock ring 24 by abutting against the positioning protrusions 25a to restrict the relative movement of the lock ring 24 in the radial direction. The length of each positioning protrusion 25a in the axial direction is approximately the same as the plate thickness of the lock ring 24, which is approximately 0.5 mm.

[0023] Lock ring holder 25-16A shown in Figures 4 to 9 is for pipe fitting 11 compatible with resin pipe 51 with a nominal diameter of "16A". The outer peripheral surface of lock ring holder 25-16A is formed with crushed margins 25b for use when press-fitting and fixing into cap 20. The outer peripheral side of each positioning protrusion 25a of lock ring holder 25-16A forms a convex curved surface that smoothly connects to the outer peripheral surface of lock ring holder 25-16A.

[0024] The positioning protrusions 25a extend a length X along the circumferential direction of the lock ring retainer 25-16A, and ten of them are arranged on each of the front and back sides at a predetermined interval Y (7.78 mm in this embodiment) around the circumferential direction of the lock ring retainer 25-16A.

[0025] In the lock ring holder 25-16A, the length X of each positioning protrusion 25a is set to be equal to or less than the seal length S (see FIG. 1, approximately 2.2 mm) between the seal ring 17 and the resin pipe 51, for example, 2 mm to 2.2 mm.

[0026] In the lock ring retainer 25-16A, the length X of each positioning protrusion 25a is set to be smaller than the predetermined interval Y between the positioning protrusions 25a. The group of positioning protrusions 25a on the front side and the group of positioning protrusions 25a on the back side are arranged with a phase shift in the circumferential direction so that they do not all overlap when viewed in the axial direction (see especially Figures 4 and 5). In this way, the axial thickness of the lock ring retainer 25-16A can be prevented from becoming excessively large at the positioning protrusions 25a. Therefore, for example, during injection molding of the lock ring retainer 25-16A, the flow of resin material in the circumferential direction can be made smooth, and molding defects (for example, sink marks) can be prevented.

[0027] Next, the differences between the lock ring holder 25-10A, 25-13A, 25-20A, and 25-25A of the pipe fitting 11 corresponding to the plastic pipes 51 with nominal diameters of "10A", "13A", "20A", and "25A" from the lock ring holder 25-16A described above will be explained. Naturally, the inner and outer diameters of the lock ring holder 25 increase in the order of 25-10A, 25-13A, 25-16A, 25-20A, and 25-25A.

[0028] As shown in Fig. 10, the lock ring retainer 25-10A has eight positioning protrusions 25a on each of the front and back surfaces. The length X of each positioning protrusion 25a is set to be equal to or less than the seal length S (see Fig. 1, approximately 2.2 mm) between the seal ring 17 and the resin pipe 51, and is set to, for example, 2 mm to 2.2 mm. The predetermined interval Y between the multiple positioning protrusions 25a is 6.31 mm.

[0029] As shown in Fig. 11, the lock ring retainer 25-13A has eight positioning protrusions 25a on each of the front and back surfaces. The length X of each positioning protrusion 25a is set to be equal to or less than the seal length S (see Fig. 1, approximately 2.2 mm) between the seal ring 17 and the resin pipe 51, and is set to, for example, 2 mm to 2.2 mm. The predetermined interval Y between the multiple positioning protrusions 25a is 7.88 mm.

[0030] As shown in Fig. 12, the lock ring retainer 25-20A has twelve positioning protrusions 25a on each of the front and back surfaces. The length X of each positioning protrusion 25a is set to be smaller than the seal length S (see Fig. 1, approximately 2.5 mm) between the seal ring 17 and the resin pipe 51, and is set to, for example, 2.3 mm to 2.5 mm. The predetermined interval Y between the multiple positioning protrusions 25a is 7.22 mm.

[0031] As shown in Fig. 13, the lock ring holder 25-25A has twelve positioning protrusions 25a on each of the front and back faces. The length X of each positioning protrusion 25a is set to be smaller than the seal length S (see Fig. 1, approximately 2.65 mm) between the seal ring 17 and the resin pipe 51, and is set to, for example, 2.45 mm to 2.65 mm. The predetermined interval Y between the multiple positioning protrusions 25a is 8.01 mm.

[0032] Next, the assembly of the pipe joint 11 will be described. 2 shows the state before the cap 20 is assembled to the joint body 12. In this state, a seal ring 17 is disposed in the insertion space 13 of the joint body 12, and a seal ring holder 16 is press-fitted into the outer tubular portion 15, so that the seal ring 17 is prevented from coming out by the seal ring holder 16. In addition, in the cap 20, a lock ring 24 and a split ring 26 are disposed on the inside, and a lock ring holder 25 is press-fitted into the inner circumferential surface of the cap 20, so that the lock ring 24 and the split ring 26 are prevented from coming out by the lock ring holder 25.

[0033] The sub-assembly consisting of the joint body 12, seal ring holder 16, seal ring 17, and insertion guide 29, and the sub-assembly consisting of the cap 20, lock ring 24, lock ring holder 25, and split ring 26 are integrated through a pressing process. In this pressing process, the joint body 12 is pressed into the cap 20, so that the cap 20 is snap-engaged with the outer tube portion 15 of the joint body 12. After this pressing process, a tightening cover 30 (see FIG. 1) is attached to the cap 20.

[0034] Here, in the pressing process, the inner diameter of the cap 20 temporarily expands during the process in which the cap 20 is snap-engaged with the fitting body 12. Therefore, relative movement between the lock ring 24 and the lock ring retainer 25 in the radial and axial directions is likely to occur.

[0035] 3, if the cap 20 is pressed strongly against the fitting body 12 when there is radial and axial misalignment between the lock ring 24 and the lock ring holder 25, the lock ring 24 may scrape off the positioning protrusion 25a of the lock ring holder 25, particularly the tip inner edge 25a-1. Fragments of the scraped-off positioning protrusion 25a may get in between the plastic pipe 51 and the seal ring 17 when the plastic pipe 51 is inserted into the pipe fitting 11.

[0036] However, in the lock ring retainer 25 of this embodiment, the length X of each positioning protrusion 25a is set to be less than or equal to the seal length S between the seal ring 17 and the plastic pipe 51. Therefore, even if, for example, the tip inner edge 25a-1 of the positioning protrusion 25a is scraped off by the length X in the circumferential direction by the lock ring 24 and the resulting fragments get into, for example, between the seal ring 17 and the plastic pipe 51, no water passage will be opened in the axial direction of the seal ring 17 at the portion where the fragments get in, and therefore it is possible to prevent the watertightness of the pipe joint 11 from decreasing.

[0037] In addition, when the length X of the positioning protrusion 25a is the same as the seal length S between the seal ring 17 and the resin pipe 51, theoretically, if a fragment of the positioning protrusion 25a of length X fits exactly into the range that defines the seal length S, there is a high possibility that a water passage will open at the part where the fragment fits in. However, since the possibility that the positioning protrusion 25a is scraped off at length X is low, and the possibility that the fragment fits exactly into the range that defines the seal length S is even lower, it can be said that there is no problem in practical use. In that sense, the length X of the positioning protrusion 25a may be 1.5 times or less the seal length S between the seal ring 17 and the resin pipe 51.

[0038] Furthermore, if the length X of the positioning protrusion 25a is small, the fragments of the positioning protrusion 25a tend to be small, so that deterioration of watertightness caused by the fragments can be more effectively prevented. However, if the length X of the positioning protrusion 25a is too small, the durability of the positioning protrusion 25a decreases, and the positioning protrusion 25a becomes more likely to be scraped off by the lock ring 24. In consideration of these factors, the length X of the positioning protrusion 25a is preferably 0.9 times or more the seal length S between the seal ring 17 and the resin pipe 51.

[0039] (Another example) The above embodiment can be modified, for example, as follows. As shown in Figures 14 to 19, the three positioning protrusions 25a are arranged consecutively in the circumferential direction. In this case, the tip inner edge 25a-1 of each of the three positioning protrusions 25a is not made consecutive in the circumferential direction to the tip inner edge 25a-1 of the adjacent positioning protrusion 25a.

[0040] By doing so, for the entire three positioning projections 25a, the circumferential length (= X + X + X) is set to be significantly more than 1.5 times the seal length S (see Fig. 1), so that the locking ring 24 (see Fig. 1) can be stably centered. In particular, the length X' (< X) of the inner edge 25a-1 of the tip of each positioning projection 25a that is particularly easily shaved off is set to be 1.5 times or less the seal length S, thereby also preventing the reduction in watertightness as described above.

[0041] Note that the number of positioning projections 25a continuous in the circumferential direction may be a plurality other than three. For example, it may be two as shown in Fig. 20, or four as shown in Fig. 21, or may be five, six, seven, eight, nine, or ten.

[0042] ○ As shown in Figs. 14 to 21, regarding the predetermined interval Y in the circumferential direction between adjacent and non - continuous positioning projections 25a, it is set to be less than the length obtained by dividing the circumferential length of the outer periphery of the locking ring 24 (see Fig. 1) by the number of retaining pieces 24a that the locking ring 24 has. By doing so, for example, when the locking ring 24 breaks in the radial direction and each retaining piece 24a becomes a single fragment, the circumferential length of the outer peripheral edge of the fragment will exceed the predetermined interval Y. Therefore, it is possible to prevent the fragment from slipping out radially outward from the predetermined interval Y, and the fragment can be held inside the positioning projection 25a of the locking ring retainer 25 (25 - 16A). As a result, the function of the retaining piece 24a can be maintained, and the slipping out of the resin pipe 51 (see Fig. 1) can be suppressed.

[0043] ○ Although the pipe joint 11 is a so - called outer - diameter seal joint, it may be embodied in an inner - diameter seal joint. ○ Arrange the group of front - side positioning projections 25a and the group of back - side positioning projections 25a such that some or all of the corresponding positioning projections 25a overlap when viewed in the axial direction.

[0044] The pipe fitting 11 was constructed by integrating two sub-assemblies in a pressing process (see Figure 2). This can be changed to a configuration in which, for example, the seal ring 17, seal ring holder 16, lock ring holder 25, lock ring 24, and split ring 26 are assembled to the fitting body 12 in the same order, and then the cap 20 alone is assembled to the fitting body 12. In this case, since there is no need to hold the lock ring 24 and split ring 26 in the cap 20 alone, the lock ring holder 25 can be deleted, and by forming a portion similar to the positioning protrusion 25a on the seal ring holder 16, the seal ring holder 16 can also serve as the "lock ring holder."

[0045] (Additional Note) The technical ideas that can be understood from the above embodiment will be described. (1) A pipe fitting equipped with an anti-slip mechanism for holding a plastic pipe to a fitting body, and a seal ring for ensuring watertightness between the fitting body and the plastic pipe, wherein the anti-slip mechanism is a pipe fitting equipped with a metal lock ring and a lock ring holder made of synthetic resin in which the lock ring is positioned in a space surrounded by a plurality of positioning protrusions formed on the outer periphery to center the lock ring, and wherein the circumferential length of the positioning protrusions on the lock ring holder is set to 1.5 times or less the seal length in the axial direction between the seal ring and the plastic pipe.

[0046] (2) A pipe fitting comprising an anti-slip mechanism for holding a plastic pipe to a fitting body, a synthetic resin cap for attaching the anti-slip mechanism to the fitting body, and a seal ring for ensuring watertightness between the fitting body and the plastic pipe, wherein the anti-slip mechanism comprises a metal lock ring and a synthetic resin lock ring holder in which the lock ring is positioned in a space surrounded by a plurality of positioning protrusions formed on the outer periphery for centering the lock ring, and the cap is fitted onto the fitting body by snap engagement, and the circumferential length of the positioning protrusions of the lock ring holder is set to be less than the axial seal length between the seal ring and the plastic pipe.

[0047] (3) A pipe fitting according to technical idea (1) or (2), wherein the circumferential length of the positioning protrusion is 0.9 times or more the seal length between the seal ring and the plastic pipe.

[0048] (4) A pipe fitting according to any one of technical ideas (1) to (3), wherein the lock ring retainer has a plurality of positioning protrusions formed on the outer periphery of each of its front and rear surfaces, the lock ring is disposed in a space surrounded by the plurality of positioning protrusions on one of the front and rear surfaces, and the group of positioning protrusions on the front surface and the group of positioning protrusions on the rear surface are shifted in phase in the circumferential direction so as not to overlap when viewed in the axial direction.

[0049] (5) A pipe fitting comprising an anti-slip mechanism for holding a plastic pipe to a fitting body, a synthetic resin cap for attaching the anti-slip mechanism to the fitting body, and a seal ring for ensuring watertightness between the fitting body and the plastic pipe, wherein the anti-slip mechanism comprises a metal lock ring and a synthetic resin lock ring holder for centering the lock ring by positioning the lock ring in a space surrounded by a plurality of positioning protrusions formed on the outer periphery, and the cap is fitted onto the fitting body by snap engagement, and the circumferential length of the inner edge of the tip of the positioning protrusions of the lock ring holder is set to be less than the axial seal length between the seal ring and the plastic pipe.

[0050] (6) A pipe fitting equipped with an anti-slip mechanism for holding a plastic pipe to a fitting body, and a seal ring for ensuring watertightness between the fitting body and the plastic pipe, wherein the anti-slip mechanism is a pipe fitting equipped with a metal lock ring and a lock ring holder made of synthetic resin in which the lock ring is positioned in a space surrounded by a plurality of positioning protrusions formed on the outer periphery for centering the lock ring, and wherein the circumferential length of the inner edge of the tip of the positioning protrusions on the lock ring holder is set to 1.5 times or less the seal length in the axial direction between the seal ring and the plastic pipe. [Explanation of symbols]

[0051] 11...pipe joint, 12...joint body, 17...seal ring, 20...cap, 23...anti-slip mechanism, 24...lock ring, 25...lock ring holder, 25a...positioning protrusion, 51...plastic pipe.

Claims

[Claim 1] A pipe joint having a slip-out prevention mechanism for holding a plastic pipe to a joint body, and a seal ring for ensuring watertightness between the joint body and the plastic pipe, wherein the slip-out prevention mechanism is a metal lock ring and a synthetic resin lock ring retainer for centering the lock ring by arranging the lock ring in a space surrounded by a plurality of positioning protrusions formed on an outer periphery of the metal lock ring; The positioning protrusions are arranged at predetermined intervals in the circumferential direction of the lock ring retainer, A pipe fitting in which a circumferential length of an inner edge of a tip of the positioning protrusion on the lock ring holder is set to be smaller than the predetermined interval.

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