JP2020165535A - Pipe joint and pipe joint structure - Google Patents

Abstract

To reduce a risk that an excessive load is applied on a loose flange while securing seal performance, in a pipe joint including a resin-made stub end and the resin-made loose flange.SOLUTION: A pipe joint 13 is arranged at an end part 12 of a pipe 10, and joined to a joining mating pipe 20. A resin-made loose flange 40 is fit into an external periphery of a resin-made stub end 30 of the pipe joint 13. An annular recess 42 is formed at a center hole 41 of the loose flange 40, and a flare part 32 of the stub end 30 is accepted into the annular recess 42. In a state that a step face 42d of the annular recess 42 abuts on a back face 32d of the flare part 32, a stub face 30a oriented to the mating pipe 20 of the stub end 30 is not flush with respect to a flange face 40a of the loose flange 40 within a prescribed irregular range progressing along a pipe axis L. An upper limit of the irregular rotation number at a recessive side is 0.5 mm, and an upper limit at a protrusive side is 5.0 mm.SELECTED DRAWING: Figure 4

Description

The present invention relates to a pipe joint and a pipe joint structure, and particularly to a pipe joint and a pipe joint structure having a loose flange.

Generally, flanges for joining with other pipes are provided at the ends of various pipes such as factory pipes. The flanges of the two pipes are connected by bolts or the like. At this time, where it is necessary to match the bolt holes of these flanges, it is not easy to adjust the angle of the flange by turning the entire pipe. Therefore, as the flange of at least one of the pipes, a loose flange rotatably loosely fitted to the outer periphery of the pipe end (stub end) is used (see Patent Document 1 and the like).

The loose flange of Patent Document 1 is formed in the shape of a flat annular plate. The loose flange is abutted against the back surface of the flange-shaped flare portion of the star end (the surface facing the side opposite to the joining partner). Therefore, the front surface of the loose flange (flange surface facing the joint mating side) is arranged so as to recede from the front surface of the stub end (stub surface facing the joint mating side) by the thickness of the flare portion.

Most of the conventional factory piping was made of metal, and many of the fittings including stub ends and loose flanges were also made of metal. On the other hand, due to recent advances in resin synthesis technology, the mechanical strength, weather resistance, chemical resistance, earthquake resistance, etc. of resins have been improved, and the factory piping has changed from metal pipes to resin pipes such as polyvinyl chloride and polyethylene. Is being replaced by. In response to this, resin pipe fittings are desired.
Patent Document 2 discloses that a short resin pipe with a flange is joined to an end portion of the resin pipe.

Japanese Patent Application Laid-Open No. 5-280674 Japanese Unexamined Patent Publication No. 2001-205707

When the stub end and loose flange are made of resin, a certain thickness is required to secure the required strength. The flared portion also needs to have a certain thickness. However, in a pipe joint structure as in Patent Document 1, for example, if the flare portion is made thicker, the loose flange is arranged so as to be largely retracted from the front surface (stub surface) of the stub end. For this reason, the gap between the loose flange and the flange of the joining partner is too large, and depending on the tightening torque when joining these flanges with bolts, the resin loose flange is greatly deformed and an excessive stress load is applied. There is a risk of being damaged. On the other hand, if the tightening torque is made too small, the seal between the pipes cannot be secured.
In view of such circumstances, an object of the present invention is to reduce the risk of an excessive load being applied to the loose flange in a pipe joint including a resin stub end and a resin loose flange while ensuring sealing performance. To do.

In order to solve the above-mentioned problems, the present invention is a pipe joint provided at the pipe end portion of one pipe and joined to a joint partner.
A stub end made of resin, including a tubular pipe insertion portion into which the pipe end portion is inserted, and an annular flare portion provided so as to project from the end portion of the pipe insertion portion on the joining partner side to the outer peripheral side. When,
A loose flange made of an annular resin having an annular recess formed in a portion of the center hole through which the stub end is passed, which is open to the junction partner side and the inner peripheral side to receive the flare portion.
The stub surface facing the joining partner side at the stub end is loose, with the stepped surface facing the joining partner side in the annular recess being abutted against the back surface facing the pipe insertion portion side in the flare portion. It is non-facial within a predetermined uneven range along the pipe axis with respect to the flange surface of the flange facing the joint mating side.
The upper limit of the concave side of the uneven range is 0.5 mm, and the upper limit of the convex side is 5.0 mm.

According to the pipe joint, even if the flare portion of the resin stub end is thick, the flare portion is accommodated in the annular recess of the loose flange to join the flange surface of the loose flange to the back surface of the flare portion. Can be placed forward to the other side. Therefore, it is possible to prevent the gap between the loose flange and the flange of the joining partner from becoming excessive, and it is possible to reduce the risk that an excessive load is applied to the loose flange made of resin.
If the stub surface is set so as to be recessed with respect to the flange surface, the flange surface can be brought into contact with the flange of the joining partner directly or via packing, and deformation of the loose flange can be reliably prevented. By setting the upper limit (0.5 mm) on the concave side, the sealing property is ensured.
If the stub surface is set to be convex with respect to the flange surface, the stub surface can be reliably brought into close contact with the packing, and sufficient sealing performance can be ensured. By setting the upper limit (5.0 mm) on the convex side, it is possible to prevent the loose flange from being deformed excessively and to prevent the load from becoming excessive.

The pipe joint structure according to the present invention includes a pipe joint including the stub end and a loose flange, an annular packing arranged between the pipe joint and the flange of the joint partner, and the loose flange, the packing and the joint partner. Equipped with bolts that penetrate and join the flange
An annular convex portion facing the stub surface is formed in a portion of the packing between the bolt hole through which the bolt is passed and the center hole.
The protruding height of the annular convex portion is larger than 0.5 mm.

In the pipe joint structure, even when the stub surface is recessed with respect to the flange surface, the recess is 0.5 mm at the maximum, which is smaller than the protruding height (more than 0.5 mm) of the annular convex portion. Therefore, the stub surface is surely in contact with the annular convex portion, and the sealing property can be ensured.
By adjusting the amount of unevenness on the stub surface and flange surface, the compressive force applied to the packing can be adjusted, damage and deterioration of the packing can be suppressed, and the sealing performance can be improved.
By passing the bolt through the packing, the position of the packing can be prevented from shifting.
By making the outer diameter of the packing the same as that of the loose flange, it is possible to easily visually confirm whether or not the packing is sandwiched between the pipe joints.

According to the present invention, it is possible to reduce the risk of an excessive load being applied to the loose flange while ensuring the sealing property of the pipe joint including the resin stub end and the resin loose flange.

FIG. 1 shows a pipe joint structure according to an embodiment of the present invention in an assembled state, and FIG. 1A is a side sectional view of a mode in which a stub surface is recessed with respect to a flange surface. .. FIG. (B) is a side sectional view of a mode in which the stub surface projects with respect to the flange surface. FIG. 2A is an exploded cross-sectional view of the pipe joint structure in the recessed mode. FIG. (B) is an exploded cross-sectional view of the pipe joint structure in the protruding mode. FIG. 3A is a plan view of the stub end of one pipe joint in the pipe joint structure. FIG. 3B is a side view of the stub end. FIG. 4A is an enlarged cross-sectional view showing a part of the pipe joint in the recessed mode. FIG. 4B is an enlarged cross-sectional view showing a part of the pipe joint in the protruding mode. FIG. 5A is a front view of the loose flange of the pipe joint. FIG. 5B is a rear view of the loose flange. FIG. 6A is a cross-sectional view taken along the line VIa-VIa of FIG. 5A. FIG. 6B is a cross-sectional view taken along the line VIb-VIb of FIG. 5A. FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 5 (b). FIG. 8 is a front view of the packing of the pipe joint structure.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1 (a) and 1 (b) show a joining structure of the pipe 10 of 1 and the mating pipe 20 (joining partner) in the factory piping. In the following description, unless otherwise specified, the pipes 10 and 20 are assumed to be in a joined state.
The materials of the tubes 10 and 20 are, for example, polyvinyl chloride (PVC), polyolefin (polyethylene (PE), polypropylene (PP), etc.) and other resins.
The materials of the two tubes 10 and 20 are preferably the same, but may be different from each other.

As shown in FIGS. 1 and 2, two pipes 10 and 20 are arranged side by side on the pipe shaft L via the pipe joint structure 1 and are joined by the pipe joint structure 1. The pipe joint structure 1 includes pipe joints 13 and 23, bolts 60 and nuts 61, and packing 50. Pipe joints 13 and 23 are provided at opposite ends 12 and 22 of the pipes 10 and 20. These pipe joints 13 and 23 are abutted against each other with the packing 50 interposed therebetween, and the flanges 40 and 24 of the pipe joints 13 and 23 are connected to each other by a fastener composed of a bolt 60 and a nut 61.

As shown in FIGS. 2 (a) and 2 (b), the pipe joint 13 provided in the pipe 10 of 1 includes a tubular stub end 30 and an annular loose flange 40.
The material of the stub end 30 is, for example, polyvinyl chloride (PVC), polyolefin (polyethylene (PE), polypropylene (PP), etc.) or other resin, and is the same as the pipe 10 in consideration of adhesiveness to the pipe 10. It is preferably made of a material. When the tube 10 is made of PVC, the material of the stub end 30 is preferably PVC. Further, the stub end 30 may be a fiber reinforced resin containing reinforcing fibers such as glass fiber and carbon fiber.

As shown in FIGS. 3 (a) and 3 (b), the stub end 30 integrally has a pipe insertion portion 31 and a flare portion 32. The pipe insertion portion 31 is formed in a tubular shape having an insertion hole 33 along the pipe shaft L. The rear end 33e of the insertion hole 33 is opened to the rear end surface 30e (the surface facing the side opposite to the joining partner side) of the stub end 30. The front end 33f of the insertion hole 33 is opened on the front surface of the stub end 30, that is, the stub surface 30a facing the joint mating side.

As shown in FIGS. 2A and 2B, at least the inner peripheral surface 33a of the insertion hole 33 before the pipe 10 is inserted shrinks from the rear end opening 33e toward the front (joining partner side). It is a tapered surface with a diameter. As shown in FIGS. 1A and 1B, the end portion 12 of the pipe 10 is inserted (press-fitted) into the insertion hole 33 through the opening 33e, so that the inner peripheral surface 33a is inserted into the pipe end portion 12. It is deformed to imitate, and the pipe insertion portion 31 is slightly bulged as compared with the case where the pipe end portion 12 is not inserted.
Although not shown, a resin adhesive is interposed between the inner peripheral surface 33a of the pipe insertion portion 31 and the outer peripheral surface of the pipe end portion 12. The stub end 30 and the pipe 10 are adhered to each other by the adhesive.

As shown in FIGS. 3 (a) and 3 (b), a shallow rectangular groove 36 having a rectangular wave pattern and a retaining protrusion 35 are formed on the outer peripheral surface 31a of the pipe insertion portion 31. .. The retaining protrusion 35 has a semicircular cross section and extends along the pipe axis L. The rear end portion 35e of the retaining protrusion 35 has a hemispherical shape. The front end surface 35d of the retaining protrusion 35 facing the flare portion 32 is substantially orthogonal to the pipe axis L.

As shown in FIGS. 2 (a) and 2 (b), an annular inner flange portion 34 projects radially inward on the inner circumference of the front end portion (end portion on the joint mating side) of the stub end 30. Is formed in. The opening 33f is defined by the inner peripheral edge of the inner flange portion 34.

As shown in FIGS. 2A and 2B, a flare portion 32 is provided on the outer periphery of the front end portion of the stub end 30. The flare portion 32 is formed in an annular shape having a larger diameter and a thicker wall than the pipe insertion portion 31, and protrudes from the pipe insertion portion 31 toward the outer peripheral side.

As shown in FIGS. 4A and 4B, the stub entrance corner 31c formed by the back surface 32d of the flare portion 32 facing the pipe insertion portion side and the outer peripheral surface 31a of the pipe insertion portion 31 is preferably formed. It is an R surface with a relatively large radius of curvature of about several mm.
The stub protruding corner 32c formed by the outer peripheral surface 32a and the back surface 32d in the flare portion 32 is preferably an R surface having a relatively large radius of curvature of about several mm.
The radii of curvature of the corners 31c and 32c are preferably equal to each other, but may be different from each other.

As shown in FIGS. 2A and 2B, a loose flange 40 is provided on the outer periphery of the stub end 30.
The material of the loose flange 40 is preferably a resin having high resistance to bolt tightening, internal pressure, thermal stress, etc., and examples thereof include thermoplastic resins of polyvinyl chloride and polyolefin (polyethylene (PE), polypropylene (PP), etc.). .. The resin constituting the loose flange 40 preferably contains reinforcing fibers such as glass fiber and carbon fiber in order to increase the rigidity and suppress cracking at the time of joining or the like.

As shown in FIGS. 5A and 5B, the loose flange 40 is formed in the shape of a ring plate having a diameter larger than that of the flare portion 32. The outer diameter of the loose flange 40 is determined by the JIS standard according to the diameter of the pipe 10.
An annular recess 42 is formed in the front side portion (the portion on the joining partner side) of the center hole 41 of the loose flange 40. The annular recess 42 is open to the front (joining partner side) and the inner peripheral side. Therefore, the inner peripheral surface of the center hole 41 has a small-diameter inner peripheral surface 41a, a large-diameter inner peripheral surface 42a, and a stepped surface 42d. The small-diameter inner peripheral surface 41a is arranged behind the annular recess 42 (on the side opposite to the joint mating side).
A relief recess 41g having a semicircular cross section corresponding to the retaining protrusion 35 is formed at one position in the circumferential direction of the small diameter inner peripheral surface 41a.

The large-diameter inner peripheral surface 42a has a larger diameter than the small-diameter inner peripheral surface 41a. The stepped surface 42d intersects the pipe axis L and is directed forward (joining partner side). The inner surface of the annular recess 42 is defined by the large-diameter inner peripheral surface 42a and the stepped surface 42d.

As shown in FIGS. 4A and 4B, the flange entrance corner 42c formed by the large-diameter inner peripheral surface 42a and the stepped surface 42d of the loose flange 40 preferably has a relatively large curvature of about several mm. It is an R surface with a radius.
The flange protruding corner corner 41c formed by the stepped surface 42d and the small diameter inner peripheral surface 41a is preferably an R surface having a relatively large radius of curvature of about several mm.
The radii of curvature of the corners 41c and 42c are preferably equal to each other, but may be different from each other. Further, the radii of curvature of the corners 41c and 42c are equal to the radii of curvature of the corners 31c and 32c of the stub end 30, but may be different from each other.

As shown in FIGS. 5 (a) and 5 (b), a plurality of (for example, eight) bolt holes 43 are formed in the loose flange 40. These bolt holes 43 are spaced apart from each other in the circumferential direction of the loose flange 40, and are preferably arranged at equal intervals. Each bolt hole 43 penetrates from the front surface of the loose flange 40, that is, the flange surface 40a facing the joint mating side to the back surface 40b on the opposite side in the thickness direction (pipe axis direction).
As shown in FIGS. 1 and 2, the loose flange 40 faces the flange 24 of the pipe joint 23 provided at the end of the mating pipe 20 (joining mating), and each bolt hole 43 is a bolt hole of the flange 24. It is aligned with 25. Bolts 60 are passed through these bolt holes 43 and 25 and tightened with nuts 61. As a result, the pipe joints 13 and 23 are bolted together, and the pipes 10 and 20 are joined together.

As shown in FIGS. 5 (b), 6 (a), and 7, a plurality of (for example, four) ribs 44 are formed on the back surface 40b of the loose flange 40. The ribs 44 are spaced apart from each other in the circumferential direction of the loose flange 40, and are preferably arranged at equal intervals (90 ° intervals). Each rib 44 projects from the back surface 40b and extends in the radial direction of the loose flange 40. Preferably, both ends of the rib 44 reach the outer and inner edges of the loose flange 40.
The arrangement angles of the rib 44 and the bolt hole 43 on the loose flange 40 are deviated from each other. Two bolt holes 43 are arranged between the two ribs 44 90 ° apart.
The rib 44 may be omitted.

As shown in FIGS. 5 (b) and 6 (b), a plurality of lightening recesses 45 are further formed on the back surface 40b of the loose flange 40 at intervals in the circumferential direction. Each lightening recess 45 is arranged between two adjacent bolt holes 43. The arrangement angle of some of the lightening recesses 45 overlaps with the arrangement angle of the rib 44. The part of the lightening recess 45 is divided into two by ribs 44.
The weight of the loose flange 40 is reduced by the lightening recess 45.
The lightening recess 45 may be omitted.

As shown in FIGS. 2A and 2B, the loose flange 40 is loosely fitted on the outer periphery of the stub end 30. In the non-joined state of the pipes 10 and 20, the loose flange 40 is movable and rotatable in the pipe axial direction with respect to the stub end 30. The retaining protrusion 35 restricts the movement of the loose flange 40 toward the rear end surface 30e. The movement of the loose flange 40 to the joint mating side is restricted by the contact between the stepped surface 42d and the back surface 32d of the flare portion 32.

The stub end 30 is passed through the center hole 41 of the loose flange 40. The small diameter inner peripheral surface 41a of the loose flange 40 surrounds the pipe insertion portion 31.
The flare portion 32 is received in the annular recess 42. The large-diameter inner peripheral surface 42a surrounds the flare portion 32. The stepped surface 42d faces the back surface 32d of the flare portion 32.
The portion 40f of the loose flange 40 on the outer peripheral side (diameter outside) of the annular recess 42 is thicker than the flare portion 32.

As shown in FIGS. 4A and 4B, the stub surface 30a facing the joining partner side at the stub end 30 with the stepped surface 42d of the loose flange 40 abutting against the back surface 32d of the flare portion 32. Is set so as to be non-planetary within a predetermined uneven range along the pipe axis with respect to the flange surface 40a of the loose flange 40 facing the joining partner side.
The stub surface 30a may be non-planetary with respect to the flange surface 40a and may be recessed from the flange surface 40a (FIGS. 1 (a), 2 (a), 4 (a)), and the flange surface. It may be projected from 40a (FIG. 1 (b), FIG. 2 (b), FIG. 4 (b)).

The upper limit of the concave side of the uneven range of the stub surface 30a with respect to the flange surface 40a is 0.5 mm, and the upper limit of the convex side is 5.0 mm. That is, in FIG. 4A, the dent amount d1 of the stub surface 30a with respect to the flange surface 40a is 0.5 mm at the maximum.
In FIG. 4B, the protrusion amount d2 of the stub surface 30a with respect to the flange surface 40a is 5.0 mm at the maximum. The lower limit of the protrusion amount d2 is preferably 0.01 mm, more preferably 0.03 mm, further preferably 0.05 mm, and even more preferably 0.1 mm.

The stub surface 30a and the flange surface 40a are substantially parallel. It is preferable that the smoothness of the stub surface 30a and the accuracy of orthogonality with respect to the tube axis L are sufficiently high. The smoothness and orthogonality accuracy of the flange surface 40a may be lower than that of the stub surface 30a.
The flange surface 40a in the pipe joint 13 that is not joined to the mating pipe 20 may be slightly inclined with respect to the pipe shaft L depending on the degree of loose fitting of the loose flange 40.

As shown in FIGS. 2 (a) and 2 (b), a packing 50 is further arranged between the pipe joints 13 and 23 in the pipe joint structure 1.
The material of the packing 50 is preferably ethylene propylene diene (EPDM) rubber.

As shown in FIG. 8, the packing 50 is formed in an annular plate shape.
The outer diameter of the packing 50 is substantially the same as the outer diameter of the loose flange 40 and the flange 24. The inner diameter of the center hole 51 of the packing 50 is substantially the same as the inner diameter of the insertion hole 33.
A plurality of bolt holes 53 are arranged at intervals in the circumferential direction on the portion of the packing 50 facing the loose flange 40. These bolt holes 53 correspond to the bolt holes 43 and 25 of the flanges 40 and 24.
The bolt 60 passed through the bolt holes 43 and 25 is also passed through the bolt hole 53 of the packing 50.

Two large and small (plural) annular convex portions 54 and 55 are formed in the portions between the center hole 51 and the bolt hole 53 on both side surfaces of the packing 50. These annular convex portions 54 and 55 surround the central hole 51 and form a double circle concentric with the central hole 51.
The number of annular convex portions of the packing 50 is not limited to two, and may be three or more. Three or more annular convex portions having different diameters may be arranged so as to form multiple circles concentric with the central circle 51.

As shown in FIGS. 2A and 2B, the annular convex portions 54 and 55 of the packing 50 facing the pipe 10 side face the stub surface 30a.
The diameter of the smallest annular convex portion 54 is larger than the inner diameter of the stub surface 30a.
The diameter of the annular convex portion 55 having the maximum diameter is smaller than the outer diameter of the stub surface 30a.
The protruding height of the annular convex portions 54 and 55 is larger than the upper limit of the concave side of the uneven range, that is, 0.5 mm, preferably about 0.5 mm to 2 mm, and more preferably about 1 mm.
By tightening the bolt 60, the annular protrusions 54 and 55 are in close contact with the stub surface 30a over the entire circumference. As a result, the pipe joint 13 and the packing 50 are sealed.

The two pipes 10 and 20 are joined as follows.
First, the pipe joint 13 is assembled. That is, the loose flange 40 is fitted to the outer periphery of the pipe insertion portion 31 while the relief recessed groove 41g of the loose flange 40 and the retaining protrusion 35 of the stirrup 30 are angled, and the flare portion 32 is accommodated in the annular recess 42. After that, when the loose flange 40 is turned to shift the angle between the relief recessed groove 41g and the retaining protrusion 35, the loose flange 40 is prevented from coming off by the retaining protrusion 35.
The pipe end portion 12 is inserted into the insertion hole 33 of the pipe insertion portion 31 of the pipe joint 13. Preferably, an adhesive is applied in advance to the inner peripheral surface of the insertion hole 33 or the outer peripheral surface of the pipe end portion 12.

In this way, the pipe 10 to which the pipe joint 13 is attached and the mating pipe 20 to which the pipe joint 23 is separately attached are arranged in a row, and the pipe joints 13 and 23 face each other.
Subsequently, the angle of the loose flange 40 is adjusted so that the bolt hole 43 of the pipe joint 13 is aligned with the bolt hole 25 of the pipe joint 23. Since the loose flange 40 is rotatable, the bolt holes 43 and 25 can be easily aligned with each other.
A packing 50 is inserted between the pipe joints 13 and 23, and the bolt hole 53 of the packing 50 is aligned with the bolt holes 43 and 25.
Then, the bolt 60 is passed through the bolt holes 43, 53, 25 and tightened. As a result, the pipe joints 13 and 23 are joined to each other, and the pipes 10 and 20 are joined to each other.

According to the pipe joint 13, even if the flare portion 32 of the resin stub end 30 is thick, the end face 40a of the loose flange 40 is flared by accommodating the flare portion 32 in the annular recess 42 of the loose flange 40. It can be arranged so as to advance toward the joining partner side from the back surface 32d of the portion 32. Therefore, it is possible to avoid an excessive gap between the loose flange 40 and the flange 24 of the joining partner. Therefore, it is possible to reduce the risk that an excessive load is applied to the resin loose flange 40 due to bolt tightening or the like.
By making the loose flange 40 thicker, the rigidity can be increased and deformation can be suppressed.
By making the loose flange 40 made of a resin containing reinforcing fibers, the rigidity of the loose flange 40 can be further increased.
As a result, damage to the resin loose flange 40 can be reliably prevented.

As shown in FIGS. 1B and 4B, if the stub surface 30a is set to be convex with respect to the flange surface 40a, the packing 50 and the stub surface 30a can be reliably brought into close contact with each other. .. In particular, the annular convex portions 54 and 55 and the stub surface 30a can be strongly brought into close contact with each other to obtain a high sealing pressure. Thereby, the sealing property (sealing property) can be surely improved. By setting the upper limit (5.0 mm) on the convex side, it is possible to prevent the loose flange 40 from being excessively deformed, and it is possible to suppress the excessive load.

As shown in FIGS. 1 (a) and 4 (a), if the stub surface 30a is set to be recessed with respect to the flange surface 40a, the loose flange 40 is thrust through the flange 24 and the packing 50 of the joining partner. It can be applied, and it is possible to reliably avoid applying an excessive load to the loose flange 40. By setting the upper limit (0.5 mm) on the concave side, the sealing property is ensured. That is, even when the stub surface 30a is recessed with respect to the flange surface 40a, the recess is 0.5 mm at the maximum, which is larger than the protrusion height (more than 0.5 mm) of the annular convex portions 54 and 55 of the packing 50. small. Therefore, the stub end 30 is surely in contact with the annular protrusions 54 and 55, and the sealing property can be ensured. As a result, leakage of fluids such as water and chemicals passing through the pipes 10 and 20 can be reliably prevented.
By making the packing 50 larger in diameter than the flare portion 32, it can be easily visually confirmed from the outside whether or not the packing 50 is sandwiched between the flanges 40 and 24.
Since the bolt 60 penetrates the packing 50, it is possible to prevent the packing 50 from being displaced.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, by tightening the bolt, the loose flange 40 may be elastically deformed so as to bend toward the joint mating side, whereby the flange surface 40a may be brought into contact with the packing 40.
The pipes 10 and 20 are not limited to factory pipes, but may be civil engineering pipes, building pipes, or the like.
The stub end 30 may be formed integrally with the pipe 10.
The joining partner is a member provided with a flange to be joined to the loose flange 40, and examples thereof include a joint, a tank, and a pump in addition to the pipe 20.

The present invention can be applied to, for example, a joint of a factory pipe.

L pipe shaft 1 pipe joint structure 10 1 pipe 12 pipe end 13 pipe joint 20 mating pipe (joining partner)
30 Stub end 30a Stub surface (first joint surface)
31 Pipe insertion part 32 Flare part 32d Back side 33 Insertion hole 33a Inner peripheral surface 40 Loose flange 40a Flange surface (second joint surface)
40b Back surface 41 Center hole 42 Circular recess 42d Step surface 50 Packing 60 Bolt

Claims (2)

A pipe joint provided at the pipe end of the pipe 1 and joined to a joint partner.
A stub end made of resin, including a tubular pipe insertion portion into which the pipe end portion is inserted, and an annular flare portion provided so as to project from the end portion of the pipe insertion portion on the joining partner side to the outer peripheral side. When,
A loose flange made of an annular resin having an annular recess formed in a portion of the center hole through which the stub end is passed, which is open to the junction partner side and the inner peripheral side to receive the flare portion.
The stub surface facing the joining partner side at the stub end is loose, with the stepped surface facing the joining partner side in the annular recess being abutted against the back surface facing the pipe insertion portion side in the flare portion. It is non-facial within a predetermined uneven range along the pipe axis with respect to the flange surface of the flange facing the joint mating side.
A pipe joint characterized in that the upper limit of the concave side of the uneven range is 0.5 mm and the upper limit of the convex side is 5.0 mm. The pipe joint including the stub end and the loose flange according to claim 1, the annular packing arranged between the pipe joint and the flange of the joint partner, and the loose flange, the packing and the flange of the joint partner are penetrated. Equipped with bolts to join
An annular convex portion facing the stub surface is formed in a portion of the packing between the bolt hole through which the bolt is passed and the center hole.
A pipe joint structure characterized in that the protruding height of the annular convex portion is larger than 0.5 mm.

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