JP2014088933A - Fastening ring for connecting valve and pipe joint, powder coating method therefor, and valve and pipe joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fastening ring for connecting a valve and a pipe joint that can enhance corrosion resistance property while applying thin coating with powder coating to suppress its cost, and can ensure bond strength and sealability without damaging a resin pipe while maintaining the corrosion resistance property; a powder coating method of the fastening ring; and the valve and the pipe joint.SOLUTION: A transfer region 17 is a region that transfers from both end surfaces 16, 16 of an outer peripheral part 15 of a cylindrical ring body 10 to an inner peripheral part 18, and powder coating having a predetermined film thickness is applied to the outer peripheral part 15 and both end surfaces 16, 16. In the transfer region 17, a transfer coating film 31 is applied, which transfers from both end surfaces 16, 16 toward the inner peripheral part 18 so as to gradually become thin.

Description

  The present invention relates to a connection clamping ring used when connecting a soft synthetic resin pipe such as a polyethylene pipe for water supply to a valve or a fitting, and in particular, a clamping ring for connecting a valve or a fitting excellent in corrosion resistance. And its powder coating method, and valve and pipe joint.

  Conventionally, for example, in a soft seal gate valve for water supply, a connection socket is formed on the valve body, a synthetic resin pipe is fitted on the outer peripheral side of the connection socket, and the outer periphery of the synthetic resin pipe is tightened with a tightening ring. A synthetic resin pipe is connected. Thus, the joint structure which connects a synthetic resin pipe | tube using the ring for a fastening is utilized for the soft seal gate valve for water supply, various other valves, and pipe joints.

  As joint structures for pipe connection of valves and joints, for example, joints for resin pipes as disclosed in Patent Documents 1 to 3 are disclosed. These joints for resin pipes have a metal connection socket and a tightening ring. Insert the inner peripheral surface of the end of the soft synthetic resin tube into the connection socket, and insert the tightening ring into the outer periphery of the resin pipe. It is designed to connect tubes. At this time, by compressing the thickness of the resin tube with the connection socket and the tightening ring, the resin tube bites into the uneven portion of the connection socket, and a predetermined bonding strength is exerted. The tube is not easily pulled out. When the resin tube receives a force in the pulling direction, the stress is distributed and received by the uneven parts, so that local elongation does not occur, and the resin tube stretches as a whole and has the same drawability as the tube strength. Has to have.

  In the connection structure using such a connection socket and tightening ring, in the case of a valve, a connection socket as a connection portion is provided on the valve body side, and in the case of a pipe joint, the connection body becomes a connection socket. Resin pipes are connected to the sockets by fastening rings. These valves and pipe joints are required to have high durability because the connection socket is in contact with the fluid in the pipe and is often buried in the ground. Therefore, anti-corrosion treatment is applied to the connection socket and the tightening ring of the valve and pipe joint, respectively. In this case, the resin tube has a large dimensional tolerance in the thickness direction, unlike the metal tube. Therefore, it is necessary to keep the dimensional tolerance between the connection socket and the tightening ring small to ensure the bonding strength and sealing performance. There is.

For this reason, for example, a valve body having a connection socket is generally often subjected to powder coating in order to improve corrosion resistance. Powder coating is generally performed based on the standards of the Japan Water Works Association (soft seal gate valve for water supply: JWWA B120), and is provided with a certain film thickness with a predetermined dimensional accuracy.
On the other hand, the tightening ring also needs to have corrosion resistance equivalent to or better than that of the connection socket, and is subjected to anticorrosion treatment. In this case, since the thickness of the resin pipe varies greatly, it is necessary to control the compression width of the thickness of the resin pipe on the inner peripheral side of the fastening ring. For this reason, the tightening ring is usually subjected to a plating process in which the film thickness is thinner and the dimensional accuracy can be easily adjusted. When a resin tube is connected using a plated tightening ring, the plated portion of the inner periphery of the tightening ring contacts the outer periphery of the resin tube, and the powder coating portion of the outer periphery of the connection socket is applied to the inner periphery of the resin tube. The resin pipe is connected while contacting.

Japanese Patent Laid-Open No. 11-30377 Japanese Patent No. 3520187 Japanese Patent No. 3556115

  However, when the resin pipe is connected using a plated tightening ring, the plated portion is in contact with soil or the like, so that cracks and pinholes on the plated surface may lead to rust. For this reason, corrosion may occur due to long-term use, and it may become impossible to maintain the bonding strength and sealability. In the case of plating the tightening ring, there is a problem that costs are increased.

  Therefore, as an alternative to the plating treatment, it is also conceivable to apply powder coating to the entire inner peripheral surface of the fastening ring. However, in this case, it is difficult to adjust the thin film thickness, and it is difficult to maintain the dimensional accuracy in the thickness direction. In particular, it is difficult to adjust the film thickness of the concavo-convex portion that is a bite into the resin tube. In order to avoid powder coating on the uneven part, it is conceivable to mask this uneven part, and in this state, powder coating the inner peripheral surface with a certain thickness, but in this case the inner peripheral surface after painting As a result, there is a problem that a burr or a step is likely to be generated at the boundary with the masking portion, and the resin tube is easily damaged by the burr or the step. It is possible to remove burrs and steps by repair, but in this case, it is not desirable because the repair range is wide and the quality is adversely affected.

  The present invention has been developed in order to solve the above-mentioned problems, and the object is to apply a thin coating on the inner peripheral surface by powder coating and to apply a thick coating on the outer peripheral surface. It is possible to improve the corrosion resistance while reducing the cost, while maintaining the corrosion resistance and improving the joint strength and sealability without damaging the resin pipe, it is possible to connect the tightening ring for connecting valves and fittings, its powder coating method and The purpose is to provide valves and fittings.

  In order to achieve the above-mentioned object, the invention according to claim 1 has a transition region that transitions from both end surfaces of the outer peripheral portion of the cylindrical ring body to the inner peripheral portion, and has a predetermined film thickness on the outer peripheral portion and both end surfaces. It is a tightening ring for connecting valves and fittings that has been subjected to powder coating and has a transition coating that gradually transitions from the both end faces toward the inner periphery in the transition area.

  According to a second aspect of the present invention, there is provided a valve / joint connection fastening ring in which at least coating is not applied to a concave edge portion for preventing retaining provided in an inner peripheral portion of the ring body.

  The invention according to claim 3 is the tightening ring for connecting a valve and a joint, wherein the transition region is a tapered surface having a radially outward diameter between both end faces and the inner peripheral portion.

  According to a fourth aspect of the present invention, in the tightening ring, a powder coating having a predetermined film thickness is applied to the outer peripheral portion and both ends of the ring main body, and a powder coating is applied to the transition region so that the thickness gradually changes. This is a powder coating method for a fastening ring in which a thin film thickness is applied to the inner peripheral portion so as to give a dimensional accuracy and controlled so as not to damage the soft synthetic resin tube when fitted.

  The invention according to claim 5 is a powder coating method of a tightening ring in which at least a coating is not applied to a concave edge portion for preventing retaining provided on an inner peripheral portion of a ring main body through an appropriate jig. is there.

  According to a sixth aspect of the present invention, a soft synthetic resin pipe is fitted into the outer peripheral surface of the connection socket of the valve main body or the joint main body, and the resin pipe is fastened to the connection socket by tightening the outer periphery of the resin pipe with a tightening ring. A fixed valve and pipe fitting.

  According to the first aspect of the present invention, the outer peripheral portion and both end faces of the cylindrical ring body are powder-coated, and the transition coating film gradually and gradually becomes thinner in the transition region transitioning from the both end faces of the outer peripheral portion to the inner peripheral portion. By applying, a thin coating film can be provided on the cylindrical ring main body toward the inner peripheral portion by powder coating conforming to the standard while suppressing cost. Therefore, the resin pipe can be connected without damaging the outer periphery by preventing the step and burrs between the inner periphery and the coating film, and high corrosion resistance is ensured. With the transfer coating film, the dimensional accuracy of the inner periphery can be secured, and the joining strength and sealing performance can be improved by the minimum necessary powder coating. The thickness of the powder coating on the outer periphery that is in contact with the air and soil can be increased, which makes quality control easier and improves corrosion resistance, unlike plating processes that tend to generate cracks and pinholes. .

  According to the invention which concerns on Claim 2, a resin tube can be directly connected to this concave edge part, and a firm connection can be implemented by not coating at least the concave edge part. Since there is no possibility that the powder coating is peeled off when the resin pipe is connected, it can be connected while maintaining a high sealing property, and at the same time, the resin pipe bites into the ring body and is difficult to come off.

  According to the invention of claim 3, by making the transition region a tapered surface, the occurrence of burrs and steps due to powder coating on the inner peripheral portion is prevented, and the resin tube is prevented from being damaged when the resin tube is connected. Sealing performance after connection can be ensured while suppressing aging damage of the tube. While preventing the occurrence of irregularities on the inner periphery due to powder coating, ensure the dimensional accuracy of the inner periphery, and minimize the compression width in the thickness direction of the resin tube to increase the compression accuracy when connecting the resin tube And the insertion load can be reduced.

  According to the invention which concerns on Claim 4, a thin coating film can be provided by the powder coating based on a specification, suppressing the cost of a clamping ring. A coating film can be provided on the inner peripheral part without generating a step or a burr, and a resin pipe can be connected without damaging the outer periphery to ensure high corrosion resistance. Dimensional accuracy can be ensured on the inner peripheral side and the bonding strength and sealing performance can be improved by the minimum necessary powder coating, and the film thickness of the powder coating on the outer peripheral portion on the contact side with the atmosphere and soil can be increased on the outer peripheral side. Unlike the plating process, which can be made thicker and the film thickness is thin and cracks and pinholes are likely to occur, quality control is easy and corrosion resistance can be improved.

  According to the invention of claim 5, it is possible to prevent at least the concave edge portion from being coated through an appropriate jig, and prevent the powder coating from peeling off when the resin pipe is connected to ensure a high seal. However, it is possible to provide a tightening ring to which the resin pipe can be connected.

  According to the invention according to claim 6, it is possible to integrate while securing high corrosion resistance by using a tightening ring having a thin film coated with a powder coating conforming to the standard while suppressing cost, bonding strength and seal It can be installed in an appropriate flow path while improving the performance. The resin pipe can be clamped and fixed with a powder-coated fastening ring on a connection socket provided on the powder-coated valve body or a joint socket that is a joint body. A sense of unity in appearance can be enhanced, and the product value is also increased due to its superior beauty.

It is a partially cutaway sectional view showing an example of a valve. It is a principal part expanded sectional view of FIG. It is a perspective view which shows a clamping ring. FIG. 5 is an enlarged cross-sectional view showing a part of the tightening ring omitted. It is a schematic diagram which shows an example which mounted | wore the clamping ring with the jig | tool. It is a schematic diagram which shows the other example which mounted | wore the clamping ring with the jig | tool.

  Hereinafter, a tightening ring for connecting a valve and a pipe joint according to the present invention, a powder coating method thereof, a valve and a pipe joint will be described with reference to the drawings. In the present embodiment, as shown in FIG. 1, the valve main body 1 is composed of a soft seal gate valve for water supply, and an example in which a soft synthetic resin pipe 2 composed of a polyethylene pipe or the like is connected to the valve main body 1 is shown. A connection socket 5 which is a connection portion of a resin pipe is formed at both ends of the valve box 3 of the valve body 1, and the resin pipe 2 is connected to the connection socket 5 by a cylindrical fastening ring body 10 for fastening. The As shown in FIG. 2, the resin pipe 2 is fitted on the outer peripheral side of the connection socket 5, and the ring body 10 is fitted on the outer peripheral side of the resin pipe 2 to connect the resin pipe 2. In addition to providing the connection socket 5 as a connection portion of the valve body 1 such as a gate valve, a joint body of a pipe joint can be provided as the connection socket. Furthermore, the connection socket is not limited to the connection part of the valve body and the joint body of the pipe joint, and can be provided as a connection part of various devices.

  The ring body 10 shown in FIG. 3 is made of, for example, a metal such as a steel pipe. The ring body 10 is provided with end surfaces 16 and 16 following the outer peripheral portion 15, and the inner peripheral portion 18 is formed from the both end surfaces 16 and 16. A region to be shifted to is formed as a transition region 17. In the present embodiment, the transition region 17 is provided as a taper surface having an outwardly expanded diameter between both end surfaces 16, 16 and the inner peripheral portion 18. In this way, if the transition region 17 is a tapered surface, the transition region 17 can be provided as a boundary with the end surface 16, but the transition region 17 is transitioned from both end surfaces 16, 16 of the outer peripheral portion 15 to the inner peripheral portion 18. In the case of a region, the transition region 17 does not necessarily have a tapered surface. Therefore, the transition region 17 may be a corner or a rounded surface that transitions from the end surface 16 to the inner peripheral portion 18.

  In the case where the transition region 17 is formed by a tapered surface, it is preferable that the transition region 17 is provided at an appropriate taper angle at which a transition coating film 31 described later is easily formed when powder coating is applied to the ring body 10. Furthermore, it is desirable that the taper angle of the tapered surface 17 on the insertion side of the ring body 10 into the resin tube 2 is an angle that has little resistance when inserted into the resin tube 2 and is unlikely to damage the outer periphery 2 a of the resin tube 2. Therefore, as shown in FIG. 2, the taper angles of the taper surfaces 17 and 17 on both sides may be different.

  A plurality of groove portions 19 are formed in an annular shape on the inner peripheral portion 18 of the ring body 10, and a concave edge portion 20 for preventing the resin tube 2 from coming off is formed in the groove portion 19. The groove portion 19 is preferably provided in the vicinity of the tapered surface 17 on the insertion side to the resin tube 2.

  When the outer peripheral portion 15 side of the ring body 10 is an outer peripheral region and the inner peripheral portion 18 side is an inner peripheral region, the transition region 17 described above is shown as in FIG. 4, and the outer peripheral region 15, the inner peripheral region 18, and the transition region The coating film 30 is applied to 17 by powder coating. At this time, powder coating having a predetermined film thickness is applied to the outer peripheral portion 15 and both end surfaces 16, 16, and the transition region 17 gradually and gradually transitions from the both end surfaces 16, 16 toward the inner peripheral portion 18. A transition coating 31 is applied. The coating film 30 is provided with an appropriate resin material or the like, and in this example, powder coating is applied with an epoxy resin.

  In this case, the coating film 30 on the outer peripheral portion 15 becomes a surface in contact with a corrosive environment such as soil, and the film thickness on the outer peripheral portion 15 side may be set to, for example, 0.15 mm or more from the standard of JWWA B120. On the other hand, since the inner peripheral part 18 is a fitting part and is excluded in the film thickness regulation, in the present embodiment, the coating film 30 on the inner peripheral part 18 side has a film thickness of 0.15 mm or less with a target of 0.10 mm. It is thinly formed. Furthermore, the taper surface 17 only needs to have a film thickness between the outer peripheral part 15 and the inner peripheral part 18, and in this case, the taper surface 17 may be provided with a substantially constant film thickness in addition to gradually decreasing in thickness. .

  When the coating film 30 including the transition coating 31 that moves from the both end faces 16 and 16 of the outer peripheral portion 15 to the inner peripheral portion 18 side through the transition region 17 is applied, at least the concave edge portion 20 of the groove portion 19 is coated. Do not apply. Thereby, when the ring main body 10 is fitted and attached to the outer periphery of the resin tube 2, the coating film 30 on the inner peripheral portion 18 side other than the groove portion 19 comes into contact with the outer periphery 2 a of the resin tube 2.

  When the ring body 10 is to be painted, powder coating having a predetermined film thickness is applied to the outer peripheral portion 15 and both end faces 16 and 16 of the ring body 10, and the transition region 17 is gradually and gradually transitioned to a thin powder coating. In addition, the coating film 30 is applied to the inner peripheral portion 18 with a thin film thickness that can provide dimensional accuracy and is controlled so as not to damage the resin tube 2 when fitted.

  In this case, the concave edge portion 20 for preventing the retaining provided on the inner peripheral portion 18 of the ring main body 10 is not coated through an appropriate jig. FIG. 5 shows an example of a jig. If the groove body 19 including the concave edge portion 20 is masked by the jig 35 and the ring body 10 is coated with powder, it is ensured. Powder coating on the concave edge portion 20 is prevented.

  The jig 35 has a substantially disc-shaped paint guard part 36 and a support rod 37, and the paint guard part 36 is mounted so as to cover the groove part 19 including the concave edge part 20 of the inner peripheral part 18. This vicinity is supported, and the coating guard 36 prevents powder coating on the groove 19. The support rod 37 is formed to be branched from the paint guard portion 36 at a predetermined distance from the paint guard portion 36, and the ring main body 10 is supported by supporting both sides of the inner peripheral portion 18 with the support rod 37 and the paint guard portion 36. Is adjusted.

  Powder coating is performed with the jig mounted, and electrostatic powder coating is employed as the powder coating. At that time, after the ring main body 10 as an object is passed through a high-temperature furnace to remove moisture, gas and the like in advance before painting, powder of powder coating in which a charge different from that of the ring main body 10 is charged by a high voltage is used. The ring body 10 is directly sprayed and electrostatically attached by an injection nozzle (not shown). The attached coating film dissolves and forms a coating film when the ring body 10 is in a high temperature state.

  The outer peripheral portion 15 of the ring body 10 is coated so that the spray nozzle is directed directly toward the outer peripheral portion 15 so as to have a film thickness of 0.15 mm or more, and the jet nozzle is not directly directed on the tapered surface 17 which is a transition region. The paint is applied so that the coating film is scattered. Since the coating film scattered around is charged, it attracts and adheres to the charged electric charge on the inner peripheral portion 18. In this case, since the charge is strong in the outer peripheral portion 15 and weakly charged in the inner peripheral portion 18, the inner peripheral portion 18 has less adhesion than the outer peripheral portion 15, and controls the amount of coating film to be scattered. By doing so, the film thickness of the inner peripheral portion 18 can be suppressed to 0.15 mm or less.

  At this time, the coating guard portion 36 mounted in the vicinity of the groove portion 19 is provided with a gradient surface 38 on both outer diameter sides so that the coating film thickness can be smoothly changed. As the value approaches 20, the gap between the coating guard 36 and the ring body 10 decreases. For this reason, it becomes a structure which is hard to be charged, and the coating film which scatters to the surroundings hardly reaches the concave edge portion 20 located in the vicinity of the center of the coating guard portion 36, so that the corner of the concave edge portion 20 can be obtained by powder coating. It is possible to paint with a level that does not curl.

  In this way, a very thin film thickness is formed in the vicinity of the inner edge 18a of the inner peripheral portion 18 via the transition coating film 31 on the tapered surface 17, and burrs between the coating film 30 near the inner edge 18a and the inner peripheral portion 18 are reduced. A step can be prevented.

  FIG. 6 shows another example when the jig is mounted on the tightening ring. In this jig 40, a cylindrical extending portion 41 is formed from the coating guard portion 36, which is a support portion on one end side of the ring body 10, to the vicinity of the other end side of the ring body 10. An annular support portion 42 is formed to protrude. The ring main body 10 is supported in the vicinity of both sides of the inner peripheral portion 18 by these support portions 42 and the coating guard portion 36, and the substantially inner peripheral portion 18 except for the vicinity of the tapered surfaces 17, 17 on both sides is masked. Thereby, the coating film 30 can be applied to the outer peripheral portion 15 and the tapered surface 17 while minimizing the film thickness toward the inner peripheral portion 18 side, and the bonding strength and the sealing performance can be further increased.

  By providing the jig 40 with the axial width adjusted in this way, the range of the coating film 30 can be set to an arbitrary width. Furthermore, as a control of the coating amount of the inner peripheral portion 18, the coating guard portion 36 is set. It is also possible to adjust the film thickness of the coating film 30 on the tapered surface 17 that is a transition region by adjusting the gap between the ring body 10 and the length of the gradient surface 38 to make it more difficult to be charged.

  On the other hand, in the valve body 1 to which the resin pipe 2 is connected, the valve box 3 is formed of cast iron, for example, and the same material as the ring body 10 as a rust-proof powder coating on the outer peripheral surface including the connection socket 5. The epoxy resin is given. An annular concavo-convex portion 11 is formed on the outer periphery of the connection socket 5, and the concavo-convex portion 11 increases the bonding strength with the resin tube 2 and can prevent the detachment.

  When connecting the resin tube 2 to the valve body 1, first, the resin tube 2 is fitted into the outer peripheral surface 5 a of the connection socket 5 from the front end side, and the outer periphery 2 a of the resin tube 2 is tightened with the ring body 10. Then, the resin tube 2 is fastened and fixed to the connection socket 5. This operation is performed using an appropriate tool, whereby the resin tube 2 is strongly tightened by the ring body 10, and the concave and convex portions 11 bite into the inner peripheral side and the concave edge portion 20 bites into the outer peripheral side, respectively. . With this mechanical joining, the valve body 1 and the resin pipe 2 can be connected while strengthening the joint strength, and even when a large detachment force is applied due to an earthquake or the like, the resin pipe 2 is prevented from coming off and constriction due to stress concentration occurs. It is possible to prevent the resin tube 2 from being broken.

  In this case, since the powder coating is not applied to at least the concave edge portion 20, the resin tube 2 strongly bites into the concave edge portion 20 and can be firmly connected. Therefore, the connection strength is improved, and even if the diameter of the resin tube 2 is reduced due to secular change or the like, the resin tube 2 can be prevented from being loosened or detached.

As described above, in the tightening ring of the present invention, the region that transitions from the both end surfaces 16 and 16 of the outer peripheral portion 15 of the ring body 10 to the inner peripheral portion 18 is the transition region 17, and the outer peripheral portion 15 and both end surfaces 16 and 16 are. Is applied with a powder coating having a predetermined film thickness, and a transition coating 31 is applied to the transition region 17 which gradually and gradually transitions from the both end faces 16 and 16 toward the inner peripheral portion 18 side. The thickness of the coating film 30 on the 18th side can be reduced, and the thickness of the ring body 10 after powder coating is set within an allowable range that allows the resin pipe 2 to be properly fitted. The resin pipe 2 can be connected with a desirable fitting force while controlling the compression width of the pipe 2 in the thickness direction. Therefore, the joint strength and sealing performance after the resin pipe 2 is connected can be ensured, and the coating film 30 on the inner peripheral portion 18 is not peeled off. Therefore, even when the valve body 1 is embedded, the occurrence of rust and corrosion is prevented for a long time. High corrosion resistance can be demonstrated.
Since no burrs or steps are generated between the inner peripheral portion 18 and the coating film 30, the connection can be made while ensuring high sealing performance without damaging the outer periphery 2 a of the resin tube 2.

  Further, stress is accumulated on the distal end side of the resin tube 2 due to the ironing when the ring body 10 is fitted, and even if this stress returns with time, the forward and backward movement of the ring body 10 does not occur. Therefore, the connection strength is prevented from being lowered.

  According to the above-described tightening ring coating method, the coating film 30 can be easily provided at a predetermined position on the ring body 10 with high accuracy by using powder coating that is less expensive than plating. Since it is a coating, the occurrence of cracks and pinholes as in the case of plating treatment can be prevented and the corrosion resistance can be improved.

  Since the resin tube 2 is fitted into the outer peripheral surface 5a of the connection socket 5 of the valve body 1, and the outer periphery 2a of the resin tube 2 is fastened by the ring body 10, the resin tube 2 is fastened and fixed to the connection socket 5. Since the inner and outer surfaces of the valve body 1 are powder-coated, when the ring body 10 is applied with powder coating equivalent to the valve body 1, the valve body 1 has an external appearance and has a commercial value. Rise.

  The present invention is not limited to the above description of the embodiment, and various modifications can be made without departing from the spirit of the invention described in the claims of the present invention. For example, it can be provided as a fastening ring corresponding to a connection socket provided in a part of a piping member other than a valve or a pipe joint or other various devices. Further, in any case, the connection socket can be provided integrally or separately.

DESCRIPTION OF SYMBOLS 1 Valve body 2 Resin pipe 2a Outer periphery 5 Connection socket 5a Outer peripheral surface 10 Ring main body 15 Outer peripheral portion (outer peripheral region)
16 End face 17 Tapered face (transition area)
18 Inner circumference (inner circumference area)
20 Concave edge 30 Coating film 31 Transition coating 35 Jig

Claims (6)

  A region transitioning from both end surfaces of the outer peripheral portion of the cylindrical ring body to the inner peripheral portion is defined as a transition region, and powder coating having a predetermined film thickness is applied to the outer peripheral portion and both end surfaces. A tightening ring for connecting valves and fittings, which is provided with a transition coating that gradually and gradually transitions from the surface toward the inner peripheral side.   2. The valve / fitting coupling tightening ring according to claim 1, wherein at least coating is not applied to a concave edge portion for preventing retaining provided on an inner peripheral portion of the ring body.   The valve / fitting joint fastening ring according to claim 1, wherein the transition region is a tapered surface having an outwardly expanding diameter between the both end faces and the inner peripheral portion.   The fastening ring according to any one of claims 1 to 3, wherein a powder coating having a predetermined film thickness is applied to an outer peripheral portion and both end faces of the ring main body, and the transition region is gradually and gradually transitioned thinly. A tightening ring is applied to the inner peripheral portion with a thin film thickness that can provide dimensional accuracy and is controlled to such an extent that the soft synthetic resin tube is not damaged when fitted. Powder coating method.   The powder coating method for a tightening ring according to claim 4, wherein at least coating is not performed on a concave edge portion for preventing retaining provided on an inner peripheral portion of the ring body through an appropriate jig.   A soft synthetic resin pipe is fitted on the outer peripheral surface of the connection socket of the valve body or the joint main body, and the outer periphery of the resin pipe is fastened with the fastening ring, and the resin pipe is fastened and fixed to the connection socket. The valve and pipe joint according to any one of claims 1 to 5.

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