Fittings

Abstract

The present invention addresses the problem of providing a joint with which there is no occurrence of seizing of a tapered part of a surface-treated body during installation of piping.　This joint comprises: a body 2 in which a tapered portion 20 is formed on at least one edge inner peripheral surface of the body, threaded portions 21 are formed on an outer peripheral surface of the body, and a flow path is formed in the body; a ring 4 having a tapered outer peripheral surface 40 which makes sliding contact with the tapered portion 20 of the body 2; and a nut 3 which, among the threaded portions 21 of the body 2, is screw-fitted to a parallel threaded portion 21a on a side where piping 6 is connected, the nut pressing the tapered outer peripheral surface 40 of the ring 4 against the tapered surface 20 of the body 2, wherein the body 2 is surface treated to prevent adsorption of liquid on the surface thereof, and the surface of the ring 4 is subjected to a gold plating treatment.

Description

Technical Field

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[0001] The present invention relates to a joint for connecting pipes, and more particularly to a joint that requires surface treatment such as water repellent treatment on the body of the joint.

Background Art

[0002] Joints for connecting metal pipes are proposed that are composed of a cylindrical body with male threads formed at both ends, a ring having a tapered outer peripheral surface that slidably contacts the tapered portions on the inner surfaces at both ends of the body, and the tip of which is reduced in diameter along the taper to bite into the pipe, and a nut that screws onto the male threads of the body and presses the tapered surface of the ring against the tapered surface of the body. These joints are widely used in general industrial fields.

[0003] And in this conventional joint, from the viewpoint of firmly fixing the pipe and preventing leakage of the fluid flowing inside to the outside, the ring is divided into a front ring that slidably contacts the body tapered surface and a backup ring that directly receives the pressing force from the nut (see, for example, Patent Documents 1 to 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] There are cases where it is necessary to protect these joints from the fluids used and the environment and atmosphere in which the pipes are installed. For example, there are cases where it is necessary to prevent adsorption of water, sulfur, etc., surface modification treatment for improving corrosion resistance, film formation treatment (for example, chemical vapor deposition (chemical vapor growth (CVD))), etc.

[0006] When surface treatment, particularly chemical vapor deposition, is applied to the joint surface, depending on the vapor deposition component used (e.g., amorphous silica), tightening the nut and bringing the ring into strong sliding contact with the tapered surface of the body can cause seizing of the tapered portion of the body, as shown in Figure 6. This seizing of the body poses a problem as it can cause leakage of the fluid flowing through the piping to the outside. Another option is to mask the tapered portion of the body before surface treatment, but this requires the installation of a special jig, making the work complicated and increasing costs.

[0007] The present invention has been made in view of the above, and aims to provide a joint in which the tapered portion of the surface-treated body does not seize up when the pipe is installed. [Means for solving the problem]

[0008] The joint according to the present invention, which was made to solve the above problems, comprises a body having a tapered portion on the inner circumferential surface of at least one end and a threaded portion on the outer circumferential surface, and having a flow path inside; a ring having a tapered outer circumferential surface that slides against the tapered portion of the body; and a nut that is screwed onto the threaded portion of the body and presses the tapered outer circumferential surface of the ring against the tapered surface of the body. The body is subjected to a surface treatment to prevent liquid adsorption, and the surface of the ring is gold-plated.

[0009] The joint of the present invention successfully suppresses seizure caused by a ring that slides and rotates in contact with the tapered surface of a body that has undergone surface treatment such as chemical vapor deposition, by applying a gold plating treatment to the ring surface, which was discovered through diligent research by the inventors.

[0010] In this case, the surface treatment can be performed by chemical vapor deposition. For example, amorphous silica can be used as the deposition component.

[0011] In this case, the ring can consist of a front ring that slides against the tapered surface of the body and a backup ring that is positioned between the front ring and the annular bottom surface of the nut. [Effects of the Invention]

[0012] The present invention provides a joint that effectively suppresses seizing that occurs during pipe installation when the tapered portion of a body, which has been treated with a water-repellent coating on its entire surface by a chemical vapor deposition method, is installed. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional front view showing a joint according to the first embodiment of the present invention, where (a) shows the state before pipe fastening and (b) shows the state after pipe fastening with the tip of the ring biting into the pipe. [Figure 2] This is a cross-sectional front view showing a joint according to a second embodiment of the present invention, indicating the state before the pipes are fastened. [Figure 3] This is a cross-sectional front view showing a joint according to the third embodiment of the present invention, indicating the state before the pipes are fastened. [Figure 4] This is a cross-sectional front view showing a joint according to the fourth embodiment of the present invention, indicating the state before the pipes are fastened. [Figure 5] This is a magnified photograph of the tapered portion of the body after the nut has been loosened following the fastening of the pipes using the fitting of the present invention. [Figure 6] The photos show the tapered section of the body of a fitting that has been surface-treated but whose nuts have not been gold-plated. The nuts are loosened after the fitting has been fastened to the pipe, and (a) shows the entire tapered section, (b) is a close-up of section b in (a), and (c) is a close-up of section c in (a). [Modes for carrying out the invention]

[0014] Hereinafter, a preferred embodiment of the joint according to the present invention will be described with reference to the drawings. The shape of the components described in this embodiment, their relative arrangements, etc. are not intended to limit the scope of the present invention as long as there is no specific description, but are merely illustrative examples. Also, for convenience, the directions of members may be referred to as up, down, left, and right according to the directions on the drawings, but these do not limit the scope of the present invention.

[0015] <Embodiment 1> FIG. 1 shows a joint according to the first embodiment of the present invention. FIG. 1 shows a cross-sectional front view of the joint 1 of the present invention. FIG. 1(a) shows the state before pipe fastening, and (b) shows the state after pipe fastening where the tip of the ring bites into the pipe. This joint 1 includes a cylindrical body 2 having threaded portions 21 on the outer peripheral surfaces at both ends and a tapered portion 20 formed on the inner peripheral surface of at least one end, a ring 4 having a tapered outer peripheral surface 40 that slidably contacts the tapered portion 20 of the body 2, and a nut 3 that is screwed onto the parallel threaded portion 21a on the side where the pipe 6 is connected among the threaded portions 21 of the body 2 and presses the tapered outer peripheral surface 40 of the ring 4 against the tapered surface 20 of the body 2.

[0016] The body 2 is a cylindrical body into which the end of the pipe 6 is inserted and forms a flow path 22 through which fluid can flow. It has, for example, a hexagonal clamping portion 23 in the central part for fixing the body 2 with a tool or the like, and forms parallel threaded portions 21a, 21a onto which the nuts 3 are screwed at both ends.

[0017] And, on this body 2, as a water repellent treatment, a surface treatment for preventing the adsorption of liquid is applied to its surface. A film is formed as the surface treatment. This film formation method is not particularly limited, and examples include chemical vapor deposition (CVD) such as chemical vapor deposition method. Also, a physical vapor deposition (PVD) method can be adopted.

[0018] The CVD method is a film formation method using a chemical reaction that makes full use of a technique for transporting raw materials and reaction products in the viscous flow region. As the vapor deposition component to form the film, for example, amorphous silica or the like can be used. Further, the chemical reaction by CVD is induced by heat, light, plasma, etc., but in the present invention, the method is not particularly limited.

[0019] The material of the body 2 is not particularly limited as long as it is made of metal, but for example, stainless steel (such as SUS316) is used.

[0020] In the present embodiment, screw portions 21 are formed at both ends of the body 2. As described above, this screw portion 21 is a parallel screw portion 21a that engages with the parallel screw portion 31 formed on the inner peripheral surface of the nut 3.

[0021] The nut 3 forms an annular bottom portion 33 on the bottom surface and constitutes an insertion port 32 that allows the passage of the pipe 6. The annular bottom portion 33 presses the ring 4 toward the body 2 by screwing the parallel screw portion 31 formed on the inner peripheral surface of the nut 3 onto the parallel screw portion 21a of the body 2.

[0022] The outer peripheral surface of the ring 4 is a tapered outer peripheral surface 40 having a taper angle θ2 (for example, 30°) that is gentler than the taper angle θ1 (for example, 40°) of the tapered surface 20 of the body 2, and the inner diameter is an annular member having substantially the same diameter as the insertion port 32 of the nut 3 described above.

[0023] And at least the tapered outer peripheral surface 40 of the ring 4 is subjected to a gold plating treatment. The thickness of the gold plating is not particularly limited, but in the present embodiment, it is 0.01 μm to 0.8 μm, preferably 0.1 μm to 0.5 μm. Generally, gold plating is divided into hard gold plating and pure gold plating (soft gold plating), and either type of gold plating may be used, but in the present embodiment, hard gold plating with high film hardness is adopted.

[0024] After securing the piping using the gold-plated ring 4, the nut 3 was loosened, and a photograph of the tapered portion 20 of the body 2 was observed, as shown in Figure 5. Compared to the photograph in Figure 6(a) which shows the ring without gold plating, it can be confirmed that no seizing has occurred.

[0025] <Embodiment 2> Figure 2 shows a joint according to a second embodiment of the present invention. In this joint 1A, the ring 4 of Embodiment 1 is used as the front ring 4, and a backup ring 5 is positioned between the front ring 4 and the annular bottom portion 33 of the nut.

[0026] Similar to Embodiment 1, the front ring 4 has a tapered outer surface 40, and also has a tapered inner surface on the nut 3 side.

[0027] Furthermore, a tapered surface is formed on the outer circumferential surface of the backup ring 5 on the front ring 4 side. By screwing the parallel thread portion 31 formed on the inner circumferential surface of the nut 3 into the parallel thread portion 21a of the body 2, the backup ring 5 is directly pressed while the front ring 4 is pressed against the tapered outer circumferential surface 40 of the body 2. At this time, the tip of the front ring 4 bites into the pipe 6, and the tip of the backup ring 5 also bites into the pipe 6 in the same way as the tip of the front ring 4. As the amount of biting increases, the holding force of the pipe increases, as does the tightening resistance, and the tightening torque increases.

[0028] <Another embodiment> Figures 3 and 4 show a joint according to another embodiment of the present invention.

[0029] The joint 1B shown in Figure 3 has a body 2B at one end that is shaped similarly to Embodiment 2 and configured to accommodate a nut 3, while the other end has a tapered threaded portion 21b that screws directly into a piping block or the like. A union male threaded portion may be formed instead of this tapered threaded portion 21b.

[0030] Furthermore, while body 2B is shown as an example of a straight pipe shape, it can also be an elbow shape or a 45° elbow shape.

[0031] The joint 1C shown in Figure 4 has a T-shaped body 2C with three ends. Alternatively, the body 2C can be made cross-shaped to form four ends.

[0032] Furthermore, each end can be a tapered threaded portion 21b, as in joint 1B, or a union male portion. [Industrial applicability]

[0033] The joint according to the present invention can be suitably used as a joint for piping that handles fluids requiring surface treatment such as water-repellent treatment, and can be suitably used, for example, as a joint for connecting piping in petroleum and petrochemical plants and analytical instruments. [Explanation of symbols]

[0034] 1. Fitting 2 Body 20 Tapered section 21 Screw part 3 nuts 4 Rings (Front Rings) 40 Tapered outer surface 5 buckling 6 Piping

Claims

1. A body having a tapered portion formed on the inner circumferential surface of at least one end, a threaded portion formed on the outer circumferential surface, and a flow path inside, A ring fitted into a pipe having a tapered outer surface that slides against the tapered portion of the body, A joint comprising a nut that opens an insertion port allowing the passage of the aforementioned pipe and is screwed onto the threaded portion of the body, thereby pressing the tapered outer surface of the ring against the tapered portion of the body, A fitting having an amorphous silica film formed on the tapered portion of the body to prevent liquid adsorption, and a gold plating layer formed on the tapered outer surface of the ring.

2. The joint according to claim 1, wherein the ring comprises a front ring that slides against the tapered portion of the body and a backup ring disposed between the front ring and the annular bottom surface of the nut.

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