JPH0211674Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is based on the idea that when a lining pipe, in which the inner peripheral surface of a metal pipe is coated with a synthetic resin layer, is connected to the joint body,
This invention relates to a corrosion-resistant pipe joint in which the joint is hermetically sealed to prevent metal parts from corroding.

(Prior art) As this type of corrosion-resistant pipe joint, for example,
There is a corrosion-resistant pipe joint proposed in Publication No. 83789.

This pipe fitting has a structure in which a synthetic resin cylindrical body with a female thread on the inner circumference of the end is fitted into the inner part of the metal pipe fitting body with a female thread on the inner circumference of the end. The fifth example shows an example of the
In the figure, a protruding piece is provided integrally from the protruding strip provided on the inner surface of the synthetic resin cylindrical body, and an inner-coated steel pipe (lining pipe) is inserted into the gap between the protruding piece and the female threaded part, and the threaded screw is inserted. Corrosion-resistant pipe fittings are shown.

(Problem that the invention aims to solve) However, this corrosion-resistant pipe joint does not have sufficient adhesion between the outer peripheral surface of the protruding piece and the inner peripheral surface of the internally coated steel pipe, and this pipe joint is used for high-pressure fluid transportation piping. In this case, there was a problem in that the fluid inside the pipe entered through this small gap and corroded the end portion of the inner-coated steel pipe and the male threaded portion provided on the outer circumferential surface thereof.

The present invention solves the problems of conventional pipe joints, and has excellent workability, and is corrosion-resistant, with no risk of corrosion of the end of the lining pipe and the male threads provided on its outer circumferential surface after connection. It provides pipe fittings.

(Means for Solving the Problem) The present invention covers the inner circumferential surface of a metal joint having a female thread at the end with a synthetic resin layer of a predetermined thickness except for the female thread, and extends from the synthetic resin layer. It is comprised of a joint body with a gap of a predetermined width provided between the cylindrical part and the female thread, and a lining tube in which the inner circumferential surface of a metal tube is coated with a synthetic resin layer. The outer circumferential surface of the cylindrical portion is made approximately equal to the inner diameter of the lining pipe, and a clearance is provided at the inner part of the gap between the cylindrical portion and the female thread.

On the other hand, a male thread is provided at the end of the lining pipe, and the male thread is screwed into the female thread of the joint body, so that the tip of the lining pipe escapes through the gap, and the inner peripheral surface of the lining pipe and the outer peripheral surface of the cylindrical part It is characterized by having an adhesive interposed between the two.

Hereinafter, the specific configuration of the present invention will be explained in detail based on examples.

〔Example〕

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, in which reference numeral A denotes a joint body, and B denotes a lining tube in which the inner circumferential surface of a metal tube 3 is coated with a synthetic resin layer 4.

The joint body A has a metal joint 1 having a tapered female thread 11 at its end, and covers the inner circumferential surface of the metal joint 1 with a synthetic resin layer 2 having a predetermined thickness, except for the female thread 11, and extends from the synthetic resin layer 2. The cylindrical body 21 and the female thread 1
1, with a gap of a predetermined width provided therebetween.

The joint body A is integrally formed by injection molding, and the cylindrical portion 21 extends from the synthetic resin layer 2 and is formed substantially flush with the inner peripheral surface thereof. The inner surface of the tip end of the cylindrical portion 21 is a tapered surface whose diameter increases toward the opening side. Further, the outer circumferential surface of the cylindrical portion 21 is formed to have approximately the same diameter as the inner diameter of the lining pipe B (the inner diameter of the synthetic resin layer 4). In addition, the cylindrical part 2 is shown in FIG.
Although the outer peripheral surface of the cylindrical portion 21 is illustrated as being a flat cylindrical surface, one or more protrusions continuous in the circumferential direction may be provided on the outer peripheral side of the cylindrical portion 21. When the protrusions are provided on the outer peripheral surface of the cylindrical part 21 in this way, when the lining pipe B is inserted into the cylindrical part 21, the protrusions are pressed against the inner peripheral surface of the lining pipe B. High watertightness can be obtained.

On the other hand, a gap 22 formed by cutting out the synthetic resin layer 2 is provided in the deep part of the gap formed by the cylindrical part 21 and the female thread 11, and the tip of the lining pipe B is inserted into the deep part of the gap. It has become easy to infiltrate.

The corrosion-resistant pipe joint of the present invention has the above configuration, and the lining pipe B is joined to the joint body A through the following steps.

First, a tapered male screw 31 is provided at the end of the lining tube B, and a sealing tape such as Teflon tape is wound around the outer peripheral surface of the male screw 31. Then, an adhesive is applied to the inner circumferential surface of the end of the lining tube B or the outer circumferential surface of the cylindrical portion 21 of the joint body A, and the male thread 31 of the lining tube B is screwed into the female thread 11 to connect. By this screwing operation, the tip of the lining tube B penetrates into the deep part of the gap, and the inner circumferential surface of the lining tube B and the outer circumferential surface of the cylindrical portion 21 are firmly joined via the adhesive.

By the way, when the tapered male thread 31 is provided at the end of the lining pipe B, the male thread 31 may become longer than necessary, but since the recess 22 is provided in the deep part of the gap, the lining pipe B Intrusion from the end portion is sufficiently absorbed by the cutout 22, and the joint body A and the lining pipe B are firmly screwed together.

Although Fig. 1 shows an example of a metal joint called an elbow joint, the inner peripheral surface of which is coated with a synthetic resin layer, the present invention is not limited to this elbow joint, and can also be applied to T-joints, socket joints, etc. It can be applied to various metal joints such as , end caps, etc.

On the other hand, the synthetic resin layer covering the inner circumferential surface of the metal joint may be made of vinyl chloride resin, polyethylene resin, etc., and can be appropriately selected in combination with the synthetic resin layer of the lining pipe.

In addition, as the adhesive interposed between the cylindrical part of the joint body and the lining pipe, there are various conventionally known fluid adhesives, silicone, modified silicone, urethane resin, and other relatively viscoelastic adhesives. Can be used.

(Operations and Effects of the Invention) The corrosion-resistant pipe joint of the present invention has the above-mentioned configuration, and therefore has the following advantages.

In other words, the outer circumferential surface of the cylindrical part is approximately equal to the inner diameter of the lining pipe, and a clearance is provided at the deep end of the gap between the cylindrical part and the female thread, so that when the lining pipe is screwed into the joint body and joined, The tip of the lining pipe is absorbed by the clearance and penetrates deep into the joint body, and the joint body and the lining pipe are firmly screwed together.

In addition, since the inner circumferential surface (synthetic resin layer) of the lining pipe and the outer circumferential surface of the cylindrical body are bonded via adhesive, extremely excellent watertightness is maintained, and this pipe joint can be used with high-pressure fluids. Even when used in transportation piping, there is no fear that the end of the lining pipe and the male thread provided on its outer circumferential surface will be corroded by the fluid inside the pipe.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a corrosion-resistant pipe joint showing an embodiment of the present invention. A...Joint body, B...Lining pipe, 1...
Metal joint, 11...female thread, 2...synthetic resin layer,
21...Cylindrical part, 22...Drawing, 3...Metal tube, 31...Male thread, 4...Synthetic resin layer.

Claims (1)

[Scope of utility model registration request] The inner circumferential surface of a metal joint 1 having a female thread 11 at the end is covered with a synthetic resin layer 2 having a predetermined thickness, except for the female thread 11, and a cylindrical part 21 extending from the synthetic resin layer 2 and the female thread 11 are covered. It consists of a joint body A with a gap of a predetermined width provided therebetween, and a lining tube B in which the inner circumferential surface of a metal tube 3 is coated with a synthetic resin layer 4, and the outer circumferential surface of the cylindrical portion 21 is A recess 22 is provided in the deep part of the gap between the cylindrical portion 21 and the female thread 11, and the male thread 31 is provided at the end of the lining pipe B, and the male thread 31 is connected to the female thread of the joint body A. This corrosion-resistant pipe joint is characterized in that it is screwed into the lining tube B and its tip is released with a cutout 22, and an adhesive is interposed between the inner circumferential surface of the lining tube B and the outer circumferential surface of the cylindrical portion 21.