JP3069838B2 - Pipe end corrosion protection structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe end anticorrosion structure for preventing water pollution such as red water in a water supply or hot water supply piping system using a lining steel pipe, and particularly relates to a lining steel pipe, a valve, a pipe joint, a strainer, and the like. The present invention relates to a pipe end anticorrosion structure at a connection point.

[0002]

2. Description of the Related Art In recent years, lining steel pipes whose inner surfaces are coated with a synthetic resin such as polyethylene powder lining or vinyl chloride lining are often used in water supply and hot water supply pipes to prevent red water. . However, when this lining steel pipe is screw-connected to a pipe joint, a valve, or the like (hereinafter, referred to as a connected body), the threaded portion of the steel pipe or the iron portion exposed at the end face of the pipe comes into contact with the fluid, so that the connected body and the steel pipe are connected. Corrosion of the iron part is promoted due to a potential difference caused by the contact of a dissimilar metal with the metal, and flows out into the pipe as red water.

[0003] In order to prevent the generation of this red water, various types of pipe end anticorrosion cores have been conventionally proposed. In the anticorrosion pipe joint shown in FIG. 8, a cylindrical core 2 made of synthetic resin is integrally provided on the inner peripheral surface of the pipe joint body 1, and the inner peripheral surface of the lining steel pipe 3 and the cylindrical core are formed on the outer peripheral surface of the cylindrical core 2. A rubber ring 4 having a wedge-shaped cross section for sealing between the two is mounted, and when the lining steel pipe 3 is screwed in, the wedge-shaped tip of the rubber ring 4 bites between the inner surface of the lining steel pipe 3 and the cylindrical core 2 to seal. It is a structure with character.

[0004] The anticorrosion pipe joint shown in FIG. 9 has a rubber seal 8 having a sleeve seal portion 8 between a cylindrical core 7 provided integrally with a female thread 6 of the joint 5 and on an inner peripheral surface of the joint 5. When the ring 9 is mounted and the lining steel pipe 10 is screwed in, the end of the lining steel pipe 10 and the sleeve seal portion 8 come into contact with each other to seal.

[0005]

However, these conventional examples have the following disadvantages. In the case of the anticorrosion pipe joint shown in FIG. 8, the rubber ring 4 has a wedge-shaped cross section and is directional. Therefore, when the rubber ring 4 is mounted on the cylindrical core 2, if the direction is wrong, the incorporation mistake may be caused. Become. When screwing the lining steel pipe, the lining steel pipe 3
While rotating toward the back while rotating, the cylindrical core 2 is fixed to the pipe joint body 1, so the rubber ring 4 is sandwiched between the inner surface of the lining steel pipe 3 and the outer surface of the cylindrical core 2. If the lining steel pipe 3 is screwed in this state, the thin tip portion of the wedge-shaped rubber ring 4 may be twisted or cut, so that sufficient sealing performance may not be obtained.

Further, when screwing the lining steel pipe 3,
The sealant is applied to the end face of the tube and the threaded portion. However, since the application operation is a manual operation, the application amount is not always constant. When the coating amount is large, especially in a polyethylene lining steel pipe having a large inner diameter, the wedge-shaped portion of the rubber ring 4 enters the gap between the outer surface of the cylindrical core 2 and the inner surface of the lining steel pipe 3 together with the sealing agent. The wedge-shaped portion of the rubber ring 4 may jump out of the cylindrical core 2 due to an increase in the internal pressure due to the screwing.

The rubber ring 4 needs to be inserted between the chamfered portion of the lining steel pipe 3 and the cylindrical core 2 and moved to the inner side of the cylindrical core 2 for sealing.
However, since the lining steel pipe 3 has unevenness in the treatment of the pipe end face, if the treatment is incomplete, the rubber ring 4 may be twisted, pulled, cut, etc., and the rubber ring 4 may be placed at an appropriate position. Not only did it not fit, but there was also a major problem with the sealing properties.

In addition, the anticorrosion pipe joint shown in FIG. 9 has a drawback that if the end surface of the lining steel pipe 10 to be screwed is not cut smoothly, sufficient sealing properties cannot be obtained. Furthermore, since the gap between the pipe end of the lining steel pipe 10 and the cylindrical core 7 greatly changes depending on the screwing state of the lining steel pipe 10, a sufficient sealing pressure may not be obtained particularly in a shallow case, and the screwing is excessive. In this case, the rubber ring 9 presses the cylindrical core 7, deforming the core 7 and impairing the sealing performance.

The present invention has been developed in view of the above-mentioned various problems in the prior art. The present invention eliminates a mistake in assembling, improves the assembling workability, ensures a reliable sealing performance, and also allows the lining steel pipe to be used for the core. An object of the present invention is to move the seat ring smoothly to the rear side and sufficiently exhibit sealing performance without causing twisting, pulling or cuts of the seat ring to achieve red water prevention performance.

[0010]

In order to achieve the above object, a pipe end anticorrosion structure according to the present invention comprises a valve, a pipe joint,
A female screw is provided at a connection portion of a connected body such as a strainer, a synthetic resin layer is integrally provided at the back of the female screw, and a cylindrical portion is protruded toward the connection insertion side in this synthetic resin layer, In this pipe end anticorrosion structure in which a lining steel pipe having a male screw is screwed and connected between the female screw and the cylindrical part, the thick part of the seal ring inserted into the outer periphery of the cylindrical part is formed to have a substantially arc-shaped cross section. The inner diameter of this seal ring is L,
Assuming that the sectional thickness is H, there is a relationship of L ≦ 2H , and the sealing ring is lined between the inner surface at the tip end of the lining steel tube and the outer surface of the cylindrical portion while screwing the lining steel pipe to move the seal ring to the back. A means for tightly sealing the end of the steel pipe with the pipe end is employed.

[0011] In this case, the seal ring is formed of a rubber or synthetic resin, has is preferable to the shape of the thick portion in cross section a substantially semicircular shape. The above lining steel pipe, the inner surface of the steel pipe is a steel pipe overturned be a synthetic resin such as polyethylene powder lining or polyvinyl chloride lining.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a pipe end anticorrosion structure according to the present invention is applied to a connection portion of a valve will be described below in detail with reference to the drawings. 1 and 3 are longitudinal sectional views showing an example of a state immediately before connection of the pipe end anticorrosion structure, and FIGS. 2 and 4 show a state in the middle of connection of the pipe end anticorrosion structure shown in FIGS. FIG.

In the drawing, a female screw 13 is provided at a connection portion 12 of a body 11a of a gate valve 11 which is a connected body, and a valve body 11 engaged with a stem 11b is provided therein.
c is built openably and closably. A synthetic resin layer 14 integrally formed by injection molding is provided at the back of the female screw 13, and a cylindrical portion 15 is integrally formed on the synthetic resin layer 14 so as to project toward the connection insertion side. .

A screwing space 19 for screwing the lining steel pipe 16 is provided between the female screw 13 and the cylindrical portion 15.
The lining steel pipe 16 is formed by lining a resin layer 16b on an inner peripheral surface of a steel pipe 16a, forming a chamfered portion 16c at a distal end portion of the resin layer 16b, and a female screw 13 on a distal end portion of an outer peripheral surface of the lining steel pipe 16. A male screw 17 to be screwed is provided. The lining steel pipe 16 is, for example, a polyethylene powder lining steel pipe for water supply, a hard vinyl chloride lining steel pipe, or a vinyl chloride lining steel pipe for hot water supply. Of these, the polyethylene powder lining steel pipe is a hard vinyl chloride lining steel pipe. It is lined with a thinner wall than PVC or PVC-lined steel pipe.

In FIG. 7, reference numeral 18 denotes a seal ring made of rubber or synthetic resin inserted into the outer periphery of the cylindrical portion 15. The seal ring 18 is screwed into the lining steel pipe 16 to move the seal ring 18 to the back. The chamfered portion 16c, which is the inner surface of the tip of the lining steel pipe 16, and the cylindrical portion 15
Of the lining steel pipe 16 while being tightly sealed.

The thick portion of the seal ring 18 is formed in a substantially arc-shaped cross section, and is provided with an inner peripheral surface 18a and rounded portions 18b at both ends of the inner peripheral. Seal ring 1 in this example
Reference numeral 8 denotes a seal ring 18 having a substantially semicircular cross section when its thick portion is formed, and a seal ring 18 having a substantially semicircular cross section has a relation of L ≦ 2H, where L is an inner peripheral width and H is a cross sectional thickness. In the radius 18b, a preferable result was obtained by satisfying R ≧ 0.5.

Next, the operation of the above embodiment will be described.
As shown in FIG. 1, a seal ring 18 is attached to the cylindrical body 15 of the synthetic resin layer 14. In this case, the seal ring 18
Has a semicircular cross section, the directionality is lost, the mistake of assembling is eliminated, and the assembling workability is improved.

Next, when the lining steel pipe 16 is screwed in, the seal ring 18 is moved to the inner part of the space 19 by the pipe end 16d of the lining steel pipe 16 and the inner surface of the tip of the lining steel pipe 16, as shown in FIGS. Meanwhile, the seal ring 18 exerts a sealing function while making tight contact between the chamfered portion 16c, which is the inner surface at the distal end of the lining steel tube 16, and the outer surface of the tubular portion 15 and the tube end 16d of the lining steel tube 16.

Since the seal ring 18 has a semicircular cross-section, the seal ring 18 does not enter between the chamfered portion 16c of the lining steel pipe 16 and the outer surface of the cylindrical body 15 more than necessary as compared with the wedge-shaped rubber ring 4. In addition, the sealability is ensured, the seal ring 18 does not protrude out of the cylindrical body 15 unnecessarily, and furthermore, the lining steel pipe 1 is smoothly moved.
It moves to the back of the space 19 together with 6, and it is possible to prevent the occurrence of twisting, pulling, cuts and the like.

In this case, if the lining steel pipe 16 is a polyethylene powder lining steel pipe, the lining layer (resin layer) 16b is thinner than the vinyl chloride lining steel pipe, and therefore, as shown in FIG. The seal ring 18 is crimped between the outer surface of the tubular portion 15 and the outer surface of the tubular portion 15 to securely seal.

When the lining steel pipe 16 is a vinyl chloride lining steel pipe, the lining layer (resin layer) 16b
Is thicker than the polyethylene powder-lined steel pipe, and as shown in FIG.
5 is screwed in while reducing the diameter. The seal ring 18
It is crimped between the chamfered portion 16c of the lining steel pipe 16, the pipe end 16d, and the outer surface of the tubular portion 15, and reliably exhibits sealing properties.

The above embodiment has been described with reference to an example of a gate valve. However, the present invention is not limited to this, and is widely applied to other various valves or connected objects such as pipe joints or strainers. The fluid can be widely used for fluids such as water supply and hot water supply.

[0023]

As described above, according to the present invention, corrosion pipe end structure in the present invention, it becomes possible to eliminate the incorporation errors seal ring, that compared with the prior art significantly increase the incorporation workability can not only be reliably ensure the sealing property, a lined steel pipe smoothly moved to the back side of the core twisting of seal rings, without generating tensile or cuts, etc., the sealing property There is an effect that red water prevention performance can be achieved by effectively exerting it.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a state immediately before connection of a pipe end anticorrosion structure according to the present invention.

FIG. 2 is a longitudinal sectional view showing a state in the middle of connection of the pipe end anticorrosion structure shown in FIG.

FIG. 3 is a longitudinal sectional view showing another example of a state immediately before connection of the pipe end anticorrosion structure according to the present invention.

FIG. 4 is a longitudinal sectional view showing a state in the middle of connection of the pipe end anticorrosion structure shown in FIG. 3;

FIG. 5 is an enlarged detail view of a part a of FIG. 2;

FIG. 6 is an enlarged detail view of a portion b in FIG. 4;

7 is a partial cross-sectional view showing a seal ring according to the present invention.

FIG. 8 is a partial cross-sectional view showing a conventional example of a corrosion protection pipe joint.

FIG. 9 is a partial cross-sectional view showing a conventional example of a corrosion protection pipe joint.

[Explanation of symbols]

11 the connecting body 12 connecting portion 13 internally threaded 14 synthetic resin layer 15 the tubular body 16 lined steel pipe 16c chamfer 16d tube end 17 external thread 18 seal ring 19 space

Claims (3)

(57) [Claims] 1. A female thread is provided at a connection portion of a body to be connected such as a valve, a pipe joint, a strainer, etc., and a synthetic resin layer is integrally provided at a deep portion of the female screw. In a pipe end anticorrosion structure in which a tubular part is projected toward the pipe, and a lining steel pipe having a male thread is screwed between the female thread and the tubular part to be connected, a seal ring inserted into the outer periphery of the tubular part is provided. The thick part is formed in a substantially circular cross section ,
The ring has an inner peripheral width of L and a sectional thickness of H.
And L ≦ 2H, wherein the seal ring is screwed into the lining steel pipe to move the seal ring to the back, while the seal ring is between the inner surface of the front end of the lining steel pipe and the outer surface of the cylindrical portion and the pipe end of the lining steel pipe. The end-of-pipe corrosion protection structure is characterized in that it is tightly sealed. 2. The pipe end anticorrosion structure according to claim 1, wherein said seal ring is formed of rubber or synthetic resin and has a substantially semicircular cross section. 3. The lining steel pipe according to claim 1 , wherein an inner surface of the steel pipe is provided.
Polyethylene powder lining or vinyl chloride lining
3. A steel pipe coated with a synthetic resin such as
The pipe end anticorrosion structure described .