JPH08219368A - Pipe end corrosion resistant structure - Google Patents

Abstract

PURPOSE: To provide pipe end corrosion resistant structure of high reliability improving adhesion between a core body and a connected body in piping materials so as to prevent the generation of red water. CONSTITUTION: An annular recessed part 2b and an annular step part 2c are formed at the inner part of a connecting part 2 provided at a connected body 1, and synthetic resin is injection-filled therein to form the annular base part 3a and annular protruding part 3b of a core body 3 respectively in close contact with the annular recessed part 2b and the annular step part 2c. The step part 2c prevents the generation of a clearance due to the difference between the expansion coefficients of the connected body 1 and core body 3 at the time of forming or after forming, and the close contact state of the connected body 1 and core body 3 can be kept desirably.

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 pipe system for water supply and hot water supply using a lining steel pipe, and particularly to a lining steel pipe and a valve, pipe joint or other pipe. The present invention relates to a pipe end anticorrosion structure provided at a connection point with equipment.

[0002]

2. Description of the Related Art In recent years, lining steel pipes coated with vinyl chloride, polyethylene powder, or other synthetic resin are often used for water pipes (water supply, hot water supply). In this lining steel pipe, the inner surface of the steel pipe is covered with a synthetic resin to prevent the metal portion of the steel pipe from coming into contact with water or hot water, thereby preventing corrosion (red rust).

On the other hand, in such a piping system, piping equipment such as a valve for stopping water and a pipe joint for branching are provided everywhere in the lining steel pipe. At the connection between these piping equipment and the lining steel pipe, since the pipe end of the lining steel pipe is a cut surface, the synthetic resin is not coated and the metal surface is exposed, and this part always flows in the pipe. Red rust occurs when exposed to water or warm water. Then, this red rust is mixed with water or hot water flowing through the pipe, and a so-called water or hot water pollution phenomenon called red water has been a problem.

For this reason, when connecting the lining steel pipe to the piping equipment such as valves and pipe fittings, a synthetic resin member called a core is provided at the connecting portion of these main bodies, and a pipe end that is a cut surface of the lining steel pipe is provided. A pipe end anti-corrosion structure has been proposed in which the part does not come into contact with liquid. As an example of a conventional example having such a configuration, FIG. 6 shows a gate valve having a pipe end anticorrosion structure.

In FIG. 6, 20 is a gate valve, and 21
Indicates a connecting portion, 22 indicates a core, and 23 indicates a lining steel pipe. The connecting portion 21 of the valve 20 is a fluid inlet (outlet), and a female screw portion 21a into which a male screw portion 23a formed at the pipe end portion of the lining steel pipe 23 is screwed is formed, and a concave portion is formed at the end of the female screw portion 21a. 21b is formed in a ring shape.

The core 22 arranged in the connecting portion 21 is integrally provided by an injection molding method. Recessed portion 2 of connection portion 21
An appropriate synthetic resin material (molten plastic) is injected into 1b, the base portion 22a of the core body 22 is formed into a brim shape, and the tubular portion 22b faces the opening direction of the connection portion 21.
A rear tubular portion 22c is integrally formed toward the inner portion of the main body 20. Further, a seal ring 24 is fitted on the outer circumference of the tubular portion 22b of the core 22.

The female screw portion 21a of the connecting portion 21 is
When the male screw portion 23a formed in the vicinity of the pipe end portion of the lining steel pipe 23 is screwed and screwed, the tubular portion 22 of the core 22 is formed.
b adheres closely to the lining layer 23b of the lining steel pipe 23, and the metal exposed portion 23 at the pipe end of the lining steel pipe 23
The c is in close contact with the seal ring 24 and is sealed. Thereby, the metal exposed portion 23c at the pipe end of the lining steel pipe 23
The contact with water or hot water in the lining steel pipe 23 is cut off, rust can be prevented from occurring at this portion, and red water can be prevented from occurring. Although a gate valve is shown in the figure, the various valves for water pipes provided with the core and the connecting portions of various pipe joints are configured in substantially the same manner as described above.

[0008]

However, the conventional pipe end anticorrosion structure has the following problems. The core 22 provided in the connecting portion 21 of the gate valve 20 is molded by the integral injection molding method in which the connecting portion 21 is filled with the synthetic resin melted at high temperature. In particular, when connecting a lining steel pipe 23 having a large diameter to the connection portion 21, the core 22 is also formed to have a large diameter in accordance with this, and the gate valve 20 is made of a metal such as a copper-based alloy such as bronze or brass or stainless steel. Since the core 22 is made of a material, and the core 22 is molded from synthetic resin, the expansion rates of the two members 20 and 22 are significantly different. Therefore, the core 22 made of synthetic resin has a cooling rate after molding compared to other metal parts. As a result, a shrinkage phenomenon called sink mark appears remarkably, and further, due to the shrinkage of the synthetic resin after molding, the recessed portion 21b of the connection portion 21 and the base portion 22a of the core body 22 are separated from each other as shown in the figure. Then, the gap G1 is generated.

On the other hand, the lining steel pipe 23 to the connecting portion 21
Is connected by screwing the female screw portion 21a and the male screw portion 23a, which are tapered screws formed on both members 21 and 23. Therefore, although the core 22 that is in close contact with the lining layer 23b of the lining steel pipe 23 has some elasticity, the core 22 is compressed as the lining steel pipe 23 is screwed in the centripetal direction (arrow direction in the drawing). There is also a problem in construction that the core portion 22c of the core 22 is reduced in diameter and a gap G2 is generated at this portion.

As described above, the gate valve 20 and the core 22 are
When the gaps G1 and G2 are generated between the pipes, water and hot water flowing in the pipeline enter the gaps G1 and G2, and the water and hot water are lined in the lining steel pipe 23.
It comes into contact with the exposed metal portion 23c of the pipe end, and the contacted portion corrodes, and red rust is eluted into water or warm water flowing in the pipe to become red water. As described above, it is difficult for the core 22 provided in the pipe equipment 20 having a large nominal diameter to maintain high adhesion under various conditions, and a sufficient effect cannot be obtained.

The present invention is intended to solve the problems of the above-described conventional pipe end anticorrosion structure. The object of the present invention is to prevent the generation of red water regardless of the nominal diameter. To provide the structure.

[0012]

In order to achieve the above object, the present invention integrally forms a core main body having a tubular portion at a connecting position of a body to be connected of a piping equipment member toward an opening direction of the connecting portion. In the pipe end anticorrosion structure described above, an annular recess is formed on the inner side of the connecting portion of the connected body, an annular step is formed further on the inner side of the annular recess, and the core body is formed at the connecting position of the connected body. When the insert molding is performed, a configuration is adopted in which the annular base portion provided on the core body in the annular recessed portion and the annular projection portion formed on the core body in the annular stepped portion are integrally molded in a close contact state.

In this case, the annular concave portion and the annular stepped portion formed in the connected body of the piping equipment, the edge surface, and the flow path surface to which the rear end portion of the core body following the edge surface are brought into contact with each other by grinding or the like. It is preferable to increase the adhesion of the core body.

Further, a plurality of annular step portions may be provided in the inner part of the connecting portion, and the annular step portion may be a dovetail groove. Further, it is preferable that the angle α of the annular step portion is formed to be 90 ° or less. Further, it is preferable to chamfer the edge surface of the annular step portion or the dovetail groove on the flow path side.

On the other hand, the tubular portion of the core body provided on the piping equipment body is formed into a first taper surface and a second taper surface (or a horizontal surface), and a vinyl chloride lining is formed on the connecting portion of the connected body of the piping equipment material. When the steel pipe is connected, the first taper surface and the second taper surface (or the horizontal surface) of the tubular portion are sealed while watertightly adhering in a state in which the inner peripheral surface of the vinyl chloride lining steel pipe is reduced in diameter. Further, when the polyethylene powder lining steel pipe is connected to the connection portion of the connected body of the piping equipment, the second taper surface (or horizontal surface) of the tubular portion is watertight with the inner peripheral surface of the polyethylene powder lining steel pipe. It is preferable to configure so as to closely adhere to and seal. That is, the second taper surface (or horizontal surface) of the outer diameter of the tubular portion is
It is preferable that the polyethylene powder-lined steel pipe is formed with a diameter equal to or smaller than the inner diameter.

Further, on the outer peripheral surface of the cylindrical portion of the core body described above, a wedge-shaped cross section, an elliptical cross section made of an appropriate polymer material,
It is preferable to provide a seal ring having a circular cross section, a triangular cross section, or other cross sectional shape. The above-mentioned piping equipment is a gate valve, globe valve, ball valve, check valve or other valve, socket,
Widely applied to elbow, cheese or other pipe fittings, strainers or other plumbing equipment.

[0017]

Since the present invention is configured as described above, the core body provided at the connecting portion of the connected body of the piping equipment is melted by the injection molding method into the annular concave portion and the annular step portion at the inner portion of the connecting portion. Plastic is injected and injected, the annular base of the core body is molded in close contact with the annular recess, and the annular protrusion is molded in close contact with the sealing surface of the annular step, preventing the infiltration of water or warm water at this part. To do.

In this case, when the angle α of the annular step portion formed in the inner part of the connection portion is formed to be 90 ° or less (or less), the annular step portion of the piping equipment and the annular protrusion of the core body come into contact with each other.
The diameter reduction in the centripetal direction of the core body when the lining steel pipe is screwed into the connection part is suppressed to the minimum, and the expansion coefficient difference between the metal forming the piping equipment and the synthetic resin of the core body at this part is also suppressed. Regardless, strong adhesion is obtained,
A high sealing property can be obtained. Further, such close contact between the annular step portion and the annular ridge absorbs rattling due to the difference in expansion coefficient between the metal forming the piping equipment and the synthetic resin of the core body, so that the piping equipment body has a large diameter. Even if there is, it is possible to prevent peeling of the both and the generation of a gap in this portion.

If chamfering is applied to the edge surface on the flow path side of the annular stepped portion, injection and injection of the molten plastic during molding of the core body can be carried out smoothly and evenly. Performs functions such as reliable molding. Further, if a plurality of annular step portions are provided or the annular step portions are dovetail grooves, even better sealability can be obtained. In addition, if the core body is not provided on the connected body of the piping equipment, the fluid resistance can be reduced by the edge surface formed on the connected body.

As a result, when the male screw portion formed in the vicinity of the pipe end portion of the lining steel pipe is screwed into the female screw portion formed at the connecting portion of the piping equipment and screwed in, the outer peripheral surface of the tubular portion of the core body is Watertightly adheres to the lining layer of the lining steel pipe. Along with this, the metal exposed portion of the pipe end of the lining steel pipe is closely sealed with the seal ring at the back end of the core body, so that the metal exposed portion of the pipe end of the lining steel pipe is not wetted, , Red rust does not occur in this area and red water is not generated.

Further, by tapering the tubular portion of the core body disposed at the connecting portion of the piping equipment, one core body can be used as two types of lining steel pipes, a vinyl chloride lining steel pipe and a polyethylene powder lining steel pipe. Can respond. That is, since the vinyl chloride lining steel pipe has a thicker lining layer than the polyethylene powder lining steel pipe, the inner diameter is narrow even if the outer diameter is the same. Therefore, when the vinyl chloride lining steel pipe is connected to the connecting portion of the piping equipment, the first and second taper surfaces of the tubular portion of the core body are watertightly adhered to the inner peripheral surface of the vinyl chloride lining steel pipe to seal, When the polyethylene powder-lined steel pipe is connected, the second taper surface or the horizontal surface of the cylindrical portion of the core body is watertightly sealed to the inner peripheral surface of the polyethylene powder-lined steel pipe.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pipe end anticorrosion structure of the present invention will be described with reference to the drawings. In addition, the pipe end anticorrosion structure of the present invention, gate valve, globe valve, ball valve, check valve or other valves, sockets, elbows, cheese or other pipe fittings, or various as exemplified in the strainer However, in this embodiment described below, a gate valve will be described as an example of the piping equipment.

In FIG. 1, reference numeral 1 is a main body of a gate valve (hereinafter, simply referred to as “main body”) which is piping equipment, 2 is a connecting portion, 3 is a core main body, and 4 is a lining steel pipe.
The connecting portion 2 of the main body 1 is a fluid inlet (outlet),
A female screw portion 2a into which a male screw portion 4a formed on the pipe end portion of the lining steel pipe 4 is screwed is formed.
An annular recess 2b is formed at the end of a, and an annular step 2c is formed further inside the annular recess 2b. As shown in FIG. 5, the annular step portion 2c has a sealing surface 2d formed by setting the step angle α to 90 ° or less or less, and the adhesion with the core body 3 described later is improved.

A core body 3 having a through channel is arranged in the connecting portion 2 of the body 1, but in this embodiment, it is provided by an integral injection molding method. That is, in the annular concave portion 2b and the annular stepped portion 2c formed in the connecting portion 2 of the main body 1, an appropriate synthetic resin material (molten plastic), such as hard vinyl chloride or heat resistant vinyl chloride, is used for a molding die (not shown). Alternatively, a synthetic resin material such as polybutene is injected and injected. As a result, the molten plastic will be retained in the annular recess 2b and the annular step 2c.
And the annular base 3a is formed in close contact with the annular recess 2b, and the annular protrusion 3b is formed in close contact with the sealing surface 2d of the annular step 2c. As a result, the core body 3 is provided by integrally molding the tubular portion 3c and the tubular rear end portion 3d toward the inner portion of the main body 1.

Further, since the annular groove 3g is provided at the rear end of the tubular portion 3c, when the lining steel pipe is screwed into the tubular portion 3c, when the tubular portion 3c of the core body 3 contracts, The action of the annular groove 3g ensures the elasticity of the core body 3 in the centripetal direction.

By the way, as the lining steel pipe 4 used for the water supply pipe, two types, a hard vinyl chloride lining steel pipe and a polyethylene powder lining steel pipe, are widely used as typical ones. Since the lining layer 4b-2 of the hard vinyl chloride lining steel pipe and the lining layer 4b-1 of the polyethylene powder lining steel pipe have different lining thicknesses,
Even though the outer diameter of the steel pipe is the same as shown in the figure, the inner diameter of the hard vinyl chloride lining steel pipe is narrower, so a dedicated core body was required for each, but the core body 3 of the present embodiment is The first tapered surface 3e is provided on the outer peripheral surface of the cylindrical portion 3c.
And a second tapered surface 3f (or a horizontal surface 3h) are formed,
One type of core body 3 can be used for PVC, polyethylene, and any lining steel pipe 4. In this case, the second tapered surface 3f (or the horizontal surface 3) having the outer diameter of the tubular portion 3c is used.
The h) is formed with a diameter equal to or smaller than the diameter of the polyethylene powder lining steel pipe 4b-1, so that the lining steel pipe 4 can be inserted into the tubular portion 3c in a tightly fitted state.

A seal ring 5 is fitted on the outer peripheral surface of the cylindrical portion 3c of the core body 3. The seal ring 5 of the present embodiment is a wedge-shaped seal ring made of an appropriate polymer material such as NBR, and when the lining steel pipe 4 is connected to the connecting portion 2 of the connected body 1, It is watertightly adhered to the exposed metal portion 4c of the pipe end to prevent corrosion of this portion. The seal ring 5 may have an elliptical cross section, a circular cross section, or any other shape other than the above.
Further, in this case, when the annular concave portion 2b, the annular stepped portion 2c, the edge surface 2e, and the flow passage surface subsequent to the annular concave portion 2b are subjected to grinding processing or the like to provide a processed surface, the adhesion with the core body 3 can be further enhanced.

Next, the operation of the above embodiment will be described.
The core body 3 provided in the connecting portion 2 of the connected body 1 has a ring base portion of the core body 3 in which molten plastic is injected into the annular recess 2b and the annular step portion 2c in the inner part of the connecting portion 2 by an injection molding method. 3a is molded in close contact with the annular recess 2b, and the annular protrusion 3b is molded in close contact with the annular step 2c. At this time, the annular protrusion 3b formed integrally with the annular base 3a of the core body 3 has the sealing surface 2d of the annular step 2c.
Since it is in close contact with the core body 3, high adhesion between the metal forming the main body 1 and the synthetic resin of the core body 3 can be obtained.

In this case, by forming the angle α of the annular step portion 2c formed in the inner part of the connecting portion 2 of the main body 1 to be 90 ° or less, the annular step portion 2c of the connected body 1 and the annular portion of the core body 3 are formed. Since the protrusions 3b come into contact with each other, even if the diameter of the core body 3 is reduced in the centripetal direction when the lining steel pipe 4 is screwed into the connection portion 2, the adhesion between the two is maintained. Also, due to the stress acting on the core body 3 when the lining steel pipe 4 is screwed into the connection portion 2,
The annular protrusion 3b of the core body 3 is the sealing surface 2 of the annular step 2c.
It firmly adheres to d, and a high sealing property is obtained. Furthermore,
With the screwing force of the lining steel pipe 4, the annular step portion 2c
The annular projection 3b of the core body 3 strongly and closely contacts the processed surface of (3) to improve the sealing performance.

As a result, when the male screw portion 4a formed on the pipe end portion of the lining steel pipe 4 is screwed into the female screw portion 2a formed on the connecting portion 2 of the main body 1 and screwed, the lining steel pipe 4 becomes hard vinyl chloride. When the lining layer 4b-2 is thick like a lining steel pipe, the tubular portion 3c of the core body 3
The first tapered surface 3e is reduced in diameter by the lining layer 4b-2 so as to be strongly squeezed in the centripetal direction and is watertightly adhered, so that the inner wall surface of the pipe end is sealed. At this time, since an appropriate elastic force is applied to the tubular portion 3c by the annular groove 3g provided at the rear end portion of the tubular portion 3c of the core body 3, the sealing property of the above-mentioned portion is further improved. Become.

When the lining layer 4b-1 is thin like a polyethylene powder lining steel pipe, the second taper surface 3f or the horizontal surface 3h of the tubular portion 3c of the core body 3 is centered by the lining layer 4b-1. The diameter is slightly reduced and it adheres watertightly to obtain a seal on the inner wall surface of the pipe end.

As described above, the metal exposed portion 4c of the pipe end of the lining steel pipe 4 screwed into the connecting portion 2 of the main body 1 is watertightly sealed by the seal ring 5 provided on the tubular portion 3c of the core main body 3. Since the exposed metal portion 4c at the pipe end of the lining steel pipe 4 does not come into contact with water or warm water, this portion 4
Red rust is not generated in c and red water is not generated.

2 to 4 are other embodiments of the present invention. The embodiment shown in FIG. 2 is basically the same as the first embodiment except that the edge surface of the annular step portion 2c formed in the inner part of the connecting portion 2 is chamfered 2e. By chamfering 2e on the annular step 2c, the injection and injection of the molten plastic at the time of molding the core body 3 can be performed smoothly and uniformly, and the annular base portion 3a and the annular protrusion 3b of the core body 3 can be molded. This can be surely performed, and the adhesion between the core body 3 and the body 1 can be further enhanced.

The embodiment shown in FIG. 3 is an embodiment in which a plurality of, for example, three annular step portions 2c, 2c, 2c are formed in the inner portion of the connecting portion 2. Thereby, the annular base portion 3a of the core body 3 is
When molding, the plurality of annular projections 3b, 3b, 3b are formed in close contact with the sealing surfaces 2d, 2d, 2d of the annular stepped portions 2c, 2c, 2c, so that, compared to the first embodiment, Further, the adhesion between the core body 3 and the body 1 can be enhanced. In addition,
In this embodiment, the chamfers 2e, 2e, 2e are applied to the edges of the annular stepped portions 2c, 2c, 2c, so that the molding of the respective parts 3a, 3b of the core body 3 is surely performed as in the second embodiment. And the adhesion between the core body 3 and the body 1 can be further enhanced.

In the embodiment shown in FIG. 4, instead of the annular step portion 2c, an annular dovetail groove 2f is formed in the inner portion of the annular recess 2b to mold the core body 3. In this embodiment as well, by chamfering 2e as in the other embodiments, it is possible to surely form the respective parts 3a and 3b of the core body 3 and to improve the adhesion between the core body 3 and the body 1. Can be increased.

[0036]

As is apparent from the above description, the pipe end anticorrosion structure of the present invention can exert the following excellent effects. That is, the core body provided in the body of the piping equipment such as the valve and the pipe joint is molded with extremely high adhesion by the joining of the annular step portion and the annular protrusion, so that the space between the body and the core body is There is no gap in. In particular, by setting the angle α of the annular stepped portion to 90 ° or less, even with respect to the shrinkage phenomenon during injection molding or after molding, and the stress in the centripetal direction of the core body during screwing of the lining steel pipe, Since the sealing surface formed on the annular step portion and the annular base portion and the annular protrusion of the core body are firmly adhered to each other, high sealing performance can be obtained regardless of the size of the main body.

Further, the excellent adhesion between the annular stepped portion and the annular protruding portion can prevent a phenomenon such as rattling due to a difference in expansion coefficient between them, so that the nominal diameter of the connected body becomes large. Even in such a case, it is possible to prevent the peeling of the both and the generation of a gap at this portion, and it is possible to reliably exhibit the function of the pipe end anticorrosion structure.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment to which the present invention is applied.

FIG. 2 is a sectional view showing a second embodiment in which an annular step is chamfered.

FIG. 3 is a sectional view showing a third embodiment provided with a plurality of annular step portions.

FIG. 4 is a cross-sectional view showing a fourth embodiment in which a dovetail groove is provided instead of the annular step portion.

FIG. 5 is an enlarged view of a main part showing a close contact state between the main body and the core main body.

FIG. 6 is a cross-sectional view showing a conventional pipe end anticorrosion structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Connected object of piping equipment 2 Connection part 2a Female screw part 2b Annular recessed part 2c Annular step part 2d Seal surface 2e Chamfering 2f Dovetail groove 3 Core body 3a Annular base part 3b Annular protrusion 3c Cylindrical part 5 Seal ring

Claims (5)

[Claims] 1. A pipe end anticorrosion structure integrally formed with a core main body having a tubular portion toward the opening direction of the connecting portion at the connecting position of the connecting body of the piping equipment, wherein the connecting portion of the connecting body is connected. An annular recess is formed on the inner side, an annular step is formed further on the inner side of the annular recess, and when the core body is insert-molded at the connection position of the connected body, the annular recess is A pipe end anticorrosion structure characterized in that an annular base portion provided on a core main body and an annular projection formed on the core main body are formed in a close contact with the annular step portion. 2. The pipe end anticorrosion structure according to claim 1, wherein the angle α of the annular step portion is 90 ° or less. 3. The pipe end anticorrosion structure according to claim 1, wherein the annular step portion is provided in a plurality of steps. 4. The pipe end anticorrosion structure according to any one of claims 1 to 3, wherein a chamfering process is applied to an edge surface of the annular step portion on the flow path side. 5. The outer peripheral surface of the cylindrical portion of the core body,
The pipe end anticorrosion structure according to any one of claims 1 to 4, wherein a seal ring having an appropriate cross-sectional shape such as a wedge-shaped cross section, an elliptical cross section, a circular cross section, and a triangular cross section made of an appropriate polymer material is attached.