JP2001146987A - Pipe end anticorrosive joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To positively achieve a predetermined pipe end anticorrosive ability by easily and strongly adhesively fixing a core and a joint body while using a polyethylene resin core having no fear of generating dioxin. SOLUTION: An annular end face 22a of a collar part 22 of the polyethylene resin core 2 is modifyingly processed into an easily adhesive surface by projection of a plasma jet and an epoxy system adhesive 9 is built up for coating to a crossing part of the modifyingly processed annular end face 22a of the collar part 22 and a resin lining layer 3 coated on a recessed portion 12 without as screw of the joint body 1 for integrally adhering the joint body 1 and the polyethylene resin core 2. By this, this joint is constituted so that water is prevented form penetrating into an axial direction end face 44 of a steel pipe 41 from a connecting portion of the core 2 and the joint body 1.

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 joint used for a water supply or hot water supply piping system.

[0002]

2. Description of the Related Art In a general pipe system of this kind, in order to prevent deterioration of water quality such as generation of red water due to rust at an inner surface of a pipe tube or a connection point, an inner surface of a steel pipe is used as a pipe body. An inner surface coated steel pipe covered with a synthetic resin lining layer is used, and a pipe end anticorrosion joint is used at a connection point.

[0003] Conventional pipe end anticorrosion joints are:
For example, as disclosed in Japanese Utility Model Publication No. 2-1582 and as shown in FIG. 8, as shown in FIG. 8, external thread portions 43 formed on the outer periphery of the inner surface coated steel pipe 4 at both ends in the axial direction.
A joint body 1 having an internal threaded portion 11, 11 into which a resin lining layer 3 such as epoxy is coated and formed in a threadless concave portion 12 between the internal threaded portion 11, 11; An annular flange 22 is continuously provided at an end of a cylindrical body 21 inserted and inserted into an end of the inner surface coated steel pipe 4, and an outer periphery of the flange 22 is provided on an inner thread 11 of the joint body 1. An external screw portion 23 to be screwed is formed, and an annular lip portion 24a protruding outward from the cylindrical body portion 21.
And a resin core 2 provided with a seal portion 24 for sealing by an annular groove portion 24b formed adjacent thereto and having its lip portion 24a elastically pressed against the inner surface coating layer 42 of the steel pipe 4. Is provided.

[0004] Then, threaded portions 11 at both ends of the joint body 1 are provided.
The outer thread 23 of the flange 22 of the resin core 2 is screwed to the resin core 2, and the annular end face 22 a of the flange 22 is
After screwing the core 2 into the joint body 1 until it comes into contact with the end of the joint body 1, the outer threaded portion 43 at the end of the inner surface coated steel pipe 4 is screwed into the inner threaded portions 11 at both ends of the joint body 1. The lip portion 24a of the seal portion 24 provided on the cylindrical body portion 21 of the core 2 is elastically pressed against the inner surface coating layer 42 of the steel pipe 4, and at the pressed portion, the sealing property (watertightness) of the connection portion is made. As a result, the internal flow paths of the inner coated steel pipes 4 and 4 screwed to both ends of the joint main body 1 are connected to each other through the internal passages of the cores 2 and 2.

[0005]

By the way, in the conventional pipe end anticorrosion joint having the above structure, the inner surface coated steel pipe
Axial end surface 44 of steel pipe 41 and external thread portion 43
In order to ensure the anti-corrosion performance of the
A high sealing property is required at a contact point between the annular end face 22a of the flange 22 and the end of the resin lining layer 3 of the joint body 1. However, the annular end surface 2 of the flange portion 22 of the resin core 2 is merely used.
It is very difficult to ensure high sealing performance with a configuration in which only the end 2a and the end of the resin lining layer 3 of the joint body 1 are brought into contact with each other. Water penetrates into the screwed portion with the portion 23, and the water passes through the screwed portion and comes into contact with the axial end face 44 of the steel pipe 41 and corrodes, so that a predetermined pipe end corrosion protection performance can be obtained. Can not.

As a countermeasure, a flange 22 of the resin core 2 is provided.
The core 2 and the joint body 1 can be bonded and fixed by, for example, overlaying a two-component type epoxy-based adhesive on the intersection of the annular end face 22a and the end of the resin lining layer 3 of the joint body 1. Conceivable.

On the other hand, vinyl chloride resin, which has been conventionally used as a material for this type of joint, may generate dioxin and the like due to slight errors in combustion conditions during waste material treatment or combustion for recycling. Therefore, it is desirable to use a polyethylene resin as the material of the resin core instead of the vinyl chloride resin.

However, when using a core made of polyethylene resin, it is very difficult to bond the core to the joint body, unlike when using a core made of vinyl chloride resin. That is, the two cannot be firmly bonded and fixed, resulting in poor bonding or insufficient bonding force, so that a predetermined sealing property cannot be ensured and also that the sealing portion 24 cannot be secured.
The lip portion 24a is elastically pressed against the inner coating layer 42 of the steel pipe 4, so that when the steel pipe 4 is screwed and connected to the joint body 1, the core 2 rotates together and the overlay is applied to the bent intersection. There is a problem that the adhered adhesive comes off, the sealing property is further reduced, and a predetermined pipe end anticorrosion performance cannot be achieved.

The present invention has been made in view of the above-mentioned circumstances, and uses a polyethylene resin core which is unlikely to generate dioxin or the like, and easily and strongly adheres and fixes the core and the joint body to a predetermined position. It is an object of the present invention to provide a pipe end anticorrosion joint capable of reliably achieving pipe end anticorrosion performance.

[0010]

In order to achieve the above object, a pipe end anticorrosion joint according to the present invention has an internally threaded portion to which an end of an inner surface coated steel pipe is screwed, and a threadless portion. The joint body is formed by coating a resin lining layer, and an annular flange is connected to the end of a cylindrical body inserted into the end of the steel pipe, and the outer periphery of the flange is Is a polyethylene resin provided with an outer thread portion screwed into the inner thread portion of the joint body, and a seal portion elastically pressed against the inner surface coating layer of the steel pipe on the cylindrical body portion. Pipe end corrosion-resistant joint comprising a core made of, and the surface of the annular end face is modified by projecting a plasma jet toward the annular end face of the flange portion of the polyethylene resin core, The annular end face of the modified flange and the joint body And it is characterized in that it is adhered and fixed together with the fitting body and the core adhesive is applied to the intersection of the fat lining layer.

According to the pipe end anticorrosion joint of the present invention having the above-described structure, it is possible to prevent the generation of dioxin and the like at the time of waste material treatment and combustion for recycling by using a polyethylene resin core. In addition, since the surface of the annular end face is modified by projecting a plasma jet onto the annular end face of the flange portion of the polyethylene resin core, the polyethylene core and the resin of the joint body are modified. The lining layer can be easily and strongly adhered and fixed by applying an epoxy adhesive.
As a result, the sealing property of the contact point between the annular end surface of the flange portion of the core and the end portion of the resin lining layer of the joint body is ensured, and the core co-rotates when the inner surface coated steel pipe is screwed to the joint body. The adhesive is not peeled off, the sealability by the adhesive is maintained even when the joint is assembled, and a predetermined pipe end corrosion preventing performance can be secured.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway longitudinal sectional view showing an assembled state of a pipe end anticorrosion joint of the present invention. In FIG. 1, the same members as those of the conventional pipe end anticorrosion joint shown in FIG. I will explain.

The joint body 1 is a socket type having tapered internal thread portions 11, 11 engraved at both ends in the axial direction thereof, and a threadless concave portion 12 between the internal thread portions 11, 11. The resin lining layer 3 such as epoxy is formed on the concave portion 12 having no screw. As shown in FIG. 2, the lining layer 3 includes not only the concave portion 12 having no screw but also the concave portion 12 having no screw and the inner thread portion 11 of the inner thread portions 11 on both sides thereof.
It is formed so as to extend to a and 11a.

The core 2 is made of polyethylene resin, and an annular flange 22 is integrally connected to an end of a cylindrical body 21 inserted and inserted into an end of the inner surface coated steel pipe 4. The inner thread portion 1 of the joint body 1 is provided on the outer periphery of the flange portion 22.
1 and a tapered outer thread portion 23 which is screwed into the cylindrical body 21 is formed at an intermediate portion in the axial direction of the cylindrical body portion 21 so as to protrude outward from the body portion 21 and as shown in FIG. An annular lip portion 24 formed to be inclined in the direction of the flange portion 22 side.
a, an annular groove 24b formed adjacent to the inside of the lip 24a, and O fitted into the annular groove 24b.
The seal portion 24 is formed of a ring 24 c, and the lip portion 24 a elastically presses against the inner coating layer 42 of the steel pipe 4 to seal between the core 2 and the inner coating steel pipe 4.

The flange 22 of the polyethylene resin core 2
The annular end face 22a has been subjected to a modification process for converting the molecular structure of the surface into an easily adhesive property by a plasma jet projected toward the annular end face 22a at a time before the joint is assembled. I have. This modification processing is limited to the very surface layer of the annular end face 22a in the polyethylene resin core 2, and does not change the properties and strength of the core 2. For example, the following method is adopted as the surface modification processing means for the easy adhesion.

That is, as shown in FIG. 4, the polyethylene resin core 2 is placed on the belt conveyor 6 with the annular end surface 22a of its flange 22 facing upward, and the arrow X
A plasma processing apparatus 8 that ejects the plasma jet 7 downward is provided above the transport path while transporting the plasma jet 7 downward. The plasma processing apparatus 8 has a water repellency by generating and projecting a gas flow containing a chemically active excited species, that is, a plasma jet 7 using corona discharge generated in the atmosphere. The surface of the annular end surface 22a of the polyethylene resin core 2 is modified to be hydrophilic and the surface is modified to impart wettability.

If the polyethylene resin core 2 to be modified has a small diameter, the plasma processing apparatus 8
On the side, as shown in FIG. 5, a single torch 8a having a width L1 slightly larger than the outer diameter D1 of the core 2 is provided, and the projection range L (==) of the plasma jet 7 by this single torch 8a is provided.
The surface of the annular end face 22a is reformed by transporting the core 2 in the direction of the arrow X through the belt conveyor 6 so that the flange end face 22a passes through L1). When the polyethylene resin core 2 has a large diameter, as shown in FIG. 6, the outer diameter D2 of the core 2 is slightly smaller than the radial width W2 of the annular end face 22a on the plasma processing apparatus 8 side. A plurality (three) of torches 8a having a large L2 are arranged so as to be shifted in the core transport direction X, and the flange annular end face 22a passes through the projection range L of the plasma jet 7 by the plurality of torches 8a. Belt conveyor 6
The surface of the annular end face 22a is reformed by transporting the core 2 in the direction of the arrow X through.

As shown in FIG. 7, instead of the belt conveyor 6, a polyethylene resin core 2 is placed on a rotary table (not shown) and an annular end face 22a of a flange 22 thereof.
The plasma jet 7 is projected from a single torch 8a on the plasma processing apparatus 8 side while the core 2 is rotated around its axis via a rotary table. A reforming process may be performed.

The outer thread 23 of the flange 22 of the polyethylene resin core 2 which has been modified in advance to convert the molecular structure of the surface into an easy-adhesive property by the above-described method is connected to the inner thread of the joint body 1 at both ends. The core 2 is screwed into the joint body 1 until the annular end surface 22a of the flange 22 comes into contact with the end of the resin lining layer 3 on the joint body 1 side. An epoxy adhesive 9 is applied to the intersection of the annular end surface 22a of the joint body 1 and the resin lining layer 3 of the joint body 1 as shown in FIG. Annular end face 2
Since the molecular structure of the surface of 2a is converted to easy adhesion, the core 2 and the joint body 1 can be easily and strongly adhered and fixed with the epoxy-based adhesive 9, and the sealing property of the connection portion is secured. Both can be integrated with each other.

Thereafter, the internal thread portions 11 at both ends of the joint body 1 are provided.
11 is screwed with an external thread 43 at the end of the inner tube 4 so that the lip portion 24a of the seal portion 24 provided on the cylindrical body 21 of the core 2 has an inner coating layer 42 of the steel tube 4. It is possible to assemble a joint that is elastically pressed against the inner surface of the steel pipe 4 in a state where the press-contacted portion also secures the sealing property (watertightness) of the connecting portion between the inner coated steel pipe 4 and the core 2. The core 2 is also connected to the joint body 1 by screwing.
And the joint body 1 are strongly bonded and fixed via the epoxy adhesive 9, so that the core 2 rotates together and the adhesive 9
There is no possibility that the core 2 and the joint main body 1 are separated from each other, and the sealing property at the connection point between the core 2 and the joint body 1 can be maintained as it is.

Therefore, in the state where the joint is assembled, water penetrates into the axial end face 44 of the steel pipe 41 from any of the connection points between the core 2 and the joint body 1 and the connection points between the inner coated steel pipe 4 and the core 2. There is no danger that rust will be generated, and the predetermined pipe end corrosion protection performance can be reliably exhibited. In addition, the use of the polyethylene resin core 2 reduces the generation of dioxin and the like during waste material treatment and combustion for recycling. It is possible to prevent.

[0022]

As described above, according to the present invention, when dioxin is used for waste material treatment and combustion for recycling, as in the case of using vinyl chloride resin by using polyethylene resin as the material of the resin core, Can be prevented. In addition, the annular end surface of the flange portion of the polyethylene resin core is modified by projecting the plasma jet so that its surface molecular structure is converted to easy adhesion, so that the polyethylene resin core and the resin of the joint body are modified. Even if a general-purpose epoxy adhesive is used, the lining layer can be easily and strongly adhered and fixed, so that the seal between the annular end surface of the core flange and the end of the resin lining layer of the joint body can be sealed. In addition to ensuring the sealability, the adhesive does not peel off due to the co-rotation of the core when the inner surface coated steel pipe is threadedly connected to the joint body, and the sealability with the adhesive is maintained even when the joint is assembled, and the predetermined pipe end is maintained. This has the effect that the anticorrosion performance can be reliably achieved.

[Brief description of the drawings]

FIG. 1 is a partially cutaway longitudinal sectional view showing an assembled state of a pipe end anticorrosion joint according to an embodiment of the present invention.

FIG. 2 is an enlarged vertical sectional view of a main part of FIG.

FIG. 3 is an enlarged vertical sectional view of a main part of FIG. 2;

FIG. 4 is a side view for explaining an example of surface modification processing means for an annular end surface of a flange portion of a polyethylene resin core in the pipe end anticorrosion joint.

FIG. 5 is a schematic plan view illustrating a projection method of a surface-modifying plasma jet when the polyethylene resin core has a small diameter in the surface modifying unit.

FIG. 6 is a schematic plan view illustrating a projection method of a surface-modifying plasma jet when the polyethylene resin core has a large diameter in the surface modifying unit.

FIG. 7 is a schematic plan view for explaining another example of surface modification processing means for an annular end surface of a flange portion of a polyethylene resin core.

FIG. 8 is an enlarged longitudinal sectional view of a main part showing an assembled state of a conventional pipe end anticorrosion joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Joint main body 11 Inner thread part 12 Unthreaded recess part 2 Polyethylene resin core 21 Cylindrical trunk part 22 Flange part 22a Annular end face 23 Outer thread part 24 Seal part 3 Resin lining layer 4 Inner surface coated steel pipe 41 Steel pipe 42 Inner surface coating layer 7 Plasma jet 8 Plasma processing device 9 Epoxy adhesive

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Okamura, Inventor 2-12-1, Morigo-cho, Takaoka-shi, Toyama FK term (reference) 3K01 JA04

Claims (1)

[Claims] 1. A joint body having an inner threaded portion to which an end of an inner surface coated steel pipe is screwed, and a threadless portion coated with a resin lining layer, and inserted into an end of the steel pipe. An annular flange is continuously provided at an end of the cylindrical body, and an outer thread portion screwed to an inner thread portion of the joint body is provided on an outer periphery of the flange portion, and A pipe end anticorrosion joint comprising: a cylindrical body portion; and a polyethylene resin core provided with a seal portion elastically pressed against the inner surface coating layer of the steel pipe. The surface of the annular end surface is modified by projecting a plasma jet toward the annular end surface of the flange, and the intersection between the modified annular end surface of the flange and the resin lining layer of the joint body is performed. Apply adhesive to the part to unite the joint body and core Pipe end anticorrosion joint, characterized in that they are wearing fixed.