JPH02138596A - Corrosistant pipe joint - Google Patents

Abstract

PURPOSE:To improve the workability and prevent the occurrence of peeling and cracking of a coat by injection molding a coating material on a pipe joint body made of metal having uneven parts such as protrusions, recessed parts and grooves on at least either the inner surface or the outer surface. CONSTITUTION:A coating material is injection-molded on a metal pipe joint body 2 having protrusions, recessed parts, and grooves of forms such that a coating material layer 1 lined or coated at least either the inner surface or the outer surface is engaged to and not easily separated from the pipe joint body, for example, a protruded part 3 and a recessed part 4, to form a corrosistant pipe joint. As the coating material layer 1 formed on such uneven surface is fixed in the state engaging with the pipe joint body 2, it dose not easily cause peeling and cracking.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a corrosion-resistant pipe joint.

[Conventional technology]

Conventionally, rubber products (
Technology has been widely adopted in which the inner and outer surfaces of pipes and fittings are coated with lining or coating materials such as elastomer or plastic. Many of these techniques involve applying paint or adhering films, sheets, and other molded products; however, shrinkage of the formed coating may cause peeling or gaps from the metal body on the inner surface. , cracks may occur on the outer surface,
It will no longer be able to fulfill its anti-corrosion role. In addition, when applying the method using adhesive to the inner and outer surfaces of the socket, for example, the fourth
Resin layer 1 as shown in Figure (inner surface) and Figure 5 (outer surface).
and the pipe joint body 2 are fixed with the adhesive layer 6.

The adhesive used at this time is a reaction-curing resin or a heat-sensitive (hot melt) resin, and in a processing method commonly called attomer processing, a powdered adhesive is applied to a pipe joint heated to 120 to 200"C. A process is adopted in which the bolybdenum-based coating and the malleable cast iron surface are bonded together by sprinkling.

Therefore, such a method generally has poor workability and increases costs, so it cannot be said to be a preferable method.

[Problem to be solved by the invention]

As described above, the problem with conventional techniques is that it is not possible to obtain a corrosion-resistant pipe joint that has good lining or coating workability, does not cause peeling or cracking of the resulting coating, and is extremely cost-effective. The challenge was to solve this problem.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides that coating material layers to be lined or coated are fitted together on at least one of the inner or outer surfaces so that the covering material layers can be easily coated or lined with each other. 1
This is a corrosion-resistant pipe joint in which a covering material is injection molded onto a metal pipe joint body that is provided with projections, depressions, grooves, and other irregularities that cannot be removed.

[Example] First, the metal pipe joint according to the present invention may be an elbow type, a cheese type, a socket type, or a bent type, and the covering material to be lined or coated may be either plastic or elastomer. It is not particularly limited.

Next, in the present invention, irregularities such as protrusions, depressions, grooves, etc. that are fitted into each other and cannot be easily separated are not particularly limited, but for example, the tips are curved,
It is a suitable combination of thickened protrusions, undercut-like depressions, or grooves, and is an uneven structure consisting of convex portions 3 and concave portions 4 as illustrated in FIGS. 1, 2, and 3. The coating material layer 1 formed on these uneven surfaces is fitted into the pipe joint body 2 and firmly fixed, so that it does not easily peel off or crack. Further, as illustrated in FIGS. 1 and 2, a cylindrical tube end core portion 5 facing the female threaded portion is also provided.
(Although an example in which the outer surface is parallel to the threaded portion is shown in the figure, a tapered surface may also be provided) is preferably provided and connected to the inner surface covering material of the male threaded pipe (not shown) to be inserted. Here, the tube end core portion 5 may be formed integrally with the coating material layer 1 as shown, or may be formed by screwing a separately formed cylindrical molded body as a modification of FIG. 2. In the outer sheathing material layer, as illustrated in FIG. 3, the tube end portion can be protruded and brought into close contact with the outer sheathing material (not shown) of the male threaded pipe to be inserted. .

In addition, in order to further enhance the effect that the coating material N1 does not peel off from the pipe fitting body 2, it is desirable that the inner surface roughness of the pipe fitting body 2 is 20s or more in the case of an inner surface coating, and in the case of an outer surface coating. The outer surface roughness of the pipe fitting body 2 is 40s.
It is preferable that it is above.

Conventional anti-corrosion pipe joints with internal coatings, as shown in Figure 4, usually show peeling phenomenon after 2 to 3 days, but the first
In the pipe joint of the present invention as shown in the figure, such a phenomenon is not observed even after 2 to 3 months, and furthermore, in the case of the conventional outer surface coating as shown in Fig. Although cracking or peeling was observed, such phenomena were not observed at all in the pipe joint of the present invention as shown in FIG.

〔effect〕

The corrosion-resistant pipe joint of the present invention has a coating layer formed on at least one of the inner or outer surfaces of the pipe joint body by providing grooves or grooves such as protrusions or undercuts. can be dispersed and absorbed to prevent peeling or falling off from the inner surface of the pipe joint.The unevenness also plays a similar role in preventing shrinkage of the outer covering material.
Extremely effective in preventing cracks (improving stress cranking resistance). Furthermore, since no adhesive is required, the workability is good, so the significance of this invention can be said to be extremely large.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are longitudinal cross-sectional views of main parts to illustrate the structure of the present invention, and FIGS. 4 and 5 are longitudinal cross-sectional views of main parts to illustrate the structure of a conventional product. be. DESCRIPTION OF SYMBOLS 1...Coating material layer, 2...Pipe joint body, 3...Protrusion, 4...
- Concave portion, 5...Tube end core portion.

Claims (1)

[Claims] (1) A metal pipe joint that has projections, depressions, grooves, or other irregularities on at least one of its inner or outer surfaces in which the lining or coating layer is fitted into each other and cannot be easily removed. A corrosion-resistant pipe fitting characterized by having a coating material injection molded onto the main body.