JPS6111598Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a pipe end structure of an internally coated steel pipe.

(Prior Art) Conventionally, when connecting internally coated steel pipes, in order to prevent corrosion of the pipe end surfaces, for example, as described in Japanese Patent Publication No. 16344/1983, the connecting ends of the steel pipes are coated with a synthetic resin coating. There is a method in which a bituminous sealing material or adhesive is applied to the cap, and then an annular cap with a substantially U-shaped cross section is fitted.

(Problem that the invention aims to solve) However, in this case, a sealing material or adhesive is applied to the gap between the connecting end of the steel pipe and the cap, and the cap is fixed only by this adhesive force, so the fixing force is not necessarily sufficient. Moreover, if the connection end of the steel pipe was attached to a socket etc. before the adhesive had dried, the cap would fall off.

(Means for Solving the Problems) The pipe end structure of the inner-coated steel pipe according to the present invention has a flange at one end of the short pipe within the pipe end of the inner-coated steel pipe whose inner surface is provided with a synthetic resin layer. The short tube is provided with at least one of concave portions and convex portions on the outer surface thereof, and an anticorrosive adhesive containing a liquid substance that swells or dissolves the synthetic resin layer is provided around at least the concave portions and convex portions of the outer surface. The coated flanged short tube is inserted, and at least the synthetic resin layer of the inner-coated steel tube bulges into the recess of the flanged short tube, or the convexity of the flanged short tube is caused to bulge out into the melted synthetic resin layer of the inner-coated steel tube. This is caused by the part being wedged in.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

Reference numeral 1 designates an inner-coated steel pipe, and a synthetic resin layer 12 made of vinyl chloride resin or the like is provided on the inner surface of the steel pipe 11, and a male threaded portion 13 is provided on the outer peripheral surface of the end of the pipe.

2 is a short pipe with a flange made of corrosion-resistant material;
As shown in the figure, a flange 22 is provided at one end of the short tube 21, and a groove 211 is provided along the circumferential direction at one end of the outer surface of the short tube 21 adjacent to the flange 22. A protrusion 212 is provided along the circumferential direction on the outer surface of the other end, and both side surfaces of the protrusion 212 are
The side surface 214 on the side of the groove 211 is a steep slope, and the side surface 213 on the opposite side from the side where the groove 211 of the short pipe 21 is provided is in the opposite direction from the side where the groove 211 of the short pipe 21 is provided. It is a gently sloped surface that gradually becomes smaller in diameter toward the end.

Note that the minimum outer diameter of the groove 211 is slightly smaller than the inner diameter of the inner-coated steel pipe 1, and the maximum outer diameter of the protrusion 212 is slightly larger than the inner diameter of the inner-coated steel pipe 1.

Further, the tube wall of the short pipe 21 has a notch 23 extending from one end where the groove 211 is not provided to the end where the groove 211 is provided, that is, in the direction of the collar 22.
is provided so that the flanged short tube 2 can be easily inserted and fitted into the tube end of the internally coated steel tube 1.

3 is an anti-corrosion adhesive layer, and as an anti-corrosion adhesive, for example, the inner surface of the steel pipe 1 is coated with polyester resin.
A liquid substance that swells or dissolves the synthetic resin layer 12, for example, if the synthetic resin layer is made of vinyl chloride resin, acetone, methyl ethyl ketone,
It is formed by applying and drying a material containing approximately 4 wt% of ketones such as cyclohexane, esters such as acetate, dichloroethane, etc. In this case, the flanged short tube is made of, for example, polyethylene, which is soaked in the above-mentioned liquid substance. When an anticorrosive agent is applied around the concave grooves 211 and the protrusions 212 of the flanged short tube 2 and the flanged short tube 2 is inserted into the tube end of the inner-coated steel tube 1, the synthetic resin of the inner-coated steel tube 1 is removed. The layer 12 is swollen or softened by the liquid substance that swells or dissolves the synthetic resin layer contained in the anticorrosive adhesive, and the inner-coated steel pipe 1 is formed in the groove 211 of the flanged short pipe 2. Either the resin layer 12 swells and the protrusions 212 of the flanged short pipe 2 bite into the synthetic resin layer 12 of the inner-coated steel pipe 1 (see Figure 1), or only the former (see Figure 2), or In the latter case only (see FIG. 3), the pipe end of the internally coated steel pipe is formed.

In addition, in the above embodiment, the flanged short pipe 2 is the short pipe 21.
Although the short pipe has been described as having grooves 211 and protrusions 212 on its outer surface, the present invention is not limited to this, and the short pipe may have at least either a recess or a protrusion on its outer surface. In this case, at least the synthetic resin layer of the inner-coated steel pipe is bulged into the recessed part of the short flanged pipe, or the convex part of the short flanged pipe is bitten into the synthetic resin layer of the inner-coated steel pipe. Bye.

(Effect of the invention) As described above, the pipe end structure of the inner-coated steel pipe according to the present invention has anti-corrosion properties that include a liquid substance in the end of the inner-coated steel pipe that swells or dissolves the synthetic resin layer on the inner surface. A flanged short tube having at least one of a concave portion and a convex portion on the outer surface of the short tube is inserted through an adhesive, and a synthetic resin layer of the inner-coated steel tube is inserted into at least the concave portion of the flanged short tube. is bulged out or the convex part of the flanged short tube is dug into the melted synthetic resin layer of the inner-coated steel tube, so that the surface of the flanged short tube and the inner surface of the inner-coated steel tube and the flanged short tube are The irregularities interlock with each other through the anti-corrosion adhesive layer, and together with the adhesive strength of the anti-corrosion adhesive layer, the flanged short pipe is firmly fixed to the end of the internally coated steel pipe and will not come off.
Furthermore, the anticorrosive adhesive layer protects the end of the inner-coated steel pipe, and when the inner-coated steel pipe is connected to a pipe joint or the like, the end of the inner-coated steel pipe can be protected from corrosion.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing one embodiment of the invention, Figs. 2 and 3 are partially cutaway front views showing another embodiment of the invention, and Fig. 4 is a partially cutaway front view showing another embodiment of the invention. FIG. 2 is a partially cutaway front view showing an example of a flanged short tube to be used. 1...Inner coated steel pipe, 2...Short pipe with flange, 3...
Anticorrosive adhesive layer, 11... Steel pipe, 12... Synthetic resin layer, 21... Short pipe, 22... Flange, 211... Concave groove, 212... Convex strip.

Claims (1)

[Scope of utility model registration request] A flange is provided at one end of the short tube in an inner-coated steel tube whose inner surface is provided with a synthetic resin layer, and at least one of a concave portion and a convex portion is provided on the outer surface of the short tube. A flanged short tube coated with an anticorrosive adhesive containing a liquid substance that swells or dissolves the synthetic resin layer is inserted around the concave portion and convex portion, and an inner-coated steel tube is formed in at least the concave portion of the flanged short tube. A pipe end structure of an inner-coated steel pipe in which the resin layer is bulged or the convex part of the flanged short pipe is bitten into the melted synthetic resin layer of the inner-coated steel pipe.