JPS5827179Y2 - Joints of internally coated steel pipes - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a connection section for internally coated steel pipes.

When connecting internally coated steel pipes, it is necessary to protect the end faces of the pipes from corrosion and prevent liquid leakage from the joints.

Conventionally, for example, in a joint for an internally coated steel pipe that is screwed in with a tapered screw with a joint pipe interposed, as in Japanese Utility Model Publication No. 45-17969, an L-shaped joint that is closely connected to the internally coated steel pipe from the end surface to the inner surface of the pipe has been proposed. A coating ring made of a heat-resistant or anti-corrosion metal thin plate with a shaped cross section is adhered with a heat-resistant or anti-corrosion adhesive, and the outer diameter of the coating ring is set to the diameter of the thread root of the basic diameter of the inner-coated steel pipe to produce an inner-coated steel pipe. A structure has been proposed in which a covering ring is bonded at the outer periphery between the thread of the joint pipe and the thread of the joint pipe.

However, during the repeated use of hot water supply and water supply, a gap develops between the pipe end face and the covering ring.
There were disadvantages in that it was not possible to sufficiently protect the pipe end surface from corrosion, and liquid leakage occurred from the joints.

The present invention has been made with the aim of eliminating the conventional drawbacks as mentioned above, and its gist is that a male threaded portion is provided on the outer circumferential surface of the pipe end of an internally coated steel pipe, and the male threaded portion is At the connection part screwed into the female thread part of the joint, so as to cover the end surface of the internally coated steel pipe and the inner circumferential surface of the pipe end,
It exists in a connecting part of an inner-coated steel pipe in which a flanged short pipe made of a resin pipe that has been softened by heating and is given the property of shrinking and solidifying and expanding its diameter under heat is abutted.

Hereinafter, the present invention will be explained with reference to embodiments of the drawings.

Reference numeral 1 denotes an inner-coated steel pipe, in which a coating layer 12 made of thermoplastic resin or the like is provided on the inner surface of the steel pipe 11, and a tapered male threaded portion 13 is provided on the outer peripheral surface of the pipe end.

Reference numeral 2 denotes a pipe joint, and a tapered acid threaded portion 21 is provided on the inner circumferential surface of the end thereof.

Reference numeral 3 designates a flanged short tube that has the property of expanding in diameter under heating. A collar 31 having approximately the same outer diameter is provided.

The flanged short tube 3 is given the property of expanding in diameter under heating.
It is applied by cooling and solidifying this as it is.

For example, although not shown in the drawings, a mold with a large diameter part, a small diameter part, and a mold whose diameter gradually decreases from the large diameter part to the small diameter part is used on the inner peripheral surface of the cylindrical body. A chlorinated vinyl chloride resin pipe softened by heating at ~140'C is pushed into the mold from the large diameter part to the small diameter part, and after being left to cool, it is removed from the mold, and this pipe is made into a short flanged pipe. It is manufactured by a method such as cutting into a shape.

Since this flanged short tube 3 is solidified while being reduced in diameter in the radial direction, it has the property of expanding in diameter under heating.

The flanged short tube 3 is brought into contact with the inner surface of the inner-coated steel tube 1 so as to cover the end surface on which the tapered acid threaded portion 13 is provided and the inner curved surface of the tube end (see FIG. 1).

In order to prevent the flanged short pipe 3 from being pulled out, a protrusion 321 is provided along the circumferential direction on the outer peripheral surface of the short pipe 32. It may be fitted into a cutout 121 (see FIG. 3).

With the flanged short pipe 3 in contact with the end surface of the internally coated steel pipe 1 and the inner peripheral surface of the pipe end, the tapered acid threaded portion 13 of the pipe end is connected to the tapered acid threaded portion of the pipe fitting 2. 21 and tighten.

After that, when immersed in hot water at 100°C for 24 hours, the short pipe 32 of the flanged short pipe 3 expands in diameter and comes into close contact with the inner peripheral surface of the end of the internally coated steel pipe 1, and the collar 31 also expands in diameter to form a pipe joint. Its outer peripheral surface is in close contact with the tapered acid threaded portion 21 of the internally coated steel pipe 1, preventing water from penetrating into the end face of the internally coated steel pipe 1 and preventing corrosion of the end face. The structure prevents water from entering, prevents corrosion of the threaded part, and prevents water from leaking from the threaded part (see Figure 2).

In addition, even if you do not go to the trouble of using the immersion heating method as mentioned above,
A similar structure can be created by heating during hot water supply.
Moreover, in this case, it can be made more perfect with the passage of time.

As mentioned above, in the connection part of the inner-coated steel pipe of the present invention, the end face of the inner-coated steel pipe and the inner circumferential surface of the pipe end are connected at the connection part where the male threaded part of the inner-coated steel pipe is screwed into the female threaded part of the pipe joint. A flanged short tube made of a resin tube that is made of a resin tube that has been given the property of shrinking and solidifying the diameter of the softened resin tube and expanding its diameter under heating is in contact so as to cover the flange. The short pipe and collar of the pipe expand in diameter to the inner circumferential surface of the pipe end of the internally coated steel pipe and the pipe fitting. ◎The short pipe and collar part of the pipe are in close contact with the inner peripheral surface of the pipe end of the internally coated steel pipe and the pipe fitting. ◎The short pipe and the collar part of the pipe are in close contact with the end face of the internally coated steel pipe, the male thread of the internally coated steel pipe, and the female thread of the pipe fitting. It is possible to prevent corrosion by shielding the threaded part of the pipe from running water in the pipe for a long period of time, and also to prevent water leakage from the connection part.

[Brief explanation of drawings]

Fig. 1 is a partially cutaway front view showing an embodiment of the present invention;
This figure is a partially cutaway front view showing the flanged short tube of the embodiment shown in FIG. 1 in an enlarged diameter state, and FIG. 3 is a partially cutaway front view showing another embodiment of the present invention. Explanation of symbols, 1... Internally coated steel pipe, 2...
...Pipe fitting, 3...Short pipe with flange, 13...
・Tapered acid thread part, 21...Tapered acid thread part.

Claims (1)

[Scope of utility model registration request] A male thread is provided on the outer peripheral surface of the end of the internally coated steel pipe, and the male thread is screwed into the female thread of the pipe joint to cover the end surface of the internally coated steel pipe and the inner peripheral surface of the pipe end. A connecting portion of an inner-coated steel pipe in which a flanged short pipe made of a resin pipe which has been softened by heating, is reduced in diameter and solidified, and is made of a resin pipe which has the property of expanding its diameter under heating is brought into contact with the resin pipe.