JPH0210876Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a pipe joint for connecting internally coated steel pipes.

(Prior art and its disadvantages) Conventionally, when connecting internally coated steel pipes, in order to prevent corrosion on the pipe end surface and to prevent liquid leakage from the joint, for example, as in Utility Model Publication No. 58-32069, the inside of the open end was A short cylindrical body is attached to the jetty of the pipe fitting main body, which has a female thread on the peripheral surface, a concave groove along the circumferential direction on the deep inner peripheral surface, and a jetty along the circumferential direction on the deep part. A pipe joint has been proposed in which one end of the short cylinder is brought into contact with the pipe joint body, and an annular packing is installed between the short cylinder and the pipe joint main body.

However, in the above-mentioned pipe fitting, if the threading accuracy of the external thread of the internally coated steel pipe connected to the pipe fitting is poor and the thread is cut into a long thread, or if the internally coated steel pipe is screwed in too much, The annular packing installed between the cylinder and the pipe fitting body is subjected to excessive compressive force, and the elastic repulsive force acts on the coating layer of the inner-coated steel pipe, causing the coating layer on the end face of the steel pipe to peel off or curl up. There was a drawback of doing so. In addition, the coating layer is locally thickened at the end face and fixed between it and the outer circumferential surface of the short cylinder, and for example, when heating and cooling are repeated, expansion and contraction of the coating layer in the tube axis direction is restricted. As a result, there was a risk that the coating layer would peel off near the connection and the pipe would become clogged.

In an attempt to eliminate this drawback, Japanese Utility Model Application Publication No. 55-140887 discloses a method in which the inner peripheral edge on the open end side of the pipe joint body is formed into an inclined surface between the short cylinder and the pipe joint body. Pipe fittings equipped with annular packing have been proposed, but in the case of such pipe fittings, as shown by the broken line A curve in Fig. 5, the threaded length of the internally coated steel pipe is 15 mm or more, and the threading length is too long. Then, the pressing force applied to the coating layer on the end face of the inner-coated steel pipe is the load that the coating layer can tolerate (approximately 100 to 200 kg/
cm ² ), peeling and peeling of the coating layer occurred, and the effect was not sufficient. Here, FIG. 5 is a curve diagram showing the relationship between the threaded length of the internally coated steel pipe and the pressing force on the end face of the internally coated steel pipe.

(Purpose) In view of the above-mentioned drawbacks, the present invention has been developed to provide a plurality of rings along the circumferential direction on the inner circumferential surface of the open end side of the pipe joint body of the annular packing installed between the short cylinder body and the pipe joint body. The present invention provides a pipe joint that eliminates the drawbacks of the conventional pipe joint by providing a notch.

(Structure) The gist of the present invention is that a female thread is provided on the inner circumferential surface of the opening end, a groove is provided along the circumferential direction on the inner circumferential surface of the deep part, and a jetty is provided in the deep part of the female thread along the circumferential direction. One end of the short cylindrical body is brought into contact with the jetty side surface of the pipe joint main body, and an annular packing is installed between the short cylindrical body and the pipe joint main body, and the opening of the pipe joint main body of the annular packing is attached. There is a pipe joint in which a plurality of notches are provided along the circumferential direction on the inner circumferential surface of the end portion.

Hereinafter, the present invention will be explained with reference to embodiments of the drawings.
FIG. 1 is a partially cutaway front view showing an example of the pipe joint of the present invention.

Reference numeral 1 denotes a pipe joint body, which has a tapered female thread 11 on the inner peripheral surface of its end, a groove 12 along the circumferential direction on the inner peripheral surface of the deep part, and a circumferential groove 12 on the inner peripheral surface of the deep part. A jetty 13 is provided along the direction,
An annular notch 131 is provided on the inner circumference of the side surface of the jetty 13, and the surfaces of the groove 12 and the jetty 13 are coated with an anticorrosive coating made of synthetic resin or the like. 2 is a short cylinder. The short cylindrical body 2 is made of a corrosion-resistant material such as stainless steel or polyphenylene sulfide resin, which does not deform even when an external force is applied thereto, and has a flange 21 provided outwardly at one end thereof. The inner diameter of the short cylindrical body 2 is approximately the same as the inner diameter of the jetty 3 of the pipe joint body 1,
Its length is longer than the width of the groove 12 of the pipe joint body 1. The short cylindrical body 2 is brought into contact with the flange 21 so as to have the same axis as the side surface of the jetty 13 of the pipe joint body 1, that is, the notch 131.

3 is an annular packing made of an elastic material;
As shown in FIG. 2, it is composed of a large diameter part 31 and a small diameter part 32, the width of which is slightly longer than the width of the groove 12 of the pipe joint body 1 and slightly shorter than the length of the short cylindrical body 2. ing. The large diameter portion 31 has a thickness larger than the distance between the short cylinder body 2 and the tapered female threaded portion 11, and has a plurality of notches 3 along the circumferential direction on the outer peripheral surface.
11 is provided, and a plurality of notches 312 are provided along the circumferential direction on the inner peripheral surface. If the depth of the notch 312 is made small, the elastic repulsive force of the annular packing 3 acting on the coating layer on the end surface of the internally coated steel pipe connected to the pipe joint body 1 will not be sufficiently alleviated. Since the elastic repulsive force of the annular packing 3 is reduced and sealing cannot be achieved at the end surface of the tube, it is preferable that the diameter of the tip of the notch be approximately equal to the inner diameter of the inner-coated steel tube.

The width of the small diameter portion 32 is approximately the same as the width of the groove 12 and smaller than the diameter of the groove 12. The annular packing 3 is attached between the short cylindrical body 2 and the pipe joint body 1 with a notch 311 engaged with a corner of the side wall of the groove 12 and the tapered female thread 11.

The short cylindrical body 2 and the annular packing 3 are attached to the pipe joint body 1.
For example, attach the annular packing 3 to the outer periphery of the short cylindrical body 2, insert it into the pipe joint body 1, and connect the notch 311 with the side wall of the groove 12 and the female thread 11. When the annular packing 3 is engaged with the corner portion of the annular packing 3, a part of the annular packing 3 is pressed between the tapered female threaded portion 11 and the short cylindrical body 2, and the flange 21 of the short cylindrical body 2 and the small diameter portion 32 of the annular packing 3 are pressed. The pipe joint of the present invention is formed by abutting and fixing one end surface of the pipe joint body 1 to the notch 131 of the jetty 13 of the pipe joint body 1 (see FIG. 1).

If the annular packing 3 is installed in a pressed state between the tapered female threaded portion 11 of the pipe joint body 1 and the short cylindrical body 2 as in the above embodiment, the annular packing 3 is attached to the short cylindrical body 2 and its outer circumference. The annular packing 3 is attached so as to have the same axis as the jetty 13 of the pipe joint body 1.

Further, an annular notch 131 is provided on the inner circumference of the side surface of the jetty 13, and the short cylindrical body 2 is provided in the notch 131.
When the flange 21 is fitted, the short cylindrical body 2 can be reliably fixed at a predetermined position on the jetty 13. When the flange 21 of the short cylindrical body 2 is fitted into the notch 131 of the jetty 13 in this way, the annular packing 3 is not necessarily inserted between the tapered female threaded part 11 of the pipe joint body 1 and the short cylindrical body 2. It is not necessary to attach it in a pressed state.

Next, one mode of use of the embodiment of the present invention shown in FIG. 1 will be explained with reference to FIG. 4.

Reference numeral 5 designates an inner-coated steel pipe connected by a pipe joint, and a corrosion-resistant coating layer 52 made of synthetic resin or the like is provided on the inner surface of the steel pipe 51, and a tapered male threaded portion 53 is provided on the outer peripheral surface of the pipe end. Pipe fitting body 1
When the tapered male threaded part 53 of the internally coated steel pipe 5 is screwed into the tapered female threaded part 11 of the internally coated steel pipe 5 and tightened, the end surface of the internally coated steel pipe 5 first comes into contact with the annular packing 3, and when further tightened, the annular packing 3
is compressively deformed, but since it is supported by the short cylindrical body 2, it does not bulge inward, but deforms toward the space of the groove 1, and the outer peripheral surface of the short cylindrical body 2 and the pipe end face of the inner-coated steel pipe 5 It is effectively compressed between the tube end surface of the inner-coated steel tube 5 and obtains sufficient sealing performance.

Note that the notch 13 of the jetty 13 in the above embodiment
1. The flange 21 of the short cylindrical body 2 is not necessarily essential.

Further, the annular packing 3 is not limited to the one shown in FIG. 2, but as shown in FIG. It may be buried. The diameter of the spring 4 is the steel pipe 5 of the inner-coated steel pipe 5.
The diameter is approximately equal to that of 1. In this case, the repulsive force of the spring 4 is also added, and the center position on which the elastic repulsive force of the annular packing 3 acts is located closer to the steel pipe 51 side of the internally coated steel pipe 5, so that the coating layer 52 on the end surface of the internally coated steel pipe 5 The peeling and peeling prevention effect is further improved.

The pipe joint of the present invention is constructed as described above, and the annular packing installed between the short cylinder body and the pipe joint main body has a plurality of rings along the circumferential direction on the inner circumferential surface of the open end side of the pipe joint main body. Since there is a cutout section,
When connecting an internally coated steel pipe to this pipe joint by screwing it in, even if the screw length is 15 mm or more, the excessive compressive force of the annular packing caused by the end face of the internally coated steel pipe will not be applied to the position of the coating layer. In the vicinity of the corresponding inner peripheral surface, as shown by the broken line B curve in Fig. 5, the maximum load that the coating layer can tolerate is 200 kg, which is relaxed by the plurality of notches provided along the circumferential direction. / ^cm2 .
Therefore, the elastic repulsive force of the annular packing that acts on the coating layer of the inner-coated steel pipe is reduced, and peeling and curling of the coating layer on the end face of the steel pipe is prevented.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view showing an embodiment of the present invention, Fig. 2 is a partially cutaway front view showing an enlarged annular packing used in the embodiment of the present invention, and Fig. 3 is a partially cutaway front view showing an annular packing used in the embodiment of the present invention. FIG. 4 is a partially cutaway front view showing an enlarged modification of the annular packing of the present invention; FIG. 5 is a partially cutaway front view showing the usage of the embodiment of the present invention; It is a curve diagram showing the relationship between the threaded length of the internally coated pipe and the pressing force on the end surface of the internally coated steel pipe in a pipe joint, where the A curve shows the conventional one, the B curve shows the one of the present invention, the solid line shows the total pressing force, and the broken line shows the relationship. is the pressing force acting on the coating layer. 1...Pipe joint body, 11...Female thread portion, 12...
... Concave groove, 13 ... Jetty, 131 ... Notch, 1
4... Corrosion-proof coating, 2... Short cylindrical body, 21... Flange, 3... Annular packing, 31... Large diameter part, 3
2... Small diameter part, 311, 312... Notch part.

Claims (1)

[Scope of utility model registration request] A jetty side surface of a pipe fitting main body, which has a female thread on the inner circumferential surface of the opening end, a groove along the circumferential direction on the inner circumferential surface of the deep part, and a jetty along the circumferential direction on the deep part of the groove. One end of the short cylinder is brought into contact with the
An annular packing is installed between the short cylindrical body and the pipe joint body, and a plurality of notches are provided along the circumferential direction on the inner circumferential surface of the annular packing on the open end side of the pipe joint body. A pipe fitting.