JP4845536B2 - Anti-corrosion structure of pipe end face - Google Patents

Description

  The present invention relates to a pipe end face anticorrosion structure, and more particularly, to a pipe end face anticorrosion structure that can be applied to a case where a cut pipe is cut at a site where a cast iron pipe line is laid.

  In recent years, pipes made of cast iron such as waterworks are often replaced with pipes that do not have seismic performance at the joints to pipes that have seismic performance at the joints. The joint part of the pipes in the pipe having the seismic performance is connected to the outer periphery of the distal end of the insertion part of the other pipe inserted into the inside of the reception part of one pipe constituting the joint part. It is customary that a protrusion is formed to prevent it from slipping out.

  On the other hand, when laying a pipeline having such an earthquake-resistant function, the pipe may be cut to a predetermined length on the piping construction site due to the length of the pipeline to be laid. For example, when a valve is installed at a predetermined location along a pipeline, a straight pipe connected to the valve may be cut in correspondence with the installation position of the valve. Such construction is called a cut tube.

  Cast iron pipes are generally anticorrosive by painting their inner and outer surfaces and end faces. However, when a cut pipe is applied to the pipe, the metal ground of the pipe is exposed at the end face of the cut portion. For this reason, it is necessary to newly apply corrosion protection to the exposed portion.

  Patent Document 1 describes an example of the anticorrosion structure in such a case. FIG. 8 shows the anticorrosion structure described in Patent Document 1. Here, reference numeral 1 denotes a cast iron pipe, which is coated on the inner and outer surfaces, but the cut metal 2 is exposed at the cut end face 2 by being cut at the piping construction site. The end portion of the tube 1 including the cut end face 2 is covered with an anti-corrosion cap 3, and an annular protrusion 4 is formed on the outer periphery of the end portion of the tube 1 at the end portion of the tube 1 including the anti-corrosion cap 3. A ring body 5 made of cast iron is attached.

  The anti-corrosion cap 3 is formed of an elastic material such as rubber, and has a cross section formed in the shape of an Arabic numeral “7”, and a brim 6 that covers the cut end face 2 in close contact with the cut section 2; The inner surface contact portion 8 that is in close contact with the inner peripheral surface 7 at the end portion of the tube 1 and the outer surface contact portion 10 that is in close contact with the outer peripheral surface 9 at the end portion of the tube 1 are integrally provided. Before the anti-corrosion cap 3 is attached to the end of the tube 1, the angle formed by the collar portion 6 and the inner surface contact portion 8 is formed at an acute angle that is narrower than 90 degrees. The acute angle portion is elastically expanded by being attached to the end portion of the tube 1, and the collar portion 6 and the inner surface contact portion 8 are particularly connected to the tube 1 by the elastic force generated in the anticorrosion cap 3 at that time. The cut end face 2 and the inner peripheral face 7 can be pressed into contact with each other to form a close state as described above.

  In the anticorrosion cap 3, the inner surface contact portion 8 is formed to be thicker than the other portions, and the pressure contact force against the inner peripheral surface 7 of the tube 1 due to the elastic force acts greatly, so that the water in the tube is separated from the anticorrosion cap 3. It is prevented from entering between the inner peripheral surface 7 of the tube 1 and particularly between the collar portion 6 and the cut end surface 2. The inner surface contact portion 8 has an outer peripheral protrusion 11, and the portion of the outer peripheral protrusion 11 is in contact with the inner peripheral surface 7 of the pipe 1 intensively to increase the surface pressure. Have been able to ensure.

  The ring body 5 is formed, for example, in one piece in the circumferential direction, and a protrusion forming portion 13 that is fitted to the end of the tube 1 and a front end forming that is disposed so as to cover the cut end surface 2 of the tube 1. It is the structure by which the part 14 was integrally formed. The protrusion forming part 13 is integrally formed with an inner peripheral protrusion 15 having a rectangular cross section, and this inner peripheral protrusion 15 is formed on the outer periphery of the cast iron pipe 1 when the cast iron pipe 1 is cut. The ring body 5 can be attached to the pipe 1 in a state where the ring body 5 is positioned at a predetermined position by being fitted into the annular groove 16 having a rectangular cross section. Thereby, an annular protrusion 4 is formed on the outer periphery of the tip of the tube 1. The ring body 5 is fixed to the tube 1 by an appropriate means such as a tapping screw in a state where the inner peripheral protrusion 15 is fitted in the annular groove 16. At this time, the outer surface contact portion 10 of the anti-corrosion cap 3 is sandwiched between the ring body 5 and the tube 1 and compressed, thereby being held at that portion, and between the ring body 5 and the tube 1. Seal.

  In the state where the ring body 5 is positioned with respect to the tube 1 by the inner peripheral projection 15 being fitted in the annular groove 16 as described above, the front end forming portion 14 is formed on the collar of the anticorrosion cap 3 attached to the tube 1. It is arrange | positioned in the position which left the slight gap in the pipe-axis direction from the part 6, and can thereby form the front-end inclination part of the pipe | tube 1. FIG. Reference numeral 17 denotes an end surface of the front end forming portion 14 which is formed in a direction perpendicular to the tube axis direction so as to face the collar portion 6 of the anticorrosion cap 3.

According to such a structure, the edge part of the pipe | tube 1 is covered with the anti-corrosion cap 3 in a close state, thereby preventing water in the pipe from reaching the cut end face 2 and preventing the corrosion. Incidentally, the water around the pipe 1 such as ground water when the pipe 1 is buried in the ground is also sandwiched between the ring body 5 and the pipe 1 in the compressed state by the outer surface contact portion 10 of the anticorrosion cap 3 as described above. As a result, the cutting end surface 2 is prevented from reaching similarly.
JP 2005-248971 A

  However, in the configuration of FIG. 8, particularly when the water flow 18 in the pipe is a high-speed flow or a turbulent flow, the inner surface contact portion 8 is connected to the inner surface contact portion 8 of the anticorrosion cap 3. A force 19 in the direction of peeling from 7 may be applied. Then, although it is extremely rare, it may cause a decrease in the sealing performance of the inner surface contact portion 8. In addition, it is often necessary to cut the straight tube 1 at a location where the tube 1 is joined to a valve or a deformed tube such as a bent tube as described above. Since turbulent flow is likely to occur at these locations, it is desirable to take some measures.

  In view of the above, an object of the present invention is to provide an anti-corrosion cap that covers an end portion of a pipe to prevent the corrosion of the portion so that it is difficult to peel off due to the action of fluid in the pipe.

In order to achieve this object, the present invention covers the end portion of the metal tube that is cut and exposed on the end surface, with a corrosion protection cap formed of an elastic body,
The anti-corrosion cap has a collar portion that covers the end surface, an inner surface contact portion that contacts the inner surface of the metal tube, and an outer surface contact portion that contacts the outer surface of the metal tube,
Cover the end of the metal tube with a ring body,
This ring body is fitted to the metal tube so that an annular protrusion can be formed on the outer periphery of the end of the metal tube, and the protrusion forming portion sandwiching the outer surface contact portion of the anticorrosion cap with the outer surface of the metal tube And a front end forming portion positioned with a gap in the tube axis direction from the collar portion of the anti-corrosion cap covering the end surface of the metal tube,
A holding member is provided at an end of the metal tube,
The holding member is formed in a ring shape that is divided by one in the circumferential direction , and includes a web portion disposed on the inner peripheral side of the inner surface contact portion of the anticorrosion cap, a collar portion of the anticorrosion cap, and a front end forming portion of the ring body have a flange portion disposed in the gap between,
The web portion of the holding member is held in an elastically sandwiched state between the inner surface contact portion of the anticorrosion cap and the inner peripheral surface of the metal tube in a state where the web portion is about to spread by elastic force.
A notch is formed at a predetermined position along the circumferential direction of the holding member .

  According to the present invention, the holding member having the web portion disposed on the inner peripheral side of the inner surface contact portion of the anticorrosion cap, and the flange portion disposed in the gap between the collar portion of the anticorrosion cap and the front end forming portion of the ring body. Since the anticorrosion cap is held by the holding member, the inner surface contact portion of the anticorrosion cap may be peeled off due to the action of the fluid in the pipe, or the collar portion of the anticorrosion cap It is possible to prevent the covering function from deteriorating, and therefore, it is possible to reliably prevent corrosion of the cut end surface of the pipe.

Hereinafter, the anticorrosion structure of the pipe end face according to the embodiment of the present invention will be described in detail with reference to FIGS. 1 to 7 and the same members as those shown in FIG.
As shown in FIG. 1, a cast iron ring body 5 is mounted to form an annular protrusion 4 on the outer periphery of an end portion of a cast iron pipe 1 subjected to a cut pipe.

  The anticorrosion cap 3 is formed in the shape of the Arabic numeral “7” in the cross section similar to that shown in FIG. 8, and the collar portion 6 covering the cut section 2 and the inner peripheral surface 7 at the end of the tube 1. And an outer surface contact portion 10 in close contact with the outer peripheral surface 9 at the end of the tube 1. However, the inner surface contact portion 8 is formed thinner than that shown in FIG. 8, and does not have the outer peripheral projection 11 as shown in FIG. To be in contact with. A gap 21 is formed between the collar portion 6 of the anti-corrosion cap 3 and the end surface 17 of the front end forming portion 14 of the ring body 5 along the tube axis direction.

  A holding member 22 is provided at the end of the tube 1. The holding member 22 is formed in a ring shape that is divided into one part in the circumferential direction by a stainless material or the like, and is formed in an L-shaped cross section so that the inner periphery of the inner surface contact portion 8 of the anticorrosion cap 3 attached to the pipe 1 is formed. The web portion 23 disposed on the side and the flange portion 24 disposed in the gap 21 between the collar portion 6 of the anticorrosion cap 3 and the front end forming portion 14 of the ring body 5 are integrally provided.

  As shown in FIG. 2 (a), the holding member 22 formed in one piece in the circumferential direction is relatively large at one place along the circumferential direction before being attached to the end of the tube 1. The divided space 25 is used. When the holding member 22 is fitted into the end portion of the tube 1, the end portion of the tube 1 in a state where the anticorrosion cap 3 is attached after the cutting and the ring body 5 is not yet attached is shown in FIG. The web portion 23 of the holding member 22 that is elastically reduced in diameter so that the divided space 25 is contracted from the state shown in FIG. 5 is inserted, and then the holding member 22 is slightly expanded in diameter by its elastic force. It sticks to the inner periphery of the inner surface contact portion 8 of the anti-corrosion cap 3. FIG. 2B shows the state at that time. Thereafter, the ring body 5 is attached to the end of the tube 1. FIG. 1 shows the state at that time.

  In this way, the holding member 22 is more elastically reduced in diameter than the case shown in FIG. 2A, that is, in a state where the holding member 22 is about to expand due to the elastic force, as shown in FIGS. As shown, it is attached to the end of the tube 1. Then, the web portion 23 elastically sandwiches and holds the inner surface contact portion 8 of the anticorrosion cap 3 with the inner peripheral surface 7 of the tube 1. Thereby, the inner surface contact portion 8 of the anticorrosion cap 3 is strongly pressed against the inner peripheral surface 7 of the tube 1 and seals that portion to prevent water in the tube from entering the cut end surface 2 of the tube 1. . Further, since the inner surface contact portion 8 of the anticorrosion cap 3 can be held in close contact with the inner peripheral surface 7 of the tube 1 by the web portion 23 of the holding member 22, the inner surface contact portion 8 is formed by the action of the water flow in the tube. 1 can be prevented from being peeled off from the inner peripheral surface 7. Therefore, reliable corrosion prevention about the cut end face 2 is achieved.

  Since the flange portion 24 of the holding member 22 is disposed in the gap 21 between the end surface 17 of the front end forming portion 14 of the ring body 5 and the collar portion 6 of the anticorrosion cap 3, the flange portion 24 is formed with the web portion 23. Are positioned in the tube axis direction and the gap 21 is closed. For this reason, the web portion 23 of the holding member 22 can be positioned at a predetermined position, and the collar portion 6 and the inner surface are formed on the basis of the fact that the collar portion 6 of the anticorrosion cap 3 rises greatly from the cut end surface 2 even when the water flow in the pipe acts. It is possible to prevent the peeling of the contact portion 8. That is, FIG. 3 shows the case where the water flow 18 is generated in the direction of exiting from the pipe 1. In this case, the flange portion 24 of the holding member 22 in a state where the web portion 23 is pushed by the water flow 18 is the ring body 5. Further contact with the end surface 17 of the front end forming portion 14 prevents further displacement, thereby preventing the anti-corrosion cap 3 from peeling off.

  FIG. 4 shows the case where the water flow 18 is generated in the direction of entering the pipe 1. In this case, the flange portion 24 of the holding member 22 in a state where the web portion 23 is pushed by the water flow 18 is formed on the anticorrosion cap 3. Since only the collar portion 6 is pressed, the anti-corrosion cap 3 is similarly prevented from peeling off.

  For this reason, it can prevent that the peeling by the effect | action of the water flow 18 arises in the inner surface contact part 8 of the anti-corrosion cap 3, or the fall of the function in which the collar part 6 of the anti-corrosion cap 3 covers the cutting | disconnection end surface 2 of the pipe | tube 1 occurs. Therefore, reliable corrosion prevention of the cut end surface 2 of the tube 1 can be achieved.

  The holding member 22 can be formed at low cost by bending a long member having an L-shaped cross section so as to bend into a C shape as shown in FIG. In order to easily perform this bending process, it is preferable to use a long member having an L-shaped cross section and having a notch formed at an appropriate position along the length direction. The holding member 22 formed using such a long member is as shown in FIG. 5, and the notch 26 is disposed at an appropriate position along the circumferential direction of the holding member 22 as shown. Become.

  Alternatively, in order to further improve the bending workability, the number of notches in the long member can be made larger than in the above case. FIG. 6 shows an example of the holding member 22 formed by bending such a long member. Here, each notch 26 is formed at a number of positions along the circumferential direction of the holding member 22 so that the dimension along the length direction of the holding member 22 does not become too large.

  FIG. 7 shows an anticorrosion structure for a pipe end surface according to another embodiment of the present invention. Here, when the inner surface contact portion 8 of the anti-corrosion cap 3 is provided with a step portion 27 for accommodating the web portion 23 of the holding member 22, the anti-corrosion is obtained when the web portion 23 of the holding member 22 is accommodated in the step portion 27. For example, the inner surface of the inner surface contact portion 8 of the cap 3 and the inner surface of the web portion 23 of the holding member 22 are flush with each other. By comprising in this way, it can prevent that the web part 23 of the holding member 22 protrudes to an inner side of radial direction rather than the inner surface of the inner surface contact part 8 of the anti-corrosion cap 3, and becomes resistance with respect to a water flow. In addition, although the front-end | tip part of the inner surface contact part 8 of the anti-corrosion cap 3 becomes thicker than another part by forming the step part 27, this inner part taper surface 28 is formed in this part, and this It can prevent that the part which becomes thick becomes resistance with respect to a water flow.

It is sectional drawing which shows the anti-corrosion structure of the pipe end surface of embodiment of this invention. It is a side view which shows the ring body in FIG. 1, and its mounting state. It is a figure which shows a mode when the water flow in a pipe | tube acts in the anticorrosion structure of FIG. It is a figure which shows a mode when the water flow in a pipe | tube acts in another direction in the anticorrosion structure of FIG. It is a figure which shows the other example of a ring body. It is a figure which shows the further another example of a ring body. It is sectional drawing which shows the anticorrosion structure of the pipe end surface of other embodiment of this invention. It is sectional drawing which shows the anticorrosion structure of the conventional pipe end surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pipe | tube 2 Cutting | disconnection end surface 3 Corrosion prevention cap 4 Annular protrusion 5 Ring body 6 Brim part 8 Inner surface contact part 10 Outer surface contact part 13 Projection part formation part 14 Front end formation part 21 Gap 22 Holding member 23 Web part 24 Flange part

Claims (1)

Put the anti-corrosion cap formed of an elastic body on the end of the metal tube that has been cut and the ground of the end face is exposed,
The anti-corrosion cap has a collar portion that covers the end surface, an inner surface contact portion that contacts the inner surface of the metal tube, and an outer surface contact portion that contacts the outer surface of the metal tube,
Cover the end of the metal tube with a ring body,
This ring body is fitted to the metal tube so that an annular protrusion can be formed on the outer periphery of the end of the metal tube, and the protrusion forming portion sandwiching the outer surface contact portion of the anticorrosion cap with the outer surface of the metal tube And a front end forming portion positioned with a gap in the tube axis direction from the collar portion of the anti-corrosion cap covering the end surface of the metal tube,
A holding member is provided at an end of the metal tube,
The holding member is formed in a ring shape that is divided by one in the circumferential direction , and includes a web portion disposed on the inner peripheral side of the inner surface contact portion of the anticorrosion cap, a collar portion of the anticorrosion cap, and a front end forming portion of the ring body have a flange portion disposed in the gap between,
The web portion of the holding member is held in an elastically sandwiched state between the inner surface contact portion of the anticorrosion cap and the inner peripheral surface of the metal tube in a state where the web portion is about to spread by elastic force.
An anticorrosion structure for a pipe end surface , wherein a notch is formed at a predetermined position along the circumferential direction of the holding member .

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