JP3572415B2 - Manufacturing method of stainless steel pipe having joint for preventing corrosion - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a stainless steel pipe that can easily secure the toughness , sealing property, anti-corrosion property, piping workability, and the like of the flared end, and has a better insulation sleeve mounting workability than the conventional one. Also, the present invention relates to a method for manufacturing a stainless steel pipe that can be manufactured at low cost.
[0002]
[Prior art]
In recent years, flexible stainless steel pipes with bellows have been widely used as water pipes from the viewpoints of prevention of red water generation due to high durability, and absorption of displacement due to earthquake, constant vibration, ground subsidence, etc. I have.
[0003]
In addition, one end of a stainless steel pipe is connected to a water supply pipe buried on a public road through a saddle water faucet and joints, and the other end of the stainless steel pipe is shut off water through joints. A tap, a water tap, etc. are connected and branched into the residential land.
[0004]
In order to perform such piping work quickly and easily, stainless steel pipes having the following end structures are frequently used. That is, as shown in FIG. 6, one end of a stainless steel tube 1 having a bellows portion 1a is formed as a straight tube portion 2 having a flared end 3, and a cap nut 4 made of a dissimilar metal is loosely mounted on the straight tube portion 2. The cap nut 4 is attached so as to be freely fitted, and a stop wire 5 inserted into the inner peripheral groove 4a of the cap nut 4 contacts the flange 3a of the flare end 3 to prevent the cap nut 4 from coming off. A male screw of another member such as a joint is screwed into the female screw 4b formed on the peripheral surface so that a pipe connection operation at a construction site is easily performed.
[0005]
[Problems to be solved by the invention]
By the way, if the cap nut 4 is made of stainless steel, the cost is significantly increased. Conventionally, a cap nut made of yellow steel, which is a metal different from a stainless steel pipe, is used. Between the cap nut 4 made of stainless steel and the stainless steel pipe 1, there is a problem that electrolytic corrosion occurs due to different kinds of metals.
[0006]
In order to prevent the occurrence of electrolytic corrosion due to dissimilar metals, an insulating seal may be provided between the two, and for example, there is an insulating flexible body as disclosed in Japanese Utility Model Laid-Open No. 7-20497. However, when this type of stainless steel pipe is subjected to flaring on its straight pipe part, the material structure is deformed, so it is necessary to perform annealing to correct the deformation of the material structure. If pre-attached to the straight pipe portion, the insulating sleeve will be damaged by heat during annealing.
[0007]
Also, when an insulating sleeve or the like is retrofitted to a straight pipe part, the inner hole of the insulating sleeve cannot be inserted through a flared end with a diameter larger than its diameter, so the number of parts increases or the manufacturing process increases. However, the insulation sleeve cannot be easily and inexpensively attached to the straight pipe portion.
[0008]
The present invention has been made based on such regrets, and a stainless steel pipe having a bellows portion is provided with a joint for anti-corrosion prevention, which has better mounting workability than conventional, and has good sealing performance at low cost. It is an object of the present invention to provide a method of manufacturing a stainless steel pipe which is attached to a straight pipe part and has excellent pipe workability.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a cap nut made of a dissimilar metal is provided on a straight pipe portion on one end side of a stainless steel pipe via a flared end portion and a stop wire. In the manufacture of stainless steel pipes that can be loosely fitted while trying to prevent them from falling off, a bellows portion is formed at the center of the stainless steel pipe, and a flared end is formed by flaring the end of the straight pipe at one end. Then, after subjecting the flared end of the stainless steel pipe to an annealing treatment to correct the deformation of the material structure due to the flaring, the stop line and the cap nut are straightened from the flared end side of the stainless steel pipe to the straight pipe of the stainless steel pipe. Half of a cylindrical body attached to the straight pipe portion, a flange having a diameter slightly larger than the flared end is stretched from one end and a cut portion is formed in the longitudinal direction. Shaped insulation The reed is mounted on the straight pipe portion with the diameter increased through the cut portion, and a gap generated between the outer peripheral surface of the flared end and the inner peripheral surface of the cap nut is formed in the flange of the insulating sleeve. The outer peripheral part is mounted so as to be sealed, and the insulating sleeve is engaged with the flared end, the stop line is engaged with the insulating sleeve, and the cap nut is engaged with the stop line. A joint portion is formed in the straight pipe portion.
[0010]
[Action]
According to the present invention, the flared end is formed at the end of the straight pipe portion of the stainless steel pipe, and the flared end is annealed to correct the deformation of the material structure, and then the dissimilar metal joint is detachably insulated. Since the flare end is formed and annealed via the sleeve, it is attached to the straight pipe of the stainless steel tube with good sealing after retrofitting, so that the toughness of the flare end is ensured, and there is no melting of the insulating sleeve, preventing corrosion. Since the stainless steel pipe is provided with the bellows portion secured, it is possible to improve the fitting workability and reduce the cost of the joint at the time of manufacturing, and to improve the pipe workability and the workability at the piping site.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory sectional view showing a first embodiment according to the present invention.
[0012]
In FIG. 1, reference numeral 10 denotes a flexible stainless steel tube having a bellows portion 10a. One end of the stainless steel tube 10 is formed by a straight tube portion 11 and a flare end portion 12. 12a is a flange at the flare end 12.
[0013]
Reference numeral 13 denotes a commonly used yellow steel cap nut having a female screw 13a formed on the inner peripheral surface thereof and an inner peripheral groove 13b into which the stopper wire 14 is inserted. Since the inner diameter of the cap nut 13 is formed to be slightly larger than the diameter of the flange 12a, the cap nut 13 moves from the flare end 12 to the straight pipe section 11 without being obstructed by the flange 12a. It is inserted and fitted to the straight pipe portion 11 so as to be freely fitted.
[0014]
When the stop wire 14 is inserted into the inner circumferential groove 13b formed on the inner circumferential surface of the cap nut 13, the stop wire 14 protruding from the inner circumferential groove 13b abuts on the flange 12a of the flare end portion 12. The cap nut 13 is prevented from coming off.
[0015]
Reference numeral 15 denotes an insulating sleeve. As shown in FIGS. 2 and 3, the insulating sleeve 15 includes a cylindrical body 15a covering the outer peripheral surface of the straight pipe portion 11, and a flange 15b provided at one end of the cylindrical body 15a. It is formed as a half- cut (half-split) sleeve having a cutout 15c provided in the longitudinal direction, and is forcibly developed and mounted from the cutout 15c at the time of insertion.
[0016]
In this embodiment, the insulating sleeve 15 is made of a polypropylene resin and is formed to withstand a load of 800 kg. However, any material may be used as long as it has the above-described action.
[0017]
The outer periphery of the flange 15b of the insulating sleeve 15 is formed to have a slightly larger diameter than the flange 12a at the flared end, so that the outer peripheral portion of the flange of the insulating sleeve 15 is in contact with the outer peripheral surface of the flange 12a at the flared end. The gap generated between the cap nut 13 and the inner peripheral surface is sealed.
[0018]
Further, a short cylindrical portion 15d is formed so as to protrude from the outer periphery of the flange 15b of the insulating sleeve 15, and the short cylindrical portion 15d is inserted into a gap formed between the outer peripheral surface of the flange 12a and the inner peripheral surface of the cap nut 13. It may be configured as follows.
[0019]
Further, depending on the load and the like, the material of the insulating sleeve 15, the formed thickness, and the like, the shape of the stopper wire 14 is not limited to a spherical shape, and may be, for example, an elliptical shape so as to equalize the pushing force. .
[0020]
Next, a method for manufacturing a stainless steel pipe in this embodiment will be described. First, a stainless steel tube 10 having a bellows portion 10a formed in a central portion is prepared, and a straight tube portion 11 at one end side is flared to form a flared end portion 12, and the flared end portion is subjected to an annealing treatment to be flared. Correct the deformation of the material structure due to processing. Thereafter, the stop wire 14 and the cap nut 13 are inserted from the flare end portion 12 side into the straight pipe portion 11 and engaged therewith, and a half-split insulating sleeve 15 provided with a cutout portion 15c in the longitudinal direction is attached. When the insulating sleeve 15 is mounted, the notch portion 15c is expanded while being developed, and the insulating sleeve 15 is mounted on the straight pipe portion 11.
[0021]
That is, according to the method for manufacturing a stainless steel pipe in this embodiment, after forming the tough flare end portion 12, the insulating sleeve 15 can be easily retrofitted without being melted by the annealing treatment. By covering the outer peripheral surfaces of the straight pipe portion 11 and the flared end portion 12, it is possible to prevent electric corrosion between the stainless steel pipe 10 and the cap nut 13 made of dissimilar metal with good sealing properties via the insulating sleeve 15.
[0022]
Next, a reference example in FIG. 5 will be described. This reference example is used as a flexible joint. That is, the flexible stainless steel tube 20 having the bellows portion 20a has its outer periphery covered with a metal braid-shaped blade 21, and both ends are formed as straight tube portions 22 and 23.
[0023]
The side of the straight pipe section 22 is a flared end 24 having a flange 24a at its end, and a stainless steel sleeve 25 is attached to the outer periphery thereof. An annular groove 25a is formed on the outer periphery of the sleeve 25, and the end of the blade 21 is pressed by a press ring 26 in the annular groove 25a and caulked to prevent the sleeve 25 from coming off the stainless steel tube 20. Is done.
[0024]
Reference numeral 27 denotes a cap nut. The cap nut 27 has a female screw 27a formed on an inner peripheral surface thereof, and is screwed and connected to a male screw of another member such as a gate valve or a saddle tap. Reference numeral 27b denotes an inner circumferential groove. A stop wire 28 is inserted into the inner circumferential groove 27b. The stop wire 28 abuts the flange 24a of the flare end 24 to prevent the cap nut 27 from coming off. Is achieved.
[0025]
On the other hand, a shimoku 29 is attached to the outer periphery of the straight pipe portion 23, and an annular groove 29a is formed on the inner peripheral surface of the shimoku 29, and an annular groove 29b is also formed on the outer peripheral surface. Reference numeral 30 denotes an O-ring, which is pressed by a bulging portion 23 a formed in the straight pipe portion 23. Reference numeral 31 denotes a press ring. The end of the blade 21 is pressed by the press ring 31 and caulked to prevent the shimoku 28 from coming off the stainless steel pipe 20. 32 is a male screw formed on the outer periphery of the shimoku 28, and 33 is a rubber cover.
[0026]
In this embodiment, similarly to the above embodiment, it is possible to prevent electric corrosion between the stainless steel pipe 20 and the cap nut 27 which is a dissimilar metal with good sealing properties, and to provide a good flexible joint. In any case, in the present invention, the insulating sleeve is detachably attached to the outer peripheral surface of the straight pipe portion or the flared end portion forming the end portion of the stainless steel pipe after annealing of the flared end portion, so that the insulating sleeve is covered. It is possible to manufacture a stainless steel pipe having an electric corrosion preventing joint having good mounting workability and good sealing performance at low cost. In addition, since it can be installed as a water supply pipe or the like as it is at the piping site, it is possible to improve the piping workability and reduce the cost.
[0027]
【The invention's effect】
As described above, according to the present invention, a flared end is formed on a straight pipe portion on the end side of a stainless steel pipe having a bellows portion at a central portion, and the flared end is annealed. Then, the joint part, which is a dissimilar metal, can be detachably attached to the straight pipe part of the stainless steel pipe, so that the outer periphery of the flange seals the gap between the outer periphery of the flared end and the inner periphery of the cap nut. Since the insulating sleeve is attached, the toughness of the flared end is ensured, the insulating sleeve is not melted, and a joint having good sealing performance and anti-corrosion property can be attached.
For this reason, tough stainless steel pipes with bellows, which are required to absorb displacement due to earthquakes, constant vibrations, and ground subsidence, etc. It can be manufactured while reducing the amount.
Further, at the time of piping, since it can be used as a water supply pipe or the like without any processing at the piping site, there is an effect that the workability of the piping can be improved and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory sectional view showing a first embodiment according to the present invention.
FIG. 2 is an external front view showing a sleeve according to the present invention.
FIG. 3 is an external side view of a sleeve in FIG. 2;
FIG. 4 is an external front view showing another example of the sleeve according to the present invention.
FIG. 5 is an explanatory sectional view showing a reference example according to the present invention.
FIG. 6 is an explanatory sectional view showing an example of a conventional stainless steel pipe end.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Stainless steel pipe 10a Bellows part 11 Straight pipe part 12a Flange 13 Cap nut 14 Stop wire 15 Insulation sleeve

Claims (1)

In the manufacture of a stainless steel pipe, a cap nut made of a dissimilar metal is loosely fitted to the straight pipe part on one end side of the stainless steel pipe while trying to prevent it from coming off via the flared end and a stop wire.
A bellows portion is formed at the center of the stainless steel pipe, and a flared end is formed by flaring the end of the straight pipe portion at one end, and the material structure is deformed by flaring at the flared end of the stainless steel pipe. After straightening the stainless steel pipe, the stop wire and the cap nut are inserted through the straight pipe part of the stainless steel pipe from the flared end side of the stainless steel pipe and engaged therewith, and the cylinder is mounted on the straight pipe part. A half-split insulating sleeve in which a flange with a slightly larger diameter than the flare end is stretched from one end of the body and a cut portion is provided in the longitudinal direction, the diameter is expanded through the cut portion, Attached detachably to the straight pipe part, attached so that the gap formed between the outer peripheral surface of the flared end and the inner peripheral surface of the cap nut is sealed by the outer peripheral portion of the flange of the insulating sleeve, and attached to the flared end. The above insulation sleeve A joint for preventing electrolytic corrosion, characterized in that the stop wire is engaged with the insulating sleeve, and the cap nut is engaged with the stop line to form a joint portion in a straight pipe portion of the stainless steel pipe. A method for producing a stainless steel pipe having a portion.

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