JP3520481B2 - Anti-corrosion structure at the end of stainless steel pipe - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an end portion of a stainless steel tube which is easy and inexpensive to prevent electrolytic corrosion at a connection end portion of the stainless steel tube and has excellent durability. It is about structure. 2. Description of the Related Art In recent years, flexible stainless steel pipes having bellows have been developed from the viewpoint of preventing red water from being generated due to high durability and absorbing displacement due to earthquakes, constant vibrations, and ground subsidence. It has been widely adopted for water supply piping. [0003] In such a water supply pipe, 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 fittings, and the other end of the stainless steel pipe is connected to fittings. A water stopcock, a water tap and the like are connected through the pipe, and the branch pipe is branched into the residential land. However, 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 flared 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 plan at a construction site is easily performed. When the cap nut 4 is made of stainless steel, the cost is significantly increased. Therefore, conventionally, the cap nut 4 is made of brass, which is a metal different from a stainless steel pipe. Although cap nuts are used, between the cap nuts 4 made of brass and the stainless steel pipe 1, electric corrosion occurs due to different metals. In order to prevent the occurrence of electrolytic corrosion caused by dissimilar metals, an insulating seal may be provided between the two. However, this kind of stainless steel pipe is not easily deformed at the flared end of the flared material. It is necessary to perform annealing in order to correct the problem, and since the cap nut 4 made of dissimilar metal is attached so as to be able to be loosely fitted while preventing the nut from being subsequently removed, an insulating member which is particularly removable and can be attached later is required. The present invention has been made in view of such circumstances, and can be detachably attached to a connection end of a stainless steel pipe, thereby preventing electric contact at the connection end easily and at low cost. In addition, an object of the present invention is to provide a structure for preventing corrosion of stainless steel pipe ends which is excellent in durability. According to the present invention, in order to achieve the above object, a cap nut made of a dissimilar metal is provided on a straight pipe portion at one end of a stainless steel pipe via a flared end. In the structure of the end of the stainless steel pipe, which is attached freely to prevent loosening, the flared end formed on the straight pipe at one end of the stainless steel pipe is annealed to correct the deformation of the material structure. A cylindrical portion that is formed to have substantially the same thickness as the circumference, covers the straight pipe portion of the stainless steel pipe, and has an end surface serving as a flange provided on the flared end, and is cut in the longitudinal direction. A part is provided and provided with a half-split insulating sleeve that can be repeatedly developed with the cylindrical portion at a position facing the cut portion as a base point, and a straight pipe portion of a stainless steel pipe and a flare end after annealing. On the outer surface, It is characterized in that the insulating sleeve developed through the cutout portion is detachably retrofitted and covered, and electrolytic corrosion between the stainless steel pipe and the cap nut made of dissimilar metal is prevented through the insulating sleeve. According to the present invention, a flared end is formed in a straight pipe portion forming an end of a stainless steel pipe, and in particular, the flared end is annealed to correct the deformation of the material structure.
After that, the outer surface of the straight pipe and the flared end is covered with a detachable insulating sleeve, which is attached later, so that even if a dissimilar metal cap nut is attached through this insulating sleeve, the stainless steel pipe end In addition, the electric contact between them is easily and inexpensively prevented, and since the deformation of the material structure at the flared end is corrected, the durability is excellent. An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an explanatory sectional view showing a first embodiment according to the present invention. In FIG. 1, reference numeral 10 denotes a flexible stainless steel pipe having a bellows portion 10a. One end of the stainless steel pipe 10 is formed by a straight pipe portion 11 and a flared end portion 12. 12a is a flange at the flare end 12. In addition, the flare end 12 is the straight pipe 1
1 is formed by performing a flaring process as a tube expansion process. Reference numeral 13 denotes a commonly used brass 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. The inner diameter of the cap nut 13 is equal to the diameter of the flange 12a.
Is formed slightly larger than the diameter of the cap nut.
3 is a flare end 1 without being disturbed by the flange 12a.
It is inserted into the straight steel pipe part 11 from the two sides, and is attached to the straight pipe part 11 so as to be freely fitted. 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 inner circumferential groove 1b is inserted.
The stop wire 14 protruding from 3b abuts on the flange 12a of the flared end 12 to prevent the cap nut 13 from coming off. Reference numeral 15 denotes an insulating sleeve. The insulating sleeve 15 is, as shown in FIGS.
And a flange 15b provided at one end of the cylindrical portion 15a.
The name is formed as a half-split sleeve having a cutout 15c provided in the hand direction. When the sleeve is inserted, the cutout 15c is forcibly expanded and attached. In this embodiment, the insulating sleeve 15 is formed of a polypropylene resin,
Although it is formed to withstand the load of g, any material may be used as long as it has the above-described action. The flange 1 of the insulating sleep 15
The outer periphery of 5b is formed to have a slightly larger diameter than the flange 12a of the flare end portion 12, so that the flange 12a
Of the cap nut 13 is sealed. Further, the flange 15 of the insulating sleeve 15
15b, a short cylindrical portion 15d is formed so as to protrude from the outer periphery of the flange 1b.
The short cylindrical portion 15d may be configured to be inserted into a gap generated between the outer peripheral surface of 2a and the inner peripheral surface of the cap nut 13. The shape of the stop wire 14 is not limited to a spherical shape but may be, for example, an elliptical sphere, so that the pressing force is equalized by opening the load, the material of the wrapping sleeve 15 and the thickness of the formed sleeve. May be. According to this embodiment, the insulated sleeve 15 is easily attached to the straight pipe portion 11 of the stainless steel pipe 10 to which the cap nut 13 is previously loosely fitted by unfolding while expanding the cut portion 15c. The outer peripheral surfaces of the straight pipe portion 11 and the flared end portion 12 are covered with the insulating sleeve 15, and the stainless steel pipe 1 is covered with the insulating sleeve 15.
Electrolytic corrosion between zero and the cap nut 13 made of dissimilar metal can be prevented. Next, a reference diagram in FIG. 5 will be described. The one in this reference diagram 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 thereof are straight tube portions 2a.
2, 23. The straight pipe portion 22 has a flange 24 at its end.
In addition, a flared end 24 having an a is provided, 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. . Reference numeral 27 denotes a cap nut.
The female thread 27a is formed on the inner peripheral surface thereof, and is screwed and connected with a male screw of another member such as a gate valve or a saddle tap.
Reference numeral 27b denotes an inner peripheral groove, and a stop wire 28 is inserted into the inner peripheral groove 27b.
4 comes into contact with the flange 24a, so that the cap nut 2
7 is prevented. On the other hand, a shimoku 29 is attached to the outer periphery of the straight pipe portion 23. 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.
Is pressed and caulked to prevent the shimoku 28 from coming out of the stainless steel pipe 20. 32 is Shimoku 2
Reference numeral 33 denotes a male screw formed on the outer periphery of 8, and 33 denotes a rubber cover. In this case, similarly to the above embodiment, electrolytic corrosion between the stainless steel pipe 20 and the cap nut 27 made of dissimilar metal can be prevented, and a good flexiple joint can be provided. As described above, according to the present invention, the ring-shaped insulating sleeve is not attached to the straight pipe portion while passing the straight pipe portion of the stainless steel pipe inside, but is made to have a cylindrical shape. Along the notch provided in the longitudinal direction of the part,
With the cylindrical portion opposite to the cut portion as the base point, the unfolded state is taken as a base point, the straight pipe portion is inserted into the insulating sleeve through the widened cut portion, and if the unfolded state of the insulating sleeve is stopped, the insulating sleeve is restored. It can be attached to the straight pipe as a sleeve with the diameter of the state, so flaring the straight pipe part of the stainless steel pipe and annealing the flared part without attaching the insulating sleeve, and then the insulating sleeve itself The retrofit to the straight pipe portion can be repeatedly performed without inserting a flare end portion having a larger diameter than that of the flare end portion. For this reason, it is possible to correct the material structure of the flared end without causing damage to the insulating sleeve, to improve durability, to reduce the number of parts, and to improve the workability in mounting while performing electrolytic corrosion. It is possible to provide a low-cost electric corrosion prevention structure at the end of a stainless steel pipe capable of preventing the occurrence of corrosion.

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 in the present invention. FIG. 6 is an explanatory sectional view showing an example of a conventional stainless steel pipe end. [Signs at night] 10 Stainless steel pipe 10a Bellows 11 Straight pipe 12a Flange 13 Cap nut 14 Stop wire 15 Insulation sleeve Number increased by correction of shipping number (number of inventions) 0

Claims (1)

(57) [Claims 1] A stainless steel pipe in which a cap nut made of a dissimilar metal is attached to a straight pipe portion on one end side of the stainless steel pipe via a flared end so as to be freely fitted while preventing the nut from coming off. In the structure of the end portion, the flared end formed in the straight tube portion on one end side of the stainless steel tube is subjected to annealing to correct the deformation of the material structure, and the entire circumference is formed with substantially the same thickness, A cylindrical portion that covers the straight pipe portion of the stainless steel pipe, and whose end surface is a flange attached to the flared end portion,
A cut-off portion is provided in the longitudinal direction, and a half-split insulating sleeve is provided that can be repeatedly deployed with the cylindrical portion facing the cut portion as a base point. The straight tube portion of the stainless steel pipe and the flare after annealing are provided. On the outer peripheral surface with the end portion, the above-mentioned insulating sleeve developed through the cutout portion is detachably attached afterwards and covered, and the electrolytic corrosion between the stainless steel pipe and the cap nut made of dissimilar metal through this insulating sleeve. A corrosion prevention structure at the end of a stainless steel pipe characterized by preventing corrosion.