JPH07229590A - Stainless steel thin pipe joint - Google Patents

Abstract

PURPOSE:To sufficiently connect stainless steel thin pipes, in each of which a pipe end is expanded to be formed into a flare part, on site, to provide a high temperature durability, and to reduce a pipe internal resistance so as to minimize a residence clearance of fluid. CONSTITUTION:Inside faces 2a of flare parts 2 are brought into contact with both side taper parts 41, 42, while a soft alloy seal ring 40 with an inside diameter A equal to the inside diameter of a pipe is stored in respective circular storage grooves 30 formed in a pair of half bodies H constituting a joint main body, and a straight pipe part 3 of the pipe is supported by an inner circumferential face 11a, and subsequently, the half bodies 11 are fastened together by means of two bolts.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a joint for a thin stainless steel pipe as a liquid flow path.

[0002]

2. Description of the Related Art Various types of thin-walled stainless steel pipe joints have been proposed. Recently, a flare portion was formed by enlarging the pipe end into a trumpet shape, called a pipe expansion method, and a rubber seal ring was formed on the tapered surface of the flare portion. Although an inserted joint is known, in addition to the joint body being heavy and expensive, the seal ring undergoes a large change over time, and for some reason, when a fluid having a temperature higher than the normal operating temperature passes through, the seal ring deteriorates rapidly. To leak water. Further, the conventional joint has a drawback that the pipe length must be adjusted every time the joint is interposed in the pipe.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a joint which can be miniaturized and which can adopt high temperature resistant sealing means without using an elastic body such as rubber or plastic for a seal ring. is there. Further, the present invention provides a joint with which the pipe length of the connecting pipe can be easily set and the joint can be tightened without requiring special care, and which has good work efficiency in the field.

[0004]

SOLUTION: The joint of the present invention has a pipe end of 40 to 50 ° outward.
For a stainless thin-walled tube expanded at an angle of 4 to 6 to form a flare portion of 4 to 6 mm, which is formed on a pair of joint halves that also serve as tightening rings and on the inner peripheral portion of the joint halves. It is composed of a metal seal ring and two tightening bolts, which are closely accommodated together with the flare portion of the tube in the tapered groove with the surface. The stainless steel pipe is a pipe having a wall thickness of 0.8 to 1.5 mm whose outer diameter tolerance is defined based on JIS standard. The joint body is composed of a pair of halves, and each half is a casting of aluminum alloy ADC-6 (melting point about 500 ° C) and is molded together with a receiving groove and a bolt hole to hard anodize the surface to prevent contact potential corrosion. Is preferably applied. The seal ring is commonly called "white metal" (Zn, Al and other alloys), is a soft alloy with a melting point of about 350 ° C, is made by press molding, and has a surface coated with silicon with a thickness of about 0.5 mm. Those subjected to (heat resistance 230 ° C. to −60 ° C.) are preferable.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a tube end portion of a stainless thin-walled tube 1 having a flare portion 2 formed by press expansion. The length L of the inner surface of the flare portion is 4 to 6 mm depending on the pipe diameter. Three
Is a straight pipe part. Reference numeral 10 denotes an annular joint body, and the flanges 12, 13 and 17, 18 of the half bodies 11, 16 face each other, and the tightening bolts 21, 22 are screwed through the respective bolt holes 14, 19, 15 and 20. Are integrated together. If the bolts and screws are screwed only into the screw holes 19 and 20, the tightening work becomes easy. Reference numeral 30 denotes an annular accommodation groove formed on the inner peripheral surface of the main body, and taper portions 31 and 32 which are in contact with the outer surface 2b of the flare portion of the tube are provided on the inner surface side. Hard alumite processing is applied to the entire inner and outer surfaces of each half. Reference numeral 40 denotes a flexible metal seal ring formed of white metal, which has the same inner diameter A as the pipe 1, and has tapered portions 41 and 42 on both sides of the ring which are in contact with the flare inner surface 2a of the pipe. The V-shaped grooves 43 and 44 are provided, and the V-shaped grooves 43 and 44 are formed so as to be accommodated in the accommodation groove 30.

[0006]

[Built-in] The pipe end flare portions to be connected are respectively brought into contact with the taper portions 41 and 42 of the V groove of the seal ring, the seal ring 40 is interposed between the flare portions, and the seal ring 40 is directly accommodated in the housing groove of the half body 16. When positioned within 30, the straight pipe portion 3 of each pipe is supported by the inner peripheral surfaces 11a and 16a of the half body. In this state, cover the other half 11 and tighten the tightening bolt 2
When both halves are fastened by inserting 1 and 22, the taper portions 31 and 32 of the respective halves push the flare portion outer surface 2b of the pipe, and the inner surface 2a of the flare portion of the seal ring of the seal ring corresponding to the inner surface state The taper portions 41, 42 are brought into close contact with each other while being slightly deformed. In the present invention, the flare portion 2 has a pipe expansion angle of 40 to
The angle is 50 °, and when the length L of the inner surface of the flare portion is 5 mm, the shortening of the tube length is about 1.5 mm for one tube and about 3 mm between the opposing flare portions. That is, even if the facing distance d in the seal ring, that is, the thinnest portion is set to an apparent shortened length of the connecting pipe, it does not affect the mechanical strength of the seal ring. Utilizing this characteristic, extremely convenient piping work becomes possible. That is, in FIG. 4, L = (d /
2) + L · cos (40 ° to 50 °), so d =
By setting the distance d with respect to L so as to satisfy 2L (1-cos (40 ° to 50 °)), it is possible to treat the straight pipe as if it were cut or joined. It becomes possible to be freed from the trouble of having to adjust the pipe length each time.

[0007]

As described above, the piping work can be performed very efficiently by adopting the joint of the present invention. That is, the cutting work of the pipe and the fitting work of the joint according to the pipe length are simplified. Besides, since the seal ring of the present invention is made of a soft metal, there is no possibility of deterioration even when exposed to high temperatures, and therefore it is safe and durable even when used for piping near a boiler, for example. Further, since the joint body of the present invention is made of aluminum alloy, it is light in weight and smaller than the conventional product, so that it is easy to maintain a straight shape without causing bending even when the length of the pipe is long. Furthermore, since there is no protruding portion formed in the pipe and the gap between the seal ring and the flare portion is extremely small, there is little fluid retention (dead water), and therefore it can be used for piping in the food industry.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a tube end portion of an expanded tube.

FIG. 2 is a side view of an inside longitudinal section of the joint of the present invention.

FIG. 3 is a partially cutaway cross-sectional front view of the joint of the present invention.

FIG. 4 is a diagram showing a relationship between a tube end gap and a flare length in the joint of the present invention.

[Explanation of symbols]

 2 Expansion flare part 2a Flare part inner surface 2b Flare part outer surface 3 Straight pipe part 10 Joint body 11, 16 Joint body 11a, 16a Straight pipe part support inner peripheral surface 12, 13 Flange 19, 20 Bolt hole 21, 22 Tightening bolt 30 Storage groove 31, 32 Tapered portion 40 Soft metal seal ring 41, 42 Tapered portion 43, 44 V groove

Claims (4)

[Claims] 1. An annular joint for connecting a stainless thin-walled pipe having a flare portion whose pipe end is expanded to 40 to 50 °, having an inner diameter equal to that of the stainless pipe, and flaring on both side surfaces. A soft alloy seal ring having a taper portion that comes into contact with the inner surface of the portion, and an accommodating groove having a taper portion that accommodates the outer peripheral portion of the seal ring and that is in contact with the outer surface of the flare portion of the pipe. A joint body composed of a pair of halves having an inner peripheral surface for supporting a straight pipe portion connected to the flare portion on both sides is integrated by two fastening bolts screwed to both side flanges of the halves. Thin stainless steel pipe fittings. 2. The stainless thin pipe joint according to claim 1, wherein the half body is a cast product of aluminum alloy ADC-6, and the entire surface thereof is hard alumite treated. 3. The stainless thin-walled pipe joint according to claim 1, wherein a silicon coating is formed on the surface of the seal ring. 4. A distance d between flare portions facing each other with a seal ring sandwiched therebetween is d = 2L (1-
The stainless thin-walled pipe joint according to claim 1 or 3, which is set to have a relationship of cos (40 ° to 50 °).