WO2011055636A1

WO2011055636A1 - Stainless steel flexible pipe

Info

Publication number: WO2011055636A1
Application number: PCT/JP2010/068567
Authority: WO
Inventors: 宏之松山; 昌文高井良; 央岩崎
Original assignee: 新日鐵住金ステンレス株式会社
Priority date: 2009-11-05
Filing date: 2010-10-21
Publication date: 2011-05-12
Also published as: KR101380091B1; JP5719107B2; TWI524952B; KR20120082008A; CN102667288A; TW201130579A; JP2011099496A

Abstract

This stainless steel flexible pipe is made of a stainless steel sheet, which is metallic, and the material thickness of which is 0.2 - 0.4 mm or less. Furthermore, the stainless steel flexible pipe comprises a pliable section wherein a waveform shape is formed. The waveform shape is such that the ratio d/Dd is 15 -23, where d is the outside diameter (mm) of the basic pipe, and Dd is the depth between the crest and the trough; and that the relational expression d/p = 2.5 - 5.5 is satisfied, where d is the outside diameter of the basic pipe, and p is the crest-to-crest spacing. The stainless steel flexible pipe may comprise a basic pipe section at both ends or one end. A basic pipe section and a pliable section may be alternately disposed in a plurality of places. The whole flexible pipe may have a coiled shape formed by being helically spiraled. The stainless steel flexible pipe may, in addition to comprising a basic pipe section at both ends or one end, comprise a flared section at both ends or one end of the basic pipe section.

Description

Stainless steel flexible tube

The present invention relates to a stainless steel flexible tube.
This application claims priority based on Japanese Patent Application No. 2009-253978 filed in Japan on November 5, 2009, the contents of which are incorporated herein by reference.

An air conditioner is a heat exchanger through a refrigerant, and a copper pipe having excellent heat conductivity is generally used for its piping. In addition, since copper pipes are excellent not only in heat conductivity but also in workability, copper pipes are also used in connection pipes for indoor and outdoor units that do not involve heat conductivity. Here, in the case of a general household air conditioner, if the pipe length is about 4 to 5 m, it can be connected sufficiently. However, in the case of commercial air conditioners such as buildings and cranes, the indoor unit and the outdoor unit are often installed in remote locations, so the connecting pipe exceeds 10 m, and in some cases, close to 100 m may be required. . In such a case, since the thickness of the current copper pipe is 0.8 mm or more, there is a problem that the weight increases and the portability deteriorates. In addition, depending on the cooling capacity of the air conditioner, the pipe diameter of the connecting pipe becomes large, so that a bending device such as a bender is required for bending the pipe. Furthermore, since it is difficult to lengthen the piping, there is a problem that workability is very inferior, for example, the connection work between the piping is increased.
In addition, since the weight of the pipe increases, the cladding pipe is easily crushed at the pipe hanging position. For this reason, there is also a problem that the condensation is likely to occur on the outer surface of the pipe and the pipe is liable to rust. Therefore, in the present situation, a condensation prevention sheet is used to prevent the cladding tube from being crushed.

In order to solve the above problems, first, application of an aluminum alloy that is lighter than copper is being considered for weight reduction (see, for example, Patent Document 1). However, when an aluminum pipe is used, a copper pipe is welded to both ends for connection, and thus there is a problem that it takes time and cost for processing.

On the other hand, stainless steel is used for various indoor and outdoor water supply, hot water supply, gas piping, etc. due to its excellent corrosion resistance. Moreover, since stainless steel has high strength, it is possible to make a flexible pipe by reducing the plate thickness. Thereby, while being able to bend to some extent like a copper and an aluminum pipe (for example, refer to patent documents 2), considerable weight reduction is attained compared with the conventional copper pipe because board thickness is thin. For these stainless steel flexible tubes, austenitic stainless steels such as SUS304, 304L, 316, 316L are often used. Adoption of a ferritic stainless steel flexible pipe that is cheaper and less work-hardening than austenitic stainless steel is being considered for use in an automobile exhaust system (see, for example, Patent Document 3).

Therefore, the present inventors have intensively studied, examined the bending workability and flaring workability of the flexible tube so that it can be connected to an air conditioner using ferritic stainless steel, and the conditions of the material and corrugated shape. (See Patent Document 4). However, when this flexible pipe was actually connected to an air conditioner and evaluated, it was found that the flow of the refrigerant gas becomes strong and there is a possibility of generating fluid noise estimated to be caused by the waveform shape of the flexible pipe.

This fluid noise is presumed to be equivalent to the air column resonance phenomenon that occurs due to the flow of the duct, heat transfer tube group, and fuselage in the heat exchanger such as a gas heater and boiler. It is known that the frequency of Karman vortices emitted from the heat transfer tube group increases as the flow velocity of the gas flowing in the duct increases, and noise is generated in accordance with the air column resonance frequency of the duct (Non-Patent Document 1). ). In the flexible tube, it is presumed that fluid noise is generated due to the coincidence of the Karman vortex frequency generated due to the corrugated shape and the resonance frequency of the flexible tube with the gas flow. As a countermeasure against fluid noise of these flexible pipes, for example, a flexible pipe having a wall that prevents the air flowing inside the pipe from flowing into many grooves has been studied (for example, see Patent Documents 5 and 6). However, the methods described in

Patent Documents

5 and 6 have a problem that it takes a great deal of cost for industrially stable production.

JP 2003-275832 A JP 2006-177529 A JP 11-159616 A JP 2009-185351 A JP 2008-220922 A JP 2006-64126 A

The present invention has been made in view of the above problems, and is made of stainless steel that is economically superior, improves bending workability at the time of construction, and can prevent generation of fluid noise estimated to be caused by the flow of refrigerant gas. An object is to provide a flexible tube.

As a result of intensive studies to solve the above problems, the inventors of the present invention preferably increase the corrugated shape of the flexible tube in order to ensure bending workability during construction (see Patent Document 4). On the other hand, in order to suppress the fluid noise, it has been found that it is preferable to approach the straight pipe as much as possible. And in order to make this contradictory characteristic compatible, the shape which can make the bending workability of a flexible pipe and suppression of a fluid noise compatible was examined using various stainless steel. As a result, the inventors have found that the relationship between the outer diameter of the raw pipe, the mountain pitch of the flexible pipe, and the depth of the valley is important, and completed the present invention.

A stainless steel flexible tube according to an aspect of the present invention is made of metal stainless steel having a material plate thickness of 0.2 to 0.4 mm or less, and has a flexible portion in which a corrugated shape is formed. d (mm), the corrugated shape is the raw tube outer diameter d / mountain valley depth Dd: 15 to 23, and the pipe outer diameter d / peak to peak pitch p: 2. Satisfies 5 to 5.5.
The stainless steel flexible tube according to one embodiment of the present invention may have a base tube at both ends or one end.
In the stainless steel flexible tube according to an aspect of the present invention, a plurality of the tube portions and the flexible portions having the corrugated shape may be alternately arranged.
The flexible tube made of stainless steel according to one aspect of the present invention may have a coil shape in which the entire flexible tube is spirally turned.
The stainless steel flexible pipe according to one embodiment of the present invention may have a raw pipe portion at both ends or one end, and may further have a flared portion at both or one side of the raw pipe portion.

According to the stainless steel flexible pipe according to an aspect of the present invention, by defining the material plate thickness and the corrugated shape as described above, for example, connection pipes for air conditioners, particularly commercial air conditioner indoor and outdoor units, It is possible to reduce the weight of piping for air conditioning equipment. In addition, bending during construction is possible, and further, fluid noise due to the flow of refrigerant gas can be suppressed.
When the flexible pipe has the raw pipe portions at both ends or one end, it is possible to connect the indoor and outdoor units and the pipes by performing flare processing for connection at the construction site. In addition, when a plurality of raw tube portions and corrugated portions (flexible portions) are alternately arranged, it is possible to cut and connect at arbitrary positions.
When the entire flexible tube has a spirally coiled shape, the flexible tube having an arbitrary length can be carried and the workability is improved.
When a flexible pipe has a raw pipe part at both ends or one end, and further has a flare processing part at both or one of the raw pipe parts, it becomes possible to immediately connect without flare processing at the construction site. .

It is a schematic cross section which shows the stainless steel flexible pipe of embodiment of this invention. It is a schematic diagram explaining the stainless steel flexible tube of embodiment of this invention, and is a perspective view which shows the state wound up by the coil shape. It is a schematic diagram explaining the stainless steel flexible pipe of embodiment of this invention, and is a graph which shows the relationship between the waveform shape of a flexible pipe, bending workability at the time of construction, and fluid noise.

Hereinafter, embodiments of a stainless steel flexible tube according to an aspect of the present invention will be described with reference to FIGS. 1 to 3 as appropriate. In addition, since this embodiment is described in detail in order to better understand the gist of the stainless steel flexible tube according to one aspect of the present invention, the present invention is not limited unless otherwise specified. .

FIG. 1 is a sectional view of a stainless steel flexible tube 10 according to an embodiment of the present invention.
As shown in FIG. 1, a stainless steel flexible tube (hereinafter sometimes simply referred to as a flexible tube) 10 according to one embodiment of the present invention is made of stainless steel having a plate thickness of 0.2 to 0.4 mm or less. It is formed as a material. When the outer diameter of the tube is d (mm), the corrugated shape formed in the flexible tube 10 is the tube outer diameter d / mountain valley depth Dd: 15 to 23, and the tube outer diameter d / The pitch is roughly constituted so as to satisfy the pitch p from 2.5 to 5.5.

As shown in FIG. 1, the flexible tube 10 includes a flare processing portion 14 provided at an end portion, a raw tube portion 12, and a flexible portion 20 having a corrugated shape. In the flexible part 20, independent ridges 22 and valleys 24 along the circumferential direction of the peripheral surface of the flexible tube 10 are alternately arranged to form a wave shape. The flare nut 30 is inserted into the flexible tube 10 so as to be freely rotatable and slidable.

The flare nut 30 is used to connect the pipes by tightening with a predetermined torque, and is generally inserted into the flexible pipe before flare processing.

The shape of the waveform of the flexible portion 20 is not particularly limited. For example, the shape of the top of the peak and the bottom of the valley is generally curved, but even if it is an acute convex portion. good.

The waveform shape of the flexible portion 20 will be described in detail below with reference to FIG.
In one aspect of the present invention, the relationship between the corrugated shape of the flexible portion 20 and the outer diameter d of the raw tube is important. In one embodiment of the present invention, 1/2 of the difference between the crest outer diameter dm (mm) and the trough outer diameter dv (mm) is defined as the crest depth Dd (mm), and the next crest from the crest top The length to the top of the head is defined as the pitch P (mm) of the waveform shape. The ratio (d / Dd) of the outer diameter d (mm) of the raw tube to the depth Dd (mm) of the valley is 15 to 23, and the outer diameter d (mm) of the raw tube and the pitch P (mm ) Ratio (d / P) is preferably in the range of 2.5 to 5.5. More preferably, d / Dd is 17 to 21.5 and d / P is 2.5 to 4.

When the outer diameter d / mountain depth Dd is smaller than 15, the depth of the valley corresponding to the outer diameter of the pipe increases, so that distortion during bending is dispersed in several wave portions and is not easily buckled. As a result, workability is improved. However, the frequency of the Karman vortex resulting from the corrugated shape matches the air column resonance frequency of the flexible tube, and fluid noise is likely to occur. Further, when the outer diameter d of the raw tube / the depth Dd of the valley exceeds 23, the fluid noise is suppressed by relatively decreasing the depth of the valley. However, bending workability during construction deteriorates.
In addition, when the outer diameter d / pitch P is less than 2.5, the depth of the valley is relatively small, and fluid noise is suppressed. However, bending workability during construction deteriorates. Moreover, when the raw pipe outer diameter d / pitch P exceeds 5.5, the depth of the valley is relatively increased, and the workability is improved. However, fluid noise tends to occur.

The above-mentioned definition of the waveform shape is studied in the examples described later. FIG. 3 shows the results of arranging the bending workability during construction and the generation of fluid noise based on the data of Examples shown in Table 2 described later.

In one embodiment of the present invention, the “element tube” generally refers to a tube manufactured by electric resistance welding or arc welding using a steel strip or a steel plate, and in one embodiment of the present invention, a drawn tube is used. Including. The “element tube portion” indicates a portion where no flexible portion is provided.
The location of the raw tube portion 12 is not particularly limited, and may be arranged on both sides or one side of the flexible portion 20, and the plurality of raw tube portions 12 and the plurality of flexible portions 20 are alternately arranged. May be.

The raw tube outer diameter d is not particularly defined. However, for example, in a home air conditioner connection pipe, the outer diameter of the raw pipe of the refrigerant liquid pipe is 6.35 mm, and the outer diameter of the raw pipe of the refrigerant gas pipe is 9.52 mm. These two types of pipes having an outer diameter of the raw pipe are generally used. In the case of large commercial air conditioners, pipes with an outer diameter of 9.52 mm or quadrants are used as refrigerant liquid pipes. Further, as the piping for the refrigerant gas, a quadrant, a pipe having an outer diameter of 15.88 mm, 19.05 mm, or the like is used. In addition, pipes having an outer diameter of more than 20 mm may be used for air conditioning.
Therefore, in the present invention, it is preferable to appropriately determine the outer diameter d of the raw tube within a range of 6 to 30 mm.

In one embodiment of the present invention, the thickness of the stainless steel used as the material for the flexible tube 10 is 0.2 to 0.4 mm. When the stainless steel plate thickness is thinner than 0.2 mm, the strength as a flexible tube is lowered. Furthermore, it cannot process to a predetermined pipe expansion ratio at the time of flare processing, and the flared processing tip portion (flared processing portion) is constricted (cracked). Furthermore, considering the availability in the market, the lower limit of the thickness of the stainless steel is 0.2 mm. Further, if the thickness of the stainless steel exceeds 0.4 mm, the bending workability at the construction site is remarkably lowered.
Therefore, the thickness of the stainless steel material is 0.2 to 0.4 mm.

The composition of the stainless steel used in one embodiment of the present invention is not particularly limited. For example, as defined in JIS, SUS304, 304L, 316, 316L, etc. can be used if it is an austenitic stainless steel. For ferritic stainless steel, SUS430, SUS430J1L, SUS430LX, SUS436L, SUS436J1L, SUS444, or the like can be used. Ferritic stainless steel is inexpensive because it does not contain a large amount of Ni unlike austenitic stainless steel. In addition, ferritic stainless steel is superior in workability because it has less work hardening than austenitic stainless steel.

In one embodiment of the present invention, the method for manufacturing the flexible tube is not particularly limited. For example, a stainless steel plate having a thickness of 0.2 to 0.4 mm is used to produce a raw pipe as a welded pipe or a drawn pipe by an existing method, and then a corrugated shape is formed by pressing a blade-shaped mold against the raw pipe. The method of forming is mentioned. In addition, for example, a method of forming a flexible tube by forming a corrugation on a stainless steel plate using an uneven roll, and then welding the corrugated steel plate while winding it may be mentioned.

According to one aspect of the present invention, the corrugated shape of the flexible portion 20 has a tube outer diameter d / mountain valley depth Dd: 15 to 23, and a tube outer diameter d / peak to peak pitch P: When satisfying 2.5 to 5.5, it is possible to realize both bending workability during construction and suppression of fluid noise caused by the flow of refrigerant gas.
In addition, the stainless steel flexible pipe of one embodiment of the present invention has the raw pipe portions at both ends or one end, thereby facilitating flaring. For this reason, it becomes possible to connect the indoor and outdoor units and the pipes by performing flare processing for connection at the construction site. In particular, in the case of a long flexible pipe in which a plurality of flexible parts and a plurality of raw pipe parts are alternately arranged, the raw pipe part is cut at an arbitrary position according to the length required at the construction site, A flexible tube having an element tube at the end can be obtained.

In the example of the flexible tube 10 shown in FIG. 1, the flexible portion 20 is one in which the independent crests 22 and troughs 24 are arranged at a constant pitch (one pitch type), but is not limited thereto. . For example, a peak portion and a valley portion may be formed in a spiral shape on the peripheral surface portion. Further, when the flexible pipe 10 is actually used as a pipe, an ordinary home air conditioner requires a length of about 4 to 5 m as a connection pipe. Moreover, if it is piping, such as a building and a crane, it will exceed 10 m and it may become close to 100 m depending on the case. In consideration of the ease of transportation and the like in this situation, it is preferable that the whole is a coil shape (pipe-in-coil) wound up in a coil shape as in the example of the flexible tube 40 shown in FIG. . By setting it as such a structure, weight reduction is achieved compared with the conventional copper pipe, so that the length of a flexible pipe becomes long. For this reason, it is possible to carry a flexible pipe having an arbitrary length, and the workability including workability and handling during construction is improved. In the example shown in FIG. 2, the flexible portion 20 and the raw tube portion 12 are wound up at the same position. However, the positions of the flexible portion and the raw tube portion may be shifted by changing the lengths of the flexible portion and the raw tube portion, or by changing the coil diameter to be wound.

In the example of the flexible tube 10 shown in FIG. 1, a flared portion 14 is provided at the end. However, this flared portion may not be provided, and the raw tube portion 12 may be disposed at the end portion of the flexible tube 10, or the flexible portion 20 may be disposed at the end portion. Moreover, the flare processing part 14, the raw pipe part 12, or the flexible part 20 may be provided at both ends of the flexible pipe 10, or may be provided only at one end.
When the flared portion 14 is provided on both or one end of the flexible tube 10, it is possible to immediately connect without flaring at the construction site.

As described above, according to the stainless steel flexible tube according to one aspect of the present invention, by defining the material plate thickness and the corrugated shape as described above, for example, an air conditioner, in particular, a commercial air conditioner room It is possible to reduce the weight of connecting pipes for external units and piping for air conditioning equipment. In addition, bending during construction is possible, and further, fluid noise due to the flow of refrigerant gas can be suppressed. For this reason, the industrial effect is extremely high.

Hereinafter, examples of the stainless steel flexible pipe according to one aspect of the present invention will be given, and one aspect of the present invention will be described more specifically. However, one embodiment of the present invention is not limited to the following examples, and can be implemented with appropriate modifications within a range that can be adapted to the above-described purpose. Included in the range.

[Manufacture of flexible pipes]
First, using a steel plate having the components shown in Table 1 and the thickness shown in Table 2, a 9.52 mmφ, 15.88 mmφ, or 19.05 mmφ TIG welded pipe was manufactured. Steel type A is SUS430LX, and steel type B is SUS304.
Next, using the TIG welded pipe, according to the description in Table 2, a flexible part having a length of 170 mm and a plurality of raw pipe parts having a length of 30 mm are alternately arranged to produce a long flexible pipe having a total length of 4 m. did. Then, the flexible tube was wound into a coil shape for transportation, and a flexible tube pipe-in-coil having a coil diameter of about 1 m was obtained.
And about this flexible pipe pipe-in-coil, the raw pipe part pinched | interposed by the waveform-shaped part (flexible part) is cut | disconnected, it has a raw-tube part in both ends, and a corrugated flexible part in the center part A flexible tube having a length of about 1 m was cut out. Subsequently, using the cut-out flexible tube, bending workability and the presence or absence of generation of fluid noise were evaluated by the procedure described later.

[Evaluation test]
The flexible tube obtained by the above procedure was evaluated according to the procedure described below.
In addition, it is difficult to connect all the manufactured flexible pipes to an actual air conditioner and evaluate the occurrence of fluid noise. For this reason, the evaluation of the presence or absence of occurrence of fluid noise described below was performed as a simple evaluation. Then, several additional flexible pipes, pipes and coils were manufactured under the same conditions, and tested for air conditioning. This confirmed the presence or absence of abnormal noise in actual equipment.

<Bending workability>
(Test method)
The bending workability was evaluated by bending the flexible pipe 90 degrees using a bender with a bending R of 300 mm, assuming actual air conditioner construction.

(Evaluation criteria)
According to the above test method, the case where buckling or flattening did not occur during the bending process was accepted, and the case where buckling or flattening occurred was rejected. The results are shown in Table 2.

<Existence of fluid noise>
(Test method)
It is difficult to evaluate all flexible pipes connected to an actual air conditioner. For this reason, a rubber hose was connected to one end of the flexible tube. Then, evaluation was performed by flowing air from a gas cylinder through a rubber hose to a flexible pipe at a flow rate of 5 L / min at 1 atm.

(Evaluation criteria)
While flowing air at a flow rate of 5 L / min at 1 atm inside the flexible tube, fluid noise was measured using a noise meter at a position 50 cm away from the other end where the rubber hose of the flexible tube was not connected. Generally, the noise level when no fluid noise is generated is less than 50 dB, and when the noise level is 50 dB or more, abnormal fluid noise is generated. Moreover, when it becomes 60 dB or more, it becomes a fluid abnormal sound like a whistling sound which is annoying. Therefore, the case where the measured value is less than 50 dB is regarded as acceptable, and the case where the measured value is equal to or greater than 50 dB is regarded as unacceptable.

<Air conditioner connection test>
(Test method)
The flexible pipes that passed the fluid noise test and some of the flexible pipes that failed were actually connected to an air conditioner and evaluated.

(Evaluation criteria)
A flexible pipe pipe-in-coil was connected to the air conditioner. And the noise meter was fixed to the position 1m away from the piping of the air conditioner indoor / outdoor unit, and the presence or absence of abnormal noise was measured. Similarly to the above test method for the presence or absence of occurrence of fluid noise, the case where the measured value was less than 50 dB was accepted, and the case where the measured value was 50 dB or more was rejected.

Table 1 shows the material grade (component composition) of the flexible pipe, and Table 2 shows a list of evaluation results.

[Evaluation results]
As shown in Table 2, with respect to bending workability, in Examples 1 to 7 where the plate thickness was 0.2 to 0.4 mm, which is the specified range of the present embodiment, 90-degree bending could be performed. On the other hand, Comparative Example 1 in which the plate thickness is out of the specified range of the present embodiment and Comparative Examples 2 and 3 in which the waveform shape is out of the specified range of the present embodiment are very hard and therefore difficult to bend, I buckled along the way. From this, it has been clarified that the flexible pipes of Comparative Examples 1 to 3 are extremely difficult to be applied to uses such as connection pipes of air conditioner indoor and outdoor units that are bent manually.

Regarding fluid noise, it was confirmed that in Examples 1 to 7 where the plate thickness and the waveform shape were within the specified range of the present embodiment, no abnormal noise such as whistling noise was generated even when air was flown inside. However, in Comparative Examples 4, 5, and 6 in which the waveform shape deviated from the specified range of the present embodiment, an abnormal noise such as a whistling sound was generated. From this, it has been clarified that the flexible pipes of Comparative Examples 4 to 6 are extremely difficult to be applied to an air conditioner connection pipe or the like.

Next, the flexible pipes of Examples 3, 5, and 6 that passed the above fluid noise test and Comparative Example 5 that failed were connected to an actual air conditioner, and the presence or absence of abnormal noise was evaluated. As a result, no abnormal noise was generated in Examples 3, 5, and 6. In contrast, in Comparative Example 5, an abnormal noise such as a whistling sound was generated. Thus, the same result as the fluid noise test result was confirmed.

In addition, as described above, the results of the bending workability during construction and the occurrence of abnormal fluid noise are arranged in the graph of FIG. 3 for the data of the examples and comparative examples shown in Table 2. In the graph of FIG. 3, the left side is an evaluation result of bending workability and the right side is an evaluation result of occurrence of fluid noise at the plot positions of “◯ (passed)” and “× (failed)”.
As is apparent from the graph of FIG. 3, the flexible pipe of the example (within the range specified in the present embodiment) having the waveform shape defined in the present embodiment is capable of bending workability and generation of fluid noise. Each of the evaluations is a pass (◯), and these properties are excellent.

From the results of the examples described above, the stainless steel flexible pipe of one aspect of the present invention is economically excellent, the bending workability during construction is improved, and the fluid is estimated to be caused by the flow of the refrigerant gas It became clear that the generation of noise could be prevented.

According to the flexible tube made of stainless steel according to one aspect of the present invention, it is excellent in bendability during construction and fluid noise is suppressed. Further, the weight can be reduced and the workability can be greatly improved as compared with the conventional copper pipe. For this reason, the flexible pipe made of stainless steel of one embodiment of the present invention can be used as, for example, an air conditioner connection pipe, and the industrial utility value is extremely large.

DESCRIPTION OF SYMBOLS 10 ... Stainless steel flexible pipe (flexible pipe), 12 ... Elementary pipe part, 14 ... Flare processing part, 20 ... Flexible part, 22 ... Mountain part, 24 ... Valley part, 40 ... Flexible wound by coil shape Pipe, d ... element pipe outer diameter, Dd ... mountain valley depth, P ... peak-to-peak pitch (pitch consisting of peak-top and peak-top), dt ... outer diameter after flaring, Dw ... Pitch from mountain to valley (pitch consisting of mountain top and valley bottom)

Claims

It is made of metal stainless steel with a thickness of 0.2 to 0.4 mm or less.
Having a flexible part with a corrugated shape;
When the outer diameter d (mm) of the raw tube is set, the corrugated shape is the outer diameter of the raw tube d / depth of the valley Dd: 15 to 23, and the outer diameter of the raw tube d / pitch from the peak portion to the peak portion. p: A stainless steel flexible tube characterized by satisfying 2.5 to 5.5.
The stainless steel flexible pipe according to claim 1, wherein the pipe has a pipe section at both ends or one end.
The stainless steel flexible tube according to claim 2, wherein the raw tube portion and the flexible portion having the corrugated shape are alternately arranged at a plurality of locations.
The stainless steel flexible tube according to any one of claims 1 to 3, wherein the entire flexible tube has a coil shape spirally swirled.
The stainless steel flexible pipe according to any one of claims 1 to 4, further comprising a raw pipe portion at both ends or one end, and further having a flared portion on both or one side of the raw pipe portion.