Pipelines for air conditioning systems

Abstract

A pipeline for an air conditioning system, comprising: a first pipe fitting (100) and a second pipe fitting (200), the second pipe fitting (200) being of a separate structure and including multiple stages of pipe bodies, the multiple stages of pipe bodies being arranged as a first pipe body (210) and at least one stage of a second pipe body (220), the first pipe body (210) and the first pipe fitting (100) being connected by furnace welding, and the second pipe body (220) and one end of the first pipe body (210) remote from the first pipe fitting (100) being connected by welding.

Description

【Technical Field】 【0001】 Related Applications This application claims the priority of a Chinese patent application with an application number of 202220158839.8 and an invention title of "Pipeline for Air Conditioning System", which was filed on January 20, 2022, and a Chinese patent application with an application number of 202210065987.X and an invention title of "Pipeline for Air Conditioning System", which was filed on January 20, 2022. All of its contents are incorporated into this application by reference. 【0002】 This application relates to the technical field of air conditioning systems, and particularly to pipelines for air conditioning systems. 【Background Art】 【0003】 In related art air conditioning systems, the communication of each pipeline element is realized by an air conditioning pipeline. The air conditioning pipeline mainly includes a pipeline body and other branch pipes connecting the air conditioning elements. However, since the pipeline body has a large volume and the branch pipes also have a relatively complex shape, the overall volume of the air conditioning pipeline is very large. It is difficult to assemble the pipeline body and the branch pipes, the assembly efficiency is low, and it is difficult to achieve automation. In addition, since the pipeline body occupies a large space, it is difficult to realize in-furnace welding, the welding efficiency is low, and the welding effect is poor. 【Summary of the Invention】 【0004】 According to various embodiments of this application, a pipeline for an air conditioning system with better assembly and welding effects is provided. 【0005】 The pipeline for an air conditioning system includes a first pipe joint and a second pipe joint. The second pipe joint has a split structure and includes a plurality of pipe sections. The plurality of pipe sections are arranged as a first pipe section and at least one second pipe section. Here, one end of the first pipe section is connected to the first pipe joint by in-furnace welding, and the other end of the first pipe section away from the first pipe joint is connected to the second pipe section by welding. 【0006】 In one embodiment, the first pipe joint and the first pipe body are joined by solder welding. In another embodiment, the first pipe body and the second pipe body are joined by self-sharpening welding or solder welding. Two adjacent second pipe bodies are joined by self-sharpening welding or solder welding. 【0007】 In one embodiment, the first pipe and the second pipe are connected using a slip-in method and then welded together. 【0008】 In one embodiment, an insertion portion is provided on one of the first and second pipe bodies, and a socket portion is provided on the other, and the insertion portion is inserted into the socket portion and welded. 【0009】 In one embodiment, a limiting structure is provided between the insertion portion and the socket portion to limit the insertion length between the first tube and the second tube. 【0010】 In one embodiment, the part of the first and second tubular bodies that has an insertion portion further includes a first main body and a first connecting portion, the first main body is connected to the insertion portion via the first connecting portion, the diameter of the insertion portion is smaller than the diameter of the first main body, and when the insertion portion is inserted into the socket portion, the first connecting portion stops the socket portion and forms a limiting structure. 【0011】 In one embodiment, the first and second tubular bodies, the one with the socket portion, further includes a second main body and a second connecting portion, the second main body being connected to the socket portion via the second connecting portion, the diameter of the socket portion being larger than the diameter of the second main body, and when the insertion portion is inserted into the socket portion, the second connecting portion stops the insertion portion and forms a limiting structure. 【0012】 In one embodiment, if the central axis of the welding torch nozzle is defined as l, the central axis of the socket is defined as b, and the angle between the central axis l and the central axis b of the socket is defined as α, then α must satisfy the relationship 10° ≤ α ≤ 60°. 【0013】 In one embodiment, the heat distribution ratio when the insertion part and the socket part are welded is 5:5 to 6:4. 【0014】 In one embodiment, the part of the first and second tubular bodies that has an insertion portion further includes a first main body, and a first restricting projection is provided between the first main body and the insertion portion, and the first restricting projection protrudes outward along the radial direction of the first main body, stopping the socket portion and forming a restricting structure. 【0015】 In one embodiment, the first and second tubes, the one with the socket portion, further includes a second main body, and a second restricting projection is provided between the second main body and the socket portion. The second restricting projection protrudes inward along the radial direction of the second main body, and the second restricting projection stops the insertion portion, forming a restricting structure. 【0016】 In one embodiment, if the diameter of the second pipe joint is defined as d, then d satisfies the relationship d ≤ 30 mm; if the weld bead gap between the first and second pipe bodies is defined as δ, then δ satisfies the relationship δ ≤ 0.05 mm; if the wall thickness of the second pipe joint is defined as t, then t satisfies the relationship t ≤ 1.5 mm; after the first and second pipe bodies are connected by a slip-in method, the deviation value of the concentricity between the first and second pipe bodies is 0.15 mm or less; and after the first and second pipe bodies are welded, the amount by which the wall thickness t of the second pipe joint decreases is 1% or less. 【0017】 In one embodiment, the first pipe and the second pipe are connected using a butt joint method and then welded together. 【0018】 In one embodiment, the first pipe fitting includes a copper pipe, a steel pipe, or an aluminum pipe. In another embodiment, the second pipe fitting includes a copper pipe, a steel pipe, or an aluminum pipe. 【0019】 In one embodiment, the first pipe and the second pipe are connected using a butt joint method and then welded, or connected using a slip-in method and then welded. In another embodiment, two adjacent second pipes are connected using a butt joint method and then welded, or connected using a slip-in method and then welded. 【0020】 Details of one or more embodiments of this application are presented in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. 【Brief Description of the Drawings】 【0021】 To better describe and explain the embodiments and / or examples of these inventions disclosed herein, one or more drawings can be referred to. Additional details or examples used to explain the drawings should not be considered as limiting the scope of any of the disclosed inventions, the embodiments and / or examples described herein, and the optimal forms of these inventions understood herein. 【0022】 [Figure 1] It is a schematic diagram of a partial cross-sectional structure of a pipeline for an air conditioning system provided by this application. [Figure 2] It is a schematic exploded view of a partial cross-section of a pipeline for an air conditioning system provided by this application. [Figure 3] It is a schematic assembly diagram of a first pipe body and a second pipe body in one embodiment of this application. [Figure 4] It is a schematic assembly diagram of a first pipe body and a second pipe body in one embodiment of this application. [Figure 5] It is a schematic assembly diagram of a first pipe body and a second pipe body in one embodiment of this application. [Figure 6] It is a schematic assembly diagram of a first pipe body and a second pipe body in one embodiment of this application. [Figure 7] It is a schematic assembly diagram of a first pipe body and a second pipe body in one embodiment of this application. [Figure 8] It is a schematic assembly diagram of a first pipe body and a second pipe body in one embodiment of this application. [Figure 9] It is a schematic assembly diagram of a first pipe body and a second pipe body in one embodiment of this application. [Figure 10] It is a schematic enlarged partial view of part A in FIG. 9. [Figure 11]It is an assembly schematic diagram of a first pipe body and a second pipe body in an embodiment of the present application. 【0023】 100 First pipe joint, 200 Second pipe joint, 210 First pipe body, 211 First main body part, 212 Insertion part, 213 First connection part, 214 First limiting protrusion, 220 Second pipe body, 221 Second main body part, 222 Socket part, 223 Second connection part, 224 Second limiting protrusion, l Central axis of the welding torch nozzle, b Central axis of the socket part, d Diameter of the second pipe joint, δ Welding bead gap of the second pipe body, t Wall thickness of the second pipe joint. 【Embodiments for Carrying out the Invention】 【0024】 In order to make the above objects, features, and advantages of the present application clearer and easier to understand, the following will refer to the drawings to explain the specific embodiments of the present application in detail. In the following description, various specific details are described to make the present application easier to understand. However, the present application can be implemented in many other aspects different from those described here, and those skilled in the art can make similar improvements as long as they do not violate the content of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below. 【0025】 It should be noted that when an assembly is said to be "fixed" or "provided" to another assembly, it may be directly fixed to the other assembly, or there may be intervening assemblies. When an assembly is considered to be "connected" to another assembly, it may be directly connected to the other assembly, or intervening assemblies may exist simultaneously. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in the specification of the present application are for illustrative purposes only and do not represent the only embodiment. 【0026】 Furthermore, the terms “first” and “second” are for descriptive purposes only and should not be understood as indicating or implying relative importance, or implicitly specifying the number of technical features described. Thus, features limited by “first” and “second” may either explicitly or implicitly include at least one of those features. In the description of this application, “multiple” means at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited. 【0027】 In this application, unless otherwise specifically stated or limited, the presence of a first feature "above" or "below" a second feature may mean that the first and second features are in direct contact, or that they are indirectly in contact through an intermediate medium. Furthermore, the presence of a first feature "above," "above," and "upper side" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply that the horizontal height of the first feature is greater than that of the second feature. The presence of a first feature "below," "below," and "below side" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply that the horizontal height of the first feature is lower than that of the second feature. 【0028】 Unless otherwise defined, all technical and scientific terms used in the specification of this application have the same meaning as that commonly understood by those skilled in the art. Terms used in the specification of this application are for the purpose of describing specific embodiments and are not intended to limit this application. The terms “and / or” used in the specification of this application include any and all combinations of the relevant enumerated items, one or more. 【0029】 The pipeline for the air conditioning system of this application will be described in more detail below with reference to the drawings and specific embodiments. 【0030】 Pipelines for air conditioning systems are used in air conditioning systems to ensure communication between each air conditioning element. A pipeline typically includes a main pipeline body and branch lines, which are pre-branched from the main pipeline body to connect to the air conditioning elements. Conventional pipeline fabrication usually involves full furnace welding. However, because the main pipeline body has a large volume and the branch pipes have relatively complex shapes, the overall volume of the air conditioning pipeline is very large, making assembly of the main pipeline body and branch pipes difficult, occupying a large space, making furnace welding difficult, and resulting in poor welding performance. 【0031】 To overcome the problems of the prior art, referring to Figures 1 and 2, according to one embodiment of the present application, the pipeline includes a first pipe joint 100 and a second pipe joint 200, the second pipe joint 200 forming the pipeline body and the first pipe joint 100 forming a branch line connected to an air conditioning element. The second pipe joint 200 has a separate structure and includes multiple stages of pipe, the multiple stages of pipe are arranged as a first pipe 210 and at least one stage of second pipe 220, the first pipe 210 and the first pipe joint 100 are connected by furnace welding, and the second pipe 220 and one end of the first pipe 210 away from the first pipe joint 100 are connected by welding. 【0032】 In this embodiment, after the second pipe joint 200 is divided into the first pipe body 210 and at least one stage of the second pipe body 220, the length and volume of each pipe body are reduced, and only the first pipe body 210 and the first pipe joint 100 need to be welded in the furnace, while the other pipe bodies do not need to be welded in the furnace. Since the volume and occupied space of the first pipe body 210 and the first pipe joint 100 become smaller after connection, furnace welding can be easily achieved, improving welding efficiency and welding effect. 【0033】 In this embodiment, the pipeline is divided and each section is welded before the entire pipeline is welded together, making it easier to automate the installation process. At the same time, since the lengths of the first pipe joint 100, the first pipe section 210, and the second pipe section 220 are all shortened after division, adjacent pipe joints or pipe sections can be assembled more easily, and the concentricity after assembly is also higher, thus improving assembly efficiency and effectiveness. 【0034】 The first pipe fitting 100 and the second pipe fitting 200 are usually made of metal pipes. The first pipe fitting 100 may be made of copper, steel, or aluminum pipe, and the second pipe fitting 200 may also be made of copper, steel, or aluminum pipe. In some embodiments, the first pipe fitting 100 is made of copper pipe. In some embodiments, the first pipe fitting 100 is made of phosphorus-deoxidized copper pipe (TP2) or pure copper pipe (T2). In some embodiments, the second pipe fitting 200 is made of steel pipe. In some embodiments, the second pipe fitting 200 is made of stainless steel pipe or carbon steel pipe. In some embodiments, the second pipe fitting 200 is made of stainless steel pipe, and typically stainless steel materials such as SUS304, SUS304L, SUS430L, SUS316, and SUS316L are used. 【0035】 The first pipe joint 100 and the first pipe body 210, the first pipe body 210 and the second pipe body 220, and two adjacent second pipe bodies 220 are connected and assembled, and then welded. 【0036】 The connection method between the first pipe fitting 100 and the first pipe body 210, the first pipe body 210 and the second pipe body 220, and two adjacent second pipe bodies 220 may be butt joint or slip-on joint, and in some embodiments, the connection method is slip-on joint. The welding method is self-sharpening or solder welding, and includes welding methods such as argon arc welding, laser welding, gas shielded arc welding, flame brazing, and high-frequency welding. In some embodiments, the first pipe fitting 100 and the first pipe body 210 are solder-welded. In some embodiments, the first pipe body 210 and the second pipe body 220, and two adjacent second pipe bodies 220 are self-sharpened. That is, the assembly configuration of the first pipe body 210 and the second pipe body 220, and two adjacent second pipe bodies 220 is slip-on joint followed by self-sharpening. 【0037】 For the sake of clarity, the assembly method of the first pipe 210 and the second pipe 220 will be explained in detail below as an example. 【0038】 As shown in Figures 3 to 9, the first pipe body 210 includes a first main body portion 211 and an insertion portion 212, and the second pipe body 220 includes a second main body portion 221 and a socket portion 222. The inner diameter of the socket portion 222 is larger than the outer diameter of the insertion portion 212, and a weld bead is formed so that the insertion portion 212 can be attached to the socket portion 222, and welding is performed at the weld bead. 【0039】 A limiting structure is provided between the insertion portion 212 and the socket portion 222 to control the insertion length between the first pipe body 210 and the second pipe body 220. 【0040】 In other embodiments, the insertion portion 212 may be provided on the second pipe body 220, and the socket portion 222 may be provided on the first pipe body 210. 【0041】 To achieve the restriction, as shown in Figure 3, according to one embodiment of the present application, the first pipe body 210 further includes a first connecting portion 213, and the first main body portion 211 is connected to the insertion portion 212 via the first connecting portion 213, the diameter of the insertion portion 212 is smaller than the diameter of the first main body portion 211, that is, the distance between the first connecting portion 213 and the central axis of the first pipe body 210 gradually decreases in the direction from the first main body portion 211 to the insertion portion 212, and to facilitate manufacturing, the socket portion 222 and the second main body portion 221 have the same diameter and are integrally molded. When the insertion portion 212 is inserted into the socket portion 222, the first connecting portion 213 stops the socket portion 222 and forms the restriction structure described above. Specifically, the first pipe body 210 is provided with a diameter reduction structure, the second pipe body 220 has a straight pipe structure, and a diameter reduction limiting structure is formed between the first pipe body 210 and the second pipe body 220. 【0042】 In other embodiments, the reduced diameter structure may be provided in the second pipe 220, and the first pipe 210 may have a straight pipe structure. 【0043】 As shown in Figure 4, according to another embodiment of the present application, the second pipe 220 further includes a second connecting portion 223, and the second main body 221 is connected to a socket portion 222 via the second connecting portion 223, the diameter of the socket portion 222 being larger than the diameter of the second main body 221, that is, the distance between the second connecting portion 223 and the central axis of the second pipe 220 gradually increases in the direction from the second main body 221 to the socket portion 222, and to facilitate manufacturing, the insertion portion 212 and the first main body 211 have the same diameter and are integrally molded. When the insertion portion 212 is inserted into the socket portion 222, the second connecting portion 223 stops the insertion portion 212 and forms the above-mentioned limiting structure. That is, the second pipe 220 is provided with an expanding diameter structure, the first pipe 210 is a straight pipe structure, and an expanding diameter limiting structure is formed between the first pipe 210 and the second pipe 220. 【0044】 When the first pipe body 210 and the second pipe body 220 are assembled using the above-described diameter expansion limiting structure and then welded, the heat generated from the flame ejected from the welding torch nozzle extends along the axial direction of the welding torch nozzle toward the insertion portion 212, forming a heat-affected region in the insertion portion 212. As the angle between the central axis l of the welding torch nozzle and the central axis b of the socket portion 222 gradually widens, the welding torch nozzle increasingly faces the side wall of the insertion portion 212, and the possibility of the insertion portion 212 melting and leaking gradually increases. In order to prevent the insertion portion 212 from melting while ensuring a good welding effect, in this embodiment, the rotation angle of the welding torch is controlled so that the angle α between the extension of the central axis l of the welding torch nozzle and the central axis b of the socket portion satisfies 10° ≤ α ≤ 60°. 【0045】 It goes without saying that in other welding methods as well, the positional requirements between the welding torch nozzle and the pipe body must satisfy the above conditions, and therefore will not be explained in detail here. 【0046】 In the welding process, in order to ensure a good welding effect, a large amount of molten base material is needed in the socket portion 222. That is, the heat occupied by the external socket portion 222, which is closer to the welding source, must be greater than that occupied by the internal insertion portion 212. As a result, the tungsten needle of the welding torch is biased towards the socket portion 222 and moves away from the welding bead ring, resulting in a uniform and plump weld bead. In this embodiment, the heat distribution ratio when the insertion portion 212 and the socket portion 222 are welded is 5:5 to 6:4, and in some embodiments, the heat distribution ratio when the insertion portion 212 and the socket portion 222 are welded is 6:4. 【0047】 In other embodiments, it goes without saying that the diameter-enlarged structure may be provided in the first pipe body 210, and the second pipe body 220 may be a straight pipe structure. 【0048】 In other embodiments, it goes without saying that a diameter-expanding structure may be provided on one of the first tube 210 and the second tube 220, and a diameter-reducing structure may be provided on the other, thereby forming a double limiting structure. 【0049】 As shown in Figures 5 and 7, according to another embodiment of this application, the first pipe body 210 and the second pipe body 220 are connected using a straight-insert method, that is, the first main body portion 211 and the insertion portion 212 have the same diameter and are integrally molded, the second main body portion 221 and the socket portion 222 have the same diameter and are integrally molded, and a first limiting projection 214 is provided between the first main body portion 211 and the insertion portion 212, the first limiting projection 214 protrudes outward along the radial direction of the first main body portion 211, stopping the socket portion 222 and forming a limiting structure. As shown in Figure 5, the first limiting projection 214 may be an annular projection, and as shown in Figure 7, the first limiting projection 214 may be a plurality of bulges provided at intervals. In one embodiment, the plurality of bulges are evenly distributed along the circumferential direction of the first main body portion 211 so that the stopping force is evenly distributed along the circumferential direction and stress concentration is avoided. 【0050】 As shown in Figures 6 and 8, in other embodiments, a second limiting projection 224 may be provided between the second main body portion 221 and the socket portion 222, and the second limiting projection 224 may project inward along the radial direction of the second main body portion 221, stopping the insertion portion 212 and forming a limiting structure. As shown in Figure 6, the second limiting projection may be an annular projection, and as shown in Figure 8, the second limiting projection may be a plurality of bulges provided at intervals. In one embodiment, the plurality of bulges are evenly distributed along the circumferential direction of the second main body portion 221 so that the stopping force is evenly distributed along the circumferential direction and stress concentration is avoided. 【0051】 In other embodiments, as shown in Figures 9 and 10, the first pipe 210 and the second pipe 220 may be inserted in a straight line to an appropriate position without any restricting structure and then directly welded together. 【0052】 Needless to say, the above assembly method also applies to the two adjacent second pipe sections 220. 【0053】 It goes without saying that the above assembly method also applies to the first pipe joint 100 and the first pipe body 210. 【0054】 In this embodiment, the diameter of the second pipe joint 200 is defined as d, with d ≤ 30 mm; the weld bead gap between the first pipe body 210 and the second pipe body 220 is defined as δ, with δ ≤ 0.05 mm; the wall thickness of the second pipe joint 200 is defined as t, with t ≤ 1.5 mm; and when the above insertion connection method is used, the concentricity between the first pipe body 210 and the second pipe body 220 is good, the deviation value of the concentricity between the first pipe body 210 and the second pipe body 220 is 0.15 mm or less, the heat-affected zone of the pipe material after welding is within 5 mm near the weld bead, and assuming that the wall thickness of the heat-affected zone after welding is uniform, the amount by which the wall thickness t of the second pipe joint 200 is reduced in this application is: 【0055】 【number】 【0056】 Therefore, the amount by which the wall thickness t has decreased is less than 0.1, meaning that the strength of the welded area is high because the amount by which the wall thickness t has decreased is small. 【0057】 In other embodiments, as shown in Figure 11, the first pipe 210 and the second pipe 220 may be connected using a butt joint method and then welded. 【0058】 The technical features of the embodiments described above can be combined in any way, and for the sake of brevity, not all possible combinations of the technical features in the embodiments described above have been explained. However, as long as these combinations of technical features are inconsistent, they should all be considered to fall within the scope described herein. 【0059】 The embodiments described above are merely examples of some embodiments of this application, and although their descriptions are relatively specific and detailed, they should not be understood as limiting the scope of the claims of this application. Those skilled in the art may make several modifications and improvements, provided they do not depart from the spirit of this application, and it should be noted that all of these fall within the scope of protection of this application. Therefore, the scope of protection of the patent of this application shall be in accordance with the attached claims.

Claims

[Claim 1] First pipe fitting and, A second pipe joint having a separate structure and including multiple stages of tubular bodies, wherein the multiple stages of tubular bodies are arranged as a first tubular body and at least one stage of second tubular bodies, Includes, One end of the first pipe body and the first pipe joint are connected by furnace welding, and the other end of the first pipe body, away from the first pipe joint, is connected to the second pipe body by welding. The first pipe and the second pipe are connected using a slip-in method and then welded together. An insertion portion is provided on one of the first and second pipe bodies, and a socket portion having a larger diameter than the insertion portion is provided on the other, and the insertion portion is inserted into the socket portion and welded. If we define the central axis of the welding torch nozzle as l, the central axis of the socket as b, and the angle between the central axis l of the welding torch nozzle and the central axis b of the socket as α, then α must satisfy the relationship 10° ≤ α ≤ 60°. The heat distribution ratio when the insertion part is inserted into the socket part and the insertion part and the socket part are welded together is 5:5 to 6:

4. Pipelines for air conditioning systems. [Claim 2] The pipeline for an air conditioning system according to claim 1, wherein the first pipe joint and the first pipe body are joined by solder welding, or the first pipe body and the second pipe body are joined by self-sharpening or solder welding, or two adjacent second pipe bodies are joined by self-sharpening or solder welding. [Claim 3] A limiting structure is provided between the insertion portion and the socket portion to limit the insertion length between the first pipe and the second pipe, as described in claim 1, for an air conditioning system pipeline. [Claim 4] The pipe for an air conditioning system according to claim 3, wherein the part of the first pipe and the second pipe provided with the insertion portion further includes a first main body and a first connecting portion, the first main body is connected to the insertion portion via the first connecting portion, the diameter of the insertion portion is smaller than the diameter of the first main body, and when the insertion portion is inserted into the socket portion, the first connecting portion stops the socket portion and forms the limiting structure. [Claim 5] The pipe for an air conditioning system according to claim 3, wherein the first pipe and the second pipe provided with the socket portion further include a second main body and a second connecting portion, the second main body is connected to the socket portion via the second connecting portion, the diameter of the socket portion is larger than the diameter of the second main body, and when the insertion portion is inserted into the socket portion, the second connecting portion stops the insertion portion and forms the limiting structure. [Claim 6] The pipe for an air conditioning system according to claim 3, wherein the part of the first pipe and the second pipe on which the insertion portion is provided further includes a first main body, a first limiting projection is provided between the first main body and the insertion portion, the first limiting projection protrudes outward along the radial direction of the first main body, stops the socket portion and forms the limiting structure. [Claim 7] The pipe for an air conditioning system according to claim 3, wherein the first pipe and the second pipe, the one on which the socket portion is provided, further include a second main body, a second limiting projection is provided between the second main body and the socket portion, the second limiting projection protrudes inward along the radial direction of the second main body, stops the insertion portion, and forms the limiting structure. [Claim 8] The pipeline for an air conditioning system according to claim 1, wherein the diameter of the second pipe joint is defined as d, so that d ≤ 30 mm; the weld bead gap between the first pipe and the second pipe is defined as δ, so that δ ≤ 0.05 mm; the wall thickness of the second pipe joint is defined as t, so that t ≤ 1.5 mm; after the first pipe and the second pipe are connected by a slip-in method, the deviation value of the concentricity between the first pipe and the second pipe is 0.15 mm or less; and after the first pipe and the second pipe are welded together, the amount by which the wall thickness t of the second pipe joint decreases is 1% or less. [Claim 9] The pipeline for an air conditioning system according to claim 1, wherein the first pipe fitting includes a copper pipe, a steel pipe, or an aluminum pipe, or the second pipe fitting includes a copper pipe, a steel pipe, or an aluminum pipe. [Claim 10] The first pipe and the second pipe are connected using a butt joint method and then welded, or connected using a slip-in method and then welded. The pipeline for an air conditioning system according to claim 1, wherein two adjacent second pipes are connected using a butt joint method and then welded, or connected using a slip-in method and then welded.

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