A connecting joint for nitrogen purging of metal pipes

Abstract

The present invention relates to the technical field of connection structures, and particularly to a connection joint for purging metal pipes with nitrogen, which includes an outer pipe. One end of the outer pipe is provided with a clamping structure for fixing the metal pipe, and the other end of the outer pipe is used for connecting to a gas source. A piston is slidably arranged in the outer pipe, and a gas hole for gas to flow through is formed in the middle of the piston. Therefore, air pressure can produce a direct and effective pushing effect on the piston, so that the piston moves within a small range in the outer pipe and fits more closely with the end of the metal pipe, improving the sealing performance of the connection between the joint and the metal pipe. Moreover, this connection method is simple and fast, capable of realizing a quick installation working mode, so that it can be applied to the rapid purging work of multiple metal pipes. At the same time, since the gas hole is directly connected to the metal pipe, there is no limitation on the diameter of the metal pipe, facilitating the rapid connection and nitrogen purging work of metal pipes of different models and specifications.

Description

Technical Field

[0001] The present invention relates to the technical field of connection structures, and particularly to a connection joint for nitrogen purging of metal pipes. Background Art

[0002] During the manufacturing and processing of metal pipes, nitrogen purging technology is widely used to remove impurities, oxides, and residual gases inside the pipes to ensure the cleanliness and performance of the pipes. Especially during the welding, heat treatment, or surface treatment of metal pipes such as stainless steel, copper, and aluminum, nitrogen purging can effectively prevent oxidation and improve product quality.

[0003] During the actual operation process, achieving efficient nitrogen purging not only depends on the quality and pressure of nitrogen, but also requires appropriate equipment and accessories to ensure the smooth progress of the entire process. Among them, as one of the key components in the nitrogen purging system, the rationality of the design of the connection joint directly affects the purging efficiency and operation safety.

[0004] Traditional connection joints need to use different models of connection joints according to the outer diameter or inner diameter of different metal pipes during use. Therefore, the applicability of the connection joints is poor. And when the joint is docked with the metal pipe, a single-sided conical or double-sided conical sealing ring needs to be sleeved on the outer wall of the metal pipe, and then the conical surface of the sealing ring is squeezed along the axial direction of the metal pipe by means of screwing, so that the joint and the metal pipe are hermetically connected. However, due to the relatively high pressure of nitrogen purging, leakage often occurs, resulting in waste of nitrogen resources, and its operation method is cumbersome and not suitable for continuous disassembly, assembly, and nitrogen purging of multiple metal pipes. Summary of the Invention

[0005] The present invention provides a connection joint for nitrogen purging of metal pipes, which can effectively solve the problems in the background art.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A connection joint for nitrogen purging of metal pipes includes an outer pipe. One end of the outer pipe is provided with a clamping structure for fixing the metal pipe, and the other end of the outer pipe is used for connecting with a gas source;

[0008] A piston is slidably arranged inside the outer pipe. A gas hole for gas to flow through is opened in the middle of the piston. A plurality of sealing rings for sealing are arranged on the circumferential outer wall of the piston. At least during a partial stroke of the piston movement, the piston abuts against the end of the metal pipe.

[0009] In some embodiments of the present invention, a cone barrel is arranged on the side wall of the piston along the gas flow direction inside the outer pipe.

[0010] In some embodiments of the present invention, a sealing sleeve having the same shape as the conical cylinder is provided on the outer wall of the conical cylinder.

[0011] In some embodiments of the present invention, a cavity having the same shape as the sealing sleeve is provided inside the sealing sleeve.

[0012] In some embodiments of the present invention, a spring is provided inside the outer tube, and the spring is sleeved outside the conical cylinder. One end of the spring contacts the side wall of the piston, and the other end of the spring is installed on the inner wall of the outer tube through a connecting ring and a snap ring.

[0013] In some embodiments of the present invention, the spring is in surface contact with the side wall of the piston.

[0014] In some embodiments of the present invention, the outer tube includes a thick tube and a thin tube, the thick tube and the thin tube are integrally formed, the piston is located inside the thick tube, the clamping structure is installed on the thick tube, and the spring provides an elastic thrust for the piston and makes the side wall of the piston fit against the stepped position between the thick tube and the thin tube.

[0015] In some embodiments of the present invention, the clamping structure includes a base ring and a plurality of movable arms slidably installed on the base ring. A pressing plate for pressing the metal tube is provided at the end of the movable arm. A power ring is rotatably provided on the base ring. Helical teeth are provided on the side wall of the power ring and the side walls of each of the movable arms, and the power ring and each of the movable arms are meshed and connected through the helical teeth.

[0016] In some embodiments of the present invention, the linear direction of the movable arm is a direction inclined towards the thin tube or a direction perpendicular to the axis of the base ring.

[0017] In some embodiments of the present invention, the linear direction of the movable arm is perpendicular to the axis of the base ring, the pressing plate slides relative to the movable arm, and the sliding direction of the pressing plate on the movable arm is inclined along the direction of the airflow inside the outer tube. The pressing plate and the movable arm are connected through an elastic sheet.

[0018] Through the technical solution of the present invention, the following technical effects can be achieved:

[0019] By using the nitrogen gas pressure to generate a lateral thrust on the piston, the piston is closely attached to the end of the metal tube, thereby effectively improving the sealing effect, facilitating the realization of the function that the stronger the air pressure, the better the sealing effect, and its sealing method is simple, the disassembly and assembly are convenient and fast, and it can be applied to the rapid connection of different metal tubes and the nitrogen purging work. At the same time, since only the air hole needs to be communicated with the metal tube to realize nitrogen purging, the joint can be applied to metal tubes of different calibers or models, and its applicability is better. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 is a schematic structural diagram of the present invention;

[0022] Figure 2 is a schematic diagram of the inner structure of the outer tube in an embodiment of the present invention;

[0023] Figure 3 is a schematic cross-sectional structural diagram of the piston in an embodiment of the present invention;

[0024] Figure 4 is a schematic structural diagram of the clamping structure in an embodiment of the present invention;

[0025] Figure 5 is Figure 4 a schematic structural diagram of another perspective;

[0026] Figure 6 is a schematic structural diagram of the movable arm in an embodiment of the present invention.

[0027] Reference numerals:

[0028] 100, outer tube; 101, piston; 102, air hole; 103, sealing ring; 104, conical tube; 105, sealing sleeve; 106, pressing ring; 107, cavity; 108, spring; 109, connecting ring; 110, snap ring; 111, thick tube; 112, thin tube;

[0029] 200, clamping structure; 201, base ring; 202, movable arm; 203, pressing plate; 204, power ring; 205, handle; 206, elastic piece. Detailed implementation manners

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the specification of this invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0032] As Figures 1 to 3 shown, a connecting joint for nitrogen purging of a metal tube according to the present invention includes an outer tube 100. One end of the outer tube 100 is provided with a clamping structure 200 for fixing the metal tube, and the other end of the outer tube 100 is used for connection with a gas source.

[0033] A piston 101 is slidably disposed in the outer tube 100. A gas hole 102 for gas flow is formed in the middle of the piston 101. A plurality of sealing rings 103 for sealing are disposed on the circumferential outer wall of the piston 101. At least during a partial stroke of the movement of the piston 101, the piston 101 abuts against the end of the metal tube.

[0034] In the present invention, the clamping structure 200 provided at one end of the outer tube 100 can squeeze and fix the metal tube inserted into the outer tube 100, and the other end of the outer tube 100 needs to be connected to a gas source. In this way, the nitrogen provided by the gas source can be transported into the metal tube through the outer tube 100. The connection between the outer tube 100 and the gas source can be realized by screwing the threaded pipe as the output end on the gas source and the thread provided on the inner wall of the outer tube 100 to be tightened, or by installing structures such as flanges and sealing rings for connecting with the gas pipe at the end of the outer tube 100. Since there is no need to frequently disassemble and assemble between the outer tube 100 and the gas source, only a conventional connection method can be adopted; of course, in some embodiments, a quick-install form or structure can also be used to realize the connection; the piston 101 in the outer tube 100 is allowed to move along the axis direction of the outer tube 100 in the outer tube 100, and the plurality of sealing rings 103 on the outer wall of the piston 101 are mainly used to improve the sealing effect between the piston 101 and the inner wall of the outer tube 100 to facilitate the sealed movement of the piston 101;

[0035] During use, the end of the metal tube passes through the clamping structure 200 and is inserted into the outer tube 100. The side wall of the piston 101 abuts against the end of the metal tube, and the air hole 102 communicates with the metal tube. The clamping structure 200 clamps and fixes the metal tube. When nitrogen purging is required, the gas source releases nitrogen and introduces it into the outer tube 100. The air pressure in the outer tube 100 increases, and the nitrogen inside it is introduced into the metal tube through the air hole 102. Since there is a relatively high air pressure in the outer tube 100 and the contact area between the side wall of the piston 101 and the nitrogen is large, the air pressure can directly and effectively push the piston 101. As a result, the piston 101 moves a small distance inside the outer tube 100 and fits more closely with the end of the metal tube, improving the sealing performance of the connection between the joint and the metal tube. Moreover, this connection method is simple and fast, enabling a quick installation working mode, so it can be applied to the rapid purging of multiple metal tubes. At the same time, since the air hole 102 is directly docked with the metal tube, there is no restriction on the diameter of the metal tube, facilitating the quick connection and nitrogen purging of metal tubes of different models and specifications;

[0036] In some embodiments, to enhance the fitting effect between the piston 101 and the metal tube, auxiliary structures can be added, such as a sealing gasket, an elastic structure that provides elastic thrust to the piston 101, etc. Regarding the diameter of the air hole 102, since air pressure is required to generate thrust on the piston 101, the diameter of the air hole 102 is at most half of the diameter of the piston 101.

[0037] Optimized based on the above implementation, such as Figure 3 As shown, a conical cylinder 104 is provided on the side wall of the piston 101 along the gas flow direction inside the outer tube 100.

[0038] One side of the piston 101 faces the gas flow direction inside the outer tube 100, and this side of the piston 101 is mainly used for gas propulsion. A conical cylinder 104 is provided at the other end of the piston 101, and the conical cylinder 104 is docked and communicated with the air hole 102. When docking with the metal tube, the end of the metal tube is sleeved on the conical surface of the conical cylinder 104. In this way, part of the conical cylinder 104 will be inside the metal tube, and the remaining part of the conical cylinder 104 will be outside the metal tube, thereby realizing the docking and communication work between the piston 101 and the metal tube. This method can prevent the relative sliding and displacement deviation between the metal tube and the piston 101, and at the same time ensure that the air hole 102 can communicate with the metal tube, avoiding gas leakage when the air hole 102 is misaligned with the metal tube. At the same time, when the air pressure generates a driving force on the piston 101, the force received by the conical cylinder 104 will tend to have a flaring effect on the end of the metal tube, thereby further improving the sealing performance between the joint and the metal tube; it should be noted that the conical cylinder 104 can also be applied to metal tubes of different diameters;

[0039] In some embodiments, if the metal tube is of a special shape such as a polygon, the shape of the conical cylinder 104 also needs to be adjusted accordingly to correspond to the shape of the metal tube; the piston 101 and the conical cylinder 104 can be processed by integral molding or made by welding connection.

[0040] Optimized based on the above implementation, such as Figure 3 As shown, a sealing sleeve 105 having the same shape as the conical cylinder 104 is provided on the outer wall of the conical cylinder 104.

[0041] In the present invention, the shape of the sealing sleeve 105 is the same as that of the conical cylinder 104, and they are both conical. In this way, when the end of the metal tube is abutted and sleeved on the outer wall of the sealing sleeve 105, the abutting and communicating work with the conical cylinder 104 or the piston 101 can be realized. The setting of the sealing sleeve 105 can enhance the sealing effect between the joint and the metal tube;

[0042] Since the sealing sleeve 105 is also conical, it can be directly sleeved on the conical cylinder 104 during installation, and a pressing ring 106 can be installed at the end of the conical cylinder 104 to block the sealing sleeve 105 and make the sealing sleeve 105 firmly installed on the conical cylinder 104; to improve the contact tightness between the sealing sleeve 105 and the end of the metal tube, a number of stepped structures can be provided on the outer wall of the sealing sleeve 105, and the end of the metal tube is directly sleeved on the steps. In this way, the sealing sleeve 105 can achieve a good contact sealing effect on both the end face and the inner wall of the metal tube.

[0043] Optimized based on the above implementation, such as Figure 3 As shown, a cavity 107 having the same shape as the outer shape of the sealing sleeve 105 is opened inside the sealing sleeve 105.

[0044] The cavity 107 can be filled with gas or fluid. When the end of the metal tube contacts a partial area of the outer wall of the sealing sleeve 105, the end face of the metal tube will push the area of the sealing sleeve 105 to sink into the cavity 107, and the sealing sleeve 105 will undergo local deformation. The space of a partial cavity 107 corresponding to the sunken position of the sealing sleeve 105 becomes smaller, and thus the air or fluid is squeezed to the left and right sides of the cavity 107. Bulging deformations will occur on the left and right sides of the contact position between the sealing sleeve 105 and the metal tube. Thus, it is convenient to make the outer wall of the deformed part of the sealing sleeve 105 contact with the end face or the inner wall of the metal tube, thereby improving the sealing performance for the metal tube;

[0045] It should be noted that since the outer wall of the sealing sleeve 105 only needs to be in contact with the metal tube, the outer wall of the sealing sleeve 105 can be set as a smooth surface. In this way, when the end of the metal tube contacts any position of the outer wall of the sealing sleeve 105, it can strengthen the sealing effect of the metal tube. Even if the metal tube and the sealing sleeve 105 are not coaxial and the assembly accuracy of the sealing sleeve 105 and the metal tube is low, this effect can still be achieved. Of course, in this case, the deviation distance between the metal tube and the sealing sleeve 105 should not be too large, otherwise the connection effect cannot be achieved;

[0046] When the sealing sleeve 105 is actually processed, a rubber layer can be formed on the surface of a long plate-shaped core material. When the long plate is pulled out, a flat long tube structure will be left, and then the two ends of the long tube are melted and butt-jointed to form the shape of the sealing sleeve 105 used in this case.

[0047] Optimized from the above implementation, such as Figure 2 As shown, a spring 108 is arranged inside the outer tube 100, and the spring 108 is sleeved outside the conical tube 104. One end of the spring 108 contacts the side wall of the piston 101, and the other end of the spring 108 is installed on the inner wall of the outer tube 100 through a connecting ring 109 and a circlip 110.

[0048] In the present invention, one end of the spring 108 is connected to the side wall of the piston 101, and the other end of the spring 108 is connected to the connecting ring 109. The specific connection method can be any method such as welding, abutting, riveting, etc. The circlip 110 realizes the clamping and fixing effect on the connecting ring 109, so that the spring 108, the connecting ring 109 and the circlip 110 are installed in the outer tube 100; when connecting the metal tube, the end of the metal tube can abut against the sealing sleeve 105, and the metal tube can be inserted more into the outer tube 100. In this way, the metal tube will generate a thrust on the piston 101, so that the spring 108 undergoes elastic deformation, and the spring 108 generates a moving pulling force on the piston 101, so that there is a certain extrusion force between the piston 101 and the metal tube, which is convenient for preventing gas leakage in the initial state of gas supply.

[0049] Optimized from the above implementation, the spring 108 and the side wall of the piston 101 are in a surface contact state.

[0050] Since the spring 108 provides an elastic force for the piston 101, when the spring 108 is in a point contact mode with the piston 101, the force exerted by the spring 108 on the piston 101 will cause the piston 101 to be unevenly stressed. Some of the sealing rings 103 on one side of the piston 101 will be deformed more severely, while some of the sealing rings 103 on the other side of the piston 101 will have less deformation. This will cause gas leakage, and the friction between the piston 101 and the inner wall of the outer tube 100 will increase, making it difficult for the piston 101 to move. By making the spring 108 in a surface contact state with the piston 101, the above problems can be effectively avoided; it should be noted that the surface contact state can be achieved by installing a gasket or other support structure at the end of the spring 108, or by grinding the end of the spring 108 flat, or by tightening the end of the spring 108 to form a flat support surface. As long as the effects of this case can be achieved, they are within the protection scope of this case.

[0051] Optimized based on the above implementation, as Figure 1 shown, the outer tube 100 includes a thick tube 111 and a thin tube 112. The thick tube 111 and the thin tube 112 are integrally formed. The piston 101 is located inside the thick tube 111. The clamping structure 200 is installed on the thick tube 111. The spring 108 provides an elastic thrust for the piston 101 and makes the side wall of the piston 101 fit against the stepped position between the thick tube 111 and the thin tube 112.

[0052] In the present invention, one end of the thin tube 112 is butt - joined with the thick tube 111. The other end of the thin tube 112 can be provided with structures such as a flange or an internal thread to achieve its connection work with the gas source. The clamping structure 200 can be installed on the thick tube 111 by means of bolts or clamping. The piston 101 and its upper structures are all installed inside the thick tube 111. And a groove for installing a snap ring 110 is provided on the inner wall of the thick tube 111. This structural form can facilitate the assembly work of the joint and the processing of the joint. The stepped position between the thick tube 111 and the thin tube 112 can be used to block and position the piston 101, thus preventing the piston 101 from moving randomly inside the outer tube 100. The spring 108 can provide a pre - tightening thrust for the piston 101;

[0053] It should be noted that the thick tube 111 and the thin tube 112 can be integrally formed or processed by welding.

[0054] Optimized based on the above implementation, as Figures 4 to 5 shown, the clamping structure 200 includes a base ring 201 and a number of movable arms 202 slidably installed on the base ring 201. The end of the movable arm 202 is provided with a pressing plate 203 for extruding the metal tube. A power ring 204 is rotatably arranged on the base ring 201. Helical teeth are provided on the side wall of the power ring 204 and the side walls of each movable arm 202. The power ring 204 and each movable arm 202 are meshed and connected through the helical teeth.

[0055] In the present invention, the base ring 201 can be installed on the thick pipe 111 by means of bolts. The base ring 201 is coaxial with the thick pipe 111. When connecting a metal pipe, the metal pipe passes through the base ring 201 and extends into the thick pipe 111. By rotating the power ring 204, using helical teeth, multiple movable arms 202 are synchronously moved closer to each other. The multiple movable arms 202 push the multiple pressing plates 203 to move synchronously and perform an extrusion and clamping process on the metal pipe, thereby realizing the fixing work of the metal pipe; the positions of the multiple movable arms 202 are relatively distributed on the base ring 201, that is, the multiple pressing plates 203 are allowed to contact the metal pipe simultaneously to realize the centering work of the metal pipe; the setting of the power ring 204 can realize the synchronous movement of the multiple movable arms 202, and the operator only needs to control the power ring 204 to realize the control work of the multiple movable arms 202 and the multiple pressing plates 203, so the operation is simpler; the working surface of the pressing plate 203 can be an arc surface that matches the outer wall of the metal pipe, or a rubber pad is arranged on the working surface of the pressing plate 203 to achieve the surface contact effect between the pressing plate 203 and the metal pipe, and it is convenient to increase the friction force and can be used for metal pipes with different radii;

[0056] In some embodiments, a handle 205 can be arranged on the power ring 204 for convenient operation. The handle 205 can also be used as a setscrew structure and is threadedly connected to the power ring 204. When it is necessary to rotate the power ring 204, the worker only needs to push the handle 205 to move. When the metal pipe is clamped, only the handle 205 needs to be screwed so that the handle 205 abuts against the outer wall of the base ring 201, thereby locking the position of the power ring 204.

[0057] Optimized based on the above implementation, the linear direction where the movable arm 202 is located is a direction inclined towards the thin pipe 112 or a direction perpendicular to the axis of the base ring 201.

[0058] In the present invention, the moving direction of the movable arm 202 is the linear direction where it is located. The movable arm 202 can allow inclined movement or movement along the radial direction of the base ring 201, and in this way, the working effect that the pressing plate 203 approaches or moves away from the axis of the base ring 201 can be realized; for the inclined movement of the movable arm 202, it needs to be inclined towards the direction of the thin pipe 112, so that the movable arm 202 will have a conflicting effect with the nitrogen flow direction, thereby improving the clamping effect; Figure 5 For example, when the movable arm 202 is along the radial direction of the base ring 201, this setting method can make the multiple pressing plates 203 move perpendicularly towards the axis direction of the base ring 201, and the helical teeth on the movable arm 202 and the power ring 204 can coincide with the vertical plane, so that the processing of the helical teeth is simpler and more convenient.

[0059] Optimized based on the above implementation, such as Figures 5 to 6As shown, the direction of the straight line where the movable arm 202 is located is perpendicular to the axis of the base ring 201. The pressure plate 203 slides relative to the movable arm 202, and the sliding direction of the pressure plate 203 on the movable arm 202 is inclined along the airflow direction inside the outer tube 100. The pressure plate 203 and the movable arm 202 are connected by an elastic sheet 206.

[0060] In the present invention, the elastic sheet 206 is mainly used to provide an elastic thrust for the pressure plate 203. When the movable arm 202 moves towards the metal tube, the movable arm 202 will push the pressure plate 203 to move synchronously through the elastic sheet 206, and the pressure plate 203 realizes the clamping and fixing of the metal tube. Since the pressure plate 203 slides obliquely on the movable arm 202, the force exerted by the movable arm 202 on the pressure plate 203 will cause the pressure plate 203 to have a moving tendency towards the capillary tube 112 on the metal tube, thereby improving the docking tightness between the metal tube and the piston 101. And when the piston 101 exerts a force on the metal tube along the airflow direction due to the influence of air pressure, due to the friction between the pressure plate 203 and the metal tube, the squeezing force of the pressure plate 203 on the metal tube can be made stronger, thereby realizing a more effective clamping effect of the clamping structure 200 on the metal tube by reversely utilizing the air pressure.

[0061] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A connecting joint for nitrogen purging of a metal pipe, characterized in that, It includes an outer tube, one end of the outer tube is provided with a clamping structure for fixing a metal tube, and the other end of the outer tube is used for connection with a gas source; A piston is slidably arranged in the outer tube. An air hole for gas flow is formed in the middle of the piston. A plurality of sealing rings for sealing are arranged on the circumferential outer wall of the piston. At least during a partial stroke of the piston movement, the piston abuts against the end of the metal tube; A spring is arranged in the outer tube, and the spring is sleeved outside the conical tube. One end of the spring contacts the side wall of the piston, and the other end of the spring is installed on the inner wall of the outer tube through a connecting ring and a snap ring; The spring is in a surface contact state with the side wall of the piston; The outer tube includes a thick tube and a thin tube which are integrally formed. The piston is located in the thick tube. The clamping structure is installed on the thick tube. The spring provides an elastic thrust for the piston and makes the side wall of the piston fit on the stepped position between the thick tube and the thin tube; A conical tube is arranged on the side wall of the piston along the gas flow direction in the outer tube; The clamping structure includes a base ring and a plurality of movable arms slidably installed on the base ring. A pressing plate for extruding the metal tube is arranged at the end of the movable arm. A power ring is rotatably arranged on the base ring. Helical teeth are arranged on the side wall of the power ring and the side walls of the movable arms. The power ring and the movable arms are meshed and connected through the helical teeth; The straight line direction of the movable arm is perpendicular to the axis of the base ring. The pressing plate slides relative to the movable arm, and the sliding direction of the pressing plate on the movable arm is inclined along the gas flow direction in the outer tube. The pressing plate and the movable arm are connected through an elastic sheet.

2. The connecting joint for nitrogen purging of a metal pipe according to claim 1, characterized in that, A sealing sleeve with the same shape as the conical tube is arranged on the outer wall of the conical tube; 3. The connecting joint for nitrogen purging of a metal pipe according to claim 2, characterized in that, A cavity with the same shape as the outer shape of the sealing sleeve is formed inside the sealing sleeve.

Images