A device and method for testing the gas tightness of a weld of a stainless steel tube

Abstract

The present application relates to gas tightness test technical field, especially to a kind of gas tightness test device and method at weld of stainless steel pipe, testing device includes sliding base, the top of the sliding base is provided with two outer frames, the center of two The outer frame is respectively fixedly connected with pressurizing assembly and pressure sensor, the outer wall of pressurizing assembly and pressure sensor is respectively rotationally connected with conductive rubber, the outer wall of two The conductive rubber is respectively fixedly installed with convex ring, the inner wall of two The outer frame is respectively fixedly installed with sealing ring, the inner portion of two The outer frame is respectively provided with liquid storage cavity, testing method includes preparation, sealing and filling etc. The present application utilizes magnetic fluid to close and fill gap, even if there is slight change in pipe diameter or surface unevenness, magnetic fluid can closely adhere to the surface of pipeline, form a tight sealing layer, magnetic fluid solidification can adapt to the shape of gap, increase the plugging effect of filling gap, ensure the accuracy of test.

Description

Technical Field

[0001] This invention relates to the field of gas tightness testing technology, and in particular to a gas tightness testing device and method for weld seams of stainless steel pipes. Background Technology

[0002] Gas tightness testing at the weld joints of stainless steel pipes is conducted to ensure that the welded area meets design requirements for sealing, preventing gas leakage and ensuring the safe, reliable, and efficient operation of the pipeline system. Gas tightness testing can also detect potential defects during the welding process, such as porosity and slag inclusions, helping to improve weld quality and avoid subsequent maintenance and repair work caused by sealing problems.

[0003] Currently, traditional testing equipment seals both ends of the pipe during testing. However, the pipe diameter may vary slightly or the surface may be uneven. Traditional sealing methods cannot tightly seal the pipe surface, resulting in poor sealing. Even if there is a small leak in the weld, it may not be detected due to poor sealing, thus affecting the accuracy of the test. It is difficult for inspectors to determine whether there is a leak in the weld, which increases the testing time, reduces the testing efficiency, and makes the equipment less practical. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing equipment in terms of poor practicality, and to propose a gas tightness testing device and method for the weld seam of stainless steel pipes.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a gas tightness testing device for weld seams of stainless steel pipes, comprising a pipe and a sliding base plate. Two outer frames are provided on the top of the sliding base plate. A pressurizing component and a pressure sensor are respectively fixedly connected through the center of each of the two outer frames. Conductive rubber is rotatably connected to the outer walls of the pressurizing component and the pressure sensor. The ends of the two conductive rubbers are fixedly connected to the inner walls of the corresponding outer frames, and a filling gap is provided between the conductive rubbers and the outer frames. The two filling gaps correspond to the two ends of the pipe. A raised ring is fixedly installed on the outer wall of each of the two conductive rubbers. A sealing ring is fixedly installed on the inner wall of each of the two outer frames, and the sealing ring is located within the filling gap. The sealing ring corresponds to the outer wall of the pipe, and the raised ring corresponds to the inner wall of the pipe. A liquid storage chamber is provided inside each of the two outer frames, and a liquid guide port communicates with the corresponding filling gap. The liquid storage chamber is filled with magnetic fluid. A piston assembly is provided inside each of the two liquid storage chambers. A heating component is provided inside each of the two outer frames.

[0006] Preferably, the heating assembly includes an induction coil fixedly installed within the outer frame, the induction coil being located around the liquid storage chamber.

[0007] Preferably, the piston assembly includes a sealed piston slidably connected within the liquid storage chamber, the sealed piston being fixedly connected to a compression rod, the compression rod passing through the outer frame and slidably connected to the outer frame.

[0008] Preferably, a rotator is provided on each side of the two outer frames that are far apart from each other. The two rotators correspond to two sets of piston assemblies. The end of the rotator near the outer frame is the rotating end, and the rotating end is fixedly connected to the extrusion rod on the corresponding side.

[0009] Preferably, the top of the sliding base plate is slidably connected to two first slides, and the tops of the two first slides are respectively fixedly connected to the bottoms of the two rotators.

[0010] Preferably, the top of the sliding base plate is provided with two mounting plates, and the top of each of the two mounting plates is provided with a fixing device, which is used to fix the pipe.

[0011] Preferably, the top of the sliding base plate is provided with two side sliding grooves, the two side sliding grooves are parallel, the two mounting plates are located between the two side sliding grooves, and the bottom of the two mounting plates are respectively provided with sliding components. The sliding components include two sliding columns fixedly installed on the bottom of the mounting plate. The two sliding columns correspond to the two side sliding grooves respectively and are slidably connected to the side sliding grooves on the corresponding sides.

[0012] Preferably, an application plate is provided between the two mounting plates. The application plate is arc-shaped and is used to apply soap solution to the weld seam of the pipe.

[0013] Preferably, a second slide is slidably connected to the top of the sliding base plate, and the second slide is located between the two mounting plates. A hydraulic rod is fixedly installed on the top of the second slide, and the top of the hydraulic rod is fixedly connected to the bottom of the coating plate.

[0014] A method for testing the gas tightness of weld seams in stainless steel pipes, using the aforementioned gas tightness testing device for weld seams in stainless steel pipes, includes the following steps:

[0015] S1. Prepare by replenishing the soapy water in the coating plate, adding magnetic fluid to the storage chamber, adjusting the position of the mounting plate by sliding the sliding column, and fixing the pipe to the mounting plate with the fixing device.

[0016] S2. Sealing and filling: The sliding first slide table inserts the two ends of the pipe into the corresponding outer frame. The convex ring is in close contact with the inner wall of the pipe, and the sealing ring is in close contact with the outer wall of the pipe. The first slide table drives the extrusion rod to push the sealing piston, squeezing the magnetic fluid in the storage chamber into the filling gap. Then the induction coil is energized, the conductive rubber and the sealing ring are heated and expanded, the magnetic fluid is solidified, and the filling gap is sealed.

[0017] S3. Apply the soap solution. Slide the second slide to align the application plate with the weld seam of the pipe. Start the hydraulic rod to adjust the height of the application plate so that it contacts the weld seam. Start the rotary actuator. The extrusion rod drives the outer frame and the pipe to rotate. The application plate applies soap solution to the weld seam. After the application is completed, stop the rotary actuator. The hydraulic rod drives the application plate away from the pipe surface.

[0018] S4. Test: Connect the pressurization component and pressure sensor to the external equipment, start the pressurization component to fill the pipeline with helium, observe the value of the pressure sensor, and stop filling the pipeline after the pressure in the pipeline is increased to the specified value. Observe whether the pressure value changes and whether there are bubbles generated at the weld to determine the gas sealing of the weld.

[0019] S5. Clean up, disconnect the power supply to the induction coil, the magnetofluid returns to a fluid state, pull the sealing piston with the squeezing rod to draw the magnetofluid in the filling gap back into the storage chamber, and remove the pipe.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] This invention ensures a tight seal at both ends of the pipe by setting a sealing ring and a raised ring, effectively preventing leakage of test gas and improving the accuracy of the test. When the induction coil is energized, the conductive rubber and the sealing ring are heated and expanded simultaneously, which helps the raised ring and the sealing ring to make a tighter contact with the pipe, further improving the sealing performance and helping to improve the accuracy of the test.

[0022] This invention utilizes magnetic fluid to seal and fill gaps. Even with slight changes in pipe diameter or uneven surfaces, the magnetic fluid can tightly adhere to the pipe surface, forming a tight sealing layer. When the induction coil is energized, the magnetic fluid solidifies, forming a magnetic structure that adapts to the shape of the gap. The attraction between particles is enhanced in the magnetic field, gradually forming an orderly arrangement such as chains or patterns, effectively restricting the flow of the carrier fluid and making the magnetic fluid exhibit solid properties. This change increases the sealing effect of the magnetic fluid on the filled gaps, greatly reducing the risk of gas leakage and ensuring the sealing and accuracy of subsequent measurements. In addition, the magnetic fluid's flexibility protects the pipe surface from damage, avoiding scratches or damage caused by hard objects in traditional sealing methods, thus extending the pipe's service life. After the test is completed, the induction coil power is disconnected, and the magnetic fluid returns to a fluid state. The magnetic fluid is then retracted into the storage chamber by a squeezing rod for the next test, thereby improving the utilization rate of the equipment and enhancing its practicality.

[0023] This invention uses a rotating device and a coating plate to rotate the pipe, allowing soap solution to be quickly and thoroughly applied to the weld. The pressurization component is then activated to fill the weld with gas. By observing the changes in the pressure sensor readings and whether bubbles are generated at the weld, a leak can be accurately identified. This testing process is not only efficient but also provides a direct view of the weld's sealing condition, facilitating the timely detection and handling of potential problems. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall isometric structure of a gas tightness testing device and method for weld seams of stainless steel pipes proposed in this invention.

[0025] Figure 2 This is a schematic diagram of the pressurization components and pressure sensor structure of a gas tightness testing device and method for weld seams of stainless steel pipes proposed in this invention.

[0026] Figure 3 This is a schematic diagram of the hydraulic rod and coating plate structure of a gas tightness testing device and method for weld seams of stainless steel pipes proposed in this invention.

[0027] Figure 4 This is a schematic diagram of the extrusion rod and rotator structure of a gas tightness testing device and method for weld seams of stainless steel pipes proposed in this invention.

[0028] Figure 5 This is a schematic diagram of the outer frame and a half-section of the pipe structure of a gas tightness testing device and method for weld seams of stainless steel pipes proposed in this invention.

[0029] Figure 6 for Figure 5 A magnified structural diagram of A in the middle.

[0030] In the diagram: 1 Sliding base plate, 2 Side slide groove, 3 First slide table, 4 Second slide table, 5 Hydraulic rod, 6 Coating plate, 7 Pipe, 8 Sliding column, 9 Mounting plate, 10 Fixer, 11 Rotator, 12 Extrusion rod, 13 Outer frame, 14 Pressurization assembly, 15 Pressure sensor, 16 Conductive rubber, 17 Convex ring, 18 Induction coil, 19 Liquid storage chamber, 20 Sealing piston, 21 Liquid guide port, 22 Filling gap, 23 Sealing ring. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0032] Reference Figures 1 to 6A gas tightness testing device for weld seams of stainless steel pipes includes a sliding base plate 1 and a pipe 7. The top of the sliding base plate 1 has two parallel side sliding grooves 2. Two mounting plates 9 are positioned between the two side sliding grooves 2. Sliding components are respectively provided at the bottom of the two mounting plates 9. Each sliding component includes two sliding columns 8 fixedly installed at the bottom of the mounting plate 9, and the two sliding columns 8 are slidably connected to the corresponding side sliding grooves 2. Fixers 10 are respectively provided at the top of the two mounting plates 9 for fixing the pipe 7. Two first sliding platforms 3 are slidably connected to the top of the sliding base plate 1, distributed on both sides of the two mounting plates 9. Rotators 11 are fixedly installed on the top of each of the two first sliding platforms 3. The ends of the two rotators 11 that are close to each other are rotating ends. A set of extrusion rods 12 are fixedly connected to the rotating ends of the two rotators 11. Outer frames 13 are slidably connected to the ends of the two sets of extrusion rods 12 that are close to each other. The two outer frames 13 correspond to the two ends of the pipe 7. The two fixers 10 are located between the two outer frames 13.

[0033] Conductive rubber 16 is fixedly connected to the center of the inner wall of each of the two outer frames 13, and a filling gap 22 is provided between the conductive rubber 16 and the outer frame 13. The filling gap 22 is annular and its width is greater than the thickness of the pipe 7. A pressurizing component 14 and a pressure sensor 15 are rotatably connected to each of the two outer frames 13, and the pressurizing component 14 and the pressure sensor 15 pass through the corresponding outer frame 13 and the conductive rubber 16, and are rotatably connected to the conductive rubber 16. A convex ring 17 is fixedly installed on the outer wall of each of the two conductive rubbers 16. Sealing rings 23 are fixedly installed on the inner walls of the two outer frames 13, and the sealing rings 23 are located in the corresponding filling gaps 22. The sealing rings 23 correspond to the outer wall of the pipe 7, and the convex rings 17 correspond to the inner wall of the pipe 7. The end of the pipe 7 is inserted into the corresponding filling gap 22. The sealing rings 23 and the conductive rubber 16 deform, so that the sealing rings 23 fit tightly against the outer wall of the pipe 7, and the convex rings 17 fit tightly against the inner wall of the pipe 7, thereby sealing the filling gaps 22. The interiors of the two outer frames 13 are respectively provided with filling components, which include A liquid storage chamber 19 is located within the outer frame 13 and is filled with magnetic fluid. A sealing piston 20 is slidably connected within the liquid storage chamber 19 and is fixedly connected to a corresponding squeezing rod 12. The liquid storage chamber 19 is connected to a corresponding filling gap 22 via a guide port 21. After the filling gap 22 is sealed, sliding the first slide 3 causes the squeezing rod 12 to push the sealing piston 20 to squeeze the magnetic fluid within the liquid storage chamber 19. The magnetic fluid enters the filling gap 22 from the guide port 21. A convex ring 17 intercepts the magnetic fluid from entering the pipe 7, and a sealing ring 23 also intercepts it. The magnetofluid flows to the outside of the device. Induction coils 18 are fixedly installed inside the two outer frames 13, and the induction coils 18 are located on the periphery of the liquid storage chamber 19. The sealing ring 23 and the conductive rubber 16 are made of the same material. When the induction coil 18 is energized, the temperature of the outer frame 13 and the conductive rubber 16 is increased through electromagnetic induction. The magnetofluid in the filling gap 22 begins to solidify under the action of the magnetic field, completely sealing the filling gap 22. The conductive rubber 16 and the sealing ring 23 expand simultaneously due to heat, making the sealing effect of the sealing ring 23 and the convex ring 17 better.

[0034] A second slide plate 4 is slidably connected to the top of the sliding base plate 1. The second slide plate 4 is located between two mounting plates 9. A hydraulic rod 5 is fixedly installed on the top of the second slide plate 4, and an application plate 6 is fixedly installed on the top of the hydraulic rod 5. The application plate 6 is arc-shaped. Sliding the second slide plate 4 aligns the application plate 6 with the weld seam of the pipe 7. The hydraulic rod 5 extends and retracts, adjusting the height of the application plate 6 so that it contacts the weld seam of the pipe 7. The rotor 11 is activated, and the extrusion rod 12 drives the outer frame 13 to rotate, causing the pipe 7 to rotate. The application plate 6 applies soap solution to the weld seam of the pipe 7. After the application is completed, the rotor 11 stops, and the hydraulic rod 5 drives the application plate 6 away. On the surface of pipe 7, pressurization component 14 and pressure sensor 15 are connected to external devices. Pressurization component 14 is activated to fill pipe 7 with helium. The value of pressure sensor 15 is observed. After the pressure in pipe 7 reaches the specified value, the filling stops. The pressure value is observed for a period of time to see if it changes. At the same time, the weld seam is observed to see if there are any bubbles to determine if there is a leak. After the test is completed, the power supply of induction coil 18 is disconnected to allow the magnetic fluid to return to a fluid state. The sealing piston 20 is pulled away from pipe 7 by squeezing rod 12, so that the magnetic fluid in the filling gap 22 returns to the storage chamber 19.

[0035] A method for testing the gas tightness of weld seams in stainless steel pipes, using the aforementioned gas tightness testing device for weld seams in stainless steel pipes, includes the following steps:

[0036] S1. Prepare and replenish the soap water in the coating plate 6, add magnetic fluid to the liquid storage chamber 19, slide the sliding column 8 to adjust the position of the mounting plate 9, and fix the pipe 7 to the mounting plate 9 through the fixing device 10.

[0037] S2. Sealing and filling: The sliding first slide 3 inserts the two ends of the pipe 7 into the corresponding outer frame 13. The convex ring 17 is in close contact with the inner wall of the pipe 7, and the sealing ring 23 is in close contact with the outer wall of the pipe 7. The first slide 3 drives the extrusion rod 12 to push the sealing piston 20, squeezing the magnetic fluid in the liquid storage chamber 19 into the filling gap 22. Then, the induction coil 18 is energized, the temperature of the outer frame 13 and the conductive rubber 16 rises, and the magnetic fluid solidifies under the action of the magnetic field, sealing the filling gap 22.

[0038] S3. Apply the soap solution. Slide the second slide table 4 to align the application plate 6 with the weld of the pipe 7. Start the hydraulic rod 5 to adjust the height of the application plate 6 so that it contacts the weld. Start the rotator 11. The extrusion rod 12 drives the outer frame 13 and the pipe 7 to rotate. The application plate 6 applies soap solution to the weld. After the application is completed, stop the rotator 11. The hydraulic rod 5 drives the application plate 6 away from the surface of the pipe 7.

[0039] S4. Test: Connect the pressurization component 14 and pressure sensor 15 to external equipment, start the pressurization component 14 to fill the pipe 7 with helium, observe the value of the pressure sensor 15, and stop filling the pipe 7 after the pressure is increased to the specified value. Observe whether the pressure value changes and whether there are bubbles generated at the weld. Judge the gas sealing of the weld based on the pressure change and the bubble situation.

[0040] S5. Clean up, disconnect the power supply to the induction coil 18, the magnetic fluid returns to a fluid state, pull the sealing piston 20 by the squeezing rod 12 to draw the magnetic fluid in the filling gap 22 back into the storage chamber 19, and remove the pipe 7.

[0041] In this invention, the pipe 7 is fixed by the fixture 10 on the mounting plate 9, and then the weld of the pipe 7 is aligned and contacted with the coating plate 6 by the sliding of the first slide table 3 and the second slide table 4 on the sliding base plate 1 and the sliding of the sliding column 8 on the side sliding groove 2. The coating plate 6 is pre-filled with soapy water to ensure that the soapy water can be applied to the weld later. Magnetic fluid is added to the liquid storage chamber 19 inside the outer frame 13 in advance, and both ends of the pipe 7 are inserted into the outer frame 13 for sealing.

[0042] After the pipe 7 is inserted into the outer frame 13, the pipe 7 is stuck in the filling gap 22 between the conductive rubber 16 and the outer frame 13. The front end of the conductive rubber 16 extends into the pipe 7 and has a raised ring 17 at the front end. Due to the deformation of the conductive rubber 16, the raised ring 17 is tightly attached to the inner wall of the pipe 7. A sealing ring 23 is provided at the contact point between the outer frame 13 and the outer wall of the pipe 7. The sealing ring 23 deforms and is tightly attached to the outer wall of the pipe 7, so that both ends of the filling gap 22 are sealed.

[0043] The first slide 3 is moved towards the center of the sliding base plate 1. The sealing piston 20 at the front end of the extrusion rod 12 guides the magnetic fluid in the storage chamber 19 through the liquid guide port 21 into the filling gap 22. Simultaneously, the induction coil 18 is energized, increasing the temperature of the outer frame 13 and the conductive rubber 16. Under the influence of the magnetic field, the magnetic fluid in the filling gap 22 begins to solidify, completely sealing the gap and ensuring the sealing performance of subsequent measurements. The advantages of this design are:

[0044] First, the carrier fluid of the magnetic fluid is water or oil, which forms a colloid in the filling gap 22, which can itself play a liquid sealing role and improve the sealing performance. Under the action of the magnetic field of the induction coil 18, it is magnetized into a solid. The magnetic structure formed can fill the filling gap 22. The magnetic fluid itself has a certain fluidity and can adapt to the shape of the gap. In the magnetized state, the mutual attraction between particles will be enhanced by the magnetic field, gradually forming ordered structures such as chains or columns. These structures will restrict the flow of the carrier fluid, making the magnetic fluid exhibit solid properties. The changes in its internal structure can increase its sealing effect on the filling gap 22. The pipe diameter of the pipe 7 may have slight size changes or uneven surface. The magnetic fluid can better fit the surface of the pipe 7 according to these conditions to form a tighter seal, reduce the risk of gas or liquid leakage, and thus improve the accuracy of measurement.

[0045] Second: The temperature of the conductive rubber 16 rises rapidly, and the thermal expansion and contraction effect of the rubber is more obvious. Therefore, the conductive rubber 16 and the sealing ring 23 undergo thermal expansion, which makes the convex ring 17 and the sealing ring 23 contact the pipe 7 more tightly, thus enhancing the sealing effect.

[0046] Third: The magnetized magnetic fluid inside the gap 22 is in a state similar to a "soft solid", which can protect the surface of the pipe 7 from damage.

[0047] After sealing, start the rotator 11 to fully coat the weld of pipe 7 with soap solution. After coating, start the hydraulic rod 5, and the coating plate 6 will leave the surface of pipe 7. Then start the pressurization component 14 to fill the inside of pipe 7 with helium. Observe the value on the pressure sensor 15. After the pressure inside pipe 7 is increased to the specified value, stop the inflation. Observe whether the pressure value changes over a period of time. At the same time, observe whether bubbles are generated at the weld to determine whether there is a leak.

[0048] After the test is completed, disconnect the power supply to the induction coil 18 to allow the magnetic fluid to return to a fluid state. Use the squeezing rod 12 to pull the sealing piston 20 back to allow the magnetic fluid to return to the reservoir 19. Remove the pipe 7 to complete the test.

[0049] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A gas tightness testing device for weld seams of stainless steel pipes, comprising a pipe (7), characterized in that, It also includes a sliding base plate (1), the top of which is provided with two outer frames (13). The centers of the two outer frames (13) are respectively rotatably connected to a pressurizing component (14) and a pressure sensor (15). The outer walls of the pressurizing component (14) and the pressure sensor (15) are respectively rotatably connected to conductive rubber (16). The ends of the two conductive rubbers (16) are respectively fixedly connected to the inner walls of the corresponding outer frames (13), and a filling gap (22) is provided between the conductive rubbers (16) and the outer frames (13). The two filling gaps (22) correspond to the two ends of the pipe (7), and the outer walls of the two conductive rubbers (16) are respectively fixedly connected to the inner walls of the pipe (7). A convex ring (17) is fixedly installed on each of the two outer frames (13), and a sealing ring (23) is fixedly installed on the inner wall of each of the two outer frames (13). The sealing ring (23) is located in the filling gap (22). The sealing ring (23) corresponds to the outer wall of the pipe (7), and the convex ring (17) corresponds to the inner wall of the pipe (7). A liquid storage chamber (19) is provided inside each of the two outer frames (13), and a liquid guide port (21) is connected to the corresponding filling gap (22). The liquid storage chamber (19) is filled with magnetic fluid. A piston assembly is provided inside each of the two liquid storage chambers (19), and a heating assembly is provided inside each of the two outer frames (13). The heating assembly includes an induction coil (18) fixedly installed inside the outer frame (13), and the induction coil (18) is located around the liquid storage chamber (19); The piston assembly includes a sealed piston (20) slidably connected in the liquid storage chamber (19), and the sealed piston (20) is fixedly connected to a squeezing rod (12), which passes through the outer frame (13) and is slidably connected to the outer frame (13); The top of the sliding base plate (1) is provided with two mounting plates (9), and the top of the two mounting plates (9) is provided with a fixing device (10), which is used to fix the pipe (7); a coating plate (6) is provided between the two mounting plates (9), the coating plate (6) is arc-shaped, and the coating plate (6) is used to apply soap solution to the weld of the pipe (7); When the induction coil (18) is energized, the temperature of the outer frame (13) and the conductive rubber (16) is increased through electromagnetic induction. The magnetic fluid in the filling gap (22) begins to solidify under the action of the magnetic field, completely sealing the filling gap (22). The conductive rubber (16) and the sealing ring (23) expand simultaneously due to heat, making the sealing ring (23) and the convex ring (17) have a better sealing effect. After the test is completed, the power supply of the induction coil (18) is disconnected, allowing the magnetic fluid to return to a fluid state. The sealing piston (20) is pulled away from the pipe (7) by the squeezing rod (12), so that the magnetic fluid in the filling gap (22) returns to the storage chamber (19).

2. The gas tightness testing device for weld seams of stainless steel pipes according to claim 1, characterized in that, Rotators (11) are respectively provided on the side of the two outer frames (13) that are far apart from each other. The two rotors (11) correspond to the two sets of piston assemblies respectively. The end of the rotor (11) near the outer frame (13) is the rotating end, and the rotating end is fixedly connected to the extrusion rod (12) on the corresponding side.

3. The gas tightness testing device for the weld seam of a stainless steel pipe according to claim 2, characterized in that, The top of the sliding base plate (1) is slidably connected to two first slides (3), and the tops of the two first slides (3) are respectively fixedly connected to the bottoms of the two rotators (11).

4. The gas tightness testing device for weld seams of stainless steel pipes according to claim 3, characterized in that, The top of the sliding base plate (1) is provided with two side sliding grooves (2), the two side sliding grooves (2) are parallel, the two mounting plates (9) are located between the two side sliding grooves (2), and the bottom of the two mounting plates (9) are respectively provided with sliding components. The sliding components include two sliding columns (8) fixedly installed at the bottom of the mounting plate (9). The two sliding columns (8) correspond to the two side sliding grooves (2) respectively, and are slidably connected to the side sliding grooves (2) on the corresponding side.

5. The gas tightness testing device for weld seams of stainless steel pipes according to claim 4, characterized in that, The top of the sliding base plate (1) is slidably connected to a second slide (4), and the second slide (4) is located between two mounting plates (9). A hydraulic rod (5) is fixedly installed on the top of the second slide (4), and the top of the hydraulic rod (5) is fixedly connected to the bottom of the coating plate (6).

6. A method for testing the gas tightness of weld seams in stainless steel pipes, characterized in that, The gas tightness testing device for weld seams of stainless steel pipes according to claim 5 includes the following steps: S1. Prepare, replenish the soap water in the coating plate (6), add magnetic fluid into the storage chamber (19), adjust the position of the mounting plate (9) by sliding the sliding column (8), and fix the pipe (7) on the mounting plate (9) by the fixing device (10); S2, sealing and filling: the first slide (3) slides to insert the two ends of the pipe (7) into the corresponding outer frame (13) respectively. The convex ring (17) is in close contact with the inner wall of the pipe (7), and the sealing ring (23) is in close contact with the outer wall of the pipe (7). The first slide (3) drives the extrusion rod (12) to push the sealing piston (20) to squeeze the magnetic fluid in the liquid storage chamber (19) into the filling gap (22). Then the induction coil (18) is energized, the conductive rubber (16) and the sealing ring (23) are heated and expanded, the magnetic fluid is solidified, and the filling gap (22) is sealed. S3. Apply the soap solution. Slide the second slide (4) to align the application plate (6) with the weld of the pipe (7). Start the hydraulic rod (5) to adjust the height of the application plate (6) so that it contacts the weld. Start the rotator (11). The extrusion rod (12) drives the outer frame (13) and the pipe (7) to rotate. The application plate (6) applies soap solution to the weld. After the application is completed, stop the rotator (11). The hydraulic rod (5) drives the application plate (6) away from the surface of the pipe (7). S4. Test: Connect the pressurizing component (14) and pressure sensor (15) to external equipment, start the pressurizing component (14) to fill the pipe (7) with helium, observe the value of the pressure sensor (15), stop filling the pipe (7) after the pressure is increased to the specified value, observe whether the pressure value changes and whether there are bubbles generated at the weld, and judge the gas sealing of the weld. S5. Clean up, disconnect the power supply of the induction coil (18), the magnetic fluid returns to a fluid state, pull the sealing piston (20) by squeezing rod (12) to draw the magnetic fluid in the filling gap (22) back into the storage chamber (19), and remove the pipe (7).

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