Device and method for testing gas tightness at weld joint of stainless steel pipe

Abstract

The invention relates to the technical field of gas tightness testing, in particular to a device and a method for testing gas tightness at a weld joint of a stainless steel pipe, the testing device comprises a sliding bottom plate, two outer frames are arranged at the top of the sliding bottom plate, and a pressurizing assembly and a pressure sensor are fixedly connected to the circle centers of the two outer frames in a penetrating manner respectively; the outer walls of the pressurizing assembly and the pressure sensor are rotatably connected with conductive rubber respectively, the outer walls of the two conductive rubber are fixedly provided with convex rings respectively, the inner walls of the two outer frames are fixedly provided with sealing rings respectively, the two outer frames are internally provided with liquid storage cavities respectively, and the testing method comprises the steps of preparation, sealing, filling and the like. The filling gap is sealed by the magnetic fluid, even if the pipe diameter of the pipeline changes slightly or the surface of the pipeline is uneven, the magnetic fluid can be tightly attached to the surface of the pipeline to form a tight sealing layer, the magnetic fluid can be solidified to adapt to the shape of the gap, the plugging effect on the filling gap is improved, and the testing accuracy is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of gas tightness testing, and in particular to a device and method for testing the gas tightness of a weld of a stainless steel pipe. Background Art

[0002] The gas tightness test of the weld of stainless steel pipe is to ensure that the sealing of the welding part meets the design requirements, prevent gas leakage, and ensure the safe, reliable and efficient operation of the pipeline system. Through the gas tightness test, defects that may occur during the welding process, such as pores and slag inclusions, can be found, which helps to improve the welding quality and avoid maintenance and repair work caused by sealing problems in the later stage.

[0003] At present, traditional testing devices seal both ends of the pipeline during testing. The pipe diameter is prone to slight changes or uneven surfaces. Traditional sealing methods cannot fit the pipe surface tightly, resulting in poor sealing. Even if there is a slight leak in the weld, it is easy to go undetected due to poor sealing, thus affecting the accuracy of the test. It is difficult for testers to determine whether there is a leak in the weld, which increases the test time and reduces the test efficiency, making the equipment less practical. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcoming of poor practicability of the equipment in the prior art, and to propose a gas tightness testing device and method at the weld of a stainless steel pipe.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a gas tightness test device at the weld of a stainless steel pipe, comprising a pipeline and a sliding bottom plate, wherein two outer frames are arranged on the top of the sliding bottom plate, and the centers of the two outer frames are respectively penetrated and fixedly connected with a pressurizing component and a pressure sensor, and the outer walls of the pressurizing component and the pressure sensor are respectively rotatably connected with conductive rubber, and the ends of the two conductive rubbers are respectively fixedly connected with the inner walls of the outer frames on the corresponding sides, and a filling gap is arranged between the conductive rubber and the outer frame, and the two filling gaps correspond to the two ends of the pipeline respectively, and the outer walls of the two conductive rubbers are respectively fixedly installed with convex rings, and the inner walls of the two outer frames are respectively fixedly installed with sealing rings, and the sealing rings are located in the filling gaps, and the sealing rings correspond to the outer walls of the pipeline, and the convex rings correspond to the inner walls of the pipeline, and the two outer frames are respectively provided with liquid storage cavities, and the liquid storage cavities are connected with the corresponding filling gaps by a liquid guide port, and the liquid storage cavity is filled with magnetic fluid, and the two liquid storage cavities are respectively provided with piston assemblies, and the two outer frames are respectively provided with heating assemblies.

[0006] Preferably, the heating assembly comprises an induction coil fixedly mounted in the outer frame, and the induction coil is located at the periphery of the liquid storage cavity.

[0007] Preferably, the piston assembly comprises a sealing piston slidably connected in the liquid storage chamber, the sealing piston is fixedly connected with an extrusion rod, the extrusion rod passes through the outer frame and is slidably connected to the outer frame.

[0008] Preferably, a rotator is provided on one side of the two outer frames away from each other, and the two rotators correspond to two groups of piston assemblies respectively. The end of the rotator close to 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 bottom plate is slidably connected to two first slides, and the tops of the two first slides are fixedly connected to the bottoms of the two rotators respectively.

[0010] Preferably, two mounting plates are arranged on the top of the sliding bottom plate, and fixers are respectively arranged on the tops of the two mounting plates, and the fixers are used to fix the pipeline.

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

[0012] Preferably, an smear plate is provided between the two mounting plates, the smear plate is arc-shaped, and the smear plate is used to smear soap liquid on the weld of the pipeline.

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

[0014] A method for testing the gas tightness of a weld of a stainless steel pipe, using the above-mentioned device for testing the gas tightness of a weld of a stainless steel pipe, comprises the following steps: S1. Preparation: replenish soapy water in the smear plate, add magnetic fluid into the liquid storage chamber, slide the slide column to adjust the position of the mounting plate, and fix the pipe on the mounting plate through the fixture; S2, sealing and filling, sliding the first slide to insert the two ends of the pipe into the outer frame on the corresponding side, 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 drives the extrusion rod to push the sealing piston to squeeze the magnetic fluid in the liquid storage chamber into the filling gap. Then the induction coil is energized, the conductive rubber and the sealing ring expand due to heat, the magnetic fluid solidifies, and the filling gap is closed; S3, smearing, slide the second slide to align the smear plate with the weld of the pipeline, start the hydraulic rod, adjust the height of the smear plate to make it contact with the weld, start the rotator, the extrusion rod drives the outer frame and the pipeline to rotate, and the smear plate smears the soap liquid on the weld. After the smearing is completed, stop the rotator, and the hydraulic rod drives the smear plate to leave the pipeline surface; S4, test, pressurizing component and pressure sensor external equipment, start the pressurizing component to fill the pipeline with helium, observe the value of the pressure sensor, stop the inflation after the pressure in the pipeline is increased to the specified value, observe whether the pressure value changes and whether bubbles are generated at the weld, and judge the gas tightness of the weld; S5. Clean up, disconnect the power supply of the induction coil, and restore the magnetic fluid to a fluid state. Pull the sealing piston through the extrusion rod to draw the magnetic fluid in the filling gap back into the liquid storage chamber, and remove the pipeline.

[0015] Compared with the prior art, the advantages of the present invention are: The present invention ensures tight sealing at both ends of the pipeline by arranging sealing rings and convex rings, effectively prevents leakage of test gas, and improves the accuracy of the test; when the induction coil is energized, the conductive rubber and the sealing ring expand due to heat at the same time, which helps the convex ring and the sealing ring to contact the pipeline more closely, further improves the sealing performance, and helps to improve the accuracy of the detection.

[0016] The present invention utilizes magnetic fluid to seal and fill the gap. Even if the diameter of the pipeline changes slightly or the surface is uneven, the magnetic fluid can closely fit the surface of the pipeline to form a tight sealing layer. When the induction coil is energized, the magnetic fluid solidifies to form a magnetic structure that can adapt to the shape of the gap. The attraction between the particles is enhanced in the magnetic field, gradually forming an orderly arrangement such as a chain or a sample, effectively restricting the flow of the carrier liquid, and making the magnetic fluid exhibit the properties of a solid. This change increases the sealing effect of the magnetic fluid on the filling gap, greatly reduces the risk of gas leakage, and ensures the sealing and accuracy of subsequent measurements. In addition, the magnetic fluid also protects the pipeline surface from damage with its flexible characteristics, avoids scratches or damage to the pipeline surface caused by squeezing of hard objects in traditional sealing methods, and extends the service life of the pipeline. After the test is completed, the power supply of the induction coil is disconnected, the magnetic fluid returns to a fluid state, and the magnetic fluid is recovered into the liquid storage chamber through the extrusion rod for the next test, thereby improving the utilization rate of the equipment and enhancing the practicality of the equipment.

[0017] The present invention arranges devices such as a rotator and a smear plate, and the pipeline rotates so that the weld can be quickly and fully smeared with soap liquid. The pressurizing component is started to fill with gas, and the value change of the pressure sensor is observed. At the same time, it is observed whether bubbles are generated at the weld, so as to accurately determine whether there is a leak point. This testing process is not only efficient, but also can intuitively reflect the sealing condition of the weld, making it easy to timely discover and deal with potential problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention provides an overall axonometric structural schematic diagram of a device and method for testing the gas tightness at a weld of a stainless steel pipe.

[0019] Figure 2 The present invention provides a schematic diagram of a pressurizing component and a pressure sensor structure of a device and method for testing the gas tightness at a weld of a stainless steel pipe.

[0020] Figure 3 This is a schematic diagram of the hydraulic rod and smear plate structure of a device and method for testing gas tightness at a weld of a stainless steel pipe proposed in the present invention.

[0021] Figure 4 The present invention provides a schematic diagram of the structure of an extrusion rod and a rotator of a device and method for testing the gas tightness at a weld of a stainless steel pipe.

[0022] Figure 5 This is a schematic diagram of the outer frame and pipe half-section structure of a device and method for testing gas tightness at a weld of a stainless steel pipe proposed in the present invention.

[0023] Figure 6 for Figure 5 Schematic diagram of the enlarged structure of A.

[0024] In the figure: 1 sliding base plate, 2 side slide groove, 3 first slide, 4 second slide, 5 hydraulic rod, 6 smear plate, 7 pipeline, 8 sliding column, 9 mounting plate, 10 fixer, 11 rotator, 12 extrusion rod, 13 outer frame, 14 pressurizing component, 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 DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0026] Reference Figures 1 to 6, a gas tightness testing device for the weld of a stainless steel pipe, comprising a sliding base plate 1 and a pipeline 7, two side slide grooves 2 are arranged on the top of the sliding base plate 1, the two side slide grooves 2 are parallel, two mounting plates 9 are arranged between the two side slide grooves 2, and sliding components are respectively arranged at the bottom of the two mounting plates 9, the sliding components include two sliding columns 8 fixedly installed at the bottom of the mounting plate 9, the two sliding columns 8 are respectively slidably connected to the side slide grooves 2 on the corresponding sides, and the tops of the two mounting plates 9 are respectively provided with fixers 10, and the fixers 10 are used to fix the pipeline 7, the top of the sliding base plate 1 is slidably connected with two first slides 3, the two first slides 3 are distributed on both sides of the two mounting plates 9, and the tops of the two first slides 3 are respectively fixedly installed with rotators 11, the ends of the two rotators 11 close to each other are the rotating ends, and the rotating ends of the two rotators 11 are respectively fixedly connected with a group of extrusion rods 12, and the ends of the two groups of extrusion rods 12 close to each other are respectively slidably connected with outer frames 13, the two outer frames 13 correspond to the two ends of the pipeline 7, and the two fixers 10 are located between the two outer frames 13.

[0027] The inner centers of the two outer frames 13 are respectively fixedly connected with conductive rubber 16, and a filling gap 22 is provided between the conductive rubber 16 and the outer frame 13. The filling gap 22 is annular, and the width of the filling gap 22 is greater than the thickness of the pipe 7. The two outer frames 13 are respectively rotatably connected with a pressurizing component 14 and a pressure sensor 15, and the pressurizing component 14 and the pressure sensor 15 respectively penetrate the corresponding outer frame 13 and the conductive rubber 16, and are rotatably connected with the conductive rubber 16. The outer walls of the two conductive rubbers 16 are respectively fixedly installed with convex rings 17. The inner walls of the two outer frames 13 are respectively fixed with sealing rings 23, 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 filling gap 22 on the corresponding side. The sealing rings 23 and the conductive rubber 16 are deformed, so that the sealing rings 23 are closely attached to the outer wall of the pipe 7, and the convex rings 17 are closely attached to the inner wall of the pipe 7, so that the filling gap 22 is sealed. The interiors of the two outer frames 13 are respectively provided with filling components, and the filling components include A liquid storage chamber 19 is provided in the outer frame 13, and the liquid storage chamber 19 is filled with magnetic fluid. A sealing piston 20 is slidably connected in the liquid storage chamber 19, and the sealing piston 20 is fixedly connected to the extrusion rod 12 on the corresponding side. The liquid storage chamber 19 is connected to the corresponding filling gap 22 through a liquid guide port 21. After the filling gap 22 is sealed, the first slide 3 is slid so that the extrusion rod 12 pushes the sealing piston 20 to squeeze the magnetic fluid in the liquid storage chamber 19, and the magnetic fluid enters the filling gap 22 from the liquid guide port 21. The convex ring 17 intercepts the magnetic fluid from entering the pipeline 7, and the sealing ring 23 intercepts The magnetic fluid flows to the outside of the device, and the 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 the electromagnetic induction effect. The magnetic fluid in the filling gap 22 begins to solidify under the action of the magnetic field, and the filling gap 22 is completely closed. The conductive rubber 16 and the sealing ring 23 expand due to the heat at the same time, so that the sealing effect of the sealing ring 23 and the convex ring 17 is better.

[0028] The top of the sliding bottom plate 1 is slidably connected with 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 a smear plate 6 is fixedly installed on the top of the hydraulic rod 5. The smear plate 6 is arc-shaped. The second slide 4 is slid so that the smear plate 6 is aligned with the weld of the pipe 7. The hydraulic rod 5 is extended and retracted to adjust the height of the smear plate 6 so that it contacts the weld of the pipe 7. The rotator 11 is started, and the extrusion rod 12 drives the outer frame 13 to rotate, so that the pipe 7 rotates. The smear plate 6 smears the soap liquid on the weld of the pipe 7. After the smearing is completed, the rotator 11 stops, and the hydraulic rod 5 drives the smear plate 6 to leave The surface of the pipeline 7 is then inspected by the pressurizing component 14 and the pressure sensor 15, respectively. The pressurizing component 14 is started to fill the pipeline 7 with helium, and the value of the pressure sensor 15 is observed. After the pressure in the pipeline 7 reaches the specified value, the inflation is stopped. During a subsequent period of time, it is observed whether the pressure value changes. At the same time, it is observed whether bubbles are generated at the weld to determine whether there is a leak. After the test is completed, the power supply of the induction coil 18 is disconnected to restore the magnetic fluid to a fluid state. The sealing piston 20 is pulled away from the pipeline 7 by the extrusion rod 12, so that the magnetic fluid in the filling gap 22 returns to the liquid storage chamber 19.

[0029] A method for testing the gas tightness of a weld of a stainless steel pipe, using the above-mentioned device for testing the gas tightness of a weld of a stainless steel pipe, comprises the following steps: S1, preparation, replenishing the soapy water in the smear plate 6, adding magnetic fluid into the liquid storage chamber 19, sliding the sliding column 8 to adjust the position of the mounting plate 9, and fixing the pipe 7 on the mounting plate 9 through the fixture 10; S2, sealing and filling, sliding the first slide 3 to insert the two ends of the pipe 7 into the outer frame 13 on the corresponding side 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, and squeezes 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 increases, and the magnetic fluid solidifies under the action of the magnetic field, and the filling gap 22 is closed; S3, smearing, slide the second slide 4, align the smear plate 6 with the weld of the pipe 7, start the hydraulic rod 5, adjust the height of the smear plate 6 to make it contact with the weld, start the rotator 11, the extrusion rod 12 drives the outer frame 13 and the pipe 7 to rotate, and the smear plate 6 smears the soap liquid on the weld. After the smearing is completed, stop the rotator 11, and the hydraulic rod 5 drives the smear plate 6 to leave the surface of the pipe 7; S4, test, pressurizing component 14 and pressure sensor 15 are connected to external equipment, pressurizing component 14 is started to fill helium into pipe 7, the value of pressure sensor 15 is observed, and the inflation is stopped after the pressure in pipe 7 is increased to a specified value, and whether the pressure value changes and whether bubbles are generated at the weld is observed, and the gas tightness at the weld is determined according to the pressure change and bubble situation; S5, cleaning, disconnecting the power supply of the induction coil 18, the magnetic fluid returns to a fluid state, and the sealing piston 20 is pulled by the extrusion rod 12 to draw the magnetic fluid in the filling gap 22 back into the liquid storage chamber 19, and the pipeline 7 is removed.

[0030] In the present 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 smear plate 6 by the sliding of the first slide 3 and the second slide 4 on the sliding base plate 1, and the sliding column 8 on the side slide groove 2. The smear plate 6 is pre-filled with soapy water to ensure that soapy water can be applied to the weld later, and magnetic fluid is added to the liquid storage chamber 19 in the outer frame 13 in advance, and the two ends of the pipe 7 are inserted into the outer frame 13 for sealing.

[0031] 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 a circle of convex rings 17 are provided at the front end. Relying on the deformation of the conductive rubber 16, the convex rings 17 are tightly fitted to the inner wall of the pipe 7. A sealing ring 23 is provided at the place where the outer frame 13 contacts the outer wall of the pipe 7. The sealing ring 23 is deformed and tightly fitted to the outer wall of the pipe 7, so that both ends of the filling gap 22 are closed.

[0032] Start the first slide 3 to move toward the middle of the sliding bottom plate 1, use the sealing piston 20 at the front end of the extrusion rod 12 to guide the magnetic fluid in the liquid storage chamber 19 into the filling gap 22 through the liquid guide port 21, and at the same time energize the induction coil 18, the temperature of the outer frame 13 and the conductive rubber 16 increases, and the magnetic fluid in the filling gap 22 begins to solidify under the action of the magnetic field, completely sealing the filling gap 22 to ensure the sealing of subsequent measurements. The advantages of this design are: First, the carrier liquid of the magnetic fluid is water or oil, so that a colloid is formed in the filling gap 22, which can itself play a liquid seal effect and improve the sealing performance. It is magnetized into a solid under the magnetic field of the induction coil 18, and 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 the particles will be enhanced due to the magnetic field, and gradually form an ordered structure such as a chain or a column. These structures will limit the flow of the carrier liquid, so that the magnetic fluid exhibits the properties of a solid. The change in its internal structure can increase its sealing effect on the filling gap 22. The diameter of the pipe 7 will have a slight size change or an uneven surface. The magnetic fluid can better fit the surface of the pipe 7 according to these conditions, forming a tighter seal, reducing the risk of gas or liquid leakage, thereby improving the accuracy of the measurement; Second, the temperature of the conductive rubber 16 rises rapidly, and the thermal expansion and contraction effect of the rubber is more obvious, so the conductive rubber 16 and the sealing ring 23 expand thermally, so that the convex ring 17 and the sealing ring 23 are in closer contact with the pipe 7, thereby enhancing the sealing effect; Third: the magnetized magnetic fluid in the filling gap 22 is in a state similar to a "soft solid", which can protect the surface of the pipeline 7 from being damaged.

[0033] After sealing, start the rotator 11 to allow the weld of the pipe 7 to be fully coated with soap liquid. After coating, start the hydraulic rod 5, the coating plate 6 leaves the surface of the pipe 7, and then start the pressurizing component 14 to fill helium into the interior of the pipe 7. Observe the value on the pressure sensor 15, and stop the inflation after the pressure in the pipe 7 is increased to a specified value. Observe whether the pressure value changes over a period of time, and observe whether bubbles are generated at the weld to determine whether there is a leak.

[0034] After the test is completed, the power supply of the induction coil 18 is disconnected to allow the magnetic fluid to return to a fluid state, and the sealing piston 20 is pulled back by the extrusion rod 12 to allow the magnetic fluid to return to the liquid storage chamber 19, and the pipeline 7 is removed to complete the test.

[0035] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A gas tightness testing device for a weld of a stainless steel pipe, comprising a pipe (7), characterized in that: The invention also comprises a sliding bottom plate (1), wherein two outer frames (13) are arranged on the top of the sliding bottom plate (1), wherein the centers of the two outer frames (13) respectively penetrate a pressurizing component (14) and a pressure sensor (15) which are rotatably connected, wherein the outer walls of the pressurizing component (14) and the pressure sensor (15) are respectively rotatably connected with conductive rubber (16), wherein the ends of the two conductive rubbers (16) are respectively fixedly connected to the inner walls of the outer frames (13) on the corresponding sides, and a filling gap (22) is arranged between the conductive rubber (16) and the outer frame (13), wherein the two filling gaps (22) respectively correspond to the two ends of the pipe (7), and the outer walls of the two conductive rubbers (16) are respectively connected to the inner walls of the outer frames (13) on the corresponding sides. A convex ring (17) is fixedly mounted on each of the two outer frames (13); a sealing ring (23) is fixedly mounted on the inner walls 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 pipeline (7); the convex ring (17) corresponds to the inner wall of the pipeline (7); a liquid storage cavity (19) is provided inside each of the two outer frames (13); the liquid storage cavity (19) is connected to the corresponding filling gap (22) via a liquid guide port (21); the liquid storage cavity (19) is filled with magnetic fluid; a piston assembly is provided inside each of the two liquid storage cavities (19); and a heating assembly is provided inside each of the two outer frames (13).

2. A gas tightness testing device for a weld of a stainless steel pipe according to claim 1, characterized in that: The heating component comprises an induction coil (18) fixedly mounted in the outer frame (13); the induction coil (18) is located outside the liquid storage cavity (19).

3. A gas tightness testing device for a weld of a stainless steel pipe according to claim 2, characterized in that: The piston assembly comprises a sealing piston (20) slidably connected in the liquid storage chamber (19); the sealing piston (20) is fixedly connected to an extrusion rod (12); the extrusion rod (12) penetrates the outer frame (13) and is slidably connected to the outer frame (13).

4. A gas tightness testing device for a weld of a stainless steel pipe according to claim 3, characterized in that: Rotators (11) are respectively provided on the sides of the two outer frames (13) that are away from each other. The two rotators (11) correspond to the two groups of piston assemblies respectively. The end of the rotator (11) close to the outer frame (13) is a rotating end, and the rotating end is fixedly connected to the extrusion rod (12) on the corresponding side.

5. A gas tightness testing device for a weld of a stainless steel pipe according to claim 4, characterized in that: The top of the sliding bottom plate (1) is slidably connected to two first slides (3), and the tops of the two first slides (3) are fixedly connected to the bottoms of the two rotators (11) respectively.

6. A gas tightness testing device for a weld of a stainless steel pipe according to claim 5, characterized in that: Two mounting plates (9) are arranged on the top of the sliding bottom plate (1), and fixers (10) are respectively arranged on the top of the two mounting plates (9), and the fixers (10) are used to fix the pipeline (7).

7. A gas tightness testing device for a weld of a stainless steel pipe according to claim 6, 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 bottoms of the two mounting plates (9) are respectively provided with sliding components, the sliding components comprising two sliding columns (8) fixedly mounted on the bottoms of the mounting plates (9), the two sliding columns (8) respectively corresponding to the two side sliding grooves (2), and slidably connected to the side sliding grooves (2) on the corresponding sides.

8. A gas tightness testing device for a weld of a stainless steel pipe according to claim 7, characterized in that: An smear plate (6) is provided between the two mounting plates (9); the smear plate (6) is arc-shaped and is used to smear soap liquid on the weld of the pipeline (7).

9. A gas tightness testing device for a weld of a stainless steel pipe according to claim 8, characterized in that: The top of the sliding bottom 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 mounted on the top of the second slide (4), and the top of the hydraulic rod (5) is fixedly connected to the bottom of the smear plate (6).

10. A method for testing the gas tightness of a weld of a stainless steel pipe, characterized in that: The gas tightness testing device for the weld of a stainless steel pipe according to claim 9 comprises the following steps: S1, preparation, replenishing soapy water in the smear plate (6), adding magnetic fluid into the liquid storage chamber (19), sliding the sliding column (8) to adjust the position of the mounting plate (9), and fixing the pipe (7) on the mounting plate (9) through the fixing device (10); S2, sealing and filling, sliding the first slide (3) to insert the two ends of the pipe (7) into the outer frame (13) on the corresponding side, 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), so that the magnetic fluid in the liquid storage chamber (19) is squeezed into the filling gap (22), and 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 closed; S3, applying, sliding the second slide (4) to align the application plate (6) with the weld of the pipe (7), starting the hydraulic rod (5), adjusting the height of the application plate (6) so that it contacts the weld, starting the rotator (11), the extrusion rod (12) drives the outer frame (13) and the pipe (7) to rotate, and the application plate (6) applies the soap liquid to the weld. After the application is completed, the rotator 11 is stopped, and the hydraulic rod (5) drives the application plate (6) to leave the surface of the pipe (7); S4, testing, connecting the pressurizing component (14) and the pressure sensor (15) to external equipment, starting the pressurizing component (14) to fill the pipe (7) with helium, observing the value of the pressure sensor (15), and stopping the filling after the pressure in the pipe (7) is increased to a specified value, observing whether the pressure value changes and whether bubbles are generated at the weld, and judging the gas tightness of the weld; S5, cleaning, disconnecting the power supply of the induction coil (18), the magnetic fluid returns to a fluid state, and the sealing piston (20) is pulled by the extrusion rod (12) to draw the magnetic fluid in the filling gap (22) back into the liquid storage chamber (19), and remove the pipe (7).

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