Welding alignment tool and welding method for outlet check valve of reactor core water replenishing tank

Abstract

The invention relates to the field of nuclear power reactor core water replenishing tank outlet check valve welding, in particular to a welding alignment tool for a reactor core water replenishing tank outlet check valve and a welding method. The tool comprises a rack, two pipeline fixing frames and a valve body supporting and adjusting frame, the rack provides a fixing foundation for other parts, the valve body supporting and adjusting frame is arranged in the center of the rack, and the two pipeline fixing frames are arranged at the two ends of the rack; the valve body supporting and adjusting frame is used for supporting and adjusting the horizontal position and the vertical height of a check valve body, and the pipeline fixing frame is used for supporting and fixing a check valve butt joint pipeline. The valve body supporting and adjusting frame is used for supporting and adjusting the horizontal position and the vertical height of the valve, the worm gear lifting machine and the guide column are installed in the support to achieve adjustment and locking of any height, the horizontal position adjusting mechanism freely slides through the linear guide rail and the sliding block, and then rapid centering of the CMT outlet check valve and the butt joint pipeline welding seam lip edge is achieved. The labor intensity of personnel can be reduced and the working efficiency is effectively improved.

Description

Technical Field

[0001] The present invention relates to the field of welding of check valves at the outlet of the nuclear power core makeup water tank, and particularly relates to a welding alignment tooling and a welding method for the check valve at the outlet of the core makeup water tank. Background Art

[0002] The core makeup water tank (abbreviated as CMT) of the AP1000 unit is used to provide long-term cooling injection flow to the pressure vessel under accident conditions. Two axial flow check valves are connected in series by welding on its outlet pipeline. The CMT outlet check valve belongs to an important primary nuclear power equipment. During the refueling outage overhaul, the operation test of the CMT outlet check valve is required to verify whether the position control function of the closing member of the CMT outlet check valve is normal when it is closed, fully opened or partially opened. Any check valve with a failed position control function during the test should be repaired or replaced.

[0003] The CMT outlet check valve is welded with a butt U-shaped weld and modularly installed on the outlet pipeline. The operating space around the CMT outlet check valve is extremely narrow. When carrying out its maintenance and replacement, the cutting work of the CMT outlet check valve must be carried out first, and the cut check valve is transported to the maintenance workshop for maintenance. In the prior art, due to the heavy weight of the CMT outlet check valve body, it is difficult to reliably align the weld lip of the valve body with the weld lip of the butt pipeline in a narrow space during automatic welding. Summary of the Invention

[0004] The present invention provides a welding alignment tooling and a welding method for the check valve at the outlet of the core makeup water tank, which are used to solve the problems of difficult welding and difficult alignment of the CMT outlet check valve body in the prior art.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention proposes a welding alignment tooling for the check valve at the outlet of the core makeup water tank. The tooling includes a frame, two pipeline fixing frames and a valve body support and adjustment frame. The frame provides a fixed basis for other components. A valve body support and adjustment frame is arranged at the center position of the frame, and two pipeline fixing frames are arranged at both ends of the frame; the valve body support and adjustment frame is used to support and adjust the horizontal position and vertical height of the check valve body, and the pipeline fixing frame is used to support and fix the check valve butt pipeline.

[0007] In some embodiments, the frame is welded with hollow profiles and the frame is a centrally symmetric structure.

[0008] In some embodiments, the valve body support adjustment frame includes two V-shaped support frames, a connecting plate, a fixed support, a vertical height adjustment mechanism, and a horizontal position adjustment mechanism. The two V-shaped support frames respectively support both sides of the check valve body. The lower ends of the V-shaped support frames are connected to the fixed support through the connecting plate. The lower end of the fixed support is provided with a horizontal position adjustment mechanism, and the vertical height adjustment mechanism is provided inside the fixed support.

[0009] In some embodiments, the horizontal position adjustment mechanism includes a sliding seat and a linear guide rail. The lower end of the fixed support is connected to the sliding seat. One end of the sliding seat is connected to the linear guide rail, and the other end of the linear guide rail is fixedly installed on the frame.

[0010] In some embodiments, the vertical height adjustment mechanism includes a worm gear lift, a bushing, and a guide shaft. The guide shaft is arranged inside the bushing. One end of the guide shaft is fixedly connected to the connecting plate, and the other end of the guide shaft is connected to the worm gear lift.

[0011] In some embodiments, each of the two pipe fixing frames respectively includes a pipe fixing frame A and a pipe fixing frame B. The pipe fixing frame A is installed on the outermost side of the frame and is used to support and fix the check valve docking pipe. The pipe fixing frame A is fixed to the frame through a nut; the pipe fixing frame B is installed inside the pipe fixing frame A and is used to support and fix one end of the check valve docking pipe close to the weld on the valve body side. The pipe fixing frame B is fixed to the frame through a nut.

[0012] In some embodiments, the pipe fixing frame A includes a V-shaped bracket A, side plates, a bottom plate, a channel steel pressing plate, and a screw rod pressing mechanism. The bottom plate and the side plates are connected through nuts. The V-shaped bracket A is arranged on the bottom plate and is used to support the check valve docking pipe. The top end of the side plate is connected to the channel steel pressing plate through a pin, and the screw rod pressing mechanism is arranged in the middle of the channel steel pressing plate.

[0013] In some embodiments, the screw rod pressing mechanism includes a screw rod, a screw nut, a handle, and a V-shaped top block. The V-shaped top block is arranged at the lower end of the channel steel pressing plate. The screw nut is arranged at the upper end of the V-shaped top block, and the upper end of the screw nut is connected to the screw rod. The handle is arranged on the screw rod.

[0014] In some embodiments, the pipe fixing frame B includes a V-shaped bracket B, an inner hexagon screw A, and an arc-shaped pressing plate. The arc-shaped pressing plate is arranged at the upper end of the check valve docking pipe, and the V-shaped bracket B is arranged at the lower end of the check valve docking pipe. The V-shaped bracket B is used to support the check valve docking pipe. The arc-shaped pressing plate and the V-shaped bracket B are fixed through the inner hexagon screw A.

[0015] The present invention provides a method for welding and butt-jointing a check valve at the outlet of a core makeup water tank. The method includes:

[0016] Step 1: Fix one side of the check valve docking pipe A on one side of the pipe fixing frame;

[0017] Step 2: Arrange the check valve body on the valve body support adjustment frame;

[0018] Step 3: Use the horizontal position adjustment mechanism and vertical height adjustment mechanism of the valve body support adjustment frame to adjust the position of the check valve body, so that the outer diameter of the weld of the check valve body and the docking pipe A of the check valve is concentric and the end face gap is less than 0.5 mm;

[0019] Step 4: Weld the check valve body and the docking pipe A of the check valve;

[0020] Step 5: Fix the other side of the check valve docking pipe B on the other side of the pipe fixing frame, adjust the position of the check valve docking pipe B, so that the end face weld of the check valve docking pipe B and the end face gap on the other side of the check valve body is less than 0.5 mm;

[0021] Step 6: Weld the check valve body and the docking pipe B of the check valve.

[0022] Implementing the present invention has the following beneficial effects:

[0023] The present invention proposes a welding butt joint tooling and welding method for the check valve at the outlet of the core makeup water tank. The butt joint tooling of the present invention adopts an integral frame and a centered symmetric layout structure design. A support adjustment frame for fixing the check valve body is installed in the middle, and two sets of pipe fixing frames are installed on both sides to fix the docking pipes, ensuring reliable fixation of the docking pipes. In the present invention, the valve body support adjustment frame is used to support and adjust the horizontal position and vertical height of the valve. A worm gear lifter and a guide post are installed inside the support to achieve arbitrary height adjustment and locking. The horizontal position adjustment mechanism relies on a linear guide rail and a slider to achieve free sliding, thereby realizing rapid centering of the weld lips of the CMT outlet check valve and the docking pipe, which can reduce the labor intensity of personnel and effectively improve work efficiency. Description of the Drawings

[0024] Figure 1 It is the front view of a welding butt joint tooling for the check valve at the outlet of the core makeup water tank proposed by the embodiment of the present invention;

[0025] Figure 2 It is the top view of a welding butt joint tooling for the check valve at the outlet of the core makeup water tank proposed by the embodiment of the present invention;

[0026] Figure 3 It is the schematic diagram of the pipe fixing frame A of a welding butt joint tooling for the check valve at the outlet of the core makeup water tank proposed by the embodiment of the present invention;

[0027] Figure 4 It is the schematic diagram of the pipe fixing frame B of a welding butt joint tooling for the check valve at the outlet of the core makeup water tank proposed by the embodiment of the present invention;

[0028] Figure 5Schematic diagram of a valve body support and adjustment frame for a welding butt joint tool for a check valve at the outlet of a core makeup water tank proposed in an embodiment of the present invention;

[0029] Description of the drawings: 1. Frame; 2. Pipe fixing bracket A; 3. Pipe fixing bracket B; 4. Pipe A; 5. Check valve body; 6. Valve body support and adjustment frame; 7. Pipe B; 8. Side locking nut; 9. Nut A; 10. Nut B; 11. V-shaped bracket A; 12. Pin; 13. Channel steel pressing plate; 14. Handle; 15. Lead screw; 16. Lead screw nut; 17. V-shaped top block; 18. V-shaped bracket B; 19. Hexagon socket head cap screw A; 20. Arc pressing plate; 21. V-shaped support frame; 22. Connecting plate; 23. Bush; 24. Fixed bracket; 25. Guide shaft; 26. Hexagon socket head cap screw B; 27. Slide block; 28. Linear guide rail; 29. Hexagon socket head cap screw C; 30. Hexagon socket head cap screw D; 31. Worm gear lifter. Detailed implementation manners

[0030] The technical solutions of the present invention will be clearly and completely described below in conjunction with the drawings and detailed implementation manners. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] As Figure 1 shown in the figure, the present invention proposes a welding butt joint tool for a check valve at the outlet of a core makeup water tank. The tool includes a frame 1, a pipe fixing bracket, and a valve body support and adjustment frame 6. The frame 1 provides a fixed foundation for other components. A valve body support and adjustment frame 6 is provided at the central position of the frame 1, and pipe fixing brackets are provided at both ends of the frame 1; the valve body support and adjustment frame 6 is used to support and adjust the horizontal position and vertical height of the check valve body 5, and the pipe fixing bracket is used to support and fix the butt joint pipes of the check valve. Other parts of the tool are all installed and fixed on the frame 1 and are hoisted and moved by a site crane. The conventional operation process of the butt joint tool is as follows: Use a crane to hoist the check valve body 5 and fix it to the valve body support and adjustment frame 6, hoist the butt joint pipe to the pipe fixing bracket and lock it, adjust the height of the valve body support frame for the butt joint of the weld lips of the valve body and the butt joint pipe, and after checking and measuring without problems, an automatic welding machine can be installed to carry out welding operations.

[0032] The frame 1 is the fixed foundation for other components. The frame 1 is welded from hollow profiles and is light and strong in structure. Since there are butt joint pipes at both the front and rear ends during the welding of the CMT outlet check valve, the frame 1 is designed with a centered and symmetric layout structure. The CMT outlet check valve body support and adjustment frame 6 is installed and fixed in the middle, and two sets of pipe fixing brackets are installed on both sides respectively to ensure the reliable fixation of the butt joint pipes.

[0033] As Figure 5As shown, the valve body support adjustment frame 6 is used to support and adjust the horizontal position and vertical height of the CMT outlet check valve body 5. It includes two V-shaped support frames 21, a connecting plate 22, a fixed support 24, a vertical height adjustment mechanism, and a horizontal position adjustment mechanism. To reliably support the valve body, two V-shaped support frames 21 are respectively arranged on both sides of the check valve body 5 to support the valve body. The lower ends of the V-shaped support frames 21 are connected to the fixed support 24 through the connecting plate 22. Horizontal position adjustment mechanisms are installed on both sides of the lower side of the fixed support 24. The slide block 27 of the horizontal position adjustment mechanism is connected to the lower end of the fixed support 24 through the hexagon socket head cap screw B26. One end of the linear guide rail 28 is connected to the lower part of the slide block 27 through the hexagon socket head cap screw C29, and the other end of the linear guide rail 28 is installed and fixed on the frame 1. A vertical height adjustment mechanism is arranged inside the fixed support 24. The vertical height adjustment mechanism includes a worm gear lift 31, a bushing 23, and a guide shaft 25. One end of the guide shaft 25 is fixed to the connecting plate 22, and the other end of the guide shaft 25 is connected to the worm gear lift 31 through the hexagon socket head cap screw D30. The bushing 23 is arranged outside the guide shaft 25. The height of the V-shaped support frame 21 is adjusted by operating the worm gear lift 31. The horizontal position adjustment mechanism is realized by relying on the linear guide rail 28 and the slide block 27.

[0034] As Figure 3 shown, each of the two pipe fixing frames respectively includes a pipe fixing frame A2 and a pipe fixing frame B3. The pipe fixing frame A2 is installed on the outermost side of the frame 1 and is used to support and fix the CMT outlet check valve docking pipe. The pipe fixing frame A2 is fixed to the frame 1 through the side locking nut 8 and the nut A9. The pipe fixing frame A2 includes a V-shaped bracket A11, side plates, a bottom plate, a channel steel pressing plate 13, and a screw rod 15 pressing mechanism. The bottom plate and the two side plates are respectively locked and fixed by 4 nuts. The V-shaped bracket A11 is arranged on the bottom plate and is used to support the check valve docking pipe. The top end of the side plate is connected to the channel steel pressing plate 13 through the pin 12, and the screw rod pressing mechanism is welded and installed in the middle of the channel steel pressing plate 13. The screw rod pressing mechanism includes a screw rod 15, a screw rod nut 16, a handle 14, and a V-shaped top block 17. The V-shaped top block 17 is arranged at the lower end of the channel steel pressing plate 13. The screw rod nut 16 is arranged at the upper end of the V-shaped top block 17, and the upper end of the screw rod nut 16 is connected to the screw rod 15. The screw rod 15 passes through the channel steel pressing plate 13, and the handle 14 is arranged on the screw rod 15. Operating the handle 14 at the top of the screw rod 15 to rotate and drive the bottom V-shaped top block 17 to press and release the pipe after passing through the nut fixed in the middle of the channel steel.

[0035] As Figure 4As shown, the pipe fixing frame B3 is installed on the inner side of the pipe fixing frame A2, and is used to support and fix the CMT outlet check valve butt joint pipe near the valve body weld. The pipe fixing frame B3 is fixed to the frame 1 by nuts B10. The pipe fixing frame B3 includes a V-shaped bracket B18, hexagon socket screws A19 and an arc pressure plate 20. The arc pressure plate 20 is arranged at the upper end of the check valve butt joint pipe, and the V-shaped bracket B18 is arranged at the lower end of the check valve butt joint pipe. The V-shaped bracket B18 is used to support the check valve butt joint pipe. The arc pressure plate 20 and the V-shaped bracket B18 are fixed by hexagon socket screws A19. The pipe fixing frame B3 also adopts a V-shaped support structure, and the supporting surface size is the same as that of the pipe fixing frame A2 to ensure the horizontality of the central axis of the pipe after support. The arc pressure plate 20 is connected and fixed to the V-shaped bracket B18 by 4 hexagon socket screws A19.

[0036] The present invention proposes a method for welding a check valve at an outlet of a core water supply tank, the method comprising:

[0037] Step 1: Fix the check valve on one side to the pipe A4 on the pipe fixing frame.

[0038] Step 1.1: Figure 1 As shown, the assembly is used for welding the counterpart tooling for the core water supply tank outlet check valve.

[0039] Step 1.2: Pull out the latch 12, and remove the channel steel pressure plate 13 and the parts thereon.

[0040] Step 1.3: Remove the hexagon socket screw A19 and take off the arc pressure plate 20.

[0041] Step 1.4: Lift the check valve to the connecting pipe A4 and arrange it on the V-shaped bracket A11 and V-shaped bracket B18.

[0042] Step 1.5: Install the channel steel pressure plate 13 and its components, and reinstall the latch 12.

[0043] Step 1.6: Rotate the handle 14 to push the V-shaped top block 17 against the pipe A4.

[0044] Step 1.7: Reinstall the arc pressure plate 20 and tighten the hexagon socket screw A19.

[0045] Step 2: hoist the check valve body 5 and arrange it on the V-shaped support frame 21 .

[0046] Step 3: Use the horizontal position adjustment mechanism and vertical height adjustment mechanism of the valve body support adjustment frame 6 to adjust the position of the check valve body 5, operate the worm gear elevator 31 to adjust the height of the check valve body 5, and at the same time push the fixed bracket 24 to drive the check valve body 5 to move along the linear guide rail 28 toward the weld of pipeline A4 until the outer diameters of the welds of the two are the same circle and the end face gap is less than 0.5mm.

[0047] Step 4: Weld the check valve body 5 and the check valve docking pipe A4. Install the automatic welding machine on the pipe A4. After starting and completing the weld, remove the automatic welding machine to complete the welding of the paired pipe on one side of the check valve.

[0048] Step 5: Fix the other check valve docking pipe B7 on the other pipe fixing bracket, and adjust the position of the check valve docking pipe B7 so that the end face weld gap between the check valve docking pipe B7 and the other end face of the check valve body 5 is less than 0.5 mm.

[0049] Step 5.1: Pull out the pin 12 on the other pipe fixing bracket, and remove the channel steel pressing plate 13 and its components on it.

[0050] Step 5.2: Remove the socket head cap screw A19 on the other pipe fixing bracket, and remove the arc-shaped pressing plate 20 on the other side.

[0051] Step 5.3: Lift and install the check valve docking pipe B7 on the V-shaped bracket A11 and V-shaped bracket B18 on the other pipe fixing bracket, and adjust it so that the end face weld gap is less than 0.5 mm from the end face of the check valve body 5.

[0052] Step 5.4: Install the channel steel pressing plate 13 and its components on the other pipe fixing bracket, and reinstall the pin 12 on the other pipe fixing bracket.

[0053] Step 5.5: Rotate the handle 14 on the other pipe fixing bracket to tighten the pressing top block on the other pipe fixing bracket against the pipe B7.

[0054] Step 5.6: Reinstall the arc-shaped pressing plate 20 on the other pipe fixing bracket, and lock the socket head cap screw A19 on the other pipe fixing bracket.

[0055] Step 6: Weld the check valve body 5 and the check valve docking pipe B7. Install the automatic welding machine on the check valve docking pipe B7. After starting and completing the weld, remove the automatic welding machine to complete the welding of the paired pipes of the check valve.

[0056] The present invention provides a welding butt joint tooling and a welding method for a check valve at the outlet of a core makeup water tank. The butt joint tooling of the present invention adopts an integral frame and a central symmetric layout structure design. A support and adjustment frame for fixing the check valve body is installed in the middle, and two sets of pipeline fixing frames are installed on both sides to fix the butt-jointed pipelines, ensuring the reliable fixation of the butt-jointed pipelines. In the present invention, the valve body support and adjustment frame is used to support and adjust the horizontal position and vertical height of the valve. A worm gear lifter and a guide post are installed inside the support to achieve arbitrary height adjustment and locking. The horizontal position adjustment mechanism relies on a linear guide rail and a slider to achieve free sliding, thereby realizing the rapid alignment of the weld lips of the CMT outlet check valve and the butt-jointed pipeline, which can reduce the labor intensity of personnel and effectively improve work efficiency.

[0057] The above embodiments only represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. A welding tool for the check valve at the outlet of the core water supply tank, characterized in that: The tooling comprises a frame (1), two pipe fixing frames and a valve body support adjustment frame (6); the frame (1) provides a fixing base for other components; the valve body support adjustment frame (6) is provided at the center of the frame (1); two pipe fixing frames are provided at both ends of the frame (1); the valve body support adjustment frame (6) is used to support and adjust the horizontal position and vertical height of the check valve body (5); and the pipe fixing frame is used to support and fix the check valve to the connecting pipe.

2. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 1 is characterized in that: The frame (1) is welded using hollow profiles, and the frame (1) is a centrally symmetrical structure.

3. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 1 is characterized in that: The valve body support adjustment frame (6) comprises two V-shaped support frames (21), a connecting plate (22), a fixed support (24), a vertical height adjustment mechanism and a horizontal position adjustment mechanism. The two V-shaped support frames (21) respectively support two sides of the check valve body (5). The lower end of the V-shaped support frame (21) is connected to the fixed support (24) via a connecting plate (22). The lower end of the fixed support (24) is provided with the horizontal position adjustment mechanism. The vertical height adjustment mechanism is provided inside the fixed support (24).

4. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 3 is characterized in that: The horizontal position adjustment mechanism comprises a slide (27) and a linear guide rail (28); the lower end of the fixed bracket (24) is connected to the slide (27); the slide (27) is connected to one end of the linear guide rail (28); and the other end of the linear guide rail (28) is fixedly mounted on the frame (1).

5. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 3 is characterized in that: The vertical height adjustment mechanism comprises a worm gear elevator (31), a shaft sleeve (23) and a guide shaft (25); one end of the guide shaft (23) is fixedly connected to the connecting plate (22); the other end of the guide shaft (25) is connected to the worm gear elevator (31); and the shaft sleeve (23) is arranged outside the shaft sleeve (23) of the guide shaft (25).

6. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 1 is characterized in that: Each of the two pipe fixing frames comprises a pipe fixing frame A (2) and a pipe fixing frame B (3), wherein the pipe fixing frame A (2) is mounted on the outermost side of the frame (1) and is used to support and fix the pipe connected to the check valve, and the pipe fixing frame A (2) is fixed to the frame (1) by nuts; the pipe fixing frame B (3) is mounted on the inner side of the pipe fixing frame A (2) and is used to support and fix one end of the pipe connected to the check valve close to the valve body side weld, and the pipe fixing frame B (3) is fixed to the frame (1) by nuts.

7. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 6 is characterized in that: The pipe fixing frame A (2) comprises a V-shaped bracket A (11), a side plate, a bottom plate, a channel steel pressure plate (13), and a screw rod (15) clamping mechanism. The bottom plate and the side plate are connected by nuts. The bottom plate is provided with a V-shaped bracket A (11), and the V-shaped bracket A (11) is used to support the check valve to connect the pipe. The top end of the side plate is connected to the channel steel pressure plate (13) by a latch (12), and the middle part of the channel steel pressure plate (13) is provided with a screw rod clamping mechanism.

8. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 7 is characterized in that: The screw rod clamping mechanism comprises a screw rod (15), a screw rod nut (16), a handle (14) and a V-shaped top block (17); the V-shaped top block (17) is arranged at the lower end of the channel steel pressing plate (13); the screw rod nut (16) is arranged at the upper end of the V-shaped top block (17); the upper end of the screw rod nut (16) is connected to the screw rod (15); the screw rod (15) passes through the channel steel pressing plate (13); and the handle (14) is arranged on the screw rod (15).

9. The welding tooling for the check valve at the outlet of the core water supply tank according to claim 7 is characterized in that: The pipe fixing frame B (3) comprises a V-shaped bracket B (18), a hexagon socket screw A (19) and an arc-shaped pressure plate (20), wherein the arc-shaped pressure plate (20) is arranged at the upper end of the check valve docking pipe, and the V-shaped bracket B (18) is arranged at the lower end of the check valve docking pipe. The V-shaped bracket B (18) is used to support the check valve docking pipe, and the arc-shaped pressure plate (20) and the V-shaped bracket B (18) are fixed by the hexagon socket screw A (19).

10. A method for welding a check valve at an outlet of a core water supply tank according to any one of claims 1 to 7, characterized in that: The method includes: Step 1: Fix the check valve at one side to the pipe A (4) on the pipe fixing bracket at one side; Step 2: Arrange the check valve body (5) on the valve body support and adjustment frame (6); Step 3: Use the horizontal position adjustment mechanism and the vertical height adjustment mechanism of the valve body support adjustment frame (6) to adjust the position of the check valve body (5) so that the outer diameters of the welds of the check valve body (5) and the check valve butt pipe A (4) are the same circle and the end face clearance is less than 0.5 mm; Step 4: welding the check valve body (5) and the check valve butt pipe A (4); Step 5: Fix the other side check valve butt pipe B (7) on the other side pipe fixing frame, and adjust the position of the check valve butt pipe B (7) so that the gap between the end face weld of the check valve butt pipe B (7) and the end face of the other side of the check valve body (5) is less than 0.5 mm; Step 6: Welding the check valve body (5) and the check valve butt pipe B (7).

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