A spherical container ring joint bevel welding method and a back gouging detection tool for nuclear power

Abstract

The application discloses a spherical container ring slit bevel welding method for nuclear power and a root clearance detection tool, and comprises the following steps: step 1: machining the bevels of upper head, cylinder melon petal assembly and lower head, the outer side bevels of the upper head and the lower head are perpendicular to the horizontal plane, the included angle between the inner side bevels of the upper head and the lower head and the outer side bevels is alpha, alpha is 115-125 degrees, the inner side bevels of the cylinder melon petal assembly are perpendicular to the horizontal plane, and the included angle between the outer side bevels and the inner side bevels of the cylinder melon petal assembly is also alpha, and the intersection of the outer side bevels and the inner side bevels is a vertex; step 2: welding the upper head, the cylinder melon petal assembly and the lower head, and oppositely arranging the vertex of the upper head or the lower head and the vertex of the cylinder melon petal assembly to perform ring welding; and step 3: after welding is completed, the welding surface is polished, visual detection, penetration detection and ray detection are performed on the finished welding.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plant nuclear island pressure vessel equipment manufacturing technology, specifically relating to a method for welding the circumferential groove of a spherical container for nuclear power and a root cleaning and inspection tool. Background Technology

[0002] The "Hualong One" spherical safety injection tank is one of the important pieces of equipment in the passive core cooling system of a nuclear power plant. Its main function is to provide boric acid solution in the event of a loss-of-coolant accident in the primary circuit to keep the reactor in a safe shutdown state, which plays an important role in improving the safety and reliability of the nuclear power plant reactor system.

[0003] Compared to the vertical cylindrical safety injection tanks used in early nuclear power plants, spherical safety injection tanks offer several advantages, including smaller footprint, higher site utilization in reactor building layouts, and the lowest mass under the same pressure and volume conditions. Currently, some equipment in domestic nuclear power technologies such as AP1000 and Hualong One utilizes spherical container designs. One of the most critical aspects of manufacturing spherical equipment is controlling weld quality. The welding quality of the circumferential welds between the upper and lower end caps and the cylindrical segment assembly is a key factor affecting the overall quality of the equipment.

[0004] The existing welding method for spherical injection boxes is as follows: the welding bevel of the spherical injection box is designed as a centripetal symmetrical double U-shaped bevel. During welding, a positioner is required to adjust the equipment weld to the flat welding position for welding. The equipment is large in size and heavy in weight, and special clamping fixtures are required to connect the equipment and the positioner. The fixture structure is complex, and it also increases the difficulty of cleaning the back of the weld during the welding process, making it difficult to guarantee the welding quality. Incomplete cleaning leads to uncontrollable final weld quality.

[0005] The original design of the bevel was difficult to achieve the welding requirements by machining it on a lathe alone. It also required manual grinding and other measures to adjust the shape and size of the bevel in order to meet the welding requirements. Even with the easy-to-machine double V-groove, the conventional bevel form is a symmetrical bevel. During welding, a positioner is required to flip the weld to the flat welding position. The auxiliary equipment is complicated and the welding is difficult, which is not conducive to ensuring the quality of the weld.

[0006] Currently, the rework rate of circumferential welds in spherical injection boxes is high. Statistics show that the lowest pass rate for this weld on the first piece of equipment was 83.7%, the highest pass rate was 95.2%, and the average pass rate was 90.95%. The rework cycle for each weld is 3 to 4 working days. Due to the large size and special structure of spherical injection boxes, the traditional process for circumferential weld welding has disadvantages such as high welding difficulty, complex auxiliary equipment, and low pass rate of radiographic testing of welds. Therefore, it is necessary to optimize and adjust the traditional process to improve the welding quality of circumferential welds. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for welding the circumferential groove of a spherical container for nuclear power plants and a root cleaning and inspection tool.

[0008] This invention discloses a method for beveling the circumferential seam of a spherical container for nuclear power plants, comprising the following steps:

[0009] Step 1: Process the bevels of the upper end cap, the cylindrical melon-shaped assembly, and the lower end cap. The outer bevels of the upper and lower end caps are perpendicular to the horizontal plane. The angle between the inner and outer bevels of the upper and lower end caps is α, where α is 115° to 125°. The inner bevel of the cylindrical melon-shaped assembly is perpendicular to the horizontal plane. The angle between the outer and inner bevels of the cylindrical melon-shaped assembly is also α. The intersection of the outer and inner bevels is the vertex.

[0010] Step 2: Weld the upper end cap, the cylindrical petal assembly, and the lower end cap, and align the apex of the upper or lower end cap with the apex of the cylindrical petal assembly to perform a circumferential weld;

[0011] Step 3: After welding is completed, the weld surface is ground and the completed weld is visually inspected, penetrant tested and radiographic tested.

[0012] Preferably, step 1 includes:

[0013] Step 1-1: Place the upper and lower end caps with their open ends facing down on the machine tool. Use the open ends of the upper and lower end caps as a rough reference to level and align the workpiece. Turn the outer bevels of the upper and lower end caps. The outer bevels of the end caps are perpendicular to the horizontal plane.

[0014] Step 1-2: Turn the inner bevel of the upper and lower heads. The intersection of the outer and inner bevels of the heads is the vertex, and the included angle between the inner and outer bevels is α.

[0015] Steps 1-3: Match the end diameters of the upper and lower end caps with the end diameters of the cylindrical melon-shaped assembly to ensure that the upper and lower end caps are concentric and perpendicular to the waistline of the waist drum of the cylindrical melon-shaped assembly;

[0016] Steps 1-4: Place the cylindrical melon-shaped assembly vertically on the machine tool, level and align the workpiece, and turn the inner bevels of the upper and lower ends of the cylindrical melon-shaped assembly. The inner bevels of the cylindrical assembly are perpendicular to the horizontal plane.

[0017] Steps 1-5: Turn the outer bevels of the upper and lower ends of the cylinder segment assembly. The angle between the outer bevel and the inner bevel of the cylinder is α.

[0018] Preferably, the inner bevel of the upper or lower end cap is machined at 1 / 3 of the thickness of the upper or lower end cap from the outside to the inside.

[0019] Preferably, the outer bevel of the cylindrical melon-shaped assembly is machined at 1 / 3 of the thickness of the assembly from the outside to the inside.

[0020] Preferably, the included angle α is 120°.

[0021] Preferably, step 2 includes:

[0022] Step 2-1: Set the upper end cap on the lower side with the open end facing upwards, and set the cylindrical petal assembly on the upper side, so that the straight line of the outer bevel of the upper end cap is parallel to the straight line of the inner bevel of the cylindrical petal assembly, and set the vertex of the upper end cap opposite to one vertex of the cylindrical petal assembly. At the same time, ensure that the upper end cap and the waist drum circle of the cylindrical petal assembly are concentric and perpendicular to the waist line. Then, spot weld and fix them between the outer bevel of the cylindrical petal assembly and the outer bevel of the upper end cap.

[0023] Step 2-2: Use shielded metal arc welding to perform spot welding and fill welding on the inner bevel of the cylinder and the inner bevel of the upper end cap of the cylinder lobe assembly until the bevel is fully welded. The welding position is the flat welding position.

[0024] Steps 2-3: Flip the welded upper head and the cylindrical petal assembly, with the lower head positioned on the bottom. Align the outer bevel line of the lower head with the inner bevel line of the cylindrical petal assembly, and align the apex of the lower head with the other apex of the cylindrical petal assembly. Ensure the lower head and the waistline of the cylindrical petal assembly are concentric and perpendicular. Perform tack welding and fill welding using shielded metal arc welding within the inner bevel of the cylindrical petal assembly and the inner bevel of the lower head until the bevels are fully welded. The welding position is a flat weld. Simultaneously, use a stainless steel grinding tool to clean the outer side of the weld between the upper head and the cylindrical petal assembly through the space between the outer bevel of the cylindrical body and the outer bevel of the head. After removing the root weld, use a root cleaning inspection tool to check the dimensions of the outer bevel after root cleaning, ensuring the tool can be fully placed within the outer bevel.

[0025] Steps 2-4: Use shielded metal arc welding to perform spot welding and fill welding on the outer bevel of the upper head and the inner bevel of the cylinder petal assembly until the bevel is fully welded. The welding position is the flat welding position.

[0026] Steps 2-5: Turn over the upper head, the cylinder petal assembly and the lower head that have been welded together. Use a special stainless steel grinding tool to clean the outer side of the weld between the lower head and the cylinder petal assembly from the space between the outer bevel of the cylinder and the outer bevel of the head. After removing the root weld, use a root cleaning inspection tool to check the size of the outer bevel after root cleaning, so that the root cleaning inspection tool can be completely placed in the outer bevel.

[0027] Steps 2-6: Use shielded metal arc welding to perform spot welding and fill welding on the outer bevel of the lower head and the outer bevel of the cylinder segment assembly until the bevel is fully welded. The welding position is the flat welding position.

[0028] Preferably, the vertex of the upper or lower end cap is opposite to the vertex of the cylindrical melon-shaped assembly, and the distance between the vertex of the upper or lower end cap and the vertex of the cylindrical melon-shaped assembly is 2-3 mm.

[0029] Preferably, a root cleaning inspection tool is used to check the outer bevel size after root cleaning in a circumferential bevel welding method for spherical containers used in nuclear power plants. The root cleaning inspection tool includes a root cleaning inspection part and a handheld part. The top of the root cleaning inspection part is connected to the handheld part. The root cleaning inspection part is a conical structure with a rounded end transition. The outer wall of the large-diameter end of the root cleaning inspection part is provided with a size inspection scale line.

[0030] Preferably, in steps 2-3 and 2-5, the root cleaning detection tool can be completely placed in the outer bevel. Specifically, the root cleaning detection part is placed in the outer bevel, so that the lower scale line of the root cleaning detection part is flush with or lower than the straight line between the upper or lower end cap and the outer surface of the cylinder segment assembly, or the upper scale line of the root cleaning detection part is higher than the straight line between the upper or lower end cap and the outer surface of the cylinder segment assembly.

[0031] Preferably, the width of the size detection scale line is 2 to 6 mm.

[0032] Compared with the prior art, the advantages of the present invention are as follows:

[0033] (1) This invention discloses a method for welding the bevel of the circumferential seam of a spherical container for nuclear power. The outer bevels of the upper and lower end caps are perpendicular to the horizontal plane, and the angle between the inner and outer bevels of the upper and lower end caps is α. The inner bevel of the cylindrical petal assembly is perpendicular to the horizontal plane, and the angle between the outer and inner bevels of the cylindrical petal assembly is also α. α is 115° to 125°. This bevel form is exactly based on the shape of the spherical container. The angle between the bevel angle at the circumferential seam position and the center line of the spherical container is controlled within 65°. The weld can be welded in the flat welding position without the assistance of a positioner. This invention optimizes the bevel form and size of the circumferential weld, reduces the difficulty of bevel processing, makes the bevel size easier to guarantee, and is conducive to improving the welding quality of the weld. When the circumferential seam of the product is welded according to the improvement measures of this invention, the pass rate of the weld radiographic inspection after welding is higher than 99%.

[0034] (2) When processing the bevels of the upper end cap, the cylindrical melon-shaped assembly and the lower end cap, the present invention only requires the upper end cap and the lower end cap to be placed horizontally, or the cylindrical melon-shaped assembly to be placed vertically on the machine tool. It is easy to position during processing. One side only needs to be processed into a bevel perpendicular to the horizontal plane, and the other side can be directly beveled at 55-65°. The bevel size measurement is simple and convenient. The bevel forms of the components that are welded to the upper end cap or the lower end cap and the cylindrical melon-shaped assembly are opposite. They can cooperate with each other to obtain the best welding position. The present invention effectively reduces the difficulty of machining the bevels of the upper end cap, the lower end cap and the cylindrical melon-shaped assembly, and greatly reduces the difficulty of clamping the equipment.

[0035] (3) The bevel form disclosed in this invention can realize the horizontal placement of the workpiece when welding the circumferential weld, without the need for other auxiliary tooling to adjust the welding position. Therefore, when welding a single weld, multiple people can weld at the same time, which effectively improves the welding efficiency. At the same time, welding deformation can be controlled by segmented skip welding, which is conducive to ensuring the overall size of the equipment.

[0036] (4) The inner bevel machining position of the upper or lower end cap is at 1 / 3 of the thickness of the upper or lower end cap from the outside to the inside, and the outer bevel machining position of the cylindrical petal assembly is at 1 / 3 of the thickness of the cylindrical petal assembly from the outside to the inside. This ensures that the thickness of the outer bevel after welding is 1 / 3 of the thickness of the spherical container, and the thickness of the inner bevel after welding is 2 / 3 of the thickness of the spherical container, thus ensuring the welding strength at the weld.

[0037] (5) This invention discloses a root cleaning inspection tool. The root cleaning inspection tool is designed with a size inspection scale line, which can measure the bevel depth, bevel angle and root flatness after root cleaning. The root cleaning inspection part is placed in the outer bevel, so that the lower scale line of the root cleaning inspection part is flush with or lower than the straight line between the upper or lower end cap and the outer surface of the cylinder segment assembly, or the upper scale line of the root cleaning inspection part is higher than the straight line between the upper or lower end cap and the outer surface of the cylinder segment assembly. Therefore, when the root cleaning inspection tool is completely placed in the outer bevel, the root cleaning depth can be guaranteed, so as to ensure that defects such as incomplete penetration, incomplete fusion and poor forming of the root can be thoroughly removed, and the root cleaning quality can meet the welding requirements, providing the best welding conditions for subsequent welding. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the spherical container for nuclear power plants according to the present invention;

[0039] Figure 2 This is a schematic diagram of the bevel joint of the circumferential weld between the upper or lower end cap and the cylindrical petal assembly of the present invention.

[0040] Figure 3 This is a schematic diagram of the root clearing detection tool of the present invention;

[0041] Figure 4 This is a schematic diagram illustrating the use of the root clearing detection tool of the present invention.

[0042] Explanation of reference numerals in the attached figures:

[0043] 1. Upper head, 2. Cylinder body petal assembly, 3. Lower head, 4. Circumferential weld, 5. Root cleaning inspection tool, 6. Dimension inspection scale line, 7. Inner bevel of cylinder, 8. Outer bevel of cylinder, 9. Outer bevel of head, 10. Inner bevel of head, 11. Vertex.

[0044] 5-1. Root cleaning and detection section; 5-2. Handheld section. Detailed Implementation

[0045] The specific implementation of the present invention is described below with reference to embodiments:

[0046] It should be noted that the structures, proportions, sizes, etc. shown in this specification are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0047] Example 1

[0048] like Figure 1 As shown, this invention discloses a method for beveling the circumferential seam of a spherical container for nuclear power plants, comprising the following steps:

[0049] Step 1: Process the bevels of the upper end cap 1, the cylindrical melon-shaped assembly 2, and the lower end cap 3. The outer bevels of the upper end cap 1 and the lower end cap 3 are perpendicular to the horizontal plane. The angle between the inner and outer bevels of the upper end cap 1 and the lower end cap 3 is α, where α is 115° to 125°. The inner bevel of the cylindrical melon-shaped assembly 2 is perpendicular to the horizontal plane. The angle between the outer and inner bevels of the cylindrical melon-shaped assembly 2 is also α. The intersection of the outer and inner bevels is vertex 11.

[0050] Step 2: Weld the upper end cap 1, the cylindrical petal assembly 2 and the lower end cap 3, and circumferentially weld the apex 11 of the upper end cap 1 or the lower end cap 3 with the apex 11 of the cylindrical petal assembly 2.

[0051] Step 3: After welding is completed, the weld surface is ground and the completed weld is visually inspected, penetrant tested and radiographic tested.

[0052] When α is 115° to 125°, that is, the angle between the inner bevels of the upper end cap 1 and the lower end cap 3 and the vertical line is 55° to 65°, and the angle between the outer bevel of the cylinder melon-shaped assembly 2 and the vertical line is 55° to 65°.

[0053] Example 2

[0054] like Figure 2 As shown, preferably, step 1 includes:

[0055] Step 1-1: Place the upper head 1 and the lower head 3 with their open ends facing down on the machine tool. Use the open ends of the upper head 1 and the lower head 3 as a rough reference to level and align the workpiece. Turn the outer bevel 9 of the upper head 1 and the lower head 3. The outer bevel 9 of the head is perpendicular to the horizontal plane.

[0056] Step 1-2: Turn the inner bevel 10 of the upper head 1 and the lower head 3. The intersection of the outer bevel 9 and the inner bevel 10 is the vertex 11, and the included angle between the inner bevel 10 and the outer bevel 9 is α.

[0057] Steps 1-3: Match the end diameters of the upper end cap 1 and the lower end cap 3 with the end diameter of the cylindrical melon-shaped assembly 2 to ensure that the upper end cap 1, the lower end cap 3 and the waist drum circle of the cylindrical melon-shaped assembly 2 are concentric and perpendicular to the waist line.

[0058] Steps 1-4: Place the cylindrical melon-shaped assembly 2 vertically on the machine tool, level and align the workpiece, and turn the inner bevel 7 of the upper and lower ends of the cylindrical melon-shaped assembly 2. The inner bevel 7 of the cylindrical melon-shaped assembly 2 is perpendicular to the horizontal plane.

[0059] Steps 1-5: Turn the outer bevel 8 of the upper and lower ends of the cylinder segment assembly 2. The included angle between the outer bevel 8 and the inner bevel 7 of the cylinder is α.

[0060] Preferably, the inner bevel 10 of the upper end cap 1 or lower end cap 3 is machined at 1 / 3 of the thickness of the upper end cap 1 or lower end cap 3 from the outside to the inside.

[0061] Preferably, the outer bevel 8 of the cylindrical melon-shaped assembly 2 is machined at 1 / 3 of the thickness of the cylindrical melon-shaped assembly 2 from the outside to the inside.

[0062] Preferably, the included angle α is 120°, that is, the included angle between the inner bevels of the upper end cap 1 and the lower end cap 3 and the vertical line is 60°, and the included angle between the outer bevel of the cylindrical melon-shaped assembly 2 and the vertical line is 60°.

[0063] Example 3

[0064] like Figure 2 , 4 As shown, preferably, step 2 includes:

[0065] Step 2-1: Set the upper end cap 1 on the lower side with the open end facing upward, and set the cylindrical petal assembly 2 on the upper side, so that the straight line of the outer bevel 9 of the upper end cap 1 is parallel to the straight line of the inner bevel 7 of the cylindrical petal assembly 2, and set the vertex 11 of the upper end cap 1 opposite to one vertex 11 of the cylindrical petal assembly 2. At the same time, ensure that the waistline of the upper end cap 1 and the waist drum of the cylindrical petal assembly 2 are concentric and perpendicular. Then, spot weld and fix it between the outer bevel 8 of the cylindrical petal assembly 2 and the outer bevel 9 of the upper end cap 1.

[0066] Step 2-2: Use shielded metal arc welding to perform spot welding and fill welding in the inner bevel 7 of the cylinder body melon-shaped assembly 2 and the inner bevel 10 of the upper end cap 1 until the bevel is fully welded. The welding position is the flat welding position.

[0067] Steps 2-3: Flip the welded upper head 1 and the cylindrical petal assembly 2, with the lower head 3 positioned on the lower side. Align the straight line of the outer bevel 9 of the lower head 3 with the straight line of the inner bevel 7 of the cylindrical petal assembly 2, and align the apex 11 of the lower head 3 with the other apex 11 of the cylindrical petal assembly 2. Ensure that the lower head 3 and the waist drum circle of the cylindrical petal assembly 2 are concentric and perpendicular. Perform spot welding and fill welding using shielded metal arc welding within the inner bevel 7 of the cylindrical petal assembly 2 and the inner bevel 10 of the lower head 3, until the bevels are fully welded. The welding position is a flat weld position. Simultaneously, use a stainless steel special grinding tool to perform root cleaning and grinding on the outside of the weld between the upper head 1 and the cylindrical petal assembly 2 through the space between the outer bevel 8 of the cylindrical body and the outer bevel 9 of the head. After removing the root weld, use a root cleaning inspection tool 5 to check the size of the outer bevel after root cleaning, ensuring that the root cleaning inspection tool 5 can be completely placed in the outer bevel.

[0068] Steps 2-4: Use shielded metal arc welding to perform spot welding and fill welding on the outer bevel 9 of the upper head 1 and the outer bevel 8 of the cylinder petal assembly 2 until the bevel is fully welded. The welding position is the flat welding position.

[0069] Steps 2-5: Turn over the upper head 1, the cylinder petal assembly 2 and the lower head 3 that have been welded together. Use a special stainless steel grinding tool to clean the outer side of the weld between the lower head 3 and the cylinder petal assembly 2 from the space between the outer bevel 8 of the cylinder and the outer bevel 9 of the head. After removing the root weld, use a root cleaning inspection tool 5 to check the size of the outer bevel after root cleaning, so that the root cleaning inspection tool 5 can be completely placed in the outer bevel.

[0070] Steps 2-6: Use shielded metal arc welding to perform spot welding and fill welding on the outer bevel 9 of the lower end cap 3 and the outer bevel 8 of the cylinder lobe assembly 2 until the bevel is fully welded. The welding position is the flat welding position.

[0071] Preferably, the vertex 11 of the upper end cap 1 or the lower end cap 3 is opposite to the vertex 11 of the cylindrical melon-shaped assembly 2, and the distance between the vertex 11 of the upper end cap 1 or the lower end cap 3 and the vertex 11 of the cylindrical melon-shaped assembly 2 is 2-3 mm.

[0072] The quality of the beveling assembly is closely related to the ellipticity of the rear end of the cylindrical petal assembly welded together. Ellipticity deviation directly affects the machining dimensions of the circumferential beveling, thus impacting the assembly and welding quality. Therefore, when welding the cylindrical petal assembly, it is essential to strictly adhere to the specified welding parameters and employ a symmetrical welding method to minimize ellipticity deviations caused by welding deformation. Furthermore, before machining the beveling of the upper and lower end caps and the cylindrical petal assembly, end dimension measurements should be performed. The beveling dimensions of the end caps should be matched to the actual dimensions of the petals. For any unmachined beveling areas, grinding should be performed after assembly to ensure the beveling depth, thereby reducing misalignment and ultimately ensuring the welding quality of the root weld.

[0073] Since the circumferential weld 4 is a single-curved surface, the shape has a certain deviation after being formed by large-size equipment. The amount of back cleaning processing using mechanical processing equipment cannot be adjusted in real time, and the cleaning quality cannot meet the requirements of subsequent welding. The best solution is still manual grinding. This invention uses a special stainless steel grinding tool (existing tool), which can be adjusted in time according to the situation of the root welding during the grinding process to ensure thorough cleaning and provide the best welding conditions for subsequent welding.

[0074] Example 4

[0075] like Figure 3 As shown, a preferred root cleaning inspection tool is used to check the outer bevel size after root cleaning in a circumferential bevel welding method for spherical containers used in nuclear power plants. The root cleaning inspection tool 5 includes a root cleaning inspection part 5-1 and a handheld part 5-2. The top of the root cleaning inspection part 5-1 is connected to the handheld part 5-2. The root cleaning inspection part 5-1 is a conical structure with a rounded end transition. The outer wall of the large-diameter end of the root cleaning inspection part 5-1 is provided with a size inspection scale line 6.

[0076] Since the width and flatness of the root bevel after root cleaning have a significant impact on subsequent welding, they should be strictly controlled. There are certain variables when assembling weld bevels, and the possibility of ensuring full penetration and good formation during root shielded metal arc welding is extremely small. Therefore, the root cleaning depth also needs to be controlled. When the root cleaning detection tool 5 of this invention is fully placed in the outer bevel, it can ensure the root cleaning depth, so as to ensure that defects such as incomplete penetration, lack of fusion and poor formation at the root can be thoroughly removed, providing the best welding conditions for subsequent welding.

[0077] like Figure 4As shown, preferably, in steps 2-3 and 2-5, the root cleaning detection tool 5 can be completely placed in the outer bevel. Specifically, the root cleaning detection part 5-1 is placed in the outer bevel, so that the lower scale line of the root cleaning detection part 5-1 is flush with or lower than the straight line between the upper end cap 1 or the lower end cap 3 and the outer surface of the cylinder melon-shaped assembly 2, or the upper scale line of the root cleaning detection part 5-1 is higher than the straight line between the upper end cap 1 or the lower end cap 3 and the outer surface of the cylinder melon-shaped assembly 2.

[0078] Preferably, the width of the size detection scale line 6 is 2 to 6 mm.

[0079] Example 5

[0080] Step 1: Process the bevels of the upper end cap 1, the cylindrical melon-shaped assembly 2, and the lower end cap 3.

[0081] Step 1-1: Place the upper head 1 and the lower head 3 on the machine tool, use the open end as a rough reference to level and align the workpiece, verify and turn the outer bevel 9 of the upper head 1 and the lower head 3. No further beveling is required. The outer bevel 9 of the head is perpendicular to the horizontal plane.

[0082] Steps 1-2: Check the actual thickness, turn the inner bevel 10 of the upper head 1 and the lower head 3, and the included angle between the inner bevel 10 of the middle head and the outer bevel 9 of the head is 120°.

[0083] Steps 1-3: Match the end diameters (outermost) of the upper end cap 1 and the lower end cap 3 with the end diameter of the cylindrical melon-shaped assembly 2 to ensure that the upper end cap 1, the lower end cap 3 and the waist drum circle of the cylindrical melon-shaped assembly 2 are concentric and perpendicular to the waist line.

[0084] Steps 1-4: Place the cylindrical melon-shaped assembly 2 vertically on the machine tool, level and align the workpiece, and turn the inner bevel 7 of the upper and lower ends of the cylindrical melon-shaped assembly 2. No further beveling is required. The inner bevel 7 of the cylindrical body is perpendicular to the horizontal plane.

[0085] Steps 1-5: Turn the outer bevel 8 of the upper and lower ends of the cylinder segment assembly 2. The included angle between the outer bevel 8 and the inner bevel 7 of the cylinder is 120°.

[0086] Step 2: Weld the upper end cap 1, the cylinder lobe assembly 2, and the lower end cap 3.

[0087] Step 2-1: With the upper end cap 1 at the bottom and the cylindrical melon-shaped assembly 2 at the top, make the straight line of the outer bevel 9 of the upper end cap 1 parallel to the straight line of the inner bevel 7 of the cylindrical melon-shaped assembly 2, and make the vertex 11 of the upper end cap 1 opposite to one vertex 11 of the cylindrical melon-shaped assembly 2. At the same time, ensure that the waistline of the upper end cap 1 and the waist drum circle of the cylindrical melon-shaped assembly 2 are perpendicular to each other. Then, spot weld and fix them between the outer bevel 8 of the cylindrical melon-shaped assembly 2 and the outer bevel 9 of the upper end cap 1.

[0088] Step 2-2: Use shielded metal arc welding to perform spot welding and fill welding in the inner bevel 7 of the cylinder body melon-shaped assembly 2 and the inner bevel 10 of the upper end cap 1 until the bevel is fully welded. The welding position is the flat welding position.

[0089] Steps 2-3: Flip the welded upper head 1 and the cylindrical petal assembly 2, with the lower head 3 at the bottom. Align the straight line of the outer bevel 9 of the lower head 3 with the straight line of the inner bevel 7 of the cylindrical petal assembly 2, and align the apex 11 of the lower head 3 with the other apex 11 of the cylindrical petal assembly 2. Ensure that the waistline of the lower head 3 and the waist drum of the cylindrical petal assembly 2 are concentric and perpendicular. Use shielded metal arc welding to perform spot welding and fill welding within the inner bevel 7 of the cylindrical petal assembly 2 and the inner bevel 10 of the lower head 3 until the bevel is fully welded. The welding position is a flat welding position. At the same time, use a stainless steel special grinding tool to perform root cleaning and grinding on the outside of the weld between the upper head 1 and the cylindrical petal assembly 2 through the space between the outer bevel 8 of the cylindrical body and the outer bevel 9 of the head. After removing the root weld, use a root cleaning inspection tool 5 to check the size of the outer bevel after root cleaning, ensuring that the root cleaning inspection tool 5 can be completely placed in the outer bevel.

[0090] Steps 2-4: Weld the outer bevels of the upper end cap 1 and the cylindrical petal assembly 2;

[0091] Steps 2-5: Turn over the upper and lower end caps and the cylinder petal assembly 2 that have been welded together. Use a special stainless steel grinding tool to clean the outside of the weld between the lower end cap 3 and the cylinder petal assembly 2 from the space between the outer bevel 8 of the cylinder and the outer bevel 9 of the end cap. After removing the root weld, use a root cleaning inspection tool 5 to check the size of the outer bevel after root cleaning, so that the root cleaning inspection tool 5 can be completely placed in the outer bevel.

[0092] Steps 2-6: Use shielded metal arc welding to perform spot welding and fill welding on the outer bevel 9 of the lower end cap 3 and the outer bevel 8 of the cylinder petal assembly 2 until the bevel is fully welded. The welding position is the flat welding position.

[0093] Step 3: The thickness of the circumferential weld 4 is about 70mm and the diameter is about 4m. After welding, the weld surface is ground to meet the requirements of the drawings. Visual inspection, penetrant testing and radiographic testing are carried out on the completed weld according to the relevant technical requirements.

[0094] By using the circumferential weld bevel welding method for spherical containers for nuclear power plants of the present invention and taking the above welding measures, the pass rate of radiographic testing of 11 units has been greatly improved. Most circumferential welds passed radiographic testing on the first attempt, with a minimum pass rate of 96.0% and a maximum pass rate of 100%. The average pass rate of radiographic testing of welds is higher than 99.4%.

[0095] The principle of this invention is as follows:

[0096] like Figures 1-4 As shown, this invention discloses a method for beveling the circumferential seam of a spherical container for nuclear power plants. Step 1: Process the bevels of the upper head 1, the cylindrical segmented assembly 2, and the lower head 3. The outer bevels of the upper head 1 and the lower head 3 are perpendicular to the horizontal plane. The angle between the inner and outer bevels of the upper head 1 and the lower head 3 is α, where α is 115°–125°. The inner bevel of the cylindrical segmented assembly 2 is perpendicular to the horizontal plane. The angle between the outer and inner bevels of the cylindrical segmented assembly 2 is also α. The intersection of the outer and inner bevels is vertex 11. Step 2: Weld the upper head 1, the cylindrical segmented assembly 2, and the lower head 3. Step 3: After welding, the weld surface is ground, and the completed weld is visually inspected, penetrant tested, and radiographically inspected. By analyzing the causes of welding defects in the spherical container circumferential weld, optimization and improvement measures are formulated for each influencing factor to improve the welding quality of the circumferential weld. By optimizing the welding groove form and size of the circumferential weld, the difficulty of groove processing is reduced, the groove size is easier to guarantee, and the welding quality of the weld is improved. By designing and manufacturing root cleaning inspection tools, the root cleaning quality is ensured.

[0097] This invention discloses a method for beveling the circumferential seam of a spherical container for nuclear power plants. The outer bevels of the upper and lower end caps are perpendicular to the horizontal plane, and the angle between the inner and outer bevels of the upper and lower end caps is α. The inner bevel of the cylindrical lobed assembly is perpendicular to the horizontal plane, and the angle between the outer and inner bevels of the cylindrical lobed assembly is also α, where α is 115°–125°. This bevel configuration is precisely based on the shape of the spherical container, controlling the angle between the bevel at the circumferential seam and the centerline of the spherical container within a 65° range. The weld can be performed in a flat welding position without the assistance of a positioner. This invention optimizes the bevel configuration and dimensions of the circumferential weld, reduces the difficulty of bevel processing, makes it easier to guarantee the bevel dimensions, and improves the weld quality. When the circumferential seam is welded according to the improved measures of this invention, the pass rate of radiographic testing of the weld after welding is higher than 99%.

[0098] When processing the beveling of the upper end cap, the cylindrical melon-shaped assembly, and the lower end cap, this invention only requires placing the upper and lower end caps horizontally, or placing the cylindrical melon-shaped assembly vertically on the machine tool. This makes positioning easy during processing. One side only needs to be processed into a beveling perpendicular to the horizontal plane, while the other side can be directly chamfered at 55-65°. Beveling size measurement is simple and convenient. The beveling forms of the components that are butt-welded to the upper or lower end cap and the cylindrical melon-shaped assembly are opposite, and their mutual cooperation can obtain the optimal welding position. This invention effectively reduces the difficulty of machining the beveling of individual upper end caps, lower end caps, and cylindrical melon-shaped assemblies, and also greatly reduces the difficulty of equipment clamping.

[0099] The bevel design disclosed in this invention allows the workpiece to be placed horizontally during circumferential weld welding without the need for other auxiliary tooling to adjust the welding position. Therefore, multiple people can weld simultaneously when welding a single weld, effectively improving welding efficiency. At the same time, welding deformation can be controlled by segmented skip welding, which helps to ensure the overall size of the equipment.

[0100] In this invention, the inner bevel machining position of the upper or lower end cap is at 1 / 3 of the thickness of the upper or lower end cap from the outside to the inside, and the outer bevel machining position of the cylindrical petal assembly is at 1 / 3 of the thickness of the cylindrical petal assembly from the outside to the inside. This ensures that the thickness of the outer bevel after welding is 1 / 3 of the thickness of the spherical container, and the thickness of the inner bevel after welding is 2 / 3 of the thickness of the spherical container, thus ensuring the welding strength at the weld.

[0101] This invention discloses a root cleaning inspection tool. The tool is designed with a dimensional measurement scale strip to measure the bevel depth, bevel angle, and root flatness after root cleaning. The root cleaning inspection part is placed in the outer bevel, with the lower scale line of the inspection part flush with or lower than the straight line between the upper or lower end cap and the outer surface of the cylinder segment assembly, or the upper scale line of the inspection part higher than the straight line between the upper or lower end cap and the outer surface of the cylinder segment assembly. Therefore, when the root cleaning inspection tool is fully placed in the outer bevel, the root cleaning depth can be guaranteed, ensuring that defects such as incomplete penetration, lack of fusion, and poor forming at the root can be thoroughly removed, ensuring that the root cleaning quality meets the welding requirements and providing optimal welding conditions for subsequent welding.

[0102] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

[0103] Many other changes and modifications can be made without departing from the concept and scope of this invention. It should be understood that this invention is not limited to the specific embodiments, and the scope of this invention is defined by the appended claims.

Claims

1. A method for beveling the circumferential seam of a spherical container for nuclear power plants, characterized in that, Includes the following steps, Step 1: Process the bevels of the upper end cap (1), the cylindrical melon-shaped assembly (2) and the lower end cap (3). The outer bevels of the upper end cap (1) and the lower end cap (3) are perpendicular to the horizontal plane. The angle between the inner and outer bevels of the upper end cap (1) and the lower end cap (3) is α, where α is 115°~125°. The inner bevel of the cylindrical melon-shaped assembly (2) is perpendicular to the horizontal plane. The angle between the outer and inner bevels of the cylindrical melon-shaped assembly (2) is also α. The intersection of the outer and inner bevels is the vertex (11). Step 2: Weld the upper end cap (1), the cylindrical petal assembly (2) and the lower end cap (3), and make the circumferential welds with the apex (11) of the upper end cap (1) or the lower end cap (3) facing the apex (11) of the cylindrical petal assembly (2); Step 3: After welding is completed, the weld surface is ground and the completed weld is visually inspected, penetrant tested and radiographic tested.

2. The method for beveling the circumferential seam of a spherical container for nuclear power plants according to claim 1, characterized in that, Step 1 includes: Step 1-1: Place the upper head (1) and lower head (3) with their open ends facing down on the machine tool. Use the open ends of the upper head (1) and lower head (3) as a rough reference to level and align the workpiece. Turn the outer bevel (9) of the upper head (1) and lower head (3). The outer bevel (9) of the head is perpendicular to the horizontal plane. Step 1-2: Turn the inner bevel (10) of the upper head (1) and the lower head (3). The intersection of the outer bevel (9) and the inner bevel (10) is the vertex (11), and the included angle between the inner bevel (10) and the outer bevel (9) is α. Steps 1-3: Match the end diameters of the upper end cap (1) and the lower end cap (3) with the end diameter of the cylindrical melon-shaped assembly (2) to ensure that the upper end cap (1), the lower end cap (3) and the waist drum circle of the cylindrical melon-shaped assembly (2) are concentric and perpendicular. Steps 1-4: Place the cylindrical melon-shaped assembly (2) vertically on the machine tool, level and align the workpiece, and turn the inner bevel (7) of the upper and lower ends of the cylindrical melon-shaped assembly (2). The inner bevel (7) of the cylindrical melon-shaped assembly (2) is perpendicular to the horizontal plane. Steps 1-5: Turn the outer bevels (8) of the upper and lower ends of the cylinder petal assembly (2), and the included angle between the outer bevel (8) and the inner bevel (7) of the cylinder is α.

3. The method for beveling the circumferential seam of a spherical container for nuclear power plants according to claim 2, characterized in that: The inner bevel (10) of the upper head (1) or lower head (3) is machined at 1 / 3 of the thickness of the upper head (1) or lower head (3) from the outside to the inside.

4. The method for beveling the circumferential seam of a spherical container for nuclear power plants according to claim 2, characterized in that: The outer bevel (8) of the cylindrical melon-shaped assembly (2) is machined at 1 / 3 of the thickness of the cylindrical melon-shaped assembly (2) from the outside to the inside.

5. The method for beveling the circumferential seam of a spherical container for nuclear power plants according to claim 2, characterized in that: The included angle α is 120°.

6. The method for beveling the circumferential seam of a spherical container for nuclear power plants according to claim 2, characterized in that, Step 2 includes: Step 2-1: Set the upper end cap (1) on the lower side with the open end facing upward, and set the cylinder petal assembly (2) on the upper side, so that the straight line of the outer bevel (9) of the upper end cap (1) is parallel to the straight line of the inner bevel (7) of the cylinder petal assembly (2), and set the vertex (11) of the upper end cap (1) opposite to one vertex (11) of the cylinder petal assembly (2), while ensuring that the waistline of the upper end cap (1) and the waist drum circle of the cylinder petal assembly (2) are concentric and perpendicular. Then, spot weld and fix the cylinder outer bevel (8) of the cylinder petal assembly (2) and the outer bevel (9) of the upper end cap (1). Step 2-2: Use shielded metal arc welding to perform spot welding and fill welding in the inner bevel (7) of the cylinder of the cylinder lobe assembly (2) and the inner bevel (10) of the upper end cap (1) until the bevel is fully welded. The welding position is the flat welding position. Steps 2-3: Flip the welded upper end cap (1) and the cylindrical melon-shaped assembly (2), and place the lower end cap (3) on the lower side. Align the straight line of the outer bevel (9) of the lower end cap (3) with the straight line of the inner bevel (7) of the cylindrical melon-shaped assembly (2), and make the vertex (11) of the lower end cap (3) opposite to the other vertex (11) of the cylindrical melon-shaped assembly (2). At the same time, ensure that the lower end cap (3) and the waistline of the waist drum of the cylindrical melon-shaped assembly (2) are concentric and perpendicular, within the cylindrical melon-shaped assembly (2). The side bevel (7) and the inner bevel (10) of the lower head (3) are spot welded and filled by shielded metal arc welding until the bevel is full. The welding position is a flat welding position. At the same time, a special stainless steel grinding tool is used to clean the outer side of the weld between the outer bevel (8) of the cylinder and the outer bevel (9) of the head to clean the root weld of the upper head (1) and the cylinder petal assembly (2). After the root weld is cleaned, the root cleaning inspection tool (5) is used to check the size of the outer bevel after root cleaning so that the root cleaning inspection tool (5) can be completely placed in the outer bevel. Steps 2-4: Use shielded metal arc welding to perform spot welding and fill welding on the outer bevel (9) of the upper head (1) and the outer bevel (8) of the cylinder and the melon-shaped assembly (2) until the bevel is fully welded. The welding position is the flat welding position. Steps 2-5: Turn over the upper head (1), the cylinder petal assembly (2) and the lower head (3) that have been welded together. Use a stainless steel special grinding tool to clean the outer side of the weld between the lower head (3) and the cylinder petal assembly (2) from the space between the outer bevel (8) of the cylinder and the outer bevel (9) of the head. After removing the root weld, use a root cleaning inspection tool (5) to check the outer bevel size after root cleaning, so that the root cleaning inspection tool (5) can be completely placed in the outer bevel. Steps 2-6: Use shielded metal arc welding to perform spot welding and fill welding on the outer bevel (9) of the lower end cap (3) and the outer bevel (8) of the cylinder lobe assembly (2) until the bevel is fully welded. The welding position is the flat welding position.

7. The method for beveling the circumferential seam of a spherical container for nuclear power plants according to claim 6, characterized in that: The vertex (11) of the upper end cap (1) or the lower end cap (3) is opposite to the vertex (11) of the cylindrical melon-shaped assembly (2), and the distance between the vertex (11) of the upper end cap (1) or the lower end cap (3) and the vertex (11) of the cylindrical melon-shaped assembly (2) is 2-3 mm.

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