Nuclear power gas collection header dense connection pipe welding anti-deformation device and welding method

Abstract

The invention discloses a nuclear power gas collection header dense connecting pipe welding anti-deformation device, which comprises an anti-deformation ring, a door-shaped bracket and a connecting pipe connecting cover, and is characterized in that the anti-deformation ring is fixed on a box body of which the box bottom and a bottom rib plate are welded and is used for supporting the door-shaped bracket; the door-shaped supports correspond to the connecting pipes one to one, the door-shaped supports are all fixed to the anti-deformation ring, one ends of the connecting pipe connecting covers are fixed to the door-shaped supports, and the other ends of the connecting pipe connecting covers are fixedly connected with the connecting pipes. According to the device disclosed by the invention, good connecting pipe welding reversible deformation stress can be provided, and thermal shrinkage stress on a welding seam of the connecting pipe and the barrel can be directly counteracted.

Description

Technical Field

[0001] This invention relates to a welding deformation prevention device for densely arranged pipes in a nuclear power plant gas gathering header, specifically to a welding deformation prevention device and welding method for densely arranged pipes in a gas gathering header inside a nuclear power high-temperature gas-cooled reactor steam generator, belonging to the field of welding technology. Background Technology

[0002] The high-temperature gas-cooled reactor is currently one of the most advanced fourth-generation nuclear power technologies in the world. The steam generator is an important heat exchange device in the unit. During operation, it uses helium as a heat transfer medium to circulate heat in the nuclear reactor. A large fan is installed at the top of the equipment to circulate the gas. Helium is collected and transported to the fan through the gas collection header and fourteen gas pipes.

[0003] The gas collecting manifold plays a crucial role in helium collection and distribution. It is primarily constructed from fourteen connecting pipes, a housing, a bottom, a cover, and bottom stiffeners, all welded together. The connecting pipes are sealed to the external gas pipeline via flanges. To ensure the accuracy of each connecting pipe connection, strict requirements are placed on the angles of all connecting pipes and the distance from the flange end face to the manifold center. Angle deviations must be controlled within 0.5°, and the distance L from the connecting pipe flange to the manifold center must be controlled within 2mm. Designed to ensure the strength of the welded components during high-temperature operation, the welds between the connecting pipes and the housing are located on the inner side and require beveling and filling welding. Structurally, the cover cannot be installed before the connecting pipes are welded. The installation sequence of the gas collecting manifold components is as follows: First, weld the bottom to the housing and weld the bottom stiffeners on the inner side of the housing; then, machine the connecting pipe mounting holes on the housing and weld the inner beveles, installing and welding the fourteen connecting pipes; finally, install the cover to the housing and weld the outer side to complete the manifold manufacturing. After the box body is installed and welded to the bottom and bottom stiffeners, the lower side of the box body has good rigidity. However, the diameter of the pipe holes is large, and the fourteen pipes are distributed on both sides of the box body with a tight spacing. After the pipe holes are machined, the minimum spacing between the holes in the box wall is only 38mm, which greatly reduces the strength of the box body itself. After the pipe welding bevel is fully filled, the surface is flush with the inner wall of the cylinder, and the amount of welding filler is large. Due to the characteristics of stainless steel, such as high coefficient of linear expansion, high resistivity, and low thermal conductivity, the slow cooling process during welding will cause the box body to shrink towards the bevel side, resulting in elliptical deformation and deviation of the pipe angle. Furthermore, as the width of the bevel filler gradually increases, the welding heat output of each layer also gradually increases, causing the welding area of ​​the pipe at the top of the box body to shrink inward, resulting in a smaller diameter. At the same time, it will also cause the distance from the pipe flange to the center to decrease, ultimately causing the gas manifold pipe to fail to connect properly with the gas duct, and misalignment at the connection between the box cover and the box body, making it impossible to install properly.

[0004] In summary, controlling the welding deformation of the gas manifold nozzle is quite difficult, and there is an urgent need for a device and control method to suppress the welding deformation and shrinkage of the gas manifold nozzle. Summary of the Invention

[0005] To overcome the above problems, the inventors conducted in-depth research and designed a deformation-resistant welding device for densely connected pipes of a nuclear power plant gas gathering manifold. The nuclear power plant gas gathering manifold includes a box body 52 with a pre-welded bottom 53 and bottom stiffeners 55, and pipes 51 and a cover 54 to be welded to the box body 52. ​​The deformation-resistant device comprises an anti-deformation ring 1, a portal-shaped bracket 2, and a pipe connection cover 3. The anti-deformation ring 1 is fixed on the box body 52 with the welded box bottom 53 and bottom stiffening plate 55, providing support for the gate-shaped bracket 2; There are multiple portal-shaped brackets 2, each corresponding to a connecting pipe 51. All portal-shaped brackets 2 are fixed on the anti-deformation ring 1. One end of the connecting pipe cover 3 is fixed on the portal-shaped bracket 2, and the other end is fixedly connected to the connecting pipe 51.

[0006] In a preferred embodiment, the anti-deformation device further includes a tensioning screw 4, which connects to multiple portal brackets 2 or pipe connection covers 3.

[0007] In a preferred embodiment, the anti-deformation ring 1 includes a circular ring plate 11 and a plurality of connecting seats 12 fixed on the circular ring plate 11. The annular plate 11 is installed on the side wall of the housing 52 near the upper end face, and the connecting seat 12 corresponds one-to-one with the connecting pipe 51 and is located above the connecting pipe 51 to be welded.

[0008] In a preferred embodiment, the gate-shaped bracket 2 includes a C-shaped gate plate 21 and a support seat 22 disposed on the gate plate 21, the support seat 22 being used to fix the pipe connection cover 3.

[0009] In a preferred embodiment, an arc-shaped pad 23 is provided at the lower end of the door-shaped plate 21, and the arc-shaped pad 23 has the same curvature as the outer diameter of the box body 52.

[0010] In a preferred embodiment, the pipe connection cover 3 is connected to the flange of the pipe 51.

[0011] This invention also provides a method for preventing deformation during welding of densely connected pipes in nuclear power plant gas gathering headers, using the aforementioned device for preventing deformation during welding of densely connected pipes in nuclear power plant gas gathering headers, and comprising the following steps: S1. Weld the bottom 53 and bottom stiffening plate 55 of the welding box onto the box body 52; S2. Install the anti-deformation ring 1 on the housing 52; S3. Place the connector 51 in a suitable position and perform circumferential spot welding at the root of the bevel of the connector 51 to fix it on the housing 52. S4. Install the pipe connection cover 3 on the pipe 51, install the gate-shaped bracket 2 on the anti-deformation ring 1, and fix the pipe connection cover 3 to the gate-shaped bracket 2. S5. Complete the welding between the connector 51 and the housing 52; S6. Weld the box cover 54 to the box body 52; S7. Remove the anti-deformation device.

[0012] In a preferred embodiment, S5 includes the following sub-steps: S51. Place the box with the end facing down and support it on the anti-deformation ring with the column. Adjust the height to allow multiple people to weld the pipes inside. S52. Weld the pipe to the first layer of the box body, and then pre-tighten the nut connecting the portal bracket and the connecting cover bolt. S53. For the second to fourth weld layers of the weld pipe, water is sprayed on the back of the weld on the outside of the box to cool it during the welding process.

[0013] In a preferred embodiment, in S51, two or four people are used to symmetrically weld the pipes, and the welding sequence of the pipes adopts an interval welding machine method.

[0014] In a preferred embodiment, in S53, cooling water is used for spray cooling, and the cooling water flow rate is not less than 4L / min. After each group of pipes is welded, the temperature drops to below 40°C before the next group of pipes is welded.

[0015] The beneficial effects of this invention include: 1. The device of this invention has a highly versatile structural design and can be applied to the deformation control of welded pipe structures on the cylinder wall; 2. The device of the present invention can provide good anti-deformation stress for the nozzle welding, and can directly offset the thermal shrinkage stress on the weld between the nozzle and the cylinder; 3. The device of the present invention has complete functions and significant effects. It achieves strict control over multiple dimensions such as the roundness of the cylinder, the angle of the nozzle and the extension length during the welding process of multiple densely arranged nozzles. Moreover, the welding deformation control of all nozzles can be completed in just one installation. 4. The device of this invention is designed on the outside of the box, providing ample space for welding the pipes inside the box, and enabling multiple people to weld simultaneously; 5. The welding method provided by this invention can achieve high-efficiency operation of welding by 2 to 4 people at the same time, and the thermal shrinkage and deformation of stainless steel materials are greatly reduced by water spraying for cooling. Attached Figure Description

[0016] Figure 1 A schematic diagram of a welding deformation prevention device for dense pipe connections in a nuclear power plant gas gathering header according to a preferred embodiment of the present invention is shown. Figure 2A schematic diagram showing the welding sequence of a nuclear power plant gas gathering header dense pipe welding anti-deformation device according to a preferred embodiment of the present invention is provided. Figure 3 A schematic diagram of the anti-deformation ring structure of the welding anti-deformation device for the dense pipe of the gas gathering manifold in a nuclear power plant according to a preferred embodiment of the present invention is shown. Figure 4 This diagram illustrates a portal frame structure for a welding deformation prevention device for dense pipe connections in a nuclear power plant gas gathering header, according to a preferred embodiment of the present invention. Figure 5 A schematic diagram of the connection cover structure of the welding anti-deformation device for the dense pipe of the gas gathering manifold in a nuclear power plant according to a preferred embodiment of the present invention is shown. Figure 6 A schematic diagram of a tension screw structure for a welding anti-deformation device for a dense pipe connection of a nuclear power plant gas gathering header according to a preferred embodiment of the present invention is shown. Figure 7 A three-dimensional structural diagram of the gas collecting manifold is shown; Figure 8 A front view schematic diagram of the gas collection manifold is shown; Figure 9 A schematic diagram of a welding method for an anti-deformation device for dense pipe welding of a nuclear power plant gas gathering header according to a preferred embodiment of the present invention is shown.

[0017] Explanation of icon numbers: 1-Anti-deformation ring; 2-Gate-shaped bracket; 3- Connector cover; 4-Tighten the lead screw; 5-Gas collection manifold; 11-Circular ring plate; 12-Connector; 21-Gate-shaped panel; 22-Support base; 23-Arc-shaped pad; 24-rib plate; 31-Cover plate; 32-Screw; 33-Orifice plate; 41-Threaded sleeve; 42-Left-hand pull rod; 43 - Right-hand pull rod; 51-Taking over; 52-Box; 53 - Bottom of the box; 54 - Box lid; 55 - Bottom stiffener. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.

[0019] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0020] The gas-collecting header 5 of the high-temperature gas-cooled reactor steam generator is made entirely of stainless steel, with an outer diameter of 2000±3mm and a thickness of 20mm. Fourteen connecting pipes 51 are required to be welded to the outer wall, with an included angle of 19±0.5° between each pipe. The distance L from the flange end face of the connecting pipe to the center of the header is 1530±2mm. The connecting pipes are symmetrically distributed on both sides of the header's centerline. Each connecting pipe is welded to the header seam in 6-7 layers and then fully filled. Figure 1 , Figure 7 , Figure 8 As shown, the gas collecting manifold of the high-temperature gas-cooled reactor steam generator also has a box body 52, a box bottom 53, a box cover 54 and a bottom stiffening plate 55. The box bottom 53 and the bottom stiffening plate 55 are first welded to the box body 52, then the pipe 51 is welded, and finally the box cover 54 is welded.

[0021] According to the present invention, a welding deformation prevention device for densely connected pipes of a nuclear power plant gas gathering header includes an anti-deformation ring 1, a portal frame 2, and a pipe connection cover 3, wherein... The anti-deformation ring 1 is fixed on the box body 52 with the welded box bottom 53 and bottom stiffening plate 55, providing support for the gate-shaped bracket 2 and preventing the gate-shaped bracket 2 from being directly fixed on the box body, which would cause damage to the box body. The portal frame 2 has multiple members, each corresponding to a connecting pipe 51. All portal frame 2 members are fixed on the anti-deformation ring 1. One end of the connecting pipe connecting cover 3 is fixed on the portal frame 2, and the other end is fixedly connected to the connecting pipe 51, so that the connecting pipe 51 is subjected to tensile force during the welding process to counteract the shrinkage stress of the weld between the connecting pipe and the box body.

[0022] Preferably, the device further includes a tensioning screw 4, which connects multiple portal brackets 2 or pipe connection caps 3, so that the pipe 51 is fixed as a whole during the welding process, thereby suppressing the displacement of the pipe angle.

[0023] In a preferred embodiment, the anti-deformation ring 1 includes a circular ring plate 11 and a plurality of connecting seats 12 fixed on the circular ring plate 11. After the bottom 53 and the bottom stiffener 55 are welded to the box body 52, the circular ring plate 11 is installed on the side wall of the box body 52 near the upper end face, such as... Figure 1 , Figure 3As shown, the connecting seat 12 corresponds one-to-one with the connecting pipe 51 and is located above the connecting pipe 51 to be welded, and is used to fix the gate-shaped bracket 2.

[0024] Preferably, the connecting seat 12 and the portal frame 2 are fixedly connected by bolts.

[0025] In a preferred embodiment, the portal frame 2 includes a C-shaped portal plate 21 and a support base 22 disposed on the portal plate 21, such as... Figure 4 As shown. The support base 22 is used to fix the pipe connection cover 3.

[0026] In a preferred embodiment, the support base 22 is a support base that is connected to the pipe connection cover 3 by a screw, which facilitates the adjustment of the fixed distance between the support base 22 and the pipe connection cover 3, thereby adjusting the preset tension in front of the pipe 51 to better counteract the shrinkage stress of the weld between the pipe and the box body.

[0027] In a preferred embodiment, the upper end of the gate-shaped plate 21 is provided with a threaded hole for connection with the connecting seat 12; An arc-shaped pad 23 is provided at the lower end of the door-shaped plate 21. The arc-shaped pad 23 has the same curvature as the outer diameter of the box body 52, which is used to increase the contact area between the door-shaped plate 21 and the box body 52 and avoid indentation on the outer wall of the box body when the door-shaped bracket is supported.

[0028] In a more preferred embodiment, a stiffening plate 24 is further provided between the arc-shaped pad 23 and the gate-shaped plate 21 to enhance its supporting strength.

[0029] In a preferred embodiment, the pipe connection cover 3 is connected to the flange of the pipe 51.

[0030] In a preferred embodiment, the connecting pipe cover 3 includes a cover plate 31 and a screw 32, the screw 32 being used to connect to the support base 22 of the portal plate, such as... Figure 5 As shown.

[0031] In a preferred embodiment, the pipe connection cover 3 includes perforated plates 33 disposed on both sides for connection with the tension screw 4, thereby fixing the distance between adjacent pipe connection covers 3.

[0032] In a preferred embodiment, the tensioning screw 4 includes a threaded sleeve 41, a left-hand pull rod 42, and a right-hand pull rod 43, wherein the left-hand pull rod 42 and the right-hand pull rod 43 are respectively threaded to both sides of the threaded sleeve 41, as shown below. Figure 6 As shown. More preferably, the threaded sleeve 41 has a square plane for rotational preload.

[0033] Preferably, the anti-deformation ring 1 is installed on the side wall of the housing 52 at a position 5-10 mm from the upper end face.

[0034] Preferably, the anti-deformation ring 1 is intermittently welded to the outer wall of the box in the circumferential direction, so that the anti-deformation ring can form a strong rigid fixation on the end of the box to prevent it from becoming elliptical and to prevent the welding from shrinking due to heat.

[0035] According to the present invention, before welding the gas collection manifold body 52 and the pipe 51, the anti-deformation ring 1 is installed at the end of the body to make it fit tightly against the outer wall of the body. The circumferential welding is intermittent. At this time, the anti-deformation ring can form a strong rigid fixation on the end of the body to prevent it from becoming elliptical and shrinking due to welding heat. The connecting cover 3 is installed on the flange at the end of each pipe 51 and pre-tightened by bolts and nuts. Then, the portal bracket 2 is straddled on the outside of each pipe and connected to the connecting seat 12 above the anti-deformation ring. The lower arc-shaped pad 23 is supported on the outer wall of the manifold. At the same time, the connecting cover screw 32 is inserted into the portal bracket support seat 22. The screw is pre-tightened with nuts to support the portal bracket on the outside of the body and the pipe is pulled outward from the body by the screw. Finally, the tension screw 4 is used to connect and pre-tighten the threaded sleeve 41 between each cover plate 31. At this time, the left-hand pull rod 42 and the right-hand pull rod 43 move inward at the same time to rigidly fix all the flange ends of the pipes. At this point, the roundness of the box end, the angle of the nozzle, and the extension length of the nozzle are all rigidly fixed and subjected to the reverse tension in the direction of welding shrinkage, which can offset a large amount of welding shrinkage stress during the welding process. During the welding process, a reasonable sequence of interval welding and layer welding is arranged according to the position of the nozzle, and water is sprayed on the back side of the weld to quickly cool it down, ensuring a good fit between the box and the box cover after welding and meeting the various dimensional requirements of the nozzle.

[0036] This invention also discloses a method for preventing deformation during welding of densely packed pipes in nuclear power plant gas gathering headers, which employs the aforementioned device for preventing deformation during welding of densely packed pipes in nuclear power plant gas gathering headers, and includes the following steps: S1. Weld the bottom 53 and bottom stiffening plate 55 of the welding box onto the box body 52; S2. Install the anti-deformation ring 1 on the housing 52; S3. Place the connector 51 in a suitable position and perform circumferential spot welding at the root of the bevel of the connector 51 to fix it on the housing 52. S4. Install the pipe connection cover 3 on the pipe 51, install the gate-shaped bracket 2 on the anti-deformation ring 1, and fix the pipe connection cover 3 to the gate-shaped bracket 2. S5. Complete the welding between the connector 51 and the housing 52; S6. Weld the box cover 54 to the box body 52; S7. Remove the anti-deformation device.

[0037] Preferably, in S2, an anti-deformation ring 1 is installed 5-10mm below the upper end face of the box body, and is intermittently welded to the outer wall of the box body in the circumferential direction.

[0038] Preferably, in step S3, 3 to 4 circumferential spot welds are used for fixation at the root of the bevel.

[0039] Preferably, in S4, a connecting cover 3 is installed on the end face of each pipe flange and pre-tightened to it with bolts and nuts, at which time the two bolts of the connecting cover are in a horizontal position; Next, install the portal brackets 2 one by one on the outside of the pipe, aligning the holes of the support seats 22 on both sides of the portal plate with the connecting cover screws 32 and inserting them. The upper hole of the portal plate is connected to the anti-deformation ring connecting seat 12 by a pin. The lower side is made to fit the arc-shaped pad 23 against the outer wall of the bottom of the box. Then, the portal brackets are tightened with pre-tightening nuts to apply a pulling force outward along their axis to the pipe. At this time, the upper and lower ends of the portal brackets form a strong rigid support with the box.

[0040] Preferably, in S4, the adjacent pipe connecting cover 3 or the gate-shaped bracket 2 is also connected by a tension screw 4.

[0041] At this time, the end of the box is like Figure 2 The anti-deformation ring 1, as shown, maintains good roundness and is rigidly fixed to the anti-deformation ring by intermittent welding in the circumferential direction. The weld seam of the connecting pipe is subjected to the pre-tightening force of the portal frame 2 on the connecting pipe cover 3, which can offset a large amount of welding shrinkage stress during welding. The circumferential angle deviation caused by welding shrinkage in the connecting pipe is well controlled by the fixing of the tension screw 4. Through the control of the above-mentioned device of the present invention, a large amount of welding deformation can be effectively controlled.

[0042] Because the dimensional tolerances of the components in the nuclear power plant gas gathering header are stringent, shrinkage stress generated during welding still exists around the weld. After the device is dismantled following welding, a small amount of elastic deformation can still occur, easily leading to dimensional deviations. In this invention, preferably, S5 includes the following sub-steps: S51. Place the box with the end facing down and support it on the anti-deformation ring with the column. Adjust the height to allow multiple people to weld the pipes inside. S52. Weld the pipe to the first layer of the box body, and then pre-tighten the nut connecting the portal bracket and the connecting cover screw to prevent elastic shrinkage later. S53. For the second to fourth weld layers of the weld pipe, water is sprayed on the back of the weld on the outside of the box to cool it during the welding process.

[0043] Preferably, in S51, such as Figure 9 As shown, two or four people are used for symmetrical welding of the connectors. The welding sequence of the connectors adopts an interval welding method, and more preferably, the interval welding sequence is as follows: Figure 2 As shown, it can control the heat output distance on both sides to avoid heat concentration and deformation, while improving manufacturing efficiency.

[0044] Preferably, in S52, the preload force is not less than 200 Nm, and the distance from the end face of the flange to the center is measured to 1530~1531 mm for anti-deformation control to obtain the best control effect.

[0045] Preferably, in step S53, cooling water, preferably deionized water, is used for water spray cooling to accelerate the cooling rate of the weld and reduce deformation and shrinkage. More preferably, the cooling water flow rate is not less than 4 L / min, and the next group of welds is carried out only after the temperature of each group of pipes has dropped below 40°C.

[0046] Preferably, in step S53, welding is performed in an alternating welding sequence. After all the pipes are welded, the 5th to 7th layers of each group of pipes are welded again using the above method to complete all pipe welding. At this time, the pipes are rigidly fixed by the device and the anti-deformation tension can effectively balance the weld shrinkage stress. Furthermore, the rapid cooling by spraying water on the back side of the weld during the welding process can effectively shorten the cooling rate, thereby further controlling thermal shrinkage deformation and reducing the diameter of the box.

[0047] In step S6, the box is flipped over so that the port faces upwards. Due to the large amount of welding on the box, there is still welding shrinkage stress in the box. Therefore, before removing the anti-deformation device, the box cover 54 is installed on the upper end of the box 52. At this time, the end of the box is supported by the anti-deformation ring to maintain good roundness. After the first layer of welding is performed with the box cover, the gas collection box structure is formed. At this time, the box cover replaces the anti-deformation ring to provide good support for the box. Then, the parts of the anti-deformation device can be removed one by one.

[0048] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] The present invention has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present invention based on these embodiments, all of which fall within the scope of protection of the present invention.

Claims

1. A welding deformation prevention device for dense pipes of a nuclear power plant gas gathering header, the nuclear power plant gas gathering header comprising a box body (52) with a welded bottom (53) and bottom stiffeners (55), and pipes (51) and a box cover (54) to be welded onto the box body (52), characterized in that, The anti-deformation device includes an anti-deformation ring (1), a portal frame (2), and a pipe connection cover (3), wherein... The anti-deformation ring (1) is fixed on the box body (52) with the welded box bottom (53) and bottom stiffener (55) to provide support for the gate-shaped bracket (2); The gate-shaped bracket (2) has multiple units, each corresponding to a connecting pipe (51). All the gate-shaped brackets (2) are fixed on the anti-deformation ring (1). One end of the connecting pipe connecting cover (3) is fixed on the gate-shaped bracket (2), and the other end is fixedly connected to the connecting pipe (51).

2. The nuclear power plant gas gathering header dense pipe welding anti-deformation device according to claim 1, characterized in that, The anti-deformation device also includes a tension screw (4) and connects multiple portal brackets (2) or pipe connection caps (3).

3. The nuclear power plant gas gathering header dense pipe welding anti-deformation device according to claim 1, characterized in that, The anti-deformation ring (1) includes a circular ring plate (11) and multiple connecting seats (12) fixed on the circular ring plate (11). The annular plate (11) is installed on the side wall of the box (52) near the upper end face. The connecting seat (12) corresponds one-to-one with the pipe (51) and is located above the pipe (51) to be welded.

4. The nuclear power plant gas gathering header dense pipe welding anti-deformation device according to claim 1, characterized in that, The gate-shaped bracket (2) includes a C-shaped gate plate (21) and a support seat (22) disposed on the gate plate (21), the support seat (22) being used to fix the pipe connection cover (3).

5. The nuclear power plant gas gathering header dense pipe welding anti-deformation device according to claim 4, characterized in that, The lower end of the door-shaped plate (21) is provided with an arc-shaped pad (23), which has the same curvature as the outer diameter of the box body (52).

6. The nuclear power plant gas gathering header dense pipe welding anti-deformation device according to claim 1, characterized in that, The connector connecting cover (3) is connected to the flange of the connector (51).

7. A method for preventing deformation during welding of dense connecting pipes in nuclear power plant gas gathering headers, comprising using the deformation-preventing device for welding dense connecting pipes in nuclear power plant gas gathering headers as described in any one of claims 1-6, characterized in that... Includes the following steps: S1. Weld the bottom and bottom stiffening plates of the box to the box body; S2. Install the anti-deformation ring on the housing; S3. Place the connector in a suitable position and perform circumferential spot welding at the root of the connector bevel to fix it to the box body; S4. Install the pipe connection cover on the pipe, install the gate-shaped bracket on the anti-deformation ring, and fix the pipe connection cover to the gate-shaped bracket. S5. Complete the welding between the connector and the housing; S6. Weld the lid to the box body; S7. Remove the anti-deformation device.

8. The method for preventing deformation during welding of dense pipes in nuclear power plant gas gathering headers according to claim 1, characterized in that, S5 includes the following sub-steps: S51. Place the box with the end facing down and support it on the anti-deformation ring with the column. Adjust the height to allow multiple people to weld the pipes inside. S52. Weld the pipe to the first layer of the box body, and then pre-tighten the nut connecting the portal bracket and the connecting cover bolt. S53. For the second to fourth weld layers of the weld pipe, water is sprayed on the back of the weld on the outside of the box to cool it during the welding process.

9. The method for preventing deformation during welding of densely connected pipes in nuclear power plant gas gathering headers according to claim 8, characterized in that, In S51, two or four people are used to symmetrically weld the pipes, and the welding sequence of the pipes adopts the interval welding machine method.

10. The method for preventing deformation during welding of densely connected pipes in nuclear power plant gas gathering headers according to claim 8, characterized in that, In S53, cooling water is used for spray cooling, with a flow rate of not less than 4L / min. After each group of pipes is welded, the temperature drops to below 40℃ before the next group of welds is carried out.

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