Construction method for secondary cutting of on-site installation of steel lining gate sleeve of nuclear power plant building

Abstract

This invention discloses a secondary cutting construction method for on-site installation of gate sleeves for steel linings in nuclear power plant buildings, relating to the field of nuclear power plant construction technology. The secondary cutting area is divided into multiple construction sections along the circumference. After each section is cut, the bevel is immediately ground and the sections are assembled and welded. This method releases and constrains cutting and welding stress section by section, avoiding stress concentration and deformation accumulation caused by continuous construction around the entire circumference. It ensures that the reinforcing ring plate and the steel lining wall panel maintain a tight fit throughout the entire circumference, thus reliably guaranteeing the sealing performance and structural safety of the connection between the gate sleeve and the steel lining. This method solves the defects of existing single-cut opening methods, where structural deformation and measurement errors lead to ineffective fitting of the reinforcing ring plate and difficulties in welding assembly.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant construction technology, and in particular to a secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings. Background Technology

[0002] The steel liner of a nuclear power plant is a crucial structure ensuring the sealing integrity of the containment vessel. Gate sleeves, as key access components for personnel and equipment, directly impact the containment's sealing performance and overall structural safety. With the continuous expansion of nuclear power plant construction and the constant improvement of design standards, increasingly stringent requirements have been placed on the installation precision and welding quality of steel-lined gate sleeves. To meet these requirements, the industry has gradually developed a construction process involving on-site cutting and drilling into the steel liner panels, followed by welding the gate sleeves. This cutting and installation method is continuously explored and optimized in engineering practice.

[0003] Currently, the common practice for on-site installation of steel-lined gate sleeves in nuclear power plant buildings is as follows: according to the design drawings, the corresponding installation holes are cut at the preset positions of the steel lining wall panels in one go according to the design dimensions of the gate sleeve reinforcing ring plate. Then, the gate sleeve is hoisted into place, the reinforcing ring plate is assembled with the wall panel, and finally, beveling is performed along the entire circumference to complete the sleeve installation.

[0004] However, when constructing gate sleeves on the steel lining wall panels of the nuclear island plant using existing technology, it is extremely difficult to cut them precisely to the dimensions shown in the drawings in one go, as the steel lining wall panels are large on-site structures and are affected by factors such as the construction environment, measurement errors, and structural deformation. If there is any deviation in the size or position of the opening, the reinforcing ring plate and the wall panel will not be able to fit effectively, making welding assembly difficult and seriously affecting the sealing performance and structural safety. Summary of the Invention

[0005] The main objective of this invention is to propose a secondary cutting construction method for on-site installation of gate sleeves for steel lining in nuclear power plant buildings. This method aims to solve the technical problems encountered in the existing technology when constructing gate sleeves on steel lining wall panels of nuclear island buildings. Due to the large on-site structure of the steel lining wall panels, the difficulty of accurately cutting them to the dimensions shown in the drawings in one go is extremely high, as the steel lining wall panels are large structures affected by factors such as the construction environment, measurement errors, and structural deformation. If the opening size or position deviates, it will lead to the inability of the reinforcing ring plate to effectively fit with the wall panel, making welding assembly difficult and seriously affecting the sealing performance and structural safety.

[0006] To achieve the above objectives, in a first aspect, the present invention proposes a secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings, comprising the following steps: A first cut is made at the preset installation position on the steel lining wall panel to form a reserved hole; wherein, the gate sleeve is installed at the preset installation position, and the diameter or outline size of the reserved hole is at least 50mm smaller than the corresponding size of the outer edge of the reinforcing ring plate; The gate sleeve is hoisted to the preset position and passed through the reserved hole; Adjust the position of the gate sleeve so that the reinforcing ring plate is in contact with the steel lining wall plate, and the cross center line of the reinforcing ring plate coincides with the cross center line of the steel lining wall plate; Using the outer edge of the reinforcing ring plate as the on-site cutting reference, the steel lining wall panel is cut a second time, with a 2-3mm bevel machining allowance reserved; The secondary cutting area is divided into multiple construction sections along the circumference and implemented section by section. After each section of secondary cutting is completed, the corresponding section is beveled and welded together until the full circumference connection construction is completed.

[0007] The technical solution of the present invention involves first making a first cut at the preset installation position of the steel lining wall panel to form a reserved hole with a diameter or hole outline size at least 50mm smaller than the corresponding size of the outer edge of the reinforcing ring plate. Then, the gate sleeve is hoisted through the reserved hole and adjusted so that the reinforcing ring plate and the wall panel are in close contact and the cross center line coincides. Subsequently, a second cut is made with the outer edge of the reinforcing ring plate as the on-site cutting reference, with a 2-3mm beveling allowance reserved. Finally, the cutting, beveling, and assembly welding are completed segment by segment along the circumference. During construction, the pre-drilled holes formed during the first cut are significantly smaller than the outer edge of the reinforcing ring plate. This allows for sufficient compensation margins in both the circumferential and radial directions after the reinforcing ring plate is in place. This effectively absorbs positional deviations caused by on-site installation deformation and measurement errors in the steel lining wall panel, ensuring a tight fit between the reinforcing ring plate and the wall panel after adjustment, with the cross center lines accurately aligned. Based on this, instead of relying on theoretical dimensions, the outer edge of the already fitted reinforcing ring plate is used directly as the on-site reference for the second cut. This eliminates problems such as misaligned openings and mismatched contours caused by deformation of the large steel lining wall panel structure itself and measurement deviations. It achieves precise matching between the opening contour and the outer edge of the reinforcing ring plate, ensuring a uniform gap between the reinforcing ring plate and the wall panel assembly, thus creating a prerequisite for obtaining a high-quality welded joint. The 2-3mm beveling allowance is removed by grinding, resulting in a weld beveling with uniform angles and blunt edges throughout the circumference, improving the uniformity of weld deposition. The secondary cutting area is divided into multiple construction sections along the circumference. After each section is cut, the bevel is immediately ground and the sections are assembled and welded. This allows for the release and constraint of cutting and welding stress section by section, avoiding stress concentration and deformation accumulation caused by continuous construction around the entire circumference. This ensures that the reinforcing ring plate and the steel lining wall plate maintain a tight fit throughout the entire circumference, thus reliably guaranteeing the sealing performance and structural safety of the connection between the gate sleeve and the steel lining. This solves the defects of the existing single-cut opening method, which results in the reinforcing ring plate not fitting effectively and welding assembly being difficult due to structural deformation and measurement errors. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0009] Figure 1 The flowchart illustrates the secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings, as provided by this invention.

[0010] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0012] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0013] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0014] This invention proposes a secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings.

[0015] Please see Figure 1 To facilitate understanding, this method for secondary cutting of steel-lined gate sleeves in nuclear power plant buildings during on-site installation includes the following steps: S100. Make a first cut at the preset installation position on the steel lining wall panel to form a reserved hole; wherein, the gate sleeve is installed at the preset installation position, and the diameter or outline size of the reserved hole is at least 50mm smaller than the corresponding size of the outer edge of the reinforcing ring plate.

[0016] Specifically, before the formal cutting operation, the construction personnel first determined the preset installation position of the gate sleeve on the steel lining wall panel based on the reviewed and confirmed construction drawings and on-site measurement data, and marked the center line of the cross on the surface of the wall panel as the reference line for subsequent processes.

[0017] After completing the benchmark markings, the steel lining wall panel is cut for the first time to form the reserved holes. It should be noted that the reserved holes formed in this step are not cut into shape in one go according to the actual outer edge size of the gate sleeve reinforcing ring plate. Instead, the diameter or outline size of the reserved holes is intentionally controlled to be at least 50mm smaller than the corresponding outer edge size of the reinforcing ring plate.

[0018] Steel-lined wall panels are large-scale on-site structures in complex construction environments. They are affected by a combination of factors, including measurement errors, operational deviations, and structural deformation due to weight. Directly cutting the reinforcing ring plate to its outer edge dimensions in a single, precise cut can easily lead to deviations in the opening position or size. If these deviations exceed allowable limits, the reinforcing ring plate will not fit effectively with the wall panel, causing difficulties in subsequent welding and assembly. In severe cases, repair welding may be necessary, resulting in significant project costs. Therefore, by leaving a margin of at least 50mm during the initial cut, ensuring the pre-drilled hole is significantly smaller than the outer edge of the reinforcing ring plate, it is possible to guarantee that the reinforcing ring plate reliably covers the wall panel surface after the gate sleeve is hoisted into place. This provides the basis for a second, precise cut using the outer edge of the reinforcing ring plate as a reference, fundamentally eliminating the risk of installation failure due to deviations in the initial cut and significantly improving construction reliability and safety.

[0019] S200. Hoist the gate sleeve to the preset position and make the sleeve pass through the reserved hole.

[0020] Specifically, the gate sleeve is hoisted to the pre-set installation position corresponding to the steel lining wall panel using lifting equipment. During the hoisting process, hoisting equipment and lifting tools should be reasonably selected according to the weight, dimensions, and on-site construction space conditions of the gate sleeve, and a special hoisting plan should be formulated to ensure that the hoisting operation is safe and under control.

[0021] During the hoisting and positioning process, construction personnel need to guide the gate sleeve to move slowly along a direction perpendicular to the steel lining wall panel, so that the sleeve body passes through the reserved hole from the outside of the wall panel until the reinforcing ring plate abuts against the outer surface of the wall panel, at which point the hoisting and movement stops. Since the reserved hole size has been made with sufficient allowance according to the requirements of S100, the sleeve body can pass through the reserved hole smoothly without interfering with the cut edge of the wall panel.

[0022] It should be noted that appropriate measures should be taken to temporarily restrain the gate sleeve during the hoisting process to prevent the sleeve from shifting or tilting under the influence of gravity and construction disturbance, so as to facilitate the smooth progress of subsequent adjustment procedures.

[0023] S300. Adjust the position of the gate sleeve so that the reinforcing ring plate is in contact with the steel lining wall plate, and make the cross center line of the reinforcing ring plate coincide with the cross center line of the steel lining wall plate.

[0024] Specifically, after the gate sleeve is perforated and positioned, the construction workers use the fine-tuning operation of the lifting equipment and manual auxiliary tools to make precise adjustments to the planar position and spatial posture of the gate sleeve.

[0025] The adjustment work is divided into two levels: First, in terms of planar position, the cross center lines pre-marked on the reinforcing ring plate and the cross center lines marked on the steel lining wall plate are compared and checked using precision measuring instruments such as a total station or laser plumb liner. The deviations in the horizontal and vertical directions are gradually eliminated until the two sets of cross center lines completely coincide, ensuring that the installation axis of the gate sleeve matches the design axis. Second, in terms of spatial posture, the verticality or tilt angle of the gate sleeve is detected using tools such as a level and plumb bob, and adjustments are made according to the detection results to ensure that the sleeve axis direction meets the design requirements.

[0026] After the position is adjusted, the construction personnel should slowly move the sleeve to ensure that the surface of the reinforcing ring plate is fully in contact with the outer surface of the steel lining wall panel. There should be no obvious gaps or warping between the contact surfaces. After confirming the fit, the gate sleeve should be temporarily fixed immediately using temporary spot welding or wedge clamps to prevent the sleeve from shifting during subsequent operations, thus ensuring the accuracy of the secondary cutting and assembly welding processes.

[0027] S400. Using the outer edge of the reinforcing ring plate as the on-site cutting reference, the steel lining wall panel is cut a second time, with a 2-3mm beveling allowance reserved.

[0028] Specifically, using the actual outer edge of the gate sleeve reinforcing ring plate, which has been temporarily fixed in place, as a reference, the cutting outline is directly marked on the steel lining wall plate, and then the wall plate is cut a second time.

[0029] It is important to note that the method of selecting the cutting reference in this step is one of the core technical points of this application. Unlike the existing technology that determines the cutting profile based on the theoretical dimensions of drawings, this application directly uses the outer edge of the reinforcing ring plate actually in place on site as the cutting reference. This means that the cutting profile is determined entirely by following the actual installation position of the gate sleeve, rather than relying on the conversion and transmission of measurement data. By adopting this method, the cumulative errors of intermediate links such as measurement errors and layout deviations can be minimized, so that the fit clearance between the wall panel opening profile formed by the second cut and the outer edge of the reinforcing ring plate reaches the optimal state, providing a reliable guarantee for the high-quality implementation of subsequent beveling and welding operations.

[0030] When performing the second cut, the cutting line should be close to the outer edge of the reinforcing ring plate, but without damaging the reinforcing ring plate itself, and a 2-3mm beveling allowance should be reserved. The purpose of reserving this allowance is to provide sufficient processing space for subsequent beveling and grinding, ensuring that the beveling geometry and dimensional accuracy meet the requirements of the welding process specifications, and avoiding the impact on weld fusion quality due to insufficient beveling size caused by cutting errors.

[0031] The second cut can also be carried out using plasma cutting or gas cutting. During the cutting process, the cutting speed should be kept uniform and the cutting nozzle should be kept perpendicular to the wall panel to ensure the flatness and perpendicularity of the cut surface and reduce the amount of subsequent grinding work.

[0032] S500: Divide the secondary cutting area into multiple construction sections along the circumference and implement them one by one. After each secondary cutting is completed, the corresponding section is beveled and welded until the full circumference connection construction is completed.

[0033] Specifically, instead of completing the second round of cutting around the entire circumference before welding, the area of ​​the second round of cutting around the circumference is divided into several construction sections along the circumference. Each construction section is then carried out in sequence through a cyclical process of "cutting - grinding - assembly and welding" until the entire circumference connection between the gate sleeve and the steel lining wall panel is completed.

[0034] It is important to note that the construction sequence of cutting and welding in sections rather than cutting the entire circumference all at once is of significant engineering importance. If the entire circumference is cut first and then welded, the constraint effect of the steel lining panel on the gate sleeve will be significantly weakened after the entire circumference is cut. The gate sleeve is prone to displacement and attitude deviation under its own weight and construction disturbances, resulting in the loss of the already adjusted installation accuracy and causing difficulties in subsequent assembly and welding. However, by adopting the method of cutting in sections and then welding immediately after each section is cut, the welded sections provide continuous and effective constraint on the gate sleeve, thereby maintaining the positional stability of the gate sleeve throughout the entire construction process and ensuring the consistency of the installation accuracy throughout the entire circumference.

[0035] During the beveling process, the cut surface should be machined into a bevel shape that meets the specified angle and blunt edge dimensions according to the welding procedure requirements. Single-sided or double-sided bevels are typically used, with the specific form determined based on the wall plate thickness and welding operability. After grinding, the bevel and a certain area on both sides should be cleaned to remove oxide layers, oil, and moisture, ensuring the welding environment meets the process requirements.

[0036] During the assembly welding process, welding should be carried out in accordance with the approved welding procedure to ensure that the weld has a good appearance and that the internal quality meets the acceptance requirements of the relevant standards for nuclear power plants, so as to ensure the sealing integrity and structural safety of the containment steel lining.

[0037] In this embodiment, a first cut is made at the preset installation position of the steel lining wall panel to form a reserved hole with a diameter or hole outline size at least 50mm smaller than the corresponding size of the outer edge of the reinforcing ring plate. Then, the gate sleeve is hoisted through the reserved hole and adjusted so that the reinforcing ring plate and the wall panel are in close contact and the cross center line coincides. Subsequently, a second cut is made with the outer edge of the reinforcing ring plate as the on-site cutting reference and a 2-3mm beveling allowance is reserved. Finally, the cutting, beveling, and assembly welding are completed segment by segment along the circumference. During construction, the pre-drilled holes formed during the first cut are significantly smaller than the outer edge of the reinforcing ring plate. This allows for sufficient compensation margins in both the circumferential and radial directions after the reinforcing ring plate is in place. This effectively absorbs positional deviations caused by on-site installation deformation and measurement errors in the steel lining wall panel, ensuring a tight fit between the reinforcing ring plate and the wall panel after adjustment, with the cross center lines accurately aligned. Based on this, instead of relying on theoretical dimensions, the outer edge of the already fitted reinforcing ring plate is used directly as the on-site reference for the second cut. This eliminates problems such as misaligned openings and mismatched contours caused by deformation of the large steel lining wall panel structure itself and measurement deviations. It achieves precise matching between the opening contour and the outer edge of the reinforcing ring plate, ensuring a uniform gap between the reinforcing ring plate and the wall panel assembly, thus creating a prerequisite for obtaining a high-quality welded joint. The 2-3mm beveling allowance is removed by grinding, resulting in a weld beveling with uniform angles and blunt edges throughout the circumference, improving the uniformity of weld deposition. The secondary cutting area is divided into multiple construction sections along the circumference. After each section is cut, the bevel is immediately ground and the sections are assembled and welded. This allows for the release and constraint of cutting and welding stress section by section, avoiding stress concentration and deformation accumulation caused by continuous construction around the entire circumference. This ensures that the reinforcing ring plate and the steel lining wall plate maintain a tight fit throughout the entire circumference, thus reliably guaranteeing the sealing performance and structural safety of the connection between the gate sleeve and the steel lining. This solves the defects of the existing single-cut opening method, which results in the reinforcing ring plate not fitting effectively and welding assembly being difficult due to structural deformation and measurement errors.

[0038] In one embodiment, step S100 includes: S110. Based on the design drawings and on-site measurement results, mark the installation center line of the gate sleeve on the steel lining wall panel.

[0039] Specifically, before carrying out the first cutting operation, the construction personnel first need to determine the installation center line of the gate sleeve on the surface of the steel lining wall panel based on the reviewed and confirmed construction drawings and the actual on-site measurement data.

[0040] When calibrating the installation centerline, the theoretical coordinates given in the design drawings and the actual measured condition of the wall panels on site should be considered comprehensively. These two coordinates should be cross-checked to eliminate positional deviations caused by factors such as wall panel manufacturing errors, installation deviations, and structural weight deformation. Specifically, a total station can be used to convert the theoretical coordinates on the drawings into actual measured coordinates on site. Perpendicular crosshairs should then be marked on the wall panel surface, and permanent markings should be made using a steel needle or a special marker pen to ensure that subsequent processes can be reliably implemented based on this centerline.

[0041] S120. Determine the first cutting hole position based on the installation center line.

[0042] Specifically, after the installation centerline is marked and verified, the hole contour for the first cut is determined based on the centerline and the predetermined geometric relationship.

[0043] The diameter or outline of the pre-drilled hole formed by the first cut must be at least 50mm smaller than the corresponding dimension of the outer edge of the reinforcing ring plate. Therefore, when determining the cutting hole position based on the installation centerline, the cutting allowance should be reduced by at least 50mm in all directions around the centerline as the axis of symmetry to determine the actual outline of the first cut. This outline should then be clearly marked on the wall panel surface with a stone pencil or scriber as the direct basis for the cutting operation. By determining the hole position by reducing the cutting allowance inward based on the installation centerline, it can be ensured that the pre-drilled hole formed by the first cut is consistent with the designed installation position of the gate sleeve in terms of geometric center, providing reasonable operating space for subsequent position adjustments after the sleeve is perforated and installed.

[0044] S130. Cut the steel lining wall panel according to the predetermined contour to form the initial hole.

[0045] Specifically, after completing the marking of the cutting hole outline, the steel lining wall panel is cut according to the marked predetermined outline to form the initial hole.

[0046] When choosing a cutting method, conventional on-site thermal cutting methods such as plasma arc cutting or oxy-acetylene cutting can be selected based on the material and thickness of the panel and the on-site construction conditions. Among them, plasma arc cutting has the characteristics of narrow kerf, small heat-affected zone, and relatively flat cutting surface. For cases with thicker panels, its cutting efficiency and cutting quality are superior to gas cutting. Therefore, when conditions permit, plasma arc cutting is the preferred method.

[0047] During the cutting operation, the operator should advance the cutting torch evenly and continuously along the predetermined contour line, keeping the torch perpendicular to the wall panel surface. The cutting speed should match the rated parameters of the cutting equipment used to avoid uneven cut surfaces due to excessive cutting speed or overheating of the cut surface due to excessive cutting speed, which would affect subsequent processing. The cutting path should start from the inside of the marked contour line and must not exceed the predetermined contour to ensure that the initial hole size does not exceed the predetermined range, leaving sufficient margin for subsequent edge cleaning.

[0048] The specific shape of the pre-drilled hole formed by the first cut should be adapted to the cross-sectional shape of the gate sleeve body. The hole diameter or hole outline size should meet the aforementioned requirement of being at least 50mm smaller than the corresponding size of the outer edge of the reinforcing ring plate, so as to ensure sufficient compensation margin in both the circumferential and radial directions after the reinforcing ring plate is in place. The cutting can be carried out by plasma cutting or gas cutting. After cutting, the edges should be trimmed to remove burrs and spatter to ensure smooth sleeve insertion.

[0049] S140. Clean the burrs, spatter, and oxide layer from the edge of the initial hole to obtain the reserved hole.

[0050] Specifically, after the initial hole is cut, the cut edges of the initial hole need to be thoroughly cleaned to remove burrs, metal spatter, and oxide layers formed on the surface of the heat-affected zone generated during the cutting process, so as to obtain a reserved hole that meets the requirements of subsequent hoisting operations.

[0051] During the cleaning process, an angle grinder is typically used in conjunction with a wire wheel to grind the cut edges, focusing on removing large burrs and slag. For uneven cut surfaces, a grinding wheel should be used to smooth and grind them to ensure that the unevenness of the cut edges meets the process requirements. After grinding, the oxide layer can be removed by wiping the edge surface with a wire brush and acetone or a special cleaning agent to ensure that the metal substrate is exposed.

[0052] It should be further explained that the purpose of thoroughly cleaning the initial hole edge is not only to ensure that there is no interference when the sleeve is inserted into the hole, but more importantly, to eliminate the potential impact of residual burrs, spatter, and oxide layers on the subsequent beveling quality. If these residues remain on the cutting edge, they will cause local pits or impurity inclusions during subsequent beveling grinding, thus affecting the geometric accuracy of the beveling and the metallurgical quality of the weld, which is detrimental to the sealing and load-bearing capacity of the welded joint. Therefore, the cleaning process is a necessary prerequisite for ensuring the quality of subsequent processes.

[0053] In one embodiment, step S200 includes: S210. Hoist the gate sleeve to the vicinity of the reserved hole.

[0054] Specifically, before carrying out hoisting operations, construction personnel must first develop a specific hoisting plan based on the actual weight, external dimensions, and on-site construction space conditions of the gate sleeve, and rationally select hoisting equipment and matching lifting tools. The rated load-bearing capacity of the lifting tools should not be less than 1.5 times the self-weight of the gate sleeve, and they can only be put into use after passing inspection.

[0055] After the hoisting preparations are complete, the lifting equipment will slowly lift the gate sleeve from the storage area to the vicinity of the pre-drilled hole on the steel lining wall panel, ensuring that the axis of the gate sleeve body is roughly aligned with the center axis of the pre-drilled hole. During the hoisting process, a designated person should be responsible for signaling and directing the operation, maintaining a stable hoisting speed, and strictly prohibiting the sleeve from swinging significantly in the air to prevent collisions with surrounding structures or equipment, which could cause damage to the sleeve body or the steel lining wall panel.

[0056] S220, make the gate sleeve pass through the reserved hole and approach the preset position.

[0057] Specifically, after confirming the correct posture and orientation of the sleeve, the lifting equipment, guided by the signalman, slowly adjusts the sleeve position, driving the sleeve body to gradually penetrate the pre-drilled hole from the outside of the wall panel along the axial direction. During the drilling process, operators should simultaneously observe the gap between the sleeve body and the edge of the pre-drilled hole from both sides of the wall panel to ensure that the sleeve body remains centered in the pre-drilled hole throughout the drilling process, avoiding contact and scraping between the outer wall of the sleeve and the cutting edge of the pre-drilled hole.

[0058] Since the diameter or outline size of the reserved hole formed in step S100 has been left with sufficient operating margin according to the principle of being at least 50mm smaller than the corresponding size of the outer edge of the reinforcing ring plate, the cross-sectional size of the sleeve body is significantly smaller than the reserved hole. Therefore, the sleeve body will not interfere with the wall plate during the perforation process, and the perforation operation can be carried out smoothly.

[0059] Continue advancing the sleeve until the end face of the reinforcing ring plate is close to and approximately parallel to the outer surface of the steel lining wall panel. At this point, the sleeve has reached the vicinity of the preset position. Stop axial advancement and proceed to the fine-tuning stage. During this stage, the lifting equipment should remain under load to provide continuous support to the sleeve and prevent it from tilting and sinking under its own weight.

[0060] S230. Adjust the position of the gate sleeve according to the design elevation, axis and cross center line.

[0061] Specifically, after the sleeve is close to the preset position, the construction personnel need to make systematic and precise adjustments to the installation position of the gate sleeve, covering three dimensions: elevation, axis, and cross center line.

[0062] Regarding elevation adjustment, a level instrument was used to measure the installation elevation of the gate sleeve. The measured elevation was compared with the design elevation required by the drawings. The sleeve was then adjusted to a position that met the allowable elevation deviation requirements through the lifting and fine-tuning operation of the hoisting equipment.

[0063] Regarding axis adjustment, the installation center line marked on the wall panel is used as a reference. A total station or laser plumb line is used to detect the plane position of the sleeve axis, determine the deviation between the sleeve axis and the design axis in the horizontal plane, and eliminate the deviation through the horizontal fine-tuning operation of the lifting equipment to make the sleeve axis coincide with the design axis.

[0064] Regarding the adjustment of the cross center line, the cross center line pre-marked on the reinforcing ring plate is compared with the installation center line marked on the steel lining wall plate in step S100. By gradually fine-tuning the horizontal position of the sleeve, the projections of the two sets of cross center lines on the wall plate surface are made to completely coincide, so as to ensure that the planar positioning accuracy of the sleeve installation meets the process requirements of subsequent secondary cutting and assembly welding.

[0065] S240, Make the corresponding mating surfaces of the reinforcing ring plate and the steel lining wall plate fit tightly together.

[0066] Specifically, after the sleeve position is adjusted to be qualified, with the cooperation of the lifting equipment, the sleeve is slowly moved along the axial direction towards the wall plate, so that the contact surface of the reinforcing ring plate gradually approaches and contacts the outer surface of the steel lining wall plate, until the reinforcing ring plate and the wall plate are fully and tightly fitted.

[0067] During the bonding process, operators should check the bonding status segment by segment along the outer circumference of the reinforcing ring plate, paying particular attention to any abnormalities such as local warping, excessive gaps, or one-sided contact between the reinforcing ring plate and the wall plate. If uneven bonding is found, axial advancement should be stopped immediately, and the sleeve's posture should be finely adjusted to eliminate any tilting deviation of the reinforcing ring plate plane relative to the outer surface of the wall plate before continuing advancement until complete bonding.

[0068] S250. Use temporary fixing fixtures to fix the adjusted gate sleeve; wherein, the temporary fixing fixtures are one of the following: positioning plate, wedge, tensioner or clamp.

[0069] Specifically, after the reinforcing ring plate and the wall plate are tightly fitted and the position is verified to meet the requirements, temporary fixing fixtures should be used immediately to reliably fix the gate sleeve to prevent the sleeve position from shifting due to vibration, thermal deformation or construction disturbance during subsequent cutting, grinding and welding operations, thereby ensuring that the installation accuracy already achieved is maintained until all subsequent processes are completed.

[0070] In this embodiment, the gate sleeve hoisting and drilling process is broken down into five sequentially linked operation steps: hoisting and positioning, drilling and positioning, three-dimensional fine adjustment, mating surface pressing, and temporary fixing. This gradually transitions the gate sleeve from a transport state to a position that meets the installation accuracy requirements. By flexibly selecting various temporary fixing tools, the stable and reliable position of the sleeve is ensured throughout the subsequent construction process. This provides a solid technological guarantee for the high-quality implementation of subsequent processes such as second precise cutting, beveling, and assembly welding.

[0071] In one embodiment, step S400 includes: S410. After fixing the gate sleeve, the outer edge of the reinforcing ring plate is used as a physical reference to determine the second cutting profile.

[0072] Specifically, the second step of determining the cutting profile can only begin after the gate sleeve has been properly positioned and reliably secured by temporary fixtures. It is crucial to emphasize that this step explicitly requires the cutting profile to be calibrated only after the sleeve has been secured. This sequential arrangement is of significant technological importance: if the cutting profile is calibrated before the sleeve is reliably secured, the slight displacement of the sleeve under subsequent operational disturbances will directly cause a relative deviation between the calibrated cutting profile and the actual outer edge of the reinforcing ring plate, resulting in a loss of positioning accuracy for the second cut. Therefore, the order of the fixing and profile calibration steps cannot be reversed.

[0073] After confirming that the sleeve is securely fixed, use the actual outer edge of the reinforcing ring plate as a reference and directly scribing along the outer edge contour of the reinforcing ring plate on the surface of the steel lining wall panel. When scribing, a scribing needle or stone pencil can be used to slide close to the inner side of the outer edge of the reinforcing ring plate, leaving continuous and clear contour lines on the wall panel surface, which serves as the direct basis for determining the contour for the second cutting.

[0074] S420. Leave a 2-3mm beveling allowance between the second cutting contour and the outer edge of the reinforcing ring plate.

[0075] Specifically, the second cutting contour is not drawn directly along the outer edge of the reinforcing ring plate. Instead, it is determined by offsetting the outer edge of the reinforcing ring plate by 2-3 mm towards the side of the wall panel material, so as to form a bevel machining allowance band with a width of 2-3 mm between the cutting line and the outer edge of the reinforcing ring plate.

[0076] The thermal cutting process inherently introduces errors in kerf width and perpendicularity. If the cutting line is directly aligned with the outer edge of the reinforcing ring, unavoidable minor deviations during the cutting operation will cause the cutting surface to intrude into the reinforcing ring body area, resulting in damage to the edge of the reinforcing ring. Simultaneously, the material microstructure and mechanical properties within the heat-affected zone change during cutting. If this zone is directly used as the beveling surface, it will adversely affect the metallurgical quality and mechanical properties of the weld. Therefore, reserving a 2-3mm machining allowance allows for the complete removal of material from the heat-affected zone during the subsequent beveling and grinding process, exposing a beveling surface with normal metallic microstructure. This ensures that the geometric accuracy and material quality of the beveling meet the requirements of the welding procedure specifications.

[0077] S430. The steel lining panel is precision cut according to the second cutting contour.

[0078] Specifically, the steel lining panel is precision-cut according to the marked second cutting contour line. The preferred cutting method for precision cutting is plasma arc cutting, which features a narrow kerf, stable cutting speed, and high surface flatness. It can effectively reduce the geometric deviation of the cut surface and reduce the workload of subsequent beveling and grinding, and is superior to gas cutting in ensuring cutting quality.

[0079] During operation, the operator should maintain a uniform and continuous cutting speed along the cutting contour line. The torch movement path should strictly follow the defined cutting contour line. The cutting process should not be interrupted or the cutting speed changed arbitrarily to avoid defects such as localized depressions, steps, or slag buildup on the cut surface. The starting point of the cut should be selected at a suitable position on the cutting contour line, and the ending point should smoothly connect with the starting point to ensure the closure and continuity of the cutting contour, avoiding misalignment or gaps in the cutting line in the starting and ending arc areas.

[0080] S440. Control the cutting heat input during the precision cutting process to reduce local deformation of the steel lining wall panel.

[0081] Specifically, while performing precision cutting, it is necessary to actively control the heat input during cutting in order to minimize the impact of thermal deformation on the steel lining wall panel and the already positioned gate sleeve caused by the precision cutting process.

[0082] The control of cutting heat input is mainly achieved from the following aspects: First, in terms of cutting parameters, the cutting current, cutting speed, and torch height should be reasonably set according to the material and thickness of the wall panel. Under the premise of ensuring cutting quality, a relatively large cutting speed and a relatively small cutting current combination should be given priority to reduce the amount of heat input per unit length of cutting line. Second, in terms of cutting sequence, the precision cutting operation should be carried out segment by segment according to the overall arrangement of segmented construction in the S500 steps, avoiding continuous application of cutting heat throughout the entire circumference, so as to effectively control the heat accumulation in various parts of the wall panel. Third, in terms of cooling measures, for areas with concentrated heat input, natural cooling or auxiliary cooling measures can be used after cutting. After the wall panel temperature of the construction segment recovers to a reasonable range, the precision cutting operation of the next construction segment can be carried out.

[0083] S450, after cutting, retain the continuous edge allowance required for the bevel to be processed.

[0084] Specifically, after the precision cutting is completed, the cutting edge of the panel is inspected along the entire circumference cutting contour to confirm that a bevel processing allowance of 2-3mm width is continuously retained along the entire circumference, and the allowance edge is continuous and complete, without local breaks, chipping, or edge damage caused by cutting defects.

[0085] It is important to clarify that the continuity of the beveling allowance is a core quality control requirement for this step. If the allowance is interrupted in a localized area, the beveling grinding operation at that location will not have sufficient processing space, and the material in the heat-affected zone will not be completely removed. This will leave a degraded area on the beveling surface, posing a potential threat to the weld quality at that location. Therefore, if insufficient allowance is found in individual locations during inspection, supplementary grinding should be used to locally correct the area, ensuring the continuity and sufficiency of the beveling allowance throughout the entire circumference.

[0086] After the allowance inspection is passed, the cutting edge of the wall panel should be cleaned as necessary to remove the spatter, slag and dust generated during cutting, so that the allowance edge is kept clean. This ensures that the subsequent beveling and grinding work can be effectively carried out on the clean metal substrate surface, and obtain the beveling geometry and surface quality that meet the requirements of the welding process specifications.

[0087] In one embodiment, step S500 includes: S510. Divide the secondary cutting area into multiple segments along the circumferential direction of the gate sleeve.

[0088] Specifically, before carrying out the segmented construction work, it is necessary to first divide the entire circumferential cutting area between the gate sleeve and the steel lining wall panel into several construction segments along the circumference.

[0089] The number of construction sections should be determined comprehensively based on the outer diameter of the gate sleeve, the wall thickness, and the on-site construction conditions. Generally, for medium-sized gate sleeves, the entire circumference can be divided into 4 sections, with each section having approximately equal arc length, and adjacent construction sections are separated by the four equal division points on the circumference. For larger gate sleeves, the number of sections can be increased to 6 or 8 depending on the actual situation, so as to control the operating range of each section within a reasonable length that can be effectively managed by the construction personnel.

[0090] S520. Determine the cutting sequence of each construction section according to the principle of symmetrical distribution.

[0091] Specifically, after the construction sections are divided, the work on each section should not proceed in a clockwise or counterclockwise direction. Instead, the cutting order of each section should be determined according to the principle of symmetrical distribution. That is, construction sections that are symmetrically positioned on the circumference should be selected and worked on alternately.

[0092] If the cutting and welding of each construction section are carried out sequentially in a single direction, the cutting and welding heat will continuously accumulate in localized areas of the wall panel, causing localized thermal expansion and deformation of that side of the wall panel. This will lead to uneven changes in the fit between the reinforcing ring plate and the wall panel, resulting in a shift in the bevel assembly gap of the subsequently unconstructed sections, affecting the uniformity and sealing quality of the weld throughout the circumference. However, by adopting a symmetrical, alternating construction sequence, the heat input can be distributed as evenly as possible in the circumferential direction, and the thermal deformation in each symmetrical direction cancels each other out. This effectively controls the overall stability of the sleeve installation position and ensures the consistency of the construction quality throughout the circumference.

[0093] S530. First, cut one of the construction sections and remove the corresponding excess material, then perform beveling and welding on the corresponding section.

[0094] Specifically, following the established construction sequence, the first construction section is selected, and a precision cutting operation is carried out along the predetermined second cutting contour line of that section. After the cutting is completed, the corresponding wall panel residue is removed from the cutting area, exposing the edge of the bevel to be processed in that section.

[0095] After removing excess material, the cut edges of the wall panels in the construction section are immediately beveled and ground. During grinding, the cut edges should be machined into the specified bevel shape (usually a single-sided V-shaped bevel or a double-sided bevel) according to the welding procedure specifications, ensuring that the bevel angle, blunt edge thickness, and bevel surface flatness all meet the dimensional tolerances specified in the procedure specifications. After grinding, the bevel surface and the wall panel surface within a range of at least 20mm on both sides should be thoroughly cleaned to remove oxide layers, oil stains, and metal dust generated during grinding, ensuring the metallurgical cleanliness of the weld fusion zone.

[0096] S540. Cut another construction section that is opposite or staggered from the already cut construction section at intervals, and perform beveling and welding on the corresponding section.

[0097] Specifically, after the beveling and welding of the first construction section are completed, another construction section that is opposite or staggered from the first construction section on the circumference is selected according to the principle of symmetrical distribution. The precision cutting, removal of excess material, beveling and welding of this section are carried out. The work content and quality requirements are completely consistent with the corresponding procedures of the first construction section.

[0098] It is important to note that the construction segment selected in this step maintains a relative or staggered positional relationship with the previous construction segment in the circumferential direction, rather than being adjacent to the previous construction segment. This is a direct manifestation of the principle of symmetrical distribution at the operational level. By spatially isolating the work positions of adjacent construction cycles, the constraint force exerted on the sleeve by the welded segment is evenly distributed in the circumferential direction, avoiding the accumulation of welding shrinkage stress caused by continuous welding of adjacent segments in local areas, thereby effectively reducing the adverse effects of welding deformation on the sleeve installation accuracy.

[0099] After each section of assembly welding is completed, the welded section should be re-measured and inspected to confirm that the installation position of the sleeve (including elevation, axis, and cross center line) has not shifted beyond the allowable deviation range due to the heat of cutting and welding. If a positional deviation is found to be excessive, corrective measures should be taken in a timely manner, and the work on the subsequent construction section can only continue after the deviation has been eliminated.

[0100] S550. Repeat the steps of first cutting one construction segment and removing the corresponding excess material, then beveling and welding the corresponding segment to another construction segment that is opposite or staggered to the already cut construction segment, and then beveling and welding the corresponding segment, until the full circumference connection construction is completed.

[0101] Specifically, following the symmetrical and alternating construction sequence described above, the remaining construction sections are sequentially and cyclically completed with precision cutting, removal of excess material, beveling, and assembly welding until all construction sections around the perimeter are connected.

[0102] After the completion of the full circumference connection construction, a systematic quality inspection of the weld seams should be conducted. Following a satisfactory visual inspection, non-destructive testing (NDT) should be performed on the weld seams according to the relevant quality acceptance standards for nuclear power plants. Testing methods typically include radiographic testing (RT) and ultrasonic testing (UT) to comprehensively evaluate the internal quality of the weld seams and confirm the absence of any defects exceeding the standards. Only after all inspection items pass the inspection is the full circumference connection construction between the gate sleeve and the steel lining wall panel considered complete, ensuring the reliable sealing integrity of the containment steel lining.

[0103] The entire area to be cut twice was evenly divided into six construction segments along the circumference. The arc length of each segment was approximately the arc length corresponding to a 60° arc. The dividing points of each construction segment were marked on the surface of the wall panel. The cutting sequence was determined according to the principle of symmetrical distribution: Segment 1 (0°-60°), Segment 4 (180°-240°), Segment 2 (60°-120°), Segment 5 (240°-300°), Segment 3 (120°-180°), and Segment 6 (300°-360°). After each segment was precision-cut and excess material removed, the beveling and welding of that segment were immediately performed. After the welding of that segment was completed and passed visual inspection, the work on the next construction segment was carried out in the same order until all six segments were connected. Using a six-segment division method further refines the work area of ​​each segment, which is beneficial for achieving more uniform distribution and control of cutting and welding heat in the circumferential direction in construction situations where operating space is limited or the wall panel is sensitive to thermal deformation, thereby achieving better installation accuracy.

[0104] In one embodiment, step S530 includes: S531. First, cut one of the construction sections and remove the corresponding excess material. After the second cutting of a single section is completed, clean the surface of the hole edge of that section.

[0105] S532. Use the 2-3mm allowance reserved during the second cutting to grind and trim the edge of the hole; S533. Remove the heat-affected layer, oxide layer, and local defects formed during cutting; S534. The edge of the hole is machined to form a bevel structure that meets the welding requirements; S535, check the bevel angle, blunt edge and root gap and complete the assembly welding operation.

[0106] In this embodiment, by refining the single-section bevel grinding and assembly welding operation into five strictly sequential operation steps—hole edge surface cleaning, excess material grinding and trimming, removal of heat-affected layer, oxide layer and local defects, bevel forming processing, and bevel parameter verification and assembly welding—the problem of edge quality deterioration introduced by thermal cutting is systematically solved. This ensures that the bevel working surface of each construction section has a clean metal substrate and precise geometry before entering the welding process, thus providing a reliable process guarantee for all construction sections to meet the high-quality standards required for the sealing integrity of the steel lining of the nuclear power plant containment vessel.

[0107] In one embodiment, step S535 includes: S51. After verifying the bevel angle, blunt edge and root gap and grinding the bevel section, assemble the hole edge of the steel lining wall panel with the corresponding connecting edge of the reinforcing ring plate. S52. Adjust the assembly gap and misalignment to meet welding requirements; S53. Fix the assembled connecting sections by tack welding. S54. Welding operations shall be carried out after the tack welding is fixed; S55. Repeat the steps described above: after verifying the bevel angle, blunt edge, and root gap, and grinding the bevel section, assemble the edge of the hole in the steel lining wall panel with the corresponding connecting edge of the reinforcing ring plate until the welding operation is performed after the positioning welding is fixed, until the full circumference welding is completed.

[0108] In this embodiment, the single-segment assembly welding operation is refined into four strictly interconnected operational steps: assembly after bevel parameter verification, fine adjustment of assembly gap and misalignment, tack welding locking, and formal welding. The full circumferential connection construction is completed in a segment-by-segment cyclical manner, which realizes precise control and reliable locking of the assembly status of each construction segment. This effectively prevents the influence of welding thermal deformation on the assembly accuracy and ensures that the geometric and metallurgical quality of the full circumference weld meets the stringent requirements of the containment steel lining of nuclear power plants for sealing integrity and structural reliability.

[0109] In one embodiment, step S250 includes: S251. After the gate sleeve is adjusted to the preset position, the temporary fixing fixture is installed between the outer periphery of the gate sleeve and the steel lining wall panel. S252. The temporary fixing fixture restricts the radial, axial and circumferential displacement of the gate sleeve; S253. During the segmented cutting process, the center position and fitting status of the gate sleeve are checked; S254. When a deviation trend occurs, adjust the temporary fixing fixture in a timely manner and fix the adjusted gate sleeve.

[0110] In this embodiment, a dynamic control system for the sleeve position is constructed through four closely linked operational links: uniform arrangement and installation of temporary fixing fixtures, comprehensive constraints in the radial, axial and circumferential directions, dynamic position verification during the segmented cutting process, and timely prediction and active adjustment of offset trends. This system effectively prevents the cumulative drift of sleeve position parameters caused by the continuous effects of cutting and welding heat during the segmented construction process, ensuring that the installation position accuracy of the sleeve after the completion of the full circumferential connection construction always meets the strict acceptance requirements of the steel lining project of the nuclear power plant building.

[0111] In one embodiment, after step S55, the method further includes: S56. Remove the temporary fixing fixture.

[0112] In this embodiment, the temporary fixing fixture is removed only after the full circumference welding is completed and the inspection is qualified. The fixture is removed in a symmetrical and synchronous loosening and removal order. At the same time, the sleeve position is re-measured immediately after the removal. This forms a complete closed-loop control process from fixture installation and full-process constraint to orderly removal and final position confirmation. This ensures that the temporary fixing fixture can be safely and orderly removed after completing its phased support and constraint function, without adversely affecting the final installation accuracy of the sleeve and the integrity of the wall panel surface. This provides a reliable prerequisite for the smooth progress of subsequent processes.

[0113] In one embodiment, after step S500, the method further includes: S600, Non-destructive testing and sealing inspection of welds are carried out.

[0114] In this embodiment, by implementing non-destructive testing and sealing inspection in sequence, a closed-loop quality confirmation was completed from two aspects: the internal quality of the weld and the overall sealing performance, providing a complete technical basis for construction quality acceptance.

[0115] The above are merely exemplary embodiments of the present invention and do not limit the scope of the patent of the present invention. All equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A construction method for the on-site installation of a secondary cut of a steel-lined gate sleeve of a nuclear power plant building, characterized in that, Includes the following steps: A first cut is made at the preset installation position on the steel lining wall panel to form a reserved hole; wherein, the gate sleeve is installed at the preset installation position, and the diameter or outline size of the reserved hole is at least 50mm smaller than the corresponding size of the outer edge of the reinforcing ring plate; The gate sleeve is hoisted to the preset position and passed through the reserved hole; Adjust the position of the gate sleeve so that the reinforcing ring plate is in contact with the steel lining wall plate, and the cross center line of the reinforcing ring plate coincides with the cross center line of the steel lining wall plate; Using the outer edge of the reinforcing ring plate as the on-site cutting reference, the steel lining wall panel is cut a second time, with a 2-3mm bevel machining allowance reserved; The secondary cutting area is divided into multiple construction sections along the circumference and implemented section by section. After each section of secondary cutting is completed, the corresponding section is beveled and welded together until the full circumference connection construction is completed.

2. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in claim 1, characterized in that, The step of making a first cut at the predetermined installation position on the steel lining wall panel to form a reserved hole includes: Based on the design drawings and on-site measurement results, the installation center line of the gate sleeve is marked on the steel lining wall panel; The first cutting hole position is determined based on the installation center line; The steel lining wall panel is cut according to the predetermined contour to form the initial holes; Remove burrs, spatter, and oxide layer from the edge of the initial hole to obtain the reserved hole.

3. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in claim 2, characterized in that, The step of hoisting the gate sleeve to the preset position and passing the sleeve through the reserved hole includes: The gate sleeve is hoisted to the vicinity of the reserved hole; The gate sleeve is made to pass through the reserved hole and approach the preset position; The position of the gate sleeve is adjusted according to the design elevation, axis, and cross center line; The reinforcing ring plate is made to fit tightly against the corresponding mating surfaces of the steel lining wall panel; The adjusted gate sleeve is fixed using a temporary fixing fixture; wherein the temporary fixing fixture is one of a positioning plate, a wedge, a tensioner, or a clamp.

4. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in claim 3, characterized in that, The step of using the outer edge of the reinforcing ring plate as the on-site cutting reference to perform a second cut on the steel lining wall panel, and leaving a 2-3mm beveling allowance, includes: After fixing the gate sleeve, the outer edge of the reinforcing ring plate is used as a physical reference to determine the second cutting profile; A 2-3mm beveling allowance is reserved between the second cutting contour and the outer edge of the reinforcing ring plate; The steel lining panel is precision-cut according to the second cutting contour; Controlling the cutting heat input during the precision cutting process reduces local deformation of the steel lining wall panel; After cutting, retain the continuous edge allowance required for the bevel to be processed.

5. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in any one of claims 1 to 4, characterized in that, The process of dividing the secondary cutting area into multiple construction segments along the circumference and implementing the process segment by segment, and then performing beveling and welding on the corresponding segment after each secondary cutting is completed, until the entire circumference connection is completed, includes: The secondary cutting area is divided into multiple segments along the circumference of the gate sleeve; The cutting sequence of each construction section is determined according to the principle of symmetrical distribution; First, cut one of the construction sections and remove the corresponding excess material, then perform beveling and welding on the corresponding section; Cut another construction section that is opposite or staggered from the already cut construction section at intervals, and perform beveling and welding on the corresponding section; Repeat the steps of first cutting one construction segment and removing the corresponding excess material, then beveling and welding the corresponding segment to another construction segment that is opposite or staggered from the already cut construction segment, and then beveling and welding the corresponding segment, until the full circumference connection construction is completed.

6. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in claim 5, characterized in that, The steps of first cutting one construction section and removing the corresponding excess material, and then beveling and welding the corresponding section include: First, cut one of the construction sections and remove the corresponding excess material. After the second cutting of a single section is completed, clean the surface of the hole edge of that section. Use the 2-3mm allowance left during the second cutting to grind and trim the hole edges; Remove the heat-affected layer, oxide layer, and local defects formed during cutting; The hole edges are machined to form a bevel structure that meets welding requirements; Verify the bevel angle, blunt edge, and root gap, and complete the assembly welding operation.

7. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in claim 6, characterized in that, The steps of verifying the bevel angle, blunt edge, and root gap, and completing the assembly welding operation include: After verifying the bevel angle, blunt edge and root gap and grinding the bevel section, the hole edge of the steel lining wall panel is aligned with the corresponding connecting edge of the reinforcing ring plate; Adjust the assembly gap and misalignment to meet welding requirements; The assembled connecting sections are fixed by tack welding; Welding is performed after the tack weld is fixed. Repeat the steps described above: after verifying the bevel angle, blunt edge, and root gap, and grinding the bevel section individually, assemble the edge of the hole in the steel lining wall panel with the corresponding connecting edge of the reinforcing ring plate, and then perform the welding operation after fixing with tack welds, until the full circumference welding is completed.

8. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in claim 7, characterized in that, The step of fixing the adjusted gate sleeve with temporary fixing fixtures includes: After the gate sleeve is adjusted to the preset position, the temporary fixing fixture is installed between the outer periphery of the gate sleeve and the steel lining wall panel; The temporary fixing fixture restricts the radial, axial, and circumferential displacement of the gate sleeve. During the segmented cutting process, the center position and fitting status of the gate sleeve are checked; When a deviation trend occurs, adjust the temporary fixing fixture in a timely manner and fix the adjusted gate sleeve.

9. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in claim 8, characterized in that, After repeating the steps of verifying the bevel angle, blunt edge, and root gap, and grinding the bevel in a single section, assembling the edge of the steel lining wall panel hole with the corresponding connecting edge of the reinforcing ring plate, and then performing the welding operation after fixing by tack welding, until the full circumference welding is completed, the process further includes: Remove the temporary fixing fixture.

10. The secondary cutting construction method for on-site installation of steel-lined gate sleeves in nuclear power plant buildings as described in any one of claims 1 to 4, characterized in that, After dividing the secondary cutting area into multiple construction segments along the circumference and implementing the work segment by segment, and after each segment is completed, beveling and welding are performed on the corresponding segment until the entire circumference connection is completed, the process also includes: Non-destructive testing and sealing inspection were performed on the welds.

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