A high-temperature bolted joint sealing structure analysis and evaluation method

Abstract

This invention belongs to the field of reactor structural mechanics technology, specifically relating to a method for analyzing and evaluating high-temperature bolted connection sealing structures. The invention includes the following steps: selecting the location of the reactor pressure vessel flange and main bolt connection as the object of sealing structure analysis; analyzing and summarizing the influence of gasket data on the deformation and contact surface pressure of various components of the flange bolted connection structure; researching current standards and analyzing their limitations; using the finite element software ANSYS to perform finite element modeling of the reactor pressure vessel flange and main bolt structure; applying loads and constraints to the finite element model of the reactor pressure vessel flange and main bolt structure; calculating the deformation and stress of the structure using different creep and relaxation models; analyzing the relaxation behavior of the high-temperature flange bolted connection structure using experimental methods; and comparing and analyzing the results of the finite element method, the standard method, and the experimental method. This invention enables the analysis and evaluation of the sealing performance of flange bolted connection structures under high-temperature environments.

Description

Technical Field

[0001] This invention belongs to the field of reactor structural mechanics technology, specifically relating to a method for analyzing and evaluating high-temperature bolted connection sealing structures. Background Technology

[0002] Fourth-generation nuclear reactors, compared to third-generation pressurized water reactors, are designed to operate at higher temperatures to improve economic efficiency. However, high-temperature conditions pose more severe challenges to the mechanical behavior of structural materials, especially bolted connections, which are prone to creep and stress relaxation under long-term high-temperature environments, seriously affecting their sealing performance and structural integrity.

[0003] Currently, the design of pressure vessels and flange connection systems widely adopts ASME standards and European standards EN1591-1 and EN13555. These standards provide sealing design methods based on gasket relaxation behavior and have good applicability in many engineering designs. However, they have a significant limitation: they only consider the relaxation behavior of the gasket and do not take into account the creep effect of the flange or bolt materials. In actual high-temperature environments, the creep of the flange material of the bolts can also lead to a decrease in preload and a redistribution of stress on the sealing surface, thereby increasing the risk of leakage. This phenomenon is particularly prominent in high-temperature reactors (such as sodium-cooled fast reactors and lead-cooled fast reactors).

[0004] Recent studies have shown that neglecting the creep behavior of structural materials may lead to overly optimistic estimates of the seal life of bolted connection systems. For example, finite element analysis has revealed that at temperatures above 600°C, creep in flange and bolt materials significantly accelerates the stress relaxation process of the connection structure. Other experimental studies have indicated that traditional design methods may underestimate the risk of seal failure due to the creep-relaxation coupling effect under high-temperature conditions. Although some academic research has attempted to incorporate material creep into the seal analysis of connection structures, a systematic and engineering-applicable evaluation method is still lacking that can uniformly consider the coupled creep-relaxation behavior of bolts, flanges, and gaskets under high-temperature conditions.

[0005] Therefore, existing standard analytical methods are significantly insufficient when dealing with high-temperature operating conditions such as fourth-generation reactors, and there is an urgent need to develop a more comprehensive evaluation system for the sealing performance of high-temperature bolted connections. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a method for analyzing and evaluating the sealing performance of flange bolt connection structures under high-temperature conditions.

[0007] The technical solution adopted in this invention is as follows:

[0008] A method for analyzing and evaluating the sealing structure of a high-temperature bolted connection includes the following steps:

[0009] Step 1: Select the location of the reactor pressure vessel flange and main bolt connection as the object of the sealing structure analysis. The vessel top cover and the vessel flange are connected by main bolts and main nuts.

[0010] Step 2: Under high temperature conditions, analyze and summarize the effects of gasket creep behavior, material creep behavior, bolt relaxation behavior, and structural temperature distribution on the deformation and contact pressure of various components of the flange bolt connection structure, thereby evaluating the impact of these factors on sealing performance.

[0011] Step 3: Investigate the existing standards, analyze their limitations, and use the standard's analytical methods to analyze the vessel flange and main bolt structure, obtaining the creep of the vessel flange, bolts, and gaskets in each time increment, as well as the residual bolt stress and creep strain at the end of that time increment.

[0012] Step 4: Use the finite element software ANSYS to perform finite element modeling on the reactor pressure vessel flange and main bolt structure to obtain the finite element model of the reactor pressure vessel flange and main bolt structure.

[0013] Step 5: Apply loads and constraints to the finite element model of the reactor pressure vessel flange and main bolt structure. The loads include internal pressure, preload, and temperature loads. Apply symmetric constraints to the symmetry plane and constrain the axial degrees of freedom at the bottom of the model.

[0014] Step 6: Calculate the deformation and stress of the structure using different creep and relaxation models, obtain the result matrix, and evaluate the sealing performance of the structure based on the deformation results;

[0015] Step 7: Analyze the relaxation behavior of the high-temperature flange bolt connection structure using experimental methods to obtain the deformation results of the structure;

[0016] Step 8: Compare and analyze the results of the finite element method, the standard method, and the experimental method.

[0017] The analytical method described in the specification is as follows:

[0018] Assuming a dominant stress direction exists in the vessel flange, treating it as a uniaxial creep problem directly related to the flange strength; using this simplified method, the time-varying bolt relaxation stress is determined through iterative calculations in small time increments; assuming the connection structure is deformation-controlled after assembly, and that the sum of any changes in component deformation must equal zero, the following governing equations are obtained:

[0019] Δl be +Δl bc +Δl fe +Δl fc +Δl ge+Δl gc =Δl bi +Δl fi +Δl gi (1)

[0020] The above formula is used to calculate the creep of flanges, bolts, and gaskets in each time increment, as well as the residual bolt stress and creep strain at the end of that time increment. These values ​​are used as inputs to determine the creep strain that will occur in each component in the next time increment.

[0021] Bolt deformation increment E b Let σ be the elastic modulus of the bolt. bi For bolt stress, L bi This represents the amount of bolt deformation.

[0022] Flange deformation increment in A b n is the tensile area of ​​the bolt. b E represents the number of bolts. f Let g be the flange elastic modulus, g0 be the small end hub thickness, L and V be the flange factor, and h be the flange elastic modulus. g This is the distance from the shim reaction force to the bolt circumference.

[0023] Deformation increment of gasket in A g E represents the area of ​​the gasket. g For the elastic modulus of the gasket, t g For the thickness of the gasket;

[0024] Creep strain ε of flange fc =ε fc0 +Δε fc ,in For tangential stress, Let A be the initial creep strain and A be the flange outer diameter.

[0025] Bolt stress

[0026] Where t is the flange thickness, B is the flange inner diameter, Y and e are the flange factors, and ε gc , ε fc and ε bc The creep strains are for the gasket, flange, and bolt, respectively.

[0027] The creep model obtains material creep data in finite element simulation through Norton constitutive model (see formula (2)) and Omega constitutive model (see formula (3));

[0028] The relaxation models, namely the Bailey relaxation model and the Johnson relaxation model, obtain material relaxation data in finite element simulations.

[0029] The Norton constitutive

[0030] (2)

[0031] in, It is the creep strain rate; For stress; , It is a material constant of the Norton constitutive model that is temperature-dependent.

[0032] The Omega constitutive

[0033]

[0034] Where, Δε c It is the creep strain increment corresponding to the time increment dt;

[0035] A, N, and m are material constants, where N is the material constant of the temperature-dependent Omega constitutive model.

[0036] σ0 and ε c0 The initial stress and initial creep strain are for the time increment step.

[0037] The Bailey relaxation model

[0038]

[0039] Where t is time, f is stress, E is elastic modulus, and A and n are material constants of the Bailey relaxation model.

[0040] The Johnson relaxation model

[0041]

[0042] Where A = B / E p+1 t is time, f is stress, f0 is initial stress, E is elastic modulus, A, n, B, p, N are material constants of Johnson relaxation model, and b = 1 - (Eα / f0).

[0043] The experimental method includes the following steps:

[0044] Drill a center hole at the designated location on the flange ring, and assemble bolts, nuts, and gaskets; record the metal temperature of the bolts and flange; measure the initial length of each bolt and the initial distance between the center holes of each pair of flanges; heat the connection joint in the furnace while monitoring it using thermocouples;

[0045] The furnace temperature rises rapidly and remains stable at a high temperature for 12 hours; the furnace stops heating, the furnace door is opened, and the thermocouple is continuously monitored; the connector is removed from the furnace, cooled to room temperature, the metal temperature of the bolts and flanges is recorded, and the oxide at the center drill hole is cleaned.

[0046] The connector is placed back into the furnace for heating, and a thermocouple is installed for monitoring; the furnace temperature rises rapidly and is maintained at a stable temperature of 500℃ for 4 hours; the above steps are repeated and the data is recorded;

[0047] The joint is placed back into the furnace for heating, and a thermocouple is installed for monitoring. The furnace temperature rises rapidly and is maintained at a stable temperature of 500℃ for 16 hours. The above steps are repeated and the final measurement value is recorded to obtain the deformation value of the structure.

[0048] The results of the comparative analysis of the finite element method, the standard method and the experimental method are used, and the deformation and stress results of the structure are obtained through numerical analysis.

[0049] The beneficial effects of this invention are:

[0050] (1) The high-temperature bolted connection sealing structure analysis and evaluation method of the present invention takes into account both the relaxation behavior of the bolted connection structure and the creep behavior of the material, and establishes a more realistic creep-relaxation coupling model, thereby reducing the risk of high-temperature sealing evaluation.

[0051] (2) The present invention provides a method for analyzing and evaluating high-temperature bolted connection sealing structures. Through numerical analysis, it can accurately analyze and evaluate flange bolted connection structures under any working conditions and materials in a high-temperature environment. It comprehensively considers the relaxation behavior of the structure and the creep behavior of the material, thereby improving the safety and reliability of the evaluation results.

[0052] (3) The method for analyzing and evaluating the sealing structure of high-temperature bolted connections of the present invention has important engineering significance for the sealing analysis and evaluation of bolted connection structures under high-temperature environments, and helps engineering designers to conduct sealing analysis of flange bolted connection structures under high-temperature environments efficiently and reliably. Attached Figure Description

[0053] To more clearly illustrate the embodiments of the present invention, the accompanying drawings used in describing the embodiments of the present invention will be briefly described below. Obviously, the drawings described below are merely some embodiments recorded in the present invention. Those skilled in the art can derive other drawings from the following drawings without any creative effort.

[0054] Figure 1 This is a flowchart of an analysis and evaluation method for a high-temperature bolted connection sealing structure according to the present invention;

[0055] Figure 2 This is a schematic diagram of the flange and main bolt connection of the reactor pressure vessel.

[0056] In the diagram: 1-Container top cover, 2-Main nut, 3-Gasket, 4-Main bolt, 5-Container flange, 6-Container body, 7-Sealing surface. Detailed Implementation

[0057] 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0058] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., refer to the orientation or positional relationship shown in the accompanying drawings, and are used only for the convenience of describing the 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 the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0059] 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 a 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.

[0060] like Figure 1 As shown, the present invention provides a method for analyzing and evaluating the sealing structure of a high-temperature bolted connection, comprising the following steps:

[0061] Step 1: Select the location of the reactor pressure vessel flange and main bolt connection as the object of the sealing structure analysis, such as... Figure 2 As shown, the pressure vessel flange and main bolts are axisymmetric structures. Figure 2 This is 1 / 6 of the entire structure. The components of the structure are as follows: 1. Container top cover; 2. Main nut; 3. Washer; 4. Main bolt; 5. Container flange; 6. Container cylinder; 7. Sealing surface. See details for specific locations. Figure 2The container top cover 1 and the container flange 5 are connected by main bolts 4 and main nuts 2;

[0062] Step 2: Under high temperature conditions, analyze and summarize the effects of factors such as the creep behavior of the gasket, the creep behavior of the material, the relaxation behavior of the bolts, and the temperature distribution of the structure on the deformation and contact pressure of each component of the flange bolt connection structure, so as to evaluate the impact of these factors on the sealing performance.

[0063] Step 3: Investigate existing standards, analyze their limitations, and use the standard's analytical methods to analyze the reactor pressure vessel flange and main bolt structure; obtain the creep of the flange, bolts, and gaskets in each time increment, as well as the residual bolt stress and creep strain at the end of that time increment;

[0064] The analytical method described in the specification is as follows: The influence of creep on the connection interaction is calculated by making some simplifying assumptions. It is assumed that there is a dominant stress direction in the flange, which can be treated as a uniaxial creep problem directly related to the flange strength. Using this simplified method, the bolt relaxation stress varying with time is determined by employing an iterative (finite difference) method with small time increments. Assuming that the connection structure is deformation-controlled after assembly, and that the sum of any changes in component deformation must be equal to zero, the following governing equations can be obtained:

[0065] Δl be +Δl bc +Δl fe +Δl fc +Δl ge +Δl gc =Δl bi +Δl fi +Δl gi (1)

[0066] in,

[0067] Bolt deformation increment E b Let σ be the elastic modulus of the bolt. bi For bolt stress, L bi This represents the amount of bolt deformation.

[0068] Flange deformation increment in A b n is the tensile area of ​​the bolt. b E represents the number of bolts. f Let g be the flange elastic modulus, g0 be the small end hub thickness, L and V be the flange factor, and h be the flange elastic modulus. g This is the distance from the shim reaction force to the bolt circumference.

[0069] Deformation increment of gasket in A g E represents the area of ​​the gasket. g For the elastic modulus of the gasket, t g For the thickness of the gasket;

[0070] Creep strain ε of flange fc =ε fc0 +Δε fc ,in For tangential stress, Let A be the initial creep strain and A be the flange outer diameter.

[0071] Bolt stress

[0072] Where t is the flange thickness, B is the flange inner diameter, Y and e are the flange factors, and ε gc , ε fc and ε bc The creep strains are for the gasket, flange, and bolt, respectively.

[0073] Using formula (1), the creep of flanges, bolts and gaskets in each time increment can be calculated, as well as the residual bolt stress and creep strain at the end of that time increment. These values ​​are used as inputs to determine the creep strain that will occur in each component in the next time increment.

[0074] This method, which determines bolt load loss and subsequently gasket stress based on the simplified closed-form solution of the equation, is reasonable and relatively easy to apply. However, if material properties are inaccurate, it is impossible to predict the accurate bolt load loss, thus making it impossible to accurately calculate structural deformation.

[0075] Step 4: Use the finite element software ANSYS to perform finite element modeling on the reactor pressure vessel flange and main bolt structure, obtaining the finite element model of the reactor pressure vessel flange and main bolt structure, such as... Figure 2 As shown;

[0076] Step 5: Apply loads and constraints to the finite element model of the reactor pressure vessel flange and main bolt structure. The loads include internal pressure, preload, and temperature loads. Apply symmetric constraints to the symmetry plane and constrain the axial degrees of freedom at the bottom of the model.

[0077] Step 6: Calculate the deformation and stress of the structure using different creep and relaxation models to obtain the result matrix, which facilitates comparison with the standard method and experimental method. The creep constitutive models are Norton constitutive (see formula (2)) and Omega constitutive (see formula (3)).

[0078] (2)

[0079] in, It is the creep strain rate; For stress; , It is a material constant of the Norton constitutive model that is temperature-dependent.

[0080]

[0081] Where, Δε c It is the creep strain increment corresponding to the time increment dt;

[0082] A, N, and m are material constants, where N is the material constant of the temperature-dependent Omega constitutive model.

[0083] σ0 and ε c0 The initial stress and initial creep strain are for the time increment step.

[0084] The relaxation models used were the Bailey relaxation model (see formula (4)) and the Johnson relaxation model (see formula (5));

[0085]

[0086] Where t is time, f is stress, E is elastic modulus, and A and n are material constants of the Bailey relaxation model.

[0087]

[0088] Where A = B / E p+1 t is time, f is stress, f0 is initial stress, E is elastic modulus, A, n, B, p, N are material constants of Johnson relaxation model, and b = 1 - (Eα / f0).

[0089] The stress and deformation results of each component of the structure are finally calculated, and the sealing performance of the structure is evaluated based on the deformation results.

[0090] Step 7: Analyze the relaxation behavior of the high-temperature flange bolt connection structure using experimental methods to obtain the deformation results of the structure;

[0091] The experimental steps are as follows:

[0092] 1. Processing stage:

[0093] Drill a center hole at the designated location on the flange ring, and then measure and assemble.

[0094] Assemble bolts, nuts, and washers; record the metal temperature of bolts and flanges; measure the initial length of each bolt and the initial distance between the center holes of each pair of flanges; heat the connection joint in the furnace while monitoring it using thermocouples;

[0095] 2. Initial relaxation phase:

[0096] The furnace temperature rises rapidly and remains stable at a high temperature (e.g., 500°C) for 12 hours; the furnace stops heating, the furnace door is opened for rapid air cooling, and the thermocouple is continuously monitored; the joint is removed from the furnace, cooled to room temperature, the metal temperature of the bolts and flanges is recorded, and the oxide at the center drill hole is cleaned.

[0097] 3. Relaxation Phase Two:

[0098] The connector is placed back into the furnace for heating, and a thermocouple is installed for monitoring; the furnace temperature rises rapidly and is maintained at a stable temperature of 500℃ for 4 hours; the above steps are repeated and the data is recorded;

[0099] 4. Final relaxation stage:

[0100] The joint is placed back into the furnace for heating, and a thermocouple is installed for monitoring. The furnace temperature rises rapidly and is maintained at a stable temperature of 500℃ for 16 hours. The above steps are repeated and the final measurement value is recorded to obtain the deformation value of the structure.

[0101] Step 8: By comparing and analyzing the results of the finite element method, the standard method, and the experimental method, a set of parameters for the constitutive model of the high-temperature flange bolt sealing structure is obtained. At the same time, the deformation and stress results of the structure are obtained through numerical analysis, thereby establishing a set of evaluation methods for the high-temperature flange bolt sealing structure based on numerical analysis.

[0102] While those skilled in the art will recognize that the present invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention, the embodiments should be considered illustrative and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and therefore all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0103] Furthermore, it should be understood that although the present invention is described according to embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for analyzing and evaluating the sealing structure of a high-temperature bolted connection, characterized in that, Includes the following steps: Step 1: Select the location of the reactor pressure vessel flange and main bolt connection as the object of the sealing structure analysis. The vessel top cover and the vessel flange are connected by main bolts and main nuts. Step 2: Under high temperature conditions, analyze and summarize the effects of gasket creep behavior, material creep behavior, bolt relaxation behavior, and structural temperature distribution on the deformation and contact pressure of various components of the flange bolt connection structure, thereby evaluating the impact of these factors on sealing performance. Step 3: Investigate the existing standards, analyze their limitations, and use the standard's analytical methods to analyze the vessel flange and main bolt structure, obtaining the creep of the vessel flange, bolts, and gaskets in each time increment, as well as the residual bolt stress and creep strain at the end of that time increment. Step 4: Use the finite element software ANSYS to perform finite element modeling on the reactor pressure vessel flange and main bolt structure to obtain the finite element model of the reactor pressure vessel flange and main bolt structure. Step 5: Apply loads and constraints to the finite element model of the reactor pressure vessel flange and main bolt structure. The loads include internal pressure, preload, and temperature loads. Apply symmetric constraints to the symmetry plane and constrain the axial degrees of freedom at the bottom of the model. Step 6: Calculate the deformation and stress of the structure using different creep and relaxation models, obtain the result matrix, and evaluate the sealing performance of the structure based on the deformation results; Step 7: Analyze the relaxation behavior of the high-temperature flange bolt connection structure using experimental methods to obtain the deformation results of the structure; Step 8: Compare and analyze the results of the finite element method, the standard method, and the experimental method.

2. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 1, characterized in that, The analytical method described in the specification is as follows: Assuming a dominant stress direction exists in the vessel flange, treating it as a uniaxial creep problem directly related to the flange strength; using this simplified method, the time-varying bolt relaxation stress is determined through iterative calculations in small time increments; assuming the connection structure is deformation-controlled after assembly, and that the sum of any changes in component deformation must equal zero, the following governing equations are obtained: （1） The above formula is used to calculate the creep of flanges, bolts, and gaskets in each time increment, as well as the residual bolt stress and creep strain at the end of that time increment. These values ​​are used as inputs to determine the creep strain that will occur in each component in the next time increment.

3. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 2, characterized in that, Bolt deformation increment , The elastic modulus of the bolt. For bolt stress, This represents the amount of bolt deformation. Flange deformation increment ,in , This represents the area of ​​the bolt tension. The number of bolts. For the elastic modulus of the flange, For the thickness of the small end hub, and For flange factor, This is the distance from the shim reaction force to the bolt circumference. Deformation increment of gasket ,in , For the area of ​​the gasket, The elastic modulus of the gasket. For the thickness of the gasket; Creep strain of flange ,in , For tangential stress, For the initial creep strain, The outer diameter of the flange; Bolt stress ; ,in For flange thickness, For the flange inner diameter, and For flange factor, , and The creep strains are for the gasket, flange, and bolt, respectively.

4. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 3, characterized in that, The creep model obtains material creep data in finite element simulation through Norton constitutive model (see formula (2)) and Omega constitutive model (see formula (3)); The relaxation models, namely the Bailey relaxation model and the Johnson relaxation model, obtain material relaxation data in finite element simulations.

5. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 4, characterized in that, The Norton constitutive （2） in, It is the creep strain rate; For stress; , It is a material constant of the Norton constitutive model that is temperature-dependent.

6. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 4, characterized in that, The Omega constitutive （3） in, It is a time increment The corresponding creep strain increment; , and It is a material constant. These are the material constants of the temperature-dependent Omega constitutive model; and The initial stress and initial creep strain are for the time increment step.

7. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 4, characterized in that, The Bailey relaxation model （4） in, For time, For stress, For elastic modulus, , These are the material constants for the Bailey relaxation model.

8. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 4, characterized in that, The Johnson relaxation model （5） in, , For time, For stress, For initial stress, For elastic modulus, , , , , These are the material constants for the Johnson relaxation model. .

9. The method for analyzing and evaluating the sealing structure of high-temperature bolted connections according to claim 4, characterized in that, The experimental method includes the following steps: Drill a center hole at the designated location on the flange ring, and assemble bolts, nuts, and gaskets; record the metal temperature of the bolts and flange; measure the initial length of each bolt and the initial distance between the center holes of each pair of flanges; heat the connection joint in the furnace while monitoring it using thermocouples; The furnace temperature rises rapidly and remains stable at a high temperature for 12 hours; the furnace stops heating, the furnace door is opened, and the thermocouple is continuously monitored; the connector is removed from the furnace, cooled to room temperature, the metal temperature of the bolts and flanges is recorded, and the oxide at the center drill hole is cleaned. The connector is placed back into the furnace for heating, and a thermocouple is installed for monitoring; the furnace temperature rises rapidly and is maintained at a stable temperature of 500℃ for 4 hours; the above steps are repeated and the data is recorded; The joint is placed back into the furnace for heating, and a thermocouple is installed for monitoring. The furnace temperature rises rapidly and is maintained at a stable temperature of 500℃ for 16 hours. The above steps are repeated and the final measurement value is recorded to obtain the deformation value of the structure.

10. The method for analyzing and evaluating the sealing structure of a high-temperature bolted connection according to claim 9, characterized in that, The results of the comparative analysis of the finite element method, the standard method and the experimental method are used, and the deformation and stress results of the structure are obtained through numerical analysis.

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