Method and device for judging sealing performance of end socket and welding neck flange direct connection structure and medium

Abstract

The invention provides a method and device for judging the sealing performance of an end socket and welding neck flange direct connection structure and a medium, and belongs to the technical field of pressure vessel design. The method comprises the following steps: regarding a sealing head and a welding neck flange as an elastic continuum, and establishing a deformation coordination equation under the combined action of internal pressure, bolt pre-tightening force and temperature load; the total bending moment is solved through a deformation coordination condition simultaneous equation at the joint of the end socket and the flange; based on the total bending moment and the section inertia moment of the flange neck, the deflection amount of the flange is calculated; according to the gasket material parameters and the initial thickness, theoretical allowable deformation is determined; and introducing a safety coefficient to correct the allowable deformation of the gasket, comparing the allowable deformation with the flange deflection, and if the flange deflection is smaller than the allowable deformation of the gasket, judging that the sealing performance is qualified. According to the method, the superposed bending moment and the sealing performance of the connecting structure can be calculated more accurately, so that the calculation precision is improved, and the sealing performance and the operation reliability of equipment are improved.

Description

Technical Field

[0001] The invention relates to a method, a device and a medium for determining the sealing performance of a direct connection structure between a head and a high-neck flange, and belongs to the technical field of pressure vessel design. Background Art

[0002] To meet the requirement for independent calculation of flanges and heads, current standards require a cylindrical transition section between the flanges and heads. In pressure-bearing equipment with large agitators, a direct connection between the head and high-neck flange is often used to reduce maintenance difficulties and costs, enhance structural compactness and connection rigidity, and facilitate assembly and disassembly of the agitator. This structure is more commonly used in intermittently operated quick-opening reactors and heat exchanger tube boxes without lateral openings.

[0003] Traditional design and calculation methods typically treat flanges and heads as independent components, ignoring the interaction at the connection. This leads to inaccurate bending moment calculations and insufficient sealing performance. Especially under high pressure or alternating loads, the complex stresses at the flange-head connection can easily cause leakage. The existing technology lacks methods for calculating the superimposed bending moments and optimizing seals after the two are directly connected, and there is no fully corresponding analytical calculation process. To meet standard requirements, the finite element method is often used in engineering projects. However, the finite element method is a complex calculation process that requires continuous model adjustment and repeated trial calculations, resulting in long calculation cycles and low efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a method, device and medium for determining the sealing performance of a structure directly connected between a head and a high-neck flange, thereby solving the problem of inaccurate bending moment calculation and insufficient sealing performance caused by treating the flange and the head as independent components and ignoring the interaction at the connection in traditional design and calculation methods.

[0005] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions: A method for determining the sealing performance of a direct connection structure between a head and a high-neck flange comprises the following steps: The head and high-neck flange are regarded as elastic continuum, and the deformation coordination equation under the combined action of internal pressure, bolt preload and temperature load is established. The total bending moment is solved by solving the simultaneous equations of deformation coordination conditions at the connection between the head and the flange; Calculate the flange deflection based on the total bending moment and the flange neck section moment of inertia; Determine the theoretical allowable deformation based on the gasket material parameters and initial thickness; A safety factor is introduced to correct the allowable deformation of the gasket and compared with the flange deflection. If the flange deflection is less than the allowable deformation of the gasket, the sealing is judged to be qualified.

[0006] Preferably, the total bending moment in step S2 is The calculation formula is: , in: is the flange bending moment caused by internal pressure, is the additional bending moment generated by the bolt preload, is the equivalent diameter of the head, is the curvature radius of the neutral layer of the head, is the thickness of the head, is the flange neck height, is the design internal pressure, is the Poisson's ratio of the material.

[0007] Preferably, the flange deflection The calculation formula is as follows: , in, is the elastic modulus of the flange metal material at the design temperature, is the flange neck section moment of inertia, and the calculation formula is: , in, The outer diameter of the flange neck large end, is the inner diameter of the flange neck.

[0008] Preferably, the gasket theoretically allows deformation The calculation formula is: , in, is the allowable compressive stress of the gasket, is the initial thickness of the gasket, is the equivalent elastic modulus of the gasket.

[0009] Preferably, the equivalent elastic modulus of the gasket is selected according to the material: 3850 MPa for metal wound gaskets and 160 MPa for non-metallic gaskets.

[0010] Preferably, the modified gasket allows deformation for: , in, is the safety factor, which is 2.

[0011] A device for determining the sealing performance of a direct-connected structure between a head and a high-neck flange comprises a processor and a memory storing program instructions. The processor is configured to execute a method for determining the sealing performance of a direct-connected structure between a head and a high-neck flange when running the program instructions.

[0012] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the method for determining the sealing performance of a direct connection structure between a head and a high-neck flange.

[0013] The advantages of the present invention are: This invention solves the problem of inaccurate bending moment calculations and insufficient sealing performance caused by treating flanges and end caps as independent components in traditional design and calculation methods, while ignoring the interaction at the connection. By considering the combined effects of internal pressure, bolt preload, and temperature loads, and establishing a deformation coordination equation, the present invention can more accurately calculate the superimposed bending moment and sealing performance of the connection structure, thereby improving the accuracy of the calculation. Furthermore, the method of the present invention avoids the complex calculation process of the traditional finite element method, which requires continuous model adjustment and repeated trial calculations, significantly improving computational efficiency.

[0014] The method of this invention can be directly used to verify the sealing performance of a direct connection between a head and a high-neck flange. If the verification fails, the design can be optimized by adjusting parameters such as the flange neck height or the head thickness until the sealing performance requirements are met. This structural design method based on precise calculations helps optimize structural dimensions, improve structural compactness and connection rigidity, and reduce maintenance difficulties and costs.

[0015] The calculation method of this invention is applicable to a variety of operating conditions and complex boundary conditions, such as high pressure, alternating loads, and other harsh environments, and has broad engineering application value. In particular, in pressure-bearing equipment with large agitators, intermittently operated quick-opening reactors, and heat exchanger manifolds without lateral openings, where direct connections between heads and high-neck flanges are common, the application of this invention will help improve the sealing performance and operational reliability of these devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0017] Figure 1 Schematic diagram of the process of the present invention.

[0018] Figure 2 This is a schematic diagram of the high-neck flange-head connection structure of the present invention.

[0019] Figure 3 This is an enlarged view of the local structure of the high-neck flange of the present invention.

[0020] Figure 4 It is a schematic diagram of the mechanical model of the high-neck flange and elliptical head of the present invention.

[0021] In the figure: 1. Head; 2. Head straight edge; 3. Flange; 4. Flange straight edge; 5. Flange neck; 6. Flange plate; 7. Gasket. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0023] Example 1 like Figures 1-4 As shown, a method for determining the sealing performance of a direct connection structure between a head and a high-neck flange includes the following steps: S1: Mechanical model analysis, the head and high-neck flange are regarded as elastic continua, and the deformation coordination equation under the combined action of internal pressure, bolt preload and temperature load is established.

[0024] like Figure 2 As shown, the high-neck flange is directly connected to the head, and its main structure includes two parts: the head 1 and the flange 3, and does not include the transition cylinder; the lower end of the head 1 is connected to the high-neck flange by welding to form a whole; the head 1 is usually a standard ellipse, and the ratio of the major axis of the ellipse to the minor axis of the ellipse is usually 2.0; the flange 3 is a high-neck flange, which is characterized in that there is a long and inclined flange neck 5 between the flange straight edge 4 and the flange plate 6, and the wall thickness of the flange neck gradually transitions to the same thickness as the head along the height direction.

[0025] The head 1 and flange 3 are regarded as elastic continua, and the combined effects of internal pressure, bolt preload and temperature load are considered to establish the deformation coordination equation.

[0026] S2: Solve the total bending moment by solving the simultaneous equations of the deformation coordination conditions at the connection between the head and the flange.

[0027] S3: Calculate the flange deflection based on the total bending moment and the flange neck section moment of inertia.

[0028] S4: Determine the theoretical allowable deformation based on the gasket material parameters and initial thickness.

[0029] S5: Introduce a safety factor to correct the allowable deformation of the gasket and compare it with the flange deflection. If the flange deflection is less than the allowable deformation of the gasket, the sealing is judged to be qualified.

[0030] In some embodiments, step S1 specifically includes: S11: Flange mechanical model: The flange neck 5 in the high-neck flange 3 is regarded as a cantilever beam, which bears the axial force caused by the internal pressure. , bending moment , and the bolt force The additional bending moment generated .

[0031] S12: Head mechanical model: The edge displacement of head 1 is calculated according to the thin shell theory, and the internal pressure causes radial displacement and corners , generating transverse shear force at the connection and bending moment .

[0032] Step S1 rationally simplifies the mechanical models of the head and flange, aiming to balance computational efficiency and engineering accuracy. The flange's bending stiffness is much higher than the flange's neck, making it a rigid support. Therefore, the high-neck flange's neck is treated as a cantilever beam, considering only the axial bending moment caused by internal pressure and bolt force, while ignoring the flange's shear deformation and hoop stress.

[0033] The thickness of the head is relatively thin, the membrane stress is dominant, and the edge bending moment at the connection between the head and the flange decays rapidly. It is only necessary to introduce the displacement boundary condition into the coordination equation without the need for a global solution. Therefore, the standard elliptical head is regarded as a thin shell structure, and the edge displacement is calculated based on the membrane theory of the rotating shell. and corners , neglecting the higher-order effects of local bending stresses.

[0034] Compared with the combined model, the simplified model overestimates the deflection by ≤5%, which is conservative and safe.

[0035] In some embodiments, step S2 includes: Through the deformation compatibility condition (equal rotation angles at the connection), the simultaneous equations are: .

[0036] Total bending moment: ; Where: The flange bending moment caused by internal pressure is determined by the design internal pressure Obtained by integrating with the flange geometric dimensions, unit: N⋅mm; is the additional bending moment generated by the bolt preload, and is the bolt force and lever arm The product of, in N⋅mm; is the equivalent diameter of the head (the inner diameter of the straight edge section), unit: mm; Design internal pressure, unit: MPa or N / mm 2 ; is the curvature radius of the neutral layer of the head, in mm; is the Poisson's ratio of the material, dimensionless; is the thickness of the head, in mm; is the flange neck height, in mm.

[0037] The parameters in the total bending moment calculation formula must meet dimensional consistency. 、 、 、 The unit is millimeter; The unit is MPa, 1MPa=1N / mm 2 ; The unit of bending moment result is N·mm.

[0038] In the total bending moment calculation formula, for the standard elliptical head (2:1), , It can be obtained from the ASME II-D material properties table. For metal materials, it is usually taken as 0.3 (carbon steel) ~ 0.33 (stainless steel).

[0039] In the total bending moment calculation formula, the pressure applicable range is ≤10MPa, temperature applicable range ≤350℃.

[0040] Step S2: Turn the corner of the head edge The simultaneous equations couple the membrane deformation of the head with the beam bending response of the flange, providing clear physical meaning and efficient computation. This model is compatible with the independent verification processes in GB / T150.3-2024 and GB / T4732.3-2024, facilitating integration with engineering software. Finite element verification demonstrates a calculation error of ≤5%, meeting the accuracy requirements of engineering design.

[0041] Existing standards treat flanges and heads as independent components, ignoring their deformation coordination, resulting in conservative bending moment calculations or significant errors (especially under high pressure). The total bending moment calculation formula in step S2, by combining the head edge displacement and flange rotation angle, couples the head curvature effect and flange neck stiffness for the first time, analyzing the interaction between the head and flange. Compared with traditional methods, this formula reduces calculation errors and improves the reliability of sealing calculations.

[0042] The total bending moment calculation formula in step S2 replaces the numerical iterative calculation with an explicit analytical solution, which significantly improves the calculation efficiency and is particularly suitable for quickly determining the main structure size in the early stage of design.

[0043] The total bending moment calculation formula in step S2 can be expanded from the standard elliptical head to the dished head, and can cover multiple working conditions and complex boundary conditions. On the premise that temperature and pressure correction coefficients can be provided (which can be obtained by referring to ASME II-D), it can also be used in complex scenarios such as nuclear power and petrochemical.

[0044] The total bending moment calculation formula in step S2 can be directly embedded in the pressure vessel design calculation software, replacing the traditional Waters method or the empirical coefficient method.

[0045] In some embodiments, step S3 specifically includes: S31: Set the outer diameter of the flange neck 5 large end , flange neck 5 inner diameter , calculate the moment of inertia of flange neck 5: ; S32: Based on superimposed bending moments Calculate the deflection of flange 3: , in, Bending stiffness is a comprehensive reflection of the resistance of materials and geometric properties to bending deformation; It is the elastic modulus of the flange metal material at the design temperature, in MPa. When the temperature is high, it needs to be corrected. It can be found in the standard GB / T150.2-2024 or GB / T4732.2-2024.

[0046] The neck 5 of the high-neck flange is the core area that bears bending moment and deformation. Its length and cross-sectional shape directly affect the bending stiffness. The flange 6 may experience slight warping under extreme loads (such as large bending moment or high-temperature creep). However, within the pressure and temperature range specified in step S2, its contribution to the total deflection is much less than 5%. In addition, the flange is thick and rigid, so its deformation can be ignored. Therefore, step S3 only considers the moment of inertia of the flange neck, and does not include the moment of inertia of the flange (calculated based on the combined cross-section). The deflection is only reduced by about 3% to 4%, and the error is within the allowable range of the project (≤5%).

[0047] In some embodiments, step S4 specifically includes: S41: Determine the material and type of the gasket 7 according to the medium, temperature, and pressure.

[0048] S42: Get the material parameters of gasket 7: Check the equivalent elastic modulus of the gasket , allowable compressive stress of gasket .

[0049] S43: Calculate the theoretical allowable deformation of gasket 7: , Where, is the initial thickness of gasket 7.

[0050] In some embodiments, the equivalent elastic modulus of the gasket 7 in step S42 is , when using metal spiral wound gasket, it can be 3850MPa, when using non-metallic gasket, it can be 160MPa, The actual measured value given in the manufacturer's quality certificate may also be taken.

[0051] In some embodiments, the allowable compressive stress of the gasket 7 in step S42 is , when using metal spiral wound gasket, it can be 64MPa, when using non-metallic gasket, it can be 12MPa, The actual measured value given in the manufacturer's quality certificate may also be taken.

[0052] In some embodiments, step S5 specifically includes: Theoretical allowable deformation of gasket 7 Introducing the safety factor F, the allowable deformation of gasket 7 , if the deflection of flange 3 Smaller than the allowable deformation of the gasket , then the sealing check of the structure of the head 1 directly connected to the flange 3 is qualified, otherwise the height of the flange neck 5 or the thickness of the head 1 should be adjusted, and the above calculation should be repeated until the check is qualified.

[0053] In some embodiments, the safety factor F in step S5 is 2.0.

[0054] Example 2 The disclosed embodiments also provide a device for determining the sealing performance of a direct-connection structure between a head and a high-neck flange, comprising a processor and memory. Optionally, the device may also include a communication interface and a bus. The processor, communication interface, and memory may communicate with each other via the bus. The communication interface may be used for information transmission. The processor may invoke logic instructions stored in the memory to execute the method for determining the sealing performance of a direct-connection structure between a head and a high-neck flange described in the aforementioned embodiment.

[0055] In addition, the logic instructions in the above-mentioned memory can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product.

[0056] Memory, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as the program instructions / modules corresponding to the methods in the embodiments of the present disclosure. The processor executes the program instructions / modules stored in the memory to perform functional applications and data processing, thereby implementing the method for determining the sealing performance of the direct connection structure between the head and the high-neck flange in the above-mentioned embodiment.

[0057] The memory may include a program storage area and a data storage area. The program storage area may store an operating system and at least one application required for a function; the data storage area may store data generated based on the use of the terminal device. Furthermore, the memory may include high-speed random access memory and non-volatile memory.

[0058] An embodiment of the present disclosure provides a computer-readable storage medium storing computer-executable instructions, wherein the computer-executable instructions are configured to execute the above-mentioned method for determining the sealing performance of a direct connection structure between a head and a high-neck flange.

[0059] The aforementioned computer-readable storage medium may be a transient computer-readable storage medium or a non-transitory computer-readable storage medium.

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for determining the sealing performance of a direct connection structure between a head and a high-neck flange, characterized in that: The following steps are involved: The head and high-neck flange are regarded as elastic continuum, and the deformation coordination equation under the combined action of internal pressure, bolt preload and temperature load is established. The total bending moment is solved by solving the simultaneous equations of deformation coordination conditions at the connection between the head and the flange; Calculate the flange deflection based on the total bending moment and the flange neck section moment of inertia; Determine the theoretical allowable deformation based on the gasket material parameters and initial thickness; A safety factor is introduced to correct the allowable deformation of the gasket and compared with the flange deflection. If the flange deflection is less than the allowable deformation of the gasket, the sealing is judged to be qualified.

2. The method for determining the sealing performance of a direct connection structure between a head and a high-neck flange according to claim 1 is characterized in that: The total bending moment in step S2 The calculation formula is: ， in: is the flange bending moment caused by internal pressure, is the additional bending moment generated by the bolt preload, is the equivalent diameter of the head, is the curvature radius of the neutral layer of the head, is the thickness of the head, is the flange neck height, is the design internal pressure, is the Poisson's ratio of the material.

3. The method for determining the sealing performance of a direct connection structure between a head and a high-neck flange according to claim 2 is characterized in that: The flange deflection The calculation formula is as follows: ， in, is the elastic modulus of the flange metal material at the design temperature, is the flange neck section moment of inertia, and the calculation formula is: ， in, The outer diameter of the flange neck large end, is the inner diameter of the flange neck.

4. The method for determining the sealing performance of a direct connection structure between a head and a high-neck flange according to claim 1 is characterized in that: The theoretical allowable deformation of the gasket The calculation formula is: ， in, is the allowable compressive stress of the gasket, is the initial thickness of the gasket, is the equivalent elastic modulus of the gasket.

5. The method for determining the sealing performance of a direct connection structure between a head and a high-neck flange according to claim 4 is characterized in that: The equivalent elastic modulus of the gasket is selected according to the material: 3850 MPa for metal spiral wound gaskets and 160 MPa for non-metallic gaskets.

6. The method for determining the sealing performance of a direct connection structure between a head and a high-neck flange according to claim 4 is characterized in that: The allowable deformation of the modified gasket for: ， in, is the safety factor, which is 2.

7. A device for determining the sealing performance of a direct connection structure between a head and a high-neck flange, comprising a processor and a memory storing program instructions, characterized in that: The processor is configured to execute the method for determining the sealing performance of the direct connection structure between the head and the high-neck flange according to any one of claims 1 to 6 when running the program instructions.

8. A computer-readable storage medium, characterized in that A computer program is stored thereon, and when the program is executed by a processor, a method for determining the sealing performance of a direct connection structure between a head and a high-neck flange as described in any one of claims 1 to 6 above is implemented.

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