A minimum S index method for quantitative evaluation of sealing performance of pipe connection pairs

Abstract

This invention discloses a minimum S-index method for quantitatively evaluating the sealing performance of pipe connection pairs, belonging to the technical field of quantitative evaluation of pipe connection pair sealing performance. The method includes the following steps: S1, collecting redundant contact pressures of the sealing cone ring in the pipe connection pair under specific operating conditions; S2, defining the minimum S-index and deriving its calculation model; S3, solving for the path from any node on the inner diameter of the sealing cone ring to any node on the outer diameter, minimizing the value of the minimum S-index in S2; S4, quantitatively evaluating the sealing performance of the pipe connection pair based on the calculation results of S3. This invention, by defining and calculating the minimum S-index on the sealing surface, achieves efficient and quantitative evaluation of the sealing performance of a three-dimensional sealing cone ring under non-uniform contact pressure.

Description

Technical Field

[0001] This invention relates to the field of quantitative evaluation of the sealing performance of pipe connection pairs, and in particular to a minimum S-index method for quantitative evaluation of the sealing performance of pipe connection pairs. Background Technology

[0002] In aero-engines, hydraulic systems, and various complex mechanical equipment, pipeline connections are key components for transporting fluid media, and their sealing reliability directly affects the operational safety, efficiency, and service life of the entire system. For a long time, methods for evaluating sealing performance in this field have primarily relied on macroscopic parameters such as average contact pressure, sealing bandwidth, and maximum contact pressure, or on approximate analysis using simplified leakage models based on classical fluid mechanics. However, with the deepening research into the microscopic mechanisms of interfacial sealing, current technological development has shifted from macroscopic flow field analysis to a more refined characterization of the microscopic contact behavior of the sealing interface.

[0003] However, most existing technologies are based on the ideal assumption that the contact pressure is uniformly distributed circumferentially or is axisymmetric. Therefore, existing technologies are insufficient in evaluating the sealing performance of pipeline connection pairs, in terms of characterizing the sealing performance under non-uniform pressure distribution, adaptability to complex sealing cone rings, and engineering practical efficiency. Summary of the Invention

[0004] The purpose of this invention is to provide a minimum S-index method for quantitatively evaluating the sealing performance of pipeline connection pairs. By defining and calculating the minimum S-index on the decryption cover, an efficient and quantitative evaluation of the sealing performance of a three-dimensional sealing cone ring under non-uniform contact pressure is achieved.

[0005] To achieve the above objectives, the present invention provides a minimum S-index method for quantitatively evaluating the sealing performance of pipeline connection pairs, comprising the following steps: S1, collecting redundant contact pressure of the sealing cone ring in the pipeline connection pair under specific working conditions; S2. Define the minimum S-exponent and derive the calculation model for the minimum S-exponent; S3. Solve for the path from any node on the inner diameter of the sealing cone ring to any node on the outer diameter, so that the value of the minimum S-exponent in S2 is minimized. S4. Quantitatively evaluate the sealing performance of the pipeline connection pair based on the calculation results of S3.

[0006] Preferably, the pipe connection includes a flared pipe, a pipe fitting, an outer nut, and a flat nozzle. The flared end of the flared pipe is connected to the pipe fitting, and the flat nozzle is fitted onto one end of the flared end of the flared pipe. One end of the outer nut is fitted onto the outside of the pipe fitting, and the other end is fitted onto the outside of the flat nozzle.

[0007] Preferably, the flared end of the flared pipe and the connection point of the pipe fitting form a sealing cone ring structure, and the maximum outer diameter of the flat pipe nozzle is the same as the maximum outer diameter of the part of the fitting pipe located inside the outer nut.

[0008] Preferably, the process of S1 is as follows: S11. Obtain discrete contact pressure distribution data of the sealing cone ring under specific working conditions. ,in This indicates the axial projection position of any point on the sealing cone ring in the installation direction of the pipeline connection pair. Indicates the circumferential angular position of the selected point; S12. Determine the critical contact pressure required to achieve zero leakage based on the microstructure of the sealing cone ring. ; S13. Determine the redundant contact pressure of the sealing cone ring based on the discrete contact pressure distribution data and the critical contact pressure. The calculation process is as follows: .

[0009] Preferably, the process of S2 is as follows: S21. Select the weakest sealing path on the sealing cone ring sealing surface. In the sealing path Choose any point in the array, and the parameter form of that point is: Calculate along the sealing path arc length of infinitesimal element The process is as follows: ; in , , Indicates the half-apex angle of the sealing cone ring. express The first derivative, and These represent the inner and outer diameters of the sealing cone ring, respectively. S22, via sealing path arc length of infinitesimal element The minimum S-exponent is defined as follows: ; ; ; in Represents the minimum S-exponent. This indicates the weakest sealing path on the sealing cone ring surface. This represents the set of all possible connected paths from the inner diameter to the outer diameter of the sealing cone ring. This represents the cumulative arc length starting from the path's origin. express First-order differentiability, Indicates continuity; S23. Discretize the minimum S-exponent, select a path consisting of k nodes on the sealing cone ring, and calculate the increment of the minimum S-exponent. The process is as follows: ; ; in Indicates the path Redundant contact pressure at points , express Redundant contact pressure at points Indicates adjacent positions and The distance between them; S24. All of the paths The cumulative value is denoted as the total S-index of the path. The smallest value The corresponding path is the weakest point on the sealing cone ring that is most prone to leakage, and it is considered as a discrete calculation model with the minimum S-exponent. The calculation process is as follows: .

[0010] Preferably, the process of S3 is as follows: S31. Construct a spatial contact pressure distribution matrix based on the redundant contact pressure of each node in the discrete finite element mesh of the sealing cone ring, and initialize it. Set all nodes on the inner diameter of the sealing cone ring as the starting point set and all nodes on the outer diameter as the ending point set. S32. Establish weighted adjacency moments through the connection relationships between adjacent nodes, and model the connection relationships between adjacent nodes as weighted edges through the leaked direction weight mechanism; S33. Using the nodes in the starting set as the starting nodes, reach the nodes in the ending set through the improved Dijkstra path search to obtain all paths. The optimal path is obtained by comparing the number of nodes in each path. S34. Starting from the endpoint of the optimal path, trace backwards to the starting node to construct a complete sequence of nodes along the weakest leak path. Treat the weight of each edge on the optimal path as a... The minimum S-index value of the sealing cone ring is obtained by substituting it into the calculation model of the minimum S-index.

[0011] Preferably, the leakage direction weighting mechanism in S32 is as follows: the node is given the highest priority for moving along the direction of the sealing cone ring generatrix, followed by diagonal movement, and the lowest priority for circumferential horizontal movement; at the same time, a path length penalty coefficient is added to each edge to ensure that when multiple paths calculate the same total S index, the path that passes through fewer nodes and is more direct is selected first.

[0012] Preferably, the process of S33 is as follows: S331. Take one of the nodes in the starting set as the starting node; S332. Starting from the starting node, traverse all adjacent nodes connected to it, calculate the path distance value from the current node to each adjacent node, select the adjacent node with the smallest path distance value as the next current node, update the cumulative distance value and path information. If there are the same path distance values ​​within the tolerance range, further compare the total number of nodes traversed by the path corresponding to the same path distance value, select the path with fewer nodes as the next current node, and update the cumulative distance value and path information. S333. A path is obtained until the endpoint node in the endpoint set is reached; S334. Return to S331 and select a new starting node. Continue traversing all starting nodes until the total number of nodes in all paths is reached. The path with the fewest total nodes is the optimal path.

[0013] Preferably, the process of S4 is as follows: S41. Obtain the minimum S-index value for different cycles under specific working conditions through the process of S1-S3. S42. By comparing the minimum S-index value under different cycles, the sealing performance of the sealing cone ring is quantitatively evaluated, and the quantitative evaluation of the sealing performance of the pipeline connection pair is completed.

[0014] Preferably, the larger the minimum S-index value, the higher the sealing reliability; the smaller the minimum S-index value, the greater the risk of leakage.

[0015] Therefore, this invention employs the aforementioned minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs. By proposing the "minimum S-index" as a core evaluation index, it effectively addresses the shortcomings of existing sealing performance evaluation methods in terms of non-uniform contact pressure, complex geometric interfaces, and engineering practicality. It can accurately identify and quantify the weakest leakage path on the sealing cone ring, thereby achieving a direct and sensitive evaluation of sealing reliability. It is particularly suitable for harsh operating conditions where vibration wear, assembly deviations, and other factors lead to dynamic changes in contact pressure distribution.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is an overall flowchart of the minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to the present invention. Figure 2 This is a structural diagram of a pipe connection pair according to the minimum S-index method for quantitative evaluation of the sealing performance of a pipe connection pair according to the present invention. Figure 3 This is a schematic diagram of the assembly deviation in the minimum S-index method for quantitative evaluation of the sealing performance of a pipeline connection pair according to the present invention. Figure 4 This is a non-uniform contact pressure distribution diagram in the minimum S-index method for quantitative evaluation of the sealing performance of a pipeline connection pair according to the present invention. Figure 5 This is a schematic diagram of discrete contact pressure distribution data on a sealing cone ring in the minimum S-index method for quantitative evaluation of the sealing performance of a pipeline connection pair according to the present invention. Figure 6 This is a diagram illustrating the S-index in the minimum S-index method for quantitatively evaluating the sealing performance of a pipe connection pair according to the present invention. Figure 6 (a) shows the circumferential uniform distribution of contact pressure on the sealing surface; Figure 6 (b) shows the integral of the S-index under the sealed path; Figure 7 This is a schematic diagram of the arc length of a micro-element in the minimum S-index method for quantitative evaluation of the sealing performance of a pipeline connection pair according to the present invention. Figure 8 This is a flowchart of S3 in the minimum S-index method for quantitative evaluation of the sealing performance of a pipeline connection pair according to the present invention. Figure 9 This is a graph showing the quantitative evaluation results of the sealing performance of an embodiment of the minimum S-index method for quantitative evaluation of the sealing performance of a pipeline connection pair according to the present invention. Figure 9 Figure (a) shows the variation of contact pressure distribution under vibration and wear with the wear cycle in the embodiment. Figure 9 Figure (b) shows the variation of the minimum S-index value with the period in the example; Figure labels; 1. Flared pipe; 2. Pipe fitting; 3. Outer nut; 4. Flat pipe nozzle; 5. Sealing cone ring. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Specific model specifications need to be selected and determined according to the actual specifications of the device, etc. The specific selection calculation method adopts existing technology in the art, and therefore will not be described in detail.

[0019] Example Existing technologies still have significant limitations in evaluating the sealing performance of pipeline connection joints. Most existing methods are based on the ideal assumption that the contact pressure is uniformly distributed circumferentially or axisymmetric. However, under complex loads (such as vibration wear and assembly deviations), the sealing interface often exhibits a highly non-uniform, asymmetric, and dynamically evolving pressure distribution over time. Traditional evaluation indicators based on average values ​​or single cross-sections are difficult to capture the key impact of local weak areas on the overall sealing performance.

[0020] Seal failure typically begins in the localized area with the lowest contact pressure or the shortest effective sealing path. However, existing holistic evaluation parameters, such as average contact pressure and critical weighted area, lack the ability to identify the weakest sealing path on the sealing surface, resulting in insufficient sensitivity and accuracy in predicting progressive seal degradation caused by vibration and wear.

[0021] The sealing interface of the flared pipe connection is a three-dimensional conical ring with a complex contact pressure distribution. Existing leakage models are mostly developed for regular planes or toroidal surfaces, which are poorly adapted to such complex geometries and the resulting non-uniform contact conditions. The model parameters are also difficult to update and correct in real time during dynamic wear.

[0022] In practical engineering applications, while some high-precision multi-scale computational fluid dynamics models based on real surface morphology can provide detailed reconstructions, their computational costs are high, making it difficult to meet the needs of rapid evaluation and design iteration in actual engineering. On the other hand, oversimplified models often sacrifice the ability to capture key physical phenomena such as pressure distribution evolution and wear morphology changes, resulting in a common contradiction between engineering applicability and computational efficiency.

[0023] like Figures 1-9 As shown, this invention provides a minimum S-index method for quantitatively evaluating the sealing performance of pipe connection pairs, comprising the following steps: S1. Collect the redundant contact pressure of the sealing cone ring 5 in the pipeline connection pair under specific working conditions. Specific working conditions include, but are not limited to, assembly deviation and vibration wear. In this embodiment, vibration wear is selected as the specific working condition. S11. Obtain discrete contact pressure distribution data of sealing cone ring 5 under a certain vibration and wear cycle. ,in This indicates the axial projection position of any point on the sealing cone ring 5 in the installation direction of the pipeline connection pair. Indicates the circumferential angular position of the selected point; S12. Determine the critical contact pressure required to achieve zero leakage based on the microstructure (such as roughness and porosity) of the sealing cone ring 5. ; S13. Determine the redundant contact pressure of the sealing cone ring 5 based on the discrete contact pressure distribution data and the critical contact pressure. The calculation process is as follows: .

[0024] Areas below the critical contact pressure are considered ineffective sealing areas (redundant contact pressure is 0).

[0025] The S-index represents redundant contact pressure. The integral of the effective sealing path can comprehensively evaluate the sealing performance of a sealing path. A larger S-index indicates better sealing performance and a lower likelihood of leakage; conversely, a smaller S-index indicates the opposite. During initial pre-tightening, the contact pressure on the sealing surface is evenly distributed circumferentially, such as... Figure 6 As shown in (a). One of them extends from the inner diameter of the sealing cone ring 5. To outer diameter The integral of the S-exponent under the sealed path is as follows Figure 6 As shown in (b), the calculation formula is as follows: ; However, the S-index method described above can only be used to evaluate sealing performance when the circumferential contact pressure distribution is uniform. When dealing with non-uniform circumferential pressure distribution, calculations are performed based on the average circumferential contact pressure distribution and the average effective sealing path, which will lead to a large error in the evaluation of sealing performance.

[0026] S2. Define the minimum S-exponent and derive the calculation model for the minimum S-exponent; S21. Select the weakest sealing path on the sealing surface of sealing cone ring 5. In the sealing path Choose any point in the array, and the parameter form of that point is: Calculate along the sealing path arc length of infinitesimal element The process is as follows: ; in , , This indicates the half-apex angle of the sealing cone ring. express The first derivative, and These represent the inner and outer diameters of the sealing cone ring 5, respectively. S22, via sealing path arc length of infinitesimal element The minimum S-exponent is defined as follows: ; ; ; in Represents the minimum S-exponent. This indicates the weakest sealing path on the sealing surface of sealing cone ring 5. This represents the set of all possible connected paths from the inner diameter to the outer diameter of the sealing cone ring. This represents the cumulative arc length starting from the path's origin. express First-order differentiability, Indicates continuity; S23. Discretize the minimum S-exponent. Select a path consisting of k nodes on the sealing cone ring 5 and calculate the increment of the minimum S-exponent. The process is as follows: ; ; ; in Indicates the path Redundant contact pressure at points , express Redundant contact pressure at points Indicates adjacent positions and The distance between them; S24. All of the paths The cumulative value is denoted as the total S-index of the path. The smallest value The corresponding path is the weakest sealing path on the sealing cone ring 5, which is most prone to leakage. It is considered as a discrete calculation model with the minimum S-exponent. The calculation process is as follows: .

[0027] S3. Solve for the path from any node on the inner diameter of the sealing cone ring 5 to any node on the outer diameter, so that the value of the minimum S exponent in S2 is minimized. On a grid of an arbitrary sealing cone ring 5, each grid node corresponds to a contact pressure value. The goal is to find a continuous path from an arbitrary node on the inner diameter of the sealing surface (the location where leakage begins) to an arbitrary node on the outer diameter of the sealing surface (the location where leakage ends), such that this path... Minimum.

[0028] S31. Construct a spatial contact pressure distribution matrix based on the redundant contact pressure of each node in the discrete finite element mesh of the sealing cone ring 5, and initialize it. Set all nodes on the inner diameter of the sealing cone ring 5 as the starting point set and all nodes on the outer diameter as the ending point set. During the data preparation phase, the algorithm is based on a discrete finite element mesh of the sealing cone ring 5, with each mesh node corresponding to a contact pressure value. The goal is to find a continuous path from any node on the inner diameter of the sealing surface (starting position) to any node on the outer diameter of the sealing surface (ending position) that minimizes the total S-exponent of the path. The core input data for the algorithm includes the spatial contact pressure distribution matrix of the sealing surface nodes.

[0029] S32. Establish weighted adjacency moments through the connection relationships between adjacent nodes, and model the connection relationships between adjacent nodes as weighted edges through the leaked direction weight mechanism; In the weighted adjacency matrix establishment phase, the algorithm models the connection relationships between adjacent nodes as weighted edges. The weight of each edge reflects the contribution of that line segment to the leakage resistance, and its calculation comprehensively considers the geometric distance between nodes and the average effective redundant pressure.

[0030] To reflect the physical law that leakage develops along the direction of least resistance, a leakage direction weighting mechanism is introduced: the highest priority is given to moving nodes along the generatrix of the sealing cone ring 5, followed by diagonal movement, and the lowest priority is given to circumferential horizontal movement; at the same time, a path length penalty coefficient is added to each edge to ensure that when multiple paths calculate the same total S index, the path with fewer nodes and more directness is selected first, thus ensuring the uniqueness and rationality of the result.

[0031] S33. Using the nodes in the starting set as the starting nodes, reach the nodes in the ending set through the improved Dijkstra path search to obtain all paths. The optimal path is obtained by comparing the number of nodes in each path. In the main loop, the algorithm iterates through all nodes, selecting the node with the smallest current cumulative distance value from the unvisited nodes as the current processing node. For each neighboring node of the current node, the algorithm calculates the cumulative distance value of a new path from the current node to that neighbor. If this new value is less than the previously recorded distance value of the neighboring node, its distance value and path information are updated; if the new and old distance values ​​are equal within the tolerance range, the total number of nodes traversed by the two paths is further compared, and the path with fewer nodes is selected for updating. This dual comparison mechanism is the key to the improvement of this algorithm.

[0032] S331. Take one of the nodes in the starting set as the starting node; S332. Starting from the starting node, traverse all adjacent nodes connected to it, calculate the path distance value from the current node to each adjacent node, select the adjacent node with the smallest path distance value as the next current node, update the cumulative distance value and path information. If there are the same path distance values ​​within the tolerance range, further compare the total number of nodes traversed by the path corresponding to the same path distance value, select the path with fewer nodes as the next current node, and update the cumulative distance value and path information. S333. A path is obtained until the endpoint node in the endpoint set is reached; S334, Return to S341 and select a new starting node. Continue traversing all starting nodes until the total number of nodes in all paths is reached. The path with the fewest total nodes is the optimal path.

[0033] S34. Starting from the endpoint of the optimal path, trace backwards to the starting node to construct a complete sequence of nodes along the weakest leak path. Treat the weight of each edge on the optimal path as a... Substituting the minimum S-index into the calculation model, we obtain the minimum S-index value of the sealing cone ring 5.

[0034] Minimum S-index of sealing surface Calculation Phase. After the algorithm has traversed all nodes, the information for all possible paths has been determined. By backtracking the predecessor node array, starting from the optimal endpoint (i.e., the node with the smallest cumulative distance value on the outer diameter), and tracing back to the starting point, the complete sequence of nodes for the weakest leakage path can be constructed. The minimum S-exponential value of the sealing surface is calculated by summing the weights of all edges on this path.

[0035] S4. Quantitatively evaluate the sealing performance of the pipeline connection pair based on the calculation results of S3.

[0036] Obtain the minimum S-exponent Then, the sealing performance can be quantitatively evaluated. The value directly reflects the sealing capability of the weakest sealing path at the current sealing interface. The larger the value, the higher the sealing reliability; the smaller the value, the greater the risk of leakage.

[0037] S41. Obtain the minimum S-index value for different cycles under specific working conditions through the process of S1-S3. S42. By comparing the minimum S-index value under different cycles, the sealing performance of the sealing cone ring 5 is quantitatively evaluated, and the quantitative evaluation of the sealing performance of the pipeline connection pair is completed.

[0038] The larger the minimum S-index value, the higher the sealing reliability; the smaller the minimum S-index value, the greater the risk of leakage.

[0039] The pipe connection assembly includes a flared pipe 1, a pipe fitting 2, an outer nut 3, and a flat nozzle 4. The flared end of the flared pipe is connected to the pipe fitting 2. The flat nozzle is fitted onto one end of the flared end of the flared pipe 1. One end of the outer nut 3 is fitted onto the outside of the pipe fitting 2, and the other end is fitted onto the outside of the flat nozzle 4.

[0040] The flared end of the flared tube 1 connects with the pipe fitting 2 to form a sealing cone ring 5 structure. The maximum outer diameter of the flat pipe nozzle 4 is the same as the maximum outer diameter of the part of the fitting tube located inside the outer nut 3.

[0041] In this embodiment, the change of contact pressure distribution with the wear cycle under a certain vibration and wear condition is as follows: Figure 9 As shown in (a), the red line represents the weakest sealing path under the minimum S-index. It can be seen that the non-uniform contact pressure caused by vibration wear also causes the minimum S-index path to no longer extend directly from the inner diameter to the outer diameter of the sealing cone ring 5, but instead to bend at an angle. Simultaneously, the value of the minimum S-index decreases significantly with increasing period, as shown... Figure 9 As shown in Figure (b), it is clearly revealed that after long-term vibration and wear, the effective sealing ability of the sealing surface of the pipeline connection sub-seal is severely degraded, and the sealing performance deteriorates significantly.

[0042] Therefore, this invention employs a minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs. By proposing the "minimum S-index" as a core evaluation index, it effectively addresses the shortcomings of existing sealing performance evaluation methods in terms of non-uniform contact pressure, complex geometric interfaces, and engineering practicality. It can accurately identify and quantify the weakest leakage path on the sealing cone ring 5, thereby achieving a direct and sensitive evaluation of sealing reliability. This method is particularly suitable for harsh operating conditions where vibration wear, assembly deviations, and other factors lead to dynamic changes in contact pressure distribution.

[0043] Compared with traditional methods that rely on macroscopic average parameters or high-cost multi-scale simulation, this method significantly reduces computational costs through efficient algorithms while ensuring evaluation accuracy. It provides a powerful quantitative tool for rapid design iteration and state prediction in engineering, and greatly improves the scientific and reliability assurance level of pipeline connection sealing design in key fields such as aero-engines and hydraulic systems.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A minimum S-index method for quantitatively evaluating the sealing performance of pipe connection pairs, characterized in that, Includes the following steps: S1, collects redundant contact pressure of the sealing cone ring in the pipeline connection pair under specific working conditions, including assembly deviation and vibration wear; S2. Define the minimum S-exponent and derive the calculation model for the minimum S-exponent; S3. Solve for the path from any node on the inner diameter of the sealing cone ring to any node on the outer diameter, so that the value of the minimum S-exponent in S2 is minimized. S4. Quantitatively evaluate the sealing performance of the pipeline connection pair based on the calculation results of S3.

2. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 1, characterized in that: The pipe connection assembly includes a flared pipe, a pipe fitting, an outer nut, and a flat nozzle. The flared end of the flared pipe is connected to the pipe fitting, and the flat nozzle is fitted onto one end of the flared end of the flared pipe. One end of the outer nut is fitted onto the outside of the pipe fitting, and the other end is fitted onto the outside of the flat nozzle.

3. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 2, characterized in that: The flared end of the flared pipe connects to the pipe fitting to form a sealing cone ring structure. The maximum outer diameter of the flat pipe nozzle is the same as the maximum outer diameter of the part of the fitting pipe located inside the outer nut.

4. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 3, characterized in that, The process of S1 is as follows: S11. Obtain discrete contact pressure distribution data of the sealing cone ring under specific working conditions. ,in This indicates the axial projection position of any point on the sealing cone ring in the installation direction of the pipeline connection pair. Indicates the circumferential angular position of the selected point; S12. Determine the critical contact pressure required to achieve zero leakage based on the microstructure of the sealing cone ring. ; S13. Determine the redundant contact pressure of the sealing cone ring based on the discrete contact pressure distribution data and the critical contact pressure. The calculation process is as follows: 。 5. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 4, characterized in that, The process of S2 is as follows: S21. Select the weakest sealing path on the sealing cone ring sealing surface. In the sealing path Choose any point in the array, and the parameter form of that point is: Calculate along the sealing path arc length of infinitesimal element The process is as follows: ； in , , Indicates the half-apex angle of the sealing cone ring. express The first derivative, and These represent the inner and outer diameters of the sealing cone ring, respectively. S22, via sealing path arc length of infinitesimal element The minimum S-exponent is defined as follows: ； ； ； in Represents the minimum S-exponent. This indicates the weakest sealing path on the sealing cone ring surface. This represents the set of all possible connected paths from the inner diameter to the outer diameter of the sealing cone ring. This represents the cumulative arc length starting from the path's origin. express First-order differentiability, Indicates continuity; S23. Discretize the minimum S-exponent, select a path consisting of k nodes on the sealing cone ring, and calculate the increment of the minimum S-exponent. The process is as follows: ； ； in Indicates the path Redundant contact pressure at points , express Redundant contact pressure at points Indicates adjacent positions and The distance between them; S24. All of the paths The cumulative value is denoted as the total S-index of the path. The smallest value The corresponding path is the weakest point on the sealing cone ring that is most prone to leakage, and it is considered as a discrete calculation model with the minimum S-exponent. The calculation process is as follows: 。 6. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 5, characterized in that, The process of S3 is as follows: S31. Construct a spatial contact pressure distribution matrix based on the redundant contact pressure of each node in the discrete finite element mesh of the sealing cone ring, and initialize it. Set all nodes on the inner diameter of the sealing cone ring as the starting point set and all nodes on the outer diameter as the ending point set. S32. Establish weighted adjacency moments through the connection relationships between adjacent nodes, and model the connection relationships between adjacent nodes as weighted edges through the leaked direction weight mechanism; S33. Using the nodes in the starting set as the starting nodes, reach the nodes in the ending set through the improved Dijkstra path search to obtain all paths. The optimal path is obtained by comparing the number of nodes in each path. S34. Starting from the endpoint of the optimal path, trace backwards to the starting node to construct a complete sequence of nodes along the weakest leak path. Treat the weight of each edge on the optimal path as a... The minimum S-index value of the sealing cone ring is obtained by substituting it into the calculation model of the minimum S-index.

7. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 6, characterized in that, The leakage direction weighting mechanism in S32 is as follows: the highest priority is given to moving nodes along the direction of the sealing cone ring generatrix, followed by diagonal movement, and the lowest priority is given to circumferential horizontal movement; at the same time, a path length penalty coefficient is added to each edge to ensure that when multiple paths calculate the same total S index, the path that passes through fewer nodes and is more direct is selected first.

8. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 7, characterized in that, The process of S33 is as follows: S331. Take one of the nodes in the starting set as the starting node; S332. Starting from the starting node, traverse all adjacent nodes connected to it, calculate the path distance value from the current node to each adjacent node, select the adjacent node with the smallest path distance value as the next current node, update the cumulative distance value and path information. If there are the same path distance values ​​within the tolerance range, further compare the total number of nodes traversed by the path corresponding to the same path distance value, select the path with fewer nodes as the next current node, and update the cumulative distance value and path information. S333. A path is obtained until the endpoint node in the endpoint set is reached; S334. Return to S331 and select a new starting node. Continue traversing all starting nodes until the total number of nodes in all paths is reached. The path with the fewest total nodes is the optimal path.

9. The minimum S-index method for quantitative evaluation of the sealing performance of pipeline connection pairs according to claim 8, characterized in that, The process of S4 is as follows: S41. Obtain the minimum S-index value for different cycles under specific working conditions through the process of S1-S3. S42. By comparing the minimum S-index value under different cycles, the sealing performance of the sealing cone ring is quantitatively evaluated, and the quantitative evaluation of the sealing performance of the pipeline connection pair is completed.

10. The minimum S-index method for quantitative evaluation of the sealing performance of a pipeline connection pair according to claim 9, characterized in that: The larger the minimum S-index value, the higher the sealing reliability; the smaller the minimum S-index value, the greater the risk of leakage.

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