Method for evaluating fastening force of pipeline flange bolt group

Abstract

The invention specifically relates to a method for evaluating the fastening force of a pipeline flange bolt group, and the method comprises the steps: data collection: obtaining the related information of a flange and a bolt group, and the related information comprises the pre-tightening force information, the bolt stress information and the flange deformation information; data processing: analyzing the information to respectively obtain a pre-tightening force difference coefficient, a stress coefficient and a flange deformation coefficient, and performing comprehensive analysis to obtain a fastening force evaluation coefficient; performing data evaluation: performing fastening force grade evaluation on the fastening force of the pipeline flange bolt group according to the fastening force evaluation coefficient; and performing result early warning. According to the method, multiple factors such as the pre-tightening force information, the bolt stress information and the flange deformation information are comprehensively considered, and compared with a traditional single-factor evaluation method, the actual fastening state of the pipeline flange bolt set can be reflected more comprehensively, so that the evaluation result is more accurate and reliable; the operation safety and reliability of the pipeline system can be effectively improved, and the problem of inaccurate evaluation caused by neglecting some key factors is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline engineering, and in particular to a method for evaluating the tightening force of a pipeline flange bolt group. Background Art

[0002] Flange connections are a common connection method in pipeline systems, and accurate assessment of the tightening force of their bolt groups is crucial. Insufficient tightening force can lead to flange seal failure, causing media leakage, resulting in safety accidents and environmental pollution. Excessive tightening force can overload the bolts, causing plastic deformation or even fracture, also affecting the normal operation of the pipeline system.

[0003] Currently, traditional methods for assessing the tightening force of pipeline flange bolt assemblies are relatively simplistic, often considering only a single factor, such as preload or bolt stress. These methods fail to fully reflect the actual tightening state of the bolt assembly. For example, relying solely on preload may overlook abnormal bolt stress caused by factors such as vibration and medium pressure fluctuations during operation. Focusing solely on bolt stress also makes it difficult to consider the impact of flange deformation on tightening force. This one-sided assessment approach poses significant safety risks during pipeline system operation and fails to meet the stringent safety and reliability requirements of modern industry.

[0004] Therefore, a comprehensive and accurate method for evaluating the tightening force of pipeline flange bolt groups is urgently needed. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems and to propose a method for evaluating the tightening force of a pipeline flange bolt group.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for evaluating the tightening force of a pipeline flange bolt group, comprising:

[0008] Data collection: Obtain relevant information about flanges and bolt groups, including preload information, bolt stress information, and flange deformation information;

[0009] Data processing: After analyzing the information, the preload difference coefficient, stress coefficient and flange deformation coefficient are obtained respectively, and the tightening force evaluation coefficient is obtained after comprehensive analysis;

[0010] Data evaluation: Evaluate the tightening force level of the pipeline flange bolt group based on the tightening force evaluation coefficient;

[0011] Result warning: Carry out corresponding warning processing based on the tightening force level.

[0012] Preferably, the data collection specifically includes:

[0013] Bolt specifications, including nominal diameter, thread pitch, and material properties;

[0014] Flange related parameters, including flange type, size, and material properties;

[0015] The elongation of the bolt is measured by strain gauges;

[0016] Information related to piping vibration;

[0017] Gasket related information;

[0018] Flange image information.

[0019] Preferably, the process of obtaining the preload force difference coefficient includes:

[0020] Obtain the design preload based on the medium pressure in the pipeline, flange sealing requirements, and the number of bolts;

[0021] According to Hooke's law, within the elastic range, the elongation of a bolt is proportional to the tensile force it receives. The elongation of each bolt in operation is obtained using strain gauges. Assuming that each bolt is uniformly stressed, the axial forces of each bolt are accumulated to obtain the combined axial force.

[0022] After calculating the difference between the designed preload force and the comprehensive axial force, the absolute value is taken to obtain the preload deviation value;

[0023] Obtain the elongation of each bolt, preset an allowable range for the bolt elongation, compare the elongation of each bolt with the allowable range, and record the elongation of the bolt that is not within the allowable range as an abnormal elongation;

[0024] Arrange the abnormal elongations in descending order according to their values, and take the three largest abnormal elongations;

[0025] Mark the bolts corresponding to the three largest abnormal elongations and record them as marked bolts;

[0026] Connect the three marked bolts in a straight line to obtain a triangular shape. Calculate the area of the triangular shape and record it as the bolt position difference.

[0027] The preload force difference coefficient is obtained by comprehensive analysis of the preload deviation value and the bolt position difference value.

[0028] Preferably, the process of obtaining the stress coefficient includes:

[0029] The tensile stress of each bolt is obtained based on the axial force of each bolt and its minor diameter cross-sectional area;

[0030] Preset the standard tensile stress and compare the tensile stress of each bolt with the standard tensile stress. If the tensile stress of the bolt exceeds the standard tensile stress, the tensile stress is recorded as abnormal tensile stress, and the bolt corresponding to the abnormal tensile stress is recorded as an abnormal tensile bolt;

[0031] Obtain the number of bolts with abnormal tension, and divide the number of bolts with abnormal tension by the total number of bolts to obtain the stress abnormality ratio;

[0032] Obtain the positions of the bolts with different tensions, and draw a circle with any bolt with different tensions as the center and a preset radius. Obtain the number of bolts with different tensions within the circle and record it as the concentrated number.

[0033] Taking each of the different-tension bolts as the center of the circle, and following the above steps, obtain the concentrated number of each different-tension bolt within the circular range corresponding to the bolt;

[0034] Arrange the concentrated quantities in descending order according to their numerical values, extract the largest concentrated quantity, and divide the largest concentrated quantity by the number of abnormally pulled bolts to obtain the concentration ratio;

[0035] The preliminary coefficient is obtained by comprehensively analyzing the stress anomaly ratio and concentration ratio;

[0036] Perform pipeline vibration analysis on both sides of the pipelines fixed by the flange bolt group to obtain the vibration deviation coefficient;

[0037] The stress coefficient is obtained by comprehensively processing the preliminary coefficient and the vibration deviation coefficient.

[0038] Preferably, the process of obtaining the flange deformation coefficient includes:

[0039] Obtaining image information of the flange, and after preprocessing the image, dividing the flange into regions to obtain flange sub-regions with the same area;

[0040] Perform feature extraction on each flange sub-region, extract features related to wear and corrosion, and mark the extracted features as damaged areas and corroded areas respectively;

[0041] Calculate the number of pixels in the damaged and corroded areas of each flange sub-region, and convert the number of pixels in the damaged and corroded areas of each flange sub-region into actual areas based on the image resolution to obtain the damaged and corroded areas of each flange sub-region;

[0042] Obtain the overlapping parts of the damaged area and the corroded area of each flange sub-area in turn, as well as the area of the overlapping parts, which are recorded as the overlapping area; accumulate the overlapping areas of each flange sub-area to obtain the total overlapping area;

[0043] Obtain the contours of the damaged area and the corroded area in each flange area, and arrange marking points along the contours of the damaged area and the corroded area in sequence;

[0044] Connect any two marked points on the outline of the damaged area with a straight line, record the straight line as the damaged line, sort the obtained damaged lines in descending order according to their numerical values, and extract the largest damaged line; obtain the largest damaged line in each flange sub-area in turn;

[0045] The maximum damage line in each flange area is accumulated to obtain the damage span value;

[0046] Following the above process of analyzing the damaged area to obtain the damage span value, the corrosion area in each flange sub-area is analyzed to obtain the corrosion span value;

[0047] The corrosion value is obtained by multiplying the damage span value and the corrosion span value;

[0048] Analyze the bolts in the flange image information to obtain the imbalance value between the flange and the bolts;

[0049] The flange deformation coefficient is obtained by comprehensive analysis of the total overlapping area, corrosion value and imbalance value.

[0050] Preferably, the tightening force evaluation coefficient is obtained by comprehensively analyzing the preload difference coefficient, the stress coefficient and the flange deformation coefficient, specifically including:

[0051] After normalizing the preload difference coefficient, stress coefficient, and flange deformation coefficient, the preload difference coefficient and stress coefficient are used as two sides of a triangle, respectively. The angles of the two sides are preset to be within 40 degrees. The remaining side is connected to form a complete triangle. The flange deformation coefficient is used as the height of the triangle to construct a triangular pyramid model. The area of the triangular pyramid model is calculated and recorded as the tightening force evaluation coefficient.

[0052] Preferably, the tightening force level assessment of the pipeline flange bolt assembly includes:

[0053] Three groups of threshold value ranges are preset, each group of threshold value ranges corresponds to a tightening force level, and the tightening force evaluation coefficient is matched with the three groups of threshold value ranges to obtain the tightening force level corresponding to the tightening force evaluation coefficient, where the tightening force level includes unqualified, qualified, and excellent.

[0054] Preferably, the corresponding early warning processing based on the tightening force level includes:

[0055] When the tightening force level is unqualified: the bolt group is marked and the marked bolt group information is sent to the smart terminal of the relevant maintenance personnel. The maintenance personnel use accurate tools to retighten according to the correct torque requirements.

[0056] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0057] 1. By comprehensively considering multiple factors such as preload information, bolt stress information and flange deformation information, the present invention can more comprehensively reflect the actual tightening status of the pipeline flange bolt group compared to the traditional single-factor evaluation method, making the evaluation results more accurate and reliable, effectively improving the safety and reliability of pipeline system operation, and avoiding inaccurate evaluation problems caused by ignoring certain key factors.

[0058] 2. The present invention performs corresponding early warning processing according to the tightening force level. When the tightening force level is unqualified, the information can be sent to maintenance personnel in a timely manner so that measures can be taken quickly to repair it. When the tightening force level is qualified or excellent, potential problems can be discovered in a timely manner through recording and monitoring, providing protection for the long-term stable operation of the pipeline system. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Further details, features and advantages of the present application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0060] Figure 1 is a flow chart of the present invention; DETAILED DESCRIPTION

[0061] Several embodiments of the present application will be described in more detail below with reference to the accompanying drawings so that those skilled in the art can implement the present application. The present application can be embodied in many different forms and for many different purposes and should not be limited to the embodiments described herein. These embodiments are provided to make the present application comprehensive and complete and to fully convey the scope of the present application to those skilled in the art. The embodiments do not limit the present application.

[0062] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the relevant art and / or the context of this specification, and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0063] See also Figure 1 As shown, the present invention provides a technical solution:

[0064] A method for evaluating the tightening force of a pipeline flange bolt group, comprising:

[0065] Data collection: Obtain relevant information about flanges and bolt groups, including preload information, bolt stress information, and flange deformation information;

[0066] Data collection specifically includes:

[0067] Bolt specifications, including nominal diameter, thread pitch, and material properties;

[0068] Flange related parameters, including flange type, size, and material properties;

[0069] The elongation of the bolt is measured by strain gauges;

[0070] Information related to piping vibration;

[0071] Gasket related information;

[0072] Flange image information;

[0073] Data processing: After analyzing the information, the preload difference coefficient, stress coefficient and flange deformation coefficient are obtained respectively, and the tightening force evaluation coefficient is obtained after comprehensive analysis;

[0074] The process of obtaining the preload difference coefficient includes:

[0075] Obtain the design preload based on the medium pressure in the pipeline, flange sealing requirements, and the number of bolts;

[0076] When in the pre-tightened state, in order to ensure the gasket is sealed, the design pre-tightening force is

[0077] Among them, D G Is the diameter of the center circle where the gasket pressing force acts;

[0078] b is the effective sealing width of the gasket;

[0079] m is the gasket coefficient (related to the gasket material and structure, for example, the value of m for rubber asbestos gasket is between 2 and 3);

[0080] m is the medium pressure in the pipeline;

[0081] According to Hooke's law, within the elastic range, the elongation of a bolt is proportional to the tensile force it receives. The elongation of each bolt in operation is obtained using strain gauges. Assuming that each bolt is uniformly stressed, the axial forces of each bolt are accumulated to obtain the combined axial force.

[0082] Using the formula:

[0083] Where A (cross-sectional area of the bolt): calculated according to the nominal diameter of the bolt using the area formula of a circle;

[0084] E (elastic modulus of bolt material): Obtained by consulting the relevant material manual. Bolts made of different materials have different elastic moduli; for example, the elastic modulus of common carbon steel bolts is about 200-210GPa, and the elastic modulus of stainless steel bolts is 190-200GPa;

[0085] ΔL (bolt elongation): Use high-precision measuring instruments such as laser rangefinders, extensometers, or strain gauges for measurement. Ensure accuracy and precision during measurement to avoid inaccurate calculation results due to measurement errors.

[0086] L (original bolt length): The original length information is usually given in the bolt product specification. You can also use a measuring tool to directly measure the length of the bolt when it is not under stress.

[0087] After calculating the difference between the designed preload force and the comprehensive axial force, the absolute value is taken to obtain the preload deviation value;

[0088] Obtain the elongation of each bolt, preset an allowable range for the bolt elongation, compare the elongation of each bolt with the allowable range, and record the elongation of the bolt that is not within the allowable range as an abnormal elongation;

[0089] Arrange the abnormal elongations in descending order according to their values, and take the three largest abnormal elongations;

[0090] Mark the bolts corresponding to the three largest abnormal elongations and record them as marked bolts;

[0091] Connect the three marked bolts in a straight line to obtain a triangular shape. Calculate the area of the triangular shape and record it as the bolt position difference.

[0092] The preload force difference coefficient is obtained by comprehensively analyzing the preload deviation value and the bolt position difference value;

[0093] The weight factors of the preload deviation value and the bolt position difference value are calculated by multiplying the preload deviation value and the bolt position difference value with their corresponding weight factors, and then summing them to obtain the preload force difference coefficient;

[0094] The process of obtaining the stress coefficient includes:

[0095] The tensile stress of each bolt is obtained based on the axial force of each bolt and its minor diameter cross-sectional area;

[0096] By formula: Where A is the minor diameter cross-sectional area of the bolt;

[0097] Preset the standard tensile stress and compare the tensile stress of each bolt with the standard tensile stress. If the tensile stress of the bolt exceeds the standard tensile stress, the tensile stress is recorded as abnormal tensile stress, and the bolt corresponding to the abnormal tensile stress is recorded as an abnormal tensile bolt;

[0098] Obtain the number of bolts with abnormal tension, and divide the number of bolts with abnormal tension by the total number of bolts to obtain the stress abnormality ratio;

[0099] Obtain the positions of the bolts with different tensions, and draw a circle with any bolt with different tensions as the center and a preset radius. Obtain the number of bolts with different tensions within the circle and record it as the concentrated number.

[0100] Taking each of the different-tension bolts as the center of the circle, and following the above steps, obtain the concentrated number of each different-tension bolt within the circular range corresponding to the bolt;

[0101] Arrange the concentrated quantities in descending order according to their numerical values, extract the largest concentrated quantity, and divide the largest concentrated quantity by the number of abnormally pulled bolts to obtain the concentration ratio;

[0102] The preliminary coefficient is obtained by comprehensively analyzing the stress anomaly ratio and concentration ratio;

[0103] Mark the stress anomaly ratio and concentration ratio as YC and JI respectively and then insert them into the formula:

[0104]

[0105] Get the preliminary coefficients Where YC′ and JI′ are the stress anomaly reference ratio and the maximum allowable concentration ratio, respectively; a1 and a2 are the weight factors corresponding to the stress anomaly ratio and the concentration ratio, respectively;

[0106] Perform pipeline vibration analysis on both sides of the pipeline fixed by the flange bolt group to obtain the vibration deviation coefficient, including:

[0107] Vibration measuring points are set up on the pipelines on both sides, and the vibration frequencies of the measuring points are obtained at preset time intervals;

[0108] Arrange the vibration frequencies obtained at the same time point in descending order according to their numerical values, and determine the maximum vibration frequency and the corresponding vibration measurement point position;

[0109] A sphere is constructed with the vibration measurement point corresponding to the maximum vibration frequency as the center and a preset size as the radius to obtain all vibration frequencies within the spherical area; an allowable range of vibration frequencies is preset, and all vibration frequencies within the spherical area are sequentially compared with the preset allowable range of vibration frequencies, and vibration frequencies that are not within the preset allowable range of vibration frequencies are recorded as abnormal frequencies; the number of abnormal frequencies is recorded, and the number of abnormal frequencies is divided by the number of all vibration frequencies within the spherical area to obtain the abnormal rate;

[0110] Obtain the aberration rate corresponding to each time point in sequence, and arrange the obtained aberration rates in descending order according to their numerical values, extract the maximum aberration rate and the minimum aberration rate, calculate the difference between the maximum aberration rate and the minimum aberration rate, and obtain the vibration deviation coefficient;

[0111] The stress coefficient is obtained by combining the preliminary coefficient with the vibration deviation coefficient;

[0112] After normalizing the preliminary coefficient and the vibration deviation coefficient, the preliminary coefficient and the vibration deviation coefficient are used as the two right-angled sides of a right triangle, and the remaining side is connected to form a complete right triangle. The area of the right triangle is calculated and recorded as the stress coefficient.

[0113] The process of obtaining the flange deformation coefficient includes:

[0114] Obtaining image information of the flange, and after preprocessing the image, dividing the flange into regions to obtain flange sub-regions with the same area;

[0115] Perform feature extraction on each flange sub-region, extract features related to wear and corrosion, and mark the extracted features as damaged areas and corroded areas respectively;

[0116] Calculate the number of pixels in the damaged and corroded areas of each flange sub-region, and convert the number of pixels in the damaged and corroded areas of each flange sub-region into actual areas based on the image resolution to obtain the damaged and corroded areas of each flange sub-region;

[0117] Count the number of pixels: Count the number of pixels in the damaged and corroded areas of each flange sub-region. The number of pixels reflects the size of these areas in the image.

[0118] Area conversion: Since the number of pixels is only a measure in the image, in order to obtain the actual area, it is necessary to convert it according to the image resolution (the number of pixels per unit length). For example, if the image resolution is 10 pixels per millimeter, and the damaged area of a sub-region contains 100 pixels, then the actual area of the damaged area is 100 / (10*10) = 1 square millimeter. In this way, the damaged area and corrosion area of each flange sub-region are calculated;

[0119] Obtain the overlapping parts of the damaged area and the corroded area of each flange sub-area in turn, as well as the area of the overlapping parts, which are recorded as the overlapping area; accumulate the overlapping areas of each flange sub-area to obtain the total overlapping area;

[0120] Obtain the overlap and area: For each flange subregion, find the overlap between the damaged and corroded areas and calculate the area of this overlap. You can use image logic operations (such as intersection) to determine the overlap, then calculate the area of the overlap using the same method as above.

[0121] Cumulative total overlapping area: The overlapping areas of all flange sub-areas are summed to obtain the total overlapping area of the damaged and corroded areas in the entire flange image. This total overlapping area can be used as an important indicator to assess flange damage and the tightening strength of the pipeline flange bolt assembly.

[0122] Obtain the contours of the damaged area and the corroded area in each flange area, and arrange marking points along the contours of the damaged area and the corroded area in sequence;

[0123] Connect any two marked points on the outline of the damaged area with a straight line, record the straight line as the damaged line, sort the obtained damaged lines in descending order according to their numerical values, and extract the largest damaged line; obtain the largest damaged line in each flange sub-area in turn;

[0124] The maximum damage line in each flange area is accumulated to obtain the damage span value;

[0125] Following the above process of analyzing the damaged area to obtain the damage span value, the corrosion area in each flange sub-area is analyzed to obtain the corrosion span value;

[0126] The corrosion value is obtained by multiplying the damage span value and the corrosion span value;

[0127] Analyze the bolts in the flange image information to obtain the imbalance value between the flange and the bolts;

[0128] Mark each bolt from the flange image information and obtain the outline of each bolt;

[0129] Mark the center of each bolt's contour, obtain the center of the flange, connect the center of each bolt's end contour with the center of the flange with a straight line, and record the straight line as the bolt angle line;

[0130] Obtain the angle formed by adjacent bolt angle lines and record it as the line angle;

[0131] Obtain the linear angles formed by each adjacent bolt angle line in sequence, count the number of identical linear angles, and record the linear angle corresponding to the largest number of identical linear angles as the reference linear angle;

[0132] The difference between the remaining line structure angles and the reference line structure angle is calculated in turn to obtain the deviation angle;

[0133] The bolts corresponding to the overlapping bolt angle lines corresponding to adjacent deviation angles are recorded as deviated bolts. The end centers of each deviated bolt are obtained, and the end centers of each deviated bolt are connected with a straight line in a clockwise or counterclockwise direction. The length of the straight line is calculated and recorded as the unbalance value.

[0134] The flange deformation coefficient is obtained by comprehensively analyzing the total overlapping area, corrosion value, and imbalance value;

[0135] Preset weight factors for the total overlapping area, corrosion value, and imbalance value, and calculate and sum the products of the total overlapping area, corrosion value, and imbalance value with their corresponding weight factors to obtain the flange deformation coefficient;

[0136] The tightening force evaluation coefficient is obtained by comprehensively analyzing the preload difference coefficient, stress coefficient and flange deformation coefficient, including:

[0137] After normalizing the preload difference coefficient, stress coefficient, and flange deformation coefficient, the preload difference coefficient and stress coefficient are used as two sides of a triangle, and the angle of the side is preset to be within 40 degrees. The remaining side is connected to form a complete triangle. The flange deformation coefficient is used as the height of the triangle to construct a triangular pyramid model. The area of the triangular pyramid model is calculated and recorded as the tightening force evaluation coefficient.

[0138] Data evaluation: The tightening force level of the pipeline flange bolt group is evaluated based on the tightening force evaluation coefficient; specifically including:

[0139] Three groups of threshold value ranges are preset, each group of threshold value ranges corresponds to a tightening force level, and the tightening force evaluation coefficient is matched with the three groups of threshold value ranges to obtain the tightening force level corresponding to the tightening force evaluation coefficient, where the tightening force level includes unqualified, qualified, and excellent;

[0140] Result warning: carry out corresponding warning processing based on the tightening force level;

[0141] include:

[0142] If the tightening force level is unqualified, the bolt group will be marked and the marked bolt group information will be sent to the smart terminal of the relevant maintenance personnel. The maintenance personnel will use accurate tools to retighten according to the correct torque requirements.

[0143] When the tightening force rating is acceptable or excellent, record relevant information about the tightening operation, such as tightening time, operator, tools used, and torque values. These records facilitate tracing and analysis of any issues that arise during subsequent product or equipment operation, and conduct appropriate follow-up monitoring based on actual conditions. For example, regular spot checks can be conducted on tightening connections in key areas to verify that the tightening force remains within the acceptable range, ensuring product quality and stable equipment operation.

[0144] The above formulas are obtained by collecting a large amount of data and performing software simulation, and a formula close to the actual value is selected. The influencing weight factors and specific coefficient values in the formula are set by technical personnel in this field according to actual conditions, and can be adjusted and modified later.

[0145] The above description of the embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for evaluating the tightening force of a pipeline flange bolt group, characterized in that: include: Data collection: Obtain relevant information about flanges and bolt groups, including preload information, bolt stress information, and flange deformation information; Data processing: After analyzing the information, the preload difference coefficient, stress coefficient and flange deformation coefficient are obtained respectively, and the tightening force evaluation coefficient is obtained after comprehensive analysis; Data evaluation: Evaluate the tightening force level of the pipeline flange bolt group based on the tightening force evaluation coefficient; Result warning: Carry out corresponding warning processing based on the tightening force level.

2. A method for evaluating the tightening force of a pipeline flange bolt assembly according to claim 1, characterized in that: Data collection specifically includes: Bolt specifications, including nominal diameter, thread pitch, and material properties; Flange related parameters, including flange type, size, and material properties; The elongation of the bolt is measured by strain gauges; Information related to piping vibration; Gasket related information; Flange image information.

3. The method for evaluating the tightening force of a pipeline flange bolt assembly according to claim 2, characterized in that: The process of obtaining the preload difference coefficient includes: Obtain the design preload based on the medium pressure in the pipeline, flange sealing requirements, and the number of bolts; According to Hooke's law, within the elastic range, the elongation of a bolt is proportional to the tensile force it receives. The elongation of each bolt in operation is obtained using strain gauges. Assuming that each bolt is uniformly stressed, the axial forces of each bolt are accumulated to obtain the combined axial force. After calculating the difference between the designed preload force and the comprehensive axial force, the absolute value is taken to obtain the preload deviation value; Obtain the elongation of each bolt, preset an allowable range for the bolt elongation, compare the elongation of each bolt with the allowable range, and record the elongation of the bolt that is not within the allowable range as an abnormal elongation; Arrange the abnormal elongations in descending order according to their values, and take the three largest abnormal elongations; Mark the bolts corresponding to the three largest abnormal elongations and record them as marked bolts; Connect the three marked bolts in a straight line to obtain a triangular shape. Calculate the area of the triangular shape and record it as the bolt position difference. The preload force difference coefficient is obtained by comprehensive analysis of the preload deviation value and the bolt position difference value.

4. A method for evaluating the tightening force of a pipeline flange bolt assembly according to claim 3, characterized in that: The process of obtaining the stress coefficient includes: The tensile stress of each bolt is obtained based on the axial force of each bolt and its minor diameter cross-sectional area; Preset the standard tensile stress and compare the tensile stress of each bolt with the standard tensile stress. If the tensile stress of the bolt exceeds the standard tensile stress, the tensile stress is recorded as abnormal tensile stress, and the bolt corresponding to the abnormal tensile stress is recorded as an abnormal tensile bolt; Obtain the number of bolts with abnormal tension, and divide the number of bolts with abnormal tension by the total number of bolts to obtain the stress abnormality ratio; Obtain the positions of the bolts with different tensions, and draw a circle with any bolt with different tensions as the center and a preset radius. Obtain the number of bolts with different tensions within the circle and record it as the concentrated number. Taking each of the different-tension bolts as the center of the circle, and following the above steps, obtain the concentrated number of each different-tension bolt within the circular range corresponding to the bolt; Arrange the concentrated quantities in descending order according to their numerical values, extract the largest concentrated quantity, and divide the largest concentrated quantity by the number of abnormally pulled bolts to obtain the concentration ratio; The preliminary coefficient is obtained by comprehensively analyzing the stress anomaly ratio and concentration ratio; Perform pipeline vibration analysis on both sides of the pipelines fixed by the flange bolt group to obtain the vibration deviation coefficient; The stress coefficient is obtained by comprehensively processing the preliminary coefficient and the vibration deviation coefficient.

5. The method for evaluating the tightening force of a pipeline flange bolt assembly according to claim 4, characterized in that: The process of obtaining the flange deformation coefficient includes: Obtaining image information of the flange, and after preprocessing the image, dividing the flange into regions to obtain flange sub-regions with the same area; Perform feature extraction on each flange sub-region, extract features related to wear and corrosion, and mark the extracted features as damaged areas and corroded areas respectively; Calculate the number of pixels in the damaged and corroded areas of each flange sub-region, and convert the number of pixels in the damaged and corroded areas of each flange sub-region into actual areas based on the image resolution to obtain the damaged and corroded areas of each flange sub-region; Obtain the overlapping parts of the damaged area and the corroded area of each flange sub-area in turn, as well as the area of the overlapping parts, which are recorded as the overlapping area; accumulate the overlapping areas of each flange sub-area to obtain the total overlapping area; Obtain the contours of the damaged area and the corroded area in each flange area, and arrange marking points along the contours of the damaged area and the corroded area in sequence; Connect any two marked points on the outline of the damaged area with a straight line, record the straight line as the damaged line, sort the obtained damaged lines in descending order according to their numerical values, and extract the largest damaged line; obtain the largest damaged line in each flange sub-area in turn; The maximum damage line in each flange area is accumulated to obtain the damage span value; Following the above process of analyzing the damaged area to obtain the damage span value, the corrosion area in each flange sub-area is analyzed to obtain the corrosion span value; The corrosion value is obtained by multiplying the damage span value and the corrosion span value; Analyze the bolts in the flange image information to obtain the imbalance value between the flange and the bolts; The flange deformation coefficient is obtained by comprehensive analysis of the total overlapping area, corrosion value and imbalance value.

6. A method for evaluating the tightening force of a pipeline flange bolt assembly according to claim 5, characterized in that: The tightening force evaluation coefficient is obtained by comprehensively analyzing the preload difference coefficient, stress coefficient and flange deformation coefficient, including: After normalizing the preload difference coefficient, stress coefficient, and flange deformation coefficient, the preload difference coefficient and stress coefficient are used as two sides of a triangle, respectively. The angles of the two sides are preset to be within 40 degrees. The remaining side is connected to form a complete triangle. The flange deformation coefficient is used as the height of the triangle to construct a triangular pyramid model. The area of the triangular pyramid model is calculated and recorded as the tightening force evaluation coefficient.

7. A method for evaluating the tightening force of a pipeline flange bolt assembly according to claim 6, characterized in that: The tightening force level of the pipeline flange bolt group is evaluated, including: Three groups of threshold value ranges are preset, each group of threshold value ranges corresponds to a tightening force level, and the tightening force evaluation coefficient is matched with the three groups of threshold value ranges to obtain the tightening force level corresponding to the tightening force evaluation coefficient, where the tightening force level includes unqualified, qualified, and excellent.

8. The method for evaluating the tightening force of a pipeline flange bolt assembly according to claim 7, characterized in that: Based on the tightening force level, corresponding early warning processing is carried out, including: When the tightening force level is unqualified: the bolt group is marked and the marked bolt group information is sent to the smart terminal of the relevant maintenance personnel. The maintenance personnel use accurate tools to retighten according to the correct torque requirements.

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