Method and apparatus for evaluating the degree of creep damage to steam piping

Abstract

This invention provides a creep damage evaluation method that can accurately evaluate the degree of creep damage at the connection between a main pipe and at least one pipe support in a steam piping system. [Solution] In a method for evaluating the degree of creep damage to steam piping, measured values ​​of parameters relating to the degree of dimensional change of at least one of the main pipe and the first pipe support due to use over a certain period are obtained, creep characteristic information indicating the creep characteristics of the connection between the main pipe and the first pipe support is obtained, stress analysis of the connection between the main pipe and the first pipe support is performed using the creep characteristic information, calculated values ​​of the parameters are calculated based on the results of the stress analysis of the connection between the main pipe and the first pipe support, creep characteristic information to be used to evaluate the degree of creep damage to the connection between the main pipe and at least one pipe support is determined based on a comparison of the measured and calculated values ​​of the parameters, and the degree of creep damage to the connection between the main pipe and at least one pipe support is evaluated based on the determined creep characteristic information.

Description

[Technical Field]

[0001] The present disclosure relates to a method for evaluating creep damage degree of steam piping and an apparatus for evaluating creep damage degree of steam piping. [Background Art]

[0002] Patent Document 1 discloses a life evaluation system comprising: a first stress calculation unit that takes a base material portion around a nozzle hole of boiler piping as a first evaluation site that is a target of life evaluation, and calculates life evaluation stress used for evaluating the life of the first evaluation site based on the nozzle type, main pipe dimensions, nozzle dimensions, evaluation pressure, evaluation temperature, and steel type related to the first evaluation site; and a first life evaluation unit that evaluates the life of the first evaluation site based on the life evaluation stress. [Prior Art Document] [Patent Document]

[0003] [Patent Document 1] International Publication No. 2023-032720 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] Even if the life of an evaluation site is evaluated based on the material of the evaluation site as described in Patent Document 1, the actual creep damage degree varies depending on the heat of the material of the evaluation site (a material actually produced with different chemical components or heat treatment conditions within the scope of material standards), and thus the creep damage degree may not be evaluated with high accuracy.

[0005] In view of the foregoing circumstances, an object of at least one embodiment of the present disclosure is to provide a method for evaluating creep damage degree of steam piping and an apparatus for evaluating creep damage degree of steam piping, which can accurately evaluate the creep damage degree of a connection portion between a main pipe and at least one nozzle in steam piping. [Means for Solving the Problem]

[0006] To achieve the above objective, a method for evaluating the degree of creep damage to a steam pipe according to at least one embodiment of the present disclosure is a method for evaluating the degree of creep damage to a steam pipe, which evaluates the degree of creep damage to a connection between a main pipe and at least one pipe support in a steam pipe, The at least one pipe stand includes a first pipe stand connected to the main pipe, The steam piping creep damage evaluation method is as follows: A measurement value acquisition step to acquire measurement values ​​of parameters relating to the degree of dimensional change of at least one of the main pipe and the first pipe support due to the use of the steam piping for a certain period of time, A creep characteristic information acquisition step involves acquiring creep characteristic information that shows the creep characteristics of the connection between the main pipe and the first pipe support, A stress analysis step in which stress analysis is performed on the connection between the main pipe and the first pipe support using the creep characteristic information, A calculation value calculation step in which the calculated values ​​of the parameters are calculated based on the results of the stress analysis of the connection part between the main pipe and the first pipe support, A creep characteristic information determination step, which determines creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the at least one pipe support, based on a comparison of the measured value and the calculated value of the parameter, A creep damage evaluation step, which evaluates the degree of creep damage at the connection between the main pipe and the at least one pipe support based on the creep characteristic information determined in the creep characteristic information determination step, It is equipped with. [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, a method and apparatus for evaluating the degree of creep damage in steam piping are provided, which can accurately evaluate the degree of creep damage at the connection between a main pipe and at least one pipe support in steam piping. [Brief explanation of the drawing]

[0008] [Figure 1]This is a schematic cross-sectional view of a steam pipe 4, which is the target of creep damage evaluation by a creep damage evaluation device 100 according to one embodiment of the present disclosure. [Figure 2] This is a block diagram showing an example of the hardware configuration of a creep damage evaluation device 100 according to one embodiment of the present disclosure. [Figure 3] Figure 2 is a block diagram showing an example of the functional configuration of the creep damage evaluation device 100. [Figure 4] This flowchart shows an example of a creep damage assessment method for evaluating the degree of creep damage to steam piping 4. [Figure 5] This is a schematic cross-sectional view illustrating the flattening ratio Bf of the pipe base hole 12. [Figure 6] This is a diagram illustrating how to create the creep rupture curve L2. [Figure 7] This is a diagram illustrating how to create the creep rupture curve L4. [Figure 8] This is a diagram illustrating how to create the creep rupture curve L6. [Figure 9] This flowchart shows another example of a creep damage assessment method for evaluating the degree of creep damage to steam piping 4. [Figure 10] This flowchart shows yet another example of a creep damage assessment method for evaluating the degree of creep damage to steam piping 4. [Figure 11] This is a schematic cross-sectional view showing another example of the configuration of the steam piping 4. [Modes for carrying out the invention]

[0009] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of the invention, but are merely illustrative examples. For example, expressions representing relative or absolute arrangements such as "in a certain direction", "along a certain direction", "parallel", "perpendicular", "center", "concentric" or "coaxial" shall not only strictly represent such arrangement, but also represent a state of relative displacement with tolerance, or an angle and distance that allow obtaining the same function. For example, expressions indicating that things are in an equal state such as "identical", "equal" and "homogeneous" shall not only strictly represent an equal state, but also represent a state where there is a difference within a range that allows obtaining the same function, or a difference within tolerance. For example, expressions representing shapes such as quadrangular shape or cylindrical shape shall not only represent shapes such as quadrangular shape or cylindrical shape in a geometrically strict sense, but also represent shapes including irregularities, chamfered parts and the like within a range that allows obtaining the same effect. On the other hand, expressions such as "comprise", "include", "have", "contain" or "possess" referring to one component are not exclusive expressions that exclude the presence of other components.

[0010] Figure 1 is a schematic cross-sectional view of a steam pipe 4 that is an evaluation target of creep damage degree by a creep damage degree evaluation apparatus according to an embodiment of the present disclosure. The steam pipe 4 shown in Figure 1 is a steam pipe provided in a boiler 2, and high-temperature and high-pressure steam generated by the boiler 2 flows inside the steam pipe 4. The steam pipe 4 includes a main pipe 6 and a nozzle 8 (first nozzle) connected to the main pipe 6. One end of the nozzle 8 is connected to the outer peripheral surface of the main pipe 6 via a welded portion 9. The nozzle 8 is formed in a substantially cylindrical shape, and the outer diameter of the nozzle 8 is smaller than the outer diameter of the main pipe 6. A through hole 10 is formed on the outer peripheral surface of the main pipe 6, and the internal space of the main pipe 6 and a nozzle bore 12 that is the internal space of the nozzle 8 communicate with each other via the through hole 10. Hereinafter, an example of an evaluation method for evaluating the creep damage degree of a connecting portion 14 between the main pipe 6 and the nozzle 8 will be described. The connecting portion 14 between the main pipe 6 and the nozzle 8 includes a portion of the main pipe 6 connected to the nozzle 8, a portion of the nozzle 8 connected to the main pipe 6, and the welded portion 9.

[0011] FIG. 2 is a block diagram showing an example of the hardware configuration of a creep damage degree evaluation apparatus 100 according to an embodiment of the present disclosure. FIG. 3 is a block diagram showing an example of the functional configuration of the creep damage degree evaluation apparatus 100 shown in FIG. 2. FIG. 4 is a flowchart showing an example of a creep damage degree evaluation method for evaluating the creep damage degree of a steam pipe 4 (see FIG. 1) using the creep damage degree evaluation apparatus 100 shown in FIGS. 2 and 3.

[0012] As shown in FIG. 2, the creep damage degree evaluation apparatus 100 includes, for example, a processor 91, a RAM (Random Access Memory) 92, a ROM (Read Only Memory) 93, an HDD (Hard Disk Drive) 94, an input I / F 96, and an output I / F 98, and is configured using a computer in which these components are connected to each other via a bus 95. Further, the creep damage degree evaluation apparatus 100 is configured when the computer executes a program that implements each function of the creep damage degree evaluation apparatus 100. The functions of each unit in the creep damage degree evaluation apparatus 100 described below are implemented, for example, by loading a program stored in the ROM 93 into the RAM 92, executing the program by the processor 91, and reading and writing data in the RAM 92 and the ROM 93. The hardware constituting the creep damage degree evaluation apparatus 100 may be concentrated in one location, or may be distributed and provided in a plurality of locations.

[0013] As shown in FIG. 3, the creep damage degree evaluation apparatus 100 includes a measurement value acquisition unit 20, a storage unit 22, a stress analysis unit 24, a calculated value calculation unit 26, a creep characteristic information determination unit 28, and a creep damage degree evaluation unit 30. An example of the function of each unit of the creep damage degree evaluation apparatus 100 will be described below with reference to FIG. 4.

[0014] As shown in Figure 4, in S101, the boiler 2 is operated for a certain period of time, the steam piping 4 is used for that period of time, and the first parameter described below is measured. In this specification, the first parameter is a parameter relating to the degree of dimensional change of at least one of the main pipe 6 and the pipe support 8 due to the operation of the boiler 2 for a certain period of time. The first parameter may be, for example, the expansion rate of the main pipe 6, the expansion rate of the pipe support 8, the ratio of the expansion rate of the main pipe 6 to the expansion rate of the pipe support 8, or the flattening ratio of the pipe support hole 12. The expansion rate of the main pipe 6 is the value As shown in the following formula (a), the expansion rate of the pipe support 8 is the value Bs shown in the following formula (b), and the flattening ratio of the pipe support hole 12 is the value Bf shown in the following formula (c). As = (Da1 - Da0) / Da0 ... (a) Bs = (Db1 - Db0) / Db0 ... (b) Bf = (d1 - d2) / d1 ... (c)

[0015] Here, in equation (a) above, Da1 is the outer diameter of the main tube 6 measured after a certain period of operation of the boiler 2 (i.e., the outer diameter of the main tube 6 after deformation due to a certain period of operation of the boiler 2), and Da0 is the outer diameter of the main tube 6 before a certain period of operation of the boiler 2 (i.e., the outer diameter of the main tube 6 before deformation due to a certain period of operation of the boiler 2). Note that Da0 may be the outer diameter of the main tube 6 measured before a certain period of operation of the boiler 2, or it may be the outer diameter of the main tube 6 when it was new, obtained from a source such as a mill sheet for the main tube 6.

[0016] Furthermore, in formula (b) above, Db1 is the outer diameter of the tube grommets 8 measured after a certain period of operation of the boiler 2 (i.e., the outer diameter of the tube grommets 8 after deformation due to a certain period of operation of the boiler 2), and Db0 is the outer diameter of the tube grommets 8 before a certain period of operation of the boiler 2 (i.e., the outer diameter of the tube grommets 8 before deformation due to a certain period of operation of the boiler 2). Note that Db0 may be the outer diameter of the tube grommets 8 measured before a certain period of operation of the boiler 2, or it may be the outer diameter of the tube grommets 8 when new, obtained from a source such as a mill sheet for the tube grommets 8.

[0017] Furthermore, in equation (c) above, d1 is the major axis of the tubing hole 12 measured after a certain period of operation of the boiler 2, and d2 is the minor axis of the tubing hole 12 measured after a certain period of operation of the boiler 2 (see Figure 5). Note that the major axis of the tubing hole 12 means the maximum value of the dimensions of the tubing hole 12 in the direction perpendicular to the axial direction of the tubing hole 12 in the cross section of the tubing hole 12 perpendicular to the axial direction of the tubing 8, and the minor axis of the tubing hole 12 means the minimum value of the dimensions of the tubing hole 12 in the direction perpendicular to the axial direction of the tubing hole 12 in the cross section of the tubing hole 12 perpendicular to the axial direction of the tubing 8. However, the terms "major axis" and "minor axis" in this specification do not presuppose that the cross-sectional shape of the tubing hole 12 is elliptical.

[0018] Furthermore, when measuring the expansion ratio As of the main pipe 6 using equation (a), the axial distance Ea of the main pipe 6 between the measurement position Pa (see Figure 1) of the outer diameter of the main pipe 6 and the pipe support 8 may satisfy the following equation (d). Ea≧2.5 / √(RT) ···(d) Here, R is the average radius of the main pipe 6, T is the wall thickness of the main pipe 6, and √(RT) is the square root of the product of R and T. Note that the average radius of the main pipe 6 is the value obtained by dividing the sum of the outer diameter and inner diameter of the main pipe 6 by 4.

[0019] Furthermore, when measuring the expansion ratio Bs of the pipe support 8 using equation (b), the axial distance Eb of the pipe support 8 between the measurement position Pb of the outer diameter of the pipe support 8 (see Figure 1) and the main pipe 6 may satisfy the following equation (e). Eb≧2.5 / √(rt) ···(e) Here, r is the average radius of pipe support 8, t is the wall thickness of pipe support 8, and √(rt) is the square root of the product of r and t. Note that the average radius of pipe support 8 is the value obtained by dividing the sum of the outer and inner diameters of pipe support 8 by 4.

[0020] Furthermore, when measuring the flattening ratio Bf of the pipe support hole 12 using equation (c), the axial distance Ec of the pipe support 8 between the measurement position Pc (see Figure 1) of the major axis d1 and minor axis d2 of the pipe support hole 12 and the main pipe 6 may satisfy the following equation (f). Ec≧2.5 / √(rt) ···(f) Here, r is the average radius of pipe support 8, t is the wall thickness of pipe support 8, and √(rt) is the square root of the product of r and t.

[0021] In S102, the measurement value acquisition unit 20 acquires the measurement value of the first parameter measured in S101. In S103, the stress analysis unit 24 obtains creep characteristic information from the memory unit 22, which shows the creep characteristics of the connection portion 14 between the main pipe 6 and the pipe support 8. Here, the creep characteristic information of the connection portion 14 may include, for example, creep characteristic information showing the creep characteristics of the main pipe 6, pipe support 8, and welded portion 9 in the connection portion 14. Also in S103, the stress analysis unit 24 obtains from the memory unit 22 the operating time of the boiler 2, which corresponds to the length of a certain period during which the boiler 2 was operated in S101, the operating conditions of the boiler 2, the three-dimensional shape data of the connection portion 14 (for example, the three-dimensional shape data of the main pipe 6, pipe support 8, and welded portion 9 in the connection portion 14), and the material of the connection portion 14 (for example, the material of the main pipe 6, pipe support 8, and welded portion 9 in the connection portion 14). The operating conditions for boiler 2 here are the operating conditions necessary to perform stress analysis on the connection point 14 between the main pipe 6 and the pipe support 8 in the steam piping 4 (for example, the internal pressure and temperature of the steam piping 4 at the connection point 14).

[0022] The creep characteristic information acquired by the stress analysis unit 24 in S103 includes a creep rupture curve (for example, the creep rupture curves for the main pipe 6, the pipe support 8, and the welded joint 9 at the connection 14 between the main pipe 6 and the pipe support 8) showing the relationship between stress and creep rupture time, and / or creep rate information showing the relationship between creep rupture time and creep rate.

[0023] In S104, the stress analysis unit 24 performs a stress analysis of the connection part 14 using the FEM (finite element method) based on the creep characteristic information acquired in S103 (for example, the creep characteristic information of the main pipe 6, pipe support 8, and welded part 9 in the connection part 14), the operating time of the boiler 2, the operating conditions of the boiler 2, and the three-dimensional shape data and material of the connection part 14. In S104, the stress analysis unit 24 calculates the strain distribution of the connection part 14 at a point in time when the operating time of the boiler 2 has elapsed, which corresponds to the length of the aforementioned period during which the boiler 2 was operated, as a result of the above stress analysis.

[0024] Furthermore, in S105, the calculation unit 26 calculates the calculated value of the first parameter (the first parameter obtained in S102) based on the strain distribution of the connection part 14, which is the result of the stress analysis. For example, if the measured value of the bulging ratio of the main pipe 6 was obtained as the measured value of the first parameter in S102, then in S105, the calculated value of the bulging ratio of the main pipe 6 is calculated as the calculated value of the first parameter based on the strain distribution of the connection part 14.

[0025] In S106, the creep characteristic information determination unit 28 corrects the creep characteristic information (creep characteristic information used for stress analysis by the stress analysis unit 24) acquired in S103 based on a comparison between the measured value of the first parameter acquired by the measurement value acquisition unit 20 and the calculated value of the first parameter calculated by the calculation value calculation unit 26. For example, if the measured value of the first parameter acquired by the measurement value acquisition unit 20 is greater than the calculated value of the first parameter calculated by the calculation value calculation unit 26, it can be inferred that the actual creep rate in the steam pipe 4 where the first parameter was measured is greater than the creep rate obtained from the creep characteristic information. Therefore, the creep characteristic information determination unit 28 corrects the creep rupture curve in the creep characteristic information so that the creep rupture time under the same stress conditions is shortened (the creep rate is increased). Furthermore, if the measured value of the first parameter acquired by the measurement value acquisition unit 20 is smaller than the calculated value of the first parameter calculated by the calculation value calculation unit 26, it can be inferred that the actual creep rate in the steam pipe 4 where the first parameter was measured is smaller than the creep rate obtained from the creep characteristic information. Therefore, the creep characteristic information determination unit 28 corrects the creep rupture curve in the creep characteristic information so that the creep rupture time under the same stress conditions becomes longer (the creep rate becomes smaller). The creep characteristic information determination unit 28 then determines the corrected creep characteristic information to be used for evaluating the degree of creep damage at the connection part 14 between the main pipe 6 and the pipe support 8.

[0026] In S107, the creep damage evaluation unit 30 evaluates (calculates) the creep damage of the connection portion 14 between the main pipe 6 and the pipe support 8 based on the creep characteristic information (corrected creep characteristic information) determined by the creep characteristic information determination unit 28. In S107, the creep damage of a location different from the location where the measurement value of the first parameter at the connection portion 14 between the main pipe 6 and the pipe support 8 was measured may be evaluated based on the creep characteristic information determined by the creep characteristic information determination unit 28. For example, if the measurement location of the first parameter in S102 is one of the locations Pa, Pb, or Pc in Figure 1 (for example, when measuring the bulging rate of the main pipe 6 at location Pa, when measuring the expansion rate of the pipe support 8 at location Pb, or when measuring the flattening ratio of the pipe support hole 12 at location Pc), in S107, the creep damage of the area 19 (see Figure 1) around the through hole 10 in the main pipe 6 may be evaluated.

[0027] In this way, the creep damage evaluation device 100 compares a calculated value obtained from the results of a stress analysis using creep characteristic information that shows the creep characteristics of the connection part 14 between the main pipe 6 and the pipe support 8 with a measured value measured in the steam piping 4 that was actually used for a certain period of time, for the first parameter relating to the degree of dimensional change of at least one of the main pipe 6 and the pipe support 8, and determines the creep characteristic information to be used to evaluate the creep damage of the connection part 14 based on this comparison. Here, the measured value of the first parameter measured in the steam piping 4 that was actually used for a certain period of time is a value that reflects the heat creep characteristics of the material of the connection part 14 between the main pipe 6 and the pipe support 8, and is a value that reflects the actual strength of the connection part 14 between the main pipe 6 and the pipe support 8 (especially the actual strength of the main pipe 6). Therefore, by determining the creep characteristic information used to evaluate the degree of creep damage at the connection point 14 between the main pipe 6 and the pipe support 8 based on a comparison of the measured and calculated values ​​of the first parameter, the creep characteristic information used to evaluate the degree of creep damage at the connection point 14 between the main pipe 6 and the pipe support 8 can be determined considering the actual strength of the connection point 14 between the main pipe 6 and the pipe support 8. Thus, the degree of creep damage at the connection point 14 between the main pipe 6 and the pipe support 8 can be evaluated with high accuracy.

[0028] Furthermore, the bulging rate of the main pipe 6 is a parameter that changes according to the actual strength of the main pipe 6, and since the pipe support 8 is constrained to the main pipe 6, the bulging rate of the pipe support 8 and the flattening ratio of the pipe support hole 12 are also parameters that change according to the actual strength of the main pipe 6. For this reason, as described above, by adopting the bulging rate of the main pipe 6, the bulging rate of the pipe support 8, the ratio of the bulging rate of the main pipe 6 to the bulging rate of the pipe support 8, or the flattening ratio of the pipe support hole 12 of the pipe support 8 as the first parameter, the actual strength of the connection part 14 between the main pipe 6 and the pipe support 8 (especially the actual strength of the main pipe 6) can be accurately reflected in the creep characteristic information used to evaluate the degree of creep damage of the connection part 14 between the main pipe 6 and the pipe support 8. Therefore, the degree of creep damage of the connection part 14 between the main pipe 6 and the pipe support 8 can be evaluated with high accuracy.

[0029] Next, we will describe some examples of creep characteristic information obtained in S103. In some embodiments, a machine learning model may be created in advance to learn the relationship between mill sheet information (information showing the chemical composition of the material and the heat treatment history, etc.) and the creep rupture curve for the material of the main pipe 6, and creep characteristic information may be acquired using this machine learning model. In this case, the creep characteristic information acquired by the stress analysis unit 24 in S103 includes the creep rupture curve L1 of the main pipe 6, which is output from the machine learning model by inputting the mill sheet information of the main pipe 6 into the machine learning model. This makes it possible to acquire a creep rupture curve L1 with high prediction accuracy corresponding to the heat of the material of the main pipe 6 in the creep characteristic acquisition step. This makes it possible to accurately evaluate the degree of creep damage to the main pipe 6 at the connection part 14 between the main pipe 6 and the pipe support 8. Furthermore, compared to the case in which creep rupture curves L2, L4, and L6 described below are created, there is an advantage in that it is not necessary to perform creep rupture tests on the main pipe 6 of the actual boiler 2.

[0030] In some embodiments, as shown in Figures 6 to 8, for example, a creep rupture test may be performed on a sample (long-term used material from the actual boiler 2) taken from the main pipe 6 of the actual boiler 2 to measure the creep rupture time corresponding to a specific stress for the main pipe 6. Based on the results of the creep rupture test (creep rupture time corresponding to a specific stress), the average rupture curve L0 corresponding to the material of the main pipe 6 may be corrected. In this case, the creep characteristic information acquired by the stress analysis unit 24 in S102 includes the creep rupture curve obtained by correcting the average rupture curve L0. The average rupture curve L0 is a known average creep rupture curve for the material of the main pipe 6 (a creep rupture curve in which the heat difference of the material cannot be reflected in the prediction result of the degree of creep damage), and may be, for example, a creep rupture curve established by a public institution. In this way, by correcting the average fracture curve L0 for the material of the main pipe 6 based on the results of the creep fracture test, it is possible to create a creep fracture curve that reflects the actual strength of the main pipe 6 after long-term use, and thus the degree of creep damage to the main pipe 6 at the connection point 14 between the main pipe 6 and the pipe support 8 can be evaluated with accuracy.

[0031] When predicting creep damage using a typical average fracture curve L0, the difference in heat distribution between materials cannot be reflected in the prediction results, and the accuracy of the creep damage prediction tends to be low, especially under low-stress (long-life) stress conditions. For this reason, in some examples shown in Figures 6 to 8, the average fracture curve L0 corresponding to the material of the main pipe 6 is corrected based on the results of creep fracture tests performed under low-stress (long-life) stress conditions. This makes it possible to create a creep fracture curve with high prediction accuracy over a wide range of stress conditions, from low to high stress.

[0032] In one embodiment, for example, as shown in Figure 6, a creep rupture curve L2 may be created by translating the average rupture curve L0 in the x-axis direction (the direction of the axis indicating rupture time) so that it passes through a point indicating the result of a creep rupture test (a point indicating the measurement result of the creep rupture time corresponding to a specific stress). In this case, the creep characteristic information acquired by the stress analysis unit 24 includes the above creep rupture curve L2. When creating the creep rupture curve L2 as described above, there is an advantage in that fewer creep rupture tests are required compared to the creep rupture curve L6 described later.

[0033] In one embodiment, for example, as shown in Figure 7, a creep rupture curve L4 may be created by determining the intersection Q1 between a straight line L3 having a predetermined slope that passes through a point indicating the result of a creep rupture test (a point indicating the measurement result of the creep rupture time corresponding to a specific stress) and the average rupture curve L0, and replacing only the portion of the average rupture curve L0 on the longer life side (the side with a longer rupture time) than the intersection Q1 with the straight line L3. In this case, the creep characteristic information acquired by the stress analysis unit 24 includes the above creep rupture curve L4. Since the slope of the long life side portion of the creep rupture curve is generally constant, creating the creep rupture curve L4 as described above has the advantage of superior prediction accuracy of creep damage on the long life side, and has the advantage of requiring fewer creep rupture tests compared to the creep rupture curve L6 described later.

[0034] In one embodiment, as shown in Figure 8, creep rupture tests are performed on multiple samples (two samples in the illustrated example) taken from two different locations with different stress levels in the main tube 6 of the actual boiler 2. By doing so, multiple creep rupture times corresponding to the multiple stress levels are measured for the main tube 6, and the average rupture curve L0 corresponding to the material of the main tube 6 may be corrected based on multiple points showing the results of the creep rupture tests (multiple points showing the measurement results of creep rupture times corresponding to the multiple stress levels). In this case, for example, the intersection point Q2 of the straight line L5 passing through the two points showing the results of the creep rupture tests and the average rupture curve L0 may be found, and the creep rupture curve L6 may be created by replacing only the portion of the average rupture curve L0 on the longer life side than the intersection point Q2 with the straight line L5. In this case, the creep characteristic information acquired by the stress analysis unit 24 includes the creep rupture curve L6. When the creep rupture curve L6 is created in the manner described above, there is an advantage in that the prediction accuracy of the creep damage degree on the long life side is excellent.

[0035] Figure 9 is a flowchart showing another example of a creep damage evaluation method for evaluating the creep damage of steam piping 4 (see Figure 1) using the creep damage evaluation device 100 shown in Figures 2 and 3.

[0036] The contents of S201, S202, S203, S204, and S205 in the flow shown in Figure 9 are basically the same as the contents of S101, S102, S103, S104, and S105 in the flow shown in Figure 4, respectively. Therefore, redundant explanations will be omitted, and the differences from the flow shown in Figure 4 will be explained here.

[0037] In S206, the creep characteristic information determination unit 28 compares the measured value of the first parameter acquired by the measurement value acquisition unit 20 with the calculated value of the first parameter calculated by the calculation value calculation unit 26, and determines whether the absolute value of the difference between the measured value and the calculated value of the first parameter is less than or equal to a threshold.

[0038] If the creep characteristic information determination unit 28 determines in S206 that the absolute value of the difference between the measured value and the calculated value of the first parameter is not below a threshold, then in S207, the creep characteristic information determination unit 28 corrects the creep characteristic information used in the stress analysis in S204. In this case, for example, if the measured value of the first parameter acquired by the measurement value acquisition unit 20 is greater than the calculated value of the first parameter calculated by the calculation value calculation unit 26, it can be inferred that the actual creep rate in the steam pipe 4 where the first parameter was measured is greater than the creep rate obtained from the creep characteristic information. Therefore, the creep characteristic information determination unit 28 corrects the creep rupture curve in the creep characteristic information so that the creep rupture time under the same stress conditions becomes shorter (the creep rate becomes larger). Furthermore, if the measured value of the first parameter acquired by the measurement value acquisition unit 20 is smaller than the calculated value of the first parameter calculated by the calculation value calculation unit 26, it can be inferred that the actual creep rate in the steam pipe 4 where the first parameter was measured is smaller than the creep rate obtained from the creep characteristic information. Therefore, the creep characteristic information determination unit 28 corrects the creep rupture curve in the creep characteristic information so that the creep rupture time under the same stress conditions becomes longer (the creep rate becomes smaller). If the creep characteristic information is corrected in S207, the process returns to S203, where the stress analysis unit 24 acquires the corrected creep characteristic information corrected in S207 from the creep characteristic information determination unit 28. Then, S204, S205, and S206 are performed again using the corrected creep characteristic information.

[0039] If the creep characteristic information determination unit 28 determines in S206 that the absolute value of the difference between the measured value and the calculated value of the first parameter is less than or equal to a threshold, the creep characteristic information determination unit 28 determines the creep characteristic information used to calculate the calculated value of the first parameter that satisfies the conditions of S206 to be the creep characteristic information used to evaluate the degree of creep damage of the connection part 14 between the main pipe 6 and the pipe support 8, and proceeds to S208.

[0040] In S208, the creep damage evaluation unit 30 evaluates the creep damage of the connection portion 14 between the main pipe 6 and the pipe support 8 based on the creep characteristic information determined by the creep characteristic information determination unit 28. In S208, the creep damage of a location different from the location where the measured value of the first parameter at the connection portion 14 between the main pipe 6 and the pipe support 8 was measured may be evaluated based on the creep characteristic information determined by the creep characteristic information determination unit 28. For example, if the measurement location of the first parameter in S202 is any of the locations Pa, Pb, or Pc in Figure 1 (for example, when measuring the bulging rate of the main pipe 6 at location Pa, when measuring the expansion rate of the pipe support 8 at location Pb, or when measuring the flattening ratio of the pipe support hole 12 at location Pc), S208 may evaluate the creep damage of the area 19 (see Figure 1) around the through hole 10 in the main pipe 6.

[0041] Thus, in the creep damage evaluation method shown in Figure 9, the first parameter relating to the degree of dimensional change of at least one of the main pipe 6 and the pipe support 8 is compared with a calculated value obtained from the results of a stress analysis using creep characteristic information that shows the creep characteristics of the connection part 14 between the main pipe 6 and the pipe support 8, and with a measured value actually measured in the steam piping 4 used for a certain period of time. Based on this comparison, the creep characteristic information used to evaluate the creep damage of the connection part 14 is determined. Therefore, similar to the creep damage evaluation method shown in Figure 4, the creep characteristic information used to evaluate the creep damage of the connection part 14 between the main pipe 6 and the pipe support 8 can be determined considering the actual strength of the connection part 14 between the main pipe 6 and the pipe support 8, and the creep damage of the connection part 14 between the main pipe 6 and the pipe support 8 can be evaluated with high accuracy.

[0042] Figure 10 is a flowchart showing yet another example of a creep damage evaluation method for evaluating the creep damage of steam piping 4 (see Figure 1) using the creep damage evaluation device 100 shown in Figures 2 and 3.

[0043] The contents of S301 and S302 in the flow shown in Figure 10 are the same as the contents of S101 and S102 in the flow shown in Figure 4, respectively. Therefore, redundant explanations will be omitted, and the differences from the flow shown in Figure 4 will be explained here.

[0044] As shown in Figure 10, in S303, the stress analysis unit 24 obtains from the memory unit 22 multiple creep characteristic information indicating the creep characteristics of the connection portion 14 between the main pipe 6 and the pipe support 8. Also in S303, the stress analysis unit 24 obtains from the memory unit 22 the operating time of the boiler 2, which corresponds to the length of a certain period during which the boiler 2 was operated in S301, the operating conditions of the boiler 2, the three-dimensional shape data of the connection portion 14 (for example, the three-dimensional shape data of the main pipe 6, pipe support 8, and welded portion 9 in the connection portion 14), and the material of the connection portion 14 (for example, the material of the main pipe 6, pipe support 8, and welded portion 9 in the connection portion 14). The operating conditions of the boiler 2 here are the operating conditions necessary to perform stress analysis of the connection portion 14 between the main pipe 6 and the pipe support 8 in the steam piping 4 (for example, the internal pressure and temperature of the steam piping 4 in the connection portion 14).

[0045] Each of the multiple creep characteristic information acquired by the stress analysis unit 24 in S303 includes a creep rupture curve showing the relationship between stress and creep rupture time at the connection part 14 between the main pipe 6 and the pipe support 8 (for example, the creep rupture curves for the main pipe 6, pipe support 8, and welded part 9 at the connection part 14) and / or creep velocity information showing the relationship between creep rupture time and creep velocity. Furthermore, each of the multiple creep characteristic information acquired by the stress analysis unit 24 may include creep rupture curves created by different prediction methods. In this case, the multiple creep characteristic information acquired by the stress analysis unit 24 may include one or more of the creep characteristic information including creep rupture curve L1 output from the machine learning model described above, creep characteristic information including creep rupture curve L2 explained using Figure 6, creep characteristic information including creep rupture curve L4 explained using Figure 7, and creep characteristic information including creep rupture curve L6 explained using Figure 8.

[0046] In S304, the stress analysis unit 24 performs a stress analysis of the connection part 14 using the FEM (finite element method) for each of the creep characteristic information sets obtained in S303, based on the creep characteristic information, the operating time of the boiler 2, the operating conditions of the boiler 2, and the three-dimensional shape data and material of the connection part 14. In S304, as a result of the above stress analysis, the stress analysis unit 24 calculates the strain distribution of the connection part 14 at a point in time when the operating time of the boiler 2 corresponding to the length of the above-mentioned fixed period of operation of the boiler 2 has elapsed, for each of the creep characteristic information sets. Also in S304, the calculation value calculation unit 26 calculates the calculated value of the first parameter (the first parameter obtained in S302) for each of the creep characteristic information sets based on the strain distribution of the connection part 14, which is the result of the stress analysis by the stress analysis unit 24. For example, if the expansion rate of the main pipe 6 is obtained as the measured value of the first parameter in S302, then in S304, the calculated value of the expansion rate of the main pipe 6 is calculated as the calculated value of the first parameter based on the strain distribution of the connection part 14 for each of the multiple creep characteristic information sets.

[0047] In S305, the creep characteristic information determination unit 28 compares the calculated value of the first parameter calculated by the calculation value calculation unit 26 for each piece of first creep information with the measured value of the first parameter acquired by the measurement value acquisition unit 20, and determines the calculated value of the first parameter that is closest to the measured value of the first parameter acquired by the measurement value acquisition unit 20 among the calculated values ​​of the first parameter calculated by the calculation value calculation unit 26 for each piece of first creep information. The creep characteristic information determination unit 28 also determines the creep characteristic information used in the stress analysis unit 24 to calculate the determined calculated value (i.e., the calculated value of the first parameter that is closest to the measured value of the first parameter acquired by the measurement value acquisition unit 20 among the calculated values ​​of the first parameter calculated by the calculation value calculation unit 26 for each piece of first creep information) as the creep characteristic information to be used for evaluating the creep damage degree of the connection part 14.

[0048] For example, if the multiple creep characteristic information acquired by the stress analysis unit 24 in S303 consists of creep characteristic information including creep rupture curve L1 output from the machine learning model described above, creep characteristic information including creep rupture curve L2 explained using Figure 6, creep characteristic information including creep rupture curve L4 explained using Figure 7, and creep characteristic information including creep rupture curve L6 explained using Figure 8, then in S304, the stress analysis unit 24 calculates the strain distribution S1 of the connection part 14 using the creep characteristic information including creep rupture curve L1, calculates the strain distribution S2 of the connection part 14 using the creep characteristic information including creep rupture curve L2, calculates the strain distribution S4 of the connection part 14 using the creep characteristic information including creep rupture curve L4, and calculates the strain distribution S6 of the connection part 14 using the creep characteristic information including creep rupture curve L6.

[0049] Then, in S305, the creep characteristic information determination unit 28 determines the calculated value of the first parameter that is closest to the measured value V0 of the first parameter acquired by the measurement value acquisition unit 20, from among the calculated value V1 of the first parameter calculated based on the strain distribution S1, the calculated value V2 of the first parameter calculated based on the strain distribution S2, the calculated value V4 of the first parameter calculated based on the strain distribution S4, and the calculated value V6 of the first parameter calculated based on the strain distribution S6. That is, the creep characteristic information determination unit 28 calculates the difference between each of the above calculated values ​​V1, V2, V4, and V6 and the measured value V0, and determines the calculated value among the calculated values ​​V1, V2, V4, and V6 that has the smallest absolute value of the difference. Furthermore, the creep characteristic information determination unit 28 determines the creep characteristic information used by the stress analysis unit 24 to calculate the determined calculated value (i.e., the calculated value that is closest to the measured value V0 among the calculated values ​​V1, V2, V4, and V6) to be used as creep characteristic information for evaluating the degree of creep damage of the connection part 14.

[0050] In S306, the creep damage evaluation unit 30 evaluates the creep damage of the connection portion 14 between the main pipe 6 and the pipe support 8 based on the creep characteristic information determined by the creep characteristic information determination unit 28. In S306, the creep damage of a location different from the location where the measured value of the first parameter at the connection portion 14 between the main pipe 6 and the pipe support 8 was measured may be evaluated based on the creep characteristic information determined by the creep characteristic information determination unit 28. For example, if the measurement location of the first parameter in S302 is one of the locations Pa, Pb, or Pc in Figure 1 (for example, when measuring the bulging rate of the main pipe 6 at location Pa, when measuring the expansion rate of the pipe support 8 at location Pb, or when measuring the flattening ratio of the pipe support hole 12 at location Pc), S306 may evaluate the creep damage of the area 19 (see Figure 1) around the through hole 10 in the main pipe 6.

[0051] Thus, in the creep damage evaluation method shown in Figure 10, the first parameter relating to the degree of dimensional change of at least one of the main pipe 6 and the pipe support 8 is compared with a calculated value obtained from the results of a stress analysis using creep characteristic information that shows the creep characteristics of the connection part 14 between the main pipe 6 and the pipe support 8, and with a measured value actually measured in the steam piping 4 used for a certain period of time. Based on this comparison, the creep characteristic information used to evaluate the creep damage of the connection part 14 is determined. Therefore, similar to the creep damage evaluation method shown in Figure 4, the creep characteristic information used to evaluate the creep damage of the connection part 14 between the main pipe 6 and the pipe support 8 can be determined considering the actual strength of the connection part 14 between the main pipe 6 and the pipe support 8, and the creep damage of the connection part 14 between the main pipe 6 and the pipe support 8 can be evaluated with high accuracy. Furthermore, in the creep damage evaluation method shown in Figure 10, the creep characteristic information used to evaluate the creep damage of the connection 14 between the main pipe 6 and the pipe support 8 can be selected from among multiple creep characteristic information sets, taking into account the actual strength of the connection 14 between the main pipe 6 and the pipe support 8 to determine the creep characteristic information with the highest prediction accuracy (the creep characteristic information used in the stress analysis by the stress analysis unit 24 to calculate the calculated value closest to the measured value of the first parameter). Therefore, the creep damage of the connection 14 between the main pipe 6 and the pipe support 8 can be evaluated with high accuracy.

[0052] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0053] For example, in some embodiments, the creep characteristic information determined in S305 (creep characteristic information used by the stress analysis unit 24 to calculate the calculated value of the first parameter that is closest to the measured value of the first parameter) may be corrected based on a comparison between the measured value of the first parameter and the calculated value of the first parameter that is closest to the measured value of the first parameter. In this case, for example, if the measured value of the first parameter is greater than the calculated value of the first parameter that is closest to the measured value of the first parameter, it can be inferred that the actual creep rate in the steam pipe 4 where the first parameter was measured is greater than the creep rate obtained from the creep characteristic information. Therefore, the creep characteristic information determination unit 28 corrects the creep rupture curve in the creep characteristic information so that the creep rupture time under the same stress conditions is shortened (the creep rate is increased). Furthermore, if the measured value of the first parameter is smaller than the calculated value of the first parameter that is closest to the measured value of the first parameter, it can be inferred that the actual creep rate in the steam pipe 4 where the first parameter was measured is smaller than the creep rate obtained from the creep characteristic information. Therefore, the creep characteristic information determination unit 28 corrects the creep rupture curve in the creep characteristic information so that the creep rupture time under the same stress conditions becomes longer (the creep rate becomes smaller). The creep characteristic information determination unit 28 determines the corrected creep characteristic information to be used for evaluating the creep damage degree of the connection part 14 between the main pipe 6 and the pipe support 8. In this case, the creep damage degree evaluation unit 30 evaluates the creep damage degree of the connection part 14 between the main pipe 6 and the pipe support 8 based on the creep characteristic information (corrected creep characteristic information) determined by the creep characteristic information determination unit 28.

[0054] Furthermore, in some embodiments, as shown in Figure 11, the steam piping 4 may further include a pipe support 16 (second pipe support) connected to the main pipe 6. In this case, for example, in the creep damage evaluation method described using Figure 4, each step of S101 to S105 is performed as described above (i.e., S101 to S105 are performed targeting the connection portion 14 between the main pipe 6 and the pipe support 8 to obtain the measured and calculated values ​​of the first parameter corresponding to the connection portion 14), and in S106, the creep characteristic information determination unit 28 may determine the corrected creep characteristic information to be used for evaluating the creep damage of the connection portion 18 between the main pipe 6 and the pipe support 16. In S106, if the corrected creep characteristic information is to be used to evaluate the degree of creep damage at the connection 18 between the main pipe 6 and the pipe support 16, then in S107, the creep damage evaluation unit 30 evaluates the degree of creep damage at the connection 18 between the main pipe 6 and the pipe support 16 based on the creep characteristic information (corrected creep characteristic information) determined by the creep characteristic information determination unit 28.

[0055] Furthermore, in the creep damage evaluation method explained using Figure 9, for example, each step from S201 to S205 is performed as described above (i.e., S201 to S205 are performed targeting the connection part 14 between the main pipe 6 and the pipe support 8 to obtain the measured and calculated values ​​of the first parameter corresponding to the connection part 14). If the creep characteristic information determination unit 28 determines in S206 that the absolute value of the difference between the measured and calculated values ​​of the first parameter is less than or equal to a threshold, the creep characteristic information determination unit 28 may determine the creep characteristic information used to calculate the calculated value of the first parameter that satisfies the conditions of S206 as the creep characteristic information to be used to evaluate the creep damage of the connection part 18 between the main pipe 6 and the pipe support 16, and proceed to S208. In this case, in S208, the creep damage evaluation unit 30 evaluates the creep damage of the connection part 18 between the main pipe 6 and the pipe support 16 based on the creep characteristic information determined by the creep characteristic information determination unit 28.

[0056] Furthermore, in the creep damage evaluation method explained using Figure 10, for example, each step of S301 to S304 is performed as described above (i.e., S301 to S304 are performed targeting the connection part 14 between the main pipe 6 and the pipe support 8 to obtain the measured and calculated values ​​of the first parameter corresponding to the connection part 14), and in S305, the creep characteristic information determination unit 28 may determine the creep characteristic information used in the stress analysis unit 24 to calculate the determined calculated value (i.e., the calculated value of the first parameter that is closest to the measured value of the first parameter obtained by the measurement value acquisition unit 20, among the calculated values ​​of the first parameter calculated by the calculation value calculation unit 26 for each piece of first creep information), as the creep characteristic information to be used for evaluating the creep damage of the connection part 18 between the main pipe 6 and the pipe support 16. In this case, in S306, the creep damage evaluation unit 30 evaluates the creep damage degree of the connection part 18 between the main pipe 6 and the pipe support 16 based on the creep characteristic information determined by the creep characteristic information determination unit 28 (i.e., the calculated value of the first parameter that is closest to the measured value of the first parameter acquired by the measurement value acquisition unit 20, among the calculated values ​​of the first parameter calculated by the calculation value calculation unit 26 for each piece of first creep information).

[0057] The contents described in each of the above embodiments can be understood, for example, as follows:

[0058] [1] A method for evaluating the degree of creep damage to a steam pipe according to at least one embodiment of the present disclosure is a method for evaluating the degree of creep damage to a connection portion (for example, one or both of the connection portions 14, 18) between a main pipe (for example, the main pipe 6) and at least one pipe support (for example, one or both of the pipe supports 8, 16) in a steam pipe (for example, the steam pipe 4 described above), The at least one pipe stand includes a first pipe stand (e.g., pipe stand 8) connected to the main pipe, The creep damage evaluation method described above is: A measurement value acquisition step of acquiring a measurement value of a parameter (for example, the first parameter described above) relating to the degree of dimensional change of at least one of the main pipe and the first pipe support due to the use of the steam piping for a certain period of time, A creep characteristic information acquisition step involves acquiring creep characteristic information that shows the creep characteristics of the connection portion between the main pipe and the first pipe support (for example, the connection portion 14 described above), A stress analysis step in which stress analysis is performed on the connection between the main pipe and the first pipe support using the creep characteristic information, A calculation value calculation step in which the calculated values ​​of the parameters are calculated based on the results of the stress analysis of the connection part between the main pipe and the first pipe support, A creep characteristic information determination step, which determines creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the at least one pipe support, based on a comparison of the measured value and the calculated value of the parameter, A creep damage evaluation step, which evaluates the degree of creep damage at the connection between the main pipe and the at least one pipe support based on the creep characteristic information determined in the creep characteristic information determination step, It is equipped with.

[0059] In the creep damage evaluation method for steam piping described in [1] above, the creep characteristic information to be used to evaluate the creep damage is determined based on the comparison between calculated values ​​obtained from stress analysis results using creep characteristic information that shows the creep characteristics of the connection between the main pipe and the first support, and measured values ​​measured in steam piping that has actually been used for a certain period of time, with respect to the degree of dimensional change of at least one of the main pipe and the first support. Here, the measured values ​​of the above parameters measured in steam piping that has actually been used for a certain period of time are values ​​that reflect the heat creep characteristics of the material at the connection between the main pipe and the first support, and are values ​​that reflect the actual strength of the connection between the main pipe and the first support (especially the actual strength of the main pipe). Therefore, by determining the creep characteristic information to be used to evaluate the creep damage of the connection between the main pipe and at least one support based on a comparison between the measured and calculated values ​​of the above parameters, the creep characteristic information to be used to evaluate the creep damage of the connection between the main pipe and at least one support can be determined considering the actual strength of the connection between the main pipe and the first support. Therefore, the degree of creep damage at the connection between the main pipe and at least one pipe support can be evaluated with high accuracy.

[0060] [2] In some embodiments, the method for evaluating the degree of creep damage to steam piping described in [1] above, In the creep characteristic information determination step, the creep characteristic information obtained in the creep characteristic information acquisition step is corrected based on a comparison of the measured value and the calculated value of the parameter, and the corrected creep characteristic information is determined to be the creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the at least one pipe support.

[0061] According to the method for evaluating the degree of creep damage of steam piping described in [2] above, the creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and at least one pipe support can be corrected to creep characteristic information that reflects the actual strength of the connection between the main pipe and the first pipe support. Therefore, the degree of creep damage at the connection between the main pipe and at least one pipe support can be evaluated with high accuracy.

[0062] [3] In some embodiments, the method for evaluating the degree of creep damage to steam piping described in [1] or [2] above, The parameters are the bulging rate of the main pipe (e.g., the bulging rate As described above), the bulging rate of the first pipe support (e.g., the bulging rate Bs described above), the ratio of the bulging rate of the main pipe to the bulging rate of the first pipe support (e.g., As / Bs), or the flattening ratio of the hole in the pipe support of the first pipe support (e.g., the flattening ratio Bf).

[0063] The bulge ratio of the main pipe is a parameter that changes according to the actual strength of the main pipe, and since the first pipe support is constrained to the main pipe, the bulge ratio of the first pipe support and the flattening ratio of the pipe support hole are also parameters that change according to the actual strength of the main pipe. For this reason, as described in [3] above, by adopting the bulge ratio of the main pipe, the bulge ratio of the first pipe support, the ratio of the bulge ratio of the main pipe to the bulge ratio of the first pipe support, or the flattening ratio of the pipe support hole of the first pipe support as the parameters, the actual strength of the connection between the main pipe and the first pipe support (especially the actual strength of the main pipe) can be well reflected in the creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and at least one pipe support. Therefore, the degree of creep damage at the connection between the main pipe and at least one pipe support can be evaluated with high accuracy.

[0064] [4] In some embodiments, in the method for evaluating the degree of creep damage to steam piping described in any of [1] to [3] above, In the creep characteristic information determination step, creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the first pipe support is determined based on a comparison of the measured value and the calculated value of the parameter. In the creep damage evaluation step, the creep damage to the connection between the main pipe and the first pipe support is evaluated based on the creep characteristic information determined in the creep characteristic information determination step.

[0065] According to the method for evaluating the degree of creep damage to steam piping described in [4] above, the degree of creep damage at the connection between the main pipe and the first pipe support can be evaluated with high accuracy.

[0066] [5] In some embodiments, in the method for evaluating the degree of creep damage to steam piping described in any of [4] above, In the creep damage evaluation step, the creep damage is evaluated at a position different from the position where the measured values ​​of the parameters at the connection between the main pipe and the first pipe support were measured (for example, the position of part 19 described above), based on the creep characteristic information determined in the creep characteristic information determination step.

[0067] According to the method for evaluating the degree of creep damage to steam piping described in [5] above, the degree of creep damage at a location different from the location where the measured parameter values ​​at the connection between the main pipe and the first pipe support were measured can be evaluated with high accuracy.

[0068] [6] In some embodiments, the method for evaluating the degree of creep damage to steam piping described in [4] or [5] above, The parameters are the bulging rate of the first pipe support (e.g., the bulging rate As described above), the ratio of the bulging rate of the main pipe to the bulging rate of the first pipe support (e.g., the ratio As / Bs described above), or the flattening ratio of the hole in the pipe support of the first pipe support (e.g., the flattening ratio Bf described above). In the creep damage evaluation step, the creep damage of the main pipe at the connection between the main pipe and the first pipe support is evaluated based on the creep characteristic information determined in the creep characteristic information determination step.

[0069] Since the first pipe support is constrained to the main pipe, the bulge ratio of the first pipe support and the flattening ratio of the pipe support hole are parameters that change according to the actual strength of the main pipe. For this reason, as described in [6] above, by adopting the bulge ratio of the first pipe support, the ratio of the bulge ratio of the main pipe to the bulge ratio of the first pipe support, or the flattening ratio of the pipe support hole of the first pipe support as the parameters, the actual strength of the main pipe at the connection between the main pipe and the first pipe support can be accurately reflected in the creep characteristic information used to evaluate the degree of creep damage to the main pipe at the connection between the main pipe and the first pipe support. Therefore, the degree of creep damage at the connection between the main pipe and the first pipe support can be evaluated with high accuracy.

[0070] [7] In some embodiments, in the method for evaluating the degree of creep damage to steam piping described in any of [1] to [3] above, The at least one pipe stand includes a first pipe stand (e.g., pipe stand 8 described above) connected to the main pipe, and a second pipe stand (e.g., pipe stand 8 adjacent to pipe stand 8 described above) connected to the main pipe. In the creep characteristic information determination step, creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the second pipe support is determined based on a comparison of the measured value and the calculated value of the parameter. In the creep damage evaluation step, the creep damage to the connection between the main pipe and the second pipe support is evaluated based on the creep characteristic information determined in the creep characteristic information determination step.

[0071] According to the method for evaluating the degree of creep damage to steam piping described in [7] above, the degree of creep damage at the connection between the main pipe and the second pipe support, which is provided on the main pipe common to the first pipe support, can be evaluated with high accuracy.

[0072] [8] In some embodiments, the method for evaluating the degree of creep damage to steam piping described in any of [1] to [7] above, The creep characteristic information acquired in the creep characteristic information acquisition step includes the creep rupture curve of the main pipe (for example, the creep rupture curve L1 described above) output from the machine learning model, which is created by inputting the mill sheet information of the main pipe into a machine learning model that has learned the relationship between the mill sheet information of the main pipe and the creep rupture curve.

[0073] According to the creep damage evaluation method for steam piping described in [8] above, by using a machine learning model that has learned the relationship between mill sheet information and creep rupture curves, a creep rupture curve with high predictive accuracy corresponding to the heat of the material at the connection between the main pipe and the first pipe support can be obtained in the creep characteristic acquisition step. This makes it possible to accurately evaluate the creep damage of the main pipe at the connection between the main pipe and at least one pipe support.

[0074] [9] In some embodiments, in the method for evaluating the degree of creep damage to steam piping described in any of [1] to [8] above, The system further includes a correction step in which a creep rupture test is performed on a sample taken from the main pipe, and the creep rupture curve (for example, the average rupture curve L0 described above) relating to the material of the main pipe is corrected based on the results of the creep rupture test. The creep characteristic information acquired in the creep characteristic information acquisition step includes a creep rupture curve (for example, the creep rupture curves L2, L4, or L6 described above) obtained by correcting the creep rupture curve for the material of the main pipe based on the results of the creep rupture test.

[0075] According to the method for evaluating the degree of creep damage to steam piping described in [9] above, the degree of creep damage to the main pipe at the connection between the main pipe and at least one pipe support can be accurately evaluated by correcting the creep rupture curve for the main pipe material based on the results of the creep rupture test.

[0076]

[10] In some embodiments, in the method for evaluating the degree of creep damage to steam piping described in any of [1] to [9] above, In the creep characteristic information acquisition step, a plurality of creep characteristic information indicating the creep characteristics of the connection between the main pipe and the first pipe support is acquired. In the stress analysis step, for each of the creep characteristic information in the plurality of creep characteristic information, the stress analysis of the connection portion is performed using the creep characteristic information. In the calculation step described above, for each of the creep characteristic information in the plurality of creep characteristic information, the calculated value of the parameter is calculated based on the result of the stress analysis of the connection part between the main pipe and the first pipe support. In the creep characteristic information determination step, the calculated value closest to the measured value is determined from among the calculated values ​​calculated for each of the multiple creep characteristic information, and the creep characteristic information used in the stress analysis step to calculate the calculated value closest to the measured value is determined to be the creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the at least one pipe support.

[0077] According to the creep damage evaluation method for steam piping described in

[10] above, the creep characteristic information used to evaluate the creep damage of the connection between the main pipe and at least one pipe support can be determined from among multiple creep characteristic information, taking into account the actual strength of the connection between the main pipe and the first pipe support (the creep characteristic information used in the stress analysis step to calculate the calculated value closest to the measured value of the parameter). Therefore, the creep damage of the connection between the main pipe and at least one pipe support can be evaluated with high accuracy.

[0078]

[11] In some embodiments, the method for evaluating the degree of creep damage to steam piping described in

[10] above, The system further includes a correction step in which the creep characteristic information used in the stress analysis step to calculate the calculated value closest to the measured value is corrected based on a comparison between the measured value and the calculated value closest to the measured value. In the creep damage evaluation step, the creep damage of the connection between the main pipe and the at least one pipe support is evaluated based on the creep characteristic information obtained by correcting the creep characteristic information in the correction step.

[0079] According to the method for evaluating the degree of creep damage of steam piping described in

[11] above, the creep characteristic information with the highest predictive accuracy determined in

[10] above (creep characteristic information used in the stress analysis step to calculate the calculated value closest to the measured value of the parameter) is further corrected based on a comparison between the measured value of the parameter and the calculated value closest to the measured value and used for evaluating the degree of creep damage. Therefore, the degree of creep damage at the connection between the main pipe and at least one pipe support can be evaluated with even greater accuracy.

[0080]

[12] A creep damage evaluation device for steam piping according to at least one embodiment of the present disclosure is A creep damage evaluation device for steam piping (for example, the creep damage evaluation device 100 described above) for evaluating the degree of creep damage at the connection point (for example, one or both of the connection points 14 and 18 described above) between a main pipe (for example, the main pipe 6 described above) and at least one pipe support (for example, one or both of the pipe supports 8 and 16 described above) in steam piping (for example, steam piping 4 described above), The at least one pipe stand includes a first pipe stand (e.g., pipe stand 8) connected to the main pipe, The creep damage evaluation device is, A measurement value acquisition unit (e.g., the measurement value acquisition unit 20 described above) acquires measured values ​​of parameters (e.g., the first parameter described above) relating to the degree of dimensional change of at least one of the main pipe and the first pipe support due to the use of the steam piping for a certain period of time, A stress analysis unit (for example, the stress analysis unit 24 described above) acquires creep characteristic information indicating the creep characteristics of the connection between the main pipe and the first pipe support (for example, the connection 14 described above), and performs stress analysis of the connection between the main pipe and the first pipe support using the creep characteristic information. A calculation value calculation unit (for example, the calculation value calculation unit 26 described above) calculates the calculated values ​​of the parameters based on the results of the stress analysis of the connection part between the main pipe and the first pipe support, A creep characteristic information determination unit (for example, the creep characteristic information determination unit 28 described above) determines creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the at least one pipe support, based on a comparison of the measured values ​​and calculated values ​​of the parameters, A creep damage evaluation unit (for example, the creep damage evaluation unit 30 described above) evaluates the degree of creep damage at the connection between the main pipe and the at least one pipe support based on the creep characteristic information determined by the creep characteristic information determination unit, It is equipped with.

[0081] In the creep damage evaluation device for steam piping described in

[12] above, the creep characteristic information to be used to evaluate the degree of creep damage is determined based on the comparison between calculated values ​​obtained from stress analysis results using creep characteristic information that shows the creep characteristics of the connection between the main pipe and the first pipe support, and measured values ​​measured in steam piping that has actually been used for a certain period of time, with respect to the degree of dimensional change of at least one of the main pipe and the first pipe support. Here, the measured values ​​of the above parameters measured in steam piping that has actually been used for a certain period of time are values ​​that reflect the heat creep characteristics of the material at the connection between the main pipe and the first pipe support, and are values ​​that reflect the actual strength of the connection between the main pipe and the first pipe support (especially the actual strength of the main pipe). Therefore, by determining the creep characteristic information to be used to evaluate the degree of creep damage of the connection between the main pipe and at least one pipe support based on a comparison between the measured values ​​and calculated values ​​of the above parameters, the creep characteristic information to be used to evaluate the degree of creep damage of the connection between the main pipe and at least one pipe support can be determined taking into account the actual strength of the connection between the main pipe and the first pipe support. Therefore, the degree of creep damage at the connection between the main pipe and at least one pipe support can be evaluated with high accuracy. [Explanation of symbols]

[0082] 2: Boiler 4: Steam piping 6: Main pipe 8: Pipe stand 9: Welded section 10: Through hole 12: Pipe base hole 14: Connection part 20: Measurement value acquisition unit 22: Storage section 24: Stress Analysis Department 26: Calculation unit 28: Creep characteristic information determination unit 30: Creep Damage Assessment Unit 91: Processor 92: RAM 93: ROM 94 HDD 95: Bus 96: Input I / F 98: Output I / F 100: Creep damage evaluation device 103: Stress Analysis Department A: Swelling rate Bf: Oblateness Bs :bulge rate Ea: distance Eb: distance Ec: distance L0: Mean fracture curve L1: Creep rupture curve L2: Creep rupture curve L4: Creep rupture curve L6: Creep rupture curve Pa: Measurement position Pb: Measurement position Pc: Measurement position Q1: Intersection Q2: Intersection S1: Distribution S2: Distribution S4: Distribution S6: Distribution V0: Measured value V1: Calculated value V2: Calculated value V4: Calculated value V6: Calculated value d1: Major axis d2: Short diameter

Claims

1. A method for evaluating the degree of creep damage in steam piping, which evaluates the degree of creep damage at the connection between a main pipe and at least one pipe support in steam piping, The at least one pipe stand includes a first pipe stand connected to the main pipe, The creep damage evaluation method described above is: A measurement value acquisition step to acquire measurement values ​​of parameters relating to the degree of dimensional change of at least one of the main pipe and the first pipe support due to the use of the steam piping for a certain period of time, A creep characteristic information acquisition step involves acquiring creep characteristic information that shows the creep characteristics of the connection portion between the main pipe and the first pipe support, A stress analysis step in which stress analysis is performed on the connection between the main pipe and the first pipe support using the creep characteristic information, A calculation value calculation step in which the calculated values ​​of the parameters are calculated based on the results of the stress analysis of the connection part between the main pipe and the first pipe support, A creep characteristic information determination step, which determines creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the at least one pipe support, based on a comparison of the measured value and the calculated value of the parameter, A creep damage evaluation step, in which the creep damage degree of the connection between the main pipe and the at least one pipe support is evaluated based on the creep characteristic information determined in the creep characteristic information determination step, A method for evaluating the degree of creep damage to steam piping, comprising the following features.

2. The creep damage evaluation method for steam piping according to claim 1, wherein in the creep characteristic information determination step, the creep characteristic information obtained in the creep characteristic information acquisition step is corrected based on a comparison of the measured value and the calculated value of the parameter, and the corrected creep characteristic information is determined to be the creep characteristic information used to evaluate the creep damage degree of the connection between the main pipe and the at least one pipe support.

3. The method for evaluating the degree of creep damage to a steam pipe according to claim 1, wherein the parameter is the bulging rate of the main pipe, the bulging rate of the first pipe support, the ratio of the bulging rate of the main pipe to the bulging rate of the first pipe support, or the flattening ratio of the pipe support hole of the first pipe support.

4. In the creep characteristic information determination step, creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the first pipe support is determined based on a comparison of the measured value and the calculated value of the parameter. The creep damage evaluation step for a steam pipe, wherein the creep damage evaluation step evaluates the creep damage of the connection between the main pipe and the first pipe support based on the creep characteristic information determined in the creep characteristic information determination step, as described in claim 1.

5. The creep damage evaluation step for a steam pipe, according to claim 4, further comprising: evaluating the creep damage at a position different from the position where the measured value of the parameter at the connection between the main pipe and the first pipe support was measured, based on the creep characteristic information determined in the creep characteristic information determination step;

6. The parameters are the bulging ratio of the first pipe support, the ratio of the bulging ratio of the main pipe to the bulging ratio of the first pipe support, or the flattening ratio of the hole in the pipe support of the first pipe support. The creep damage evaluation step for steam piping, wherein the creep damage evaluation step evaluates the creep damage of the main pipe at the connection between the main pipe and the first pipe support based on the creep characteristic information determined in the creep characteristic information determination step, as described in claim 4.

7. The at least one pipe stand includes a first pipe stand connected to the main pipe and a second pipe stand connected to the main pipe. In the creep characteristic information determination step, creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the second pipe support is determined based on a comparison of the measured values ​​and calculated values ​​of the parameters. The creep damage evaluation step for a steam pipe, wherein the creep damage evaluation step evaluates the creep damage of the connection between the main pipe and the second pipe support based on the creep characteristic information determined in the creep characteristic information determination step, as described in claim 1.

8. The creep damage evaluation method for steam piping according to claim 1, wherein the creep characteristic information acquired in the creep characteristic information acquisition step includes a creep rupture curve of the main pipe output from a machine learning model obtained by inputting the mill sheet information of the main pipe into a machine learning model that has learned the relationship between the mill sheet information of the main pipe and the creep rupture curve.

9. The system further includes a correction step in which a creep rupture test is performed on a sample taken from the main pipe, and the creep rupture curve relating to the material of the main pipe is corrected based on the results of the creep rupture test. The creep damage evaluation method for steam piping according to claim 1, wherein the creep characteristic information acquired in the creep characteristic information acquisition step includes a creep rupture curve obtained by correcting the creep rupture curve for the material of the main pipe based on the results of the creep rupture test.

10. In the creep characteristic information acquisition step, a plurality of creep characteristic information indicating the creep characteristics of the connection between the main pipe and the first pipe support is acquired. In the stress analysis step, for each of the creep characteristic information in the plurality of creep characteristic information, the stress analysis of the connection portion is performed using the creep characteristic information. In the calculation step described above, for each of the creep characteristic information in the plurality of creep characteristic information, the calculated value of the parameter is calculated based on the result of the stress analysis of the connection part between the main pipe and the first pipe support. The creep damage evaluation method for steam piping according to claim 1, wherein in the creep characteristic information determination step, the calculated value closest to the measured value is determined from among the calculated values ​​calculated for each of the plurality of creep characteristic information, and the creep characteristic information used in the stress analysis step to calculate the calculated value closest to the measured value is determined to be the creep characteristic information used to evaluate the creep damage degree of the connection between the main pipe and the at least one pipe support.

11. The system further includes a correction step in which the creep characteristic information used in the stress analysis step to calculate the calculated value closest to the measured value is corrected based on a comparison between the measured value and the calculated value closest to the measured value. The creep damage evaluation step for a steam pipe, wherein the creep damage evaluation step evaluates the creep damage of the connection between the main pipe and the at least one pipe support based on the creep characteristic information obtained by correcting the creep characteristic information in the correction step, as described in claim 10.

12. A steam piping creep damage evaluation device for evaluating the degree of creep damage at the connection between a main pipe and at least one pipe support in a steam piping system, The at least one pipe stand includes a first pipe stand connected to the main pipe, The creep damage evaluation device is, A measurement value acquisition unit that acquires measurement values ​​of parameters relating to the degree of dimensional change of at least one of the main pipe and the first pipe support due to the use of the steam piping for a certain period of time, A stress analysis unit that acquires creep characteristic information indicating the creep characteristics of the connection between the main pipe and the first pipe support, and performs stress analysis of the connection between the main pipe and the first pipe support using the creep characteristic information, A calculation value calculation unit that calculates the parameter values ​​based on the results of the stress analysis of the connection part between the main pipe and the first pipe support, A creep characteristic information determination unit determines creep characteristic information used to evaluate the degree of creep damage at the connection between the main pipe and the at least one pipe support, based on a comparison of the measured value and the calculated value of the parameter. A creep damage evaluation unit evaluates the degree of creep damage at the connection between the main pipe and the at least one pipe support based on the creep characteristic information determined by the creep characteristic information determination unit, A device for evaluating the degree of creep damage to steam piping, equipped with the following features.

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