Stress checking method and device for low-hardness P91 thick-wall pipe fitting

Abstract

The invention provides a stress checking method and device for a low-hardness P91 thick-wall pipe fitting, and the method comprises the steps: carrying out the hardness detection of a plurality of grid points of a target pipe fitting, and determining a low-hardness region of the target pipe fitting; the center position of the low-hardness area is determined as a sampling position, multiple times of small punch sampling are conducted in the sampling position in the radial direction of the pipe wall of the target pipe fitting, when the sampled target pipe fitting reaches the preset hardness standard, multiple pipe fitting samples are obtained, and the sampling depth is determined; according to the thick wall theory and the strength theory, the equivalent stress value of the target pipe fitting at the sampling depth position is calculated, the allowable stress value of the low-hardness area is calculated by conducting a tensile test on the multiple pipe fitting samples at the specific temperature, and stress checking is conducted on the target pipe fitting. Through the method and the device, the stress checking of the target pipe fitting can be accurately and quickly completed.

Description

Technical Field

[0001] The present application relates to the technical field of strength verification of P91 steel thick-walled pipe fittings in the electric power industry, and in particular to a stress verification method and device for low-hardness P91 thick-walled pipe fittings. Background Art

[0002] In view of its excellent high-temperature creep strength and excellent welding performance, P91 steel has been widely used in many high-temperature components, including main steam pipes with temperatures exceeding 566°C, reheat steam pipes and their bypass systems, and high-temperature headers. At present, most thermal power plants and nuclear power plants in supercritical units use P91 steel as thick-walled pipes.

[0003] However, in recent years, it has been found during testing that many power plants' P91 thick-walled pipes have shown significant low hardness long before their designed service life. Some units have shown this phenomenon after only a few thousand hours of operation or even before they have officially started operation. It is worth noting that this low hardness phenomenon can be divided into two types: overall low hardness and local low hardness. A large number of literature studies have shown that when the hardness value of P91 pipe fittings is lower than 180HBW, many of its mechanical properties will drop significantly, and the remaining service life will also be greatly shortened, which may only be a few thousand hours, posing a major threat to the safe operation of the unit.

[0004] At present, if many power plants detect low hardness of P91 pipe fittings during maintenance, they usually replace the pipe fittings directly or conduct safety assessments on them. When directly replacing pipe fittings, the spare parts of the power plant are generally insufficient, and the reordering and production cycle is relatively long, which will seriously affect the power generation time of the unit and have poor economic efficiency. More importantly, the method of directly replacing the pipe is a bit blind. The analysis of the reasons for the low hardness of P91 pipe fittings is mainly due to improper heat treatment process during manufacturing, welding and heat treatment. The low hardness caused by improper heat treatment often has a certain depth. When the depth is shallow, P91 thick-walled pipe fittings still have reliable safety performance within a certain service life. Directly replacing the pipe may cause unnecessary waste. The above safety assessment process often requires cutting pipe sampling, and the entire test cycle is long, which may have an adverse effect on the power generation efficiency of the unit. Therefore, under the premise that the pipe fittings cannot be replaced in the short term, how to complete the stress verification of P91 pipe fittings more accurately and quickly, and conduct safety assessment based on this, has become an important technical problem that needs to be solved urgently. Summary of the invention

[0005] In view of this, the purpose of the present application is to provide a stress verification method and device for low-hardness P91 thick-walled pipe fittings. Through small punch sampling and hardness testing, the depth of the low hardness area of ​​the target pipe fitting can be accurately obtained. At the same time, the allowable stress value of the low hardness area at a characteristic temperature can be accurately obtained through the small punch test. According to the thick wall theory and strength theory, the equivalent stress value of the small punch sampling depth position in the low hardness area can be obtained, which improves the calculation accuracy of the allowable stress value and the equivalent stress value of the target pipe fitting, and can accurately and quickly complete the stress verification of the target pipe fitting.

[0006] In a first aspect, an embodiment of the present application provides a stress check method for a low-hardness P91 thick-walled pipe fitting, the stress check method comprising:

[0007] Performing hardness testing on the target pipe at multiple preset measurement positions of the target pipe to determine whether the target pipe has low hardness;

[0008] If yes, the target pipe is gridded to obtain a plurality of grid points, and hardness testing is performed on the target pipe at the plurality of grid points to determine a low hardness area of ​​the target pipe;

[0009] The center position of the low hardness area is determined as the sampling position, and a plurality of small punch samplings are performed along the radial direction of the pipe wall of the target pipe at the sampling position. When the sampled target pipe reaches a preset hardness standard, a plurality of pipe samples are obtained, and the sampling depth is determined;

[0010] The equivalent stress value of the target pipe at the sampling depth is calculated according to the thick wall theory and the strength theory, and the allowable stress value of the low hardness area is calculated by performing a tensile test on a plurality of pipe samples at a specific temperature to perform stress verification on the target pipe.

[0011] Furthermore, the hardness test of the target pipe is performed at a plurality of preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon, including:

[0012] Performing hardness testing on the target pipe at each preset measuring position using a Leeb hardness tester to determine a first hardness value of the target pipe at each preset measuring position;

[0013] Determine a preset measurement position where the first hardness value is less than the preset hardness value as a first measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the first measurement position to determine a second hardness value of the target pipe at the first measurement position;

[0014] When there is a first measurement position where the second hardness value is smaller than the preset hardness value, it is considered that the target pipe has a low hardness phenomenon.

[0015] Further, the hardness test of the target pipe is performed at a plurality of grid points to determine the low hardness area of ​​the target pipe, including:

[0016] Perform hardness testing on the target pipe at each grid point using a Leeb hardness tester to determine a third hardness value of the target pipe at each grid point;

[0017] Determine a grid point where the third hardness value is less than the preset hardness value as a second measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the second measurement position to determine a fourth hardness value of the target pipe at the second measurement position;

[0018] A second measurement position where the fourth hardness value is less than the preset hardness value is determined as a low hardness detection point, and the outermost low hardness detection points among the plurality of low hardness detection points are connected to obtain a low hardness area of ​​the target pipe.

[0019] Further, after determining the second hardness value of the target pipe at the first measurement position, the stress verification method further includes:

[0020] A hardness check deviation is determined based on the second hardness value and the first hardness value of the first measurement location.

[0021] Furthermore, the following steps are used to determine whether the sampled target pipe meets the preset hardness standard:

[0022] Performing hardness testing on the target pipe at the sampling position using a Leeb hardness tester to determine a fifth hardness value of the target pipe at the sampling position;

[0023] Using the hardness verification deviation to verify the fifth hardness value, to obtain a verified fifth hardness value;

[0024] When the fifth hardness value after verification is greater than or equal to the preset hardness value, it is considered that the sampled target pipe meets the preset hardness standard.

[0025] Furthermore, the equivalent stress value of the target pipe at the sampling depth is calculated according to the thick wall theory and the strength theory, and the allowable stress value of the low hardness area is calculated by performing a tensile test on a plurality of pipe samples at a specific temperature, including:

[0026] Calculate the three-dimensional stress of the target pipe at the sampling depth according to the thick wall theory;

[0027] According to the strength theory, the equivalent stress value of the target pipe at the sampling depth is calculated based on the triaxial stress;

[0028] Conduct a specific temperature tensile test on each pipe fitting sample to obtain the tensile yield strength of each pipe fitting sample;

[0029] The allowable stress value of the low hardness area is determined by using the smallest tensile yield strength among multiple tensile yield strengths and a preset allowable stress value standard.

[0030] Furthermore, after determining the equivalent stress value and the allowable stress value, the stress verification method further includes:

[0031] Determining whether the equivalent stress value is less than the allowable stress value;

[0032] If yes, then determining that the safety assessment result of the target pipe is qualified;

[0033] If not, it is determined that the safety assessment result of the target pipe is unqualified.

[0034] In a second aspect, the embodiment of the present application further provides a stress check device for a low-hardness P91 thick-walled pipe fitting, the stress check device comprising:

[0035] A low hardness judgment module is used to perform hardness detection on the target pipe at multiple preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon;

[0036] A low hardness region determination module is used for, if yes, gridding the target pipe to obtain a plurality of grid points, and performing hardness detection on the target pipe at the plurality of grid points to determine the low hardness region of the target pipe;

[0037] A sampling module, used to determine the center position of the low hardness area as the sampling position, perform multiple small punch sampling along the radial direction of the pipe wall of the target pipe at the sampling position, and obtain multiple pipe samples when the sampled target pipe reaches a preset hardness standard, and determine the sampling depth;

[0038] The stress check module is used to calculate the equivalent stress value of the target pipe at the sampling depth position according to the thick wall theory and the strength theory, and calculate the allowable stress value of the low hardness area by performing a tensile test on a plurality of pipe samples at a specific temperature to perform stress check on the target pipe.

[0039] In a third aspect, an embodiment of the present application further provides an electronic device, comprising: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor and the memory communicate through the bus, and when the machine-readable instructions are executed by the processor, the steps of the stress verification method for low-hardness P91 thick-walled pipe fittings as described above are performed.

[0040] In a fourth aspect, an embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the stress verification method for low-hardness P91 thick-walled pipe fittings as described above are executed.

[0041] The embodiment of the present application provides a stress verification method and device for a low-hardness P91 thick-walled pipe fitting. First, a hardness test is performed on the target pipe fitting at multiple preset measurement positions of the target pipe fitting to determine whether the target pipe fitting has a low hardness phenomenon; if so, the target pipe fitting is gridded to obtain multiple grid points, and the hardness test is performed on the target pipe fitting at the multiple grid points to determine the low hardness area of ​​the target pipe fitting; then, the center position of the low hardness area is determined as the sampling position, and multiple small punch sampling is performed along the radial direction of the pipe wall of the target pipe fitting at the sampling position. When the sampled target pipe fitting reaches the preset hardness standard, multiple pipe fitting samples are obtained, and the sampling depth is determined; finally, the equivalent stress value of the target pipe fitting at the sampling depth position is calculated according to the thick wall theory and the strength theory, and the allowable stress value of the low hardness area is calculated by performing a tensile test on the multiple pipe fitting samples at a specific temperature, so as to perform stress verification on the target pipe fitting.

[0042] The present application can accurately obtain the depth of the low hardness area of ​​the target pipe fitting through small punch sampling and hardness testing, and at the same time, the allowable stress value of the low hardness area at a specified temperature can be accurately obtained through the small punch test. According to the thick wall theory and strength theory, the equivalent stress value of the small punch sampling depth position in the low hardness area can be obtained, which improves the calculation accuracy of the allowable stress value and the equivalent stress value of the target pipe fitting. In addition, the method provided by the present application does not require cutting of the pipe fitting, is easy to operate, and can accurately and quickly complete the stress verification of the target pipe fitting. In this way, the subsequent safety assessment using the verified stress can be more accurate, which can not only extend the cycle of replacing the pipe, but also ensure the safety performance of the pipe fittings and reduce the economic losses caused by replacing the pipe fittings.

[0043] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A flow chart of a stress check method for a low-hardness P91 thick-walled pipe provided in an embodiment of the present application;

[0046] Figure 2 A schematic diagram of the distribution of low hardness areas and small punch sampling positions of a P91 thick-walled pipe provided in an embodiment of the present application;

[0047] Figure 3 A schematic cross-sectional view of a small punch sampling a low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application;

[0048] Figure 4 A schematic longitudinal section diagram of a small punch sampling of a low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application;

[0049] Figure 5 A schematic diagram of the maximum depth of a small punch sampling position in a low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application;

[0050] Figure 6 This is a rendering of the effect of a small punch rod sampling position in a low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application after repair welding;

[0051] Figure 7 A schematic structural diagram of a stress check device for a low-hardness P91 thick-walled pipe provided in an embodiment of the present application;

[0052] Figure 8 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0053] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application usually described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, each other embodiment obtained by those skilled in the art without making creative work belongs to the scope of protection of the present application.

[0054] First, the application scenarios to which this application is applicable are introduced. This application can be applied to the technical field of strength verification of P91 steel thick-walled pipe fittings in the power industry.

[0055] In view of its excellent high-temperature creep strength and excellent welding performance, P91 steel has been widely used in many high-temperature components, including main steam pipes with temperatures exceeding 566°C, reheat steam pipes and their bypass systems, and high-temperature headers. At present, most thermal power plants and nuclear power plants in supercritical units use P91 steel as thick-walled pipes.

[0056] However, in recent years, it has been found during testing that many power plants' P91 thick-walled pipes have shown significant low hardness long before their designed service life. Some units have shown this phenomenon after only a few thousand hours of operation or even before they have officially started operation. It is worth noting that this low hardness phenomenon can be divided into two types: overall low hardness and local low hardness. A large number of literature studies have shown that when the hardness value of P91 pipe fittings is lower than 180HBW, many of its mechanical properties will drop significantly, and the remaining service life will also be greatly shortened, which may only be a few thousand hours, posing a major threat to the safe operation of the unit.

[0057] According to research, at present, if many power plants detect low hardness of P91 pipe fittings during maintenance, they usually directly replace the pipe fittings or conduct safety assessments on them. When directly replacing pipe fittings, the spare parts of the power plant are generally insufficient, and the reordering and production cycle is relatively long, which will seriously affect the power generation time of the unit and have poor economic efficiency. More importantly, the method of directly replacing the pipe is slightly blind. The analysis of the reasons for the low hardness of P91 pipe fittings is mainly due to improper heat treatment process during manufacturing, welding and heat treatment. The low hardness caused by improper heat treatment often has a certain depth. When the depth is shallow, P91 thick-walled pipe fittings still have reliable safety performance within a certain service life. Directly replacing the pipe may cause unnecessary waste. The above safety assessment process often requires cutting pipe sampling, and the entire test cycle is long, which may have an adverse effect on the power generation efficiency of the unit. Therefore, under the premise that the pipe fittings cannot be replaced in the short term, how to complete the stress check of P91 pipe fittings more accurately and quickly, and conduct safety assessment based on this, has become an important technical problem that needs to be solved urgently.

[0058] Based on this, the embodiment of the present application provides a stress verification method for low-hardness P91 thick-walled pipe fittings, which improves the calculation accuracy of the allowable stress value and equivalent stress value of the target pipe fittings, and can accurately and quickly complete the stress verification of the target pipe fittings.

[0059] See also Figure 1 , Figure 1 This is a flow chart of a stress check method for a low-hardness P91 thick-walled pipe provided in an embodiment of the present application. Figure 1 As shown in , the stress verification method provided by the embodiment of the present application includes:

[0060] S101, performing hardness testing on a target pipe at a plurality of preset measuring positions of the target pipe to determine whether the target pipe has a low hardness phenomenon.

[0061] In the embodiment provided in this application, a P91 thick-walled pipe fitting in the main steam pipeline of a power plant with a specification of ID230×40mm, a main steam pressure of 24.2MPa in the pipeline, and a temperature of 566°C is used as the target pipe fitting. Here, it should be noted that the stress verification method provided in the embodiment of this application is also applicable to thick-walled pipe fittings with a relatively short service time, and other thick-walled pipe fittings of the same material can also use the stress verification method provided in this application. The preset measurement position can be specifically set according to the actual detection requirements, and this application does not make specific limitations on this.

[0062] Before stress checking the target pipe, it is first necessary to determine whether the target pipe has low hardness. In the above step S101, in the specific implementation, hardness testing is performed on the target pipe at multiple preset measurement positions to determine whether the target pipe has low hardness.

[0063] Specifically, with respect to the above step S101, the hardness test of the target pipe is performed at a plurality of preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon, including:

[0064] Step 1011: Use a Leeb hardness tester to perform hardness testing on the target pipe at each preset measuring position to determine a first hardness value of the target pipe at each preset measuring position.

[0065] Regarding the above step 1011, in specific implementation, a portable Leeb hardness tester is used to perform surface hardness testing on the target pipe at each preset measuring position to determine a first hardness value of the target pipe at each preset measuring position.

[0066] Step 1012: determine a preset measurement position where the first hardness value is less than the preset hardness value as the first measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the first measurement position to determine a second hardness value of the target pipe at the first measurement position.

[0067] Here, as an optional embodiment, the preset hardness value can be pre-set to 180 HBW, and this application does not make any specific limitation on this.

[0068] With respect to the above step 1012, in the specific implementation, after determining the first hardness value corresponding to each preset measurement position, it is determined whether there is a preset measurement position where the first hardness value is less than the preset hardness value. If so, the preset measurement position where the first hardness value is less than the preset hardness value is determined as the first measurement position. Then, the portable Brinell hardness tester is used to perform hardness testing on the target pipe at the first measurement position to determine the second hardness value of the target pipe at the first measurement position.

[0069] Here, according to the stress verification method provided in the embodiment of the present application, after determining the second hardness value of the target pipe at the first measurement position, the stress verification method further includes:

[0070] A hardness check deviation is determined based on the second hardness value and the first hardness value of the first measurement location.

[0071] Here, after the second hardness value and the first hardness value of the first measurement position are measured, the hardness verification deviation is determined based on the second hardness value and the first hardness value of the first measurement position. As an example, the first hardness value of the first measurement position is detected as 130HBHLD, and the second hardness value is detected as 155HBW. At this time, the difference between the second hardness value and the first hardness value is used as the hardness verification deviation, that is, ΔHB=25HB.

[0072] Step 1013: When there is a first measurement position where the second hardness value is smaller than the preset hardness value, it is considered that the target pipe has a low hardness phenomenon.

[0073] Regarding the above step 1013, in specific implementation, after determining the second hardness value of each first measurement position, it is determined whether there is a first measurement position whose second hardness value is less than the preset hardness value. If so, it is considered that the target pipe has a low hardness phenomenon.

[0074] S102: If yes, the target pipe is gridded to obtain a plurality of grid points, and hardness testing is performed on the target pipe at the plurality of grid points to determine a low hardness area of ​​the target pipe.

[0075] When it is determined that the target pipe has low hardness, it is necessary to determine the low hardness area of ​​the target pipe. For the above step S102, in the specific implementation, the target pipe is gridded to obtain multiple grid points. Here, the purpose of gridding the target pipe is to increase the hardness detection points. The hardness detection points are arranged in a "grid" manner, with moderate spacing between the points, and are appropriately set and adjusted according to the specifications of the thick-walled pipes to ensure accurate division of the low hardness area. Then, the hardness of the target pipe is tested at multiple grid points to determine the low hardness area of ​​the target pipe.

[0076] Specifically, with respect to the above step S102, the hardness test of the target pipe is performed at a plurality of grid points to determine the low hardness area of ​​the target pipe, including:

[0077] Step 1021: Use a Leeb hardness tester to perform hardness testing on the target pipe at each grid point to determine a third hardness value of the target pipe at each grid point.

[0078] Regarding the above step 1021, during specific implementation, a portable Leeb hardness tester is used to perform surface hardness testing on the target pipe at each grid point to determine the third hardness value of the target pipe at each grid point.

[0079] Step 1022: determine the grid point where the third hardness value is less than the preset hardness value as the second measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the second measurement position to determine a fourth hardness value of the target pipe at the second measurement position.

[0080] With respect to the above step 1022, in the specific implementation, after determining the third hardness value corresponding to each grid point, it is determined whether there is a grid point whose third hardness value is less than the preset hardness value. If so, the grid point whose third hardness value is less than the preset hardness value is determined as the second measurement position. Then, the portable Brinell hardness tester is used to perform hardness testing on the target pipe at the second measurement position to determine the fourth hardness value of the target pipe at each second measurement position.

[0081] Step 1023, determining the second measurement position where the fourth hardness value is less than the preset hardness value as a low hardness detection point, and connecting the outermost low hardness detection points among the multiple low hardness detection points to obtain the low hardness area of ​​the target pipe.

[0082] With respect to the above step 1023, in the specific implementation, after determining the fourth hardness value corresponding to each second measurement position, it is determined whether there is a second measurement position whose fourth hardness value is less than the preset hardness value. If so, the second measurement position whose fourth hardness value is less than the preset hardness value is determined as a low hardness detection point, that is, the specific position of the low hardness detection point is determined. Then, the outermost low hardness detection point among the multiple low hardness detection points is connected to obtain the low hardness area of ​​the target pipe.

[0083] Here, please see Figure 2 , Figure 2 This is a schematic diagram of the low hardness area and small punch sampling position distribution of a P91 thick-walled pipe provided in the embodiment of the present application. Figure 2 As shown, the normal hardness range of thick-walled pipe 1 is Figure 2 The 1-1 area in the thick-walled pipe 1 has a low hardness area of Figure 2 In the 1-2 area, Figure 2 In the example provided, the outer surface of the low hardness region 1 - 2 of the thick-walled pipe 1 is relatively regular and rectangular.

[0084] S103, determining the center position of the low hardness area as the sampling position, performing multiple small punch sampling along the radial direction of the pipe wall of the target pipe at the sampling position, and when the sampled target pipe reaches a preset hardness standard, obtaining multiple pipe samples and determining the sampling depth.

[0085] After the low hardness area of ​​the target pipe is determined, the depth of the low hardness area needs to be measured. For the above step S103, in the specific implementation, the center position of the low hardness area is determined as the sampling position, and multiple small punch sampling is performed along the radial direction of the pipe wall of the target pipe at the sampling position. Figure 2 In the example provided, the sampling location is Figure 2 Areas 1-3 in.

[0086] See also Figure 3 and Figure 4 , Figure 3 A schematic cross-sectional view of a small punch sampling of a low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application, Figure 4 A schematic longitudinal section diagram of a small punch sampling of a low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application. Figure 2 As shown, Figure 2 The 2 in the figure indicates the pipe sample obtained by sampling with a small punch. Specifically, the sampling method can refer to the requirements of GB / T29459.1. The pipe sample taken by the small punch is a sheet sample with a sample diameter of d≈10mm and a thickness of δ≈0.5mm.

[0087] After each small punch sampling, the target pipe after sampling needs to be tested for hardness to determine whether the target pipe after sampling can reach the preset hardness standard. If not, continue to perform the next small punch sampling until the target pipe after sampling reaches the preset hardness standard, so as to obtain multiple pipe samples and determine the sampling depth. Figure 5 , Figure 5 A schematic diagram of the maximum depth of a small punch sampling position in a low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application. Continuing with the above example, when a total of 10 small punch samplings are performed, it is detected that the sampled target pipe reaches the preset hardness standard, and the sampling depth is h=11mm.

[0088] Here, it should be noted that the depth of the small punch sampling position is used to reflect the depth of the entire low hardness area, mainly for the following two considerations. First, as described in the background technology, the cause of low hardness is improper heat treatment, so the entire low hardness area is basically affected by this improper heat treatment process to the same extent, so the depth of low hardness produced is also basically the same; second, the small punch sampling position is located in the center of the low hardness area, which can better represent the degree of influence of the entire area.

[0089] Specifically, with respect to the above step S103, the following steps are performed to determine whether the sampled target pipe meets the preset hardness standard:

[0090] Step 1031: Perform hardness testing on the target pipe at the sampling position using a Leeb hardness tester to determine a fifth hardness value of the target pipe at the sampling position.

[0091] In the specific implementation of step 1031, a portable Leeb hardness tester is used to test the hardness of the target pipe at the sampling position of the target pipe to determine the fifth hardness value of the target pipe at the sampling position. Here, as an example, the fifth hardness value at the sampling position is detected to be 155HB HLD.

[0092] Step 1032: Use the hardness calibration deviation to calibrate the fifth hardness value to obtain a calibrated fifth hardness value.

[0093] For the above step 1032, in the specific implementation, the fifth hardness value corresponding to the sampling position is checked using the hardness check deviation determined in the above step to obtain the checked fifth hardness value. Here, continuing the above example, the hardness check deviation determined in the above step is ΔHB=25HB, which is to use the hardness check deviation to check the fifth hardness value, that is, the fifth hardness value is added to the hardness check deviation to obtain the checked fifth hardness value, which is 180HBW.

[0094] Step 1033: When the fifth hardness value after verification is greater than or equal to the preset hardness value, it is considered that the sampled target pipe meets the preset hardness standard.

[0095] Regarding the above step 1033, in the specific implementation, after checking the fifth hardness, it is determined whether the checked fifth hardness value is greater than or equal to the preset hardness value. If so, it is considered that the sampled target pipe meets the preset hardness standard.

[0096] S104, calculating the equivalent stress value of the target pipe at the sampling depth position according to the thick wall theory and the strength theory, calculating the allowable stress value of the low hardness area by performing a tensile test on a plurality of pipe samples at a specific temperature, so as to perform stress check on the target pipe.

[0097] Regarding the above step S104, in the specific implementation, the equivalent stress σ of the small punch sampling depth position in the low hardness area is firstly performed. eq Specifically, the equivalent stress value of the target pipe at the sampling depth is calculated based on the thick wall theory and strength theory. Then the allowable stress value [σ] of the low hardness area is calculated. t Specifically, by performing tensile tests at a specific temperature on multiple pipe samples extracted by a small punch, the allowable stress value in the low hardness area is calculated to complete the stress check of the target pipe.

[0098] Specifically, with respect to the above step S104, the equivalent stress value of the target pipe at the sampling depth is calculated according to the thick wall theory and the strength theory, and the allowable stress value of the low hardness area is calculated by performing a tensile test at a specific temperature on a plurality of pipe samples, including:

[0099] Step 1041, calculating the three-dimensional stress of the target pipe at the sampling depth position according to the thick wall theory.

[0100] In the specific implementation of step 1041, the three-dimensional stress of the target pipe at the sampling depth is calculated according to the thick wall theory. Specifically, the thick wall theory formula is as follows:

[0101]

[0102] Among them, D o Indicates the outer diameter of the target pipe, D i represents the inner diameter of the target pipe, D represents the outer diameter at the sampling depth of the small punch, P represents the working pressure, σ 周 It represents the stress of the target pipe along the circumferential direction of the cylinder at the sampling depth, σ 轴 It represents the stress of the target pipe along the axis of the cylinder at the sampling depth, σ 径 In the example provided in this application, according to the specifications, operating parameters and the depth of the low hardness area of ​​the target pipe, it can be known that D o =310mm, D i =230mm, D=288mm, P=24.2MPa, substituting into the above formula, the three-dimensional stress at the sampling depth of the small punch can be obtained as follows: 周 =63.97MPa,σ 轴 =29.63MPa,σ 径 =-4.70MPa.

[0103] Step 1042: According to the strength theory, the equivalent stress value of the target pipe at the sampling depth is calculated based on the three-dimensional stress.

[0104] For the above step 1042, in the specific implementation, according to the Von Mises strength theory, the equivalent stress value σ of the target pipe at the sampling depth position is calculated based on the three-dimensional stress calculated in the above step 1041 eq Specifically, the Von Mises strength theory calculation formula is as follows:

[0105]

[0106] Continuing with the above example, substituting the triaxial stress into the above formula, the equivalent stress σ at the small punch sampling depth position in the low hardness area can be obtained: eq =59.47MPa.

[0107] Here, it should be noted that in this embodiment, the stress is calculated directly according to the specifications of the target pipe. The outer diameter and wall thickness information of the target pipe can also be obtained through actual measurement, and then the stress is calculated according to the above formula, which will not be repeated here.

[0108] Step 1043, performing a specific temperature tensile test on each pipe fitting sample to obtain the tensile yield strength of each pipe fitting sample.

[0109] For the above step 1043, in the specific implementation, a small punch specific temperature tensile test is performed on each pipe fitting sample to obtain the tensile yield strength of each pipe fitting sample. Here, as an example, a small punch high temperature tensile test is performed on each pipe fitting sample according to the small punch test method specified in GB / T 29459.2, and the specific temperature is 566°C to obtain the tensile yield strength R of each pipe fitting sample. el 566℃ .

[0110] Step 1044, determining the allowable stress value of the low hardness area by using the minimum tensile yield strength among the multiple tensile yield strengths and a preset allowable stress value standard.

[0111] Here, as an example, the preset allowable stress value standard can be the allowable stress value specified in GB / T 16507.1, the allowable stress value of the material in the low hardness area of ​​P91 thick-walled pipe fittings [σ] t Should be R el t / 1.5.

[0112] For the above step 1044, in the specific implementation, the minimum tensile yield strength is determined from multiple tensile yield strengths, and the allowable stress value of the low hardness area is determined using the minimum tensile yield strength and the preset allowable stress value standard. Here, continuing the above example, the minimum tensile yield strength R of the material in the low hardness area is obtained. elmin 566℃ =108.20MPa. According to the provisions on allowable stress values ​​in GB / T 16507.1, the allowable stress value of the low hardness area material of the target pipe in this example is [σ] 566℃ Should be equal to R elmin 566℃ / 1.5, that is, [σ] 566℃ =72.13MPa.

[0113] Further, according to the stress verification method provided in the embodiment of the present application, after determining the equivalent stress value and the allowable stress value, the stress verification method further includes:

[0114] Determine whether the equivalent stress value is less than the allowable stress value; if so, determine that the safety assessment result of the target pipe is qualified; if not, determine that the safety assessment result of the target pipe is unqualified.

[0115] For the above steps, in the specific implementation, after determining the equivalent stress value and the allowable stress value, the equivalent stress value is compared with the allowable stress value to evaluate the safety of the target pipe fitting and determine whether the target pipe fitting can continue to be used. Specifically, the equivalent stress value and the allowable stress value at the sampling depth of the small punch in the low hardness area are compared. If the equivalent stress value is less than the allowable stress value, it is considered that the target pipe fitting can continue to be used. If the equivalent stress value is greater than the allowable stress value, it is considered that the target pipe fitting does not meet the conditions for continued use.

[0116] As an optional embodiment, when the target pipe meets the conditions for continued use after stress verification, the sampling position of the small punch on the target pipe should be repaired by welding. Figure 6 , Figure 6 This is a rendering of the effect of a P91 thick-walled pipe with a small punch sampling position in a low hardness area after repair welding provided in the embodiment of the present application. Of course, the target pipe still needs to be further evaluated or assessed after repair welding. In this way, it can ensure that the target pipe can play the maximum efficiency within the safe service life cycle, which not only avoids the loss of power generation and waste of pipes, but also buys sufficient preparation time for the next replacement of pipes in the power plant.

[0117] The stress verification method for a low-hardness P91 thick-walled pipe provided in an embodiment of the present application comprises the following steps: first, performing a hardness test on the target pipe at multiple preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon; if so, the target pipe is gridded to obtain multiple grid points, and a hardness test is performed on the target pipe at the multiple grid points to determine a low-hardness area of ​​the target pipe; then, the center position of the low-hardness area is determined as a sampling position, and multiple small punch samplings are performed along the radial direction of the pipe wall of the target pipe at the sampling position. When the sampled target pipe reaches a preset hardness standard, multiple pipe samples are obtained, and the sampling depth is determined; finally, the equivalent stress value of the target pipe at the sampling depth is calculated according to the thick wall theory and the strength theory, and the allowable stress value of the low-hardness area is calculated by performing a tensile test on the multiple pipe samples at a specific temperature, so as to perform stress verification on the target pipe.

[0118] The present application can accurately obtain the depth of the low hardness area of ​​the target pipe fitting through small punch sampling and hardness testing, and at the same time, the allowable stress value of the low hardness area at a specified temperature can be accurately obtained through the small punch test. According to the thick wall theory and strength theory, the equivalent stress value of the small punch sampling depth position in the low hardness area can be obtained, which improves the calculation accuracy of the allowable stress value and the equivalent stress value of the target pipe fitting. In addition, the method provided by the present application does not require cutting of the pipe fitting, is easy to operate, and can accurately and quickly complete the stress verification of the target pipe fitting. In this way, the subsequent safety assessment using the verified stress can be more accurate, which can not only extend the cycle of replacing the pipe, but also ensure the safety performance of the pipe fittings and reduce the economic losses caused by replacing the pipe fittings.

[0119] See also Figure 7 , Figure 7 This is a schematic diagram of the structure of a stress check device for a low-hardness P91 thick-walled pipe provided in an embodiment of the present application. Figure 7 As shown in , the stress checking device 700 comprises:

[0120] A low hardness judgment module 701 is used to perform hardness detection on a target pipe at a plurality of preset measurement positions of the target pipe to judge whether the target pipe has a low hardness phenomenon;

[0121] The low hardness region determination module 702 is used for, if yes, gridding the target pipe to obtain a plurality of grid points, and performing hardness detection on the target pipe at the plurality of grid points to determine the low hardness region of the target pipe;

[0122] The sampling module 703 is used to determine the center position of the low hardness area as the sampling position, perform multiple small punch sampling along the radial direction of the pipe wall of the target pipe at the sampling position, and obtain multiple pipe samples when the sampled target pipe reaches a preset hardness standard, and determine the sampling depth;

[0123] The stress check module 704 is used to calculate the equivalent stress value of the target pipe at the sampling depth position according to the thick wall theory and the strength theory, and calculate the allowable stress value of the low hardness area by performing a tensile test on a plurality of pipe samples at a specific temperature to perform stress check on the target pipe.

[0124] Furthermore, when the low hardness judgment module 701 is used to perform hardness detection on the target pipe at multiple preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon, the low hardness judgment module 701 is also used to:

[0125] Performing hardness testing on the target pipe at each preset measuring position using a Leeb hardness tester to determine a first hardness value of the target pipe at each preset measuring position;

[0126] Determine a preset measurement position where the first hardness value is less than the preset hardness value as a first measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the first measurement position to determine a second hardness value of the target pipe at the first measurement position;

[0127] When there is a first measurement position where the second hardness value is smaller than the preset hardness value, it is considered that the target pipe has a low hardness phenomenon.

[0128] Furthermore, when the low hardness region determination module 702 is used to perform hardness detection on the target pipe at a plurality of the grid points to determine the low hardness region of the target pipe, the low hardness region determination module 702 is further used to:

[0129] Perform hardness testing on the target pipe at each grid point using a Leeb hardness tester to determine a third hardness value of the target pipe at each grid point;

[0130] Determine a grid point where the third hardness value is less than the preset hardness value as a second measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the second measurement position to determine a fourth hardness value of the target pipe at the second measurement position;

[0131] A second measurement position where the fourth hardness value is less than the preset hardness value is determined as a low hardness detection point, and the outermost low hardness detection points among the plurality of low hardness detection points are connected to obtain a low hardness area of ​​the target pipe.

[0132] Furthermore, the stress verification device 700 further includes a verification deviation calculation module. After determining the second hardness value of the target pipe at the first measurement position, the verification deviation calculation module is used to:

[0133] A hardness check deviation is determined based on the second hardness value and the first hardness value of the first measurement location.

[0134] Furthermore, the sampling module 703 is also used to determine whether the sampled target pipe meets the preset hardness standard through the following steps:

[0135] Performing hardness testing on the target pipe at the sampling position using a Leeb hardness tester to determine a fifth hardness value of the target pipe at the sampling position;

[0136] Using the hardness verification deviation to verify the fifth hardness value, to obtain a verified fifth hardness value;

[0137] When the fifth hardness value after verification is greater than or equal to the preset hardness value, it is considered that the sampled target pipe meets the preset hardness standard.

[0138] Furthermore, when the stress verification module 704 is used to calculate the equivalent stress value of the target pipe at the sampling depth position according to the thick wall theory and the strength theory, and to calculate the allowable stress value of the low hardness area by performing a tensile test at a specific temperature on a plurality of pipe samples, the stress verification module 704 is also used to:

[0139] Calculate the three-dimensional stress of the target pipe at the sampling depth according to the thick wall theory;

[0140] According to the strength theory, the equivalent stress value of the target pipe at the sampling depth is calculated based on the triaxial stress;

[0141] Conduct a specific temperature tensile test on each pipe fitting sample to obtain the tensile yield strength of each pipe fitting sample;

[0142] The allowable stress value of the low hardness area is determined by using the smallest tensile yield strength among multiple tensile yield strengths and a preset allowable stress value standard.

[0143] Furthermore, the stress verification device 700 further includes a safety assessment module. After determining the equivalent stress value and the allowable stress value, the safety assessment module is used to:

[0144] Determining whether the equivalent stress value is less than the allowable stress value;

[0145] If yes, then determining that the safety assessment result of the target pipe is qualified;

[0146] If not, it is determined that the safety assessment result of the target pipe is unqualified.

[0147] See also Figure 8 , Figure 8 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 8 As shown in , the electronic device 800 includes a processor 810 , a memory 820 and a bus 830 .

[0148] The memory 820 stores machine-readable instructions executable by the processor 810. When the electronic device 800 is running, the processor 810 communicates with the memory 820 via the bus 830. When the machine-readable instructions are executed by the processor 810, the above-mentioned Figure 1 The steps of the stress verification method for low-hardness P91 thick-walled pipe fittings in the method embodiment shown in the figure, and the specific implementation method can be found in the method embodiment, which will not be repeated here.

[0149] The present application also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the computer program can execute the above-mentioned Figure 1 The steps of the stress verification method for low-hardness P91 thick-walled pipe fittings in the method embodiment shown in the figure, and the specific implementation method can be found in the method embodiment, which will not be repeated here.

[0150] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0151] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of devices or units can be electrical, mechanical or other forms.

[0152] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0153] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0154] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application can essentially be embodied in the form of a software product, or in other words, the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0155] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-mentioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A stress check method for low hardness P91 thick-walled pipe fittings, characterized in that: The stress verification method comprises: Performing hardness testing on the target pipe at multiple preset measurement positions of the target pipe to determine whether the target pipe has low hardness; If yes, the target pipe is gridded to obtain a plurality of grid points, and hardness testing is performed on the target pipe at the plurality of grid points to determine a low hardness area of ​​the target pipe; The center position of the low hardness area is determined as the sampling position, and a plurality of small punch samplings are performed along the radial direction of the pipe wall of the target pipe at the sampling position. When the sampled target pipe reaches a preset hardness standard, a plurality of pipe samples are obtained, and the sampling depth is determined; The equivalent stress value of the target pipe at the sampling depth is calculated according to the thick wall theory and the strength theory, and the allowable stress value of the low hardness area is calculated by performing a tensile test on a plurality of pipe samples at a specific temperature to perform stress verification on the target pipe.

2. The stress verification method according to claim 1, characterized in that: The hardness test of the target pipe is performed at a plurality of preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon, including: Performing hardness testing on the target pipe at each preset measuring position using a Leeb hardness tester to determine a first hardness value of the target pipe at each preset measuring position; Determine a preset measurement position where the first hardness value is less than the preset hardness value as a first measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the first measurement position to determine a second hardness value of the target pipe at the first measurement position; When there is a first measurement position where the second hardness value is smaller than the preset hardness value, it is considered that the target pipe has a low hardness phenomenon.

3. The stress verification method according to claim 2, characterized in that: The step of performing hardness testing on the target pipe at a plurality of grid points to determine a low hardness area of ​​the target pipe comprises: Perform hardness testing on the target pipe at each grid point using a Leeb hardness tester to determine a third hardness value of the target pipe at each grid point; Determine a grid point where the third hardness value is less than the preset hardness value as a second measurement position, and use a Brinell hardness tester to perform hardness testing on the target pipe at the second measurement position to determine a fourth hardness value of the target pipe at the second measurement position; A second measurement position where the fourth hardness value is less than the preset hardness value is determined as a low hardness detection point, and the outermost low hardness detection points among the plurality of low hardness detection points are connected to obtain a low hardness area of ​​the target pipe.

4. The stress verification method according to claim 2, characterized in that: After determining the second hardness value of the target pipe at the first measurement position, the stress verification method further includes: A hardness check deviation is determined based on the second hardness value and the first hardness value of the first measurement location.

5. The stress verification method according to claim 4, characterized in that: Use the following steps to determine whether the sampled target pipe meets the preset hardness standard: Performing hardness testing on the target pipe at the sampling position using a Leeb hardness tester to determine a fifth hardness value of the target pipe at the sampling position; Using the hardness verification deviation to verify the fifth hardness value, to obtain a verified fifth hardness value; When the fifth hardness value after verification is greater than or equal to the preset hardness value, it is considered that the sampled target pipe meets the preset hardness standard.

6. The stress verification method according to claim 1, characterized in that: The equivalent stress value of the target pipe at the sampling depth is calculated according to the thick wall theory and the strength theory, and the allowable stress value of the low hardness area is calculated by performing a tensile test at a specific temperature on a plurality of pipe samples, including: Calculate the three-dimensional stress of the target pipe at the sampling depth according to the thick wall theory; According to the strength theory, the equivalent stress value of the target pipe at the sampling depth is calculated based on the triaxial stress; Conduct a specific temperature tensile test on each pipe fitting sample to obtain the tensile yield strength of each pipe fitting sample; The allowable stress value of the low hardness area is determined by using the smallest tensile yield strength among multiple tensile yield strengths and a preset allowable stress value standard.

7. The stress verification method according to claim 1, characterized in that: After determining the equivalent stress value and the allowable stress value, the stress verification method further includes: Determining whether the equivalent stress value is less than the allowable stress value; If yes, then determining that the safety assessment result of the target pipe is qualified; If not, it is determined that the safety assessment result of the target pipe is unqualified.

8. A stress check device for low hardness P91 thick-walled pipe fittings, characterized in that: The stress checking device comprises: A low hardness judgment module is used to perform hardness detection on the target pipe at multiple preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon; A low hardness region determination module is used for, if yes, gridding the target pipe to obtain a plurality of grid points, and performing hardness detection on the target pipe at the plurality of grid points to determine the low hardness region of the target pipe; A sampling module, used to determine the center position of the low hardness area as the sampling position, perform multiple small punch sampling along the radial direction of the pipe wall of the target pipe at the sampling position, and obtain multiple pipe samples when the sampled target pipe reaches a preset hardness standard, and determine the sampling depth; The stress check module is used to calculate the equivalent stress value of the target pipe at the sampling depth position according to the thick wall theory and the strength theory, and calculate the allowable stress value of the low hardness area by performing a tensile test on a plurality of pipe samples at a specific temperature to perform stress check on the target pipe.

9. An electronic device, characterized in that: include: A processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor and the memory communicate through the bus, and the machine-readable instructions are executed by the processor to execute the steps of the stress verification method for low-hardness P91 thick-walled pipe fittings as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the stress verification method for a low-hardness P91 thick-walled pipe fitting as described in any one of claims 1 to 7 are executed.

Images