A stress check method and device for low-hardness P91 thick-walled pipe fittings

Abstract

The present application provides a stress calibration method and device for low-hardness P91 thick-walled pipe fittings, the method comprising: performing hardness testing on multiple grid points of a target pipe fitting to determine the low-hardness area of ​​the target pipe fitting; determining the center position of the low-hardness area as a sampling position, and performing multiple small punch sampling along the radial direction of the pipe wall of the target pipe fitting at the sampling position. When the sampled target pipe fitting reaches a preset hardness standard, multiple pipe fitting samples are obtained, and the sampling depth is determined; 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 multiple pipe fitting samples at a specific temperature to perform stress calibration on the target pipe fitting. Through the method and device, the stress calibration of the target pipe fitting can be completed accurately and quickly.

Description

Technical Field

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

[0002] Due to its exceptional high-temperature creep strength and excellent weldability, P91 steel has been widely used in numerous high-temperature components, including main steam piping, reheat steam piping and its bypass system, and high-temperature headers, which operate at temperatures exceeding 566°C. Currently, most thermal power plants and nuclear power plants in supercritical units use P91 steel as thick-walled pipe material.

[0003] However, recent inspections have revealed that P91 thick-walled pipe fittings in many power plants exhibit significant low hardness, long before their design service life. This phenomenon has been observed in some units after only a few thousand hours of operation, or even before they have officially entered service. It is noteworthy that this low hardness phenomenon can be further categorized as overall low hardness and localized low hardness. Extensive literature research indicates that when the hardness of P91 pipe fittings falls below 180 HBW, their various mechanical properties significantly degrade, significantly shortening their remaining service life to perhaps only a few thousand hours, posing a significant threat to the safe operation of the units.

[0004] Currently, many power plants typically replace P91 pipe fittings directly or conduct safety assessments if they detect low hardness during maintenance. Direct pipe replacement often results in insufficient spare parts availability, and the reordering and manufacturing cycle is relatively long. This significantly impacts the unit's power generation time and reduces economic efficiency. Furthermore, this approach is somewhat unwise. Analysis of the causes of low hardness in P91 pipe fittings reveals that this is primarily due to improper heat treatment processes during manufacturing, welding, and heat treatment. This low hardness often persists. When this low hardness is shallow, P91 thick-walled pipe fittings can still provide reliable safety performance within their service life. Direct pipe replacement can result in unnecessary waste. Furthermore, this safety assessment often requires cutting and sampling pipes, and the entire testing cycle is lengthy, potentially negatively impacting the unit's power generation efficiency. Therefore, given that pipe replacement is not possible in the short term, how to more accurately and rapidly perform stress checks on P91 pipe fittings and conduct safety assessments based on these results has become a critical technical challenge that needs to be addressed. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a stress calibration 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 the 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 equivalent stress value of the target pipe fitting, and can accurately and quickly complete the stress calibration of the target pipe fitting.

[0006] In a first aspect, an embodiment of the present application provides a stress verification method for a low-hardness P91 thick-walled pipe fitting, the stress verification 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, gridding the target pipe to obtain a plurality of grid points, and performing hardness testing 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 a sampling position, and a small punch is used to perform multiple sampling 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 a sampling depth is determined.

[0010] The equivalent stress value of the target pipe at the sampling depth is calculated based on the thick wall theory and the strength theory. The allowable stress value of the low hardness area is calculated by performing a tensile test on multiple 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 low hardness, including:

[0012] Performing a hardness test 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 at which the first hardness value is less than the preset hardness value as a first measurement position, and perform a hardness test on the target pipe at the first measurement position using a Brinell hardness tester 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] Furthermore, the performing hardness testing on the target pipe at a plurality of the grid points to determine the low hardness area of ​​the target pipe includes:

[0016] Performing a hardness test 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 perform a hardness test on the target pipe at the second measurement position using a Brinell hardness tester to determine a fourth hardness value of the target pipe at the second measurement position;

[0018] The 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 multiple low hardness detection points are connected to obtain the low hardness area of ​​the target pipe.

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

[0020] A hardness calibration 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 a hardness test 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] calibrating the fifth hardness value using the hardness calibration deviation to obtain a calibrated 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 at a specific temperature on a plurality of pipe samples, including:

[0026] Calculating the three-dimensional stress of the target pipe at the sampling depth position 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 minimum 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 so, 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, an 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 a target pipe at a plurality of preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon;

[0036] a low hardness region determining module, configured to, if yes, grid the target pipe to obtain a plurality of grid points, and perform hardness testing on the target pipe at the plurality of grid points to determine the low hardness region of the target pipe;

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

[0038] The stress check module is used to calculate the equivalent stress value of the target pipe at the sampling depth position based on the thick wall theory and the strength theory, and calculate the allowable stress value of the low hardness area by performing a tensile test at a specific temperature on multiple pipe samples 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. 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, which, when executed by a processor, executes the steps of the stress verification method for low-hardness P91 thick-walled pipe fittings as described above.

[0041] An 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 a sampling position, and multiple small punch samplings are performed along the pipe wall radial direction of the target pipe fitting at the sampling position. When the sampled target pipe fitting reaches a 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 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, thereby improving 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 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 fitting and reduce the economic losses caused by replacing the pipe fitting.

[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 given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. 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 relevant drawings can be obtained based on these drawings without paying any 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 showing 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 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 repair welding 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;

[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] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions 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 generally 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 for which protection is claimed, 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 falls within 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] Due to its exceptional high-temperature creep strength and excellent weldability, P91 steel has been widely used in numerous high-temperature components, including main steam piping, reheat steam piping and its bypass system, and high-temperature headers, which operate at temperatures exceeding 566°C. Currently, most thermal power plants and nuclear power plants in supercritical units use P91 steel as thick-walled pipe material.

[0056] However, recent inspections have revealed that P91 thick-walled pipe fittings in many power plants exhibit significant low hardness, long before their design service life. This phenomenon has been observed in some units after only a few thousand hours of operation, or even before they have officially entered service. It is noteworthy that this low hardness phenomenon can be further categorized as overall low hardness and localized low hardness. Extensive literature research indicates that when the hardness of P91 pipe fittings falls below 180 HBW, their various mechanical properties significantly degrade, significantly shortening their remaining service life to perhaps only a few thousand hours, posing a significant threat to the safe operation of the units.

[0057] Research has found that, currently, many power plants typically replace P91 pipe fittings directly or conduct safety assessments if they detect low hardness during maintenance. Direct pipe replacement often results in insufficient spare parts availability, and the reordering and manufacturing cycle is relatively long. This significantly impacts the unit's power generation time and is economically uneconomical. Furthermore, this approach is somewhat unwise. Analysis of the causes of low hardness in P91 pipe fittings reveals that this is primarily due to improper heat treatment processes during manufacturing, welding, and heat treatment. This low hardness often persists to a certain extent. When this low hardness is shallow, P91 thick-walled pipe fittings can still provide reliable safety performance within their service life. Direct pipe replacement can result in unnecessary waste. Furthermore, this safety assessment often requires cutting and sampling pipes, and the entire testing cycle is lengthy, potentially negatively impacting the unit's power generation efficiency. Therefore, given that pipe replacement is not possible in the short term, how to more accurately and rapidly perform stress checks on P91 pipe fittings and conduct safety assessments based on these tests has become a critical technical challenge that needs to be addressed.

[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 in the embodiment of the present application includes:

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

[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, and a temperature of 566°C is used as the target pipe fitting. It should be noted here 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 life. 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 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. Regarding 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, performing hardness testing on the target pipe at a plurality of preset measurement positions of the target pipe to determine whether the target pipe has low hardness includes:

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

[0065] Regarding the above step 1011, during specific implementation, a portable Leeb hardness tester is used to perform surface hardness testing on the target pipe at each preset measurement position to determine a first hardness value of the target pipe at each preset measurement 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 perform a hardness test on the target pipe at the first measurement position using a Brinell hardness tester 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, which is not specifically limited in this application.

[0068] Regarding step 1012, in a specific implementation, after determining the first hardness value corresponding to each preset measurement location, a determination is made as to whether a preset measurement location exists where the first hardness value is less than the preset hardness value. If so, the preset measurement location where the first hardness value is less than the preset hardness value is determined as the first measurement location. A portable Brinell hardness tester is then used at the first measurement location to perform a hardness test on the target pipe, thereby determining the second hardness value of the target pipe at the first measurement location.

[0069] Here, according to the stress verification method provided in an 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 calibration deviation is determined based on the second hardness value and the first hardness value of the first measurement location.

[0071] Here, after both the second hardness value and the first hardness value at the first measurement location are measured, a hardness calibration deviation is determined based on the second hardness value and the first hardness value at the first measurement location. For example, if the first hardness value at the first measurement location is 130 HBHLD and the second hardness value is 155 HBW, the difference between the second hardness value and the first hardness value is used as the hardness calibration deviation, i.e., ΔHB = 25 HB.

[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 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 with a second hardness value less than the preset hardness value. If so, it is considered that the target pipe has low hardness.

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

[0075] When low hardness is determined for a target pipe, the low hardness region of the target pipe needs to be determined. Regarding step S102 above, in specific implementation, the target pipe is gridded to obtain multiple grid points. The purpose of gridding the target pipe is to increase the number of hardness testing points. These hardness testing points are arranged in a "grid" pattern with appropriate spacing between them. These points are appropriately set and adjusted based on the specifications of the thick-walled pipe to ensure accurate demarcation of the low hardness region. Hardness testing is then performed on the target pipe at these multiple grid points to determine the low hardness region of the target pipe.

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

[0077] Step 1021 : Perform a hardness test 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.

[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 a 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 perform a hardness test on the target pipe at the second measurement position using a Brinell hardness tester to determine a fourth hardness value of the target pipe at the second measurement position.

[0080] Regarding step 1022, in a specific implementation, after determining the third hardness value corresponding to each grid point, a determination is made as to whether a grid point exists whose third hardness value is less than a 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 location. A portable Brinell hardness tester is then used at the second measurement location to perform a hardness test on the target pipe, and the fourth hardness value of the target pipe at each second measurement location is determined.

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

[0082] In the specific implementation of step 1023, after determining the fourth hardness value corresponding to each second measurement location, a determination is made as to whether a second measurement location exists where the fourth hardness value is less than the preset hardness value. If so, the second measurement location is determined as a low-hardness detection point, thereby determining the specific location of the low-hardness detection point. The outermost low-hardness detection points of the multiple low-hardness detection points are then connected to obtain the low-hardness region of the target pipe.

[0083] Here, 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 this application. Figure 2 As shown, the normal hardness range of thick-walled pipe 1 is Figure 2 In the 1-1 area, the low hardness area of ​​thick-walled pipe 1 is 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 obtaining multiple pipe samples when the target pipe reaches a preset hardness standard after sampling, 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. In the specific implementation of the above step S103, the center position of the low hardness area is determined as the 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. 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 This is 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 represents the pipe sample obtained by small punch sampling. Specifically, the sampling method can refer to the requirements of GB / T29459.1. The pipe sample obtained by small punch sampling is a sheet sample with a sample diameter d≈10mm and a thickness 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 meet the preset hardness standard. If not, continue with the next small punch sampling until the target pipe after sampling meets the preset hardness standard, so as to obtain multiple pipe samples and determine the sampling depth. Figure 5 , Figure 5 This is a schematic diagram of the maximum depth of a small punch sampling position in the low hardness area of ​​a P91 thick-walled pipe provided in an embodiment of the present application. Continuing with the above example, after a total of 10 small punch samplings, it was detected that the sampled target pipe reached the preset hardness standard, and the sampling depth was h = 11mm.

[0088] 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 low hardness is caused by improper heat treatment. Therefore, the entire low hardness area is affected by this improper heat treatment process to the same extent, and therefore the depth of the low hardness 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 a hardness test 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] Regarding step 1031, in a specific implementation, a hardness test is performed on the target pipe at a sampling location of the target pipe using a portable Leeb hardness tester to determine a fifth hardness value of the target pipe at the sampling location. Here, as an example, the fifth hardness value at the sampling location is 155 HB HLD.

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

[0093] In the specific implementation of step 1032, the hardness calibration deviation determined in the above step is used to calibrate the fifth hardness value corresponding to the sampling location to obtain a calibrated fifth hardness value. Continuing with the above example, the hardness calibration deviation determined in the above step is ΔHB = 25HB. This hardness calibration deviation is used to verify the fifth hardness value. Specifically, the fifth hardness value is added to the hardness calibration deviation to obtain a calibrated fifth hardness value of 180 HBW.

[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 step 1033, in a 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, and calculating the allowable stress value of the low hardness area by performing a tensile test at a specific temperature on multiple pipe samples to perform stress verification on the target pipe.

[0097] Regarding the above step S104, in the specific implementation, firstly the equivalent stress σ of the small punch sampling depth position in the low hardness area is measured. 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 : Calculate the three-dimensional stress of the target pipe at the sampling depth according to the thick wall theory.

[0100] Regarding the above step 1041, during specific implementation, 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 at the sampling depth along the circumferential direction of the cylinder, σ 轴 It represents the stress of the target pipe at the sampling depth along the axis of the cylinder, σ 径 Indicates the stress of the target pipe at the sampling depth along the radius of the cylinder. 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: Calculate the equivalent stress value of the target pipe at the sampling depth based on the three-dimensional stress according to the strength theory.

[0104] Regarding 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 step 1041 eq Specifically, the Von Mises strength theory calculation formula is as follows:

[0105]

[0106] Continuing the above example, substituting the triaxial stress into the above formula, the equivalent stress σ at the small punch sampling depth 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. It will not be repeated here.

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

[0109] Regarding 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, with the specific temperature being 566°C, to obtain the tensile yield strength R of each pipe fitting sample. el 566℃ .

[0110] Step 1044 : Determine the allowable stress value of the low hardness region 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 [σ] of the material in the low hardness area of ​​P91 thick-walled pipe fittings t Should be R el t / 1.5.

[0112] Regarding the above step 1044, in the specific implementation, the minimum tensile yield strength is determined from the 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] Furthermore, 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] In the specific implementation of the above steps, after determining the equivalent stress value and allowable stress value, the equivalent stress value is compared with the allowable stress value to conduct a safety assessment of the target pipe fitting and determine whether the target pipe fitting can continue to be used. Specifically, the equivalent stress value at the small punch sampling depth in the low hardness area is compared with the allowable stress value. If the equivalent stress value is less than the allowable stress value, the target pipe fitting is considered to be suitable for continued use. If the equivalent stress value is greater than the allowable stress value, the target pipe fitting is considered unsuitable 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 diagram showing the effect of a P91 thick-walled pipe with a small punch sampling location in a low-hardness area after repair welding, as provided in this embodiment of the application. Of course, further evaluation or assessment of the target pipe is still required after repair welding. This ensures that the target pipe can achieve maximum performance within its safe service life, avoiding power generation losses and pipe waste while also providing sufficient time for the power plant to prepare for the next pipe replacement.

[0117] The embodiment of the present application provides a stress verification method 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 samplings are 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 to perform stress verification on the target pipe fitting.

[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, thereby improving 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 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 fitting and reduce the economic losses caused by replacing the pipe fitting.

[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 includes:

[0120] A low hardness determination module 701 is configured to perform hardness testing on a target pipe at a plurality of preset measurement positions of the target pipe to determine whether the target pipe has low hardness.

[0121] The low hardness region determining module 702 is configured to: if yes, grid the target pipe to obtain a plurality of grid points, and perform hardness testing 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 configured to determine the center of the low-hardness area as a sampling location, perform multiple small punch sampling along the radial direction of the target pipe wall at the sampling location, obtain multiple pipe samples when the sampled target pipe reaches a preset hardness standard, and determine the sampling depth;

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

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

[0125] Performing a hardness test 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 at which the first hardness value is less than the preset hardness value as a first measurement position, and perform a hardness test on the target pipe at the first measurement position using a Brinell hardness tester 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 determining module 702 is used to perform hardness testing on the target pipe at a plurality of grid points to determine the low hardness region of the target pipe, the low hardness region determining module 702 is further used to:

[0129] Performing a hardness test 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 perform a hardness test on the target pipe at the second measurement position using a Brinell hardness tester to determine a fourth hardness value of the target pipe at the second measurement position;

[0131] The 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 multiple low hardness detection points are connected to obtain the low hardness area of ​​the target pipe.

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

[0133] A hardness calibration 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 further configured to determine whether the sampled target pipe meets a preset hardness standard through the following steps:

[0135] Performing a hardness test 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] calibrating the fifth hardness value using the hardness calibration deviation to obtain a calibrated 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 calculate the allowable stress value of the low hardness area by performing a tensile test at a specific temperature on multiple pipe samples, the stress verification module 704 is also used to:

[0139] Calculating the three-dimensional stress of the target pipe at the sampling depth position 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 minimum 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 configured to:

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

[0145] If so, 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 FIG, 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 are specifically implemented in accordance with the method embodiment and will not be described in detail here.

[0149] The embodiment of 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 are specifically implemented in accordance with the method embodiment and will not be described in detail here.

[0150] Those skilled in the art will 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 this 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 merely a logical function division. There may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed may be through some communication interface, indirect coupling or communication connection of devices or units, which may be electrical, mechanical or other forms.

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

[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, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute 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 scope of protection of the present application is not limited thereto. Although the present application has been described in detail with reference to the above-mentioned embodiments, those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above-mentioned embodiments within the technical scope disclosed in the present application, or perform equivalent replacements for some of the technical features thereof. These modifications, changes, or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection 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, gridding the target pipe to obtain a plurality of grid points, and performing hardness testing 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 a sampling position, and a small punch is used to perform multiple sampling 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 a sampling depth is determined. The equivalent stress value of the target pipe at the sampling depth is calculated based on the thick wall theory and the strength theory. The allowable stress value of the low hardness area is calculated by performing a tensile test on multiple 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 low hardness, including: Performing a hardness test 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 at which the first hardness value is less than the preset hardness value as a first measurement position, and perform a hardness test on the target pipe at the first measurement position using a Brinell hardness tester 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 performing hardness testing on the target pipe at the plurality of grid points to determine a low hardness area of ​​the target pipe includes: Performing a hardness test 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 perform a hardness test on the target pipe at the second measurement position using a Brinell hardness tester to determine a fourth hardness value of the target pipe at the second measurement position; The 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 multiple low hardness detection points are connected to obtain the 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 calibration 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 a hardness test 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; calibrating the fifth hardness value using the hardness calibration deviation to obtain a calibrated 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: Calculating the three-dimensional stress of the target pipe at the sampling depth position 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 minimum 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 so, 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 a target pipe at a plurality of preset measurement positions of the target pipe to determine whether the target pipe has a low hardness phenomenon; a low hardness region determining module, configured to, if yes, grid the target pipe to obtain a plurality of grid points, and perform hardness testing on the target pipe at the plurality of grid points to determine the low hardness region of the target pipe; a sampling module, configured to determine the center of the low-hardness area as a sampling location, perform multiple small punch sampling along the radial direction of the wall of the target pipe at the sampling location, obtain multiple pipe samples when the sampled target pipe reaches a preset hardness standard, and determine a sampling depth; The stress check module is used to calculate the equivalent stress value of the target pipe at the sampling depth position based on the thick wall theory and the strength theory, and calculate the allowable stress value of the low hardness area by performing a tensile test at a specific temperature on multiple pipe samples 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. When the electronic device is running, the processor and the memory communicate through the bus. When the processor is running, the machine-readable instructions 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 according to any one of claims 1 to 7 are executed.

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