In-service welding burn-through prediction method and system based on radial stress

Abstract

The invention discloses an in-service welding burn-through prediction method and system based on radial stress, and belongs to the field of pipeline maintenance and repair. In-service welding stress distribution characteristics and a burn-through mechanism are analyzed, it is determined that in-pipe radial pressure starts to be larger than the yield strength of the inner wall of the pipeline as a burn-through critical condition, the pipeline can be burnt through only after the inner wall loses efficacy, and the radial stress value of the inner wall of the pipeline in the in-service welding process is approximately equal to the pressure of a medium in the pipeline; scientific theoretical support is provided for criterion formulation, the prediction method is further simplified on the basis, the relation between the in-pipe medium pressure and the pipeline inner wall yield strength is simplified into a design pressure-critical inner wall peak temperature relation table on the basis of the limiting working condition, a direct judgment method is established, and the prediction accuracy is improved. Engineers can judge whether the burn-through problem needs to be considered or not during construction by directly looking up the table, the critical inner wall peak temperature or the critical burn-through ultimate pressure when burn-through does not occur under the specific working condition is given, and the simplified method has better engineering application value.

Description

Technical Field

[0001] The present invention belongs to the field of pipeline maintenance and emergency repair, and particularly relates to a method and system for predicting in-service welding burn-through based on radial stress. Background Art

[0002] In-service welding repair of B-type sleeves refers to a method of directly welding a casing onto an in-service pipeline in a manner of reducing pressure or not reducing pressure without affecting the normal transportation of the medium inside the pipe, so as to repair the defective pipeline. There are mainly two technical difficulties in in-service welding repair: (1) burn-through; (2) cold crack. Among them, burn-through is the primary problem in in-service welding. The existing burn-through criteria are mainly proposed based on the macroscopic burn-through phenomenon of in-service welding, lacking an understanding of the mechanism, and so far, no generally recognized and quantitative mechanism-integrated safety assessment criterion has been formed, mainly including the minimum wall thickness criterion, the highest inner wall temperature criterion, the remaining strength criterion, and the radial deformation criterion.

[0003] The minimum specific wall thickness criterion is specified by API 1104 standard. The minimum safe wall thickness allowed when using low-hydrogen electrodes and normal welding processes for in-service repair is 6.4 mm. The minimum safe wall thickness value specified in SY-T6554-2019 standard is 12.7 mm. The minimum wall thickness is mainly determined based on a large number of experiments and experiences, lacking unity and theoretical support.

[0004] The highest inner wall temperature criterion is that when the BMI research institute proposed based on the Battelle model and using low-hydrogen electrodes, when the peak temperature of the pipeline inner wall is below 982 °C, burn-through instability generally does not occur easily. When using cellulose electrodes, when the peak inner wall temperature is below 760 °C, burn-through instability generally does not occur easily. However, this criterion lacks a mechanistic explanation and scientific theoretical support, restricting the engineering promotion of the criterion.

[0005] The remaining strength criterion is to equivalently consider the high-temperature molten pool area during in-service welding as a "volume-type defect" at normal temperature, and then quantitatively evaluate the burn-through instability risk based on the ASME B31.8 standard. This criterion only considers the strength loss caused by welding and does not consider the influence of the welding stress field, and the predicted burn-through limit is smaller than the actual value.

[0006] The radial deformation criterion is that when burn-through is about to occur, the inner wall of the pipeline generally forms an outward convex radial deformation. The greater the radial deformation amount, the greater the possibility of burn-through, but it is difficult to quantitatively evaluate the burn-through risk using the radial deformation amount.

[0007] The above criteria lack a profound understanding of the stress distribution characteristics and burn-through mechanism of in-service welding, and do not achieve an organic integration of the mechanism and the burn-through safety criterion, resulting in the fact that no generally recognized and quantitative safety assessment criterion or method has been formed so far, and it is impossible to scientifically explain and quantitatively predict the risk of burn-through. Summary of the Invention

[0008] In view of the above problems, in the first aspect, the present invention proposes a method for predicting in-service welding burn-through based on radial stress, including the following steps:

[0009] Determine the critical conditions for in-service welding burn-through and the stress distribution law according to the steel pipe burn-through process test and numerical simulation analysis; the critical burn-through condition is that the radial pressure inside the pipe starts to be greater than the yield strength of the inner wall of the pipe; the stress distribution law is that the pipe will burn through only after the inner wall fails, and the radial stress value on the inner wall of the pipe during in-service welding is approximately equal to the pressure of the medium inside the pipe;

[0010] Determine the relationship between the pressure of the medium inside the pipe and the radial stress on the inner wall of the pipe according to the critical burn-through condition and the stress distribution law, and establish the relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipe;

[0011] Judge whether the pipeline to be repaired will burn through according to the magnitude relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipe;

[0012] Based on the extreme working conditions, simplify the relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipe into a design pressure - critical inner wall peak temperature relationship table;

[0013] Directly determine whether the in-service welded pipeline needs to consider the burn-through problem according to the design pressure - critical inner wall peak temperature relationship table, and give the critical inner wall peak temperature.

[0014] Furthermore, determining the critical conditions for in-service welding burn-through and the stress distribution law according to the steel pipe burn-through process test and numerical simulation analysis includes the following steps:

[0015] Select the steel pipe specifications, test medium and welding method, and conduct in-service welding process tests on pressurized steel pipes at different medium pressures respectively to obtain the critical process parameters for burn-through under different media;

[0016] Establish a sequential thermo-metallurgical-mechanical coupling model for in-service welding of B-type sleeves, import the performance data of the target pipeline material into the material database framework based on finite elements to establish the target pipeline material database, and conduct numerical simulations based on the test conditions to analyze the stress distribution law during in-service welding;

[0017] Determine the critical conditions for in-service welding burn-through according to the stress distribution law during in-service welding and in combination with the critical burn-through conditions of the in-service welding process test of pressurized steel pipes.

[0018] Furthermore, the selected test pipeline specifications are Φ114mm×4mm, the medium inside the pipe is water, and the welding method is TIG welding.

[0019] Furthermore, the stress distribution law during in-service welding includes the distribution laws and evolution laws of the temperature field, strength field, and stress field.

[0020] Further, the specific method for determining the relationship between the pressure of the medium inside the pipe and the yield strength of the pipe inner wall is as follows:

[0021] Determine whether the pressure of the medium inside the pipe is greater than the yield strength at the pipe inner wall during in-service welding. If the pressure of the medium inside the pipe is greater than the yield strength of the pipe inner wall, burn-through will occur; otherwise, burn-through will not occur.

[0022] Further, during the burn-through process of in-service welding, the strength loss of the pipe wall metal will promote burn-through, and the welding compressive stress will inhibit burn-through; under the extreme working conditions, the inhibitory effect of the welding compressive stress is stronger than the promoting effect of the pipe strength loss, and the safety of the in-service welding repair area is higher than that of the defect-free position far from the welding area, so there is no need to consider the burn-through problem of the in-service welding repair area;

[0023] The extreme working conditions refer to the working conditions when the inhibitory effect of the welding compressive stress is stronger than the promoting effect of the pipe strength loss when the temperature of the pipe inner wall is lower than a certain temperature; wherein, the strength is the full-wall thickness strength of the pipe in the in-service welding repair area.

[0024] Further, based on the extreme working conditions, simplifying the relationship between the pressure of the medium inside the pipe and the yield strength of the pipe inner wall into a design pressure - critical inner wall peak temperature relationship table specifically includes the following steps:

[0025] According to the corresponding relationship between the temperature of the pipe inner wall and the yield strength of the pipe inner wall, draw a temperature - yield strength relationship curve;

[0026] Set the design pressure as the critical burn-through limit pressure. When the yield strength of the pipe inner wall is greater than the design pressure, the safety of the in-service repair position is higher than that of other defect-free pipe body positions, and the construction personnel do not need to consider the pipe burn-through problem at this time;

[0027] Consult the inner wall temperature corresponding to the yield strength in the temperature - yield strength relationship curve to establish a design pressure - inner wall peak temperature relationship table.

[0028] Further, the calculation formula for the design pressure of the pipe at other defect-free pipe body positions is as follows:

[0029] P 设计 =2σ s δD

[0030] In the formula, P 设计 is the design pressure value of the defect-free pipe far from the repair area, and σ s , δ and D are the yield strength, pipe wall thickness and pipe diameter of the defect-free pipe respectively.

[0031] In the second aspect, the present invention proposes an in-service welding burn-through prediction system based on radial stress, including:

[0032] The first determination unit determines the burn-through critical conditions and stress distribution law during in-service welding according to the steel pipe burn-through process test and numerical simulation analysis; the burn-through critical condition is that the radial pressure inside the pipe starts to be greater than the yield strength of the pipe inner wall; the stress distribution law is that the pipe will burn through only after the inner wall fails, and the radial stress value on the pipe inner wall during in-service welding is approximately equal to the pressure of the medium inside the pipe.

[0033] The second determination unit determines the relationship between the pressure of the medium inside the pipe and the radial stress on the pipe inner wall according to the burn-through critical conditions and stress distribution law, and establishes the relationship between the pressure of the medium inside the pipe and the yield strength of the pipe inner wall.

[0034] The judgment unit judges whether the pipeline to be repaired will burn through according to the magnitude relationship between the pressure of the medium inside the pipe and the yield strength of the pipe inner wall.

[0035] The simplification unit simplifies the relationship between the pressure of the medium inside the pipe and the yield strength of the pipe inner wall into a design pressure - critical inner wall peak temperature relationship table based on the extreme working conditions.

[0036] The prediction unit directly determines whether the in-service welding pipeline needs to consider the burn-through problem according to the design pressure - critical inner wall peak temperature relationship table, and gives the critical inner wall peak temperature.

[0037] In a third aspect, the present invention proposes an electronic device, including a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete communication with each other through the communication bus;

[0038] The memory stores a computer program;

[0039] The processor, when executing the program stored in the memory, implements the in-service welding burn-through prediction method based on radial stress.

[0040] In a third aspect, the present invention proposes a computer-readable storage medium, storing a computer program, characterized in that when the computer program is run, it executes the in-service welding burn-through prediction method based on radial stress.

[0041] The beneficial effects of the present invention:

[0042] Based on the profound analysis of the stress distribution characteristics and burn-through mechanism during in-service welding, the present invention proposes two key in-service welding burn-through conditions, that is, the radial stress (absolute value) being greater than the yield strength is the critical condition for the outer convex radial deformation and burn-through of the pipe inner wall; the pipe will burn through only after the inner wall fails, and the radial stress value on the pipe inner wall during in-service welding is approximately equal to the pressure of the medium inside the pipe, realizing the integration of the mechanism and the burn-through safety criterion, and providing a scientific theoretical support for the formulation of the criterion.

[0043] The radial stress burn-through prediction method proposed by the present invention only needs to obtain the radial stress value on the inner wall of the pipeline and the yield strength value of the inner wall of the pipeline during in-service welding, and compare the magnitudes of the two to directly determine whether burn-through will occur, without the need for complex calculations, which further facilitates engineering applications. The present invention further simplifies the prediction method and establishes a direct determination method, namely the look-up table method. Engineering personnel can directly look up the table to determine whether the burn-through problem needs to be considered during construction, and give the critical inner wall peak temperature or critical burn-through limit pressure when burn-through does not occur under specific working conditions. The simplified method has better engineering application value.

[0044] The present invention proposes that the strength loss of the pipe wall metal during the burn-through process of in-service welding will promote burn-through, and the welding compressive stress will inhibit burn-through, and the two act in opposite directions. The in-service repair position is not always the most dangerous position. When the inner wall temperature of the pipeline is relatively low, the inhibitory effect of the welding compressive stress is stronger than the promoting effect of the strength loss, and the safety of this position will be higher than that of the defect-free position far from the welding area. At this time, there is no need to consider the burn-through problem, and this working condition can be used as a direct determination method with a higher safety margin. The direct determination method sets the design pressure as the critical burn-through limit pressure. When the yield strength of the inner wall of the pipeline is greater than the design pressure, the safety of the in-service repair position is higher than that of other defect-free pipe body positions, and construction personnel do not need to consider the burn-through problem of the pipeline at this time. This method can make it more convenient for construction personnel to judge the burn-through problem.

[0045] As needed, the radial stress burn-through prediction method has various extended forms. In existing inventions or research, it is considered that the in-service welding repair position is a relatively dangerous position, and the strength loss caused by welding heat will make this position a weak link, without considering the inhibitory effect of the welding compressive stress on burn-through. The in-service welding radial stress burn-through prediction method points out that when the yield strength of the inner wall of the pipeline is greater than the design pressure of the defect-free pipeline at normal temperature, the safety of the in-service repair position will be higher than that of other defect-free pipe body positions. At this time, there is no need to consider the burn-through problem during the in-service welding of the B-type sleeve, and the critical inner wall peak temperature when burn-through does not need to be considered can be given.

[0046] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained by the structures pointed out in the specification, the claims, and the drawings. Brief Description of the Drawings

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0048] Figure 1 It shows the main flowchart of the radial stress burn-through prediction method based on the in-service welding burn-through mechanism of the B-type sleeve in the embodiment of the present invention;

[0049] Figure 2 It shows the detailed flowchart of the radial stress burn-through prediction method based on the in-service welding burn-through mechanism of the B-type sleeve proposed in the embodiment of the present invention;

[0050] Figure 3 It shows the diagram of the radial deformation evolution law under the action of the internal pressure of the medium in the embodiment of the present invention;

[0051] Figure 4 It shows the comparison diagram of the critical burn-through limit pressure and the yield strength of the inner wall of the pipeline in the embodiment of the present invention, which is used to illustrate the critical conditions of burn-through and the characteristics of stress distribution;

[0052] Figure 5 It shows the curve diagram of the relationship between the temperature and yield strength of the pipe material in the embodiment of the present invention;

[0053] Figure 6 It shows the schematic diagram of the architecture of an electronic device proposed by the present invention. Detailed implementation manners

[0054] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0055] Based on the analysis of the stress distribution characteristics and burn-through behavior of in-service welding burn-through, the present invention gives the critical conditions of in-service welding burn-through, that is, the critical condition for the inner wall of the pipeline to generate convex radial deformation is that the radial stress (absolute value) is greater than the yield strength, which is the fundamental reason for the burn-through instability. Based on this, the present invention proposes a method for predicting in-service welding burn-through based on radial stress, as Figure 1-2 shown, including the following steps:

[0056] S1: Determine the critical conditions for burn-through and the stress distribution law during in-service welding based on steel pipe burn-through process tests and numerical simulation analysis; the critical conditions for burn-through are that the radial pressure inside the pipe begins to be greater than the yield strength of the pipe inner wall; the stress distribution law is that the pipe will burn through only after the inner wall fails, and during in-service welding, the radial stress value on the pipe inner wall is approximately equal to the pressure of the medium inside the pipe.

[0057] The critical conditions for burn-through during in-service welding are that the absolute value of the radial stress is greater than the yield strength, that is, when the absolute value of the radial stress is greater than the yield strength, outward convex radial deformation occurs on the pipe inner wall.

[0058] The stress distribution law is that the pipe will burn through only after the inner wall fails, and during in-service welding, the radial stress value on the pipe inner wall is approximately equal to the pressure of the medium inside the pipe.

[0059] Determining the critical conditions for burn-through and the stress distribution law during in-service welding based on steel pipe burn-through process tests and numerical simulation analysis includes the following steps:

[0060] S11: Select the steel pipe specifications, test medium, and welding method, conduct in-service welding process tests on pressurized steel pipes at different medium pressures, and obtain the critical process parameters for burn-through under different media, providing a reference basis for numerical simulation and determining the critical conditions for burn-through during in-service welding;

[0061] Among them, selecting the steel pipe specifications includes selecting the pipe diameter, wall thickness, and length of the steel pipe, etc.; the test medium is water; the critical process parameters for burn-through under different media include but are not limited to welding current, welding voltage, welding speed, medium pressure, and heat input, etc. In an embodiment of the present invention, the test pipe specifications are selected as Φ114mm×4mm, the medium inside the pipe is water, and the welding method is TIG welding (non-consumable inert gas shielded arc welding).

[0062] S12: Establish a thermo-metallurgical-mechanical sequential coupling model for in-service welding of the B-type sleeve, import the performance data of the target pipe material into the material database framework based on finite elements to establish the target pipe material database, and conduct numerical simulation based on the test conditions to analyze the stress distribution law during in-service welding.

[0063] S13: Determine the critical conditions for burn-through during in-service welding according to the stress distribution law during in-service welding and in combination with the critical burn-through conditions of the in-service welding process test of the pressurized steel pipe.

[0064] S2: Determine the relationship between the pressure of the medium inside the pipe and the radial stress on the pipe inner wall according to the critical conditions for burn-through and the stress distribution law, and establish the relationship between the pressure of the medium inside the pipe and the yield strength of the pipe inner wall.

[0065] Specifically, based on the analysis of burn-through tests and stress distribution characteristics, combined with in-service welding process tests and the analysis of in-service welding temperature fields, strength fields, and stress fields, it is proposed that the pipeline will burn through only after the inner wall of the pipeline fails, and the radial stress value on the inner wall of the pipeline is approximately equal to the pressure of the medium inside the pipe. Furthermore, the relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipeline is established.

[0066] S3: Determine whether the pipeline to be repaired will burn through based on the magnitude relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipeline; if the pressure of the medium inside the pipe is greater than the yield strength of the inner wall of the pipeline, it will cause burn-through, otherwise it will not burn through.

[0067] Because the temperature of the inner wall of the pipeline is very high and difficult to determine during the welding process, different inner wall temperatures correspond to different yield strengths, which are not easy to obtain. Therefore, the present invention simplifies on this basis for convenient engineering application. The specific steps are as follows:

[0068] S4: Based on the extreme conditions, simplify the relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipeline into a design pressure - critical inner wall peak temperature relationship table; the extreme conditions are the conditions where the inhibitory effect of the welding compressive stress is just stronger than the promoting effect of the strength loss when the inner wall temperature of the pipeline is lower than a certain temperature; the strength includes but is not limited to the tensile strength and yield strength of the inner wall of the pipeline. Since the strength loss of the pipe wall metal during in-service welding burn-through will promote burn-through, and the welding compressive stress will inhibit burn-through; and under the extreme conditions, the inhibitory effect of the welding compressive stress is stronger than the promoting effect of the pipeline strength loss. At this time, the safety of the in-service welding repair area is higher than that of the defect-free position far from the welding area, and there is no need to consider the burn-through problem of the in-service welding repair area.

[0069] Specifically, it includes the following steps:

[0070] S41: Draw a temperature - yield strength relationship curve according to the corresponding relationship between the inner wall temperature of the pipeline and the yield strength of the inner wall of the pipeline; specifically, the yield strength of the inner wall of the pipeline to be repaired can be measured through a high-temperature tensile test to obtain the temperature - yield strength relationship curve of the pipe material;

[0071] S42: Set the design pressure as the critical burn-through limit pressure. When the yield strength of the inner wall of the pipeline is greater than the design pressure, the safety of the in-service repair position is higher than that of other pipe body positions without defects, so the burn-through of the pipeline is not considered;

[0072] Calculate the design pressure of the pipeline at normal temperature based on the calculation method of the allowable stress of the pipeline (or Barlow equation):

[0073] P 设计 =2σ s δD

[0074] Wherein, P 设计is the design pressure value of the defect-free pipeline far from the repair area, σ s The pipeline wall thickness δ and pipe diameter D are the yield strength, pipeline wall thickness, and pipe diameter of the defect-free pipeline, respectively.

[0075] S43: Consult the inner wall temperature corresponding to the yield strength in the temperature-yield strength relationship curve, and establish a design pressure-inner wall peak temperature relationship table;

[0076] S5: Directly determine whether the in-service welded pipeline needs to consider the burn-through problem according to the design pressure-critical inner wall peak temperature relationship table, and give the critical inner wall peak temperature. When the temperature is lower than this value, the B-type sleeve does not need to consider the burn-through problem during in-service welding.

[0077] In this embodiment, X65 pipeline steel is taken as the implementation object, and the specific implementation process of the radial stress burn-through prediction method based on the burn-through mechanism of the B-type sleeve during in-service welding is discussed. The in-service welding burn-through process test is carried out as follows, and the specific steps are as follows:

[0078] It is generally considered that if the first surfacing circumferential weld does not burn through during in-service welding, subsequent weld beads will not burn through either. The X65 steel pipe specifications are selected as 114mm×200mm×4mm, the medium inside the pipe is water, the pressure of the medium inside the pipe can be adjusted between 0-10MPa, the welding method is TIG welding, no welding wire is added, and an ABB welding robot is used for stable welding. Table 1 shows the in-service welding burn-through test process parameters.

[0079] Table 1 In-service welding burn-through test process parameters

[0080] Number Current (V) Voltage (A) Heat input (J / mm) Medium pressure (MPa) Evaluation 25I-1 181 14.4 456.12 6.3 Safety 25I-2 191 14.3 477.98 6.3 Safety 25I-3 206 14.2 511.91 6.3 Safety 25I-4 220 18.7 719.95 6.3 Safety 25I-5 235 16.4 674.45 6.3 Burn-through 26K-6 230 15.8 635.95 6.3 Burn-through 24C-1 200 15.4 539.0 8.5 Burn-through 24E-1 201 15.2 534.66 8.5 Burn-through 25F-1 181 15.2 481.46 9.0 Safety 25F-2 191 16.2 541.49 9.0 Burn-through 25G-1 181 16.2 513.14 9.0 Burn-through 25H-1 181 15.8 500.465 9.0 Burn-through

[0081] Establish a thermal-metallurgical-mechanical sequential coupling model for the B-type sleeve during in-service welding and a welding material database, carry out numerical simulations based on the test conditions, and analyze the distribution laws and evolution behaviors of the temperature field, strength field, and stress field during the in-service welding process. The numerical simulation scheme is shown in Table 2.

[0082] Table 2

[0083]

[0084] Taking 24C-1 and 24E-1 as typical analysis cases, at this time the welding current is 200A, and burn-through occurred under the medium pressure of 8.5MPa. As Figure 3 , keeping the welding current of 200A unchanged, gradually increase the medium pressure from 0MPa to 12MPa. The radial deformation mode of the pipeline inner wall gradually changes from the inner convex type to the outer convex type, and 8.5MPa is the critical point for the transformation of the deformation model mode. As Figure 4, at this time, the radial stress on the inner wall of the pipeline is exactly greater than the yield strength of the pipeline, and the magnitude of the radial stress is approximately equal to the pressure of the medium inside the pipe. By summarizing, it can be found that the radial stress (absolute value) being greater than the yield strength is the critical condition for the occurrence of convex radial deformation on the inner wall of the pipeline and the fundamental cause of burn-through. Thus, the critical condition for in-service welding burn-through is determined, and the distribution law of in-service welding stress is incorporated into the prediction method of in-service welding radial stress burn-through.

[0085] Determine the magnitude relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipeline; when the pressure of the medium inside the pipe (or the radial stress on the inner wall of the pipeline) is greater than the yield strength of the inner wall of the pipeline, it will cause the pipeline to burn through, otherwise it will not.

[0086] To further simplify the prediction method of in-service welding radial stress burn-through, it is necessary to simplify the relationship between the pressure of the medium inside the pipe and the yield strength of the inner wall of the pipeline into a design pressure - critical inner wall peak temperature relationship table, including the following steps:

[0087] According to the corresponding relationship between the temperature of the inner wall of the pipeline and the yield strength of the inner wall of the pipeline, draw a temperature - yield strength relationship curve. Specifically, in this embodiment, the high-temperature yield strength of the pipe to be repaired is measured through a high-temperature tensile test to obtain the temperature - yield strength relationship curve of the pipe. The temperature - yield strength relationship curve obtained in this embodiment is as Figure 5 shown. Based on the temperature - yield strength relationship curve, the yield strength at this position under the peak temperature of the inner wall is obtained.

[0088] Set the design pressure as the critical burn-through limit pressure. When the high-temperature yield strength at the inner wall of the pipeline is greater than the design pressure, the safety of the in-service repair position is higher than that of other pipe body positions without defects, so the burn-through of the pipeline is not considered;

[0089] Taking the test pipeline as an example, the outer diameter of the pipeline is 114 mm, the wall thickness is 4 mm, and the yield strength is 416 MPa. The design pressure of the pipeline at normal temperature can be calculated according to the following formula:

[0090] P 设计 =2σ s δD

[0091] The calculated design pressure is about 29 MPa. Based on the radial stress criterion, as long as the yield strength of the inner wall of the pipeline is greater than 29 MPa, burn-through instability will not occur. At this time, by referring to the Figure 5 temperature - yield strength relationship curve, it can be known that the critical inner wall peak temperature for no burn-through instability is about 1000 °C, which is very close to the 982 °C given by the Battle model, providing theoretical and experimental support for the Battle model.

[0092] Establish a table of the relationship between the design pressure and the peak inner wall temperature, consult the temperature-yield strength relationship curve, and give the critical peak inner wall temperature when burn-through instability does not occur.

[0093] Compare the predicted values obtained by the radial stress burn-through prediction method proposed in the present invention with the test values, and the results are shown in Table 3 as follows:

[0094] Table 3

[0095]

[0096] It can be seen that when predicting according to the prediction method proposed in the present invention, the prediction results are not much different from the test values.

[0097] Based on the same inventive concept of the present invention, another exemplary embodiment of the present invention provides an in-service welding burn-through prediction system based on radial stress, including:

[0098] A first determination unit determines the critical conditions for in-service welding burn-through and the stress distribution law according to the steel pipe burn-through process test and numerical simulation analysis; the burn-through critical condition is that the internal radial pressure of the pipe begins to be greater than the yield strength of the pipe inner wall; the stress distribution law is that the pipe will burn through only after the inner wall fails, and during the in-service welding process, the radial stress value on the pipe inner wall is approximately equal to the internal medium pressure of the pipe;

[0099] A second determination unit determines the relationship between the internal medium pressure of the pipe and the radial stress of the pipe inner wall according to the burn-through critical conditions and the stress distribution law, and establishes the relationship between the internal medium pressure of the pipe and the yield strength of the pipe inner wall;

[0100] A judgment unit judges whether the pipeline to be repaired will burn through according to the magnitude relationship between the internal medium pressure of the pipe and the yield strength of the pipe inner wall;

[0101] A simplification unit simplifies the relationship between the internal medium pressure of the pipe and the yield strength of the pipe inner wall into a table of the relationship between the design pressure and the critical peak inner wall temperature based on the extreme working conditions;

[0102] A prediction unit directly determines whether the in-service welded pipeline needs to consider the burn-through problem according to the table of the relationship between the design pressure and the critical peak inner wall temperature, and gives the critical peak inner wall temperature.

[0103] Based on the same inventive concept, another exemplary embodiment of the present invention provides an electronic device. As Figure 6 shown, the electronic device includes at least one processor 601, at least one communication interface 602, at least one memory 603 and at least one communication bus 604; wherein, the processor 601, the communication interface 602 and the memory 603 communicate with each other through the communication bus 604;

[0104] A memory 603 stores a computer program.

[0105] A processor 601, when executing the program stored in the memory 603, implements the described method for predicting in-service welding burn-through based on radial stress.

[0106] Optionally, the communication interface can be the interface of a communication module, such as the interface of a GSM module; the processor may be a processor CPU, or a specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention. The memory may include high-speed RAM memory and may also include non-volatile memory, such as at least one disk memory. Among them, the memory stores a program, and the processor calls the program stored in the memory to execute some or all of the above method embodiments.

[0107] Based on the same inventive concept, an embodiment of the present application also provides a computer-readable storage medium storing a computer program, which, when run, implements some or all of the above method embodiments. Optionally, the storage medium can be a non-transitory computer-readable storage medium. For example, the non-transitory computer-readable storage medium can be ROM, random access memory (RAM), CD-ROM, magnetic tape, floppy disk, and optical data storage devices, etc.

[0108] Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A radial stress-based in-service welding burn-through prediction method, characterized in that: The following steps are involved: According to the steel pipe burn-through process test and numerical simulation analysis, the critical conditions and stress distribution law of in-service welding burn-through are determined; the critical condition for burn-through is that the radial pressure inside the pipe begins to be greater than the yield strength of the inner wall of the pipe; the stress distribution law is that the pipe will burn through only after the inner wall fails, and the radial stress value of the inner wall of the pipe during in-service welding is approximately equal to the medium pressure inside the pipe; Determine the relationship between the medium pressure in the pipe and the radial stress of the inner wall of the pipe according to the critical burn-through condition and the stress distribution law, and establish the relationship between the medium pressure in the pipe and the yield strength of the inner wall of the pipe; Determine whether the pipeline to be repaired will burn through based on the relationship between the medium pressure in the pipeline and the yield strength of the inner wall of the pipeline; Based on the extreme working conditions, the relationship between the medium pressure in the pipe and the yield strength of the inner wall of the pipe is simplified to the relationship table between the design pressure and the critical inner wall peak temperature; According to the design pressure-critical inner wall peak temperature relationship table, it is directly determined whether the in-service welded pipeline needs to consider the burn-through problem, and the critical inner wall peak temperature is given.

2. The in-service welding burn-through prediction method based on radial stress according to claim 1 is characterized in that: Determining the critical conditions and stress distribution law of in-service welding burn-through based on the steel pipe burn-through process test and numerical simulation analysis includes the following steps: Select the steel pipe specifications, test medium and welding method, and conduct in-service welding process tests of pressurized steel pipes under different medium pressures to obtain the critical process parameters for burn-through under different media; A thermal-metallurgical-mechanical sequential coupling model for in-service welding of type B sleeves was established. The performance data of the target pipeline material was imported based on the finite element material database framework to establish a target pipeline material database. Numerical simulation was carried out based on the test conditions to analyze the in-service welding stress distribution law during in-service welding. The critical conditions for in-service welding burn-through are determined according to the in-service welding stress distribution law and in combination with the critical working conditions for burn-through of the in-service welding process test of the pressurized steel pipe.

3. The in-service welding burn-through prediction method based on radial stress according to claim 2 is characterized in that: The test pipe is selected to have a size of Φ114 mm×4 mm, the medium in the pipe is water, and the welding method is non-melting inert gas shielded arc welding.

4. The in-service welding burn-through prediction method based on radial stress according to claim 1 is characterized in that: The in-service welding stress distribution law includes the temperature field, strength field, stress field distribution law and evolution law.

5. The in-service welding burn-through prediction method based on radial stress according to claim 1 is characterized in that: The relationship between the medium pressure in the pipe and the yield strength of the inner wall of the pipe is determined as follows: Determine whether the medium pressure in the pipe is greater than the yield strength of the inner wall of the pipe during in-service welding. If the medium pressure in the pipe is greater than the yield strength of the inner wall of the pipe, it will cause burn-through, otherwise it will not burn-through.

6. The in-service welding burn-through prediction method based on radial stress according to claim 1 is characterized in that: During the in-service welding burn-through process, the strength loss of the pipe wall metal will promote the burn-through, and the welding compressive stress will inhibit the burn-through; under the above-mentioned extreme working conditions, when the inhibitory effect of the welding compressive stress is stronger than the promoting effect of the pipeline strength loss, the safety of the in-service welding repair area is higher than the defect-free position far away from the welding area, and there is no need to consider the burn-through problem of the in-service welding repair area; The extreme operating condition is the operating condition when the temperature of the inner wall of the pipeline is lower than a certain temperature and the inhibitory effect of the welding compressive stress is stronger than the promoting effect of the pipeline strength loss; wherein the strength is the full wall thickness strength of the pipeline in the in-service welding repair area.

7. The in-service welding burn-through prediction method based on radial stress according to claim 6 is characterized in that: Based on the extreme working conditions, simplifying the relationship between the medium pressure in the pipe and the yield strength of the inner wall of the pipe into a design pressure-critical inner wall peak temperature relationship table specifically includes the following steps: According to the corresponding relationship between the inner wall temperature of the pipeline and the yield strength of the inner wall of the pipeline, a temperature-yield strength relationship curve is drawn; The design pressure is set as the critical burn-through limit pressure. When the yield strength of the inner wall of the pipeline is greater than the design pressure, the safety of the in-service repair position is higher than that of other defect-free pipe positions. At this time, the construction personnel do not need to consider the problem of pipeline burn-through. The inner wall temperature corresponding to the yield strength in the temperature-yield strength relationship curve is consulted to establish a design pressure-inner wall peak temperature relationship table.

8. The in-service welding burn-through prediction method based on radial stress according to claim 7 is characterized in that: The calculation formula for the design pressure of the pipeline at other pipe body locations without defects is as follows: P 设计 =2σ s δD Where P 设计 is the design pressure value of the defect-free pipeline far away from the repair area, σ s , δ and D are the yield strength, pipe wall thickness and pipe diameter of the defect-free pipe, respectively.

9. An in-service welding burn-through prediction system based on radial stress, characterized in that: include: The first determination unit determines the critical conditions and stress distribution law of in-service welding burn-through according to the steel pipe burn-through process test and numerical simulation analysis; the critical condition for burn-through is that the radial pressure inside the pipe begins to be greater than the yield strength of the inner wall of the pipe; the stress distribution law is that the pipe will burn through only after the inner wall fails, and the radial stress value of the inner wall of the pipe during in-service welding is approximately equal to the medium pressure inside the pipe; A second determination unit determines the relationship between the medium pressure in the pipe and the radial stress of the inner wall of the pipe according to the critical burn-through condition and the stress distribution law, and establishes the relationship between the medium pressure in the pipe and the yield strength of the inner wall of the pipe; A judgment unit determines whether the pipeline to be repaired will be burned through according to the relationship between the medium pressure in the pipeline and the yield strength of the inner wall of the pipeline; Simplified unit, based on the extreme working condition, simplifies the relationship between the medium pressure in the pipe and the yield strength of the inner wall of the pipe into a design pressure-critical inner wall peak temperature relationship table; The prediction unit directly determines whether the burn-through problem of the in-service welded pipeline needs to be considered according to the design pressure-critical inner wall peak temperature relationship table, and gives the critical inner wall peak temperature.

10. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; a memory storing a computer program; The processor is used to implement the in-service welding burn-through prediction method based on radial stress as described in any one of claims 1-8 when executing the program stored in the memory.

11. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed, the in-service welding burn-through prediction method based on radial stress according to any one of claims 1 to 8 is executed.

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