A method, system, medium and device for determining sleeve weld preheat temperature for type B

Abstract

The present application belongs to the field of natural gas pipeline network, and particularly relates to a B-type sleeve welding preheating temperature determination method, system, medium and equipment. The present application provides a theoretical basis for determining the preheating temperature of in-service pipeline reinforcement welding, solves the problem that the preheating temperature of in-service pipeline reinforcement welding is difficult to accurately determine, and causes the performance deterioration of the joint heat affected zone. The calculation method for determining the preheating temperature of in-service reinforcement B-type sleeve welding of the natural gas pipeline provided by the present application can be used for natural gas pipelines of different specifications, different conveying media, different conveying speeds and different conveying temperatures. The calculation method for determining the preheating temperature of in-service reinforcement B-type sleeve welding of the natural gas pipeline provided by the present application is not only suitable for in-service natural gas pipeline reinforcement, but also suitable for in-service oil pipeline reinforcement, and natural gas and oil pipeline reinforcement during shutdown.

Description

Technical Field

[0001] This invention belongs to the field of natural gas pipeline networks, and particularly relates to a method, system, medium and equipment for determining the preheating temperature of B-type sleeve welding. Background Technology

[0002] Natural gas pipelines are pipelines that transport natural gas (including associated gas from oil fields) from extraction sites or processing plants to urban gas distribution centers or industrial users; they are also called gas transmission pipelines. Using pipelines to transport natural gas is the primary method for large-scale onshore transportation of natural gas, eliminating the need for transshipment via water or land transport, shortening transportation cycles, reducing transportation costs, and improving transportation efficiency. Currently, the diameter of natural gas pipelines is continuously increasing, transportation capacity is significantly improving, and pipeline distances are rapidly increasing. Due to factors such as the increasing service life of some pipelines, corrosion, external interference, and inherent defects in pipeline materials, valve failures and pipeline leaks occur frequently.

[0003] Currently, various types of full-circumferential sleeves are the most important and widely used method for repairing defects in land pipelines. There are generally two types: Type A sleeves and Type B sleeves. Type A sleeves are suitable for repairing defects such as pipe metal loss, arc burns, dents, and cracks in the pipe body or straight welds, but are not suitable for repairing circumferential defects, leaks, or defects that will continue to develop. Type B sleeves are suitable for repairing a variety of defects, including leaks and circumferential defects. The difference between Type A and Type B sleeves is that the end of a Type A sleeve is not welded to the pipeline, while the end of a Type B sleeve must be welded to the pipeline. When using a Type B sleeve to reinforce pipeline defects, cold cracks are prone to occur near the weld point between the sleeve end and the pipeline. This is mainly because during the in-service reinforcement of natural gas pipelines, the natural gas inside the pipeline carries away some of the welding heat, accelerating the cooling rate of the heat-affected zone near the weld, producing a hardened structure. Under the subsequent welding thermal stress, the heat-affected zone cracks.

[0004] To prevent cold cracks in the heat-affected zone (HAZ) during the reinforcement of B-type sleeves in in-service natural gas pipelines, preheating is required when welding the end of the B-type sleeve to the pipeline to slow down the cooling rate of the HAZ. However, the appropriate preheating temperature is crucial for preventing cold cracks on the pipeline surface. If the preheating temperature is too low, the HAZ will cool too quickly, still resulting in cold cracks; if the preheating temperature is too high, the mechanical properties of the pipeline surface material will degrade significantly, affecting the subsequent service life of the natural gas pipeline. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method, system, medium and equipment for determining the preheating temperature of B-type sleeve welding.

[0006] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A method for determining the preheating temperature for welding type B sleeves, comprising:

[0007] By processing the relationship between the preheating temperature and cold crack sensitivity of the preset natural gas pipeline using drawing software, the upper and lower limits of the time during which the material of the in-service B-type sleeve of the preset natural gas pipeline does not produce hardened structure during the cooling process from high temperature to room temperature are obtained. Based on the upper and lower limits of the time, the range of preheating temperature for pipe body reinforcement welding of the in-service B-type sleeve of the preset natural gas pipeline under the condition of no transport fluid is determined.

[0008] Obtain the basic parameters of historical flowing natural gas pipelines, and construct a finite element analysis model based on the basic parameters and the specifications of the pre-set in-service B-type sleeve of the natural gas pipeline to obtain the model to be used;

[0009] Input a preset temperature into the model to be used to obtain the temperature value at each preset position of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined. The preset temperature is determined based on the material tolerance of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined.

[0010] Based on the temperature values, establish the temperature relationship between the temperature values ​​and the preset temperature at each preset location of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline to be preheated at the preheating temperature to be determined.

[0011] The in-service B-type sleeve welding preheating temperature of the natural gas pipeline is obtained by inversely calculating the temperature relationship using the preheating temperature range of the pipe body reinforcement welding.

[0012] The beneficial effects of this invention are: it provides a theoretical basis for determining the preheating temperature of in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature of in-service pipeline reinforcement welding, which leads to performance degradation of the heat-affected zone of the joint. The method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. Furthermore, the method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines.

[0013] Based on the above technical solution, the present invention can be further improved as follows.

[0014] Furthermore, the basic parameters of the historical flowing natural gas pipeline include:

[0015] The thermal conductivity, viscosity, Prandtl number, density, Reynolds number, Nusselt number, heat transfer coefficient, and boundary of the heat-affected zone at the end of the reinforcing sleeve weld of natural gas.

[0016] Furthermore, the process of determining the preheating temperature range for pipe body reinforcement welding of the pre-set type B sleeve of the in-service natural gas pipeline under conditions without fluid transport, based on the upper time limit and the lower time limit, is as follows:

[0017] Input the upper time limit and the lower time limit into the first formula to determine the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline in-service type B sleeve under conditions without fluid transport.

[0018] The first formula is:

[0019] ;

[0020] in, For manual arc welding heat input; T0 represents the thermal conductivity of the natural gas pipeline; T0 represents the preheating temperature range for pipe body reinforcement welding under conditions of no fluid transport; t0 represents the temperature range of the natural gas pipeline under conditions of no fluid transport. 8 / 5 The time limit is defined as either the upper or lower limit. The heat input for manual arc welding refers to the welding voltage multiplied by the welding current multiplied by the welding efficiency, and then divided by the welding speed.

[0021] Another technical solution of the present invention to solve the above-mentioned technical problems is as follows: A system for determining the preheating temperature for welding type B sleeves, comprising:

[0022] The determination module is used to: process the relationship between the preheating temperature and cold crack sensitivity of the preset natural gas pipeline through drawing software, obtain the upper and lower limits of the time during which the material of the in-service B-type sleeve of the preset natural gas pipeline does not produce hardened structure when cooled from high temperature to room temperature, and determine the preheating temperature range of the pipe body reinforcement welding of the in-service B-type sleeve of the preset natural gas pipeline under the condition of no transport fluid based on the upper and lower limits of the time.

[0023] The construction module is used to: obtain the basic parameters of historical flowing natural gas pipelines, and construct a finite element analysis model based on the basic parameters and the specifications of the pre-set in-service B-type sleeve of the natural gas pipeline to obtain the model to be used;

[0024] The input module is used to: input a preset temperature into the model to be used, and obtain the temperature value at each preset position of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined. The preset temperature is determined according to the material tolerance of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined.

[0025] The temperature relationship module is used to: establish a temperature relationship between the temperature value at each preset location and the preset temperature at the boundary of the weld heat-affected zone of the in-service B-type sleeve of the natural gas pipeline to be preheated at the preheating temperature to be determined, based on the temperature value;

[0026] The results module is used to: inversely deduce the preheating temperature of the in-service B-type sleeve of the natural gas pipeline by using the preheating temperature range of the pipe body reinforcement welding to obtain the preheating temperature of the temperature relationship.

[0027] The beneficial effects of this invention are: it provides a theoretical basis for determining the preheating temperature of in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature of in-service pipeline reinforcement welding, which leads to performance degradation of the heat-affected zone of the joint. The method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. Furthermore, the method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines.

[0028] Furthermore, the basic parameters of the historical flowing natural gas pipeline include:

[0029] The thermal conductivity, viscosity, Prandtl number, density, Reynolds number, Nusselt number, heat transfer coefficient, and boundary of the heat-affected zone at the end of the reinforcing sleeve weld of natural gas.

[0030] Furthermore, the process of determining the preheating temperature range for pipe body reinforcement welding of the pre-set type B sleeve of the in-service natural gas pipeline under conditions without fluid transport, based on the upper time limit and the lower time limit, is as follows:

[0031] Input the upper time limit and the lower time limit into the first formula to determine the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline in-service type B sleeve under conditions without fluid transport.

[0032] The first formula is:

[0033] ;

[0034] in, For manual arc welding heat input; T0 represents the thermal conductivity of the natural gas pipeline; T0 represents the preheating temperature range for pipe body reinforcement welding under conditions of no fluid transport; t0 represents the temperature range of the natural gas pipeline under conditions of no fluid transport. 8 / 5 The time limit is defined as either the upper or lower limit. The heat input for manual arc welding refers to the welding voltage multiplied by the welding current multiplied by the welding efficiency, and then divided by the welding speed.

[0035] Another technical solution of the present invention to solve the above-mentioned technical problems is as follows: a storage medium storing instructions, wherein when a computer reads the instructions, the computer executes the method described in any of the above-mentioned methods.

[0036] The beneficial effects of this invention are: it provides a theoretical basis for determining the preheating temperature of in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature of in-service pipeline reinforcement welding, which leads to performance degradation of the heat-affected zone of the joint. The method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. Furthermore, the method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines.

[0037] Another technical solution of the present invention to solve the above-mentioned technical problems is as follows: an electronic device, including the above-mentioned storage medium and a processor that executes the instructions in the above-mentioned storage medium.

[0038] The beneficial effects of this invention are: it provides a theoretical basis for determining the preheating temperature of in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature of in-service pipeline reinforcement welding, which leads to performance degradation of the heat-affected zone of the joint. The method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. Furthermore, the method for calculating the preheating temperature of in-service natural gas pipeline reinforcement using type B sleeves proposed in this invention is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating an embodiment of the method for determining the preheating temperature for welding type B sleeves according to the present invention.

[0040] Figure 2 This is a structural framework diagram provided for an embodiment of the preheating temperature determination system for B-type sleeve welding according to the present invention;

[0041] Figure 3 SHCCT diagram of an X80 pipe provided for an embodiment of a method for determining the preheating temperature for welding a type B sleeve according to the present invention;

[0042] Figure 4 This is a schematic diagram showing the relationship between the temperature difference between the HAZ boundary of a Φ1219×18.4mm pipe and the outer surface of the pipe, and the outer surface temperature of the pipe, provided in an embodiment of the method for determining the preheating temperature for welding a type B sleeve according to the present invention.

[0043] Figure 5 A schematic diagram of the morphology of a Φ1219×18.4 mm X80 pipe B-type sleeve reinforcing annular joint provided in an embodiment of the method for determining the welding preheating temperature of a B-type sleeve according to the present invention;

[0044] Figure 6 This is a schematic diagram of the morphology of a Φ1016×14.6 mm X80 pipe B-type sleeve reinforcement annular joint provided in an embodiment of the method for determining the preheating temperature of B-type sleeve welding according to the present invention. Detailed Implementation

[0045] The principles and features of the present invention are described below. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0046] like Figure 1 As shown, a method for determining the preheating temperature for welding type B sleeves includes:

[0047] By processing the relationship between the preheating temperature and cold crack sensitivity of the preset natural gas pipeline using drawing software, the upper and lower limits of the time during which the material of the in-service B-type sleeve of the preset natural gas pipeline does not produce hardened structure during the cooling process from high temperature to room temperature are obtained. Based on the upper and lower limits of the time, the range of preheating temperature for pipe body reinforcement welding of the in-service B-type sleeve of the preset natural gas pipeline under the condition of no transport fluid is determined.

[0048] Obtain the basic parameters of historical flowing natural gas pipelines, and construct a finite element analysis model based on the basic parameters and the specifications of the pre-set in-service B-type sleeve of the natural gas pipeline to obtain the model to be used;

[0049] Input a preset temperature into the model to be used to obtain the temperature value at each preset position of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined. The preset temperature is determined based on the material tolerance of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined.

[0050] Based on the temperature values, establish the temperature relationship between the temperature values ​​and the preset temperature at each preset location of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline to be preheated at the preheating temperature to be determined.

[0051] The in-service B-type sleeve welding preheating temperature of the natural gas pipeline is obtained by inversely calculating the temperature relationship using the preheating temperature range of the pipe body reinforcement welding.

[0052] In some possible implementations, this invention provides a theoretical basis for determining the preheating temperature for in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature for in-service pipeline reinforcement welding, which leads to performance degradation in the heat-affected zone of the joint. The method for calculating the preheating temperature for welding type B sleeves for in-service natural gas pipeline reinforcement proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. This method is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines.

[0053] It should be noted that the steps involved in the solution are described in further detail below, but the specific determination methods such as the calculation formulas in the solution can be understood by referring to the implementation examples.

[0054] Step 1: By processing the relationship between the preheating temperature and cold crack sensitivity of the natural gas pipeline using plotting software, the upper and lower limits of the time required for the natural gas pipeline material to cool from high temperature to room temperature without producing hardened structures are obtained. Based on the upper and lower limits of the time, the specific implementation process of determining the preheating temperature range for pipe body reinforcement welding of the natural gas pipeline under conditions without transporting fluid is as follows:

[0055] Analysis of the relationship between preheating temperature and cold crack susceptibility of natural gas pipelines. Using JMatPro software (i.e., plotting software), a continuous cooling transformation diagram (SHCCT diagram) for welding of metal materials used in natural gas pipelines was plotted. The critical temperature (t) at which the pipeline material does not produce a hardened structure when cooled from high temperature to room temperature was analyzed from the diagram. 8 / 5 Time, and then based on t 8 / 5 The relationship between time and preheating temperature determines the range of preheating temperatures for pipe reinforcement welding of natural gas pipelines under conditions without transporting fluid.

[0056] Establish the relationship between t8 / 5 time and preheating temperature based on (Formula 1):

[0057] (Formula 1)

[0058] In the formula, : Heat input for manual arc welding (J / cm);

[0059] Thermal conductivity (W / (cm·℃));

[0060] T0: Preheating temperature (°C).

[0061] Note that the critical t 8 / 5 Time has both an upper and lower limit, t 8 / 5 The lower limit is the CCT diagram of the metal material to be welded. The corresponding time, t 8 / 5 The upper limit is the CCT diagram of the metal material to be welded. The corresponding time.

[0062] Step 2: Obtain the basic parameters of the historical flowing natural gas pipeline, and construct a finite element analysis model based on the basic parameters and the specifications of the pre-set in-service Type B sleeve of the natural gas pipeline. The specific implementation process of the model to be used is as follows:

[0063] Calculation of the thermal conductivity of flowing natural gas. Since natural gas is a mixture, it is necessary to determine the composition and content of the natural gas within the pipeline, and then consult relevant data to obtain the thermal conductivity of each component at different temperatures. The thermal conductivity of natural gas is calculated using the formula for calculating the thermal conductivity of mixed gases. As natural gas is a mixture, its thermal conductivity changes with variations in its components and their content; furthermore, the thermal conductivity of the same component and content of natural gas differs at different temperatures and atmospheric pressures.

[0064] Viscosity calculation of flowing natural gas. The viscosity of each component of natural gas at different temperatures was obtained from relevant literature. The viscosity of natural gas was then calculated using the formula for calculating the viscosity of mixed gases. Natural gas is a mixture; its Prandtl number changes with the composition and content of each component. Furthermore, the Prandtl number of natural gas with the same composition and content varies at different temperatures and atmospheric pressures.

[0065] Prandtl number calculation for flowing natural gas. The isobaric specific heat capacity of each component of natural gas at different temperatures was obtained from relevant literature. The isobaric specific heat capacity of natural gas was then calculated using the formula for calculating the isobaric specific heat capacity of a mixed gas. Subsequently, the thermal conductivity, viscosity, and isobaric specific heat capacity of natural gas obtained from the previous steps were substituted into the Prandtl number calculation formula to calculate the Prandtl number. Since natural gas is a mixture, its Prandtl number changes as its components and their content vary. Furthermore, the Prandtl number of natural gas with the same component and content differs at different temperatures and atmospheric pressures.

[0066] Density calculation of flowing natural gas. The density of each component of natural gas at different temperatures was obtained from relevant literature. The density of natural gas was then calculated using the formula for calculating the density of mixed gases. Natural gas is a mixture; its density changes as its components and their content change. Furthermore, the density of natural gas with the same component and content varies at different temperatures and atmospheric pressures.

[0067] Calculation of the Reynolds number for flowing natural gas. The flow rate of the flowing natural gas... v Pipe diameter dThe density ρ and the viscosity μ of natural gas are substituted into the Reynolds number calculation formula to calculate the Reynolds number of natural gas. Natural gas is a mixture, and its Reynolds number changes when the components of natural gas and the content of each component change. Moreover, the Reynolds number of natural gas with the same components and content is different at different temperatures and atmospheric pressures.

[0068] Calculation of the Nusselt number of flowing natural gas. (This refers to the calculation of the Reynolds number of the natural gas.) Re And Prandtl Pr Substitute the components into the Nusselt number calculation formula to calculate the Nusselt number of natural gas. Natural gas is a mixture, and its Nusselt number changes when the components and the content of each component change. Furthermore, the Nusselt number of natural gas with the same components and content is different at different temperatures and atmospheric pressures.

[0069] Calculation of the heat transfer coefficient of flowing natural gas. The Nusselt number of the natural gas is used. The thermal conductivity λ is substituted into the heat exchange coefficient calculation formula to calculate the heat exchange coefficient of natural gas. Natural gas is a mixture, and its heat exchange coefficient changes when the components of natural gas and the content of each component change. Moreover, the heat exchange coefficient of natural gas with the same component and content is different at different temperatures and atmospheric pressures.

[0070] Calculation of the heat-affected zone (HAZ) boundary at the end of the reinforcing sleeve. According to relevant theories of welding metallurgy, the temperature range of the HAZ during welding is between 727℃ and Ac3. Using 727℃ as the boundary temperature of the HAZ, the width of the HAZ during reinforcing welding is calculated using the formula. The effect of preheating on the width of the HAZ is not considered; this width is an estimate.

[0071] Calculate the width of the heat-affected zone according to (Formula 2):

[0072] T max = (Formula 2)

[0073] In the formula, Welding line energy, J / cm;

[0074] Specific heat ;

[0075] density, ;

[0076] Its value is 2.718;

[0077] Its value is 3.14;

[0078] r represents the width of the heat-affected zone.

[0079] Step 3: Input the preset temperature into the model to be used to obtain the temperature value of the weld heat-affected zone boundary of the in-service natural gas pipeline for which the preheating temperature is to be determined. The specific implementation process of the preset temperature being determined based on the material of the in-service natural gas pipeline for which the preheating temperature is to be determined is as follows:

[0080] The preset temperature is the temperature applied to the circumferential weld between the sleeve and the pipe.

[0081] A finite element analysis model of the in-service natural gas pipeline was established in ANSYS Workbench software based on its specifications (including outer diameter, wall thickness, and material). This model needed to be consistent with the dimensions of the natural gas pipeline to be reinforced and the sleeve. Considering that the strength and toughness of most metallic materials (especially X80 pipelines) decrease significantly when heated to above 400°C and cooled to room temperature, two temperature points below 400°C (390°C and 150°C are recommended) were first selected in the finite element model for preheating simulation to obtain the HAZ boundary temperature for the root pass weld and the outer surface temperature of the pipeline. In the finite element analysis of the preheating temperature field of the in-service natural gas pipeline, the ratio of the finite element analysis calculation model to the actual pipeline size was 1:1, and the ratio of the finite element preheating region to the actual preheating region was also 1:1. During the finite element analysis of the preheating temperature field of the in-service natural gas pipeline, the thermal radiation coefficient of the pipeline's outer surface was 0.6, and the convective heat transfer coefficient was 0.000005. When performing finite element analysis on the preheating temperature field of in-service oil pipelines or other fluid medium pipelines, the thermal radiation coefficient and convective heat transfer coefficient of the pipeline's outer surface need to be determined through experimental measurement or a combination of experimental and finite element calculations.

[0082] Step 4, establishing the temperature relationship of the weld heat-affected zone boundary of the in-service natural gas pipeline with the preheating temperature to be determined based on the temperature value, wherein the temperature relationship is the relationship between the temperature value and the temperature difference of the pipeline's outer surface, the specific implementation process is as follows:

[0083] Establish the relationship between the temperature difference between the HAZ boundary and the outer surface of the pipe and the temperature of the outer surface of the pipe (in Origin software, fitting two sets of temperatures (390℃ and its corresponding heat-affected zone boundary temperature, 150℃ and its corresponding heat-affected zone boundary temperature) can yield a fitting curve or fitting formula, thus obtaining the heat-affected zone boundary temperature value corresponding to any preheating temperature). The temperature at the HAZ boundary must be at t 8 / 5 Based on the principle of the preheating temperature range corresponding to the time, the preheating temperature range of the pipeline can be deduced.

[0084] Step 5, the specific implementation process of obtaining the preheating temperature of the B-type sleeve welding of the in-service natural gas pipeline to be determined by back-calculating the temperature relationship through the preheating temperature range of the pipe body reinforcement welding is as follows:

[0085] Finally, considering the preheating temperature not exceeding 400℃, the difficulty and cost of preheating in field construction, and the preheating temperature range calculated based on the above theories, the final preheating temperature for welding the sleeve end is determined based on the principle of taking the lowest preheating temperature within the preheating temperature range. Determining the final preheating temperature for welding the sleeve end requires comprehensive consideration of the impact of pipeline preheating temperature on the strength and toughness of the pipe material, as well as the difficulty and cost of field construction. When preheating in-service natural gas pipelines, it is necessary to consider both preventing post-weld cold cracking and the potential impact of excessively high preheating temperatures on the mechanical properties of the pipe material.

[0086] In summary, when this solution is used to preheat the temperature field of in-service oil pipelines or other fluid media pipelines, it is necessary to find and calculate the relevant parameters of the fluid medium based on the operating conditions of the fluid medium in the pipeline, and the parameters listed in the embodiments of this invention cannot be applied directly.

[0087] Example 1, for In-service reinforcement of a 1219×18.4 mm X80 natural gas pipeline using a type B sleeve. The natural gas composition inside the pipeline is 97.0% methane, 1.5% ethane, 0.5% propane, and 1.0% nitrogen. The natural gas temperature is 50℃, the flow rate is 10 m / s, the manual arc welding voltage is 20–26 V, the welding current is 90–120 A, the welding speed is 10–16 cm / min, and the preheating width of the pipe body is 300 mm. The determination of the preheating temperature for welding the end of the type B sleeve includes the following steps:

[0088] The first step was to analyze the relationship between the preheating temperature and cold crack susceptibility of the X80 natural gas pipeline. JMatPro software was used to plot the continuous cooling transition diagram of the X80 pipeline during welding (e.g., ...). Figure 3 As shown, based on the times corresponding to the formation of ferrite and pearlite in the continuous cooling transformation diagram of the weld, the upper and lower limits of the t8 / 5 time during weld cooling are determined. From the diagram, the critical t value for X80 pipe cooling from high temperature to room temperature without the formation of hardened structures is analyzed. 8 / 5 Time. When the actual cooling time t 8 / 5 > At that time, no cracks occur near the fusion line in the weld heat-affected zone; when t 8 / 5 < At this rate, cracks may occur because when the cooling rate is slower than the f-curve, some proeutectoid ferrite transformation will occur, which usually does not crack spontaneously and has good plasticity and toughness. However, if t 8 / 5 Exceed If the cooling rate is too slow, the toughness will decrease. The optimal welding conditions should ensure that the cooling profile falls between the f and p curves, i.e., t... 8 / 5 The lower limit is The upper limit is .Depend on Figure 1 It can be seen that, The value is 3.04s. The value is 341.4s. According to Formula 3, the linear energy during welding is calculated to be 9.0 KJ / cm.

[0089] (Formula 3)

[0090] In the formula, The thermal efficiency of manual arc welding is taken as 0.75.

[0091] The welding voltage for manual arc welding;

[0092] Welding current for manual arc welding;

[0093] : Welding speed of manual arc welding.

[0094] Furthermore, based on t 8 / 5 The relationship between time and preheating temperature (Formula 1) determines that the preheating temperature range for pipe welding of natural gas pipelines under conditions without transporting fluid is 110℃~492℃.

[0095] The second step is to calculate the thermal conductivity of the flowing natural gas. Based on the composition and content of the natural gas in the pipe (97.0% methane, 1.5% ethane, 0.5% propane and 1.0% nitrogen), relevant data were consulted to obtain the thermal conductivity (W / (m•K)) of the four gases at normal pressure, as shown in Table 1. The thermal conductivity at different temperature points can be obtained through linear fitting.

[0096] Table 1 Thermal conductivity of gases at normal pressure (W / (m•K))

[0097]

[0098] Then, the thermal conductivity of natural gas was calculated using the formula for calculating the thermal conductivity of mixed gases (Formula 4), and the thermal conductivity of natural gas at 50℃ was found to be 0.037.

[0099] (Formula 4)

[0100] In the formula, y i : The mole fraction of component i in the gas mixture;

[0101] M i The relative molecular mass of component i in the gas mixture;

[0102] λi : Thermal conductivity of component i in the gas mixture.

[0103] The third step is to calculate the viscosity of the flowing natural gas. The viscosities of the four gases at normal pressure are shown in Table 2, obtained from relevant literature.

[0104] Table 2 Viscosity of gases at normal pressure

[0105]

[0106] Then, the viscosity of natural gas was calculated using the formula for calculating the viscosity of mixed gases (Formula 5), ​​and the viscosity of natural gas at 50℃ was found to be 0.0000119 pa·s.

[0107] (Formula 5)

[0108] In the formula, Viscosity of natural gas under low pressure;

[0109] : The viscosity of component i under the same pressure;

[0110] : The mole fraction of component i in natural gas;

[0111] : Molecular weight of component i.

[0112] The fourth step is to calculate the Prandtl number of the flowing natural gas. The isobaric specific heat capacities of the four gases at atmospheric pressure are obtained from relevant data, as shown in Table 3. The isobaric specific heat capacity of the mixed gas can be calculated using Formula 6, yielding the isobaric specific heat capacity of natural gas at 50℃ as 2771.4 J / kg·K.

[0113] Table 3. Specific heat capacity at constant pressure of each component of natural gas at a given temperature (J / kg·K)

[0114]

[0115] The isobaric specific heat capacity of a gas mixture can be calculated using the following formula:

[0116] (Formula 6)

[0117] In the formula, : Specific heat capacity at constant pressure of a gas mixture, J / (kg·K);

[0118] : Specific heat capacity at constant pressure of component i, J / (kg·K).

[0119] Then, the thermal conductivity, viscosity and specific heat capacity of natural gas obtained from the above steps are substituted into Formula 7 to calculate the Prandtl number of natural gas, and the Prandtl number of natural gas at 50℃ is 0.602.

[0120] (Formula 7)

[0121] In the formula, The viscosity of natural gas;

[0122] Specific heat capacity of natural gas at constant pressure;

[0123] λ: Thermal conductivity of the gas mixture.

[0124] Step 5: Calculation of the density of flowing natural gas. Based on relevant data, the densities of the constituent gases of natural gas at different temperatures are shown in Table 4. Using the formula for calculating the density of mixed gases (Formula 8), the density of the mixed gas natural gas is calculated, yielding a density of 58.219 kg / m³ at 50℃.

[0125] = (Formula 8)

[0126] In the formula, ;

[0127] .

[0128] Table 4. Densities of natural gas components at a given temperature (kg / m3)

[0129]

[0130] Step 6: Calculation of the Reynolds number of flowing natural gas. Substitute the natural gas flow velocity v, pipe diameter d, density ρ, and natural gas viscosity μ into the Reynolds number calculation formula (Formula 9) to calculate the Reynolds number of natural gas, obtaining a Reynolds number of 68292121.84 for natural gas at 50℃.

[0131] (Formula 9)

[0132] Step 7: Calculation of the Nusselt number of flowing natural gas. Substitute the Reynolds number Re and Prandtl number Pr of natural gas into the Nusselt number calculation formula (Formula 10) to calculate the Nusselt number of natural gas, and obtain the Nusselt number of natural gas at 50℃ as 34758.263.

[0133] (Formula 10)

[0134] In the formula, ;

[0135] .

[0136] Step 8: Calculation of the heat transfer coefficient of flowing natural gas. This involves calculating the Nusselt number of the natural gas. Substituting the thermal conductivity λ into the heat exchange coefficient calculation formula (Formula 11), the heat exchange coefficient of natural gas at 50℃ is calculated to be 1364.222.

[0137] = (Formula 11)

[0138] In the formula, ;

[0139] ;

[0140] D .

[0141] Step 9: Calculation of the boundary of the heat-affected zone (HAZ) at the end of the reinforcing sleeve. According to relevant theories of welding metallurgy, the temperature range of the HAZ during welding is between 727℃ and Ac3. Taking 727℃ as the boundary temperature of the HAZ, the width of the HAZ during reinforcing welding is calculated to be 5.0 mm using Formula 2.

[0142] Step 10: Establishment of the finite element model for preheating the in-service natural gas pipeline and temperature field analysis. Based on the preheating temperature of the pipe body under no-fluid transport conditions calculated in Step 1, preliminary loading is performed. The thermal radiation coefficient and convective heat transfer coefficient of the pipeline outer wall are adopted as 0.6 and 0.000005 respectively (for the pipeline in air environment). The heat exchange coefficient of the pipeline inner wall is adopted as 1364.222 W / (m²•K) calculated in Step 8. The preheating width of the pipe body is set to 300 mm in the calculation model, and the preheating temperatures are set to 300℃ and 390℃ respectively. Finally, the temperature of the pipeline outer surface and the boundary temperature of the heat-affected zone (HAZ) 5.0 mm from the outer surface are obtained. The temperature difference between the HAZ boundary and the pipeline outer surface is calculated. In Origin, the temperature difference is used as the ordinate and the outer surface temperature as the abscissa, and a fitting is performed to obtain the relationship between the temperature difference between the bottom of the HAZ and the pipeline outer surface and the pipeline outer surface temperature under different natural gas flow conditions. Figure 4 As shown in the figure (in the finite element calculation model, the preheating temperature of the outer surface of the pipe is set to 300℃ and 390℃ respectively, and the difference between the outer surface temperature and the bottom temperature of the weld heat-affected zone at the two temperatures is obtained. The two sets of data are then fitted to plot the data line shown in the figure.), the fitted relationship is y=a+b×x, that is,

[0143] ΔT = a + b × T (Formula 12)

[0144] In the formula, ΔT is the temperature difference between the bottom of HAZ and the outer surface of the pipe;

[0145] T is the preheating temperature of the outer surface of the pipe;

[0146] a and b are unknown values.

[0147] in addition,

[0148] T = ΔT + T h (Formula 13)

[0149] In the formula, T h The temperature at the HAZ boundary.

[0150] Substituting the minimum preheating temperature Th = 110℃ at 5.0 mm into formulas 12 and 13, we can calculate... The minimum preheating temperature of the outer surface of the 1219×18.4mm pipe is 130℃; substituting the maximum preheating temperature Th = 492℃ at 5.0mm into formulas 12 and 13, we can calculate... The maximum preheating temperature for the outer surface of the 1219×18.4mm pipe is 562℃. Since the strength and toughness of X80 pipeline steel decrease significantly after being heated to above 400℃ and then cooled to room temperature, and considering that the preheating temperature should not affect the mechanical properties of the pipe material, a heating temperature below 400℃ is more suitable. Taking into account both avoiding post-weld cold cracking and preventing insufficient toughness near the weld, a preheating temperature between 130℃ and 400℃ is more appropriate. Furthermore, in field construction, higher preheating temperatures require greater power from the preheating equipment, increasing the difficulty and cost of on-site construction. Therefore, the preheating temperature for welding the end of the B-type sleeve of this X80 pipe is set at 140℃. Welding is performed according to this preheating temperature and appropriate welding procedures. The macroscopic morphology of the welded joint is as follows. Figure 5 As shown ( The weld morphology of the 1219×18.4mm pipe type B sleeve repaired circumferential fillet weld at 0℃, 90℃, 180℃ and 270℃ was obtained. No macroscopic welding defects were found in the joint.

[0151] Example 2, for In-service reinforcement of a 1016×14.6 mm X80 natural gas pipeline using a type B sleeve. The natural gas composition inside the pipeline is 97.0% methane, 1.5% ethane, 0.5% propane, and 1.0% nitrogen. The natural gas temperature is 100℃, the flow rate is 10 m / s, the manual arc welding voltage is 20–26 V, the welding current is 90–120 A, the welding speed is 10–16 cm / min, and the preheating width of the pipe body is 300 mm. The determination of the preheating temperature for welding the end of the type B sleeve includes the following steps:

[0152] The first step was to analyze the relationship between the preheating temperature and cold crack susceptibility of the X80 natural gas pipeline. JMatPro software was used to plot the continuous cooling transition diagram of the X80 pipeline during welding (e.g., ...). Figure 3 As shown in the figure, The value is 3.04s. The value is 341.4s. According to Formula 3, the heat input during welding is calculated to be 8.5 KJ / cm, and then based on t... 8 / 5 The relationship between time and preheating temperature (Formula 1) determines that the preheating temperature range for pipe welding of natural gas pipelines under conditions without transporting fluid is 120℃~492℃.

[0153] The second step is to calculate the thermal conductivity of the flowing natural gas. Based on the composition and content of the natural gas in the pipeline, relevant data were consulted to obtain the thermal conductivity (W / (m•K)) of the four gases at normal pressure, as shown in Table 1. Linear fitting was used to obtain the thermal conductivity at different temperature points. Then, the thermal conductivity of the natural gas was calculated using the formula for calculating the thermal conductivity of mixed gases (Formula 4), yielding a thermal conductivity of 0.044 for natural gas at 100℃.

[0154] The third step is to calculate the viscosity of the flowing natural gas. Relevant data were consulted to obtain the viscosities of the four gases at normal pressure, as shown in Table 2. Then, the viscosity of the natural gas was calculated using the formula for calculating the viscosity of a mixed gas (Formula 5), ​​yielding a viscosity of 0.0000135 Pa·s at 100℃.

[0155] The fourth step is to calculate the Prandtl number of the flowing natural gas. The isobaric specific heat capacities of the four gases at atmospheric pressure are obtained from relevant data, as shown in Table 3. The isobaric specific heat capacity of the mixed gas can be calculated using Formula 6, yielding the isobaric specific heat capacity of natural gas at 100℃ as 2719.2 J / kg·K.

[0156] Then, the thermal conductivity, viscosity and specific heat capacity of natural gas obtained from the above steps are substituted into Formula 7 to calculate the Prandtl number of natural gas, and the Prandtl number of natural gas at 100℃ is 0.603.

[0157] Step 5: Calculation of the density of flowing natural gas. Relevant data were consulted to obtain the densities of the constituent gases of natural gas at different temperatures, as shown in Table 4. The density of natural gas was calculated using the formula for calculating the density of mixed gases (Formula 8), yielding a density of 46.246 kg / m³ at 100℃.

[0158] Step 6: Calculation of the Reynolds number of flowing natural gas. Substitute the natural gas flow velocity v, pipe diameter d, density ρ, and natural gas viscosity μ into the Reynolds number calculation formula (Formula 9) to calculate the Reynolds number of natural gas, obtaining a Reynolds number of 47,746,405.62 for natural gas at 100℃.

[0159] Step 7: Calculation of the Nusselt number of flowing natural gas. Substitute the Reynolds number Re and Prandtl number Pr of natural gas into the Nusselt number calculation formula (Formula 10) to calculate the Nusselt number of natural gas, and obtain the Nusselt number of natural gas at 100℃ as 26129.284.

[0160] Step 8: Calculation of the heat transfer coefficient of flowing natural gas. This involves calculating the Nusselt number of the natural gas. Substituting the thermal conductivity λ into the heat exchange coefficient calculation formula (Formula 11), the heat exchange coefficient of natural gas at 50℃ is calculated to be 1140.476.

[0161] Step 9: Calculation of the boundary of the heat-affected zone (HAZ) at the end of the reinforcing sleeve. According to relevant theories of welding metallurgy, the temperature range of the HAZ during welding is between 727℃ and Ac3. Taking 727℃ as the boundary temperature of the HAZ, the width of the HAZ during reinforcing welding is calculated to be 4.8mm using Formula 2.

[0162] Step 10: Establishment of the finite element model for preheating the in-service natural gas pipeline and temperature field analysis. A finite element analysis model is established based on the specifications of the in-service natural gas pipeline. Preliminary loading is performed based on the pipe welding preheating temperature under no-fluid conditions calculated in Step 1. The thermal radiation coefficient and convective heat transfer coefficient of the pipeline outer wall are set to 0.6 and 0.000005 respectively (for air conditions). The heat exchange coefficient of the pipeline inner wall is set to 1140.476 W / (m²•K) calculated in Step 8. The preheating width of the pipe is set to 300 mm, and the preheating temperatures are set to 300℃ and 390℃ respectively. The final temperature of the pipeline outer surface and the edge temperature of the heat-affected zone (HAZ) 4.8 mm from the outer surface are obtained. The temperature difference between the HAZ edge and the pipeline outer surface is calculated. In Origin, the temperature difference is used as the ordinate and the outer surface temperature as the abscissa, and a fitting is performed. Formulas 12 and 13 are used to obtain the relationship between the temperature difference between the bottom of the HAZ and the pipeline outer surface and the pipeline outer surface temperature under different natural gas flow conditions. Substituting the minimum preheating temperature Th = 120℃ at 4.8mm into equations 12 and 13, we can calculate... The minimum preheating temperature of the outer surface of the 1016×14.6mm pipe is 125℃; substituting the maximum preheating temperature Th = 492℃ at the 4.8mm mark into formulas 12 and 13, we can calculate... The maximum preheating temperature for the outer surface of the 1016×14.6mm pipe is 562℃. Considering both preventing post-weld cold cracking and ensuring sufficient toughness near the weld, a preheating temperature between 125℃ and 400℃ is deemed suitable. Furthermore, taking into account the difficulty and cost of on-site construction, the preheating temperature for welding the end of the type B sleeve of the X80 pipe was set at 130℃. Welding was performed according to this preheating temperature and appropriate welding procedures. The macroscopic morphology of the welded joint is as follows: Figure 6 As shown (the weld morphology of the 1016×14.6mm pipe type B sleeve repaired circumferential fillet weld at 0℃, 90℃, 180℃ and 270℃), no macroscopic welding defects were observed in the joint.

[0163] Preferably, in any of the above embodiments, the basic parameters of the historical flowing natural gas pipeline include:

[0164] The thermal conductivity, viscosity, Prandtl number, density, Reynolds number, Nusselt number, heat transfer coefficient, and boundary of the heat-affected zone at the end of the reinforcing sleeve weld of natural gas.

[0165] Preferably, in any of the above embodiments, the process of determining the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline type B sleeve under conditions without fluid transport, based on the upper time limit and the lower time limit, is as follows:

[0166] Input the upper time limit and the lower time limit into the first formula to determine the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline in-service type B sleeve under conditions without fluid transport.

[0167] The first formula is:

[0168] ;

[0169] in, For manual arc welding heat input; T0 represents the thermal conductivity of the natural gas pipeline; T0 represents the preheating temperature range for pipe body reinforcement welding under conditions of no fluid transport; t0 represents the temperature range of the natural gas pipeline under conditions of no fluid transport. 8 / 5 The time limit is defined as either the upper or lower limit. The heat input for manual arc welding refers to the welding voltage multiplied by the welding current multiplied by the welding efficiency, and then divided by the welding speed.

[0170] like Figure 2 As shown, a system for determining the preheating temperature for welding type B sleeves includes:

[0171] The determination module 100 is used to: process the relationship between the preheating temperature and cold crack sensitivity of the preset natural gas pipeline through drawing software, obtain the upper limit and lower limit of the time during which the material of the in-service B-type sleeve of the preset natural gas pipeline does not produce hardened structure when cooled from high temperature to room temperature, and determine the preheating temperature range of the pipe body reinforcement welding of the in-service B-type sleeve of the preset natural gas pipeline under the condition of no transport fluid based on the upper limit and the lower limit.

[0172] The construction module 200 is used to: obtain the basic parameters of historical flowing natural gas pipelines, and construct a finite element analysis model based on the basic parameters and the specifications of the pre-set in-service B-type sleeve of the natural gas pipeline to obtain the model to be used;

[0173] The input module 300 is used to: input a preset temperature into the model to be used, and obtain the temperature value at each preset position of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined, wherein the preset temperature is determined according to the tolerance of the material of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined.

[0174] The temperature relationship module 400 is used to: establish a temperature relationship between the temperature value at each preset location and the preset temperature at the boundary of the weld heat-affected zone of the in-service B-type sleeve of the natural gas pipeline to be preheated at the preheating temperature to be determined, based on the temperature value;

[0175] The result module 500 is used to: back-calculate the temperature relationship by the preheating temperature range of the pipe body reinforcement welding to obtain the in-service B-type sleeve welding preheating temperature of the natural gas pipeline.

[0176] In some possible implementations, this invention provides a theoretical basis for determining the preheating temperature for in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature for in-service pipeline reinforcement welding, which leads to performance degradation in the heat-affected zone of the joint. The method for calculating the preheating temperature for welding type B sleeves for in-service natural gas pipeline reinforcement proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. This method is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines.

[0177] Preferably, in any of the above embodiments, the basic parameters of the historical flowing natural gas pipeline include:

[0178] The thermal conductivity, viscosity, Prandtl number, density, Reynolds number, Nusselt number, heat transfer coefficient, and boundary of the heat-affected zone at the end of the reinforcing sleeve weld of natural gas.

[0179] Preferably, in any of the above embodiments, the process of determining the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline type B sleeve under conditions without fluid transport, based on the upper time limit and the lower time limit, is as follows:

[0180] Input the upper time limit and the lower time limit into the first formula to determine the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline in-service type B sleeve under conditions without fluid transport.

[0181] The first formula is:

[0182] ;

[0183] in, For manual arc welding heat input; T0 represents the thermal conductivity of the natural gas pipeline; T0 represents the preheating temperature range for pipe body reinforcement welding under conditions of no fluid transport; t0 represents the temperature range of the natural gas pipeline under conditions of no fluid transport. 8 / 5 The time limit is defined as either the upper or lower limit. The heat input for manual arc welding refers to the welding voltage multiplied by the welding current multiplied by the welding efficiency, and then divided by the welding speed.

[0184] Another technical solution of the present invention to solve the above-mentioned technical problems is as follows: a storage medium storing instructions, wherein when a computer reads the instructions, the computer executes the method described in any of the above-mentioned methods.

[0185] In some possible implementations, this invention provides a theoretical basis for determining the preheating temperature for in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature for in-service pipeline reinforcement welding, which leads to performance degradation in the heat-affected zone of the joint. The method for calculating the preheating temperature for welding type B sleeves for in-service natural gas pipeline reinforcement proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. This method is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines.

[0186] Another technical solution of the present invention to solve the above-mentioned technical problems is as follows: an electronic device, including the above-mentioned storage medium and a processor that executes the instructions in the above-mentioned storage medium.

[0187] In some possible implementations, this invention provides a theoretical basis for determining the preheating temperature for in-service pipeline reinforcement welding, solving the problem of difficulty in accurately determining the preheating temperature for in-service pipeline reinforcement welding, which leads to performance degradation in the heat-affected zone of the joint. The method for calculating the preheating temperature for welding type B sleeves for in-service natural gas pipeline reinforcement proposed in this invention can be applied to natural gas pipelines of different specifications, transport media, transport speeds, and transport temperatures. This method is not only applicable to the reinforcement of in-service natural gas pipelines, but also to the reinforcement of in-service oil pipelines and decommissioned natural gas and oil pipelines.

[0188] Readers should understand that in the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0189] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the method embodiments described above are merely illustrative. For instance, the division of steps is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple steps may be combined or integrated into another step, or some features may be ignored or not executed.

[0190] If the above methods are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0191] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for determining the preheating temperature for welding type B sleeves, characterized in that, include: By processing the relationship between the preheating temperature and cold crack sensitivity of the preset natural gas pipeline using drawing software, the upper and lower limits of the time during which the material of the in-service B-type sleeve of the preset natural gas pipeline does not produce hardened structure during the cooling process from high temperature to room temperature are obtained. Based on the upper and lower limits of the time, the range of preheating temperature for pipe body reinforcement welding of the in-service B-type sleeve of the preset natural gas pipeline under the condition of no transport fluid is determined. Obtain the basic parameters of historical flowing natural gas pipelines, and construct a finite element analysis model based on the basic parameters and the specifications of the pre-set in-service B-type sleeve of the natural gas pipeline to obtain the model to be used; Input a preset temperature into the model to be used to obtain the temperature value at each preset position of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined. The preset temperature is determined based on the material tolerance of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined. Based on the temperature values, establish the temperature relationship between the temperature values ​​and the preset temperature at each preset location of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline to be preheated at the preheating temperature to be determined. The in-service B-type sleeve welding preheating temperature of the natural gas pipeline is obtained by inversely calculating the temperature relationship using the preheating temperature range of the pipe body reinforcement welding.

2. The method for determining the preheating temperature for welding type B sleeves according to claim 1, characterized in that, The basic parameters of the historical flowing natural gas pipeline include: The thermal conductivity, viscosity, Prandtl number, density, Reynolds number, Nusselt number, heat transfer coefficient, and boundary of the heat-affected zone at the end of the reinforcing sleeve weld of natural gas.

3. The method for determining the preheating temperature for welding type B sleeves according to claim 2, characterized in that, The process of determining the preheating temperature range for pipe body reinforcement welding of the pre-set type B sleeve of the in-service natural gas pipeline under conditions without fluid transport, based on the upper time limit and the lower time limit, is as follows: Input the upper time limit and the lower time limit into the first formula to determine the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline in-service type B sleeve under conditions without fluid transport. The first formula is: Among them, Q v λ represents the heat input for manual arc welding; λ represents the thermal conductivity of the natural gas pipeline; T0 represents the preheating temperature range for pipe reinforcement welding of the natural gas pipeline under conditions without transporting fluid; t 8 / 5 The time limit is defined as either the upper or lower limit. The heat input for manual arc welding refers to the welding voltage multiplied by the welding current multiplied by the welding efficiency, and then divided by the welding speed.

4. A system for determining the preheating temperature for welding type B sleeves, characterized in that, include: The determination module is used to: process the relationship between the preheating temperature and cold crack sensitivity of the preset natural gas pipeline through drawing software, obtain the upper and lower limits of the time during which the material of the in-service B-type sleeve of the preset natural gas pipeline does not produce hardened structure when cooled from high temperature to room temperature, and determine the preheating temperature range of the pipe body reinforcement welding of the in-service B-type sleeve of the preset natural gas pipeline under the condition of no transport fluid based on the upper and lower limits of the time. The construction module is used to: obtain the basic parameters of historical flowing natural gas pipelines, and construct a finite element analysis model based on the basic parameters and the specifications of the pre-set in-service B-type sleeve of the natural gas pipeline to obtain the model to be used; The input module is used to: input a preset temperature into the model to be used, and obtain the temperature value at each preset position of the weld heat-affected zone boundary of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined. The preset temperature is determined based on the material tolerance of the in-service B-type sleeve of the natural gas pipeline whose preheating temperature is to be determined. The temperature relationship module is used to: establish a temperature relationship between the temperature value at each preset location and the preset temperature at the boundary of the weld heat-affected zone of the in-service B-type sleeve of the natural gas pipeline to be preheated at the preheating temperature to be determined, based on the temperature value; The results module is used to: inversely deduce the preheating temperature of the in-service B-type sleeve of the natural gas pipeline by using the preheating temperature range of the pipe body reinforcement welding to obtain the preheating temperature of the temperature relationship.

5. The preheating temperature determination system for welding type B sleeves according to claim 4, characterized in that, The basic parameters of the historical flowing natural gas pipeline include: The thermal conductivity, viscosity, Prandtl number, density, Reynolds number, Nusselt number, heat transfer coefficient, and boundary of the heat-affected zone at the end of the reinforcing sleeve weld of natural gas.

6. The preheating temperature determination system for B-type sleeve welding according to claim 4, characterized in that, The process of determining the preheating temperature range for pipe body reinforcement welding of the pre-set type B sleeve of the in-service natural gas pipeline under conditions without fluid transport, based on the upper time limit and the lower time limit, is as follows: Input the upper time limit and the lower time limit into the first formula to determine the preheating temperature range for pipe body reinforcement welding of the pre-set natural gas pipeline in-service type B sleeve under conditions without fluid transport. The first formula is: Among them, Q v λ represents the heat input for manual arc welding; λ represents the thermal conductivity of the natural gas pipeline; T0 represents the preheating temperature range for pipe reinforcement welding of the natural gas pipeline under conditions without fluid transport; t 8 / 5 The time limit is defined as either the upper or lower limit. The heat input for manual arc welding refers to the welding voltage multiplied by the welding current multiplied by the welding efficiency, and then divided by the welding speed.

7. A storage medium, characterized in that, The medium stores instructions that, when read by a computer, cause the computer to execute the method as described in any one of claims 1 to 3.

8. An electronic device, characterized in that, Includes the storage medium of claim 7 and a processor that executes instructions within the storage medium.

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