A welding process for pipelines in closed air shafts

Abstract

The present invention discloses a pipeline welding process in a closed air shaft, and relates to the technical field of gas shielded welding. The method comprises the following steps: collecting interference gas data and gas flow data inside the closed air shaft, and calculating the inert gas reference gas flow rate; setting a protective gas flow fluctuation interval, monitoring the interference gas concentration in the closed air shaft during welding, adjusting the flow rate of gas shielded welding related protective gas based on the concentration of the interference gas, and calculating the interference gas concentration growth rate; when the protective gas flow rate reaches the peak value of the gas flow fluctuation interval, suspending the gas shielded welding operation, and concentrating on the closed air shaft exhaust operation. The present invention is aimed at pipeline welding in a closed air shaft, and can adjust the protective gas flow rate in real time to reduce the accumulation of interference gas, thereby reducing the occurrence of welding defects such as pores and slag inclusions, and comprehensively setting the exhaust rate of the inner wall of the air shaft to prevent the problem of unstable gas flow leading to reduced welding quality.

Description

Technical Field

[0001] The invention relates to the technical field of gas shielded welding, and in particular to a pipeline welding process in a closed air shaft. Background Art

[0002] Gas shielded welding is a method of welding using gas shielded arc. During the welding process, the heat of the arc is used to melt the electrode and the workpiece to form a weld. Inert gases, such as argon, are often used as shielding gases for welding operations. During the welding process, attention must be paid to the concentration of interfering gases in the welding environment to avoid interference with the shielding gas.

[0003] When welding pipes in a closed air shaft, due to the special environment of the closed air shaft, if the gas in the closed air shaft is continuously pumped out, the gas pressure will decrease, resulting in unstable gas flow, especially near the welding area, affecting the welding process. In addition, large amounts of gas extraction will easily cause uneven distribution of gas inside the air shaft, affecting the uniform coverage of the shielding gas, resulting in poor shielding gas effect, causing pores, cracks or other defects in the weld.

[0004] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention

[0005] In view of the problems in the related technology, the present invention proposes a pipeline welding process in a closed air shaft to overcome the above-mentioned technical problems existing in the existing related technology.

[0006] To this end, the specific technical solution adopted by the present invention is as follows:

[0007] A pipeline welding process in a closed air shaft, the method comprising the following steps:

[0008] S1. Collect the interfering gas data and gas flow data inside the closed air shaft, and calculate the reference gas flow rate of the protective gas;

[0009] S2. Set the fluctuation range of the shielding gas flow rate, monitor the concentration of interfering gas in the closed air shaft during welding, adjust the flow rate of shielding gas related to gas shielded welding based on the concentration of interfering gas, and calculate the growth rate of the interfering gas concentration;

[0010] S3. When the protective gas flow reaches the peak value of the gas flow fluctuation range, the gas shielded welding operation is suspended, and the closed air shaft exhaust operation is concentrated at the same time, until the interference gas concentration drops to the welding threshold, and the welding operation is repeated;

[0011] S4. Combine the growth rate of the interfering gas concentration, the gas generation rate of the operator, and other gas sources to comprehensively calculate the growth rate of the total interfering gas concentration and set the exhaust rate of the exhaust equipment.

[0012] As a preferred embodiment, the S1 includes the following sub-steps:

[0013] S11. Before welding the pipeline, use gas sensors and gas analyzers to collect data on the types of interfering gases in the closed air shaft. Interfering gases include oxygen, carbon dioxide, and nitrogen.

[0014] S12. An anemometer is set at the welding position of the pipeline inside the closed air shaft to obtain the gas flow velocity V at the welding position. g ;

[0015] S13. Calculate the inert gas reference gas flow rate according to the gas flow rate at the welding position. The specific algorithm formula is:

[0016] Q B =Q i +α·V g ;

[0017] Among them, Q B represents the reference gas flow rate, Q i Represents the ideal gas flow, that is, the gas flow usually set under standard conditions without wind or environmental interference, V g represents the measured gas flow velocity at the welding position, and α represents the adjustment coefficient of wind speed to gas flow.

[0018] As a preferred embodiment, S2 includes the following sub-steps:

[0019] S21. Based on the reference gas flow rate and in combination with the economic benefits of the inert protective gas, the maximum protective gas flow rate is set, and the protective gas flow rate fluctuation range is calculated;

[0020] S22. Obtain the total value of excessive concentration of interfering gases at the pipeline welding position through a gas analyzer, including oxygen concentration, carbon dioxide concentration, nitrogen concentration, nitrogen oxide concentration, ozone concentration, and carbon monoxide concentration, of which:

[0021] L 过 =L 总 -L 标 ;

[0022] Among them, L 过 is the total value of excess concentration of interfering gas, L 总 Represents the total value of the interfering gas concentration, L 标 Represents the standard interfering gas concentration value;

[0023] S23. According to the total value of the excessive concentration of the interfering gas, the flow rate of the shielding gas in the gas shielded welding process is synchronously adjusted.

[0024] As a preferred implementation, the S21 includes the following sub-steps:

[0025] S211, obtain reference gas flow Q B , according to the type of inert gas used and the price of the relevant inert gas, set the maximum value of the protective gas flow rate and calculate the protective gas flow fluctuation range. The algorithm formula is:

[0026] Q max =Q B (1+β);

[0027] Among them, Q max represents the maximum protective gas flow rate, β represents the maximum flow rate factor, Q B represents the reference gas flow rate. The protective gas flow fluctuation range is set based on the maximum protective gas flow rate. The protective gas flow fluctuation range is [Q B ,Q max ].

[0028] As a preferred embodiment, the S23 includes the following sub-steps:

[0029] S231. Collect the corresponding data of the historical flow rate of protective gas and the total value of the excessive concentration of interfering gas, and construct a regression model, the algorithm formula of which is:

[0030]

[0031] Among them, Y represents the protective gas adjustment flow rate, Q B represents the reference gas flow rate, λ represents the influence coefficient, L 过 It is the total value of excess concentration of interfering gas;

[0032] S232, set the time interval T, obtain the welding interference gas concentration value at the start position of the time interval and the welding interference gas concentration value at the end position of the time interval through the gas analyzer, and calculate the welding interference gas growth rate. The algorithm formula is:

[0033]

[0034] Among them, V 焊接 Represents the growth rate of welding interference gas, C 终点 Represents the welding interference gas concentration value at the end of the time interval, C 起点 Represents the welding interference gas concentration value at the starting position of the time interval.

[0035] As a preferred implementation, S3 includes the following sub-steps:

[0036] S31. Compare the protective gas adjustment flow rate with the peak value of the gas flow fluctuation range, and adjust the gas shielded welding operation. The specific steps are as follows:

[0037] When Y≤Q max When , adjust the shielding gas flow rate to be consistent with the value of Y, and continue the gas shielded welding operation;

[0038] When Y>Q max When the gas shielded welding operation is stopped;

[0039] S32. After stopping the gas shielded welding operation, exhaust the inside of the closed air shaft through a portable exhaust device, and record the total value of the interfering gas concentration L through a gas analyzer. 总 ;

[0040] S33, set the welding threshold θ, based on the total value L of the interference gas concentration 总 , combined with the welding threshold θ for comparison, the specific steps are:

[0041] When L 总 ≤θ, continue the pipeline welding operation;

[0042] When L 总 >θ, continue to exhaust the air using the portable exhaust equipment.

[0043] As a preferred embodiment, the S4 includes the following sub-steps:

[0044] S41. When welding is stopped, let the operator place himself in a closed air shaft, collect the total gas concentration value C1 at time t1 and the total gas concentration value C2 at time t2 in the closed air shaft through a gas analyzer, and calculate the gas growth rate V of other gas sources. 其他 , and its algorithm formula is:

[0045]

[0046] S42, combined with other gas sources gas growth rate V 其他 The growth rate of welding interference gas V 焊接 , calculate the total interfering gas concentration growth rate V 总 , and its algorithm formula is:

[0047] V 总 =V 焊接 +V 其他 .

[0048] As a preferred implementation, the S42 further includes the following sub-steps:

[0049] S421, combined with the total interfering gas concentration growth rate V 总Fluctuation range of protective gas flow

[0050] [Q B ,Q max ], set the continuous exhaust rate of the portable exhaust device, the specific steps are:

[0051] P=V 总 η;

[0052] Where P is the exhaust efficiency of the portable exhaust equipment, V 总 represents the growth rate of the total interfering gas concentration, and η represents the compensation interval.

[0053] The beneficial effects of the present invention are:

[0054] 1. The present invention collects data inside the closed air shaft during the gas shielded welding process for pipeline welding inside the closed air shaft, and adjusts the shielding gas flow rate in the gas shielded welding process in real time in combination with the growth rate of the interfering gas to meet the needs of welding. Real-time adjustment of the shielding gas flow rate can reduce the accumulation of interfering gas and reduce the occurrence of welding defects such as pores and slag inclusions.

[0055] 2. The present invention sets the fluctuation range of the protective gas flow rate by combining the economic benefits of the specific protective gas and the economic benefits of the relevant welding project, limits the maximum value of the protective gas flow rate caused by the accumulation of interfering gas in the closed air shaft, avoids economic losses caused by excessive use of gas, and improves the overall economic benefits of the project;

[0056] 3. The present invention comprehensively calculates the growth rate of the interfering gas concentration inside the closed air shaft and the growth rate of other gas sources, comprehensively considers the fluctuation range of the protective gas flow rate, sets the appropriate exhaust rate of the exhaust equipment, ensures that the protective gas adjustment amount is within the range that meets the economic benefits and welding quality, and avoids the problem that the excessive exhaust rate inside the closed air shaft causes the gas pressure to decrease, resulting in unstable gas flow and reduced welding quality;

[0057] 4. The present invention sets a compensation interval to compensate for the exhaust efficiency of the exhaust equipment based on the growth rate of the interfering gas concentration and the growth rate of other gas sources, thereby preventing a large amount of air extraction from causing uneven distribution of gas inside the wind shaft, affecting the uniform coverage of the protective gas at the welding site, and further improving the quality of the weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0059] Figure 1 The present invention is a flow chart of a pipeline welding process in a closed air shaft according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] To further illustrate each embodiment, the present invention provides drawings, which are part of the disclosure of the present invention and are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in the field should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0061] According to an embodiment of the present invention, a pipeline welding process in a closed air shaft is provided.

[0062] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. Figure 1 As shown, according to a closed air shaft pipeline welding process of an embodiment of the present invention, the method comprises the following steps:

[0063] S1. Collect the interfering gas data and gas flow data inside the closed air shaft, and calculate the reference gas flow rate of the protective gas;

[0064] S11. Before welding the pipeline, use gas sensors and gas analyzers to collect data on the types of interfering gases in the closed air shaft. Interfering gases include oxygen, carbon dioxide, and nitrogen.

[0065] S12. An anemometer is set at the welding position of the pipeline inside the closed air shaft to obtain the gas flow velocity V at the welding position. g ;

[0066] S13. Calculate the inert gas reference gas flow rate according to the gas flow rate at the welding position. The specific algorithm formula is:

[0067] Q B =Q i +α·V g ;

[0068] Among them, Q B represents the reference gas flow rate, Q i Represents the ideal gas flow, that is, the gas flow usually set under standard conditions without wind or environmental interference, V g represents the measured gas flow velocity at the welding position, and α represents the adjustment coefficient of wind speed to gas flow.

[0069] It should be noted that the benchmark gas flow value is a flow rate set to ensure that the shielding gas during welding can effectively cover the welding area and resist environmental interference. Under normal conditions of interfering gas concentration, the ideal gas flow rate is usually 15L / min. The adjustment coefficient of wind speed to gas flow is used to quantify the impact of wind speed on gas flow, which is usually determined through experiments. The higher the wind speed, the larger the adjustment coefficient may need to be to compensate for the effect of wind speed on the dispersion of the shielding gas.

[0070] S2. Set the fluctuation range of the shielding gas flow rate, monitor the concentration of interfering gas in the closed air shaft during welding, adjust the flow rate of shielding gas related to gas shielded welding based on the concentration of interfering gas, and calculate the growth rate of the interfering gas concentration;

[0071] S21. Based on the reference gas flow rate and in combination with the economic benefits of the inert protective gas, the maximum protective gas flow rate is set, and the protective gas flow rate fluctuation range is calculated;

[0072] S211, obtain reference gas flow Q B , according to the type of inert gas used and the price of the relevant inert gas, set the maximum value of the protective gas flow rate and calculate the protective gas flow fluctuation range. The algorithm formula is:

[0073] Q max =Q B (1+β);

[0074] Among them, Q max represents the maximum protective gas flow rate, β represents the maximum flow rate factor, Q B represents the reference gas flow rate. The protective gas flow fluctuation range is set based on the maximum protective gas flow rate. The protective gas flow fluctuation range is [Q B ,Q max ];

[0075] It should be noted that the maximum flow rate factor needs to be set according to the requirements of the welding process and the economic benefits. The value is usually between 0.2 and 0.3, and can be flexibly set according to the actual pipe welding conditions in the closed air shaft.

[0076] S22. Obtain the total value of excessive concentration of interfering gases at the pipeline welding position through a gas analyzer, including oxygen concentration, carbon dioxide concentration, nitrogen concentration, nitrogen oxide concentration, ozone concentration, and carbon monoxide concentration, of which:

[0077] L 过 =L 总 -L 标 ;

[0078] Among them, L 过 is the total value of excess concentration of interfering gas, L总 Represents the total value of the interfering gas concentration, L 标 Represents the standard interfering gas concentration value;

[0079] It should be noted that the standard interference gas concentration value is the interference gas concentration value under normal conditions, that is, the interference gas concentration value that does not affect gas shielded welding. When the interference gas concentration value exceeds the standard interference gas concentration value, it is necessary to increase the flow rate of the shielding gas to ensure the welding quality. This value can be obtained through experiments or by consulting experts in related fields.

[0080] S23. According to the total value of the excessive concentration of the interfering gas, the flow rate of the shielding gas in the gas shielded welding process is synchronously adjusted.

[0081] S231. Collect the corresponding data of the historical flow rate of protective gas and the total value of the excessive concentration of interfering gas, and construct a regression model, the algorithm formula of which is:

[0082]

[0083] Among them, Y represents the protective gas adjustment flow rate, Q B represents the reference gas flow rate, λ represents the influence coefficient, L 过 It is the total value of excess concentration of interfering gas;

[0084] S232, set the time interval T, obtain the welding interference gas concentration value at the start position of the time interval and the welding interference gas concentration value at the end position of the time interval through the gas analyzer, and calculate the welding interference gas growth rate. The algorithm formula is:

[0085]

[0086] Among them, V 焊接 Represents the growth rate of welding interference gas, C 终点 Represents the welding interference gas concentration value at the end of the time interval, C 起点 Represents the welding interference gas concentration value at the starting position of the time interval.

[0087] It should be noted that by adjusting the flow rate of the shielding gas, the accumulation of interfering gases can be reduced, and the occurrence of welding defects such as porosity and slag inclusions can be reduced. By calculating the growth rate of welding interfering gases, it is convenient to regulate the exhaust efficiency of subsequent exhaust equipment to prevent the problem of unstable gas flow leading to a decrease in welding quality.

[0088] S3. When the protective gas flow reaches the peak value of the gas flow fluctuation range, the gas shielded welding operation is suspended, and the closed air shaft exhaust operation is concentrated at the same time, until the interference gas concentration drops to the welding threshold, and the welding operation is repeated;

[0089] S31. Compare the protective gas adjustment flow rate with the peak value of the gas flow fluctuation range, and adjust the gas shielded welding operation. The specific steps are as follows:

[0090] When Y≤Q max When , adjust the shielding gas flow rate to be consistent with the value of Y, and continue the gas shielded welding operation;

[0091] When Y>Q max When the gas shielded welding operation is stopped;

[0092] S32. After stopping the gas shielded welding operation, exhaust the inside of the closed air shaft through a portable exhaust device, and record the total value of the interfering gas concentration L through a gas analyzer. 总 ;

[0093] S33, set the welding threshold θ, based on the total value L of the interference gas concentration 总 , combined with the welding threshold θ for comparison, the specific steps are:

[0094] When L 总 ≤θ, continue the pipeline welding operation;

[0095] When L 总 >θ, continue to exhaust the air using the portable exhaust equipment.

[0096] It should be noted that by setting the welding threshold θ, it can be ensured that the concentration of interfering gas during pipeline welding meets the specific requirements of the welding operation, and through Q max Compared with Y, it can prevent the problem of excessive use of protective gas leading to reduced economic benefits.

[0097] S4. Combine the growth rate of the interfering gas concentration, the gas generation rate of the operator, and other gas sources to comprehensively calculate the growth rate of the total interfering gas concentration and set the exhaust rate of the exhaust equipment;

[0098] S41. When welding is stopped, let the operator place himself in a closed air shaft, collect the total gas concentration value C1 at time t1 and the total gas concentration value C2 at time t2 in the closed air shaft through a gas analyzer, and calculate the gas growth rate V of other gas sources. 其他 , and its algorithm formula is:

[0099]

[0100] S42, combined with other gas sources gas growth rate V 其他 The growth rate of welding interference gas V 焊接 , calculate the total interfering gas concentration growth rate V 总 , and its algorithm formula is:

[0101] V 总 =V 焊接 +V 其他 ;

[0102] S421, combined with the total interfering gas concentration growth rate V 总 Fluctuation range of protective gas flow

[0103] [Q B ,Q max ], set the continuous exhaust rate of the portable exhaust device, the specific steps are:

[0104] P=V 总 η;

[0105] Where P is the exhaust efficiency of the portable exhaust equipment, V 总 represents the growth rate of the total interfering gas concentration, and η represents the compensation interval.

[0106] It should be noted that η represents the compensation interval, and its value range is between η0 and 1.2. When η is η0, the value of the protective gas adjustment flow rate Y0 under the corresponding exhaust efficiency should be:

[0107]

[0108] The specific value can be flexibly selected according to the actual situation.

[0109] In summary, the present invention collects data inside the closed air shaft during gas shielded welding for pipeline welding inside the closed air shaft, and adjusts the flow rate of the shielding gas in the gas shielded welding process in real time in combination with the growth rate of the interfering gas to meet the welding needs. The real-time adjustment of the flow rate of the shielding gas can reduce the accumulation of the interfering gas and reduce the occurrence of welding defects such as pores and slag inclusions.

[0110] By combining the economic benefits of specific shielding gases and the economic benefits of related welding projects, the fluctuation range of shielding gas flow is set, and the maximum shielding gas flow rate caused by the accumulation of interfering gases in the closed air shaft is limited to avoid economic losses caused by excessive use of gas, so as to improve the overall economic benefits of the project. In addition, by comprehensively calculating the growth rate of interfering gas concentration inside the closed air shaft and the growth rate of other gas sources, the fluctuation range of shielding gas flow is comprehensively considered, and the appropriate exhaust rate of exhaust equipment is set to ensure that the shielding gas adjustment amount is within the range that meets the economic benefits and welding quality. At the same time, avoid the problem that excessive exhaust rate inside the closed air shaft causes gas pressure to decrease, making gas flow unstable and leading to reduced welding quality.

[0111] Based on the growth rate of the interfering gas concentration and the growth rate of other gas sources, a compensation interval is set to compensate for the exhaust efficiency of the exhaust equipment to prevent a large amount of air extraction from causing uneven distribution of gas inside the air shaft, affecting the uniform coverage of the protective gas at the welding site, and further improving the quality of the weld, so as to improve the quality of pipeline welding in closed air shafts.

[0112] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A closed air shaft pipeline welding process, characterized in that: The following steps are involved: S1. Collect the interfering gas data and gas flow data inside the closed air shaft, and calculate the reference gas flow rate of the protective gas; S11. Before welding the pipeline, use gas sensors and gas analyzers to collect data on the types of interfering gases in the closed air shaft. Interfering gases include oxygen, carbon dioxide, and nitrogen. S12. An anemometer is set at the welding position of the pipeline inside the closed air shaft to obtain the gas flow velocity V at the welding position. g ; S13. Calculate the inert gas reference gas flow rate according to the gas flow rate at the welding position. The specific algorithm formula is: Q B =Q i +α·V g ; Among them, Q B represents the reference gas flow rate, Q i Represents the ideal gas flow, that is, the gas flow usually set under standard conditions without wind or environmental interference, V g represents the measured gas flow velocity at the welding position, and α represents the adjustment coefficient of wind speed to gas flow; S2. Set the fluctuation range of the shielding gas flow rate, monitor the concentration of interfering gas in the closed air shaft during welding, adjust the flow rate of shielding gas related to gas shielded welding based on the concentration of interfering gas, and calculate the growth rate of the interfering gas concentration; S3. When the protective gas flow reaches the peak value of the gas flow fluctuation range, the gas shielded welding operation is suspended, and the closed air shaft exhaust operation is concentrated at the same time, until the interference gas concentration drops to the welding threshold, and the welding operation is repeated; S4. Combine the growth rate of the interfering gas concentration, the gas generation rate of the operator, and other gas sources to comprehensively calculate the growth rate of the total interfering gas concentration and set the exhaust rate of the exhaust equipment.

2. A closed air shaft pipeline welding process according to claim 1, characterized in that: The S2 comprises the following sub-steps: S21. Based on the reference gas flow rate and in combination with the economic benefits of the inert protective gas, the maximum protective gas flow rate is set, and the protective gas flow rate fluctuation range is calculated; S22. Obtain the total value of excessive concentration of interfering gases at the pipeline welding position through a gas analyzer, including oxygen concentration, carbon dioxide concentration, nitrogen concentration, nitrogen oxide concentration, ozone concentration, and carbon monoxide concentration, of which: L 过 =L 总 -L 标 ; Among them, L 过 is the total value of excess concentration of interfering gas, L 总 Represents the total value of the interfering gas concentration, L 标 Represents the standard interfering gas concentration value; S23. According to the total value of the excessive concentration of the interfering gas, the flow rate of the shielding gas in the gas shielded welding process is synchronously adjusted.

3. A closed air shaft pipeline welding process according to claim 2, characterized in that: The S21 includes the following sub-steps: S211. Obtaining reference gas flow rate Q B , according to the type of inert gas used and the price of the relevant inert gas, set the maximum value of the protective gas flow rate and calculate the protective gas flow fluctuation range. The algorithm formula is: Q max =Q B ·(1+β); Among them, Q max represents the maximum protective gas flow rate, β represents the maximum flow rate factor, Q B represents the reference gas flow rate. The protective gas flow fluctuation range is set based on the maximum protective gas flow rate. The protective gas flow fluctuation range is [Q B ,Q max ].

4. A closed air shaft pipeline welding process according to claim 3, characterized in that: The S23 comprises the following sub-steps: S231. Collect the corresponding data of the historical flow rate of protective gas and the total value of the excessive concentration of interfering gas, and construct a regression model, the algorithm formula of which is: Among them, Y represents the protective gas adjustment flow rate, Q B represents the reference gas flow rate, λ represents the influence coefficient, L 过 It is the total value of excess concentration of interfering gas; S232, set the time interval T, obtain the welding interference gas concentration value at the start position of the time interval and the welding interference gas concentration value at the end position of the time interval through the gas analyzer, and calculate the welding interference gas growth rate. The algorithm formula is: Among them, V 焊接 Represents the growth rate of welding interference gas, C 终点 Represents the welding interference gas concentration value at the end of the time interval, C 起点 Represents the welding interference gas concentration value at the starting position of the time interval.

5. A closed air shaft pipeline welding process according to claim 4, characterized in that: The S3 comprises the following sub-steps: S31. Compare the protective gas adjustment flow rate with the peak value of the gas flow fluctuation range, and adjust the gas shielded welding operation. The specific steps are as follows: When Y≤Q max When , adjust the shielding gas flow rate to be consistent with the value of Y, and continue the gas shielded welding operation; When Y>Q max When the gas shielded welding operation is stopped; S32. After stopping the gas shielded welding operation, exhaust the inside of the closed air shaft through a portable exhaust device, and record the total value of the interfering gas concentration L through a gas analyzer. 总 ; S33, set the welding threshold θ, based on the total value L of the interference gas concentration 总 , combined with the welding threshold θ for comparison, the specific steps are: When L 总 ≤θ, continue the pipeline welding operation; When L 总 >θ, continue to exhaust the air using the portable exhaust equipment.

6. A closed air shaft pipeline welding process according to claim 5, characterized in that: The S4 comprises the following sub-steps: S41. When welding is stopped, let the operator place himself in a closed air shaft, collect the total gas concentration value C1 at time t1 and the total gas concentration value C2 at time t2 in the closed air shaft through a gas analyzer, and calculate the gas growth rate V of other gas sources. 其他 , and its algorithm formula is: S42, combined with other gas sources gas growth rate V 其他 The growth rate of welding interference gas V 焊接 , calculate the total interfering gas concentration growth rate V 总 , and its algorithm formula is: V 总 =V 焊接 +V 其他 。 7. A closed air shaft pipeline welding process according to claim 6, characterized in that: The S42 also includes the following sub-steps: S421, combined with the total interfering gas concentration growth rate V 总 The fluctuation range of protective gas flow rate [Q B ,Q max ], set the continuous exhaust rate of the portable exhaust device, the specific steps are: P=V 总 ·or; Where P is the exhaust efficiency of the portable exhaust equipment, V 总 represents the growth rate of the total interfering gas concentration, and η represents the compensation interval.

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