Method and system for controlling high zinc coating weight of hot-dip galvanized steel pipe

Abstract

The application relates to the technical field of galvanizing steel pipes, and discloses a high-zinc-content control method and system for hot-dip galvanizing steel pipes. The method comprises the following steps: completely removing impurities and acid residues on the surface of the steel pipe by adopting a secondary pickling and secondary water washing pretreatment process, forming a uniform salt film to improve the wettability of the base body by means of solvent online treatment and a composite plating aid system, monitoring and regulating the content of alloy elements such as aluminum, nickel and magnesium in the zinc liquid in real time by means of a spectrometer, accurately controlling the zinc liquid temperature and zinc immersion time according to the pipe diameter and steel grade by querying a four-dimensional parameter database, dynamically adjusting the cooling time according to the pipe diameter in the post-processing stage, and controlling the distribution of iron-zinc compounds and iron-aluminum inhibition layers by means of metallographic structure detection, so that the high-zinc-content target is stably achieved. The application cooperatively controls the uniformity of the zinc liquid temperature by means of multi-point temperature measurement, dynamically adjusts the cooling time according to the pipe diameter, and adopts quantitative metallographic structure detection, so that the stable output capacity of the high-zinc-content and the consistency of the coating quality are improved.

Description

Technical Field

[0001] This application relates to the field of steel pipe galvanizing technology, and in particular to a method and system for controlling the high zinc coating amount of hot-dip galvanized steel pipes. Background Technology

[0002] As a key material in industrial production and infrastructure construction, the corrosion resistance of steel pipes directly affects their service life. Hot-dip galvanizing is a traditional mainstream process to improve the corrosion resistance of steel pipes. By immersing pre-treated steel pipes in high-temperature molten zinc, the zinc reacts with the steel pipe substrate to form a composite coating structure of zinc-iron alloy layer and pure zinc layer, thus giving the steel pipe excellent anti-corrosion performance. This process is widely used in pipelines, building supports, and other scenarios. The traditional hot-dip galvanizing process mainly includes pickling and washing in the pretreatment stage, fluxing treatment, the main hot-dip galvanizing process, and cooling and passivation in the post-treatment stage. Among them, the pickling process is used to remove oxide scale and rust from the surface of the steel pipe. The fluxing treatment enhances the wettability of the steel pipe with zinc liquid by forming a salt film on the surface of the steel pipe. The hot-dip galvanizing stage achieves the formation of zinc layer by controlling the zinc liquid temperature and immersion time. The post-treatment stage controls the microstructure of the alloy layer by cooling.

[0003] However, traditional hot-dip galvanizing processes still suffer from poor process stability in actual production. Insufficient precision control of zinc bath composition makes them susceptible to raw material impurities and temperature fluctuations, resulting in significant differences in zinc coating weight between different batches, making it difficult to consistently achieve the high zinc coating weight requirement of over 500 grams per square meter. The single pickling process in the pretreatment stage is insufficient to completely remove deep oxide scale, stubborn rust, and fine impurities from the steel pipe surface, and incomplete rinsing can lead to acid residue. These residues can cause defects such as pinholes and blistering in the subsequent galvanizing process, affecting the zinc coating weight and coating quality. The low activity and poor thermal stability of the flux salt film formation result in insufficient wettability of the substrate, leading to weak interfacial bonding between the steel pipe substrate and the zinc bath. After pickling, the iron elements on the steel pipe surface react with the zinc bath to easily generate excessive iron-zinc brittle intermetallic compounds. At the same time, the iron-aluminum intermetallic compound inhibition layer used to inhibit the formation of brittle compounds is unevenly distributed. These problems collectively lead to a decrease in coating toughness, affecting the service safety of the steel pipe. The traditional zinc chloride-ammonium chloride solvent system is prone to accumulating iron ions and oxide impurities during use, causing rapid decay of solvent activity and requiring frequent replacement, increasing production costs.

[0004] Further analysis revealed that when complex conditions such as fluctuations in zinc bath temperature, differences in steel pipe diameter, and variations in the composition of different steel grades occur, traditional processes lack a scientific parameter adaptive adjustment mechanism. The immersion time is difficult to precisely match actual needs, easily leading to problems such as excessively thick coatings resulting in waste or uneven coatings causing substandard quality. The root cause of this parameter mismatch lies in the failure to establish a correlation database between steel pipe specifications and process parameters, forcing operators to rely solely on experience and unable to achieve precise control. Furthermore, improper cooling rate control in the post-processing stage directly affects the microstructure of the alloy layer in the coating; excessively rapid cooling rates inhibit the full formation of the iron-aluminum intermetallic compound inhibition layer. The excessive content of iron-zinc brittle compounds leads to problems, while slow cooling rates prolong production cycles and reduce efficiency. However, in traditional processes, cooling time is often a fixed parameter and cannot be dynamically adjusted according to the heat capacity differences of the steel pipe diameter. More importantly, there is a lack of quantitative detection methods for the microstructure of the coating, making it impossible to accurately assess whether the content of iron-zinc compounds and the thickness of the iron-aluminum inhibitory layer meet quality requirements. This lack of quality control makes it difficult to detect and correct process deviations in a timely manner, ultimately resulting in poor coating quality consistency and unstable brittleness control in the finished steel pipes, making it difficult to meet the stringent requirements of high-reliability applications such as low-brittleness conveying steel pipes. Summary of the Invention

[0005] This application provides a method and system for controlling high zinc coating amount in hot-dip galvanized steel pipes. It addresses the problems of poor process stability, inadequate pretreatment, parameter mismatch, inaccurate cooling control, and lack of quantitative microstructure detection in traditional hot-dip galvanizing processes, which lead to large fluctuations in zinc coating amount, unstable coating quality, and difficulty in controlling the content of brittle compounds. By establishing a four-dimensional parameter database to achieve precise matching between steel pipe specifications and process parameters, by using multi-point temperature measurement to collaboratively control the uniformity of zinc bath temperature, and by dynamically adjusting cooling time according to pipe diameter and employing quantitative microstructure detection, the stable output capability of high zinc coating amount and the consistency of coating quality are improved.

[0006] In a first aspect, this application provides a method for controlling the high zinc coating amount of hot-dip galvanized steel pipes, the method comprising:

[0007] Step S1: The steel pipe is subjected to a first pickling with hydrochloric acid with a mass fraction between 18% and 22%, a first water wash with running water, a second pickling with hydrochloric acid with a mass fraction between 8% and 12% and surfactant, and a second water wash with deionized water to obtain the pretreated steel pipe substrate.

[0008] Step S2: Immerse the pretreated steel pipe substrate in a zinc chloride-ammonium chloride solvent that has undergone ion exchange iron removal and pressure filtration separation, then immerse it in a composite flux containing potassium fluoroborate and nickel nitrate and dry it in a drying oven to obtain a steel pipe with a salt film covering its surface.

[0009] Step S3: Monitor the mass fractions of aluminum, nickel, and magnesium in the zinc bath in real time using a spectrometer. Determine the amount of each alloying element to be added based on the difference between the target mass fraction and the current mass fraction, as well as the total mass of the zinc bath. Add the materials and stir to obtain a zinc bath with alloying element content that meets the standards.

[0010] Step S4: Based on the pipe diameter and steel grade, query the corresponding zinc bath temperature and immersion time from the preset four-dimensional parameter database, immerse the steel pipe with the salt film covering the surface into the zinc bath with the alloy element content meeting the standard, and combine with the internal blowing process to obtain the galvanized steel pipe.

[0011] Step S5: The galvanized steel pipe is sequentially subjected to rotary air cooling to an intermediate temperature and then to deionized water with added corrosion inhibitor to room temperature. The air cooling time is adjusted according to the pipe diameter to control the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer, thus obtaining the finished galvanized steel pipe.

[0012] Secondly, this application provides a high zinc coating control system for hot-dip galvanized steel pipes, the high zinc coating control system comprising:

[0013] The processing module is used to sequentially perform a first pickling with hydrochloric acid with a mass fraction between 18% and 22%, a first water wash with flowing water, a second pickling with hydrochloric acid with a mass fraction between 8% and 12% and surfactant, and a second water wash with deionized water to obtain a pretreated steel pipe substrate.

[0014] The immersion module is used to immerse the pretreated steel pipe substrate in a zinc chloride-ammonium chloride solvent that has undergone ion exchange iron removal and pressure filtration separation, and then immerse it in a composite flux containing potassium fluoroborate and nickel nitrate and dry it in a drying oven to obtain a steel pipe with a salt film covering its surface.

[0015] The stirring module is used to monitor the mass fractions of aluminum, nickel, and magnesium in the zinc bath in real time using a spectrometer. Based on the difference between the target mass fraction and the current mass fraction, as well as the total mass of the zinc bath, the amount of each alloying element to be added is determined and stirred to obtain a zinc bath with the alloying element content meeting the standard.

[0016] The internal blowing module is used to query the corresponding zinc bath temperature and immersion time from a preset four-dimensional parameter database according to the steel pipe diameter and steel type, immerse the steel pipe with the salt film covering the surface into the zinc bath with the alloy element content meeting the standard, and combine it with the internal blowing process to obtain the galvanized steel pipe.

[0017] The control module is used to sequentially perform rotary air cooling to an intermediate temperature and deionized water cooling with added corrosion inhibitor to room temperature on the galvanized steel pipe. The air cooling time is adjusted according to the pipe diameter to control the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer, so as to obtain the finished galvanized steel pipe.

[0018] Thirdly, a high zinc coating amount control device for hot-dip galvanized steel pipes is provided, comprising: a memory and at least one processor, wherein the memory stores instructions; the at least one processor invokes the instructions in the memory to cause the high zinc coating amount control device for hot-dip galvanized steel pipes to execute the above-described high zinc coating amount control method for hot-dip galvanized steel pipes.

[0019] Fourthly, a computer-readable storage medium is provided, wherein instructions are stored therein, which, when executed on a computer, cause the computer to perform the above-described method for controlling the high zinc content of hot-dip galvanized steel pipes.

[0020] The technical solution provided in this application fundamentally solves the core problems of poor process stability, inadequate pretreatment effect, and parameter control imbalance in traditional hot-dip galvanizing processes by adopting a technical approach combining four-dimensional collaborative parameter matching and spectral monitoring. Through a multi-stage pretreatment system of "pickling-water washing-secondary pickling-secondary water washing," a primary pickling process using a hydrochloric acid solution with a mass fraction between 18% and 22% and a corrosion inhibitor thoroughly removes thick oxide scale and large-area rust from the steel pipe surface. A secondary water washing process, combining flowing water spraying and immersion, initially removes acid residue. A secondary pickling process using a hydrochloric acid solution with a mass fraction between 8% and 12% and a surfactant further refines the removal of residual fine oxide spots and stubborn rust. Finally, a secondary water washing process, combining flowing water immersion and deionized water spraying, thoroughly removes acid and corrosion inhibitor residue. This graded pretreatment system... This system significantly improves the cleanliness of the steel pipe substrate and greatly reduces the acid residue rate, effectively avoiding defects such as pinholes and blistering in the coating caused by surface impurities and acid residue during subsequent galvanizing. It establishes the basic conditions for stable output of high zinc coating. At the same time, the online solvent treatment system uses iron removal devices, oxidation removal, and pressure filtration separation processes to control the iron ion and oxide content in the solvent in real time, maintaining the stability of the mass fraction of zinc chloride and ammonium chloride, extending the effective service life of the solvent, and reducing production costs. The intelligent composite flux system uses a two-component synergistic formula to compound zinc chloride, ammonium chloride, potassium fluoroborate, and nickel nitrate. With temperature-composition linkage control, the flux concentration is monitored and adjusted in real time to ensure the formation of a uniform, dense, and thermally stable salt film on the steel pipe surface. This significantly improves the wettability and interfacial bonding between the substrate and the zinc liquid, solving the technical defects of low activity and unstable salt film quality of traditional fluxes.

[0021] In the core stage of hot-dip galvanizing, the composition of the zinc bath is monitored in real time using spectral technology. This allows for precise control of the content errors of alloying elements such as industrial pure zinc, aluminum, nickel, and magnesium, ensuring the stability of the zinc bath composition. Aluminum is used to inhibit excessive formation of iron-zinc compounds, reducing coating brittleness; nickel improves the crystal structure of the alloy layer, enhancing coating toughness; and magnesium improves the fluidity of the zinc bath, ensuring uniform zinc coating on the inner wall of the steel pipe. A four-dimensional parameter database is established, using the steel pipe diameter and steel type as query conditions to match corresponding zinc bath temperature and immersion time settings. This achieves precise adaptation of process parameters to the steel pipe specifications. The zinc bath temperature is controlled collaboratively by a gas heating system and an electric heating system. Multi-point temperature measurement is used to collect temperature data from different locations, calculate the average temperature value, and perform temperature compensation adjustments, eliminating the problem of uneven zinc bath temperature distribution and ensuring that the steel pipe completes the galvanizing process under optimal temperature conditions. An intelligent crane system precisely controls the immersion time of the steel pipe according to the immersion time setting, avoiding uneven coating thickness or insufficient zinc coating caused by excessively long or short immersion times. The internal blowing process blows heated pressure to the set temperature onto the inner wall of the steel pipe. Excess zinc liquid is blown out by compressed air, achieving uniform control of the zinc layer thickness inside the pipe. In the post-processing stage, the air cooling time parameters are determined according to the pipe diameter. Rotary air cooling treatment is used to uniformly reduce the surface temperature of the steel pipe to the intermediate temperature, avoiding the problem of excessive temperature difference between the upper and lower surfaces caused by static cooling. Deionized water with added benzotriazole corrosion inhibitor is used for water cooling treatment, which prevents oxidation of the zinc layer surface while rapidly cooling to room temperature. Metallographic analysis is used to collect data on the mass fraction of iron and zinc compounds in the coating and the thickness of the iron-aluminum intermetallic compound inhibition layer to form coating microstructure parameters. The microstructure quality of the coating is judged according to the set range, realizing quantitative assessment of coating brittleness control. This ensures that the content of iron and zinc brittle compounds is controlled within a reasonable range and that the iron-aluminum inhibition layer is uniformly distributed, significantly improving the toughness and impact resistance of the coating. The overall process, through multi-dimensional technical collaboration and composition-structure innovation, achieves stable output of high zinc content, consistent control of coating quality, and effective reduction of production costs, meeting the stringent requirements of high-reliability applications such as low-brittleness conveying steel pipes. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of one embodiment of the method for controlling the high zinc coating amount of hot-dip galvanized steel pipes in this application;

[0024] Figure 2This is a schematic diagram illustrating the control range of zinc liquid alloy element mass fraction in the embodiments of this application;

[0025] Figure 3 This is a schematic diagram of one embodiment of the high zinc coating control system for hot-dip galvanized steel pipes in this application.

[0026] Figure 4 This is a schematic block diagram of the structure of the high zinc coating amount control device for hot-dip galvanized steel pipes in an embodiment of the present invention. Detailed Implementation

[0027] This application provides a method and system for controlling the zinc coating amount of hot-dip galvanized steel pipes. The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms "comprising" or "having" and any variations thereof are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0028] For ease of understanding, the specific process of the embodiments of this application is described below. Please refer to [link / reference]. Figure 1 One embodiment of the method for controlling the zinc coating amount of hot-dip galvanized steel pipes in this application includes:

[0029] Step S1: The steel pipe is subjected to a first pickling with hydrochloric acid with a mass fraction between 18% and 22%, a first water wash with running water, a second pickling with hydrochloric acid with a mass fraction between 8% and 12% and surfactant, and a second water wash with deionized water to obtain the pretreated steel pipe substrate.

[0030] Step S2: The pretreated steel pipe substrate is immersed in zinc chloride-ammonium chloride solvent that has undergone ion exchange iron removal and pressure filtration separation, and then immersed in a composite flux containing potassium fluoroborate and nickel nitrate and dried in a drying oven to obtain a steel pipe with a salt film on the surface.

[0031] Step S3: Monitor the mass fractions of aluminum, nickel, and magnesium in the zinc bath in real time using a spectrometer. Determine the amount of each alloying element to be added based on the difference between the target mass fraction and the current mass fraction, as well as the total mass of the zinc bath. Add the materials and stir to obtain a zinc bath with alloying element content that meets the standards.

[0032] Step S4: Based on the pipe diameter and steel grade, query the corresponding zinc bath temperature and immersion time from the preset four-dimensional parameter database, immerse the steel pipe with the salt film covering the surface into the zinc bath with the alloy element content meeting the standard, and combine it with the internal blowing process to obtain the galvanized steel pipe.

[0033] Step S5: After galvanizing, the steel pipe is sequentially subjected to rotary air cooling to the intermediate temperature and then cooling to room temperature with deionized water containing corrosion inhibitor. The air cooling time is adjusted according to the pipe diameter to control the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer, thus obtaining the finished galvanized steel pipe.

[0034] It is understood that the executing entity of this application can be a high zinc coating control system for hot-dip galvanized steel pipes, or it can be a terminal or a server; the specific implementation is not limited here. This application's embodiment uses a server as an example for illustration.

[0035] Specifically, a four-stage pretreatment system is used to achieve deep cleaning of the steel pipe substrate. First, the pickling process parameters are selected according to the steel type. For Q235 steel pipes, a hydrochloric acid solution with a mass fraction of 18% to 22% is prepared, and a hexamethylenetetramine corrosion inhibitor with a mass fraction of 0.3% to 0.5% is added. The acid solution temperature is controlled at 45℃ to 50℃, and the steel pipe is immersed in it for 60 to 65 seconds to remove the thick oxide scale and large-area rust from the surface. Then, the steel pipe is taken out and sprayed with running water for 10 to 15 minutes to rinse off the acid residue on the surface. Then, it is soaked for 8 to 12 minutes, and the steel pipe is moved up and down by an overhead crane and stirred back and forth in the water more than 20 times. At the same time, the steel pipe is tilted to control the water to ensure that the acid residue on the inner and outer walls is removed. After the first water rinse, the pH value of the steel pipe surface is controlled at 3 to 4. Then, the steel pipe is immersed in a solution of hydrochloric acid with a mass fraction of 8% to 12%, and a hexamethylenetetramine corrosion inhibitor with a mass fraction of 0.3% to 0.5% is added. In a low-concentration acid solution containing 0.2% to 0.4% hexamethylenetetramine corrosion inhibitor and 0.1% to 0.2% sodium dodecylbenzenesulfonate surfactant, the acid solution temperature is controlled at 35°C to 40°C. After soaking for 6 to 8 minutes, a second acid pickling process is performed to finely remove residual small oxide spots. After the second acid pickling, the pipe is first soaked in running water for 18 to 22 minutes, and then sprayed with deionized water for 8 to 12 minutes. The corrosion inhibitor and surfactant residues are thoroughly removed by agitation with an overhead crane and water control by tilting the pipe. After the second water wash, the pH value of the steel pipe surface is precisely controlled at 6.5 to 7 and the conductivity is reduced to below 30 microsiemens per centimeter. The combination of high-concentration initial removal and low-concentration fine removal acid pickling, along with running water rinsing and deionized water fine washing, significantly improves the cleanliness of the steel pipe substrate surface and reduces the acid residue rate to below 0.1%.

[0036] A highly active salt film is formed through online solvent treatment and intelligent control of composite flux. The pretreated steel pipe substrate is immersed in a solvent with a zinc chloride content of 110-140 g / L and an ammonium chloride content of 220-240 g / L. The solvent is purified in real time through an online treatment system. First, ferrous ions in the solvent are removed by a strong acidic cation exchange resin in an ion exchange iron removal device, allowing them to be captured by the resin. Then, compressed air is introduced into the solvent to oxidize the remaining ferrous ions to ferric ions. Next, a plate and frame filter press is used for pressure filtration, with a filtration accuracy set to 5-10 microns, to completely separate ferric hydroxide precipitates and suspended oxides. After online treatment, the ferric ion content in the solvent is controlled below 0.3%, and the oxide content is controlled below 0.1%. After the pipe is immersed in the solvent for 10 to 15 minutes to complete the purification process, it is taken out and immersed in a composite flux solution. The flux solution is formulated with 20% to 22% zinc chloride, 5% to 7% ammonium chloride, 0.3% to 0.5% potassium fluoroborate, and 0.2% to 0.4% nickel nitrate by mass fraction. The temperature of the flux solution is precisely maintained at 55°C to 60°C by an intelligent temperature control system. At the same time, an online concentration monitor is configured to monitor the concentration of zinc chloride and ammonium chloride in real time. When the concentration of zinc chloride is lower than 20% or the concentration of ammonium chloride is lower than 5%, the replenishment device is automatically triggered to replenish the solution according to the preset ratio. After the steel pipe is immersed in the flux solution for 8 to 12 minutes, it is taken out, drained, and sent to a 60°C drying oven to dry for 15 to 20 minutes to form a uniform and dense salt film layer with a thickness of 8 to 12 micrometers on the surface of the steel pipe.

[0037] Precise control of alloying elements in molten zinc is achieved through spectral monitoring and dynamic composition regulation. A spark direct-reading spectrometer is installed on the side wall of the zinc pot. The spectrometer probe is immersed 50 to 80 mm below the surface of the molten zinc and automatically performs composition detection every 30 minutes. The spectrometer uses vacuum ultraviolet spectroscopy to detect the current mass fraction of aluminum, nickel, and magnesium in the molten zinc. After detection, the difference between the current mass fraction of each element and its corresponding target mass fraction is calculated to obtain the mass fraction difference of each alloying element. The target mass fraction of aluminum is 0.020%, that of nickel is 0.10%, and that of magnesium is 0.04%. Subsequently, the mass fraction difference of each alloying element is multiplied by the amount of molten zinc. The total mass is used to calculate the additional amounts of aluminum ingots, nickel blocks, and magnesium ingots. After transmitting the data of each alloy element's additional amount to the central control system, the aluminum ingot feeding device, nickel block feeding device, and magnesium ingot feeding device are started automatically for feeding. After feeding is completed, the zinc liquid is thoroughly mixed by an electromagnetic stirring device. The stirring time is set to 8 to 10 minutes and the stirring frequency is 15 to 20 Hz to ensure that the added alloy elements are evenly dispersed in the zinc liquid. After uniform mixing, the spectrometer is used again to detect the composition to confirm that the mass fraction error of aluminum element is controlled within ±0.008%, the mass fraction error of nickel element is controlled within ±0.010%, and the mass fraction error of magnesium element is controlled within ±0.005%.

[0038] Precise hot-dip galvanizing of steel pipes is achieved through four-dimensional parameter database matching and internal blowing process control. The system uses pipe diameter and steel type as query criteria to match and retrieve the corresponding zinc bath temperature and immersion time settings from the four-dimensional parameter database. This database stores process parameters for different pipe diameters and steel types. Based on the zinc bath temperature settings, a gas-fired heating system and an electric heating system work together to control the zinc bath temperature. Five thermocouple temperature sensors are evenly distributed within the zinc pot to collect temperature data at each measuring point in real time and calculate the average temperature value. If the average temperature value deviates from the target temperature by more than 2°C... The power of the electric heating rod is automatically adjusted to compensate for temperature changes and ensure the zinc bath temperature reaches the standard. The steel pipe with a salt film on its surface is then immersed in the zinc bath at the standard temperature. The immersion time is controlled by an intelligent crane system according to the set zinc immersion time to obtain the zinc-treated steel pipe. After zinc immersion, the steel pipe undergoes an internal blowing process. The internal blowing head moves linearly inside the steel pipe and blows compressed air heated to 370°C to 450°C by a pipeline steam electric heating device onto the inner wall of the steel pipe. The compressed air pressure is controlled at 0.4 to 0.6 MPa and the internal blowing time is 15 to 25 seconds to blow out excess zinc bath from the inner wall of the steel pipe, so that the zinc content on the inner wall is uniform.

[0039] Gradient cooling and alloy layer control are used to suppress coating brittleness and optimize microstructure. Based on the pipe diameter, air cooling time parameters are determined for rotary air cooling of the galvanized steel pipe. The pipe is slowly rotated at 5 to 8 revolutions per minute to ensure consistent cooling rates across the pipe surface. During air cooling, the surface temperature of the pipe is reduced from the zinc melt temperature to an intermediate temperature of 300°C to 320°C. For 80mm diameter pipes, the air cooling time is set to 7 to 10 minutes. During air cooling, aluminum in the zinc melt diffuses and reacts with iron on the pipe surface to form an iron-aluminum intermetallic compound inhibition layer, preventing further diffusion of iron into the zinc layer and thus inhibiting the excessive formation of iron-zinc brittle compounds. After the temperature drops to an intermediate level, the steel pipe is immediately immersed in deionized water containing 0.8% to 1.2% benzotriazole corrosion inhibitor for water cooling treatment to bring the steel pipe temperature down to room temperature. The deionized water temperature is controlled between 15°C and 25°C, and the water cooling time for 80 mm diameter steel pipes is 3 to 4 minutes. After water cooling, the metallographic structure of the steel pipe coating is examined using a scanning electron microscope to observe the coating cross-section and collect data on the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer. Through gradient cooling, the mass fraction of iron-zinc brittle compounds in the coating is controlled within the range of 5% to 8%, and the thickness of the iron-aluminum intermetallic compound inhibition layer is controlled within the range of 1.5 to 2.5 micrometers with a uniformity of over 90%.

[0040] In one specific embodiment, step S1 includes:

[0041] Select the corresponding pickling process parameters according to the steel type of the steel pipe, immerse the steel pipe in a prepared hydrochloric acid solution with a mass fraction between 18% and 22% for a first pickling treatment, and obtain a steel pipe with surface oxide scale and rust removed.

[0042] The steel pipes with surface oxide scale and rust removed are first sprayed with running water and then soaked in running water. During the soaking process, the steel pipes are moved up and down by an overhead crane, agitated back and forth in the water, and the steel pipes are tilted to drain the water, resulting in a steel pipe after one water washing.

[0043] After the first water washing, the steel pipe is immersed in a hydrochloric acid solution containing hexamethylenetetramine corrosion inhibitor and sodium dodecylbenzenesulfonate surfactant at a mass fraction of 8% to 12% for a second pickling treatment, resulting in a steel pipe with the removal of residual oxide spots and stubborn rust.

[0044] The steel pipes with residual oxide spots and stubborn rust removed are first soaked in running water and then sprayed with deionized water. During the soaking process, the steel pipes are moved up and down by an overhead crane, agitated back and forth in the water, and the steel pipes are tilted to control the water, resulting in the pre-treated steel pipe substrate.

[0045] Specifically, when selecting the corresponding primary pickling process parameters based on the steel type of the steel pipe, parameter adaptation is performed to address the differences in chemical composition and surface condition of different steel types. For Q195 low-carbon steel pipes, a hydrochloric acid solution with a mass fraction of 18% to 20% is prepared, and a hexamethylenetetramine corrosion inhibitor with a mass fraction of 0.3% to 0.5% is added. The acid solution temperature is controlled within the range of 45℃ to 50℃, and the immersion time is set to 55 seconds. For Q235 low-carbon steel pipes, a hydrochloric acid solution with a mass fraction of 18% to 22% is prepared, and a hexamethylenetetramine corrosion inhibitor with a mass fraction of 0.3% to 0.5% is added. With 0.5% hexamethylenetetramine corrosion inhibitor, the acid solution temperature is controlled within the range of 45℃ to 50℃, and the immersion time is set to 60 to 65 seconds. For Q355 medium carbon steel pipes, a hydrochloric acid solution with a mass fraction of 18% to 20% is prepared, and 0.5% to 0.8% hexamethylenetetramine corrosion inhibitor is added. The acid solution temperature is reduced to the range of 40℃ to 45℃, and the immersion time is extended to 70 to 75 seconds. Through steel type adaptation, the targeted removal of oxide scale and rust layers on the surface of different steel types is achieved, while avoiding excessive corrosion of the medium carbon steel substrate by high concentration acid solution. When washing steel pipes to remove surface oxide scale and rust, a combination of spraying and immersion is used. First, the surface of the steel pipe is sprayed with flowing clean water at a pressure of 0.2 to 0.3 MPa for 10 to 15 minutes. During the spraying process, the water flow impacts the surface of the steel pipe, washing away the attached acid and loose rust. After spraying, the steel pipe is immersed in a flowing clean water tank for 8 to 12 minutes. During the immersion process, the steel pipe is moved up and down using an overhead crane and agitated back and forth in the water more than 20 times. The agitation ensures that the inner and outer walls of the steel pipe are in full contact with the clean water. At the same time, the steel pipe is tilted at an angle of about 30 to 45 degrees to allow the water accumulated on the inner wall to flow out from the pipe opening. Through the combination of overhead crane agitation and tilting to control water, the residual acid on the surface and inner wall of the steel pipe is thoroughly removed. After the first water wash, the pH value of the steel pipe surface is tested with pH test paper to confirm that the pH value is within the range of 3 to 4. When immersing steel pipes after a first water wash into a hydrochloric acid solution containing 8% to 12% hexamethylenetetramine corrosion inhibitor and sodium dodecylbenzenesulfonate surfactant for a second pickling, 0.2% to 0.4% hexamethylenetetramine corrosion inhibitor and 0.1% to 0.2% sodium dodecylbenzenesulfonate surfactant are added to the 8% to 12% hydrochloric acid solution. During the pickling process, the hexamethylenetetramine corrosion inhibitor adsorbs onto the surface of the steel pipe to form a protective film, slowing down the corrosion of the metal substrate by the acid. The sodium dodecylbenzenesulfonate surfactant reduces the surface tension of the acid solution and enhances its penetration ability into the surface of the steel pipe, allowing the acid solution to penetrate deep into the fine oxide spots and stubborn rust layers. The acid solution temperature is controlled within the range of 35°C to 40°C, and the immersion time is set to 6 to 8 minutes. Compared with the high concentration and long time of the first pickling, the second pickling uses a low concentration and short time for a refined treatment method to specifically remove the fine oxide spots and stubborn rust remaining after the first pickling.When performing a second water wash on steel pipes to remove residual oxide spots and stubborn rust, the pipes are first soaked in running water and then sprayed with deionized water. The steel pipes are first immersed in a flowing clean water tank for 18 to 22 minutes. During this soaking process, the pipes are moved up and down using an overhead crane and agitated in the water more than 20 times, while the pipes are tilted to drain the water. Soaking in running water removes corrosion inhibitors and surfactants adhering to the surface of the steel pipes. Then, deionized water is sprayed onto the surface of the steel pipes. The deionized water undergoes ion exchange treatment to remove metal ions such as calcium and magnesium, as well as anions such as chloride and sulfate ions. The spraying pressure is controlled at 0.25 to 0.35 MPa, and the spraying time is 8 to 12 minutes. The deionized water spray thoroughly cleans away any trace amounts of corrosion inhibitors, surfactants, and salts remaining on the surface of the steel pipes. After the second water wash, pH test paper is used to check the pH value of the steel pipe surface to confirm that the pH value is within the range of 6.5 to 7. Simultaneously, a conductivity meter is used to check the conductivity of the water film on the steel pipe surface to confirm that the conductivity has dropped below 30 microsiemens per centimeter.

[0046] In one specific embodiment, step S2 includes:

[0047] The pretreated steel pipe substrate is immersed in zinc chloride-ammonium chloride solvent. The ferrous ions in the solvent are removed by an ion exchange iron removal device. Then, the residual ferrous ions are oxidized to ferric ions by passing compressed air into the solvent. Subsequently, the ferric hydroxide precipitate and suspended oxides are separated by a plate and frame filter press to obtain the purified steel pipe substrate.

[0048] The purified steel pipe substrate is immersed in a composite flux solution containing zinc chloride, ammonium chloride, potassium fluoroborate and nickel nitrate. The temperature of the flux solution is maintained by an intelligent temperature control system and the concentration of zinc chloride and ammonium chloride is monitored in real time by an online concentration monitor to trigger automatic replenishment, thus obtaining a steel pipe after being immersed in the flux.

[0049] After the steel pipe is soaked in the flux, it is taken out and drained, and then sent to the drying kiln for drying treatment, so that a uniform and dense flux salt film layer is formed on the surface of the steel pipe, and a steel pipe with a surface covered with a flux salt film layer is obtained.

[0050] The thickness and coverage of the salt film on the surface of the steel pipe are tested. After confirming that the thickness of the salt film is within the set range and the coverage meets the standard, the steel pipe with the salt film on the surface is output.

[0051] Specifically, when the pretreated steel pipe substrate is immersed in a zinc chloride-ammonium chloride solvent for solvent treatment, the mass fraction of zinc chloride in the solvent is controlled within the range of 110 to 140 g / L, the mass fraction of ammonium chloride is controlled within the range of 220 to 240 g / L, and the solvent temperature is maintained at 50°C to 55°C. During the immersion of the steel pipe in the solvent, the solvent is purified in real time through an online treatment system. The ion exchange iron removal device uses a strongly acidic cation exchange resin filled in the exchange column. The solvent is drawn through a circulation pump and flows through the exchange column. Hydrogen ions in the resin exchange with ferrous ions in the solvent. Ferrous ions are captured by the resin while hydrogen ions are released into the solvent. After ion exchange treatment, the concentration of ferrous ions in the solvent is greatly reduced, but residual ferrous ions still exist. Subsequently, compressed air is introduced into the solvent after ion exchange treatment. The oxygen in the compressed air reacts with the residual ferrous ions in the solvent. In the oxidation reaction, ferrous ions lose one electron and become ferric ions. These ferric ions combine with hydroxide ions in the alkaline environment of the solvent to form ferric hydroxide precipitate. Simultaneously, chlorite ions in the solvent are oxidized to chlorate ions by oxygen. After the oxidation reaction, the solvent contains ferric hydroxide precipitate and other suspended oxides. The solvent then flows into a plate and frame filter press for solid-liquid separation. The plate and frame filter press consists of multiple layers of filter plates and frames arranged alternately. The surface of the filter plates is covered with filter cloth. Under pressure, the solvent passes through the filter cloth, and solid particles are trapped on the surface of the filter cloth to form a filter cake. The filtration accuracy is set to 5 to 10 microns to completely separate the ferric hydroxide precipitate and suspended oxides. After three-stage purification treatment by the online treatment system, the ferric ion content in the solvent is reduced to below 0.3%, and the oxide content is reduced to below 0.1%. The steel pipe is then immersed in the purified solvent for 10 to 15 minutes to complete the solvent treatment.After purification and draining, the steel pipe substrate is immersed in a composite flux solution. The composite flux solution is prepared by first dissolving zinc chloride and ammonium chloride in deionized water according to their mass fractions to obtain a basic flux solution. The mass fraction of zinc chloride is controlled within the range of 20% to 22%, and the mass fraction of ammonium chloride is controlled within the range of 5% to 7%. Then, potassium fluoroborate and nickel nitrate are added to the basic flux solution. The mass fraction of potassium fluoroborate is controlled within the range of 0.3% to 0.5%, and the mass fraction of nickel nitrate is controlled within the range of 0.2% to 0.4%. Potassium fluoroborate in the flux solution lowers the melting temperature of the salt film, which is crucial for subsequent hot-dip galvanizing. The process requires melting at high temperatures. Adding potassium fluoroborate lowers the melting temperature of the salt film from the traditional 420℃ to approximately 380℃. Nickel nitrate in the flux enhances the wettability of the steel pipe substrate with the zinc bath. Upon dissolution, nickel nitrate releases nickel ions, which adsorb onto the surface of the steel pipe substrate, forming a nickel ion adsorption layer. This layer reduces the interfacial tension between the steel pipe surface and the zinc bath. The prepared composite flux solution is kept at a constant temperature by an intelligent temperature control system. This system includes a heating device, a temperature sensor, and a controller. The temperature sensor collects the flux solution temperature data in real time and transmits it to the controller, which employs a PID closed-loop control. The loop control algorithm calculates the power output of the heating device based on the deviation between the setpoint and the actual temperature. The PID algorithm includes three control links: proportional, integral, and derivative. The proportional link calculates the control quantity based on the current temperature deviation, the integral link calculates the control quantity based on the cumulative historical temperature deviation to eliminate steady-state error, and the derivative link calculates the control quantity based on the rate of change of the temperature deviation to suppress temperature overshoot. After PID algorithm control, the temperature of the flux solution is precisely maintained within the range of 55℃ to 60℃, and the temperature fluctuation is controlled within ±0.5℃. Simultaneously, an online concentration monitor monitors the concentration of zinc chloride and ammonium chloride in the flux solution in real time. The conductivity monitor uses the conductivity measurement principle. The conductivity of a solution is directly proportional to the ion concentration in the solution. By measuring the conductivity of the solution and combining it with a temperature compensation algorithm, the actual concentrations of zinc chloride and ammonium chloride are calculated. When the zinc chloride concentration is detected to be below 20%, the controller automatically starts the zinc chloride replenishment pump to replenish zinc chloride solution to the flux solution. When the ammonium chloride concentration is detected to be below 5%, the controller automatically starts the ammonium chloride replenishment pump to replenish ammonium chloride solution to the flux solution. The running time of the replenishment pump is calculated based on the difference between the current concentration and the target concentration and the total volume of the flux solution. The steel pipe is immersed in the composite flux solution for 8 to 12 minutes.After the steel pipe is immersed in the flux solution, it is first drained. During draining, the steel pipe is tilted to allow excess flux solution on the surface to flow back into the flux tank. The draining time is 2 to 3 minutes. Then, the steel pipe is sent to a drying kiln for drying. The internal temperature of the drying kiln is controlled at 60℃. The steel pipe stays in the drying kiln for 15 to 20 minutes. During the drying process, the water in the flux solution adhering to the surface of the steel pipe gradually evaporates. Components such as zinc chloride, ammonium chloride, potassium fluoroborate, and nickel nitrate crystallize and precipitate on the surface of the steel pipe to form a solid salt film layer. The thickness of the salt film layer is related to the amount of flux solution adhering to the surface of the steel pipe and the drying time. By controlling the immersion time and draining time, the amount of flux solution adhering to the surface of the steel pipe is adjusted. By controlling the temperature of the drying kiln and the drying time, the rate of water evaporation is adjusted. Finally, a uniform and dense salt film layer with a thickness of 8 to 12 micrometers is formed on the surface of the steel pipe. The salt film layer is white or light gray and covers the inner and outer surfaces of the steel pipe. When inspecting the quality of steel pipes covered with a salt coating, the thickness of the salt coating is measured first. Eight measurement points are evenly selected on the steel pipe surface using a coating thickness gauge. These points are located at 0°, 45°, 90°, 135°, 180°, 225°, 270°, and 315° on the outer wall of the steel pipe, and at the center point on the inner wall. The coating thickness gauge uses the principle of electromagnetic induction to measure the thickness of a non-magnetic coating on a magnetic substrate. When the gauge probe contacts the steel pipe surface, it generates an alternating magnetic field. This magnetic field induces eddy currents in the steel pipe substrate. The intensity of these eddy currents is related to the coating thickness. The salt coating thickness is calculated by measuring the intensity of the eddy current signal. The thickness of the coating is then recorded at the eight measurement points. The average thickness of the salt film is obtained by averaging the measurement data. At the same time, the deviation between the thickness of each measurement point and the average thickness is calculated. The average thickness of the salt film is required to be within the range of 8 to 12 micrometers and the thickness deviation of each point is not more than 15% of the average thickness. Then, the salt film coverage is tested. The integrity of the salt film on the surface of the steel pipe is observed using a magnifying glass or microscope to check for defects such as missed coating, peeling, and cracks. The surface of the steel pipe is divided into several inspection areas, and the salt film status of each area is checked one by one. The salt film coverage is required to reach 100% with no missed coating or peeling. When the salt film thickness and coverage test results meet the requirements, the steel pipe passes the quality inspection and enters the next process.

[0052] In one specific embodiment, step S3 includes:

[0053] The current mass fractions of aluminum, nickel, and magnesium in the zinc melt were detected by spark direct-reading spectrometer to obtain the current composition data of the zinc melt alloy elements.

[0054] The difference between the current mass fraction of each element in the current composition data of zinc liquid alloy elements and the corresponding target mass fraction is calculated to obtain the mass fraction difference of each alloy element.

[0055] The replenishment amounts are calculated by multiplying the mass fraction difference of each alloying element by the total mass of the zinc liquid, resulting in the replenishment amounts for aluminum ingots, nickel blocks, and magnesium ingots.

[0056] The corresponding feeding devices are activated according to the amount of aluminum ingots, nickel blocks, and magnesium ingots added, and the materials are mixed by an electromagnetic stirring device to obtain zinc liquid with the required alloy element content.

[0057] Specifically, when detecting the current mass fractions of aluminum, nickel, and magnesium in molten zinc using a spark direct-reading spectrometer, the spectrometer is installed on the side wall of the zinc pot. The spectrometer probe is immersed 50 to 80 mm below the surface of the molten zinc. The spark direct-reading spectrometer uses vacuum ultraviolet spectroscopy analysis technology. When the probe comes into contact with the molten zinc, it generates a high-energy spark to excite the atoms in the molten zinc. When the excited atoms transition from a high energy level to a low energy level, they release spectral lines of specific wavelengths. The characteristic spectral line wavelength of aluminum is 396.152 nm, that of nickel is 341.476 nm, and that of magnesium is 285.213 nm. The photomultiplier tube inside the spectrometer receives these characteristic spectral lines and converts them into electrical signals. The intensity of the electrical signal is directly proportional to the mass fraction of the corresponding element. The spectrometer converts the electrical signal intensity into the element mass fraction according to a pre-established standard curve. After the detection is completed, the spectrometer outputs the current mass fractions of aluminum, nickel, and magnesium in the molten zinc. These three values ​​constitute the current composition data of the alloy elements in the molten zinc. When calculating the difference between the current mass fraction of each element in the current composition data of the zinc liquid alloy and its corresponding target mass fraction, the target mass fraction of aluminum is set to 0.020%, the target mass fraction of nickel is set to 0.10%, and the target mass fraction of magnesium is set to 0.04%. The difference is calculated by subtracting the current mass fraction from the target mass fraction. The mass fraction difference of aluminum is equal to the target mass fraction of aluminum (0.020%) minus the current mass fraction of aluminum; the mass fraction difference of nickel is equal to the target mass fraction of nickel (0.10%) minus the current mass fraction of nickel; and the mass fraction difference of magnesium is equal to the target mass fraction of magnesium (0.04%) minus the current mass fraction of magnesium. A positive difference indicates that the content of the element is lower than the target value and needs to be added; a negative difference indicates that the content of the element is higher than the target value and does not need to be added; and a difference of zero indicates that the content of the element is exactly equal to the target value and does not need to be added. When calculating the replenishment amount by multiplying the mass fraction difference of each alloying element by the total mass of the zinc liquid, the total mass of the zinc liquid is obtained in real time through weighing sensors. When calculating the replenishment amount of aluminum ingots, the mass fraction difference of aluminum is multiplied by the total mass of the zinc liquid and then multiplied by a conversion factor. The conversion factor is 1 because the mass fraction difference itself is in percentage form and needs to be multiplied by the total mass to obtain the absolute mass. When calculating the replenishment amount of nickel blocks, the mass fraction difference of nickel is multiplied by the total mass of the zinc liquid and then multiplied by a conversion factor. When calculating the replenishment amount of magnesium ingots, the mass fraction difference of magnesium is multiplied by the total mass of the zinc liquid and then multiplied by a conversion factor. The calculated replenishment amount is in kilograms, and the replenishment amount data is transmitted to the central control system to generate feeding instructions.When feeding aluminum ingots, nickel blocks, and magnesium ingots, the corresponding feeding devices are activated respectively. The aluminum ingot feeding device includes a hopper, a screw conveyor, and a feeding port. The aluminum ingots are pre-crushed into small pieces and stored in the hopper. The control system calculates the running time of the screw conveyor based on the aluminum ingot feeding amount. The screw conveyor speed is constant at 30 revolutions per minute, and the mass of aluminum ingots conveyed per revolution is approximately 0.5 kg. The running time is equal to the aluminum ingot feeding amount divided by the conveyor's conveying capacity per minute. After the screw conveyor transports the aluminum ingots from the hopper to the feeding port, the aluminum ingots fall into the zinc liquid. The working principle of the nickel block feeding device and the magnesium ingot feeding device is the same as that of the aluminum ingot feeding device. The three feeding devices are activated simultaneously to add aluminum ingots, nickel blocks, and magnesium ingots into the zinc liquid respectively. After feeding is completed, the zinc liquid is stirred by an electromagnetic stirring device. The mixing process involves installing multiple electromagnetic coils at the bottom of the zinc pot using an electromagnetic stirring device. When energized, these coils generate a rotating magnetic field, which acts on the conductive molten zinc, producing electromagnetic force that drives the zinc liquid to flow. The stirring frequency is set to 15-20 Hz, and the stirring time is set to 8-10 minutes. During stirring, the added aluminum ingots, nickel blocks, and magnesium ingots melt in the high-temperature molten zinc and are thoroughly mixed with it under the influence of electromagnetic force. After stirring, the aluminum, nickel, and magnesium elements in the molten zinc are evenly distributed. A spectrometer is used to re-detect the composition of the molten zinc to confirm that the mass fraction of each element reaches the target range. The mass fraction error for aluminum is controlled within ±0.008%, for nickel within ±0.010%, and for magnesium within ±0.005%.

[0058] Figure 2 This is a schematic diagram illustrating the control range of zinc liquid alloy element mass fraction in an embodiment of this application. (Refer to...) Figure 2 The schematic diagram of the zinc liquid alloy element mass fraction control range in this application embodiment shows the target mass fractions and allowable error ranges of three key alloying elements: aluminum, nickel, and magnesium. The target mass fraction of aluminum is 0.020%, with an upper limit of allowable error of 0.028% and a lower limit of allowable error of 0.012%; the target mass fraction of nickel is 0.100%, with an upper limit of allowable error of 0.110% and a lower limit of allowable error of 0.090%; and the target mass fraction of magnesium is 0.040%, with an upper limit of allowable error of 0.045% and a lower limit of allowable error of 0.035%. By setting this control range, the stability of the zinc liquid composition is ensured. Aluminum is used to suppress the excessive formation of iron-zinc compounds, nickel improves the crystal structure of the alloy layer, and magnesium enhances the fluidity of the zinc liquid. The synergistic effect of the three elements ensures the high quality of the coating and the stable output of high zinc content.

[0059] In one specific embodiment, the replenishment amount is calculated by multiplying the difference in mass fraction of each alloying element by the total mass of the zinc liquid, resulting in the replenishment amounts of aluminum ingots, nickel blocks, and magnesium ingots, including:

[0060] The amount of aluminum ingot to be added is calculated by multiplying the difference in the mass fraction of each alloying element by the total mass of the zinc liquid.

[0061] The amount of nickel to be added is calculated by multiplying the difference in the mass fraction of each alloying element by the total mass of the zinc liquid.

[0062] The magnesium ingot replenishment amount is calculated by multiplying the difference in the mass fraction of each alloying element by the total mass of the zinc liquid.

[0063] The replenishment amounts of aluminum ingots, nickel blocks, and magnesium ingots are summarized to form alloy element replenishment instruction data, thus obtaining the replenishment amounts of aluminum ingots, nickel blocks, and magnesium ingots.

[0064] Specifically, when calculating the difference in the mass fraction of aluminum among the differences in the mass fraction of each alloying element by multiplying it by the total mass of the zinc liquid, the difference in the mass fraction of aluminum is a percentage value obtained by subtracting the current mass fraction of aluminum from the target mass fraction of aluminum. The total mass of the zinc liquid is the mass of all the zinc liquid in the zinc pot, which is obtained in real time by a weighing sensor and is in tons. When calculating the amount of aluminum ingots to be added, the percentage form of the difference in the mass fraction of aluminum needs to be converted into a decimal form. The conversion method is to divide the percentage by 100, and then multiply the converted decimal by the total mass of the zinc liquid to obtain the mass of aluminum that needs to be added. Since what is being added is aluminum ingots rather than pure aluminum, the purity of aluminum in the aluminum ingots is usually 99% to 99.5% according to the industrial aluminum ingot standard. The actual amount of aluminum ingots to be added is equal to the mass of aluminum that needs to be added divided by the purity of the aluminum ingots. After the calculation is completed, the amount of aluminum ingots to be added is obtained in kilograms. When calculating the difference in nickel mass fraction among the differences in the mass fraction of each alloying element by multiplying it by the total mass of the zinc liquid, the difference in nickel mass fraction is a percentage value obtained by subtracting the current mass fraction of nickel from the target mass fraction of nickel. When calculating the amount of nickel to be added, it is also necessary to convert the percentage form of the difference in nickel mass fraction to decimal form. Multiplying the converted decimal by the total mass of the zinc liquid gives the mass of nickel that needs to be added. The purity of nickel in the nickel block is usually 99% to 99.8% according to the standard purity of industrial nickel blocks. The actual amount of nickel to be added is equal to the mass of nickel that needs to be added divided by the purity of the nickel block. After the calculation, the amount of nickel to be added is given in kilograms. When calculating the difference in the mass fraction of magnesium among the differences in the mass fraction of each alloying element by multiplying it by the total mass of the zinc liquid, the difference in the mass fraction of magnesium is a percentage value obtained by subtracting the current mass fraction of magnesium from the target mass fraction of magnesium. When calculating the amount of magnesium ingot to be added, the percentage form of the difference in the mass fraction of magnesium needs to be converted into a decimal form. The converted decimal is multiplied by the total mass of the zinc liquid to obtain the mass of magnesium that needs to be added. The purity of magnesium in the magnesium ingot is usually 99% to 99.9% according to the industrial magnesium ingot standard. The actual amount of magnesium ingot to be added is equal to the mass of magnesium that needs to be added divided by the purity of the magnesium ingot. After the calculation is completed, the unit of magnesium ingot to be added is kilograms.When the replenishment amounts of aluminum ingots, nickel blocks, and magnesium ingots are aggregated to form the alloy element replenishment instruction data, the central control system integrates the three replenishment values ​​along with the corresponding feeding device numbers, feeding sequence, and feeding time windows into a complete feeding instruction. The feeding instruction data includes: aluminum ingot feeding device number 01, aluminum ingot replenishment amount (calculated value in kilograms), feeding start time (current moment); nickel block feeding device number 02, nickel block replenishment amount (calculated value in kilograms), feeding start time (current moment); and magnesium ingot feeding device number 03, magnesium ingot replenishment amount (calculated value in kilograms), feeding start time (current moment). The three feeding devices start simultaneously to execute the feeding operation. After the alloy element replenishment instruction data is generated, it is transmitted to the control module of each feeding device. The control module calculates the operating parameters of the feeding device based on the replenishment amount in the instruction data, including screw conveyor running time, hopper opening angle, and feeding speed.

[0065] In one specific embodiment, step S4 includes:

[0066] Based on the pipe diameter and steel type as query conditions, a matching query is performed in the four-dimensional parameter database to obtain the corresponding zinc bath temperature setting value and zinc immersion time setting value.

[0067] The zinc liquid temperature is controlled by a combination of gas heating system and electric heating system according to the set value of zinc liquid temperature. The zinc liquid temperature data is collected by multi-point temperature measurement and the average temperature value is calculated for temperature compensation and adjustment to obtain zinc liquid with the standard temperature.

[0068] A steel pipe with a salt film on its surface is immersed in a zinc bath at the specified temperature. The immersion time is controlled by an intelligent crane system according to the set zinc immersion time value to obtain a zinc-treated steel pipe.

[0069] The galvanized steel pipe is subjected to an internal blowing process. Compressed air heated to a set temperature is blown into the inner wall of the steel pipe through an internal blowing head to blow out the excess zinc liquid from the inner wall, thus obtaining a galvanized steel pipe.

[0070] Specifically, the system uses pipe diameter and steel type as query criteria to perform a matching query in a four-dimensional parameter database. This database stores historical data on zinc application rates for different pipe diameters and steel types under various combinations of zinc bath temperature and immersion time. By inputting the pipe diameter and steel type identifier, the database system automatically retrieves the corresponding optimal process parameter combination to obtain the required zinc bath temperature and immersion time settings for that batch of steel pipes. For example, when processing Q235 steel pipes with a diameter of 80mm and a wall thickness of 6mm, the system retrieves a zinc bath temperature setting of 442℃ and an immersion time setting of 5.5 minutes from the database. However, when processing Q355 steel pipes with a diameter of 150mm and a wall thickness of 10mm, due to the longer zinc bath immersion time required for medium carbon steel and the higher heat input needed for larger diameter pipes, the system retrieves a zinc bath temperature setting of 452℃ and an immersion time setting of 8.2 minutes. This database-based parameter matching mechanism replaces the traditional method relying on manual analysis. The verification and judgment mode ensures that steel pipes of different specifications can obtain process parameters that are compatible with their material properties and geometric dimensions. Next, based on the set value of the zinc liquid temperature, the zinc liquid temperature is controlled by the gas heating system and the electric heating system in a coordinated manner. The gas heating system is responsible for providing most of the heat for rapid heating and maintaining the base temperature, while the electric heating system is used for fine adjustment and local temperature compensation. The control system collects zinc liquid temperature data by arranging multiple temperature sensors at different locations in the galvanizing pot through a multi-point temperature measurement method. Specifically, temperature monitoring points are set at the surface, middle and bottom layers of the zinc liquid, as well as the front, middle and rear of the galvanizing pot. After collecting the temperature values ​​of each point in real time, the average temperature value is calculated. When the temperature of a certain monitoring point deviates from the average value by more than a set threshold, the control system automatically adjusts the power of the electric heating unit corresponding to that area for temperature compensation adjustment. For example, when the set temperature is 442℃, if the front surface temperature sensor shows 438℃, the middle layer shows 442℃, and the rear bottom layer shows 445℃, the calculated average temperature is 441℃.At 67℃, the system determines that the temperature in the front-end area is too low and needs to be compensated for by increasing the temperature. It automatically increases the output power of the front-end electric heating unit while reducing the power of the rear-end heating unit. Through dynamic adjustment, the temperature at each monitoring point becomes more uniform, ultimately resulting in a zinc bath with the required temperature. This multi-point temperature measurement and zoned control temperature management strategy solves the problem of uneven zinc bath temperature distribution caused by traditional single-point temperature measurement. Subsequently, steel pipes covered with a salt film are immersed in the zinc bath at the required temperature. The immersion time is controlled by an intelligent crane system based on the set immersion time. The intelligent crane system is equipped with a precise time control module and a position feedback device. After the operator hoists the steel pipe onto the crane hook, they input the corresponding immersion time set value for that batch of steel pipes into the control panel, and the crane system is activated. The steel pipe is then automatically and slowly lowered vertically into the molten zinc, while a timer records the immersion time. Once the pipe is completely submerged, the timer continues running until the set immersion time is reached. During this time, the control system monitors the pipe's position and depth in the zinc solution to ensure it remains within the optimal temperature range. When the timer indicates the immersion time has reached the set value, the crane system automatically initiates a lifting procedure to uniformly raise the pipe from the zinc solution. The lifting speed is controlled within the range of 0.8-1.2 meters per minute to ensure sufficient zinc adhesion and avoid uneven coating due to excessive lifting speed. This results in a molten zinc-coated steel pipe, where both the surface and inner wall are covered with a layer of molten zinc. The molten steel pipe is then subjected to an internal blowing process. The internal blowing process is specifically designed for... The system cleans the inner wall of a tubular structure by blowing heated compressed air to a set temperature through an internal blower. The internal blower is an insertion-type air-blowing device with multiple radially distributed nozzles at its front end. As soon as the steel pipe is lifted from the molten zinc, the internal blower is inserted into one end. The compressed air, heated to 280-320°C by a heater, is then sprayed at a set pressure through the nozzles of the internal blower onto the inner wall of the steel pipe. The high-temperature, high-pressure airflow impacts the still-unsolidified molten zinc on the inner wall, causing it to flow and exit from the other end of the pipe. The internal blowing process lasts 15-25 seconds until the zinc layer thickness on the inner wall reaches a uniform state. For example, for a steel pipe with a diameter of 80mm, compressed air at a pressure of 0.6MPa and a temperature of 300°C is blown for 20 seconds. For steel pipes with a diameter of 150mm, compressed air at a pressure of 0.8MPa and a temperature of 320℃ is blown for 25 seconds. The final thickness of the zinc layer on the inner wall is controlled by adjusting the temperature, pressure, and blowing time of the compressed air. After internal blowing, a galvanized steel pipe is obtained. At this point, the zinc layer thickness on both the outer and inner walls of the steel pipe is uniform and meets the target zinc coating requirements. The entire process, from parameter querying to temperature control, immersion zinc treatment, and internal blowing cleaning, achieves precise control of high zinc coating. A four-dimensional parameter database ensures accurate matching of process parameters with steel pipe specifications. Multi-point temperature measurement and coordinated heating ensure the uniformity and stability of the zinc bath temperature. An intelligent crane system enables precise control of the immersion zinc time, and the internal blowing process optimizes the zinc layer distribution within the pipe.

[0071] The intelligent gantry system's correlation with the zinc immersion time is achieved through real-time communication between the gantry controller and the central control system. The central control system retrieves the set zinc immersion time from the four-dimensional parameter database and sends this time parameter to the gantry controller via industrial Ethernet. The gantry controller controls the variable frequency motor to drive the hook, lowering the steel pipe at a uniform speed into the zinc bath. When the steel pipe is fully submerged, the photoelectric liquid level sensor on the side wall of the zinc pot detects liquid level fluctuations and sends an immersion signal to the gantry controller. Upon receiving the immersion signal, the gantry controller immediately starts its built-in software timer, incrementing the count every millisecond. When the count reaches the preset zinc immersion time, the timer triggers an interrupt. Upon receiving the interrupt signal, the gantry controller immediately controls the motor to rotate in the opposite direction, driving the hook to rise and lift the steel pipe from the zinc bath. Real-time adjustment of the zinc immersion time is achieved through a temperature compensation mechanism. The gantry controller receives real-time feedback from the temperature control system regarding the actual temperature of the zinc bath. When the actual temperature deviates from the set temperature, the gantry controller calculates the time correction based on the built-in temperature-time correction curve. The correction curve was obtained by fitting a large amount of experimental data. When the zinc bath temperature is lower than the set temperature, the immersion time is extended to compensate for the decrease in reaction rate; when the temperature is higher than the set value, the immersion time is shortened to avoid over-reaction. The crane controller adds or subtracts the correction amount from the original immersion time set value to obtain the actual control time, thereby realizing the dynamic adjustment of the immersion time.

[0072] The adaptive control of the internal blowing head temperature is achieved through temperature sensor feedback and a PID control algorithm. A K-type thermocouple temperature sensor is installed on the air inlet pipe of the internal blowing head to monitor the temperature of the compressed air blown onto the inner wall of the steel pipe in real time. The temperature sensor transmits the temperature signal to the internal blowing controller, which uses a PID algorithm to adjust the heating power of the tubular electric heater based on the temperature deviation. The target temperature of the internal blowing head is adaptively set according to the steel pipe diameter and coating thickness. For small-diameter steel pipes, the zinc liquid adhesion on the inner wall is less and heat dissipation is faster, so the set temperature is lower, between 280℃ and 320℃. For large-diameter steel pipes, the zinc liquid adhesion on the inner wall is more and heat dissipation is slower, so the set temperature is higher, between 350℃ and 420℃. The internal blowing controller receives the current steel pipe diameter data from the central control system, automatically determines the target temperature based on a pre-stored pipe diameter-temperature correspondence table, and transmits it to the PID controller. During the internal blowing process, the temperature sensor collects the actual temperature every 100 milliseconds. The PID controller calculates the deviation between the actual temperature and the target temperature and adjusts the electric heater power based on the calculation results of the proportional, integral, and derivative operations. When the actual temperature is lower than the target temperature, the heating power is increased to rapidly raise the temperature. When the temperature approaches the target temperature, the heating power is reduced to prevent overshoot. Dynamic adjustment using a PID algorithm ensures that the compressed air temperature remains stable within the target temperature range, with fluctuations not exceeding ±5℃. After internal blowing is completed, the internal blowing controller sends a signal indicating that the internal blowing temperature has met the target and the actual blowing time data back to the central control system.

[0073] In one specific embodiment, step S5 includes:

[0074] The air cooling time parameters are determined based on the pipe diameter. The galvanized steel pipe is subjected to rotary air cooling treatment to reduce the surface temperature of the steel pipe to an intermediate temperature, thus obtaining an air-cooled steel pipe.

[0075] The air-cooled steel pipe is immersed in deionized water with benzotriazole corrosion inhibitor for water cooling treatment to reduce the temperature of the steel pipe to room temperature, thus obtaining a water-cooled steel pipe.

[0076] Metallographic analysis was performed on the coating of the steel pipe after water cooling treatment. Data on the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer in the coating were collected to obtain the microstructure parameters of the coating.

[0077] Based on the coating microstructure parameters, determine whether the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer are within the set range. If the determination is successful, output the result to obtain the finished galvanized steel pipe.

[0078] Specifically, after the galvanized steel pipe completes the internal blowing process, it needs to immediately enter the post-processing stage. First, the air cooling time parameters are determined based on the pipe diameter. Since steel pipes of different diameters have different heat capacities and heat dissipation area ratios, differentiated cooling times are required to control the cooling rate. Specifically, the air cooling time is set at 5-8 minutes for 50mm diameter pipes, 8-10 minutes for 80mm diameter pipes, 10-12 minutes for 120mm diameter pipes, and 12-15 minutes for pipes with diameters of 150mm and above. These time parameters are calculated based on the heat loss rate required for the steel pipe to cool from the galvanizing temperature to the intermediate temperature. The intermediate temperature refers to the temperature required for the steel pipe to cool from the galvanizing temperature to the intermediate temperature. When the pipe surface temperature drops to the range of 300-320℃, the zinc layer begins to solidify but still retains a certain degree of fluidity, which is beneficial for the uniform formation of the alloy layer during subsequent water cooling. After determining the air cooling time parameters, the galvanized steel pipe is subjected to rotary air cooling. Rotary air cooling is a process of cooling while rotating. The high-temperature steel pipe that has just completed internal blowing is placed on a rotating support, which drives the steel pipe to rotate continuously at a speed of 8-12 revolutions per minute. At the same time, multiple air outlets are arranged around the steel pipe to blow room temperature air onto the surface of the steel pipe. The rotational motion ensures that all parts of the steel pipe are evenly exposed to the cooling airflow, avoiding uneven coating thickness caused by excessive temperature difference between the upper and lower surfaces during static cooling. During the rotary cooling process, an infrared thermometer is used to monitor the temperature in real time. The surface temperature of the steel pipe is monitored. When the temperature gauge shows that the surface temperature of the steel pipe has dropped to the set intermediate temperature range, the rotation cooling is stopped, resulting in an air-cooled steel pipe. At this point, the zinc layer on the surface of the steel pipe has basically solidified, but the internal temperature remains relatively high. Next, the air-cooled steel pipe is immersed in deionized water with added benzotriazole corrosion inhibitor for water cooling treatment. Benzotriazole is an organic corrosion inhibitor that can form a protective film on the zinc layer surface during water cooling to prevent zinc from oxidizing with water. The conductivity of the deionized water is less than 10 microsiemens per centimeter, and it does not contain chloride and sulfate ions that can cause coating corrosion. The mass fraction of the added corrosion inhibitor is controlled at 0.8-1.2%, and the water temperature of the water cooling tank is maintained at 15-25℃. After the steel pipe is immersed in the water, the surface... The surface temperature drops rapidly. Upon contact with the high-temperature steel pipe, the cooling water absorbs heat and its temperature rises. A circulating cooling system continuously replenishes the cooling water in the tank to maintain a stable water temperature. The immersion time of the steel pipe in the water is controlled within the range of 3-8 minutes, depending on the pipe diameter. During this time, residual heat inside the steel pipe is gradually conducted to the surface through the pipe wall and carried away by the cooling water. When the core temperature of the steel pipe approaches the same as the surface temperature and the overall temperature drops to room temperature (20-30℃), the water cooling treatment is completed, resulting in a water-cooled steel pipe. At this point, the coating on the steel pipe has completely solidified and the internal temperature is uniform. Subsequently, metallographic analysis of the coating on the water-cooled steel pipe is performed. Metallographic analysis is a method of detecting the microstructure of the coating by preparing metallographic sections from steel pipe samples and observing them under a metallographic microscope.First, cut a circular sample with a length of about 10 mm on the steel pipe. After embedding the sample in resin and curing it, polish it successively with sandpaper until it reaches a mirror state. Then, corrode the surface of the sample with an etching agent to reveal the microstructure of the coating. Place the prepared sample on the stage of a metallurgical microscope and observe the microstructure morphology of the coating cross-section at a magnification of 200 - 500 times. Collect the data of the mass fraction of iron-zinc compounds and the thickness data of the iron-aluminum intermetallic compound inhibition layer in the coating. Iron-zinc compounds refer to the intermetallic compounds formed by iron and zinc elements in the coating, mainly including phase structures such as Gamma-Fe3Zn10, Delta-FeZn7, and Zeta-FeZn13. These compounds have high hardness but poor toughness. An excessive content will lead to an increase in the brittleness of the coating. Measure the area proportion of the distribution area of iron-zinc compounds in multiple fields of view through an energy dispersive spectrometer, and take the average value of the area proportion data of each field of view to obtain the mass fraction of iron-zinc compounds. The iron-aluminum intermetallic compound inhibition layer refers to the Fe2Al5 phase layer formed on the side close to the steel pipe substrate in the coating. This phase layer can block the diffusion of iron atoms in the substrate into the zinc liquid, thereby inhibiting the excessive formation of iron-zinc compounds. Measure the thickness of the Fe2Al5 phase layer on the coating cross-section through a metallurgical microscope. Select 8 measurement points at equal intervals in the circumferential direction of the sample, and use the scale function of the microscope to measure the vertical distance from the substrate surface to the pure zinc layer of the inhibition layer at each point. Take the arithmetic average of the thickness values of the 8 measurement points to obtain the average thickness data of the inhibition layer.汇总铁锌化合物质量分数和抑制层平均厚度两项数据形成镀层组织结构参数,根据镀层组织结构参数判断铁锌化合物质量分数和铁铝金属间化合物抑制层厚度是否在设定范围内,设定范围是基于大量试验数据确定的镀层质量合格判据,铁锌化合物质量分数的合格范围为5-8%,低于5%说明镀层中合金层发育不充分影响镀层与基体的结合强度,高于8%则表明脆性化合物含量过高会降低镀层韧性,铁铝金属间化合物抑制层厚度的合格范围为2-4微米,厚度过薄抑制效果不足导致铁锌化合物生成过多,厚度过厚则会降低镀层整体的结合力,检测人员将实测的铁锌化合物质量分数与5-8%范围比较,将实测的抑制层厚度与2-4微米范围比较,当两项参数同时落在各自设定范围内时判断通过,将该批次钢管标记为合格品输出,得到镀锌钢管成品,如果任一参数超出设定范围则判断不通过,需要对该批次钢管进行返工处理或调整工艺参数重新生产。,

[0079] The high zinc coating amount control method for hot-dip galvanized steel pipes in the embodiments of the present application is described above. Next, the high zinc coating amount control system for hot-dip galvanized steel pipes in the embodiments of the present application will be described. Please refer to Figure 3 It should be noted that there seems to be some text repetition and an incomplete sentence in the original Chinese text. The translation is done as accurately as possible based on the provided content.One embodiment of the high zinc coating control system for hot-dip galvanized steel pipes in this application includes:

[0080] The processing module is used to sequentially perform a first pickling with hydrochloric acid with a mass fraction between 18% and 22%, a first water wash with flowing water, a second pickling with hydrochloric acid with a mass fraction between 8% and 12% and surfactant, and a second water wash with deionized water to obtain a pretreated steel pipe substrate.

[0081] The immersion module is used to immerse the pretreated steel pipe substrate in a zinc chloride-ammonium chloride solvent that has undergone ion exchange iron removal and pressure filtration separation, and then immerse it in a composite flux containing potassium fluoroborate and nickel nitrate and dry it in a drying oven to obtain a steel pipe with a salt film covering its surface.

[0082] The stirring module is used to monitor the mass fractions of aluminum, nickel, and magnesium in the zinc bath in real time using a spectrometer. Based on the difference between the target mass fraction and the current mass fraction, as well as the total mass of the zinc bath, the amount of each alloying element to be added is determined and stirred to obtain a zinc bath with the alloying element content meeting the standard.

[0083] The internal blowing module is used to query the corresponding zinc bath temperature and immersion time from a preset four-dimensional parameter database according to the steel pipe diameter and steel type, immerse the steel pipe with the salt film covering the surface into the zinc bath with the alloy element content meeting the standard, and combine it with the internal blowing process to obtain the galvanized steel pipe.

[0084] The control module is used to sequentially perform rotary air cooling to an intermediate temperature and deionized water cooling with added corrosion inhibitor to room temperature on the galvanized steel pipe. The air cooling time is adjusted according to the pipe diameter to control the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer, so as to obtain the finished galvanized steel pipe.

[0085] Specifically, the processing module includes a primary pickling unit, a primary water washing unit, a secondary pickling unit, and a secondary water washing unit. The primary pickling unit is a rectangular pickling tank filled with a hydrochloric acid solution with a mass fraction of 18% to 22%. An electric heating element at the bottom of the tank heats the solution to 45°C to 50°C, and a temperature sensor connected to a temperature controller automatically adjusts the heating power. The crane system retrieves preset immersion time parameters from the control system based on the steel type. For Q235 steel, the immersion time is set to 60 to 65 seconds. After the timer expires, the steel pipe is automatically lifted and transferred to the primary water washing unit. The primary water washing unit includes a spray zone and an immersion zone. Multiple rows of spray pipes are installed at the top of the spray zone, with water pressure controlled at 0.2 to 0.3 MPa, spraying for 10 to 15 minutes to rinse the surface acid solution. The soaking area is a flowing clean water tank. After the crane immerses the steel pipe, it executes the stirring procedure. The crane controls the up and down lifting of the hook and the horizontal swing to ensure that the steel pipe is in full contact with the clean water. After soaking and stirring for 8 to 12 minutes, the steel pipe is lifted and tilted at 30 to 45 degrees for 15 to 20 seconds to complete the tilting and water control.

[0086] The secondary pickling tank contains a hydrochloric acid solution with a mass fraction of 8% to 12%. A corrosion inhibitor of hexamethylenetetramine (0.2% to 0.4% by mass) and a surfactant of sodium dodecylbenzenesulfonate (0.1% to 0.2% by mass) are added to the solution. The corrosion inhibitor adsorbs onto the steel pipe surface to form a protective film, slowing down corrosion, while the surfactant reduces surface tension, allowing the acid to penetrate into even the smallest defects. The temperature is controlled at 35°C to 40°C, and immersion for 6 to 8 minutes achieves a fine-tuning process.

[0087] The secondary washing unit first soaks the pipe in running clean water for 18 to 22 minutes with agitation and tilting to control the water flow, followed by deionized water spraying. The deionized water is prepared by an ion exchange device, with a conductivity below 10 microsiemens per centimeter. The spraying pressure is 0.25 to 0.35 MPa, and the spraying time is 8 to 12 minutes. Ultimately, the pH value of the steel pipe surface is controlled between 6.5 and 7, and the conductivity of the surface water film is reduced to below 30 microsiemens per centimeter, ensuring no residue. The treatment module coordinates the actions of each unit through a central control system. A level sensor automatically replenishes the liquid when the level falls below the lower limit, and a concentration monitor prompts for replacement when the acid concentration deviates from the limit.

[0088] The immersion module includes a solvent treatment system, a composite fluxing system, and a drying system. The solvent tank contains a mixed solvent of 110 to 140 g / L zinc chloride and 220 to 240 g / L ammonium chloride, and the temperature is maintained at 50°C to 55°C. The solvent is circulated through an ion exchange iron removal unit, an oxidation reaction tank, and a plate and frame filter press before being returned.

[0089] The ion exchange iron removal device consists of an exchange column filled with strongly acidic cation exchange resin. As the solvent flows through the resin bed, ferrous ions exchange with hydrogen ions on the resin, and the ferrous ions are captured by the resin. Compressed air is introduced into the bottom of the oxidation reaction tank; oxygen oxidizes the remaining ferrous ions to ferric ions, forming ferric hydroxide precipitate. Aeration and stirring are performed for 15 to 20 minutes. A plate and frame filter press uses 200 to 400 mesh polypropylene filter cloth, with a filtration accuracy of 5 to 10 microns, completely retaining precipitates and suspended oxides under a pressure of 0.3 to 0.5 MPa. After purification, the ferric ion content in the solvent is reduced to below 0.3%, and the oxide content is reduced to below 0.1%.

[0090] The steel pipe is immersed in the purified solvent for 10 to 15 minutes, then lifted and drained for 2 to 3 minutes before being immersed in a composite flux solution. The flux is formulated with 20% to 22% zinc chloride, 5% to 7% ammonium chloride, 0.3% to 0.5% potassium fluoroborate, and 0.2% to 0.4% nickel nitrate. The flux tank is equipped with an intelligent temperature control system, using a PID controller to adjust the power of the heating element based on real-time signals from the temperature sensor, precisely maintaining the temperature between 55℃ and 60℃, with fluctuations within ±0.5℃. An online concentration monitor measures conductivity and performs temperature compensation to calculate the concentration. When the zinc chloride concentration is below 20% or the ammonium chloride concentration is below 5%, the replenishment pump is automatically activated. The pump running time is calculated based on the concentration difference and the tank volume. After replenishment, the tank is stirred for 5 minutes to ensure uniform concentration.

[0091] After immersing the steel pipe in the flux for 8 to 12 minutes, lift it out and drain for 1 to 2 minutes before placing it in a drying kiln. The drying kiln uses hot air circulation heating, with the temperature controlled at 60℃, and drying takes 15 to 20 minutes. During the drying process, the moisture in the liquid film on the surface of the steel pipe evaporates, and the dissolved salts crystallize and precipitate to form a uniform salt film with a thickness of 8 to 12 micrometers. After drying, the thickness is measured at 8 points on the outer wall of the steel pipe using a coating thickness gauge. The average thickness is required to be 8 to 12 micrometers, with a deviation of no more than ±15% at each point. The salt film coverage is visually inspected, requiring 100% coverage without defects such as missed coatings, peeling, or cracks.

[0092] The stirring module includes a spark direct-reading spectrometer, a central control system PLC, three sets of feeding devices, and an electromagnetic stirring device. The spectrometer is fixed to the side wall of the zinc pot, with the probe immersed 50 to 80 mm below the surface of the molten zinc. It automatically detects the mass fraction of aluminum, nickel, and magnesium every 30 minutes. The PLC uses a Siemens S7-1200 series, communicating with the spectrometer via an RS485 interface and with the feeding devices via Ethernet. After the spectrometer completes its detection, it transmits the current mass fractions of aluminum, nickel, and magnesium to the PLC via the RS485 interface using the Modbus protocol. The PLC calculates the difference between the current mass fraction and the preset target mass fractions (0.020% aluminum, 0.100% nickel, and 0.040% magnesium). The PLC reads the total mass of the molten zinc from the weighing sensor, multiplies the mass fraction difference by the total mass of the molten zinc, and divides by the corresponding material purity coefficient to calculate the replenishment amount of aluminum ingots, nickel blocks, and magnesium ingots. The PLC packages information such as replenishment amount, device address, and feeding time into instruction data and sends it simultaneously to the local controllers of the three feeding devices via Ethernet.

[0093] Each feeding device includes a storage hopper, a screw conveyor, a drive motor, a frequency converter, a local controller, a mass flow meter, and a feeding port. The storage hopper is conical with a volume of approximately 1.5 cubic meters. Its bottom is connected to the screw conveyor's inlet via a flange, and the outlet is equipped with a pneumatic-electric gate valve. The screw conveyor is a tubular structure with an inner diameter of 300 mm and a length of 6 meters. The screw blades have an outer diameter of 294 mm and a pitch of 300 mm. The drive motor has a power of 7.5 kW, reduced to 30 rpm by a reducer, and its start and stop are controlled by the frequency converter. The local controller is a Siemens S7-200 SMART small PLC. The feeding port is a 45-degree inclined guide pipe, with its lower end 20 to 30 cm below the zinc molten liquid surface, allowing material to fall freely into the zinc molten liquid. After receiving the feeding command from the central PLC, the local controller analyzes and calculates the replenishment amount for this device. It is known that the screw conveyor conveys 0.5 kg per revolution at 30 rpm, and its conveying capacity is 15 kg per minute. The local controller calculates the running time as: replenishment amount ÷ 15 kg / minute. For example, with a replenishment amount of 2.5 kg, the running time is 2.5 ÷ 15 = 0.167 minutes = 10 seconds. The local controller sets the timer preset to 10 seconds and sends a start signal to the frequency converter. The frequency converter drives the motor to rotate, causing the screw shaft to rotate. The material in the hopper is pushed by the screw blades to the discharge end and falls into the zinc liquid through the feeding port. When the timer reaches 10 seconds, the local controller disconnects the frequency converter's start signal to stop the machine and simultaneously sends a signal to close the electric gate valve to cut off the material. All three sets of devices receive the command simultaneously and execute independently, achieving synchronized feeding.

[0094] A mass flow meter above the feed inlet monitors the cumulative feed amount in real time. The local controller reads this value and reduces the speed to 5 revolutions per minute when the cumulative amount reaches 98% of the target replenishment amount. It stops the machine when it reaches 100% to improve feed accuracy. The local controller records the target amount and the actual amount of feed each time. When the relative error exceeds ±3% for 5 consecutive times, a calibration program is automatically triggered to remeasure and update the conveying capacity parameters, compensating for deviations caused by changes in material density or equipment wear.

[0095] The electromagnetic stirring device consists of six sets of electromagnetic coils evenly arranged at the bottom of the zinc pot, a three-phase AC power supply, and a frequency controller. The coils are multi-turn copper wire wound and encapsulated within a high-temperature resistant insulating frame. The six sets of coils are connected to the three-phase power supply with a 60-degree phase difference to form a rotating magnetic field. The frequency controller has an adjustable output frequency of 10 to 30 Hz. After feeding is completed, the local controller sends a feeding completion signal to the central PLC. Upon receiving the completion signals from the three sets of devices, the central PLC sends a start command to the frequency controller and sets the frequency to 15 to 20 Hz and the time to 8 to 10 minutes. The rotating magnetic field generates an electromagnetic force on the conductive zinc liquid, driving eddy currents to achieve circulating flow. The device automatically stops after the stirring time is reached, and a spectrometer re-detects and verifies that the mass fraction errors of each element are within the allowable range (aluminum ±0.008%, nickel ±0.010%, magnesium ±0.005%).

[0096] The internal blowing module includes a four-dimensional parameter database, a temperature control system, an intelligent crane system, and an internal blowing device. The four-dimensional parameter database is an SQL relational database that stores zinc bath temperature and immersion time parameters corresponding to different pipe diameters and steel grades. The database table structure includes fields for steel grade type, pipe diameter range, zinc bath temperature, and immersion time. Operators input the pipe diameter and steel grade information through a human-machine interface. The central control system executes SQL queries to retrieve matching temperature and time setpoints from the database. For example, for an 80mm diameter Q235 steel pipe, the query yields a temperature of 442℃ and a time of 5.5 minutes.

[0097] The temperature control system includes a gas heating system, an electric heating system, and a multi-point temperature measurement system. A gas burner at the bottom of the zinc pot provides the main heat for rapid heating, while electric heating rods on the side walls allow for fine adjustment and local compensation. Five platinum-rhodium thermocouple temperature sensors are evenly distributed inside the zinc pot, located at the surface, middle, and bottom layers, as well as the front, middle, and rear ends. The sensors transmit temperature signals to the temperature controller, which calculates the arithmetic mean of the five measurement points as the actual temperature. When the average temperature deviates from the set temperature by more than ±2℃, the controller calculates the power compensation for each area's electric heating rod based on the deviation of each measurement point from the average value. The controller then adjusts the power of each heating rod via a silicon controlled rectifier (SCR) voltage regulator to ensure uniform temperature distribution. After dynamic adjustment, the temperature fluctuation at each point in the zinc liquid is controlled within ±3℃.

[0098] The intelligent crane system consists of a crane mechanical structure, a variable frequency drive motor, and a crane controller. The crane controller receives the zinc immersion time setpoint from the central control system and controls the crane to lift and move the steel pipe, covered with a salt film, above the zinc pot. The pipe is then lowered at a constant speed of 10 to 15 centimeters per second to immerse it in the molten zinc. The photoelectric sensor detects a signal the instant the pipe is fully submerged, and the crane controller starts a timer. During the timer, the crane maintains a constant immersion depth to prevent up-and-down movement. When the timer reaches the set 5.5 minutes, it triggers a lifting signal, and the crane lifts the pipe out of the molten zinc at a constant speed of 15 to 20 centimeters per second. This moderate lifting speed ensures adequate zinc adhesion and a uniform coating.

[0099] The internal blowing device includes an internal blowing head, a compressed air supply system, a heater, and a linear motion mechanism. The internal blowing head is a cylindrical structure with an outer diameter slightly smaller than the inner diameter of the steel pipe, and has 8 to 12 radial nozzles distributed at its front end. Compressed air is delivered through a pipeline to a tubular electric heater, which heats the air to 370°C to 450°C. The heated, high-temperature compressed air then enters the internal blowing head and is ejected from the nozzles. Immediately after the steel pipe is lifted from the molten zinc, the linear motion mechanism inserts the internal blowing head into one end of the pipe. The linear motion mechanism drives the internal blowing head to move uniformly along the axial direction of the steel pipe at a speed of 20 to 30 centimeters per second. The high-temperature, high-pressure airflow impacts the inner wall of the steel pipe, blowing away any excess molten zinc that has not yet solidified towards the pipe opening. The compressed air pressure is controlled at 0.4 to 0.6 MPa, and the blowing time is set according to the pipe diameter; for an 80 mm diameter steel pipe, the blowing time is 20 seconds. After internal blowing is completed, the linear motion mechanism withdraws the internal blowing head, resulting in a uniform zinc layer thickness on the inner wall of the steel pipe without any accumulation.

[0100] The control module includes a rotary air cooling device, a water cooling system, and a metallographic structure detection device. The rotary air cooling device consists of a rotating support, a drive motor, and an air supply system. The rotating support is a V-shaped bracket on which the steel pipe is placed, and the bracket is connected to the rotating shaft driven by the motor. The motor speed is adjustable, and the cooling time parameters are determined according to the diameter of the steel pipe; for a pipe diameter of 80 mm, the cooling time is set to 8 minutes. After the motor starts, it drives the steel pipe to rotate slowly at a speed of 5 to 8 revolutions per minute. The air supply system arranges multiple axial flow fans around the steel pipe, blowing room temperature air onto the surface of the steel pipe at a speed controlled at 3 to 5 meters per second. An infrared thermometer non-contactly monitors the surface temperature of the steel pipe, and the temperature data is fed back to the controller in real time. When the surface temperature drops to an intermediate temperature of 300℃ to 320℃, the controller stops the motor rotation, completing the air cooling stage. During the cooling process, aluminum in the zinc liquid diffuses and reacts with iron on the surface of the steel pipe to form an iron-aluminum intermetallic compound inhibition layer. The inhibition layer, located between the substrate and the pure zinc layer, prevents iron atoms in the substrate from diffusing further into the zinc layer, thereby inhibiting the excessive formation of brittle iron-zinc compounds. The cooling rate directly affects the thickness and uniformity of the inhibition layer; excessively rapid cooling results in insufficient layer development, while excessively slow cooling prolongs the production cycle. By adjusting the cooling time according to the pipe diameter—smaller diameters with lower heat capacity require shorter cooling times, while larger diameters with higher heat capacity require longer cooling times—precise control of the alloy layer structure is achieved. The water cooling system consists of a rectangular water tank filled with deionized water containing 0.8% to 1.2% benzotriazole corrosion inhibitor by mass. Benzotriazole adsorbs on the zinc layer surface to form a protective film, preventing zinc from reacting with water and oxidizing. The deionized water temperature is maintained between 15°C and 25°C, and a circulating cooling device continuously replenishes the cooling water in the tank to maintain a stable temperature. An overhead crane lifts the air-cooled steel pipe and immerses it in the water; the water cooling time for 80mm diameter steel pipes is 3 to 4 minutes. During the water cooling stage, the surface temperature of the steel pipe drops rapidly, and the zinc layer completely solidifies. After water cooling is completed, the steel pipe is lifted out. The overall temperature of the steel pipe drops to 20 to 30°C of room temperature, and the temperature difference between the inside and outside is less than 5°C.

[0101] The metallographic structure testing apparatus includes a sampling device, a sample preparation device, and a metallographic microscope. The sampling device cuts a 10 mm long annular sample from a steel tube. The sample preparation device embeds the sample in epoxy resin and cures it, then grinds it sequentially using sandpaper of different grits up to 2000 grit, and finally polishes it to a mirror finish with polishing compound. The sample surface is etched with a 4% (w / w) nitric acid-alcohol solution for 15 to 20 seconds to reveal the coating structure. The metallographic microscope is an inverted optical microscope equipped with a CCD digital camera and image analysis software. The prepared sample is placed on the microscope stage, and the cross-section of the coating is observed at 200 to 500x magnification.

[0102] Operators collected data on the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer in the coating. The iron-zinc compounds include Gamma, Delta, and Zeta phases, appearing as a gray, layered structure under a microscope. Operators used image analysis software to determine the proportion of the iron-zinc compound area to the total coating area across multiple fields of view, and the mass fraction was obtained by averaging the data from multiple fields. The iron-aluminum inhibition layer, consisting of the Fe2Al5 phase, is a light gray band located between the substrate and the pure zinc layer. Operators selected eight equally spaced measurement points along the circumference of the sample and used the microscope's scale function to measure the vertical thickness of the inhibition layer at each point. The arithmetic mean of the eight data points was used to obtain the average thickness of the inhibition layer.

[0103] Operators input the iron-zinc compound mass fraction and the inhibition layer thickness data into the quality assessment system. The system compares the measured mass fraction with a set range of 5% to 8%, and the measured thickness with a set range of 2 to 4 micrometers. When both parameters fall within their respective set ranges, the system determines that the batch of steel pipes is qualified and marks it as finished product output. If either parameter exceeds the range, the system determines that it is unqualified, and the steel pipes are returned for adjustment of process parameters and re-production. Through quantitative metallographic analysis, precise control of the coating's microstructure is achieved, ensuring a moderate content of iron-zinc brittle compounds and a uniform distribution of the iron-aluminum inhibition layer, significantly improving the coating's toughness and impact resistance.

[0104] above Figure 3 The high zinc coating control system for hot-dip galvanized steel pipes in this embodiment of the invention is described in detail from the perspective of modular functional entities. The high zinc coating control device for hot-dip galvanized steel pipes in this embodiment of the invention is described in detail from the perspective of hardware processing.

[0105] Reference Figure 4 This invention also provides a high zinc coating amount control device for hot-dip galvanized steel pipes. This device can be a server, and its internal structure can be as follows: Figure 4As shown, the high zinc coating amount control device for hot-dip galvanized steel pipes includes a processor, memory, display screen, input device, network interface, and database connected via a system bus. The processor, designed as a computer, provides computing and control capabilities. The memory of the high zinc coating amount control device includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database of the high zinc coating amount control device is used to store the data corresponding to this embodiment. The network interface of the high zinc coating amount control device is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements the above-described method.

[0106] Those skilled in the art will understand that Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the hot-dip galvanized steel pipe high zinc content control device to which the present invention is applied.

[0107] The present invention also provides a computer-readable storage medium, which can be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium, wherein the computer-readable storage medium stores instructions that, when the instructions are executed on a computer, cause the computer to perform the steps of the method for controlling the high zinc content of hot-dip galvanized steel pipes.

[0108] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0109] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present 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 hot-dip galvanized steel pipe high zinc content control device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present 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.

[0110] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the zinc coating amount of hot-dip galvanized steel pipes, characterized in that, The method includes: Step S1: The steel pipe is subjected to a first pickling with hydrochloric acid with a mass fraction between 18% and 22%, a first water wash with running water, a second pickling with hydrochloric acid with a mass fraction between 8% and 12% and surfactant, and a second water wash with deionized water to obtain the pretreated steel pipe substrate. Step S2: Immerse the pretreated steel pipe substrate in a zinc chloride-ammonium chloride solvent that has undergone ion exchange iron removal and pressure filtration separation, then immerse it in a composite flux containing potassium fluoroborate and nickel nitrate and dry it in a drying oven to obtain a steel pipe with a salt film covering its surface. Step S3: Monitor the mass fractions of aluminum, nickel, and magnesium in the zinc bath in real time using a spectrometer. Determine the amount of each alloying element to be added based on the difference between the target mass fraction and the current mass fraction, as well as the total mass of the zinc bath. Add the materials and stir to obtain a zinc bath with alloying element content that meets the standards. Step S4: Based on the pipe diameter and steel grade, query the corresponding zinc bath temperature and immersion time from the preset four-dimensional parameter database, immerse the steel pipe with the salt film covering the surface into the zinc bath with the alloy element content meeting the standard, and combine with the internal blowing process to obtain the galvanized steel pipe. Step S5: The galvanized steel pipe is sequentially subjected to rotary air cooling to an intermediate temperature and then to deionized water with added corrosion inhibitor to room temperature. The air cooling time is adjusted according to the pipe diameter to control the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer, thus obtaining the finished galvanized steel pipe.

2. The method for controlling the zinc coating amount of hot-dip galvanized steel pipes according to claim 1, characterized in that, Step S1 includes: Select the corresponding primary pickling process parameters according to the steel type of the steel pipe, immerse the steel pipe in a prepared hydrochloric acid solution with a mass fraction between 18% and 22% for primary pickling treatment, and obtain steel pipe with surface oxide scale and rust removed. The steel pipe with the surface oxide scale and rust removed is first sprayed with running water and then soaked in running water. During the soaking process, the steel pipe is moved up and down by an overhead crane, agitated back and forth in the water, and the steel pipe is tilted to drain the water, resulting in a steel pipe after one water washing. The steel pipe after the first water washing is immersed in a hydrochloric acid solution containing hexamethylenetetramine corrosion inhibitor and sodium dodecylbenzenesulfonate surfactant at a mass fraction of 8% to 12% for a second pickling treatment to obtain a steel pipe with residual oxide spots and stubborn rust removed. The steel pipe with residual oxide spots and stubborn rust removed is first soaked in flowing water and then sprayed with deionized water. During the soaking process, the steel pipe is moved up and down by an overhead crane, agitated back and forth in the water, and the steel pipe is tilted to control the water, so as to obtain the pretreated steel pipe substrate.

3. The method for controlling the zinc coating amount of hot-dip galvanized steel pipes according to claim 1, characterized in that, Step S2 includes: The pretreated steel pipe substrate is immersed in zinc chloride-ammonium chloride solvent, and the ferrous ions in the solvent are removed by an ion exchange iron removal device. Then, the residual ferrous ions are oxidized to ferric ions by passing compressed air into the solvent. Subsequently, the ferric hydroxide precipitate and suspended oxides are separated by a plate and frame filter press to obtain the purified steel pipe substrate. The purified steel pipe substrate is immersed in a composite flux solution containing zinc chloride, ammonium chloride, potassium fluoroborate and nickel nitrate. The temperature of the flux solution is maintained by an intelligent temperature control system and the concentrations of zinc chloride and ammonium chloride are monitored in real time by an online concentration monitor to trigger automatic replenishment, thus obtaining a steel pipe after being immersed in the flux. After the steel pipe is soaked in the flux, it is taken out and drained, and then sent to a drying kiln for drying treatment, so that a uniform and dense flux salt film layer is formed on the surface of the steel pipe, and a steel pipe with a surface covered by a flux salt film layer is obtained. The steel pipe with the salt coating layer on its surface is tested for salt film thickness and coverage. After confirming that the salt film thickness is within the set range and the coverage meets the standard, the steel pipe with the salt coating layer on its surface is output.

4. The method for controlling the zinc coating amount of hot-dip galvanized steel pipes according to claim 1, characterized in that, Step S3 includes: The current mass fractions of aluminum, nickel, and magnesium in the zinc melt were detected by spark direct-reading spectrometer to obtain the current composition data of the zinc melt alloy elements. The difference between the current mass fraction of each element in the current composition data of the zinc liquid alloy elements and the corresponding target mass fraction is calculated to obtain the mass fraction difference of each alloy element. The replenishment amounts for aluminum ingots, nickel blocks, and magnesium ingots are calculated by multiplying the mass fraction differences of each alloying element by the total mass of the zinc liquid. According to the amount of aluminum ingots, nickel blocks, and magnesium ingots added, the corresponding feeding devices are activated to feed the materials, and the materials are mixed by an electromagnetic stirring device to obtain zinc liquid with the alloy element content meeting the standard.

5. The method for controlling the high zinc coating amount of hot-dip galvanized steel pipes according to claim 4, characterized in that, The method of calculating the replenishment amount by multiplying the mass fraction difference of each alloying element by the total mass of zinc liquid to obtain the replenishment amount of aluminum ingots, nickel blocks, and magnesium ingots includes: The amount of aluminum ingot to be added is calculated by multiplying the difference in the mass fraction of each alloying element by the total mass of the zinc liquid. The amount of nickel block to be added is calculated by multiplying the difference in the mass fraction of each alloying element by the total mass of the zinc liquid. The magnesium ingot replenishment amount is calculated by multiplying the difference in the mass fraction of each alloying element by the total mass of the zinc liquid. The amounts of aluminum ingot replenishment, nickel block replenishment, and magnesium ingot replenishment are summarized to form alloy element replenishment instruction data, thus obtaining the amounts of aluminum ingot replenishment, nickel block replenishment, and magnesium ingot replenishment.

6. The method for controlling the zinc coating amount of hot-dip galvanized steel pipes according to claim 1, characterized in that, Step S4 includes: Based on the pipe diameter and steel type as query conditions, a matching query is performed in the four-dimensional parameter database to obtain the corresponding zinc bath temperature setting value and zinc immersion time setting value. Based on the set zinc liquid temperature, the zinc liquid temperature is controlled by a gas heating system and an electric heating system in coordination. The zinc liquid temperature data is collected by multi-point temperature measurement and the average temperature value is calculated for temperature compensation and adjustment to obtain zinc liquid with the specified temperature. The steel pipe with a salt film on its surface is immersed in the zinc bath at the specified temperature. The immersion time is controlled by an intelligent crane system according to the set zinc immersion time value to obtain a zinc-treated steel pipe. The galvanized steel pipe is subjected to an internal blowing process, in which compressed air heated to a set temperature is blown into the inner wall of the steel pipe through an internal blowing head to blow out excess zinc liquid from the inner wall, thus obtaining the galvanized steel pipe.

7. The method for controlling the zinc coating amount of hot-dip galvanized steel pipes according to claim 1, characterized in that, Step S5 includes: The air cooling time parameters are determined according to the diameter of the steel pipe. The galvanized steel pipe is subjected to rotary air cooling treatment to reduce the surface temperature of the steel pipe to an intermediate temperature, thus obtaining an air-cooled steel pipe. The air-cooled steel pipe is immersed in deionized water with benzotriazole corrosion inhibitor for water cooling treatment to reduce the temperature of the steel pipe to room temperature, thus obtaining a water-cooled steel pipe. Metallographic analysis was performed on the coating of the steel pipe after water cooling treatment. Data on the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer in the coating were collected to obtain the coating microstructure parameters. Based on the coating microstructure parameters, determine whether the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer are within the set range. If the determination is successful, output the result to obtain the finished galvanized steel pipe.

8. A high zinc coating control system for hot-dip galvanized steel pipes, characterized in that, For implementing the method for controlling the high zinc coating amount of hot-dip galvanized steel pipes as described in any one of claims 1-7, the control system for the high zinc coating amount of hot-dip galvanized steel pipes includes: The processing module is used to sequentially perform a first pickling with hydrochloric acid with a mass fraction between 18% and 22%, a first water wash with flowing water, a second pickling with hydrochloric acid with a mass fraction between 8% and 12% and surfactant, and a second water wash with deionized water to obtain a pretreated steel pipe substrate. The immersion module is used to immerse the pretreated steel pipe substrate in a zinc chloride-ammonium chloride solvent that has undergone ion exchange iron removal and pressure filtration separation, and then immerse it in a composite flux containing potassium fluoroborate and nickel nitrate and dry it in a drying oven to obtain a steel pipe with a salt film covering its surface. The stirring module is used to monitor the mass fractions of aluminum, nickel, and magnesium in the zinc bath in real time using a spectrometer. Based on the difference between the target mass fraction and the current mass fraction, as well as the total mass of the zinc bath, the amount of each alloying element to be added is determined and stirred to obtain a zinc bath with the alloying element content meeting the standard. The internal blowing module is used to query the corresponding zinc bath temperature and immersion time from a preset four-dimensional parameter database according to the steel pipe diameter and steel type, immerse the steel pipe with the salt film covering the surface into the zinc bath with the alloy element content meeting the standard, and combine it with the internal blowing process to obtain the galvanized steel pipe. The control module is used to sequentially perform rotary air cooling to an intermediate temperature and deionized water cooling with added corrosion inhibitor to room temperature on the galvanized steel pipe. The air cooling time is adjusted according to the pipe diameter to control the mass fraction of iron-zinc compounds and the thickness of the iron-aluminum intermetallic compound inhibition layer, so as to obtain the finished galvanized steel pipe.

9. A high zinc coating amount control device for hot-dip galvanized steel pipes, characterized in that, The method includes a memory and a processor, the memory storing a computer program that can run on the processor, and the processor executing the computer program to implement the method for controlling the high zinc coating amount of hot-dip galvanized steel pipes according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is run by the processor, it causes the processor to execute the method for controlling the high zinc coating amount of hot-dip galvanized steel pipes as described in any one of claims 1 to 7.

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