Galvanizing, also known as hot-dip galvanizing and hot-dip galvanizing, is an effective metal corrosion protection method, which is mainly used for metal structure facilities in various industries. The rust-removed steel parts are immersed in molten zinc at about 500℃, so that the zinc layer adheres to the surface of steel members, thus achieving the purpose of corrosion protection. Hot dip galvanizing process: finished product pickling-cleaning-adding plating solution-drying-hanging plating-cooling-dosing-cleaning-polishing-hot dip galvanizing is completed 1. Hot dip galvanizing is developed from an ancient hot dip galvanizing method. Since 1836 was applied to industry in France, it has a history of 170 years. In recent thirty years, with the rapid development of cold-rolled strip steel, the hot-dip galvanizing industry has developed on a large scale. \x0d\x0d\ Hot dip galvanizing (steel pipe) production process: \ x0d \ Feeding → Pickling and washing → Solvent → Drying → Hot dip galvanizing → Internal and external blowing → Labeling and marking → Passivation → Inspection → Packaging. \x0d\ x0d \ Loading \ x0d \ Loading workers should check the raw materials: \x0d\ 1. Oil stain (especially asphalt oil ready mixed paint) shall not be attached to the outer surface of steel pipe, otherwise a large number of unqualified products will be caused. \x0d\ 2。 Steel pipes must be straightened after production to eliminate the internal stress of steel pipes. \x0d\ 3。 The uneven corrosion of the outer surface of steel pipe cannot be galvanized, otherwise a lot of hydrochloric acid will be wasted. \x0d\ 4。 Steel pipes should not be artificially bent during transportation. \x0d\ 5。 For steel pipes used for hot dip galvanizing, it is not allowed to stick marks on the inner and outer walls of steel pipes to avoid missing plating. \ x0d \ x0d \ acid washing, water washing \x0d\ 1. Pickering of steel pipes: \x0d\ 1) Pickers must wear labor protection articles before work, and carefully check whether the workplace is barrier-free and whether the slings are in good condition before work. \x0d\ 2) Pickling mainly adopts hydrochloric acid pickling, which is prepared with water, and the hydrochloric acid content is 18 ~ 20%. \x0d\ 3) Before working, the pickling workers should first know the acid concentration, temperature and tonnage of the pickling pipe in this tank. \x0d\ 4) When hanging the pipe, the distance between the two slings is about 1.3m from the open end to prevent the bent steel pipe from leaking into the galvanized pipe; When lowering the pipe into the acid tank, the steel pipe should be tilted 15, and the end where you are standing should be put down first to prevent people from being injured by acid spraying. \x0d\ 5) The steel pipe weight should be 2 ~ 5 tons every 5 ~ 15 minutes. \x0d\ 6) When pickling, the steel pipe should be vibrated frequently. When vibrating, put the steel pipe flat on the horizontal bar stone of the acid tank, start the lifting belt on one side three times repeatedly, and then start the lifting belt on the other side three times after repeating it twice. The vibration rising angle shall not be greater than 15. \x0d\ 7) When the acid tank is heated, fix the steam pipe firmly first, and then open the steam valve. \x0d\ 8) When the crane pipe enters and exits the acid tank, it shall not hit the tank wall to avoid damaging the acid tank. \x0d\ 9) The main reason why the pickling of steel pipes is not in place: \x0d\ (1) Steel pipes should be strictly inspected during feeding, and unqualified steel pipes should not be put into pickling. . \x0d\ (2) The steel pipe is not operated carefully during vibration. \x0d\ (3) The pickling time and hydrochloric acid content are insufficient. The main reason for pickling \x0d\ (10) steel pipe is that \x0d\ (1) contains too much hydrochloric acid. \x0d\ (2) The pickling time is too long. \x0d\ 1 1) After pickling, check whether the outer surface of the steel pipe is smooth, whether there is residual iron scale, and whether there is oil stain on the surface of the steel pipe. \x0d\ 2。 Water washing of steel pipes: \x0d\ 1) Water washing of steel pipes should be carried out in a flowing clean water tank. When washing, all steel pipes should be immersed in water, and the pickling sling should be relaxed and hung for three or four times. \x0d\ 2) After water washing, clean the water in the steel pipe, and carry out solvent treatment as soon as possible to prevent the steel pipe from oxidation. \x0d\ 3) The standard of iron salt content in cleaning water shall not exceed the standard, and it shall be clean and transparent without other sundries. \x0d\ 4) When flushing the pipeline, operators are forbidden to cross the pickling tank to prevent people from slipping or falling into the pickling tank. \ x0d \ x0d \ solvent treatment \x0d\ 1. Put the steel pipe into the solvent tank and loosen the sling until the steel pipe is completely immersed in the solvent, and the surface of the steel pipe is not allowed to be exposed to the solvent. Wait until there are no bubbles at both ends of the steel pipe, then lift one side of the steel pipe to vibrate up and down, lift the steel pipe to control the solvent, and enter the drying table. \x0d\ 2。 In the process of solvent treatment, the inclination angle of steel pipe shall not be greater than 15. \x0d\ 3。 Soak the steel pipe in the solvent for 60 ~ 120 seconds, soak for 3 ~ 5 minutes on duty, and soak for 5 ~ 10 minutes continuously. \x0d\ 4。 Solvent temperature: keep the solvent clean at room temperature. \x0d\ 5。 Do not stick other dirt on the steel pipe after solvent treatment, and put it into the drying table for leveling; No one is allowed to step on the steel pipe placed on the drying table. If they have to go up, their feet must be coated with ammonium chloride before working on the pipeline. \ x0d \ x0d \ is drying \x0d\ 1. Placing the steel pipe treated with solvent on the drying receiving platform, and placing the end of the steel pipe at right angles on the front of the zinc pot and the front of the second magnetic roller; Straightened pipes with large curvature shall be placed at the back or on the receiving rack. \x0d\ 2。 The main function of drying kang is to dry the water on the surface of steel pipe. On the other hand, the temperature of the steel pipe itself is increased to prevent zinc from splashing and hurting people, and the heat energy in the zinc pot is not taken away, thus accelerating the formation of zinc-iron alloy layer. \x0d\ 3。 The drying temperature of kang is 80℃ ~ 65438 080℃, and the drying time of steel pipe is 3 ~ 7 minutes. The drying temperature can also be controlled according to the specifications and wall thickness of the steel pipe; Dryer should check the dryness of steel pipe at any time to prevent people from splashing zinc into zinc liquid due to lack of time; Don't overheat when drying to prevent the solvent from burning. \x0d\\x0d\ Hot dip galvanizing \x0d\ Hot dip galvanizing of steel pipe adopts the mechanical principle of inserting, pressing, screwing, pulling out and lifting the toothed disc to complete the hot dip galvanizing process. \x0d\ 1。 Process parameter control: the temperature of zinc liquid should be controlled between 440-460℃; Zinc dipping time should be controlled between 30-60 seconds; Addition amount of aluminum (aluminum content in zinc liquid level is 0.0 1-0.02%)\x0d\ 2. Zinc ingots shall be zinc ingots of national standard Zn0-3. \x0d\ 3。 Always maintain and control the reliability of the pull-in and pull-out screw and lifting device, strengthen the lubrication of the cylinder, adjust the height and angle of the galvanized pipe distributor, and adjust the equipment to the best state. \x0d\ 4。 Accurately place the proximity switch; Thermocouple wires and instruments should be of the same model, otherwise the temperature error is large, and the thermocouple protective sleeve should be checked and replaced frequently. \x0d\ 5。 The operator of the console should manually adjust the speed according to the operation of the equipment in front of the furnace and gesture instructions to prevent pipe sticking. \x0d\ 6。 The tools used by the foreman should be preheated before use to prevent zinc splashing from hurting people; Always check whether there are steel pipes falling into the pot, and clean them in time if there are any; It is necessary to adjust the equipment clamping pipe in time to ensure the safety of the equipment. \x0d\ 7。 When adding zinc to the zinc pot, the zinc ingot should be preheated first. When adding zinc, bundles of zinc are absolutely not allowed, and no more than five pieces at a time. The zinc ingot should be vertically attached to the wall of the zinc pot, and rowed slowly to avoid the zinc pot being damaged by impact and splashing a lot of zinc to hurt people; It is forbidden for iron substances to fall into zinc liquid to prevent a large amount of zinc slag from being produced. \x0d\ 8。 When melting zinc, heat slowly, and don't burn a sudden fire, otherwise it will damage the life of the galvanizing pot and a large amount of zinc vapor will evaporate. After this harmful gas is inhaled excessively by the human body, it will suffer from a "casting fever" disease. In the process of zinc melting, once the zinc has a high temperature, do not touch the zinc block with your hands to avoid burns. You should use the right tools to touch it. \x0d\ 9。 Regularly remove the zinc powder on the surface of zinc liquid. When scraping ash, gently wipe it on the surface of zinc liquid with a scraper, and don't stir it too much to avoid raising zinc ash. Don't collide with the steel pipe when the scraper is galvanized or discharged from the pipe, so as to avoid personal accidents or equipment accidents. \x0d\ 10。 Zinc blocks, ground broken zinc in front of the furnace, zinc brought out during galvanizing and zinc flowing out of steel pipes should be recovered at any time to reduce the heat loss of the zinc pot. \x0d\ 1 1。 When adding aluminum ingots on the surface of zinc liquid, it is necessary to move back and forth several times to ensure the uniform aluminum content on the surface of zinc liquid. \x0d\ 12。 In order to facilitate slag stains and zinc extraction, 20 tons of lead should be put in the zinc pot. \x0d\ 13。 During slag fishing, preheat the slag fishing machine first, store the zinc slag in large and small blocks, control the slag soaking temperature above 455℃, use special tools when swinging the slag fishing machine, and stand in a T-shape when leaving the zinc pot 1 meter. \x0d\ 14。 Hot dip galvanizing process requires strict requirements, so in the hot dip galvanizing production process, the station must work at full capacity, that is to say, the more roots or tonnage per unit time, the lower the cost, and vice versa. \ x0d \ x0d \ export and external blowing \x0d\ 1. After the galvanized pipe is discharged from the furnace, the galvanized pipe is led out by a magnetic roller table, and the number of revolutions of the lead-out machine should not be too fast, so that zinc can flow out before internal blowing. \x0d\ 2。 The angle of the outer blowing ring should be parallel to the magnetic roller at right angles, and the longitudinal and transverse positions should be positive to ensure that the galvanized pipe passes through the middle of the wind ring. \x0d\ 3。 When installing the magnetic rollers, the upper and lower five magnetic rollers must be on the same center line to ensure that the zinc layer is uniform after the galvanized pipe is blown out. \x0d\ 4。 Compressed air should be used for external blowing, and the best temperature is above 70℃ and the pressure is between 0.2 and 0.4 MPa. Adjust the wind pressure under the following conditions: \x0d\ (1), and the zinc layer on the outer surface of galvanized pipe is too thick. \x0d\ (2), the surface of zinc layer becomes dark after external blowing. \x0d\ (3)。 After external blowing, sundries and strip-shaped impurities adhere to the surface of zinc layer, and the air volume should be adjusted. \x0d\ 6。 Replace the gas ring with the same specification according to the specification of galvanized steel pipe, and the gas ring cannot be replaced with other specifications. \x0d\ 7。 It is forbidden for galvanized pipes to pass through the external blowing ring under windless conditions, so as not to block the air holes and affect the quality of external blowing. \x0d\ 8。 Always check whether the outer blowing ring is clean, whether there is zinc hanging, whether the outer surface of galvanized pipe is smooth and whether there are scratches; Whether there is zinc hanging on the surface of magnetic roller and chain, if so, it should be cleaned in time. \x0d\ 9。 Because there is no magnetic roller, the zinc layer is not firmly fixed, and the surface of the zinc layer is most easily scratched, so the speed of the pull-up roller should match the speed of the magnetic roller. \ x0d \ x0d \ internal blowing, horizontal blowing and water cooling \x0d\ 1. The hot-dip galvanized pipe is sent to the side of the internal blower through the pull-up device, and the transverse blowing is completed by approaching the switch. When the internal blowing is pressed, the pressure head rises and moves laterally to complete the internal blowing and pipe lowering actions, and the hot-dip galvanized pipe moves into the cooling water tank. \x0d\ 2。 The hot-dip galvanized pipe is most easily scratched on the roller table, mainly because the zinc is not completely solidified during the operation of the steel pipe. \x0d\ 3。 The internal blowing adopts steam purging, and the internal blowing pressure is 0.4-1.0 MPa; The inner surface of galvanized pipe after internal blowing must be smooth. \x0d\ 4。 The galvanized pipe should keep a certain inclination angle on the chain to make the cooling water flow clean. \x0d\ 5。 The working place of internal blowing is steep and the working space is small, so it must be handled carefully to prevent slipping and elbow injury; It is forbidden for high-temperature galvanized pipes to directly contact any part of the body to avoid injury. \x0d\ 6。 When working in the sink, pay attention to whether your feet stand firm and whether there are other obstacles to prevent yourself from falling into the sink; It is easy to let the chain run on the sink to prevent the flying water pipes from hurting people. \x0d\\x0d\ Passivation \x0d\ Meaning: When the parts need long-term storage and transportation, they should be passivated to prevent corrosion during storage and transportation. Its corrosion product is usually called white rust. Commonly used passivation methods are chromate method and phosphate method. \x0d\ 1。 Passivation method uses hot-dip galvanized pipe to spray passivation solution directly on the runway. Wipe the adhesion solution with a steam knife one meter away from the spraying position, and be sure to blow it clean. \x0d\ 2。 Wipe with compressed cold air, and blow off the liquid attached to the surface of the steel pipe to make the coating uniform. By adjusting the air pressure to adjust the coating thickness, there should be no excess liquid beads attached to the surface of the zinc tube. \ x0d \ x0d \ label, coil, packaging \x0d\ 1, label and coil: \x0d\ 1) When the label labeling machine is working, it is forbidden to touch the label roller by hand to prevent hand pressing; It is forbidden for double pipes to pass through the labeling machine to prevent the pressure roller from being damaged. \x0d\ 2) When the conveying roller is running, the galvanized pipe rolls the label. The labeling machine should change the injection according to different specifications, adjust the height of the primary pressure wheel when changing specifications, and refuel frequently. \x0d\ 3) Check the apron of the labeling machine frequently, and replace it in time if there is any crack. \x0d\ 4) The rubber tire should be pressed on the center line of the steel pipe, and the upper and lower fixing bolts of the pressure angle should be adjusted. \x0d\ 5) When printing the logo circle, two people should roll it at the same time, and the felt used to roll the steel pipe should be filled with ink frequently, but it is not easy to have too much ink. \x0d\ 2。 Packaging: \x0d\ 1) The baler uses air compressor with a pressure of 0.4-0.8Mpa. It is forbidden to touch the action part of the baler with your hands when the baler is working, so as not to hurt your hands. \x0d\ 2) When packing, firstly fasten the belt buckle on the packing belt, then wrap the packing belt around the steel pipe, insert the belt buckle at the other end, press the baler on the packing belt, and open the air valve of the baler for packing and compaction. The thickness of the packing belt is 1.0— 1.2mm, and the packing belt is required to be 100mm from the end, 300mm from the end and 400mm from the end with the blue bar mark. \x0d\ 3) When packaging galvanized pipes of the same specification, choose the packaging rack of the same specification, and put the galvanized pipes into a hexagon and reach the same end. \x0d\ 4) Once the outer surface of the packed steel pipe is polluted, it should be wiped clean with clean cotton sand before stacking. If conditions permit, the water in the small tube should be controlled clean; No one is allowed to step on the pipe with their feet, and the appearance quality of galvanized pipe should be maintained. \x0d\x0d\ Principle: \ x0d \ The formation process of hot dip galvanized layer is the process of forming iron-zinc alloy between iron matrix and outermost pure zinc layer. Iron-zinc alloy layer is formed on the surface of workpiece during hot dip plating, which makes iron and pure zinc layer combine well. The process can be simply described as follows: when the iron workpiece is immersed in molten zinc, zinc and α iron (body center) are first formed on the interface. This is a crystal formed by dissolving zinc atoms in matrix metal iron in solid state. When two metal atoms fuse together, the attraction between them is relatively small. Therefore, when zinc is saturated in the solid melt, the atoms of zinc and iron diffuse with each other, and the zinc atoms diffused into (or infiltrated into) the iron matrix migrate in the matrix lattice and gradually form an alloy with iron, while the iron diffused into the zinc liquid forms an intermetallic compound FeZn 13, which sinks into the bottom of the hot dip galvanizing pot, that is, zinc slag. When the workpiece is taken out of the zinc dipping solution, a layer of pure zinc is formed on the surface, which is hexagonal crystal. Its iron content does not exceed 0.003%.