Difference between Hot Galvanized Steel Pipe and Cold Galvanized

  1. Hot-dip galvanized pipe:
    Hot-dip galvanizing tube is to make the iron base and molten metal react to form alloy layer, so that the base and the coating bond. Hot-dip galvanizing requires pickling to remove iron oxide from the surface of the steel pipe. After pickling, it is washed in aqueous zinc chloride solution or ammonium chloride or mixed aqueous solution of ammonium chloride and zinc chloride, and then fed into a hot dip plating bath. Hot-dip galvanizing has the advantages of strong adhesion, uniform coating and long service life.
  2. Cold galvanized pipe:
    Cold galvanizing is what we call zinc plating. The amount of galvanization is very small, and the corrosion resistance of the cold galvanized pipe is very different from the hot galvanized pipe, so many construction projects do not use the cold coated pipe. At present, the Ministry of Construction has officially declared that the backward technology of cold galvanizing pipe needs to be eliminated, and the cold galvanized pipe is not allowed to be used as a water gas pipeline in the future.
    Applications of galvanized steel pipe:
    Hot-dip galvanized steel pipe is widely used in construction, machinery, coal mine, chemical, electric power, railway vehicles, automobile industry, highways, bridges, containers, sports facilities, agricultural machinery, petroleum machinery, survey machinery and other manufacturing. Welded steel pipe with hot-dip or electroplated zinc coating on the surface of galvanized steel pipe. Zinc plating can improve corrosion resistance of steel pipe and prolong its service life.
    Galvanized pipes are widely used, not only as pipelines for transporting water, gas, oil and other general low-pressure fluids, but also as oil well pipes and oil pipelines in the petroleum industry, Especially in the submarine oil field, the oil heater, the condensation cooler, the chemical coking equipment in the coal distillate wash oil exchange pipeline, the trestle pipe pile and the mine laneway support frame pipeline and so on.
    Therefore, in the choice of galvanized steel pipe, we should focus on quality, choose high quality, high price galvanizing steel pipe. The choice of pipeline has a great impact on the quality and safety of construction projects.
    Hot-dip galvanized steel pipe: hot-dip galvanizing steel pipe is first steel parts for pickling, in order to remove iron oxide on the surface of steel parts, After pickling, it is cleaned in a bath of ammonium chloride or zinc chloride aqueous solution or mixed aqueous solution of ammonium and zinc chloride, and then fed into a hot dipping bath. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life.
    Cold galvanizing steel pipe: Although now cold galvanized steel pipe has rarely been used on a large scale but since we tell the difference nature will also introduce under, Cold galvanizing is also called electroplating zinc, is the use of electrolysis equipment will be the pipe after oil, pickling into the composition of zinc salt solution, The anode of the electrolytic equipment is connected, and a zinc plate is placed on the opposite side of the tube. The positive electrode connected to the electrolytic device is connected with the power supply. The directional movement of current from the positive to the negative electrode can deposit a layer of zinc on the tube. The cold plating tube is processed first and galvanized later.
    To talk about the differences, we have to talk in several ways.
  3. Different from the construction process: hot-dip galvanized steel pipe is to make molten metal and iron matrix reaction to produce alloy layer, so that the base and coating combined with the two and cold galvanized steel pipes are cold galvanized coating mainly through the electrochemical principle to anti-corrosion.
  4. Different equipments required: pickling equipment, bottom withdrawal annealing furnace or hood annealing furnace. Cold galvanized steel pipe: electrolysis equipment.
  5. Different performance: durable corrosion resistance, standard quality of hot dip galvanizing thickness makes it has excellent durability; The toughness of the coating is strong, hot dip galvanizing layer forms a unique smelting metal structure, this metal structure can withstand the transport and use of mechanical damage. Cold galvanizing: excellent environmental performance. Most solvents and diluents for cold galvanizing do not contain toxic organic solvents. Moreover, the evaporation of organic solvents is reduced, energy consumption is reduced and the process is beneficial to environmental protection.
  6. Zinc coating thickness is different thickness: hot-dip galvanized steel tube zinc layer itself is relatively thick, there is more than 10 um thickness, although the surface is bright, but rough, there will be zinc flowers. And galvanized (cold galvanized steel pipe) zinc layer is very thin, as long as the thickness of 3-5um, although the surface is smooth, but there will be dark, dirty performance, good processing performance, lack of corrosion resistance.
  7. Different applications: hot-dip galvanized steel pipe due to good corrosion resistance, Hot-dip galvanized steel pipe is widely used in power tower, communication tower, railway, highway protection, lamppost, marine components, building steel structural components, auxiliary facilities of substation, light industry and so on. Cold galvanized steel pipe is the main development direction of environmental protection of heavy corrosion protection coatings.