Answers

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  The difference between galvanized steel pipe and galvanized welded steel pipe?

  Both galvanized steel pipe and galvanized welded pipe belong to the galvanized steel pipe series. Galvanized steel pipe is a common seamless steel pipe with a galvanized coating. Its zinc coating is generally thinner, and its advantages are higher corrosion resistance and aesthetic appearance, making it suitable for some indoor pipe installations.
  Galvanized welded pipe is a product obtained by galvanizing ordinary welded pipe. Its zinc coating is generally thicker, which has stronger corrosion resistance and a longer service life. Galvanized welded pipes are suitable for high-pressure and large-diameter pipelines, such as those in chemical, petrochemical, and power industries, as well as for outdoor pipeline installations.

  
  
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  What are the differences between high-frequency welded pipes and straight seam welded pipes?

  High-frequency welded steel pipes are produced by rapidly heating and melting the edges of the steel pipe with a high-frequency current, followed by welding under the action of extrusion rollers. This process is characterized by high welding speed and a small heat-affected zone, thus ensuring the overall performance of the steel pipe. Straight seam welded steel pipes, on the other hand, use welding rods or wires to directly weld the joints of the steel pipe. The welding process is relatively slower, and the heat-affected zone is larger.
  
  High-frequency welded steel pipes, due to the rapid heating and extrusion by the high-frequency current, have high-quality welds with high strength and a smooth appearance, making them less prone to welding defects. The high welding speed and small heat-affected zone also give the steel pipes better corrosion resistance and compressive strength during use. Furthermore, the high-frequency welding process ensures the dimensional accuracy and shape stability of the steel pipe.
  
  In contrast, the welds of straight seam welded steel pipes are relatively rough, and the weld strength may be affected by the welding process and the quality of the welding rods, resulting in some quality fluctuations. Straight seam welded steel pipes may be slightly inferior in terms of performance, especially in terms of corrosion resistance and compressive strength.
  
  Choose high-frequency welded pipe: When you need small to medium diameter, thin-walled, low-cost, high-efficiency pipelines for general transportation or structural support.
  
  Choose straight seam submerged arc welded pipe: When you need large diameter, thick-walled pipes that withstand high pressure or high stress, and where the requirements for weld quality and reliability are extremely high, such as oil and gas trunk lines and large-scale engineering structures.

  
  
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  Why do aluminum alloys require surface oxidation treatment?

  The surface oxide film on aluminum alloys can:
  a. Provide corrosion protection: The dense oxide film formed on the surface of aluminum alloys prevents corrosion from oxides in the atmosphere, thus extending their service life.
  b. Improve wear resistance: The high hardness of the oxide film improves the wear resistance and corrosion resistance of the aluminum alloy.
  c. Enhance appearance: The oxide film of different colors formed on the surface of aluminum alloys after oxidation treatment enhances their decorative and aesthetic appeal.
  d. Ensure color stability: The color of the oxide film on the surface of aluminum alloys is stable and does not easily change due to sun and rain exposure.