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How are seamless steel pipes classified?
Release time:
2022-07-28
To improve the corrosion resistance of seamless steel pipes, general seamless steel pipes (black pipes) are galvanized. Galvanized seamless steel pipes are divided into hot-dip galvanizing and electro-galvanizing. Hot-dip galvanizing has a thicker zinc coating, while electro-galvanizing has a lower cost.
To improve the corrosion resistance of seamless steel pipes, general seamless steel pipes (black pipes) are galvanized. Galvanized seamless steel pipes are divided into hot-dip galvanized and electro-galvanized types. Hot-dip galvanized pipes have a thick zinc coating, while electro-galvanized pipes have a lower cost. Oxygen blowing pipes: Used as oxygen blowing pipes in steelmaking, generally using small-diameter welded seamless steel pipes, with specifications ranging from 3/8 inch to 2 inches in eight types. Made from 08, 10, 15, 20, or Q195-Q235 steel strips. For corrosion prevention, some undergo aluminizing treatment. Galvanized seamless steel pipes are divided into cold-galvanized pipes and hot-galvanized pipes; the former has been banned, while the latter is still temporarily permitted by the state. Hot seamless steel pipes: Involves a reaction between molten metal and the iron matrix to create an alloy layer, combining the matrix and coating. Hot-dip galvanizing first involves pickling the seamless steel pipe to remove surface iron oxide. After pickling, it is cleaned in a solution of ammonium chloride or zinc chloride, or a mixed solution of ammonium chloride and zinc chloride, before being sent to a hot-dip galvanizing tank. Hot-dip galvanizing has the advantages of a uniform coating, strong adhesion, and long service life.
Hot-dip galvanized seamless steel pipes: The seamless steel pipe substrate undergoes complex physical and chemical reactions with the molten plating solution, forming a corrosion-resistant, tightly structured zinc-iron alloy layer. The alloy layer, pure zinc layer, and seamless steel pipe substrate are integrated. Therefore, it has strong corrosion resistance. Cold seamless steel pipes: Cold galvanizing is electro-galvanizing, with a very small amount of zinc plating, only 10-50g/m2. Its inherent corrosion resistance is significantly lower than that of hot seamless steel pipes. Reputable seamless steel pipe Manufacturers, in order to ensure quality, mostly do not use electro-galvanizing (cold galvanizing). Only small-scale enterprises with outdated equipment use electro-galvanizing, and their Price is relatively cheaper. Currently, the Ministry of Construction has officially issued a document eliminating the technologically backward cold seamless steel pipes, and cold seamless steel pipes will no longer be permitted for use in water and gas pipes. Cold-galvanized seamless steel pipes: The zinc layer is an electroplated layer, independent from the seamless steel pipe substrate. The zinc layer is thin and simply adheres to the seamless steel pipe substrate, making it easy to peel off. Therefore, its corrosion resistance is poor. In newly built residential buildings, the use of cold-galvanized seamless steel pipes as water pipes is prohibited. Calculation formula for the weight per meter of seamless steel pipes: [(outer diameter - wall thickness) * wall thickness] * 0.02466 = kg/meter (weight per meter).
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