Characteristics of Seamless Tubes

The fluid seamless tube has a hollow cross section, and is widely used as a pipeline for transporting fluids, such as a pipeline for transporting oil, natural gas, coal gas, water, and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter in weight when the flexural and torsional strength is the same, and is an economical cross-section steel. It is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, and bicycles Frames and steel scaffolds used in construction are used to make ring parts made of steel pipes. Seamless pipes for special purposes include seamless pipes for boilers, chemical power, seamless pipes for geology and seamless pipes for petroleum.

The characteristics of seamless tubes are as follows:

The excellent corrosion resistance of stainless steel seamless pipes is due to the formation of an invisible oxide film on the surface of the steel, which makes it passive. The formation of the passivation film is due to the reaction of steel with oxygen when exposed to the atmosphere, or due to contact with other oxygen-containing environments. If the passivation film is damaged, the stainless steel seamless pipe will continue to corrode. In many cases, the passivation film is only destroyed on the metal surface and local areas. The role of corrosion is to form small holes or pits, which produce irregularly distributed small pit-like corrosion on the surface of the material.

Generally, seamless tubes are made of high-alloy carbon steels such as 10, 20, 30, 35, 45 and other low-alloy structural steels such as 16Mn and 5MnV or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other combined steels by hot or cold rolling. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. Seamless tubes made of medium carbon steel such as 45 and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Generally, seamless tubes are used to ensure the strength and flattening test. Hot-rolled steel pipes are delivered in hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in hot-treated state. Seamless pipes for low and medium pressure boilers: used to manufacture various low and medium pressure boilers, superheated steam pipes, boiling water pipes, water-cooled wall pipes and superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes for locomotive boilers.