GB 3087 Grade 20 boiler pipes are usually made of low carbon steel, which has good weldability and mechanical properties. Grade 20 indicates its specific chemical composition and strength properties.

ASTM A335 pipes are made from various grades of ferritic alloy steel, which typically include chromium and molybdenum as key alloying elements.

ASTM A209 is a standard specification for seamless carbon-molybdenum alloy-steel boiler and superheater tubes.

The carbon content of T22 alloy pipe is less than 0.15%, and the composition also contains elements such as manganese, phosphorus, sulfur, silicon and molybdenum. The maximum hardness of this steel pipe is 163 HB, the minimum yield strength is 205MPa, and the minimum tensile strength is 415MPa.

ASTM A199 specifies several grades of alloy steel tubes, including Grade T4, T5, T9, T11, T21, T22, T91, and T92. Each grade is designed for specific high-temperature and corrosion-resistant applications.

ASTM A179 tubes are made from low-carbon steel, typically with a carbon content of 0.06-0.18%. This low carbon content makes the tubes suitable for bending, flaring, and other forming operations while maintaining good heat transfer properties.