Seamless steel pipe is hollow section, a large number of used for conveying fluid pipe, such as oil, natural gas, coal gas, water and some solid materials, such as pipelines. Compared to the steel pipe and round steel solid steel bending torsional strength phase at the same time, the weight is lighter, is a kind of economic cross section steel, widely used in the manufacture of structural and mechanical parts, such as petroleum drill pipe, auto transmission shaft, bicycle frame, with steel pipe manufacturing annular parts, can improve the material utilization, simplifying the manufacturing process, material saving and processing time, such as rolling bearing ring, jack sets, at present has been widely made from steel pipe. Steel pipe or all kinds of conventional weapons indispensable materials, gun, gun barrel to steel pipe manufacturing. Steel pipe according to the cross-sectional area in the shape of different can be divided into circular tube and special pipe. Due to the equal conditions, the circumference circle area is the largest, with circular tube can deliver more fluid. In addition, the circle cross section under radial pressure, the internal or external stress is relatively uniform, therefore, the vast majority of steel tube is round tube.
Seamless steel pipe standards: GB/T8162-2008 GB/T8163-2008 ASTM A501-98 ASTN JIS G3441 A519-98-98, etc.