A seamless steel tube is a steel tube made from a piece of metal that has no seams on the outside. According to the production method, seamless pipe is divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, extruded pipe, pipe jacking and so on. According to the cross-section shape, seamless steel tube is divided into two kinds of circular and special-shaped, special-shaped Tube Has Square, Oval, triangle, hexagon, melon seed, Star, with wing tube many kinds of complex shapes. The maximum diameter is 650 mm and the minimum diameter is 0.3 mm. There are thick-walled tubes and thin-walled tubes, depending on the application. Steel tubes without seams along the perimeter of their cross-section. According to the different production methods, it is divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, extruded pipe, pipe jacking, etc. . Materials are ordinary and high-quality carbon structural steel, low-alloy steel alloy steel, stainless acid-resistant steel and so on. According to the usage, it can be divided into general use for water conveyance, gas pipeline and structural parts, mechanical parts and special use for boiler, geological exploration, bearing, acid-proof, etc. . USES: seamless steel tubes are used for a wide range of purposes. General purpose seamless steel tubes are rolled from plain carbon, low alloy, or alloy structural steels, with the largest output, and are used primarily as pipes or structural parts for conveying fluids. There are three types of supply according to their use: A supply according to chemical composition and mechanical properties, B supply according to mechanical properties and C supply according to water pressure test. Steel pipes supplied in Class AB shall also be subjected to hydraulic tests if they are to be subjected to liquid pressure. The special purpose seamless tube has the boiler uses the seamless tube, the chemical power uses, the geology uses the seamless steel tube and the petroleum uses the seamless tube and so on many kinds. Seamless steel pipe with hollow section, a large number of pipes used for conveying fluid, such as oil, natural gas, gas, water and some solid materials, such as pipes. Compared with solid steel such as round steel, steel pipe has the same bending and torsion strength and light weight. It is an economical cross-section material.