Seamless steel pipe has a hollow section. The seamless pipes are widely used for conveying fluid, such as the transmission of oil, natural gas, gas, water and some solid materials. Compared with round steel and other solid steel, the seamless pipe has light weight under the same bending strength. The seamless pipe is an economic section of steel, which is widely used in the manufacturing of structural parts and mechanical parts, such as oil drill pipe, car drive shaft, bicycle frame construction and etc.

Straight steel pipe(general pipe) is used to transport low pressure fluid. The materials have Q195, Q215A, Q235A steel, Q235B carbon. Straight steel pipe could also be manufactured by easy welding 0317, standard model 6012, steel mother 755, mild steel and etc. Steel pipe should be through some tests such as water pressure, bending, flattening and so on. The surface quality has certain requirements. In general, the delivery length is 4-10m. The specifications of the welded pipe are denoted by nominal caliber (mm or inch). Nominal caliber is different from the actual one. The welded pipe has two kinds including ordinary steel pipe and thickened steel pipe according to the specified wall thickness. The pipe could be divided into two types: with thread and without thread.