The square steel pipe is a term for square pipes which have the equal side length and rectangular pipes which have the unequal side length. The square steel pipe is made by the strip steel with the rolling process. Generally, the strip steel will be unpacked, flattened, curled and welded to be a round pipe, be rolled into a square pipe, and will be cut into the needed length. Square steel pipes are mainly used in fields including the mechanical industry, the chemical industry, shipbuilding, oil casings and pipelines for transporting water, gas, sewage, etc.

The classification of square steel pipes according to materials

According to materials, the square steel pipe can be divided into the common carbon steel square pipe and the low alloy square steel pipe.

The classification of square steel pipes according to production processes

According to production processes, square steel pipes can be classified into the hot rolled  seamless square pipe, the cold drawn seamless square pipe, the extruded seamless square pipe and the welded square pipe.

Welded square steel pipes can be further divided into the arc welding square pipe, the ERW square pipe (high frequency, low frequency), the gas welding square pipe and the furnace welding square pipe according to the process; the longitudinal welded square pipe and the spiral welding square pipe according to the welding seam.

The classification of square steel pipes according to surface treatments

According to production processes, square steel pipes can be classified into the hot galvanized square steel pipe, the electrogalvanizing square steel pipe, the oiled square steel pipe and the acid pickling square steel pipe.