A brief introduction to square and rectangular tubes

Hollow section are rigid steel structures with high strength-to-weight ratio. Common applications include stair bars and viaduct structures, and are also widely used in building structures. Hollow section usually have two standard cross-section shapes, that is, square hollow profiles and rectangular hollow profiles, that is, square tubes and rectangular tubes.

So what is a square tube and what is a rectangular tube?

Square tubes is a hollow section of light thin-walled steel tube, also known as cold-formed steel products. It is usually made of Q235 hot rolled or cold rolled steel strip or coil as raw material, and is welded by high frequency after cold bending to form a specific square cross-section size. Compared with ordinary steel pipes, hot-rolled thick-walled square pipes have significant advantages in wall thickness uniformity, corner size and edge flatness, and have excellent mechanical properties, corrosion resistance and low temperature toughness.

Rectangular tubes, also known as flat square tubes, have a rectangular cross-section, which can provide good bending and torsional strength, and are widely used in engineering and mechanical manufacturing because of their light weight.

Main use

Square and rectangular tube applications cover a number of areas:

Pipe: mainly used in building structure, machinery manufacturing, steel structure engineering, shipbuilding, automobile chassis, bracket, pressure vessel, bridge and other fields.
Rectangular pipe: widely used in fluid transport pipelines (such as oil, gas, water and steam), as well as in machine parts, engineering structures and weapon manufacturing in the defense industry.

Production technology

Square tubes are manufactured by two main production methods: hot rolling and cold rolling

Hot rolling: hot rolled strip steel as raw material, through processing and rolling molding.
Cold rolling: Hot rolled coil as raw material, after pickling to remove the oxide skin and cold rolling. The hardness and strength of cold-rolled steel pipe are increased, but the toughness is reduced, so it is suitable for the manufacture of simple deformed parts. After the continuous annealing process after cold rolling, the finished product quality is higher, the surface is more beautiful, and the dimensional accuracy is better than that of the hot rolled pipe.

Molding process

Real bending: Real bending means that the inner and outer walls of the inner and outer rollers and the tube blank are compacted at the same time when the material is bent, forming accurately and the inner Angle radius is more accurate. The disadvantage is that the bending area will produce stretching and thinning effects.
Hollow bending: The hollow bending process relies on the unidirectional contact between the outer roller and the outer wall of the tube blank to achieve the forming. It is characterized by the ability to process some complex cross-section shapes, but because of the uneven pressure during the formation process, it is easy to appear the problem of edge instability or surface depression.

The difference between square and rectangular tubes

Section shape: The section of the square tube is square, while the section of the rectangular tube is rectangular.
Functions and uses: Square tubes are usually used for load-bearing structures, such as building frames and engineering equipment; Rectangular tubes are better suited for fluid transport, lightweight structural design, and the defense industry.
Relation: Square tubes are actually a subcategory of rectangular tubes with a more special cross-section shape.

Because of its various performance characteristics and wide applicability, square pipe has become an important basic material for modern industrial manufacturing.