In the world of engineering and construction, the acronyms RHS, SHS and CHS are often used.  This is most common in the United Kingdom and associated countries, including Australia and New Zealand.

The term RHS stands for Rectangular Hollow Section. RHS is the most prevalent term and is generally accepted for describing square hollow section as well, which is technically incorrect.

The correct term for square tube is SHS which stands for Square Hollow Section. Less known is the term CHS, this stands for Circular Hollow Section.

These terms are widely used to describe mild steel; however, they can also be translated for stainless steel and aluminium engineering and construction by engineers who are familiar with the terminology.


Other common terms include Box Section, Extrusion and Profile. Box Section can refer to either rectangle tube or square tube. Extrusion and Profile are terms that can be used in place of ‘Section’; however, this is more applicable to material which has been particularly configured or shaped rather than rectangle, square or circular hollow tube.