Square / Rectangular Steel Box Sections

Square and rectangular steel box sections are lengths of hollow box section steel with a rectangular profile, curved corners and a hollow centre. They are some of the most versatile mild steel box sections, with applications ranging from cabinet making and light fabrication, through to their use as pipes and conduits. James Dunkerley Steels supply rectangular box section steel in a range of cross-sectional sizes and thicknesses, to suit a highly diverse variety of applications.

Of course, a square is simply a rectangle whose sides are all the same length, but for simplicity’s sake they tend to be listed as a separate product category entirely.

Steel box section sizes

Our square hollow sections steel dimensions begin at a size of 40mm x 40mm and a thickness of 3.0mm, and go up to a maximum of 400mm x 400mm and 20.0mm thick.

The width measurement is the outer dimension, while the thickness of the steel will determine the size of the inner dimension of the cavity itself.

Where the size of the inner cavity is significant, the width specified should therefore be based on the minimum acceptable cavity size, with the thickness of the steel added to this twice, once for each parallel side of the square.

Rectangular hollow section sizes start from 50mm x 30mm and 3.2mm thick, although some larger sizes can be specified at 3.0mm thick.

Our largest standard size for rectangular steel box sections is 500mm x 300mm and 20.0mm thick.

Steel box section sizes are usually specified as width x height in mm. For a rectangular box section these will be different dimensions; for a square box section they will be the same. A third parameter is also specified: the thickness of the steel.

The thickness of the walls influences the strength of rectangular box section steel, but also the weight, so it’s important to take both into account when ordering.

Find full details in our downloadable PDF technical data sheets, or just ask and we’ll be happy to help you decide what size of square or rectangular box section you need.