Steel grades for hot-finished and cold-formed structural hollow sections

BS EN 10210, BS EN 10219 and BS 7668:2016

Structural hollow sections are closed profiles that are either cold-formed or hot-finished. The properties and suitability of each product varies and care must be taken to specify the correct material standard. Cold-formed hollow sections exhibit residual stresses and have a heat-affected zone (HAZ) at the weld seam – because of this, cold-formed hollows are typically unsuitable for more onerous fabrications. It is crucial that the standard is stated alongside the selected steel grade when specifying hollow sections, for example:

The National Structural Steelwork Specification (NSSS) (BCSA, 2020) advises that unless cold-formed hollow sections are explicitly specified, hollow sections should be assumed to be hot-finished.