CSA G40.21 is the Canadian specification for rolled or welded structural-quality steel. Atlas Tube produces hollow structural sections (HSS) to this spec in round, square and rectangular shapes and a range of sizes and wall thicknesses.
CSA G40.21 HSS are welded or seamless round, square, rectangular and special-profile structural tubing products.
There are two types of HSS in accordance with this spec — Class C and Class H. Atlas Tube produces both. Class C HSS are cold-formed either through a seamless process or an automatic electric-welding process producing a continuous weld. Class H HSS are also cold-formed, but then heat-treated in order to stress-relieve the product. Tensile samples (heat-treated with the load) are pulled, and the results are recorded for each heat number, tube size and gauge. The material is then checked for straightness and surface condition.