Technical information

ArcelorMittal welded hollow sections can be produced by three different manufacturing methods:

Cold forming
Cold-formed hollow sections are manufactured through the continuous forming at room temperature of a steel strip passing through forming stands that progressively bend it into a circular shape. This circular shape then enters a welding stand that joins the strip edges together in a continuous longitudinal weld seam. After the welding station, the outside seam of the circular tube is removed, and the final shape (circular, square, rectangular) and precise dimensions of the tube are achieved by passing it through sizing stands.

A cutting saw then divides the length of the welded tube into standard or customised lengths as required. Weld seams are ensured via electromagnetic NDT inspection.

These products meet all of the EN 10219 standard requirements.

Hot forming (stretch reduction)
Hot-formed hollow sections are manufactured by firstly obtaining a cold-formed hollow section (a mother tube) through the continuous forming at room temperature of a steel strip passing through forming stands that progressively bend it into a circular shape. This circular shape then enters a welding stand that joins the strip edges together in a continuous longitudinal weld seam.

The mother tube then passes through a continuous furnace to heat the full length of tube in order for it to become malleable. It is then passed through several hot rolling stands to reduce its diameter and thickness to achieve its final shape and precise dimensions (circular, square, rectangular).

These products meet all of the EN 10210 standard requirements.

Hot finishing
Hot-finished hollow sections are manufactured by firstly obtaining a cold-formed hollow section (a mother tube) through the continuous forming at room temperature of a steel strip passing through forming stands that progressively bend it into a circular shape. This circular shape then enters a welding stand that joins the strip edges together in a continuous longitudinal weld seam. After the welding station, the outside seam of the circular tube is removed, and the final shape (circular, square, rectangular) and precise dimensions of the tube are achieved by passing it through sizing stands.

After cutting, the obtained tube (in its definitive shape) is heated in a furnace in order to release any internal residual stress.

These products meet all of the EN 10210 standard requirements.