Welded tubes are made from hot rolled or cold reduced strip, sheet or plate. Welded tube includes hollow sections, black and galvanised gaswater pipe, scaffolding tube and large diameter pipe. Small and medium diameters are produced in continuous, multiple-roll mills that progressively bend incoming, unheated strip into a circular cross-section prior to welding along the longitudinal seam. Tube may subsequently be cold-drawn through dies to achieve precise dimensions and finish. Large diameters (400-1,600mm) are made from discrete plate which is welded in an "O" shape before being mechanically or hydraulically expanded. Spiral welded tubepipe is available in diameters up to 2,500mm.
Welded tubes are used in a wide range of general engineering applications as well as in power generation plants, oil refineries, automotive manufacturing and furniture production.