Welded tubes are manufactured by forming a flat strip of aluminium and then joining the edges by a high-frequency welding process.
The main difference with welded tubes, as opposed to extruded and drawn tubes, is that it is possible with welded tubes to have a multi-layer material of different aluminium alloys. The clad layer is widely used in tubes for heat exchanger production to enable furnace or flame brazing, and to give sacrificial corrosion resistance.
For industrial applications, where strength and formability are important factors, 5xxx-series alloys can be utilized. This gives the advantage of very good dimensional stability.