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 to extruded and drawn tubes is the possibility 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 having the advantage of very good dimensional stability.