In 1996, a fire destroyed part of Düsseldorf airport and for safety reasons the authorities decided that it should be completely rebuilt. Ilta Inox (Italy) was called in to develop a new product to be used in the external canopy structure. An order was placed for 53,000 metres of TIG-welded EN 1.4404 (AISI 316L) tube in fixed lengths of between 6 and 12 metres. Following the TIG welding phase, the tubes were subjected to chemical pickling and passivation treatment, utilising a nitric-hydrofluoric acid bath to eliminate any trace of ferrous contamination and surface oxides.
The characteristic feature of this order lay in the surface finish of the tubes, obtained through an appropriate use of pickling. The most important problem to be resolved concerned the need for the tubes to absorb rather than reflect sunlight so as not to create problems for pilots as they were landing their aircraft. The order was executed in time for the faculty to be inaugurated during the summer of 2001. A second order for 30,000 metres is currently being completed.
(From âInossidabileâ? 148, June 2002)
