In Italy a World War II air-raid shelter has been expanded in order to hold a gigantic purification system capable of doubling previous capacity. The tunnel, whose width varies between 15 and 20 metres, with a maximum height of 15 metres, has an annual purifying capacity of 16 million cubic metres. When setting up the technological system, EN 1.4301 (AISI 304) stainless steel was used for all piping and connectors, including flanges and bolts, and EN 1.4401 (AISI 316) for the lines conveying ozone and chemical additives. The idea of using stainless steel came about when considering potential maintenance of the system. The metal parts in the cave are subject to dew and therefore the formation of condensation on their surface, which, on traditional metal materials would require frequent surface protection. Moreover, stainless steel does not release pollutants into the drinking water with which it comes into contact.
From: Inossidable 150. Author: ACSM.
