The skylight to cover the corridor leading to the stairs has been conceived in corten steel dividing the 6 sections of glass, of which 3 can be opened with an electric/idraulic system and a remote control (R5). The glass section are exposed to the north, to capture as much as possible the sunlight and they are anchored to the existing concrete wall. The structure continues above the stairs forming a cusp in architectural glass and making it visible and unique, also at night because this will be illuminated form the inside. The exit double door is in Corten steel with anti panic handle and positioned in order to allow the exit and the wait of the people in case of rain. The 3 autofrettages in the basement floor are designed at their maximum size, finished with concrete as the rest of the room they face. The pavement of the corridor and the stairs is in white resins which illuminates the surroundings and reflect the light from the skylight. The white wall of the corridor will be covered with 70x70cm light wight plaster tile label panels with a waves white texture, a unique and original pattern which increase the light scattering thanks to its rough surface. The wall will host the Corten hand rail of the stairs. The above described designs will contribute to give the maximum of of visibility, respecting the environment, reflecting the spirit and the image of the premises and most importantly, they will leave a visual memory of the location to the visitors.
Corrosion behavior of low alloyed steels in acid dew corrosion environments were studied by filed exposure tests and laboratory corrosion or electrochemical measurements. Tested steels were mild steel (JIS SS400), weathering steel (0.3%Cu-0.6%Cr-0.3%Ni bearing high tensile steel, COR-TEN1), Nippon Steel), and sulfuric acid dew corrosion resistant low alloy steel 2,3) (0.3%Cu0.1%Sb bearing high tensile steel, S-TEN1, Nippon Steel). In some experiments, Type304 and Type316L stainless steel were also tested for comparison. Field tests were conducted at various exhaust gas facilities at fossil fuel fired power stations or commercial plants. In sulfuric acid dew corrosion, concentration of condensed acid is determined only with the metal surface temperature4). By using this relationship, immersion tests in various sets of acid concentration and temperature were conducted in order to compare corrosion rates of steels. Fig.1 shows effect of acid concentration / temperature on corrosion rates of steels. This result suggests that comparing to carbon steel, S-TEN1 would show lower corrosion rate in acid dew corrosion condition, where metal temperature and acid concentration are relatively lower as reported before2). A typical result of long term exposure tests in sulfuric acid dew corrosion conditions is shown in Fig.2. Test coupons were placed on the inlet duct surface to the steel stack in a high sulfur heavy oil fired power station. S-TEN1 showed clearly lower corrosion rate than COR-TEN or mild steel. As S-TEN1 does not contain chromium (<0.02%), this result demonstrates chromium is not an essential chemical element for acid resistant low alloyed steel.