SR288 Update of New Zealand's atmospheric corrosivity map (2013)

Atmospheric corrosion testing was conducted at 39 exposure sites across New Zealand. The corrosion rates of mild steel and hot-dip galvanised zinc-coated coupons were measured after 1 year of exposure and were compared with those obtained in the original BRANZ surveys of the 1980s to determine whether atmospheric corrosion behaviour of metals has changed over the past three decades.

No nationwide, universal trend was found in the results of this current work, as the changes in corrosion rates derived at different sites exhibited different relative behaviours. At a limited number of sites, the new corrosion rate data for mild steel and/or zinc was significantly different from the old data. However, at most sites, the new data appears to be comparable with the old data, indicating that a more complete atmospheric corrosion rate data set can be established by combining BRANZ previous and present studies.