Field study investigations of the impact of shape, size and orientation on dry deposition induced corrosion of galvanized steel

Abstract

A controlled field study was conducted at Research Triangle Park, NC, to determine how shape, size and orientation of galvanized steel structures affect (1) dry deposition of SO x and NO x compounds and (2) dissolution of Zn corrosion products resulting from such deposition. Thirteen structures of various shapes, sizes and orientations were exposed to dry deposition only for 100 weeks, during which they were rinsed with deionized water every 2 weeks and the rinses were analysed for Zn, Ca, and their ionic contents. The rinse data are consistent with size, orientation and exposure history affecting dry deposition of SO 2− 4 precursors such as SO 2. Dry deposition of precursors of surface NO − 3, including HNO 3, is affected by structure size. A model regression equation is presented that shows that Zn dissolution can be explained in terms of the SO −2 4 and NO − 3 rinse concentrations. The experimental results suggest that there is likely to be some error associated with extrapolating galvanized steel test panel results to actual structures.