Differences in Atmospheric Corrosion Severity Over Long and Short Distances

Abstract

Environmental severity indices (ESIs) are commonly used to designate corrosion severity of different locations and have a huge potential to be used to guide corrosion prevention and maintenance practices. Prior research has focused on large-scale differences in atmospheric and climate conditions to explain differences in corrosiveness. Differences in corrosion severity across very small distances in the form of pitting have also been extensively studied and modeled. In pitting, severe corrosion can occur within a pit, while leaving nearby nonpitted areas largely unaffected. However, relatively little work has been done exploring the effects that can cause differences in corrosion at length scales between these two extremes. This work has combined several corrosion datasets to analyze and discuss corrosion differences across these various, mid-level length scales and the possible causes of these differences. Analysis indicated that proximity to saltwater is one factor that can drive large differences in corrosion severity across distances of less than 1 mi. Factors that may affect corrosion at even more granular levels are also considered and discussed, such as sheltering from atmospheric deposition, shading from sunlight, exposure height above the ground, and water retention due to sample geometry. Recommendations for future study and ESI development based on the findings in this combined dataset were given.