Rainfall distribution model and atmospheric corrosion protection grade based on numerical simulation

Purpose Traditional atmospheric corrosion evaluation methods are mostly based on regional-scale meteorological parameters or standard sample corrosion rates, which struggle to reflect the spatially non-uniform corrosion exposure characteristics caused by wind-driven rain, building sheltering, local bypass flow and differences in water collection and drainage in actual engineering structures. This study aims to enhance the refinement level of material corrosion protection level classification, this paper proposes an atmospheric corrosion protection level classification method based on a rainfall-on-ground model. Design/methodology/approach By integrating wetting time index and effective salt retention index, the corrosion exposure index (CEI) is established and the study area is divided into five atmospheric corrosion protection levels, P1–P5, based on the index value. Findings Taking regional terrain and buildings as examples, this paper introduces the local capture rate to convert standard horizontal rainfall into actual rainfall at different locations on material surfaces or the ground, thereby achieving the transition from a regional scale to a local scale in corrosive environments. Originality/value The method in this paper can extend the traditional regional average corrosion assessment to spatially resolved local corrosion risk assessment, providing a quantitative basis for material selection, protective system design, corrosion monitoring point layout and service maintenance strategy formulation.