Characterisation of pitting corrosion for inner section of offshore wind foundation using laser scanning

Abstract

Pitting corrosion is a complex mechanism and has been found in the inner sections of offshore wind structures where the standards at the time indicated that those sections were water tight and therefore free from corrosion. Pits propagate and grow in size and this can have serious implications for the structural integrity of the structure by reducing the fatigue life but also under some conditions changing to a crack whereby the damage can be accelerated. In this study, pitting corrosion is extracted from coupons exposed to the unique inner environment of offshore structures for a duration of 528–1049 days and modelled with time by extracting their geometries, such as minor length, major length and depth using laser scans. A maximum pit depth of 1.67 mm was observed. A series of analyses were run to understand the pitting mechanism and the effect of the stress concentration factor.