Long-term quantification of structural weld capacity loss due to localised corrosion

Severe localised corrosion has long been considered the main cause for structural integrity loss of steel assets exposed to aggressive marine environments, particularly as caused by pitting corrosion on or around weld zones. The weld heat affected zones for welds in steel structures are known for their higher rate of localized corrosion. The effects of corrosion losses on the structural reliability of welded mild steel, as commonly used within the offshore industry world-wide, are considered for quantifying the long-term loss of structural capacity. Apart from the expected reduction of capacity due to cross-section loss the results show that structural reliability is sensitive to likely nutrient pollution and macro-galvanic effects within the steel matrix. The possibility of localised corrosion being the result of thermal microstructural gradients produced during the welding process is discussed.