Analysis of pitting corrosion on steel under insulation in marine environments

• State-of-the-art review of literature on pitting corrosion.
• In-depth analysis of pitting corrosion mechanism and existing knowledge gaps.
• Analysis of pitting corrosion rate modeling.
• Analysis of fitness-for-service assessment and risk-based inspection.

Corrosion under insulation (CUI) is an important issue in marine environments. Pitting corrosion is a significant contributor to this issue. The ability to understand and model pitting behavior is integral to designing and maintaining assets in marine environments to decreased costs and increase safety and productivity. This paper reviews and analyses six categories of pitting knowledge to assess the current depth and breadth of understanding and to identify knowledge gaps in each category. The categories investigated are: identification of pitting, experimental methods, mechanism of pitting, modeling of pitting corrosion rates, remaining life assessment modeling, and risk-based inspections. This analysis finds that the depth of knowledge on pitting corrosion rate modeling and pitting mechanism is limited and requires further detailed study. The outcome of such study will strengthen pitting corrosion rate modeling, the accuracy of fitness-for-service assessments and risk-based inspection strategies.