Effect of Surface Imperfection Affecting Long-term Durability of Coating Performance Offshore Coating System

摘要

In case of offshore platforms,they are operated for more than 30 years in severely corrosive environment.It is necessary to keep high quality coating performance for long-term operation period without appropriate maintenance.The performance of coating is significantly influenced by its adhesion property to the substrate material and steel preparation is the essential first stage treatment of a substrate before the application of all kinds of coatings.With regard to steel preparation,ISO 8501-3 specifies preparation grade of welds,edges and other area with surface imperfection.The interpretation of preparation grade varies depending on viewpoints of client superintendent because it is a visual assessment standard without quantitative grade.To study the effect of surface imperfection affecting long-term durability of film performance on offshore coating system,carbon steel surfaces were prepared by various preparation grade based on ISO 8501-3 for weld profile,weld porosity and thermally cut edge.This study deals with the correlation between surface imperfection and coating performance evaluated by NORSOK M-501 and ISO 20340 test method including ageing resistance test and sea water immersion test for 6 months.