Abstract
Austenitic stainless steels have been extensively used as piping and fitting materials in special ship constructions such as FPSO/LNG carriers to increase their expected life expectancy in corrosive environments. However, in the presence of chloride ions, contaminants and mechanical damages, stainless steel can lose its passivity and could cause pitting corrosion. An alternative method for protecting stainless steels from localized corrosion can be the use of coatings. The effects of a coating application on the anticorrosive performance of the stainless steel substrate are not well established.
The present study evaluates the corrosive behavior of coated stainless steel using the following surface treatment method: pickling, solvent cleaning, and non-metallic blasting (garnet blasting). The results suggest a beneficial role for commercially modified epoxy-polyurethane topcoat application, which is confirmed by cyclic corrosion test of painted stainless steel samples. Artificial thermal shock using liquid nitrogen, pull off strength and electrochemical test results indicate that pickling and degreasing (solvent cleaning) as well as garnet blasting can be applied as surface treatment methods to maintain effective coating properties between the modified epoxy primer-polyurethane topcoat system and the stainless steel interface.
Based on these results, applying coating system on stainless steel surface can be more effective in terms of corrosion resistance than only passivation treatment during continuously exposed in marine atmospheric environment.
