Failures and maintenance costs of corrosion to metal structures and system ais so significant and costly. Stainless steel as the most vastly used material is commonly assumed to be resistant to corrosion and with high strength. Stainless steel has developed very fast and many new brand stainless steels are coming into the market. New family of stainless steel, namely dupelxx stainless steel is offering its better features with considerably lower cost.With the advent and success of this type of stainless steel, many researchescall 1990's as "The Duplex Decade". However, most vigorous environment, even stainless steel will fail. Stainless steel susceptibility towards certain environment and application always need to be verified through experiment in-site or in laboratory, simulated or real concition. Through this final year project, we make the overview of stainless steel families, especially to duplex stainless steel and the effects of different alloying elements. Corrosion in general and specifically to localized corrosion are discussed. Three types of stainless steel, namely DP3, Zeron 100 (super duplex stainless steel) and 254SMO(super austenitic stainless steel) of Sumitomo, Weir and Avesta respectively,were exposed to crevice corrosion test in transported tropical sea water for 80 days. The corrosion potential and corrosion appearance were checked. Metallurgical aspect were studied in term of susceptibility and of metallurgical changes due to corrosion. Finally, the most corrosionresisteant material to tropical sea water under crevice is validated. As the pilot study in this area, we end this study with valuable proposals for the following students taking this topic.