ABSTRACT: The S-H2O and Fe-S-H2O diagram are drawn for sulpher water systems. These diagrams show that within the range of pH 7 to 14, the sulfur species present in the solution could be HS-, to some extent S2-, S2O32- and SO32-. The E-pH diagram of Fe-S-H2O shows that corrosion products forming on SS304L will be pyrite or iron oxide and on duplex steel SS2205 it could be pyrrhotite/troilite/mackinawite depending upon the potential. Except mackinawite and troilite, other sulfides /oxides provide protection. This could be the reason for observing lesser corrosion rates in stainless steels.
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