STRESS-CORROSION CRACKING OF SENSITIZED 304 AUSTENITIC STAINLESS-STEEL IN PETROLEUM REFINERY ENVIRONMENT

Samans solution represents the polythionic acid solution formed in petroleum refineries during shutdown as a result of the interaction of the sulfide scale on the steel surface with moisture and oxygen at ambient temperatures. Chemical analysis of the solution revealed that it contained seven different constituents varying in concentration. They are sulfuric, sulfurous, and thionic acids (di-, tri-, tetra-, penta-, and hexathionic acid). Only tetrathionic acid induced stress corrosion failure.