Modeling of Pitting of Heat Exchangers Made of 18/10 Type Steel in Circulating Waters

Mathematical models have been developed which describe the dependences of critical pitting temperatures of 12Kh18N10T, 08Kh18N10, AISI304 and AISI321 steels in model circulating waters with pH 4–8 and chloride concentration 350–600 mg/L on chemical composition and structure. They are based on multidimensional first-order regressions and on neural networks of direct signal propagation. The analysis of mathematical models shows that the critical pitting temperatures of these steels increase with increasing pH of circulating waters and decreasing chloride concentration, the average distance between oxides and nitrides of titanium and the number of the smallest (up to 1.98 μm) oxides. The influence of chloride concentration in circulating waters and the above-mentioned indicators of steel structure is the most significant, and the influence of their chemical composition within the standard is absent. It is proposed to use the developed mathematical models to select the optimal melting of steels of the 18/10 type according to their pitting resistance and its prediction during the operation of heat exchangers in circulating waters.