Materials of Construction

Stainless steels are Iron-based alloys with at least 12% Chromium. Corrosion resitstance is a function of composition, heat treatment, surface condition and fabrication. Chromium is the essential element in forming a passive film spontaneously with oxygen. Higher Chromium contents (maximum is approx. 30%) leads to improved passiviation and corrosion resistance. SS 316 Tl is the material of choice for use with organic solvents or organic acids. This is the standard material in chemical engineering. Only few acids and halides can attack this steel. Care is also necessary with halogen salts. Halides can cause cracking due to stress corrosion at temperatures above 100°C.