In the oxidation unit system of the PTA device of a chemical plant, the content of iron ion increased. The increased iron
ion has already influenced the result of oxidation reaction, threatened the steady production seriously. Analytical results show that the iron ion mainly comes from the corrosion of 316L stainless steel packing of T-403 solvent recovery tower. By some modern physical detective technologies and chemical analysis methods as scanning electron microscopy, electronic probes, metallurgical analysis, the corrosion profiles, chemical composition and element distribution of stuffing from T-403 tower were observed. Metallurgical structures and mechanics properties were compared in stainless steel using and without using stuffing. Corrosion mechanism of
stainless steel stuffing was researched. The test result shows that relatively serious local corrosion has happened in the stuffing sample. The characteristic is intergranular corrosion and pitting. After the packing is corroded, the tensile strength and rigidity are all obviously reduced. Intergranular corrosion arises from the lack of chromium. While pitting was caused by the damage of local passivation film and Br~- in
acetic acid solution.The original packing material has the problem of quality, the carbon content of the stainless steel packing has not reached the standard of the ultralow carbon 316L stainless steel.