Narivsky A. Regularities and mechanisms of local corrosion of corrosion-proof steels and alloy of an austenitic class for capacitive and heat-exchange equipment

The object of research is local corrosion of corrosion-resistant steel and alloys of austenitic class in corrosive environment. The purpose is to determine the common trends of local corrosion for corrosion-resistant steel and alloys of austenitic class in chloride-containing and highly oxidizing environments in order to deepen and develop a new theoretical perception of their corrosion mechanisms and suggest methods of defining urgently their resistance and corrosion speed in these environments. The methods of research are the ones of measuring mass concentration of Fe, Cr, Ni in fluids using their photocolorimetry, gravimetric method, energy-dispersive analysis, optical miscoscopy, X-ray spectral analysis, metallographic analysis, integral method of determining delta-ferrite. The method of calculating the speed of AISI 304, AISI 321 corrosion-resistant steels and 06XH28MДТ alloy pitting in model backwaters has been developed and implemented into production which gives the possibility to forecast time before perforation of heat exchanging apparatuses' elements in case of their pitting. The method of urgent calculation of AISI 304, AISI 321 corrosion-resistant steels and 06XH28MДТ alloy resistance to intercrystalline corrosion in high oxidizing fluid by GOST 6032-89 has been developed and put into action which allowed to shorten time spent on corrosion resistance calculation from 260 hours to 15 min. AISI 304, AISI 321 steels and 06XH28MДТ alloy are considered optimal due to their pitting-resistance and the speed of pitting growth in chloride containing and their resistance to intercrystalline corrosion in high oxidizing corrosive environment and they are recommended to machine-building enterprises for heat exchanging apparatuses' production. The thesis's main provisions, conclusions and suggestions are used in the practical work of petroleum-refining, chemical, energy enterprises and other branches of industry which apply tanks, vessels, and heat exchanging machines of OJSC "Pavlogradkhimmash", LLC "Ukrspetsmash", CJSC "Asov machine-building plant", OJSC "Severodonetsk plant of chemical non-standard machinery" in their technological processes as well as in trainings at annual seminars held under the guidance of the Board of chief mechanics of the CIS petroleum-refining and petroleum chemical enterprises.