SELECTION OF CORROSION RESISTANT CONSTRUCTION MATERIALS FOR CAUSTIC SODA PRODUCTION EQUIPMENT

P.B. Butorin, Yu.B. Danylov, V.S. Bobrin
Abstract: The manufacture of equipment for the evaporation of sodium alkali at the moment requires a responsible approach to the choice of materials, since the increased aggressiveness of concentrated solutions causes some difficulties during production. The article considers the corrosion resistance of domestic and foreign materials, both the base metal and welded joints in the media of concentration of electrolytic alkalis in the range of NaOH concentrations from 12% to 99.5% and temperatures from 115 to 395о С. For testing, specimens of 20×80 mm in size with transverse welds with two drilled holes were made from the material under study. polished and assembled into cassettes using nickel alloy rods. For the first time, comparative data on the corrosion state of structural materials during evaporation of electrolytic slits obtained by diaphragm electrolysis and electrolysis using a mercury cathode were obtained. The results of corrosion studies are quite well corrected with the experience of operating nickel pipes at the first stage of alkali concentration. The electrochemical heterogeneity of welded joints of alloys 33 and 201 manufactured by “Krupp VDM” was evaluated. The conducted studies of the corrosion resistance of alloys 201 and 33 under conditions of evaporation of NaOH obtained by mercury electrolysis confirmed the high corrosion resistance of nickel alloy 201 at the main stages of alkali concentration. The research results can be used as recommendations for the development of structural materials.
Index terms: corrosion resistance, alloy, caustic, alkali, electrolysis.

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