Caustic soda (NaOH) production is related to a very aggressive environment. The use of special alloys is essential, such as UNS N02200 and duplex UNS S2906 in the first evaporator effect through diaphragm route. A similar environment compared both different materials and concluded that UNS S32906 had performed better than UNS N02200 under boiling 50%NaOH and addition of NaCl and ClO3−. This present study referred to 45%NaOH and 5%NaCl at 141,3°C in the tube side. After six months, UNS S32906 sample was intact while UNS N02200 showed general corrosion attack. It consequently represented a cost-effective solution to implement the duplex stainless steel after several evidence of its equipment life cycle improvement.

Subject
Caustic soda, Materials, Stainless alloys, Corrosion rate, Materials performance, Nickel based alloys, Tubes, Steel coupons, Sodium chloride, Corrosion behavior, Equipment, Sodium hydroxide, Stainless steel
Keywords:
Uns S32906, Uns N02200, caustic soda, duplex stainless steels, corrosion, first effect evaporator
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2023
Association for Materials Protection and Performance (AMPP)
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