THE ADVANTAGES OF USING 10X23H18 STEEL INSTEAD OF NICKEL 201 ALLOY FOR MAKING PIPES RESISTANT TO SODIUM HYDROXIDE SOLUTIONS

In oxidizing environments, nickel and its alloys are prone to immunization and therefore the corrosion rate of equipment made of these materials is significantly reduced. Nickel and its alloys are widely used for the manufacture of equipment in contact with alkaline solutions. However, at high temperatures and high alkali flow rates, there is a possibility of contact wear of the metal surface of sodium hydroxide crystals due to the low hardness of nickel. Replacing nickel pipes with ones made of cheaper corrosion-resistant steels would solve the problem of rational design of equipment and pipelines of enterprises associated with the production of sodium hydroxide. The paper presents the results of comparative tests of corrosion resistance of 10X23H18 steel and Nickel 201 alloy in aqueous alkali caustic soda solutions of various concentrations. On a study basis, it can be concluded that the dissolution rate of 10X23H18 steel is significantly less than the dissolution rate of Nickel 201 alloy. It should be noted that with an increase in the concentration of solutions, the corrosion rate of steel gradually decreases, which is not the case for nickel-based alloy. Besides, judging from the results of hardness measurement, 10X23H18 steel can be distinguished due to its high resistance to abrasive wear. According to the scale of corrosion resistance, both materials are absolutely resistant. Since 10X23H18 steel has a lower cost compared to Nickel 201 alloy, it can be recommended substitutionally for the manufacture of the equipment operating in sodium hydroxide solutions at ambient conditions.