On the applicability of the 06KHN28MDT steel to the production of pipes resistant to sodium hydroxide solutions

Sodium hydroxide is a very aggressive medium; therefore, the equipment for its production is subject to intense corrosion. Most of the process pipelines of the Bashkir Soda Company JSC are made of the Nickel 201 alloy, which has low abrasive resistance. As a result, there are cases of equipment failures due to corrosion-erosion destruction. Since this alloy is expensive, it is a relevant problem to replace it with cheaper materials that are not inferior in corrosion resistance. This paper presents the results of studying the possibility of replacing the nickel alloy with the 06KhN28MDT austenitic steel. It is shown that this steel is not inferior in its corrosion resistance and a number of other characteristics to the Nickel 201 alloy. Thus, at room temperature, at a sodium hydroxide concentration of 50%, the corrosion rate of the 06KhN28MDT steel is one-third as high as that of the Nickel 201 alloy. With the increasing concentration of caustic soda, the difference in corrosion resistance between these materials decreases and disappears when it reaches 80%. It has been found that the hardness of the 06KhN28MDT steel is four times as high as that of the Nickel 201 alloy. The studies have proved that the 06KhN28MDT steel can be recommended to replace the expensive nickel alloy in the production of pipes in contact with sodium hydroxide solutions.