What should you use during the abrasive process to prevent flash rusting?

• A. Sodium Chloride MIL-S-24521
• B. Sodium Nitrite MIL-S-24521
• C. Calcium Chloride MIL-S-24521
• D. Potassium Nitrite MIL-S-24521

Answer: (B)

When steel is freshly abraded, moisture on the surface can cause flash rust before a coating is applied. To stop that rapid rusting, a corrosion inhibitor is added to the process fluid or rinse. Sodium nitrite is a well-established inhibitor for ferrous metals in aqueous environments because it helps form a protective passivating layer and shifts the electrochemical conditions to slow down oxidation. That protective action prevents the quick, surface-level rust that would otherwise appear after blasting. MIL-S-24521 specifies sodium nitrite for this purpose, making it the best choice to prevent flash rusting during the abrasive process. The other options either introduce chloride ions that can promote corrosion or lack the effective nitrite-based passivation action called for in the standard.