Corrosion of Mild Steel In 40 Percent Sodium Hydroxide Solution at 316 C

Measurements of corrosion rate of mild steel in 40 percent sodium hydroxide solution at 316 C were correlated with microscopic examinations. Thick films of adherent magnetite were formed. Severe pitting attack occurred beneath the magnetite, perforating a 0.030 inch steel wall within 130 hours. Topography of the pits was similar to that described as typical of pitting in high pressure boilers. Mechanism of this attack is discussed. 6.2.3, 4.3.3, 3.2.2