Effect of Smelt/Gas Interaction on SA-210 Carbon Steel Corrosion, 1998 International Chemical Recovery Conference Proceedings

Coupon tests of SA-210 carbon steel were carried out using a 1% H2S gas environment with or without smelt. Three smelt compositions, with different percentage of Na2CO3, Na2S, were used in the study. Increase in weight loss (25%) was recorded in tests using smelt #1 (80% Na3CO3, 12% Na2SO4, 8% Na2S), while smelt #2 (65% Na2CO3, 15% Na2SO4, 20% Na2S) decreased the weight loss (9%) in 24-hour tests compared to similar tests carried out in 1% H2S gas mixture without smelt. The smelts developed a crust with yellow color. The addition of 1% O2 to the 1% H2S gas environment increased the weight loss of SA-210 carbon steel by 83% and 170% in 4- and 24-hour tests, respectively, compared to similar tests carried out in only 1% H2S gas environment. The addition of 2-4% of NaCl to the smelt, in a 1% O2 + 1% H2S environment, did not significantly change the weight loss. The smelt developed a strong crust with orange color. Whereas, using only NaCl, the weight loss increased by 218%.