Effect of ferrous sulfate treatment on microbially influenced corrosion of CuNi 70/30 marine pipeline alloy by sulfate reducing bacteria†

Abstract

This study investigates the effect of ferrous sulfate (FeSO₄) treatment on protective film formation and subsequent microbially influenced corrosion (MIC) of CuNi 70/30 pipeline alloy, a material commonly used in maritime platforms. CuNi 70/30 coupons were treated with FeSO₄ solution in potable water and seawater simulating a flow speed of 0.94 m s⁻¹ for 5 d. The treated coupons exhibited a protective iron oxyhydroxide, likely lepidocrocite (γ FeOOH), film on the surface. MIC performance was evaluated in modified Baar's medium with SRB for 28 d. Results revealed thicker SRB biofilm and increased MIC pitting attack on FeSO₄ treated coupons compared to untreated coupons. These findings suggest that FeSO₄ treatment may exacerbate MIC susceptibility in MIC-prone environments, highlighting the importance of carefully considering corrosion mitigation strategies in maritime platform applications.