A research investigation of "ant nest" corrosion (ANC) on copper tube was conducted in terms of the variables of the corrosion potential and pH value in 10³ ppm copper formate solution over 20 days. The paper presents the surface and cross-sectional observations and examines Cu₂O and H₂O as the stable chemical species produced. A Cannizzaro reaction as a disproportionation reaction from formic acid and a comproportionation reaction from the metallic copper tube and copper formate solution critically influenced the ANC mechanism. The paper also categorizes the ANC attack as a rapid reaction system from the electrochemical point of view by using a polarization resistance curve.
Keywords: comproportionation reaction; copper tube; disproportionation reaction; pitting attack; “ant nest” corrosion (ANC).