2004 Volume 53 Issue 9 Pages 440-445
Wall thinning to the inside surfaces of T's, elbows and straight tubes which were located at just downstream of elbows occurred, when a 1% CuCl2 (II) solution was allowed to flow through a pure copper piping with a nominal dimension of 15A at the flow velocity of 1-2m/s. Flow velocity difference corrosion was presumed to be the cause of the damage, since it occurred at the surface of inner curvature of the elbow where the flow velocity was lower than that at the outer curvature. This assumption was proved to be valid, as evidenced by measurement of the macro cell current which was directed from the higher flow velocity area to the lower velocity area, as well by the polarization behavior of these areas. Based on the corrosion mechanism, preventative action was taken, resulting in a reduction in wall thinning of the inner curvature surface of the elbow down to the level of that at outer curvature surface of higher velocity area. Finally, the issue of how closely the 1% CuCl2 accelerating test solution simulated the corrosion of pure copper piping in a system that carries brine or tap water was discussed.
