Effect of drag-reducing polymers on the rate of flow-induced corrosion of metals

Rates of diffusion-controlled corrosion of copper rotating cylinders in acidified chromate solutions containing Polyox WSR-301 drag-reducing polymer, were measured under turbulent flow conditions. The variables studied were the acid concentration, the cylinder rotational speed and the polymer concentration. The rate of corrosion was found to decrease in the presence of Polyox, depending on the operating conditions. At a given polymer concentration, the maximum inhibition efficiency was found to be a decreasing function of the acid concentration and occurred between a Reynolds number of 4500 and 6000, depending on the acid concentration. The maximum observed corrosion inhibition efficiency was about 23% for an acid concentration of 0.25 M bearing 250 ppm Polyox. Possible practical applications of drag-reducing polymers in operating chemical engineering equipment, to benefit from their dual function as corrosion inhibitors and drag reducers, were highlighted. (C) 1998 Elsevier Science B.V. All rights reserved.