Method of investigation of local corrosion processes on samples from clad steel

Abstract

The article describes a method developed to evaluate the mechanism of local corrosion processes on the surface of a clad layer of steel specimens, which makes it possible to identify the difference in electrode potentials in artificially created holes. As a result of the study it was found that in a corrosive medium containing Cl- and S2O32- ions, the diffusion of oxidants into a hole of smaller diameter is difficult, which causes a large potential difference between the wall of the hole and its bottom. This process contributes to the development of local electrochemical corrosion.

Cathodic protection of main oil pipeline

“…When the electrode potential is shifted from the optimal range of electrochemical protection -0.85... -1.15 V (by ppm), corrosion processes are significantly promoted. With a decrease in the absolute value of the potential, local corrosion (local, ulcerative) develops, with an increase -peeling of coatings and, as a result, penetration of an aggressive medium into the formed voids [13][14][15][16][17][18][19].…”