An Electrochemical Measurement for Evaluating the Cathodic Disbondment of Buried Pipeline Coatings under Cathodic Protection

摘要: Steel pipelines are susceptible to corrosion by the action of corrosive substance in environment and one most common failure modes buried pipeline coating is cathodic disbondment. Consequently, Electrochemical Impedance Spectroscopy (EIS) was used assess effect three important parameters, thickness coating, artificial defect electrolyte type, on disbondment, according ASTM G8. Experiments were done 3.5 % wt NaCl, KCl CaCl2 solutions at room temperature with different thicknesses (354, 483 1014μm) several defects diameters (3, 6 9 mm). Immersion time 28 days during this period, a -1.5 V potential (vs. SCE) applied. Further, EIS measurements Open Circuit Potential (OCP). Investigations showed that thick polyurethane highly resistant disbondment intact areas increases caused decreases rate defects. On other hand, evaluation disputable results, though no logical correlations between defects' any disbonded area individually. In addition, assessment type disbonding might be classified after two parameters: solubility mobility ions. So, dependent cation electrolyte, anion diffusion had less process. Furthermore, comparison cations anions solution disbondments occurred when / 1:1 ratio.