CORROSION LOOP STUDIES OF PREFERENTIAL WELD CORROSION AND ITS INHIBITION IN CO2 ENVIRONMENTS

摘要

Preferential corrosion of carbon steel weld corrosion and its inhibition were studied by corrosion tests in a flow loop. Eight weld metal/parent metal combination were tested at 60 °C, 1 bar CO2, pH 5-6. Results from 3 selected welds are presented. The tests were carried out in high and low conductivity NaCl brines (0.35 and 35 g/L). It was found that corrosion inhibition could prevent preferential weld corrosion when inhibitor was dosed at sufficiently high concentration. A higher concentration was needed to inhibit the corrosion on some of the weld metals than the parent steel. Furthermore, it was found that too low concentrations of inhibitor could initiate galvanic corrosion of the weld and accelerate preferential corrosion.