Assessment of test methods for evaluating effectiveness of corrosion inhibitors in retarding propagation of localised corrosion

Abstract In many service applications an excursion in solution chemistry, temporary loss of inhibitor or increase in temperature may give rise to localised corrosion. It is important to demonstrate that restoration of normal inhibitor levels or use of enhanced doses to restore passivity will be effective in retarding propagation. Accordingly, a number of methods have been explored as a basis for developing a standard test for conducting preliminary laboratory trials. The methods examined were based on galvanostatic pre-pitting, use of the pencil artificial pit, a differential flow system and an artificial crevice arrangement. Of these, the pencil artificial pit was found to provide the most efficient and practical method for evaluating inhibitor performance.