Abstract
The protection effectiveness of commercially available vapor phase corrosion inhibitors was evaluated on their Inhibition of the Above Ground Storage Tanks (AST) bottoms. Optical microscopy post vapor-inhibiting ability (VIA) corrosion tests revealed that these inhibitors have significant influence on the degree of protection and stabilization of the protective passive film. These inhibitors showed a corrosion rating better than grade 3 (excellent corrosion protection) and more than significant decrease of the corrosion rate. Surface coverage was improved due to the increase of effective surface area and the increased partial pressure of vapor inhibitors as powder particle size reduced. Electrochemical Impedance Spectroscopy analysis showed that these inhibitors increase the polarization resistance significantly and provide a very stable low corrosion rate. These improvement in passivity and stability of the film on the steel surface is very critical, as the API 653 inspection interval period is very long and detection of any localized pitting corrosion in timely manner to avoid any catastrophic disaster and leaking of toxic substance to surroundings is hard to achieve.
