Corrosion protection external factors

Corrosion protection refers to a situation in which all the inherent factors to prevent corrosion have been optimized and external intervention is deemed necessary to minimize the corrosion that is beyond the scope of corrosion-preventative factors such as metallurgical, design and life prediction analysis. Corrosion protection can be achieved by (i) addition of inhibitors and (ii) use of protective coatings. 

Corrosion damage is a major factor in ship maintenance and availability. Coatings combined with the impressed current cathodic protection (ICCP) system are the most common means for shipboard corrosion control. They interact with each other to protect the shipboard. Coatings provide primary corrosion protection by isolating the hull metal from seawater, while ICCP systems protect the hull by applying an external source of current to the ship where the paint is damaged or degraded. 

It is believed that formation of exopolysaccharidic substances (EPS) could help the fragile bacteria as a survival technique to protect themselves from external factors that could be life threatening to them [20] and, perhaps, increasing then-capacity to absorb more food by expanding their surface area through the EPS. The role of the EPS material in enhancing corrosion has been emphasised [38]. 

Stress corrosion cracking also involves localized breakdown of the protective film. The corrosion is narrowly confined within the metal due to stress factors which may arise from either residual Internal stress or applied external stress. In some cases the stress failure can be accelerated by chemical factors, such as surface adsorption or hydrogen dissolution from cathodic hydrogen leading to embrittlement. 

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