2nd Class Power Engineering 2A2 Practice Exam 2026 - Free Power Engineering Practice Questions and Study Guide

Galvanic corrosion occurs when two dissimilar metals are electrically connected in the presence of an electrolyte, typically water. The primary condition that leads to this type of corrosion is a difference in electrochemical potential between the two metals. This difference creates a galvanic cell where one metal acts as the anode (the one that corrodes) and the other acts as the cathode (which remains protected).

When there is a significant difference in the electrochemical potential of the two metals involved, the more active metal will corrode more rapidly, while the less active metal is protected. This relationship is described by the galvanic series, which ranks metals by their propensity to corrode. The presence of an electrolyte, such as water with ionic content, facilitates the movement of ions, thus allowing the corrosion process to occur.

While factors such as mechanical properties, water presence, and oxygen concentration can influence corrosion processes in general, they do not specifically account for the driving mechanism of galvanic corrosion. Hence, the vital requirement is indeed the difference in electrochemical potential between the two metals in contact.