5.1.4 Galvanic Corrosion
Galvanic corrosion is defined as the electrochemical destruction of a metal that results from the current caused by the difference in potential between the metal and another more noble (cathodic) metal when both are in contact with an electrolyte.
Electro Motive Force (EMF)
All metals have a specific electrical potential (the tendency to transfer electrons) when immersed in an electrolyte.
When a steel tank is buried underground the electrolyte is the ground surrounding the steel tank.
The potential is measured against a reference standard. The reference standard that is use is hydrogen, because the EMF for hydrogen = zero (0).
Potential is expressed in volts.
Potential is called the “Electro Motive Force” or EMF.