Stray-Current Corrosion

Stray-current corrosion is an attack of a metal due to the formation of an electric current through that metal which is unintended. This corrosion form is independent of environmental conditions. A direct current is more damaging than alternating currents. In alternating currents, damage will decrease as frequency increases. A major source of stray-currents is underground power lines. Damage to active-passive metals such as aluminum alloys and stainless steels is greater than that for active metals.

Managing Stray-Current Corrosion

The best way to combat stray-current corrosion is to prevent the current using insulation techniques. Coatings will not protect the metal and may even accelerate the attack if a flaw in the coating exists. If the current cannot be prevented, methods to deter corrosion include the following:

• Grounding the Stray Current
• Sacrificial Anodes
• Insulation