Definition
A classification system that arranges metals according to their electrical potential when in contact with each other in the presence of an electrolyte (such as moisture or salt water). Metals close to each other on the galvanic scale can safely be joined; metals far apart on the scale will cause the more active (anodic) metal to corrode rapidly when they touch in a damp environment.
Plain English
A ranked list of metals that tells you which ones can safely be bolted or riveted together and which combinations will eat each other away when they get wet.
Context Anchor
Seen in aircraft maintenance, corrosion prevention, material selection, and fastener installation discussions.
Derivation
From Luigi Galvani, the 18th-century Italian scientist who discovered that two different metals in contact with a moist conductor produce an electric current. 'Galvanic' refers to that small electrical action between metals, which is what drives the corrosion this grouping is designed to prevent.
Why Pilots Care
Correct grouping prevents hidden corrosion that can weaken airframe components and create safety risks.
Analogy
Think of it like a compatibility chart for metals. Some metals can sit next to each other without much trouble, while others need a barrier between them, especially where water can reach them.
Grounding Statement
If two different metals touch and moisture is present, one metal may start corroding faster than it would by itself.
Intuition Check
Do not confuse galvanic with galvanized. Galvanic grouping is about corrosion risk between different metals; galvanized means coated with zinc for protection.
Example Sentence 1
Before installing the steel bracket on the aluminum skin, the mechanic checked the galvanic grouping to make sure the two metals were compatible.
Example Sentence 2
Following galvanic grouping rules keeps the fuselage free of accelerated corrosion at every metal joint.