What Does
Galvanic-Induced Failure Mean?
Galvanic-induced failure is corrosion damage or failure induced by galvanic coupling.
This is an aggressive and localized form of corrosion due to electrochemical reactions often found between two or more dissimilar metals in an electrically conductive environment. It is usually associated with black steel anodes and brass or copper cathodes.
In this type of failure, a metal with a lower electrochemical potential is the cathode in a connection and remains unchanged. A metal with a higher potential is the anode and corrodes.
Galvanic-induced failure is also known as galvanic corrosion.
Corrosionpedia Explains Galvanic-Induced Failure
Galvanic-induced failure can occur when different metals are joined together, and are greatly dependent on existing corrosion conditions and the piping system involved. It is more frequent in open condenser water and process water systems than chilled water or fire protection systems. It is most prevalent where corrosion activity is already high, and can produce widespread failures and total pipe separations. A connection in piping systems between copper and low-carbon steel results in steel corroding many times faster than steel alone.
This type of failure commonly occurs between carbon steel pipes joined to a brass valve, with the most serious examples found at galvanized steel-to-brass valve connections. A bluish-green deposit at the valve and lack of leakage at its opposite steel-to-steel connection provides confirmation that a galvanic condition exists.
Connecting pipes of various materials causes difference in electrode potential, leading to galvanic corrosion and serious damage of pipes, valves and other equipment in the system. Systems deteriorate particularly quickly in cases such as:
- Water with free ions (like seawater)
- Acids or bases
- High temperatures
- Elevated oxygen