How Saltwater Affects Corrosion on Galvanized Steel

Updated April 17, 2017

Galvanised steel is made up of two different kinds of metals to prevent the steel from corroding. Zinc is layered with the steel because zinc will not rust. It is said to be galvanised because the zinc literally becomes a part of the steel, not just layered on top of it like a sealer. Although praised for its use in marine environments, galvanised steel has its limitations in saltwater.

Differing Theories

Galvanised steel used in oceanographic applications has both supporters and protesters. The Brookhaven National Laboratory notes that galvanised steel will rust rapidly in saltwater, necessitating replacement in a few months. However, the American Galvanizers Association states that galvanised steel will last about 12 years in saltwater, depending on placement.

Sea Temperature

Temperature has great effects on the zinc in galvanised steel. Seawater varies in temperature, and problems with galvanised steel can arise when using it in warmer waters near the equator. This is because high temperatures cause zinc to degenerate, which leads to the steel being exposed to saltwater.

Tidal Zone

In the tidal zone, or surface of seawater, zinc can erode from the galvanised steel, exposing the steel to saltwater. This is typically the reason for base steel corrosion.

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About the Author

Specializing in home and garden topics, Nina Stanley begin her freelance career in 2009. She received her Bachelor of Science in horticulture in 2007 from Sam Houston State University and Associate of Science in 2002 from Blinn College. Through her writings, she shares her knowledge of plants with others on various websites.