Yes, galvanized steel does corrode. In fact, there are a million steel transmission structures fighting corrosion issues in North America and nearly 20 percent of the world’s steel production supports replacing steel structures and equipment that has been damaged by corrosion.
The Corrosion Process for Galvanized Steel
In the U.S., the galvanizing process can provide roughly 30-40 years of corrosion resistance, depending on the environment. At that point, the zinc carbonate begins to break down into varying levels of corrosion. Once corrosion starts, it accelerates rapidly. At this time, painting is an effective way to reduce corrosion and/or slow down the corrosion process.
- New galvanized steel has a pure film of zinc on the substrate.
- Almost immediately, that zinc oxidizes, becoming zinc oxide.
- Then, once humidity or any moisture is introduced, the zinc oxide converts to zinc hydroxide.
- After approximately 12 to 18 months, a zinc carbonate forms, which provides a barrier coating that protects the steel. Zinc carbonate can be painted but doesn’t necessarily need to be.
- Approximately 30-40 years later, the zinc carbonate begins to break down and the corrosion process begins.
- Once the galvanized layer wears away, from a high level of zinc to increasingly iron and zinc, orange, brown and yellow staining will begin to appear. This is a sign that not much of the zinc remains.
- Once the zinc is depleted, you are dealing with the metal structure that has essentially no galvanizing remaining. At this point, the corrosion rate will skyrocket! You may see a structure that has looked perfect for 30 years deteriorate in less than 10 years to solid rust.
This is when Induron can offer a solution for extending the useful life of galvanized T&D structures.
Extreme Asset Protection
At Induron, we provide complete end-to-end support for our coatings and partners. From the original coating project to ongoing maintenance and service, your success, satisfaction, and reputation are our highest priority.
The Induron approach to asset protection is the lowest applied cost per square foot per year, and we can calculate the cost based on experience and proven results. All in all, you can count on us for extreme asset protection.