Is Thicker Always Better? The Truth About Galvanized Steel Pipe Coating Thickness

It’s a common belief that the thicker the zinc coating, the better the protection on galvanized steel pipe. While this is partially true, the full story is more nuanced — and understanding the right balance is key to performance and cost-effectiveness.

Thicker Coating = Better Corrosion Resistance?

Yes — up to a point. A thicker zinc layer offers longer-lasting protection against rust, especially in coastal, industrial, or highly humid environments. For example, pipes with 100μm+ coating thickness may last over 25 years outdoors without major degradation.

But... More Is Not Always Better

Excessive coating thickness can cause issues. Too much zinc may lead to:

Surface roughness, affecting appearance or fluid flow
Welding difficulties, requiring additional surface treatment
Increased weight and cost, which may not be necessary in mild environments

What’s the Optimal Thickness?

Standards like ASTM A123 or ISO 1461 recommend specific coating thicknesses based on the application. For most structural and general-use pipes, a coating between 55–85μm offers a strong balance between protection and practicality.

Thicker isn’t always better — smarter is better. Choose coating thickness based on where and how the galvanized steel pipe will be used. That way, you get maximum performance without unnecessary cost or complications.