How hot-dip galvanizing actually resists corrosion

Hot-dip galvanizing submerges cleaned steel in molten zinc, forming a metallurgically bonded layer rather than a painted-on coating — which is why it doesn't chip or peel the way surface coatings can.

Zinc also protects sacrificially: even where a scratch exposes bare steel, the surrounding zinc corrodes preferentially and keeps protecting the steel underneath.

This is why GI pipe consistently outlasts painted MS pipe in outdoor and wet applications, even though the base steel is identical.

Coating thickness is measured and specified separately from the pipe's dimensions, typically in grams of zinc per square meter. A higher coating weight costs a little more but extends service life meaningfully in coastal or industrial atmospheres where corrosion is faster.