There are many advantages in hot dip galvanizing steel components which will be exposed to the atmosphere or hostile environment.

Corrosion Resistance - 
Long Life

As soon as the galvanized part leaves the zinc bath the surface is immediately attacked by the oxygen in the air to form a very thin film of zinc oxide which is impervious and has excellent adhesion, giving added corrosion resistance and protection to the zinc coating.

Edge and Corner Protection

Hot dip galvanizing coatings are thicker than plastic dipped or painted coatings on sharp corners.

Economy

Hot dip galvanizing has a low initial cost and combined with long life gives a very economical protection of steel for long periods. It is not unusual for zinc coated steel components to last for more than twenty years in hostile environments.

Paint Coating

The steel rusts where the paint film has been damaged. Rust creeps under the paint film, which is lifted up from the steel surface. Corrosion continues until the damage has been repaired.

Coating of more Electro-Positive Metals Than Steel

-e.g. nickel, chromium and copper - give rise to more rapid corrosion at the point of damage than if the steel had been uncoated. The corrosion often takes the form of pitting, which can even go through the steel.