Corrosion attacks fans through humid air, condensation inside the casing during shutdowns, and corrosive components in the gas stream. Left unchecked it thins the impeller — which causes imbalance and eventual failure — and weakens the casing. The defence starts with matching the material to the duty: standard carbon steel for clean, dry air, and stainless 304 or 316L where moisture or corrosives are present.
Where a full stainless build is not justified, anti-corrosion coatings and good drainage of the casing protect the fan at lower cost. Allowing the fan to run briefly before a long shutdown drives off internal moisture and helps prevent standstill corrosion. Tell us the gas composition and humidity and we will recommend the material and coating that balance cost against service life.