Acid dew point temperature and cooling effect cause corrosion. Blade pocket seals protect the blade root and hub surface. The seal closes for the cooling air (sealing air) which passes into the gap between the blade root and hub surface.

In corrosive environments, the blade root part and hub may corrode when the operating temperature is close to the acid dew point temperature. This is because of the cooling effect of sealing air which passes through the gap between the blade root and hub surface. To mitigate this risk, you can install blade pocket seals which ensure a tight fit between the blade root and hub surface.