www.saVRee.com Deaerators Explained| pg. 3
corrosion) is an example of localised corrosion. Oxygen pitting often occurs wherever the
water and steam phases meet (waterline in boiler or deaerator), or under sediment that
has settled somewhere in the system.
Stress corrosion occurs in high stress point areas. High chloride levels, thermal shock
and high pH, can all cause stress corrosion. Stress corrosion caused by high pH levels is
referred to as caustic embrittlement. Stress corrosion caused by thermal shock is
referred to as fatigue corrosion.
Deaerator System
Boilers generate steam which is delivered to the process. Some of the steam transfers its
energy to the process and condenses; the resultant water is termed condensate.
Condensate is gathered throughout the steam system and is returned to a central storage
tank, this is either an atmospheric feedwater tank, or a pressurised feedwater tank
(deaerator).
Spray Deaerator
Makeup water replaces water losses within the system. Water losses may be an
unavoidable part of the process e.g. steam cleaning of glass bottles in the edible food
industry, or, may be due to leaks or evaporation losses etc.
When condensate reaches the feedwater tank, it is termed feedwater, as it is then fed to
the boiler. Similarly, when makeup water enters the feedwater tank, it is thereafter
termed feedwater.