Carbon Dioxide in Boiler Water

Carbon Dioxide is a constituent of air.  As such it get dissolved in water.  Carbondioxide mixes with steam to form carbonic acid.  Carbonic acid is an unstable compound.  It has a tendency to react with steel and can thus corrode piping.

Another way carbon is present in the water is in the form of bicarbonates.  These carbonates decompose in the boiler to produce carbon dioxide.   This carbon dioxide is usually present in the condensate. 

Carbon dioxide reduces the pH of the water.  This turns the water acidic which results in further corrosion. 

Hence, carbon dioxide has to be removed from the water.  One simple way of removing carbondioxide is by heating the water.  Heating the water reduces the solubility and thus removes the gas.  The water should be externally treated to remove the carbonates. 

Venting at specific locations of condensation can also reduce the carbon dioxide in the system.