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Cold side corrosion

External Appearance:

Corroded and pitted on the cold side of the tube. This usually occurs on the cold side of the tube and is therefore not easily accessed by the inspectors. Lagging and/or seal boxes must be removed to expose some of these potential areas.


Deposit formation may produce corrosion at the interface of the metal and deposit surface. The deposit may trap fly ash, which adds to the bulk of the deposit surface. Fly ash constituents such as iron, vanadium, and sodium may react with sulfur compounds to form highly corrosive, low pH deposits. Wet refractory and leaking flue gas are two possible causes of cold side corrosion. 

Common Locations
Lower and upper dead air spaces
Water walls
Convection pass walls
Extended side walls