What is one of the corrosion risks associated with air in steam lines?

The presence of air in steam lines significantly increases the risk of corrosion primarily due to the formation of carbonic acid when carbon dioxide (CO2) dissolves in water. This can occur because steam carries small amounts of CO2, which can come from the degradation of organic materials or from the combustion processes linked to boiler operation.

When water and carbon dioxide coexist, they can react to form carbonic acid, a weak acid that can still lead to corrosion in the presence of moisture. This acid can attack the metal surfaces within the steam lines, particularly mild steel, leading to general corrosion, which reduces the lifespan of the equipment. This type of corrosion is especially risky in areas where water might collect or condense since acidic conditions will be maximized in those locations.

Understanding this mechanism highlights the importance of maintaining proper water quality and ensuring that there is minimal air or CO2 presence in steam systems to mitigate corrosion risks effectively. This emphasizes the need for proper treatment of make-up water for boilers and the implementation of oxygen scavengers to remove free oxygen, ensuring the integrity of the steam line infrastructure.