Pitting and channeling of boiler metal in the water are caused by what?

Pitting and channeling of boiler metal in the presence of water are primarily caused by the presence of dissolved gases, notably oxygen and carbon dioxide. These gases can lead to corrosion, which is a critical issue in boiler systems. When oxygen enters the water within the boiler, it reacts with the metal, leading to localized corrosion pits. Similarly, carbon dioxide can dissolve in water to form carbonic acid, which further accelerates the corrosion process.

Inadequate management of water chemistry, including the control of oxygen and carbon dioxide levels, is essential in preventing such deterioration of boiler metal. Regular monitoring and treatment of the boiler feedwater can significantly reduce the risk of pitting and channeling by mitigating the corrosive effects of these gases. Therefore, understanding the role that dissolved gases play in the corrosion mechanisms is crucial for maintaining the integrity and longevity of boiler systems.