What typically causes caustic corrosion in boilers?

Caustic corrosion in boilers is primarily caused by high boiler alkalinity resulting from caustic substances. This type of corrosion occurs when the concentration of alkaline substances, especially sodium hydroxide, becomes elevated within the boiler water. When the boiler operates at high alkalinity levels, and there are localized areas of low pH or insufficient water flow, it can lead to the formation of caustic soda deposits on metal surfaces. These deposits can create a detrimental environment where the protective oxide layer on the metal is disrupted, which then leads to accelerated corrosion of the boiler materials.

Understanding the chemistry involved in boiler operations is essential for effective maintenance and operation. Thus, maintaining the appropriate levels of alkalinity is crucial for preventing caustic corrosion and ensuring the longevity and efficiency of boiler systems. Proper water treatment practices, including regular monitoring and chemical dosing, are necessary to keep the alkalinity within suitable limits and to prevent this type of corrosion.