What is caustic embrittlement in relation to boilers?

Caustic embrittlement is a specific type of corrosion that occurs in steam boilers, particularly at high temperatures and pressures, due to the presence of high alkaline substances, such as sodium hydroxide (caustic soda). This condition typically arises when the boiler water has an excessive concentration of these alkaline elements, leading to the formation of caustic deposits on the internal surfaces of the boiler.

When the water evaporates, it can create a concentrated caustic solution in areas where the fluid motion is limited, such as in welds or in the presence of deposits. This concentrated caustic can then lead to stress corrosion cracking of various materials, especially low-carbon steel, which is common in boiler construction.

Understanding that caustic embrittlement is primarily linked to high alkaline conditions helps you to identify and mitigate potential risks in boiler operations. By controlling the water chemistry, particularly the pH level and concentration of alkaline chemicals, the likelihood of caustic embrittlement can be significantly reduced, ensuring the integrity and safety of the boiler system.