What must be present for caustic embrittlement to occur?

Caustic embrittlement is a specific type of damage that occurs in metals, particularly steel, which is utilized in boiler tubes and other high-temperature environments. The condition arises when a combination of stress on the metal, leakage of boiler water, and an increased concentration of caustic substances, typically sodium hydroxide (NaOH), is present.

Under conditions where boiler water leaks can mix with higher concentrations of caustic, it leads to localized weakening of the metal structure. The high concentration of caustic can promote a reaction that leads to the embrittlement process, which is particularly dangerous as it can severely compromise the integrity of boiler components. The stress on the metal exacerbates the issue, making it more susceptible to cracking and failure.

In contrast, while high levels of chlorides, heat, pressure, or excessive steam production are relevant factors in various corrosion or failure mechanisms in boilers, they do not directly result in caustic embrittlement. Understanding the specific conditions that facilitate caustic embrittlement is crucial for preventive measures in managing boiler operations and maintenance effectively.