Caustic corrosion in boilers is typically a result of which type of contamination?

Caustic corrosion in boilers is most commonly associated with alkalinity that arises from contaminated water supplies. Shore water contamination refers to water that might carry various impurities, including dissolved minerals and other substances, which can increase the alkalinity of the boiler water. When such water is present, it can lead to a phenomenon known as caustic embrittlement, where the presence of sodium hydroxide (or other caustic materials) can corrode boiler metal by creating local concentrations of caustics under conditions of high temperature and pressure.

This process occurs because the contaminants can significantly alter the water chemistry within the boiler, promoting conditions that are conducive to caustic attack. The increased pH from such contaminants can lead to significant metal loss in the areas of the boiler system that experience concentrated caustics, especially in areas of high heat and low flow.

In contrast, oil contamination can lead to other issues, like fouling or reduced heat transfer. Acidic contamination typically results in acid corrosion, which operates under a different mechanism than caustic corrosion. Chemical treatment contaminants can also impact the boiler system but are usually designed to prevent rather than cause corrosion. Therefore, the primary link between caustic corrosion and contamination in this context is indeed the increased