What condition can arise from high alkalinity in boiler water?

High alkalinity in boiler water can lead to caustic embrittlement, a condition that affects the structural integrity of certain steels used in boiler systems. Caustic embrittlement occurs when sodium hydroxide accumulates in areas where water evaporates, leading to the formation of a highly alkaline environment. This high concentration of hydroxide ions can weaken the metal by promoting the formation of stress concentrations, fissures, or cracks.

The mechanism behind caustic embrittlement primarily relates to the presence of tensile stresses in the boiler materials combined with the extreme alkalinity. This combination can cause the steel to become brittle and potentially fail under operating conditions that may not normally induce failure. In practical terms, this means that operation with excessively alkaline boiler water needs to be closely monitored and controlled to prevent this damaging condition.

Understanding this link is crucial for maintaining the safety and efficiency of a high-pressure boiler system.