What causes boilers to corrode around the top?

The correct answer highlights the issue of single metal corrosion, which is primarily caused by the buildup of scale within the boiler. This scaling can create localized areas of high temperature, ultimately leading to the deterioration of the metal around the top of the boiler. When scale forms, it can trap heat and create thermal gradients that significantly weaken the metal, resulting in corrosion.

In properly maintained systems, regular cleaning to remove scale buildup and appropriate water chemistry management are essential to prevent this type of corrosion. The interaction of heat and scale creates an environment where corrosion can initiate, particularly at the top of the boiler where steam and water are in direct contact. Therefore, managing scale is crucial for the longevity and effectiveness of boiler systems.