What could happen if trapped water beneath scale in a boiler continues to boil?

When water becomes trapped beneath scale in a boiler and continues to boil, it can lead to serious issues such as caustic gouging or under-deposit corrosion. This occurs because the water that is unable to escape can heat up, creating localized high pressure and temperature conditions. The trapped water can also concentrate dissolved substances, causing the formation of caustic environments, which are highly corrosive to metal surfaces.

Additionally, as the boiling continues, the water can create pockets of steam that expand and contract, potentially leading to the mechanical disruption of the scale layer. This disruption contributes to corrosion damage underneath the scale, where the protective oxide layer may be compromised. Overall, the presence of trapped water beneath the scale can create a hazardous environment that accelerates deterioration of the boiler materials, leading to costly repairs and potential failures.

The other options do not accurately describe the consequences of trapped water boiling beneath scale. For example, steam generation may occur, but it does not negate the risk of corrosion. Furthermore, cooling the scale and reducing its buildup would not be an outcome of this situation; instead, the risks associated with trapped water emphasize the need for proper boiler maintenance and scale management to prevent these significant problems.