What does "thermal shock" refer to in boiler maintenance?

"Thermal shock" refers specifically to the stress that occurs in materials, such as those found in a boiler, due to sudden and significant changes in temperature. When a component of the boiler experiences a rapid increase or decrease in temperature, it can cause uneven expansion or contraction. This phenomenon can lead to cracking, warping, or other kinds of damage to the structural integrity of the boiler components.

Understanding thermal shock is crucial for boiler maintenance because managing temperature changes and ensuring gradual heating or cooling can help prevent these harmful stresses from occurring. Proper operating procedures and controls are essential to minimize the risk of thermal shock, thus preserving the functionality and safety of the boiler system.

Other options do not accurately capture the critical concept of thermal shock; slow cooling, pressure fluctuations, and sediment buildup involve different mechanisms and maintenance issues that do not relate directly to the stress caused by sudden temperature changes.