Spalling in a boiler occurs in which area?

• A. Superheater
• B. Combustion Chamber
• C. Economizer
• D. Final Stage of Furnace

Answer: (B)

Spalling happens when the refractory lining cracks and flakes away under intense thermal stress. The area where this is most likely is the combustion chamber because it is the hottest part of the boiler and undergoes rapid, extreme temperature changes from the flame and hot gases. Those rapid heat-up and cool-down cycles, combined with potential moisture in the brickwork, cause the refractory to crack and spall, exposing the cooler core and reducing insulation. Downstream areas like the economizer operate at lower, more steady temperatures and stresses, so spalling is not as common there. The final stage of the furnace is still subject to heat, but the direct, severe thermal conditions that drive spalling are centered in the combustion chamber.