What is the purpose of refractory in boiler construction?

• A. To prevent damage to exterior metal
• B. To absorb heat and radiate it back
• C. To insulate water from the flame
• D. To catalyze fuel combustion

Answer: (A)

Refractory acts as a heat-resistant lining inside the boiler furnace, its main job being to withstand the extreme high temperatures and keep that heat contained within the combustion zone. By lining the interior, it shields the boiler’s exterior metal from thermal damage, cracking, and deformation that can result from direct flame and hot gases. This protection helps maintain the structural integrity of the boiler under firing conditions. While refractory can help reduce heat loss and reflect some radiant heat back into the furnace, it is not used to insulate water from the flame or to catalyze combustion.