Bricks, roof tiles, vitrified clay pipes, and sanitary wares are all ceramic products that need to be fired at a high temperature to get their robust characteristics. Tunnel kilns are the apparatus in which such firing often takes place.

Tunnel kilns can be described as a rectangular chamber with a height of more than 3 meters, width of almost 2 meters, and length of more than 100 meters. The temperatures in the tunnel kiln can reach more than 1,000°C, depending on the product being fired.