Failure analysis is possibly the most important skill for a refractories technologist to develop.

For this you need a high degree of scientific integrity. When refractories fail, it is very frequently because someone did something wrong. The operator is normally the person in the best position to know why there was a failure. Since the failure is often his fault, he will try to misdirect you to hide his mistake.

Don’t believe anything he says if he cant prove it. When a furnace fails it is very often caused several compounded errors. When investigating, it is reasonable to assume that everyone is lying about something.

Spend more time looking than listening.

Causes of failure:

1. Melting: The furnace reached a temperature higher that is was designed for.

2. Chemical attack: The refractory was attacked by chemicals which lowered its melting point.

3. Mechanical stresses: this is common in large furnaces.

   1. Rotary kilns – triangles

   2. Ladles complex, related to crunions

   3. Tundishes bulge in middle

4. Thermal stresses: thermal expansion, metals expand more than ceramic.

1. Insulation added outside.