Assuming good furnace construction and use of proper heating element material, most premature burn-outs can be attributed to IMPROPER USE OF THE EQUIPMENT - OR IMPROPER CONTROL OF ITS OPERATION. These enlarged photos should be helpful in "on the spot" diagnosis on common failures.

"Green Rot" Corrosion Symptoms: Green "warty surface. Strongly magnetic. Very Brittle. Will break if bent and green oxide scale extending below surface.

Carburization
Symptoms: Black, dirty surface. Loss of ductility and heat resistance. Internal melting in advanced stages.

Sulfur Attack Symptoms
Extremely "warty" surface - often silvery in color. Strongly magnetic. Extremely brittle

Overheating of Elements

Symptoms: Rough and wrinkled surface. Loss of ductility and deformation of cross-section. Sag caused by internal melting