• About NEI • Technical • Products • FAQ • Service • Contacting • Map to NEI • Home • Hot Tips • Nickel Surcharges 2013 • Diagnosing Premature Failures • Resistance Heating Elements • Molybdenum-heating elements • Cold Furnace Start-ups • PDF Brochure (1.9MB)

Diagnosing Premature Failures 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 fracture will show heavy 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. CHECK LIST FOR REPORTING FIELD SERVICE PROBLEMS General Information Required Specific Information Required 1. Customer Name 2. Type of Furnace 3. Furnace Process 4. Element Material 5. Size of Material 6. Miscellaneous 1. Furnace Atmosphere 2. Chamber Temperature 3. Element Temperature 4. Location of Elements 5. Element Service Life 6. Past History 7. Refractory Materials 8. Insulation Conditions 9. External Contaminants 10. Thermocouple Locations 11. Control Equipment Used 12. Work Material Charged Metallurgical Analysis can be performed; Always submit samples of melted element sections with above required information Go to the top of this article Copyright © 1999-2006 - National Element, Inc.