Journal of Failure Analysis and Prevention

, Volume 5, Issue 4, pp 14–19 | Cite as

Failure analysis of a high-temperature thermocouple

  • K. Gates
  • S. Benhaddad
Case Histories


A solid oxide fuel cell unit operates at high temperatures of 700 to 800°C. The operation of the unit is controlled by a set of instrumentation including sensors, thermocouples, and voltage leads. Two S-thermocouples were inserted in the after-burner where temperature is constantly at 1000°C. During operation of one prototype unit and after 1000 h, the thermocouples started to give erratic readings and led to complete shutdown of the unit. Analysis of the thermocouples revealed a series of events may have occurred due to stress induced by the design, materials and operating conditions, contamination during manufacturing, or a reducing environment caused by sheathing. The specification from S-type to B-type may remove the risk of reoccurrence. A design change in platinum burner thermocouples to ensure an oxygen-rich environment for the platinum was also recommended.


catastrophic failure contamination failure analysis high temperature materials selection metallurgical investigation nonferrous metals 


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Copyright information

© ASM International 2005

Authors and Affiliations

  • K. Gates
    • 1
  • S. Benhaddad
    • 2
  1. 1.Thermex Metal TreatingEdmontonCanada
  2. 2.Versa Power SystemsCalgaryCanada

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