Violent Failure of Super Heater Pendant Tube

Jan. 15, 2013 - PRLog -- David N. French Metallurgists, tube failure specialists are requested to analyze hundreds of metallurgical failures annually. In an effort to raise awareness for their clients as well as provide valuable education of probable failures of specific materials; the profiling of some of the unique failures analyzed have been compiled and available.

The following case profiles a five day old super heater pendant replacement in which a violent failure occurred on the fifth day of operation. The failed tube was significantly deformed from the failure; the rupture was a thick edged blowout in addition there were numerous secondary cracks at the failure site.  

The laboratory proceeded to do their analysis of the failure, a micro taken from the fracture face revealed a thick edged brittle failure; an evidence typical of creep damage. Once viewed under higher magnification creep cracking was discovered as well. After further investigation it was revealed there were no significant signs of the second failure mechanism suspected by the team in the lab (Short term Overheat).

After receiving and reviewing the hardness data it was determined by the metallurgical staff that the tube had not been heat treated post bending. Therefore the tube failure of this new super heater pendant was due to "creep brittle" resulting from lack of heat treatment after bending.

This case study provides valuable justification of how critical proper heat treatment is as well as the inconvenient and costly repair which can result if not performed.

David N. French Metallurgists provide a host of services including but not limited to; Failure Analysis, Basic Boiler Tube Analysis, Life Assessment, Mill Re-certification, Weld Analysis, ID & OD Deposit Analysis, and numerous more. Make sure to browse their website for more information: www.davidnfrench.com