FAILURE ANALYSIS EXAMINATION OF A TITANIUM CONDENSER TUBE


11th International Conference on CANDU® Maintenance and Nuclear Components - 2017 Oct. 01-04

Presented at:
11th International Conference on CANDU® Maintenance and Nuclear Components
2017 Oct. 01-04
Location:
Toronto, ON Canada
Session Title:
Material Properties and Degradation

Authors:
P. Delshad Khatibi (Acuren Group Inc.,)
M. Toloui (Chemistry, Metallurgy and Welding Department, Ontario Power Generation)
A. Di ilio (Chemistry, Metallurgy and Welding Department, Ontario Power Generation)
E. Ulvan (Acuren Group Inc.)
  

Abstract

A distinctive form of degradation was observed in condenser tubes made from a commercially pure titanium alloy. Helium leak tests, Eddy Current inspections, and Borescope inspections conducted in the field revealed through wall cracking around the tube circumference in the affected tubes. No indications of embrittlement due to titanium hydrates or defects were found in the microstructure of the failed section and Flattening Test results confirmed the high ductility of the failed tube. Metallurgical failure analysis revealed fatigue cracking at the location of the seam weld that led to tube failure. This was caused by vibration/movement of the tube during service. SEM examination revealed trans-granular cracking and the presence of striations on the opened crack surface of the titanium tube section, which is consistent with fatigue cracking.

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