Failure analysis examination of a titanium condenser tube

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.