|
Aluminum
Fitting Failure
A cast aluminum alloy "y" fitting used in
firefighting failed during hose pressure testing,
injuring a firefighter. Metallurgical failure
analysis on the failed fitting was to include macro
and microscopic examination, scanning electron
microscopy (SEM), chemical analysis, and hardness
testing.
The casting in question, after apparently at least
27 years of useful service failed in a sudden
manner. The loading causing that sudden failure has
not been determined. No evidence of progressive
fatigue failure was observed. The casting contained
normal cast aluminum alloy flaws, which did not
render the casting defective. The subject casting
did not fail as a result of a manufacturing defect
or because of slow growth crack propagation (metal
fatigue) from a critical sized defect. No indication
of the casting manufacturer was observed, nor was a
year of manufacturing determined.
Photograph A: Overall view of the subject failed “Y” and the three winged “quick connect” coupler.
|
Dr.
R. Craig Jerner, Ph.D., PE specializes in accident
investigation and metallurgical failure analysis,
with 40 years experience as a metallurgical
consultant and accident investigator. He has
testified as a metallurgical expert in over 250
depositions and more than 70 court appearances. If you or someone you know should need the services of Dr. Jerner and J.E.I. Metallurgical, please visit our web site at the buttons below, or e-mail Dr. Jerner --- 