Equipment Door
Failure
A metallurgical failure analysis was requested on a
failed automated equipment door after the door
unexpectedly fell on a worker's arm. The analysis was to
determine whether a design and/or manufacturing defect caused the failure.
The failure was found to have occurred in the aluminum door-header beam.
Visual examination revealed that the header beam failed
in three separate locations: at a large milled notch in
the center, and at both header beam ends.
Microscopic and macroscopic examination further revealed that
the beam failed due to progressive overload. Design
analysis showed that the door was safe under normal
usage conditions. Reconstruction of the incident was
attempted through building and testing an exact copy of the
door. Mechanical and metallurgical testing of the
replica door showed that the door functioned safely if
properly maintained. The three distinct and
separate failures in the
header beam prior to the actual door accident attest to
the fact that the header beam failure was not due to improper design
or manufacture.
The final result of the metallurgical failure analysis
was that improper maintenance was the cause of this
failure. Loose
bolts and improper maintenance by the operator caused the
door failure.
Photograph A: Overall view of replica
door positioned for testing
Photograph B:
Cracked beam in center
of automated door header.
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Dr.
R. Craig Jerner, Ph.D., PE specializes in accident
investigation and metallurgical failure analysis,
with over 30 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 --- 