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Bar
Stool Collapse
Metallurgical examination and failure analysis was
requested of a bar stool that collapsed while being
used in a retail location. The person seated on the
bar stool was severely injured. An overall view of
the failed bar stool, with one leg missing is shown
in photograph A.
Photograph A: Overall view of failed bar stool with missing leg.
An overall view of the bottom side of the bar stool
is shown in photograph B. The location of a failed
fillet weld used to connect the bar stool foot ring
to the leg is denoted with a white arrow.
Photograph B: Overall view of bottom side of the subject bar stool. Arrow denotes location of failed fillet weld.
A close-up view of the failed foot ring to leg fillet
weld is shown in photograph C. Note the straight
edge of the fillet (denoted with arrows) weld which
attached the foot ring to the bar stool leg.
Straight edge of failed weld indicates lack of weld
penetration.
Photograph C: Close-up view of failed foot ring to leg fillet weld. Straight edge of weld failure is denoted with arrows.
Underside (side of weld facing bar stool leg) of
failed fillet weld, shown in photograph D, reveals
massive weld porosity. A close-up view is shown in
the Photograph E of the area where the fillet weld
was designed to attach the foot ring to the bar
stool leg. White arrows indicate a heat effect but
total lack of weld penetration.
Photograph D: Close-up view of underside of foot ring to leg fillet weld showing massive weld porosity.
Photograph E: Close-up view of the bar stool leg showing lack of weld penetration.
For reference purposes, a properly and adequately
welded leg to foot ring joint is shown in photograph
F.
Photograph F: Overall view of properly welded leg to foot ring join.
The failure of the subject bar stool was the result
of lack of welding (weld penetration) between the
bar stool ring and the bar stool leg. Massive weld
porosity was a symptom of improper and inadequate
welding.
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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 --- 