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 CRANES
CASE CN1 - Floating Cranes; Free-Fall Restraint, P. Malone
Problem: Dropping a torpedo while transferring from one area to another using
a 60 ton floating crane which could have resulted in great loss of lives as
well as equipment.
Symptom: While using 60 ton floating crane to off-load torpedoes, the crane
operator lost control of the load dropping it onto a barge.
Collection of Facts: Review of the original crane's design revealed that the
crane was designed so the load could be lowered in a free fall condition. The
operation procedures provided a method to prevent such an occurrence; however,
this procedure was not always followed by crane operators. The history of
accidents with this model crane indicated that a number of similar accidents
had also occurred.
Solution: Design and install modification that prevented the operator from
using the free fall capability design of the floating crane.
CASE CN2 - Non-destructive Testing of Crane Hooks, P. Malone and Don Potter
Problem: The requirement for annual disassembly and nondestructive
examination of crane hooks was questioned by end users.
Symptom: The end user (Naval Shipyards) felt that it was not a cost effective
method of insuring crane safety and that NAVFAC should do something to provide
a more cost effective method for accomplishing this requirement.
Collection of Facts: The history of crane accidents was reviewed and it
indicated that the only accidents involving hook failure were due to gross
over-loads. An engineering investigation project was conducted to study the
effect of crack location and fatigue on hook failure.
Solution: The results of the Engineering Investigation indicated that the
critical area for hook failure could be examined while the hook was on the
crane.
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