CASE PS3 - Failure of Barbed Tape Obstacle, J. Cecilio
Failure of Barbed Tape Obstacle from SWEF PACSUB Base, Bangor
Collection Of Facts: The perimeter fence at the main limited area and
remote magazine area approximately 1,800 feet in length. There was over
400 breaks in the barbed tape in the main limited area. All the breaks
occurred in the inner coil.
The installation uses a dual coil of 30/24 barbed tape fastened between
the "Y" Outriggers on a chain link fence. Breaking and failure of the
stainless steel barbed tape fence topping has occurred at several other
sites where high winds have been encountered. Corrosion and pitting of
the stainless steel has also been observed where the material was
installed in a marine atmosphere.
Laboratory analysis has indicated that failure appeared to be caused by
fatigue in the defamed areas in the barbed tape. Stress concentration
was set up in the deformed area due to crimping and cracks were initiated
in this area when the tape was subjected to service load induced by winds,
temperature and vibration. In addition, improper installation and
fastening of the barbed tape to the fence structures was reported to have
caused excessive flexing and movement resulting in acceleration of the
fatigue and breakage. The black plastic strapping has also been found to
deteriorate and break, which then leads to excessive movement and flexing
of the barbed tape under wind conditions.
Solution: Based on the above problem, type specification was modified.
Plastic strapping was replaced with steel wire rope. Formalize and
provide installation procedures for the barbed tape fence topping.
Specify types of stainless steel and manufacturing procedures to insure a
more uniform product with better fatigue and corrosion resistance.