Failure Analysis of the Crane Failure at the UF sub 6 - UF sub 4 Expansion Facility

摘要

Cracking of the double strand chain, P/N T-3829, resulted from stress corrosion cracking. The cracks originated from areas of intergranular corrosion located in the center of the pins along the areas where the links are attached. The corrosion present is due to the many corrosive environments the crane has been exposed to over the years. The corrosion is most aggressive in the center of the pin due to entrapment as a result of the links. Pins 2 through 6 failed in shear-face tensile overload as a result of stress corrosion cracking initiating circumferentially around the pin in the region midway through the length of the pin. Pin 1 failed in flat-face tensile overload due to stress corrosion cracking in the same region as pins 2 through 6. Therefore, it is believed that pin 1 was the last to fail. The outer 5 pins were so smeared, that a definite origin could not be determined. However, it is also believed that possibly the missing portion of pin 4 could have failed first, separated the double strand chain inducing a high degree of tensile loading on the rest of the chain, particularly in the area of the chain surrounding pin 4. This tensile loading, along with the high amounts of corrosion present, initiated stress corrosion cracking sites on the various pins, ultimately causing catastrophic failure in tensile overload. (ERA citation 13:043673)