Failure analysis and redesign of the evaporator tubing in a Kimchi refrigerator

A failure analysis was conducted on a pitted aluminum tubes in the evaporator used to cool, a Kimchi refrigerator. The root cause of the failure was a pitting corrosion which was traced to chlorine in a cotton adhesive tape used on the tubes. To reproduce the failure modes and mechanisms causing the tube pitting corrosions, a tailored set of accelerated life tests was applied to the evaporator tubing. Using chemical loads, the key noise parameters in the assembly, including a variety of chemical reaction formula, were analyzed. The failure modes and mechanisms found experimentally were identical to those of the failed sample. To correct the problem, the cotton tape in the cooling evaporator was replaced by a generic transparent tape. The B1 life of the new design is now guaranteed to be over 10 years with a yearly failure rate of 0.1%.