Discussion of Beer Bottle Defect

California failure analysis expert witness discusses bottle defects that can affect the bottle strength. In this case there are a string of bubbles in the glass that are mear the surface. There are cases where these bubbles have reached the surface and have opened. This will weaken the bottle by generating  stress risers and thinning the glass locally. Due to hoop stresses, the strength of the bottle is directly proportional to the glass thickness, there are cases where this type of defect can significantly reduce the glass thickness and the bottle strength. This is particularly important in the case of beer and sodas, where the bottle contents are under pressure (54 to 50 psi). In this case the bubbles have not surfaced, thus the effect on the bottle strength is not as severe.

Glass Failure Analysis Of Bottle Defect

California Glass Expert Witness was assigned to determine the cause of failure of wine bottles at the manufacturing facility. During processing the bottles had a higher than normal failure rate. A root cause failure analysis was performed by the glass failure analysis expert witness. He inspected a large number of whole bottles and removed those with visible defects. In addition failure analysis was performed on those bottles that failed in manufacturing. Above left is a photomicrograph of a "crush" or "bruise" found on one of the unbroken bottles. This type of defect was found on several bottles. This bottle defect appears to be a result of impact damage. Curiously, there is an open surface bubble (i.e. seed) in the vacinity of the bruise. Upper right is a photomicrograph of the fracture surface of one of the failed bottles. The origin of this failure is at the same location on the bottle as the bruises found on whole bottles. In addition, this failure started at a small diameter bruise. The repetitive nature of the location and the nature of the defect indicates that this manufacturing defect is caused by the glass handling machinery either at the bottle manufacturing facility or at the bottling plant. Also, this damage is severe enough to cause bottle failure.

Glass Expert Discusses Potential Manufacturing Defect

A manufacturing defect was claimed by a purchaser of a bottle of wine. The bottle defect claim was that there were three pieces of foreign material in the wine. The photograph above shows the food contamination. Two are pieces of glass that appear to match the top of the contaminated bottle. The third piece is the top of the foil for the same brand of wine. The user claims that these pieces were in the bottle before it was opened. This is very unlikely. One of the glass pieces just barely fits through the bottle opening and could not have accidently entered the wine during bottling. In addition, the chances of a foil top being on the manufacturing line are zero. Thus, this "finding" is a hoax. There was no manufacturing defect or bottle defect.