A ball valve mounted on a wellhead failed during an oil field operation. This ball valve failure resulted in a fire and fatality. An overall view of the failed ball valve is shown in Photograph A.
Photograph A Failed oil field ball valve.
A metallurgical failure analysis of the ball valve revealed that very minimal mating between the subject ball keeper threads and the ball valve body threads. This indicated a physical size discrepancy and thus, a defect in cutting the ball valve body threads during manufacturing and therefore was considered a manufacturing defect.