A small, localized hole or perforation in the wall of a pipeline with surface dimensions smaller than 1t or 10 mm whichever is greater in length and width direction. Pinholes are typically the result of corrosionThe deterioration or degradation of a pipeline caused by chemical or electrochemical reactions with its environment. Corrosion is a significant concern as it ca… or erosion, and they can lead to leaks or seepage of fluids from the pipeline.