A method, apparatus and system for locating external apparatus mounted to a tubular in a wellbore. The identification of apparatus, such as cable clamps, enables other tools in the string to operate more precisely. A computer model is used to locate the apparatus from acoustic images, which images are acquired using a downhole device having an acoustic sensor or acoustic array. The model may be a classifier, which may be machine trained to classify whether an apparatus is present, its location and its orientation. Automating this locating enables very long wellbores to be processed quickly.