The present disclosure is related to techniques for the inspection of joints and repairs in pipelines. In this scenario, the a method is provided for the inspection of joints in composite pipes and of composite repairs in metallic pipelines, comprising the steps of (i) emitting a series of acoustic wave pulses, at different frequencies, from a collar of acoustic transducers positioned at a predetermined distance from a joint or repair to be inspected, (ii) recording, in a time interval subsequent to the emission, echoes of wave displacements to the repair or joint in each of the transducers in the form of an A-Scan, and (iii) generating a flattened C-Scan image, through a CSM, for each frequency of pulse emission from the collar of acoustic transducers. The disclosure further provides a system for inspection of joints in composite pipes and of composite repairs in metallic pipelines associated with the provided method.