Identifying and describing metal loss defects in pipe walls is an indispensable task in transporting operations, this abnormal condition mainly appears as a result of corrosion and gouging. These metal losses can lead the pipeline to unsafe conditions originating leaks, rupture of the structure and associated hazards. In this work is presented a comparative study to assess the capabilities of detecting and describing the metal loss in a pipe wall based on three non-destructive techniques: Magnetic Flux Leakage, Eddy Current Testing, and Guided Waves. These are compared by revising their physical principle and presenting a brief review of results obtained in metal loss inspection by considering some criteria as its sensitivity, depth of penetration, the range of inspection, and implementation easiness. Finally, the discussion is focused on of establishing which technique is most adequate for the inspection according to some characteristics of the metal loss defect.