Stress Corrosion Cracks (SCC) are among the defects in pipelines that are least understood and most difficult to detect, but which have accounted for some of the severest ruptures in pipelines throughout the world. Pipetronix has developed a new generation of internal inspection device for detecting SCC and other cracks and crack-like defects in pipelines, the UltraScan CD. It is a completely autonomous device that travels through the pipeline, carried by the fluid, uniformly scanning the pipe wall for defects with full circumferential coverage and for lengths of several hundreds of km. The information is processed on-line to allow for storage of huge amounts of data to be processed when the tool is retrieved from the pipeline. The UltraScan CD has, up to now, successfully inspected more than 1,000 km of oil and gas pipelines. Comparison of the findings with corresponding verifications from excavations illustrate the sensitivity and reliability of the inspection method and its ability to discriminate between different types of defects found in the pipelines.