Pipelines are vital infrastructure for the transportation of water, sewage, oil, and gas because they offer a better safety option and fit into the minimum environmental hazardous than other modes. But pipelines are aging and getting damaged all the time, which can lead to significant loss of resources and contamination of the environment. Regular maintenance and inspections are necessary for pipelines to operate efficiently and prevent overspending. This paper reviews the core techniques used in each of the four missions—localization, mapping, navigation, and inspection—that these robots have completed. Additionally, because image processing has become a widely used and crucial strategy for completing all of the aforementioned missions, we made the decision to review the thorough classification of techniques for image processing in a separate section.