To ensure the safe transport of natural gas through steel pipelines, structural integrity must be assessed using fitness-for-service (FFS) methodologies. These assessments (ex. ASME FFS Level 2) require accurate inputs on material properties (particularly toughness), flaw/defect geometry, and loading conditions to evaluate the safety of pipeline networks. Currently, obtaining reliable toughness values is only possible through destructive testing. However, such results are specific to the tested segment or weld and are not applicable to other parts of the pipeline. The ability to estimate toughness in-situ, using non-destructive methods, would significantly improve the accuracy and applicability of FFS assessments across the pipeline network. Research is needed to develop and commercialize methods for non-destructive pipeline toughness estimation, applicable both in-ditch and via inline inspection. This review examines the capabilities and limitations of non-destructive testing methods, identifies technical barriers to their effective use, and assesses the accuracy and applicability of toughness prediction models.