Objective Oil and gas pipelines are critical infrastructure for energy transportation, where long-term operation under complex environmental and loading conditions often leads to various material degradations and failure modes, including corrosion, leakage, coating debonding, and weld or joint defects. Infrared thermography has attracted increasing attention in pipeline nondestructive testing due to its non-contact nature, large-area coverage, and sensitivity to subsurface anomalies. With advances in excitation strategies, imaging modes, and data processing techniques, multimodal infrared thermography has become an important research focus. This review aims to provide a comprehensive overview of the principles, methodologies, and application progress of multimodal infrared thermography for nondestructive evaluation of oil and gas pipelines.

Methods The fundamental theories of thermal radiation and heat transfer relevant to infrared thermography are first summarized. Detection principles of passive and active infrared thermography, including pulsed, lock-in, and laser scanning thermography, are systematically reviewed, together with representative infrared image sequence processing and feature extraction methods. Subsequently, recent applications of infrared thermography in pipeline inspection are surveyed, covering oil and gas leakage monitoring, corrosion and wall-thinning detection, coating and insulation defect evaluation, as well as weld and joint defect inspection. Finally, emerging research trends are analyzed from the perspectives of advanced detection algorithms, intelligent inspection, multi-technology fusion, integrated inspection systems, and standardization.

Results and Discussions Existing studies demonstrate that multimodal infrared thermography can effectively characterize typical defects and failure mechanisms in different pipeline material systems under various inspection scenarios. Advanced signal processing and data-driven methods significantly enhance defect detectability and robustness, while the integration of infrared thermography with other nondestructive testing techniques improves inspection reliability and applicability in complex field environments. However, challenges remain in quantitative defect characterization, environmental adaptability, and the establishment of unified evaluation criteria.

Conclusions Multimodal infrared thermography shows great potential for efficient and reliable nondestructive testing of pipelines. Continued advances in intelligent algorithms, multi-modal data fusion, integrated inspection platforms, and standardized testing protocols are expected to further promote its engineering application and large-scale deployment in pipeline integrity management.