During routine operation of a gas storage trunkline, localized buckling was observed along a buried segment subjected to cyclic thermal and pressure loading. The buckling event was attributed to accumulated axial compressive stresses exceeding the pipeline’s critical buckling resistance, exacerbated by insufficient lateral support and seasonal ground movement. Initial field inspections identified visible deformations and localized ovality changes, prompting further assessment through in-line inspection (ILI) tool. To evaluate the extent of the buckling impact on structural integrity, a multi-stage assessment was conducted. This included a screening analysis based on DNV-RP-F110 criteria, followed by detailed finite element modeling incorporating actual seabed and route topography data. The analysis confirmed that the pipeline exceeded the critical buckling threshold under certain operational scenarios, particularly during peak load conditions. Mitigation measures were implemented to restore pipeline stability and prevent further buckling. These included localized installation of thrust blocks at high-stress bend locations to resist axial movement, regrading and compaction of backfill material to improve lateral support. The combined engineering assessment and mitigation strategy successfully restored the structural integrity of the gas storage trunkline, ensuring safe and reliable operation under anticipated service conditions. This case highlights the importance of integrating analytical modeling and field inspection.
