Technical insights into the long-term integrity and sustainability of China-Russia Eastern Gas Pipeline

This work developed technical insights into the maintenance of integrity, safety and sustainability of the newly operated China-Russia Eastern Gas Pipeline, and beyond. The adverse effect of ground movement in permafrost and semi-permafrost regions, typically frost heave and thaw settlement, on the pipeline structural integrity was analyzed. The pipe beam-soil spring model presently used by industry is not appropriate due to multiple limitations in modelling the pipe-soil interaction (i.e., nonlinearity, conservative assessment of large strain and multiaxial loading, and non-realistic modelling of soil constitutive properties). An integrated technology framework was proposed to quantify the soil stress/strain generated during ground movement. Moreover, the strain ageing of high-strength X80 pipeline steel in the geologically instable region was mechanistically analyzed, where the toughness and crack arrestability of pipe steel, especially the welding zone, would be degraded remarkably. It was suggested that the activation energy for straining ageing and the equivalent ageing time be appropriate for modelling and predicting the strain ageing behavior of X80 steel during the long-term service period in the field. Finally, the state-of-the-arts of the assessment models for mechanical damage, corrosion defects and cracks were reviewed, and the applicability of the modelling methods on high-pressure high-strength steel gas pipelines was discussed. It was recommended that research efforts be made on development of the testing and modelling methods for determination of the toughness and crack arrestability of the steel (especially the weld metal and heat-affected zone), as well as the technology for safety assessment of the target pipeline project.