Stress analysis and design optimization for inlet/outlet lines in pigging stations: A case study of Trans-Asia Gas Pipeline

To ensure safety of large-diameter, high-pressure inlet/outlet lines without anchor blocks, the Trans-Asia Gas Pipeline is taken as an example to discuss on design of inlet/outlet lines in pigging stations based on flexible arrangement and stress analysis. In this study, pipeline stress, displacement, external forces and operational factors are considered. Simulation calculation and analysis are performed for installation of anchor blocks and flexible installation of pipelines by using Caesar II, the software for analysis of pipeline stress. The results show that conventional anchor block installation processes for large-diameter high-pressure trunk pipelines may involve theoretical thrust of pipeline on anchor blocks up to thousands of tons. Such a huge thrust may require anchor blocks with large size and huge investment. In addition, the thrust may be permanently maintained between the pipeline and anchor blocks, leaving significant threats to operation safety of the pipeline. Alternatively, in case of flexible installation, displacement and deformation of pigging elbows with relatively large radius of curvature can effectively minimize thrusts required and reduce investment accordingly. This design, without anchor blocks, can ensure operation safety within the full life cycle of the pipeline.