Simulating calculation on maximum allowable displacement of the free end of pipeline based on butt welding

Due to the corrosive perforation and third-party damage, multiple leakage accidents occurred to the long-distance oil and gas pipelines, for which on-site emergency repair was required, and further pipeline alignment should be performed before welding. For this reason, a series of pipelines with different steel grades, different pipe diameters and different wall thicknesses were taken as the research object, and in order to meet the requirements of the emergency repair operations of long-distance gas pipelines such as alignment for pipeline displacement, the pipe-soil coupling effect was considered according to the structural characteristics of the long-distance pipelines and the mechanical characteristics of the soil around the pipeline. Besides, deformation simulation and stress analysis were conducted for the buried pipelines with D-P model, and the maximum allowable displacement of the free end of pipelines in different excavation lengths of various series of pipelines was solved. The results show that the maximum allowable displacement of the free end of pipelines is jointly affected by the pipe diameter, wall thickness and steel grade. Definitely, it is positively correlated with the excavation length and the wall thickness, but negatively correlated with the pipe diameter. Generally, the calculation results can provide a theoretical reference for the pipeline excavation length during emergency repair operations.