Dynamics Modeling and Analysis of Small-Diameter Pipeline Inspection Gauge During Passing Through Elbow

Abstract With small diameters, numerous elbows, and complex internal environment, gathering and transportation pipelines are widely applied in the oil and gas pipeline network. To guarantee their safety, the pipeline inspection gauge (PIG) driven by the pressure differential is used. When the PIG collides with the elbows in the pipeline, it exhibits complex nonlinear dynamic behaviors and its reliability and stability may also be greatly affected. To study the vibration response characteristics passing through the elbow, the dynamic modeling of the small-diameter PIG is conducted first in this paper based on the ADAMS software. Then, the fluid–structure coupling is realized by combining the dynamic model and the numerical calculation program of the fluid equation in Simulink. The simulation results indicate that the axial and swing acceleration of the two sections increase as the speed of the double-section PIG increases, while the vertical acceleration decreases. In comparison, it is found that the acceleration response of the second section is often larger than that of the first section. The results also reveal that the axial offset of the PIG at the elbow is inversely proportional to the speed and radius of the elbow, which is the fundamental reason for the lift-off values of sensors.