Dynamic characteristics of the pipeline inspection gauge under girth weld excitation in submarine pipeline

Abstract

Pipeline inner inspection technology based on Pipeline Inspection Gauge (PIG), is the primary means for ensuring the safety of submarine pipelines. The dynamic characteristics of a PIG can change abruptly with the excitation of obstacles such as girth welds inside the pipeline, which would result in failure or inaccuracy of the inspection results. This study establishes a dynamic model of the PIG sealing disc based on Kelvin spring damping in the circumferentially confined space. The axial vibration differential equations of the PIG is examined in detail. MSC/ADAMS is used to conduct the dynamic simulation of the PIG at different motion velocities and center of mass positions while passing through the girth weld process. Results indicate that the axial vibration caused by the girth weld intensifies substantially as the speed of the PIG increases, while the pitch and vertical vibrations exhibit a significant decline with an increase in the motion velocity. The change in the PIG’s center of mass positions has little effect on its axial vibration, while the pitch and vertical vibration conditions are significantly different in the same circumstances.