Abstract

Pipeline inspection gadgets (PIGs) are routinely used in pipeline maintenance, cleaning, and inspection. A fundamental understanding of the fluid flow around the PIG and consequently its impact on the operation is however still lacking. The surrounding flow and the dynamics of the PIG vary significantly based on the PIG shape and orientation to flow. Previous studies of PIG motion typically employed empirical experimental or reduced numerical data to extrapolate PIG velocities and pressure drops along the pipeline - while this could resolve issues specific to the case being studied, it does not go very far in developing an overall understanding of the dynamics of the system. Our study aims at analyzing a range of configurations for spherical PIGs in a natural gas pipeline to analyze flow patterns around them and determine their impact on PIG motion. Given the nature of the automated launcher analyzed, we carry out U-RANS simulations of a section of the launcher assembly, including the PIG in its initial position, at different field operating conditions. We simulate this setup for both single and multiple PIGs to determine alterations in the flow for a given launch sequence and outline the limitations of the setup. We then use the results from these simulations to determine the optimum configuration for a successful launch.

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