Bypass pigging technology in improving pigging safety and efficiency: Principles, progress, and potentials

Abstract

Bypass pigging is a promising strategy to improve pipeline flow assurance by eliminating pigging-generated slugs and reducing pig velocity. This paper provides a comprehensive analysis of the fundamentals, recent progress, and prospects of bypass pigging for enhancing pigging safety and efficiency in gas pipeline systems. A model of bypass pigging motion is developed based on momentum balance, incorporating key factors that affect performance. Recent studies of the influence of the bypass fraction, pressure drop coefficient, and friction force on pigging performance are discussed. The pressure drop coefficient, crucial for accurate dynamic pigging simulation, depends primarily on the pig bypass structure. The impact of variations in the bypass fraction on pig velocity, a significant factor affecting pigging performance, is analyzed. Higher bypass fractions lead to lower pig velocities, resulting in improved pigging efficiency. However, the risk of pig blockage increases owing to the decreased driving gas force at a higher bypass fraction. Therefore, the use of bypass pigs with anti-blocking capability is necessary to enhance overall flow assurance. The paper also highlights the quantifiable benefits of bypass pigging in reducing pig velocity and the pigging-generated slug volume. The prospects for further development of bypass pigging are also discussed. This study aims to comprehensively elucidate the bypass pigging strategy, promoting its wider implementation in natural gas pipelines to enhance pigging efficiency and safety.