Response analysis of an aerial-crossing gas-transmission pipeline during pigging operations

Pigging operations of natural gas transmission pipelines for cleaning, swabbing and batching inhibition become a regular industry procedure, and that could help to maintain the integrity and optimum efficiency of the pipeline and safeguard both the environment and the assets of the pipeline owner. However, unreasonable controls of pigging parameters including pressure, pig speed, period, etc. may induce harmful vibrations or even structural damage, especially for the aerial crossing segment. In this paper, a dynamic model capable of describing flow characteristics of accumulations driven by pigs and fluid-structure interactions involving fluid pressure, centrifugal force and Coriolis force is established to investigate dynamic behaviors of an aerial crossing pipe during pigging operations. The motion equation is solved using finite element method. Experimental results are used to validate the motion equation of pipes conveying two-phase flow. A lot of numerical simulations of dynamic responses under different boundary conditions and operating parameters are performed, and some interesting and sometimes unexpected results are shown. Finally, the effects of boundary conditions and operating parameters on dynamic characteristics are discussed. This study is helpful for controlling harmful vibration responses of natural gas pipeline under pigging operations and promoting the safety of pigging procedures.