Model and influential laws on the self-excited vibration of pigs for natural gas pipelines

In the process of pigging, the cup of the pig will suffer greater vibration and even deformation under the joint effect of the impurities accumulated at the front end of the pig and the friction on inner wall of the pipeline, and thereby the effectiveness of the pigging operation is reduced.In this paper, the nonlinear change laws of friction between pig cup and pipeline inner wall were described based on LuGre model and Stribeck curve.Then, the pig self-excitation model characterized by the lumped mass elastic micro-body was established by constraining the radial DOF of the cup reasonably.Finally, the self-excited vibration laws of cup type pig for DN200 pipeline under different working conditions were analyzed using Matlab simulation software.It is shown that the amplitude of cup type pig increases with the increase of the interference, while increases firstly and then decreases with the increase of its running speed.In conclusion, the model and influential laws on the self-excited vibration of the pig for natural gas pipelines provide the basis for selecting the interference and running speed of cup type pig, so as to effectively improve the pigging safety and effectiveness of natural gas pipelines.