Pipe-soil vibration characteristics of natural gas pipelines during the pigging process

Abstract

During the pigging process in long-distance natural gas transportation pipelines, the pig is easy to block and cannot be located accurately, resulting in serious economic losses. The analysis of pipe and soil vibration rule can be used as the basis for pig positioning. How to locate accurately the pig has become an urgent problem. In this study the coupled pipe-soil vibration model under the pigging action is proposed, and a three-dimensional symmetric pipe-soil vibration finite element model is established through ABAQUS. The influence of the pig running velocity and the friction coefficient of the inner surface on the vibration of the pipeline, as well as the influence of the propagation direction and the soil elastic modulus on the vibration propagation of the soil are studied. The research results show that the displacement amplitude of pipeline vibration increases with the increase of the running velocity of the pig, and at 0.8 m/s, the displacement reaches a peak of 27 μm. At the same time, the amplitude of pipe displacement increases as the friction coefficient between the pig and the pipeline increases. In the soil different directions, it is concluded that at 200 mm, the maximum displacement amplitude in the 45° direction can reach 15 μm. For the soil elastic modulus, when the propagation distance is 200 mm in soil with an elastic modulus of 10 MPa, the vibration velocity is significantly higher than that in other soils, and the maximum can reach 70 μm/s. Under the same conditions, the elastic modulus in the soil with an elastic modulus of 50 MPa, the maximum vibration velocity is 27 μm/s, indicating that the elastic modulus of the soil has a greater influence on the vibration velocity.