Stress and vibration analysis of long-distance pipeline pigging system

When pigging operation is performed in long-distance pipelines, slug flow occurs frequently, leading to significant changes in gas content and pressure of piping systems. And as a result, piping systems suffer mechanical vibration due to the slug flow. In order to solve this problem, a stress analysis model for piping systems was established by using the software CAESAR Ⅱ according to the standard ASME B31.8-2014 Gas Transmission and Distribution Piping System. Finally, the shock and vibration effects of slug flow on piping systems were investigated by means of the time-history analysis method. The stress analysis results show that the primary stress of pipelines can be satisfied in sustained load cases and the secondary stress of pipelines can be satisfied in dynamic load cases. Based on stress analysis, the force on nozzles and supports of piping systems in operation load cases is obtained. The vibration analysis on pigging systems indicates that vibration displacement of piping systems is larger in regions with slug flow and the force on supports is stronger near regions with slug flow. Furthermore, under the joint action of sustained load and dynamic load, the maximum stress is up to 54.338 MPa, which meets the requirements on stress check.