Abstract: A crude oil pipeline of Northwest Oilfield Company has been in continuous operation for nearly 15 years, during which pipeline pigging has not been carried out. In order to determine the optimal pigging cycle of the pipeline, the internal detection technology was adopted to obtain the deformation and corrosion data of the pipeline after the first pigging. And the optimal pigging cycle was finally determined from the perspectives of critical corrosion depth, ultimate bearing capacity and operation economy. The results show that the remaining life of the pipeline is 7.12 years and 5.02 years respectively by calculations from the corrosion progress formula and finite element analysis method. In addition, from the perspective of pipeline operation economy, pigging operation after 5 years of pipeline operation can reduce the cost by about 250000 yuan. Therefore, the pigging cycle of the crude oil pipeline is finally determined to be 5 years. The determination of pigging cycle can provide a scientific basis for the later maintenance of the long-distance crude oil pipeline.

Key words: long-distance pipeline, finite element analysis, critical corrosion depth, optimization of pipeline pigging cycle