Stress and Displacement in Pigging Process of Suspension Cable Spanning Natural Gas Pipeline

摘要

The main load-bearing component of a suspension cable spanning natural gas pipeline is a cable with considerable flexibility, which is prone to large deformation and stress under the action of pigging load. Once load exceeds the design allowable value, the safety of the entire spanning structure will be affected. Therefore, the risk of the pigging process must be strictly controlled to prevent failure accidents. Due to the differences in the form of a cable system, tower, stiffening beam, and pipeline space erection of different suspension cable natural gas pipelines, it is necessary to carry out modeling calculation and check according to the actual situation. Taking the Menggang River suspension cable spanning a natural gas pipeline as an example, the simulation model consistent with the actual bridge completion state was first established. Then the stress and displacement of the spanning pipeline under different types of loads were calculated and analyzed, and the ultimate pigging condition was obtained. Finally, according to the operation condition of the Chupan pipeline, the risk of spanning pipelines in daily pigging operation was analyzed, and some suggestions are given. The results indicate that the prestress deviation between the simulation models' calculation results and field test data of the suspension cable spanning a natural gas pipeline with 1.86-m arch height is less than 4%, so the model has high accuracy, which can be used for external load loading. Under the pressure test condition, the load is uniformly distributed over the pipeline, and the displacement and stress do not increase significantly compared with that without external load. Under the influence of arch height, the maximum stress and displacement of the spanning pipeline increase with the increase of pigging load mass, length, and position. Affected by the arch height, the stress at the south bank elbow reached the limit values specified in the standard at first, and the maximum displacement change occurs to half the span. Only when the stress and displacement are checked to be in compliance with the requirements of the standard can the safe pigging conditions be determined. In pigging operation, it is necessary to prevent the pigging load weight and length from exceeding the limit value at the same time.