Analytical calculation method for strain of pipeline with smooth dent based on 3D scanning

Abstract

Due to its advantages of high accuracy and strong applicability, the evaluation criteria based on dent strain is widely used to evaluate the applicability of buried long-distance pipelines with dents. In order to obtain the more accurate strain value of dent, an analytical calculation method was proposed for strain of pipelines with smooth dents based on 3D scanning profile. Specifically, the scanned point cloud data were pre-processed with the reverse engineering software, the smooth dent surface was reconstructed with the cubic B-spline interpolation function, and the point cloud data were divided into the regular grid node coordinates through data gridding. Besides, the displacement and strain of each node after dent deformation were derived based on the thin shell theory and geometrical deformation analysis,with the calculation results compared with that obtained by the finite element method and formula from ASME B31.8.According to the results, the average relative errors of maximum equivalent strain results of inner wall calculated by the proposed analytical calculation method, and formula from ASME B31.8 compared with FEA method are 17.59% and 11.56%, while that of the outer wall are 7.73% and 13.16%, respectively. Hence, the analytical calculation method is more accurate for strain calculation of the outer wall of dent than formula from ASME B31.8. In general, the research results could provide theoretical basis for the field applicability evaluation of pipelines with dents.

Keywords

• long-distance pipeline
• 3d scanning
• smooth dent
• dent strain
• analytical calculation