A sensitivity study of the density of initial profile data on the deformation capacity of line pipes is represented in this paper, which profile data are used for finite element analysis (FEA). An X65 line pipe with outside diameter of 610mm and wall thickness of 12.2mm and an X80, 1220mm, 22.5mm line pipe are used for the sensitivity study. The surface profiles and thickness distributions are measured by using grids of 25 and 50mm squares drawn on the surfaces of 610 and 1220mm line pipes, respectively. The initial profiles of the 610mm line pipe are employed for FEA by changing the grid size as 600, 400, 300, 200, 100, 50, or 25mm squares. Those of the 1220mm line pipe are considered varying the grid size as 1200, 800, 600, 400, 200, 100, or 50mm squares. The line pipes unpressurized or pressurized to 40 or 60% SMYS are used to discuss the compression capacity, and those pressurized to 40 or 60% SMYS are employed to investigate the bending capacity.

The compression capacity is discussed with respect to the critical compressive strain. The results of FEA clarifies that the critical compressive strain of the unpressurized 610mm line pipe becomes 0.94 to 1.05 times as large as that calculated without initial profile data. In case the line pipe is pressurized, the critical compressive strain varies from 0.94 to 1.02 times as large as that obtained without initial profile data. It is recognized from the results that the critical compressive strain is independent of the grid size of initial profile data. The results of the 1220mm line pipe represent almost the same tendency as those of the 610mm line pipe. The bending capacity is discussed with respect to the global bending strain. The results explain that the global bending strain values of the 610mm pressurized line pipe become 0.34 to 0.58 times as large as that calculated without initial profile data. In addition, in case the 1220mm line pipe is pressurized, the global bending strain values become 0.46 to 0.75 times as large as that obtained without initial profile data. Consequently, it is recognized that the effects of the grid size of initial profile data on bending capacity are significant compared to those on compression capacity.


Effects of Profile Data Grid on Deformation Capacity of Line Pipes

Division / Sponsors: 
Pipeline Systems Division

Paper Proceedings: https://asmedigitalcollection.asme.org/IPC/IPC2020/volume/84447

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