A calculation method for the strain of pipeline dents based on ILI data

In this paper, the strain of dents was calculated and analyzed to figure out the effect of dents identified by inline inspection (ILI) on structural strength of pipelines, so as to provide effective guide for the excavating verification and restoration of pipeline dents. The calculation methods and technical routes of dent strain based on ILI data were investigated and summarized, and the necessity and feasibility of filtering analysis were presented. Combined with ASME B31.8-2010 standard and actual ILI data, the strain was calculated by using 7 typical filtering methods. The effects and applicability of different filtering methods on data processing and strain calculation of pipeline dents were studied by comparing the strain calculation results. It is shown that it is technically feasible to calculate strain based on ILI data of pipeline dents. Based on low-pass filtering methods, the pipeline dent data is well filtered and the calculated dent strain is more reasonable. As for low-pass filtering methods, the appropriate selection of cutoff frequency parameters is crucial to the accurate calculation of dent strain, and the value of cutoff frequency is in close relation with the size of noise contained in ILI signals.