The structural integrity assessment of pipes with circumferential surface flaw under the plastic collapse regime consists of net section collapse analysis. In recent years various researchers showed that this analysis, which has been developed based on classic beam theory, has certain inaccuracies. As such, assessment purely based on net-section collapse and beam theory can lead to both conservative and unconservative results.
To address those inaccuracies, in this paper the authors propose a correction factor which aims to mitigate the difference between the experimental results and ASME B&PV Code Section XI equations. This correction factor is calculated using an empirical formula developed on the basis of a large experimental database of pipe collapse bending tests containing variety of diameters, thicknesses, flaw depths and flaw lengths.
In this work, the authors took a systematic approach to identify the most influencing factors on such a correction factor and showed that by applying this correction factor to the current solution of ASME B&PV Code Section XI, the resulting solution becomes more accurate. This corrected approach also is in line with ASME B&PV Code Section XI Appendix C practice for axial flaw in pipes, where a semi-empirical correction factor has been considered as well.