A method of predicting the leak/rupture criteria for API 5L X80 and X100 linepipes was evaluated, based on the results of hydrostatic full-scale tests for X60, X65, X80 and X100 linepipes with an axially through-wall (TW) notch. The TW notch test results clarified the leak/rupture criteria, that is, the relationship between the initial notch lengths and the maximum hoop stresses during the TW notch tests. The obtained leak/rupture criteria were then compared to the prediction of the Charpy V-notch (CVN) absorbed energy-based equation, which has been proposed by Kiefner et al. The comparison revealed that the CVN-based equation was not applicable to the pipes having a CVN energy (Cv) greater than 130 J and flow stress greater than X65. In order to predict the leak/rupture criteria for these linepipes, the static absorbed energy for ductile cracking, (Cvs)i, was introduced as representing the fracture toughness of a pipe material. The (Cvs)i value was determined from the microscopic observation of the cut and buffed Charpy V-notch specimens after static 3-point bending tests. The CVN energy in the original CVN-based equation was replaced by an equivalent CVN energy, (Cv)eq’ which was defined as follows: (Cv)eq = 4.5 (Cvs)i. The leak/rupture criteria for the X80 and X100 linepipes with higher CVN energies were reasonably predicted by the modified equation using the (Cvs)i value.
- International Petroleum Technology Institute
Modified Equation to Predict Leak/Rupture Criteria for Axially Through-Wall Notched X80 and X100 Linepipes Having Higher Charpy Energy
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Kawaguchi, S, Hagiwara, N, Ohata, M, & Toyoda, M. "Modified Equation to Predict Leak/Rupture Criteria for Axially Through-Wall Notched X80 and X100 Linepipes Having Higher Charpy Energy." Proceedings of the 2004 International Pipeline Conference. 2004 International Pipeline Conference, Volumes 1, 2, and 3. Calgary, Alberta, Canada. October 4–8, 2004. pp. 1823-1832. ASME. https://doi.org/10.1115/IPC2004-0322
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