A modified two-curve model for running fracture arrest design of high-strength transmission pipelines

摘要

Running-fracture control is a critical technology developed for gas-transmission pipelines to avoid catastrophic failure.The Battelle two-curve (BTC) model developed in the early 1970s has been widely used in the pipeline industry to determine arrest toughness in terms of the Charpy energy. Because of its calibration data limitation, the BTC model does not work for higher grades than X-65. Many other methods were thus investigated in order to predict arrest toughness required for high-strength pipeline steels. However, a brief review of running-ductile-fracture control made in this paper shows that the Charpy-energy-based two-curve model remains viable and deserves further study. The BTC model is known to be only able to predict arrest toughness, but not arrest distance.To fill the technical gaps, this paper develops a modified two-curve (MTC) model and a fracture-arrest-distance model in reference to the Charpy energy.The MTC model coupling with the arrest-distance algorithm can predict both arrest toughness and arrest distance in one simulation for a single pipe or a set of multiple pipes with given toughness.Two full-scale burst test data for X-70 and X-80 pipes are used to validate the proposed models, and the results show good agreements between the predictions and full-scale test data of both arrest toughness and arrest distance.The MTC model is then applied to optimize a design of pipe layout for a mock-up full-scale burst test on a high-strength pipeline steel. The MTC simulation results show that different pipe arrangements result in different arrest toughnesses and arrest distances for the same grade pipes.