Ductile-fracture arrest methods for gas-transmission pipelines using Charpy impact energy or DWTT energy

摘要

The Standardized Charpyv-notched (CVN) impact energy has been used by the pipeline industry since the 1960s to characterize fracture toughness of pipeline steels, and is central to the fracture-control technology developed for gas transmission pipelines.The drop-weight tear test (DWTT) has been standardized to assess fracture mode in such applications, with DWTT energy suggested as a means to quantify toughness, although not standardized for such a use.Battelle developed its two-curve model (BTCM) in the early 1970s to determine the required toughness to arrest ductile fracture in gas transmission pipelines in terms of CVN impact energy.The BTCM has been found viable for pipeline grades up to X-65, but issues have emerged in applications to higher grades.Thus different correction methods were proposed over the years to improve the BTCM predictions.This paper reviews the use of CVN and DWTT energy in conjunction with the BTCM to predict arrest toughness to control running fractures in gas transmission pipelines, and evaluates correction methods adopted to extend its use to X-80 and above.The correction methods include the Leis correction factor, the CSM factor, the Wilkowski DWTT method, and others.These methods are evaluated through analysis and comparison of predictions with full-scale experimental data. Suggestions to further improve the BTCM also are discussed.