Recent industry experience is showing that modern high grade linepipe steels are not exhibiting the same fracture behavior as older steels of the same or lower grade. One result is that past material qualification test methods are breaking down for these new steels and may no longer provide acceptible design guidance. Drop-Weight Tear Testing (DWTT) may provide invalid results due to Abnormal Fracture Appearance (AFA), such as unacceptable fracture initiation under the notch or inverse fracture occurrence. There are also concerns about how to assure resistance to propagating ductile fractures....
Recent industry experience is showing that modern high grade linepipe steels are not exhibiting the same fracture behavior as older steels of the same or lower grade. One result is that past material qualification test methods are breaking down for these new steels and may no longer provide acceptible design guidance. Drop-Weight Tear Testing (DWTT) may provide invalid results due to Abnormal Fracture Appearance (AFA), such as unacceptable fracture initiation under the notch or inverse fracture occurrence. There are also concerns about how to assure resistance to propagating ductile fractures. This report provides the results of the PRCI project MAT-8-1 first phase and addresses criticalities of DWTT and concerns with propagating cracks in Gas transmission pipelines made from modern API X65-X80 steels with high upper shelf Charpy energy, including smaller diameter pipes (over 12 inch). On the metallurgical side, a review of steel making practices has been carried out as a function of time and with respect to developing modern high upper-shelf Charpy energy (USE) steels. On the structural integrity side, industry concerns over DWTT have been collected with respect to accurate evaluation of transition temperature and prediction of ductile fracture propagation resistance and have been accompanied by a gap analysis of what is needed to establish confidence in using modern high upper-shelf Charpy energy steels for gas pipelines. Finally a path for further investigation is proposed to address current limitations and industry concerns, supported by an Appendix that presents an alternative approach to characterize the phenomenon that has been termed running fracture, which opens to alternative approaches to quantify steel resistance to that process.