Failure information from full-thickness burst experiments on long distance gas transportation pipelines has shown that unstable fractures propagating in the pipeline axial direction are dominated by ductile slant shearing [
]. Different test samples, e.g. Charpy impact [
], drop weight tear test (DWTT) [
] and double cantilever beam (DCB) [
] have been proposed to study the ductile shear crack growth in pipeline steels in a laboratory scale experiment. Because of the design geometry of these specimens, slant crack growth is often preceded by flat fracture in the specimen un-cracked ligament.