| description abstract | Singleedge notched tension (SE(T) or SENT) specimens have been increasingly proposed as a lowconstraint toughness test to measure toughness of line pipe materials, as the crack tip constraint approximates a circumferential surface flaw in a pipe under loading. The clamped SE(T) singlespecimen procedures recently developed by Shen and Tyson (2008, “Fracture Toughness Evaluation of High Strength Steel Pipe,†ASME Paper No. PVP200861100; 2008, “Development of Procedure for LowConstraint Toughness Testing Using a SingleSpecimen Technique,†CANMET Materials Technology Laboratory, Technical Report No. 200818 (TR)) and Tang et al. (2010, “Development of the SENT Test of StrainBased Design of Welded Pipelines,†8th International Pipeline Conference, IPC 2010, Calgary, AB, Canada) have both used in common the use of a clamped singlespecimen of similar geometry and relied on the unloading compliance technique for crack size estimation. In the former case, a single clip gauge is attached to the integral knife edge and the cracktip opening displacement (CTOD) is estimated by means of a JintegraltoCTOD conversion, similar to the procedure of ASTM E182011. The latter uses a pair of clip gauges mounted on an attachable raised set of knife edges to estimate CTOD at the original crack tip position by a triangulation rule. Consolidating these two sets of clip gauges in a specimen makes direct comparisons of two SE(T) methods under identical test conditions: material, specimen geometry, equipment, test temperature, and operator (Weeks et al., 2013, “Fracture Toughness Instrumentation Techniques for SingleSpecimen Clamped SE(T) Tests on X100 Linepipe Steel: Experimental Setup,†6th Pipeline Technology Conference, Ostend, Belgium). In this study, SE(T) testing employing these two SE(T) methods on a single specimen was conducted on B أ— B shallowcracked (a/W ∼ 0.35) specimens of two X70 pipeline girth welds. This paper discusses details of the two SE(T) methods and techniques on the same specimen. | |
