Through-Wall Extent 

TWE Through-Wall Extent – is the size of a defect as measured perpendicular to the surfaces of the component wall containing the defect. The TWE is measured perpendicular to the nearest surface of the component. The defect height is the distance measured along the face of the defect. If the defect is tilted to the through-wall direction, as in the case of defects associated with the fusion face of a weld, then the defect TWE is different to the defect height. 

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