The production and exploitation of oil and natural gas reserves environmentally challenging regions imposes many technological challenges related to new design requirements. Engineering Critical Assessment (ECA) is an umbrella term for complex methodologies used o assess the criticality of defects in welded structures. ECA is commonly used for oil and gas industry to derive tolerable defect sizes during installation and operation of risers. Current standardization efforts make extensive use of single edge notch tension (or SENT) specimen to reduce the level of conservatism during the assessment. A great effort has been made to evaluate CTOD as a mean to assess fracture toughness, especially for offshore structures. The double clip gage method (DCGM) is an alternative CTOD test method, which produces less conservative values comparing with J-integral conversion into CTOD. In this paper, a novel CTOD definition is developed according to the philosophy of the DCGM, but requiring a single clip gauge and providing values similar to the J-integral converted CTOD. Further details need to be validated and studied to increase the applicability of the previous proposal. So, motivated by the earlier explanation, the goal of this paper is to present a new methodology to estimate the CTOD using geometrical relationship on crack opening displacement over the crack flank.