During the time in service, structures and equipment components can fail and cause accidents. This usually leads to damage and may also cause loss of human lives and environmental damages. Often, harmful events are originated from materials and manufacturing faults, unforeseen overloads or other problems arising from the operation time or component maintenance deficiencies. In this study, based on the analysis of surface crack propagation under loading, was assessed the integrity of a top connecting flange of a flexible line operation under cryogenic conditions. When in service, the failure of this connector may cause production disruptions, damages to the equipment and the environment, as well as human fatalities on offshore oil platforms. In Brazil, flexibles lines (ducts) used to inject CO2 gas in oil reservoirs work subjected to high internal pressures (of the order of 10,000 psi), which increases the risk of a component failure. Moreover, the damaged flange may cause leakage of gaseous fluid resulting in very low local temperatures and resulting in brittle fracture enhancing of the component. The scenario proposed in this study is related to a possible seal BX ring failure which is located between the flexible line connection and the oil platform. The methodology was divided into two stages: the first corresponds to the linear elastic global analysis of the connector in the absence of cracks and based on the finite element method (FEM). In the second stage of analysis, it introduced a crack on the connector in the region with the highest stress levels and where it is possible to test for penetrant. Thus, the study focused on the flange connection connector, adopting as a steel with 9 per cent nickel in its chemical composition, ferrous alloy wide application in LNG storage tanks. He sought to evaluate the fracture resistance of the material through the combination of severe loading conditions, low temperatures and 9 cracks in flanges of flexible ducts as severe criteria standard API 6A standard. Thus, it is expected to contribute to the offshore oil industry has one more material option to be adopted in the manufacture of top connectors of the flexible lines working in cryogenic condition.