The modern approach of Virtual Engineering allows one to detect with some accuracy the residual life of components especially free of cracks. The life estimation becomes cumbersome when the components contain a crack. A straightforward formulation requires a parameter that considers geometrical constraints and materials properties. The magnitude of the stress singularity developed by the tip of a crack, needs to be expressed by the Stress Intensity Factors (SIF). In order to prove the validity of the results, calibration by experimental and/or analytical technique is required. To have a better understanding of this parameter, in the first part of this paper an analytical model to compute the SIF connected to crack propagation into Mode I has been implemented. The case study displays a pipeline component with a crack defect submitted to internal pressure. Therefore, an appropriate correlation between the analytical approach and numerical simulation has been established embedded.