Pressure vessels are widely used in different industries, such as gas and petroleum. They may get out of service due to many reasons. However, small cracks on their surface may lead to their operation to be stopped, and their need to being repaired. Therefore, the study of the cracks so as to determine if they could continue their operation despite of their flaw or otherwise is of a great consequence. In this study we investigated the Stress Intensity Factor (SIF) and J-integral of a semi elliptical crack on a thin wall spherical pressure vessel under different internal pressures as well as different crack lengths. The simulation was done using ABAQUS Software Sub-model method. We do numerical and analytical analysis, and compared the results. The good compatibility between the numerical and analytical results for the stress intensity factor and J-integral was obtained
