The purpose of this paper is to provide a research result of the inelastic stress analysis for the vessel-nozzle intersection with large opening (d/D≥0 5) under increasing internal pressure loading by test and non-linear finite element method. The determination of the limit load due to the internal pressure is performed by experimental study to compare with those from the finite element analysis results. The spread procedure of plastic area for the analytical model vessel is provided. Also this paper provides some data to serve as the proofs of the existing design method and the basis for developing a advanced design guideline of large diameter ratio shell intersections under internal pressure loading.
