Branch pipe T-joints are used to connect and bifurcate hydraulic channels in big hydraulic power plants size. These components are submitted to enormous strengths that must be counteracted by integrated structures to the T-joint, for this case specified arrangement type "Nun neck". The main objective in this work is about validate structurally by numerical analysis the branch pipe T-joint design with reinforcement type “Nun Neck” to the operational established conditions in hydraulic channel design. The structural T-joint design was made following AISI Buried steel Penstocks and ASME section VIII Div. 1 standards. The simulation process was made by Multiphysics Simulation Software, Ansys Workbench V 17. The branch pipe T-joint CAD model is set as 1700 mm in diameter to flow and 1200mm to derivation. The computational simulation process was executed using the mechanical structure module in ANSYS Workbench V17.0 commercial version. The boundary conditions settings were established based on internal operational pressure given as 353.14 mWC and fixed restrictions in the areas of contact with the pipe. Equivalent Von Mises stress contours were determined looking to validate the stress state in branch T-joint, findings demonstrate that the proposed design has structural failures that must had been reinforced by civil works.