Abstract: In this paper,the elasto-plastic FEM is used to evaluate limit loads for equal-diameter piping branch junctions with local wall-thinning under internal pressure.Numerical examples of non-defective equal-diameter piping branch junctions show that the computed results are in good agreement with available experimental data.The size effects and the influence of local wall-thinning positions on the plastic limit loads of equal-diameter piping branch junctions are investigated.Some typical failure modes of equal-diameter piping branch junctions with local wall-thinning are studied.The obtained results may provide theoretical bases and numerical references for structural design and safety assessment of equal-diameter piping branch junctions with local wall-thinning.