A unified theoretical solution of plastic limit load for the thin-walled pipeline with an incomplete welding defect

In this work, a unified theoretical solution of plastic limit load for thin-walled pipeline with an incomplete welding defect is proposed by the Net Section Collapse (NSC) criteria. The plastic limit torque of the thin-walled pipeline with an incomplete circumferential welding defect is calculated by the sand pile analogy method. The unified theoretical solutions of plastic limit loads for the pressure pipeline with a circumferential welding defect under combined tension, torsion and bending moment are deduced, and the influences of circumferential length and defect position on the plastic limit loads are discussed. The comparison with the finite element (FE) results show that the theoretical plastic limit loads of the pressured circumferentially defective pipeline based on the extended NSC criteria are reliable. The study can provide an important theoretical basis to establish the safety evaluations towards the pressure pipelines with incomplete welding defects.