Inner Pressure/Bending Creep Test on Circumferentially Welded Large Diameter Pipe of Grade 122 Steel: Failure Life Prediction

Estimation of failure lives for welded joints in piping made of creep strength enhanced ferritic steel is of great importance for ensuring safe and sound operation of ultra-supercritical fossil power plants using this type of material. As a part of the various efforts for developing the procedure meeting this need, a large scale pipe test was performed on grade 122 pipe with circumferential welds, in order to grasp its fracture behavior as well as its predictability. Finite element analysis as well as damage calculation were performed on this test. By using creep strain equations, as well as failure criterion newly developed for this material and welded joint, both creep deformation and failure life were successfully predicted with reasonable accuracy.