Structural integrity is the ability of structure or a component resisting failure due to fracture and/or deformation. A piping system is a key in industrial facilities such as energy plants. In particular, seismic events can place severe stresses on piping systems. Supplemental loads and dynamic motion may induce a strong cyclic bending moment in pipes. Our group aims to clarify failure mechanism of aged piping systems under seismic loadings. This project is collaborative research between National Research Institute for Earth Science and Disaster Prevention (NIED), IHI Corporation, and YNU. Figure shows that failure occurred at wall-thinned tee in the piping system subjected to seismic loads.