Low-cycle fatigue behaviors of the elbow in a nuclear power plant piping system using the moment and deformation angle

• Published in: Engineering failure analysis 2019-02, Vol.96, p.348-361
• Main Authors: Kim, Sung-Wan, Choi, Hyoung-Suk, Jeon, Bub-Gyu, Hahm, Dae-Gi
• Format: Article
• Language: English
• Subjects: 3-in steel pipe elbow; Leakage line; Low-cycle fatigue curve; Moment-deformation angle; Nuclear power plant piping system
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2018.10.021

Maintaining the structural integrity of the major devices of a nuclear power plant is perceived as a particularly important issue in relation to the stability of the structure, and the structural integrity of the piping system is especially important for the safety of the nuclear power plant. In this study, the limit state of a steel pipe elbow, which is a fragile part of the nuclear power plant piping system, was defined as leakage, and an in-plane cyclic loading test was conducted. As it is difficult to measure the moment and deformation angle of the steel pipe elbow using conventional sensors, an image measurement system was used. A deformation angle measurement algorithm that uses an image measurement system applied an improved deformation angle measurement algorithm that uses image filter processing to facilitate noise reduction in images as well as the boundary line of the piping system. This study proposed a leakage line and low-cycle fatigue curves using the relationship between the moment and the deformation angle of a 3-in steel pipe elbow. •A leakage line was proposed using the relationship between the moment and the deformation angle of a steel pipe elbow.•Low-cycle fatigue curves were proposed for the moment and deformation angle of the steel pipe elbow.•The boundary line of the steel pipe elbow was detected using an image measurement system.