Research of Socket Welds Vibration Fatigue Resistance and Application of Wavelet Transform Method in Damage Detection

Socket welds are widely used in nuclear power plants. According to industry experiences, vibration fatigue of socket welds is becoming one of the major ageing issues. It is very important for the operating engineers to monitor the vibration condition and detect the damage before leak occurs. This paper studies the damage identification technology applying wavelet transform method. Small bore pipes with socket welds are installed on the vibrating table and vibrate at the frequencies that near its first natural frequency. The acceleration response signal is acquired and decomposed by wavelet method. The energy of decomposition signal shows a suddenly variation when crack occurs. From this study, a parameter that is sensitive to vibration fatigue is defined and has the potential application value in the nuclear power plants to identify the vibration fatigue damage.