Reproducing Failure Mode and Life Prediction of Expansion Joint Using Field Data

In this study, among plant equipment, valve and piping fitting which is vulnerable to waterhammer was selected for diagnosis. Impulsive vibration by waterhammer was measured and applied to HIL simulator as operation data using HILS method for reproducing failure mode and life prediction of them. For effective measuring vibration, accelerometer was adapted for in the poor surroundings. Measurement results shows max. peak-to-peak vibration displacement was 21.40 mm caused by waterhammer on the valve etc., which could affect structure stability of plant equipment. After that, using the acquired data, the vibration durability of the expansion joint was tested. Meanwhile, in the case of vibration durability, internal pressure in the expansion joint was proposed as main stress factor of durability life, life prediction model was induced by curve fitting along with the datum at each pressure and verified. Thus, a further study will develop mixed life prediction model which will contain another stress factor such as temperature.