Numerical simulation of piping vibrations using an updated FE model

Traditional design and condition monitoring of piping is mainly based on postulated events and on the application of allowable vibration levels. This approach gives only indirect information on the loading at the critical locations and generally leads to over conservative assessments. It is essential that developing piping failures can be anticipated and/or monitored and that any repair work is carefully planned ahead and carried out during regular outages. In an ongoing project a practical method is being developed to monitor the condition and remaining lifetime of process piping. This method combines both measurements - using a minimum number of fixed continuous measurements - and an adequate computational model. Relatively simple piping in a NPP was chosen as the first pilot case. Measured modal shapes of the structure were excited using an impact hammer and a shaker. Results from experimental modal analysis were used in finite element (FE) model validation and updating process carried out using the FEMtools [1] code. This paper outlines the project and describes the main experiences and results of the model updating work.