Planning for shake down
Design improvements at operating power plants continue to challenge plant staff and original equipment manufacturers (OEMs). While basic design calculations consider the capacity of components and stresses resulting from their use, few consider vibration issues in great detail in the design. Vibration can lead to instrumentation failure, cracking and fatigue damage, or early degradation of the installed equipment, leading to increased OEM costs and plant outages.
This is usually justified since realworld vibrations from flow-induced sources or interaction with plant-supporting structures are notoriously hard to predict. Typically, only rotating equipment receives consideration of operating vibration issues. For most systems, there are far too many potential vibration response modes and potential sources of vibration unique to the specific installation to design around all of the problems. Therefore, it is critical to provide for initial shake-down testing of the system and to plan for the diagnosis of potential problems.
Diagnosis of vibration issues is more than simply taking accelerometer data at specific locations. Real diagnosis should attempt to determine the cause of the vibration through evaluation of structures responding to the vibration source. This can include computer modeling of building steel, piping systems, or even acoustic or computational fluid dynamics models for flow-induced vibration (FIV) issues.