Mitigating Flow Induced Vibration of Process Pipework Using Tuned Mass Dampers

Abstract Vibration, especially caused by internal flow is one of the major root causes for fatigue failures in process pipework. Over recent years significant improvements were made to provide guidance so that most problems can be avoided during the design phase [1]. For existing plants and pipework, however, it is particularly challenging and often cost prohibitive to eliminate the root cause of flow induced vibration (FIV) as this would require major changes in process conditions, process design or modifications to the physical pipework layout in terms of routing or sizing. Therefore, in most cases the only remaining option is to mitigate the vibration by modifying the support layout which includes installation of additional supports or the installation of vibration suppression devices. The most common and well-known vibration suppression devices are viscous dampers which work very reliably over a wide range of operating scenarios but come with the disadvantage of requiring sufficiently stiff steelwork to work efficiently. Another, lesser known, option, which does not require any external structure or attachment points, are Tuned Mass Dampers (TMDs). In the oil and gas industry TMDs are currently mainly used for problems associated with rotating equipment (mechanically driven, narrow band excitation energy). This paper presents when and how TMDs can be used for low frequency FIV problems (beam flexural modes) on process pipework by detailing all stages of the TMD specification. This includes the application of TMDs for steady state flow (low degree of magnitude / frequency variation), operating scenarios with varying fluid composition (higher degree of frequency variation) and flow regimes which have a significant transient component that often occur during multiphase flow with slugging regime. Based on load characteristics that are determined by the introduced analysis methods, optimization strategies for the TMD parameters will be presented and how these TMD parameters influence the efficiency in terms of achievable reduction in overall vibration levels.