FFS Approach to Assessment of Vibrations Caused by Compressor/Pump Pulsations

Abstract Vibrations in pipeline systems often result from the periodic flow from pumps and compressors, known as pulsations. Due to similarities in the prime movers, pulsations are problematic in both liquid and gas systems. While typically not an issue in long, constant diameter runs of pipeline, pulsation induced vibrations can occur in main transportation lines as well as in supporting systems throughout pumping/compression and treatment facilities. Standards like API 618 and API 674 are used to provide guidance for predictive analysis to reduce the likelihood of pulsation induced vibrations from occurring. Predictive vibration modeling is very useful for planning purposes, but occasionally surprises occur. The analysis can be sensitive to factors that are not fully known in the design stage. Once in service, facilities may change, equipment may be added, flow rates may be increased, or fluid compositions and temperatures may vary. As a result, pulsation driven vibrations may occur despite predictive analysis. For operating systems where vibration and pulsation amplitudes can be measured, it is more appropriate to use a FFS (Fitness for Service) approach to determine if mitigations are required and the success of any applied mitigations. While this approach is more involved, it may remove excess conservatism, leading to reduced overall costs.