Vibration Assessment Methodology for Subsea Pipework

Vibration is an important cause of fatigue damage in subsea piping systems (jumpers, rigid spools, tree pipework etc.). Presently, guidelines are available for a qualitative and quantitative vibration assessment for process pipework, but these are more applicable to topside and refinery piping. Currently, there are limited guidelines specifically developed for vibration assessment for subsea piping. For subsea pipework, additional guidelines may be necessary to check for possible interaction between current induced VIV, wave induced VIV (for shallow waters) and slugging, and other mechanisms that result in flow induced vibration. This paper provides augmented guidelines for subsea piping, which takes into account the interaction between piping and its subsea environment. At the same time, suggestions are provided to trim the guidelines of mechanisms that does not occur subsea. The Likelihood of Failure (LOF) assessment based on the proposed guidelines provides an indication whether further detailed vibration analysis (such as CFD and/or FEA) is necessary. Based on the LOF from this assessment, suitable detailed analysis can be performed to determine the fatigue life. This enhanced methodology enables the user to perform vibration assessment and analysis in the least computational time by identifying 1) the most critical flow conditions over the production life of the field and 2) the most critical vibration mechanisms that should be analyzed. This results in a reduction in the number of conditions or load cases which require detailed analysis, without decreasing the accuracy of the assessment and analysis.Copyright © 2011 by ASME