Session: 08-05-01 Internal Flows & FIV

Paper Number: 127983

127983 - FIV Assessment Of Piping Systems Using Vibration Screening And Advanced Analysis Methodologies 

The applicability of the Likelihood of Failure (LOF) screening methodology, as proposed by the Energy Institute (EI) guidelines, is investigated for a water injection piping system with complex geometry. A combination of transient computational fluid dynamics (CFD) and finite element (FE) analyses in ANSYS Workbench software package is employed for the assessment of the flow-induced vibrations (FIV), considering one-way fluid-structure interaction (FSI) effects. Two models are considered, namely, Model 1 that comprises 16”-18” piping and a manifold that distributes the flow to seven 6” risers (Model 2).

Flowrates that correspond to a critical LOF=0.5 for Model 1 and Model 2 are assessed through CFD and FEA analyses. The resulting pipe deformations are post-processed to assess the acceptability of the vibrations in the Velocity RMS – Frequency domain, according to the EI Vibration Assessment methodology. FIV-induced stresses and fatigue damage are also assessed against structural limits, ensuring safe operation of the piping system. In case of predicted failure occurs for the specific flowrate, lower flowrate is considered iteratively until an acceptable solution is achieved. Then, the LOF is re-calculated for the limiting flowrate and compared against the critical value of 0.5.

For both models, the flowrate for the critical LOF value of 0.5 causes vibrations that fall into the problematic zone according to the EI Vibration Assessment methodology. Lower flowrates were analysed to find the limiting rate, with the re-calculated LOF falling lower than the critical value. Failure mitigation measures are proposed and analysed to allow the flowrate that corresponds to LOF=0.5 to be safely accommodated by the piping system. It should be noted that since the two models are connected in series, the critical flowrate of Model 1 will affect the maximum flowrate that Model 2 can accommodate.

Despite the fact that the LOF screening is widely used for assessing the flow capacity of pipelines and piping systems for safe operation conditions in an efficient manner, the LOF screening is mostly appropriate for straight segments of pipework, not for complex geometries that comprise a plethora of flow domain variations, such as elbows, tee-joints, control valves, small bore connections and reducers. Results presented in this work indicate that for complex geometries the LOF screening may not be sufficient to ensure no FIV failures and shall be performed alongside more advanced CFD/FEA analyses.

Presenting Author: Panagiotis Skarlas Worley

Presenting Author Biography: A highly motivated and results orientated Senior Subsea and Hydrodynamics Engineer with 8 years of work experience and proven track record of providing professional engineering and consulting services to the Energy Sector. The wide field of work experience includes assessments of SURF products and subsea structures for key global energy projects and subsea interconnectors, array and export cables and CPS de-risking, verification and installation for the largest offshore wind farms globally. As a researcher, I focused my work on improving the understanding of fluid-structure interaction for small-diameter fixed pipelines and subsea cables leading to cost-efficient solutions for the energy industry. As a professional engineer, I have participated in several challenging projects and used high-end industry tools and optimisation to achieve optimal results and deliver within the time frame.

Authors:

Panagiotis Skarlas Worley
Deborah Ibrahimi Worley
George E. Varelis Worley
Deng Peng Worley