Detailed FSI Analysis Methodology for Subsea Piping Components

Flow Induced Vibration (FIV) is one of the important phenomena that contribute to failure of subsea piping components. This paper addresses a detailed methodology to analyze the structural response caused by unsteady multiphase flow within a pipe. This fluid-structure interaction (FSI) study was conducted in a two-bend model of a rigid M-shaped jumper to estimate the stresses and pressure fluctuations and determine the level of risk of failure. Initially, a risk assessment method was carried out to determine the likelihood of failure (LOF) due to flow induced turbulence. Following the screening method, a detailed “two-way coupling” FSI study is recommended. Coupling the Finite Element Analysis (FEA) program with the Computational Fluid Dynamics (CFD) program allows to perform the following assessments: • Strength check (Allowable stress); • Fatigue analysis, and; • Engineering criticality assessment of welds. The two-way coupling analysis also compares the structural natural frequencies to the slug frequencies. Depending on the percentage difference between the two frequencies, a conclusion can be drawn in terms of level of risk and address whether assessing FIV fatigue damage should be required for future examination.