TITLE:
Steel Catenary Riser Fatigue Life Prediction Using Linearized Hydrodynamic Models
AUTHORS:
C. Ebunuoha, C. V. Ossia
KEYWORDS:
Fatigue Life, Linearized Hydrodynamic Models, Steal Catenary Riser
JOURNAL NAME:
World Journal of Engineering and Technology,
Vol.5 No.4,
September
14,
2017
ABSTRACT: Steel catenary risers, (SCR) usually installed between seabed wellhead and floating platform are subjected to vortex shedding. These impose direct forces, hence cyclic stresses, and fatigue damage on the SCR. Riser failure has both economic and environmental consequences; hence the design life is usually greater than the field life, which is significantly reduced by vortex induced vibration (VIV). In this study, SCR and metOcean data from a field in Offshore Nigeria were substituted into linearized hydrodynamic models for simulations. The results showed that the hang off and touchdown regions were most susceptible to fatigue failure. Further analysis using Miner-Palm green models revealed that the fatigue life reduced from a design value of 20-years to 17.04-years, shortened by 2.96-years due to VIV. Furthermore, a maximum wave load of 5.154 kN was observed. The wave loads results corroborated with those obtained from finite element Orca Flex software, yielding a correlation coefficient of 0.975.