Riser analysis

The customer

• Size: Medium-large enterprise
• Sector: Oil and gas
• Country: United Kingdom

The project

• Size: 65-80 man-hours
• Duration: 2-3 weeks

The problem

• Fatigue issues expected on the riser joints
• Early failure of the riser due to fatigue
• Fatigue useful life unknown

Proposed solution

• Fluid dynamic analysis to determine vortex shedding dynamics
• Signal processing to obtain main vortex shedding frequencies
• Determine structure's natural frequencies using a modal analysis

The simulations

• LES model to determine vortex shedding for various current velocities (CFD analysis)
• Fourier transformation for frequency signal processing
• Modal analysis to determine riser structure's natural frequencies (FEA analysis)

Project overall results

• Structure was optimised to avoid VIV frequency range.
• Savings over £38,000 for the customer in prototyping and testing (estimate).
• Savings of more than 8 weeks in development time (estimate).