Vortex-Induced Vibration (VIV) suppression systems are made of polyurethane and feature a symmetrical segmented structure secured with metal strips. They can be pre-installed or installed directly on offshore pipelines and risers. By disrupting water flow and shedding vortices, polyurethane VIV strakes effectively reduce vibration amplitude and extend the service life of pipelines and risers. Their geometric designs include commonly used 16–17.5D pitch × 0.25D fin height or 5D pitch × 0.14D fin height, optimized using computational fluid dynamics (CFD) for optimal vibration suppression.
Why polyurethane?
High elasticity and damping properties
Polyurethane has a lower elastic modulus than steel, allowing it to deform more significantly under vortex-induced loads, absorbing energy and reducing fatigue stress, at only 1/5–1/3 that of steel.
Excellent damping performance, with a loss factor significantly higher than steel, allows rapid conversion of vibration energy into heat, reducing vibration amplitude by 30%–50%. At a flow rate of 2 m/s, the vibration amplitude of the polyurethane strakes can be controlled to within 0.2 mm.
Corrosion resistance
Polyurethane is resistant to corrosion from seawater, acids, alkalis, and organic media, and its strength degradation in long-term salt spray environments is much lower than that of stainless steel.
The smooth surface resists the growth of barnacles and algae, preventing biofouling that can cause flow field distortion and increased vibration.
Lightweight and mechanical compatibility
With a density approximately 1/6 that of steel, it can reduce overall loads by 15%–25%, lowering the strength requirements of the platform and support structure.
Adjustable mechanical properties, with a tensile strength of up to 50 MPa and a fatigue limit of 20 MPa, meet the requirements of long-term deep-sea service.
Easy processing and installation
Polyurethane is suitable for custom designs and can be injection molded, achieving high dimensional accuracy without the need for welding.
The modules are lightweight, and splicing and installation efficiency is approximately 40% higher than steel strakes.
With its advantages of high elastic damping, corrosion resistance, lightweight, and easy processing and installation, polyurethane has become an ideal material for VIV strakes, providing efficient and reliable vibration suppression protection for offshore pipelines and risers. Philson is a polyurethane manufacturer specializing in the design and manufacture of offshore cable protection systems. Please contact us for inquiries.
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