VIV is caused by the regular shedding of vortices in the wake behind riser and flowline pipes in steady current. The flow naturally "locks in" to shed these vortices in the same pattern at the same frequency along a significant length of pipe. This "lock in" is measured by the spanwise coherence and can cause the pipe to vibrate.
VIV causes accelerated fatigue damage and can give rise to problems such as pipe girth weld failure or premature pipe failure. Steel Catenary Riser (SCRs) and rigid steel flowlines unsupported over free spans are prone to this phenomenon.
To suppress the damaging vibration forces to an acceptable level Trelleborg Offshore developed a comprehensive analytical design and engineering package complete with a number of highly successful VIV suppression products.
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