Vandiver, J.K., Swithenbank, S., Jaiswal, V., and Marcollo, H., Paper Number OTC-18276, Proceedsing of the Offshore Technology Conference (OTC), 1-4 May, Houston, Texas, USA, 2006.

Abstract

Triple helical strakes can play an important role in the suppression of VIV on offshore platforms. This paper will present results of two field experiments, one conducted at Lake Seneca in upstate New York and the second in the Gulf Stream near Miami, Florida. Three different distributions of triple helical strakes were tested. These experiments were designed to explore the effects of VIV on both bare pipes and pipes with strakes at mode numbers greater than the tenth mode in uniform and sheared currents. At Lake Seneca, bare pipe and full strake coverage pipes were tested in uniform currents. In the Gulf Stream two different configurations of strakes were tested and compared to the VIV response of a bare cylinder. The two configurations are referred to as the 40% coverage case and the 70% staggered coverage configuration. The results of these tests showed a reduction in the amplitude of the vibration and also the frequency content of the vibrations. In particular, a large third harmoniccomponent, which contributes significantly to the fatigue damage rate, was suppressed by the configurations with strakes. Together these reductions will greatly increase the fatigue life of the pipe.

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