NDLI: Flexible Riser Fatigue Procedure Using a Long Term Distribution of FPSO’s Heading Direction

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Lemos, Carlos Alberto Duarte De Vaz, Murilo Augusto
Copyright Year	2002
Abstract	The intensive use of FPSOs in Campos Basin, offshore Brazil, has demanded more attention on the fatigue design of flexible risers. Field experience and a new set of environmental data collected in the last years have shown a large number of swell waves reaching the floating units in quartering and beam seas, which has amplified the motions at the risers’ top connections. Hence, it is necessary to evaluate the occurrence probability of wave heading direction relative to the vessel, especially for beam seas, but also noting the probability increase of quartering seas considering the existence of bi-modal and bi-directional wave spectra. The simultaneous environmental conditions — wind, current and bi-directional waves (sea and swell) — registered in Campos Basin, were condensed in a few hundreds environmental conditions to enable its utilization on a simulation program, where the FPSO, mooring lines and risers were modeled to obtain the mean heading and offsets. This new set of FPSO headings were then used to define a new proposal of load conditions to evaluate the fatigue life of flexible risers. This new procedure was then applied to a case study for the FPSO P-33 employing the tools available at PETROBRAS research center. The results have confirmed the importance of beam and quarter seas, which respectively cause heavy roll and vertical motions at the turret and then, affecting the fatigue of the risers.
Sponsorship	Ocean, Offshore, and Arctic Engineering Division
Starting Page	101
Ending Page	106
Page Count	6
File Format	PDF
ISBN	0791836142
DOI	10.1115/OMAE2002-28145
e-ISBN	0791835995
Volume Number	21st International Conference on Offshore Mechanics and Arctic Engineering, Volume 4
Conference Proceedings	ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering
Language	English
Publisher Date	2002-06-23
Publisher Place	Oslo, Norway
Access Restriction	Subscribed
Subject Keyword	Fatigue life Wind Seas Fatigue design Mooring Vessels Fpso Probability Fatigue Flexible risers Waves Stress Pipeline risers Simulation Spectra (spectroscopy) Ocean engineering Risers (casting)
Content Type	Text
Resource Type	Article

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