Umbilicals which connect an offshore floating platform (for drilling, or production and/or storage) and the devices on the sea bed used for the drilling or production form a very important component of the floating system. Different types of umbilical are designed for different purposes: to provide the power to the subsea devices, to control of the operation of the subsea devices, and provide materials needed for the operation of the subsea devices. Therefore, the integrity of the umbilical design/analysis is critical to the operation of the system. The fatigue damage to the umbilical is an important part of the umbilical's integrity assessment. The umbilical VIV contributes significantly to the umbilical's total fatigue. A procedure for a sound assessment of the umbilical fatigue damage due to VIV for practical design and engineering of the umbilical system is proposed in this paper. Special attention will be given to the quality check and processing of the results from the commercial software used for the analyses at each step (identifying and removing numerical noises in the results) before going to the next step, thus avoiding the contamination on the final results by the numerical noises.


Umbilicals are used in offshore drilling or production/storage platforms (fixed or floating) to connect the platforms to the subsea devices on the seabed and supply necessary control, energy (electric and hydraulic) and chemicals to the subsea devices such as oil & gas wells, subsea manifolds. BOP, and any subsea systems requiring remote control (for example, a ROV). Subsea intervention umbilicals are also used for offshore drilling and workover activities. Umbilicals are very important components of an offshore platform. The integrity of the umbilical design/analysis is critical to the operation of the system. In order to have a sound assessment of the integrity of the umbilical design, a good understanding of the internal loads within the umbilical and a good estimate of the loads during the designed operation in the specified environments are very important. The integrity assessment includes the examination of the strength of the umbilical (maximum stress level) and the fatigue life.

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