Fatigue Safety Factors for the Tensile and Pressure Armours of Flexible Risers Available to Purchase

In the present paper, fatigue safety factors for metallic layers of flexible risers are assessed. A procedure for reliability analysis of wave-induced fatigue is first described. The procedure is based on performing a number of parametric studies with respect to variables that influence the fatigue lifetime. The results of these parametric studies are subsequently combined with models describing the statistical scatter of the same parameters. By application of this procedure, the safety factors which are required in order to reach specific target reliability levels can be computed. Example of calculation of such safety factors for the tensile and pressure armours of some specific flexible riser configurations are given. Different SN-curves which correspond to different corrosive environments are considered. The percentwise contribution from each parameter to the total statistical variation of the limit state function is also quantified.