Abstract: During the long-term service of flexible risers， problems such as permeation in the annular layer and interlayer friction may occur. Under alternating loads， the fatigue damage of the tensile armor wire will accelerate. This paper conducts a safety assessment for steep-waveform flexible risers. By establishing a global-local-failure finite element model that takes into account interlayer friction and corrosion effects， the dynamic response and fatigue life of the flexible risers under the full coupling model are mainly studied. The results show that both interlayer friction and corrosion effects will affect the in-service life of the flexible risers. Interlayer friction mainly increases the stress amplitude of the tensile armor wire， while the corrosion effect not only reduces the cross-sectional size but also requires the selection of the corresponding S-N curve due to the presence of the corrosive environment. The corrosion effect has a greater impact on the fatigue life. Therefore， when conducting in-service riser assessment， interlayer friction and corrosion fatigue issues should be fully considered， and effective measures should be taken to manage the integrity of the flexible risers.

Key words: flexible riser, interlayer friction, corrosion effect, local strength, fatigue life