Development of an analytical model for predicting the wet collapse pressure of curved flexible risers. (15th July 2021)

• Record Type: Journal Article
• Authors: Li, Xiao; Jiang, Xiaoli; Hopman, Hans
• Is Part Of: Ocean engineering. Volume 232(2021)
• Publication Date: 2021-07-15
• Subjects: Flexible pipes -- Curvature effect -- Collapse behaviors -- Wet collapse -- Analytical solution; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2021.109132
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: Flexible risers are designed with strong anti-collapse capacities which enable them to operate in deep-water reservoirs. However, this anti-collapse capacity is susceptible to the pipe curvature in the flooded annulus condition. For the curved riser sections within the touch-down zone, significant reduction of collapse capacity can occur once their external sheaths are worn out by the seabed, resulting in the so-called "wet collapse". Mostly, wet collapse studies of curved flexible risers are performed through costly numerical simulations since there are no alternative analytical approaches. In view of it, this work presents an analytical model for predicting the wet collapse pressure of curved flexible risers. The analytical model is developed based on a spring-supported arch model that from our previous work, which is able to take the curvature-induced factors into account. With the stability theories of arched structures, the wet collapse pressure of curved flexible risers can be solved. To verify this analytical model, 3D full FE models are employed. The critical collapse pressures predicted by these two kinds of approach are in good agreement, indicating this proposed analytical model can be an useful tool to facilitate the collapse analysis in pipe design stage. Highlights: An analytical model is proposed to account for the curvature effect in wet collapse calculations of flexible risers. The analytical model can predict the wet collapse pressure of flexible pipes in two different collapse modes. This model largely reduced the computational time in comparison with numerical simulation.