Optical Sensors Monitor Vulnerable Top Sections of Flexible Risers

Fig. 2—Spyhole end-fitting.

The integrity management of flexible pipes used in subsea production plays a major role in maximizing the availability of the production systems while minimizing safety and environmental risks. One of the key areas for integrity management is the riser top section, where high tensions and curvatures result in high stresses and may lead to fatigue issues. A monitoring technique known as Monitoring Based on Optical Fiber Attached Directly on Armor Wires, or MODA, has been developed to assess the integrity of the tensile armor at the top section of flexible risers.


A flexible pipe is composed of several layers, each having a specific function (Fig. 1). The carcass is a metallic layer designed to withstand external compression forces in the radial direction. The internal pressure sheath is a polymeric layer used to contain the fluid inside the pipe. The pressure armor is a metallic layer designed to withstand the internal pressure. The tensile armors are made of metallic wires designed to resist axial forces acting on the pipe. In risers, the tensile armors are responsible for keeping the flexible pipe suspended from the floating production unit (FPU). The outer sheath wraps the other layers, protecting them from the external environment. The region inside the internal pressure sheath is called the bore, and the region between the pressure barrier and the outer sheath is known as the annulus space.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 28080, “Monitoring Flexible Risers With Optical Sensors—Operational Experience and Future Perspectives,” by B.M. Santiago, S.R. Morikawa, W. Carrara, A. Kravetz, and J.A. Martins, Petrobras, prepared for the 2017 Offshore Technology Conference Brasil, Rio de Janeiro, 24–26 October. The paper has not been peer reviewed. Copyright 2017 Offshore Technology Conference. Reproduced by permission.
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Optical Sensors Monitor Vulnerable Top Sections of Flexible Risers

01 February 2018

Volume: 70 | Issue: 2


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