Flexible pipe risers are often protected from over-bending with a bend stiffener at the lower end of an I-tube in FPSO installations. Due to the high thermal resistance of the polyurethane bend stiffener, there is a potential risk for both riser and bend stiffener to exceed their temperature limits. This paper presents classical and computational fluid dynamics thermal models and analyses to confirm that free convection heat transfer from the pipe wall to the water in the gap between the pipe and bend stiffener, and buoyancy driven flow along the gap is sufficient to maintain the temperature of the pipe layers and bend stiffener within allowable values. Details of the models and solutions for an example riser with 120 °C design temperature in a Gulf of Mexico installation is presented.

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