Study of an Alternative Material for the Manufacture of Subsea Umbilical Hydraulic Hoses Available to Purchase

Hydraulic hoses are components of subsea umbilicals that are responsible for Xmas tree gate valves actuation. These hoses are susceptible to collapse by external pressure and, since they are fabricated of rigid polymers, this failure can lead to strain concentration at specific points across the circumference, leading to rupture due to high internal pressure. The objective of this work is to study an alternative material to be employed in the manufacture of the hydraulic hose liner that can support the internal pressure (associated to the aramid layer) after an eventual collapse, and that have no chemical interaction with the hydraulic fluid used. This study is based on the comparison between the material currently used (Polyamide 11) and a fluorinated elastomer, Viton^®. To compare the mechanical behavior of both materials, uniaxial tensile tests as well as nonlinear finite elements models were performed. The results obtained by finite element analysis showed that both, Polyamide 11 and Viton^®, did not fail under external pressure. However, Polyamide 11 concentrates high plastic deformations after collapse that can lead to located hose rupture under internal pressure. For Viton^®, it was found that the material concentrates deformations during collapse but these deformations are recovered when internal pressure is applied. Considering that the external aramid layer is responsible to withstand the internal pressure in both cases, Viton^® can successfully replace Polyamide 11 for this application.