Evaluation of Composite Hull for Subsea Separator

Resumo

The subsea separator is one of the most important equipment to subsea processing, since it is responsible
for separating the fluids extracted from the reservoir. The separation module may be composed by injection bombs
and several other equipment, besides the separator tank, which makes it a huge structure. Since it is made of steel,
the separator hull is extremely heavy and expensive, requiring very specific and expensive crane vessels for
installation. Composite materials made of polymeric resins and fibers usually have very low density compared to
steel, good mechanical properties, which make them a feasible alternative to weight reduction without losing
structural safety. Therefore, it is important to evaluate its mechanical properties under the operational conditions
to validate the proposed application. This work evaluated salt water absorption of composite plates under
conditions of 3000 psi of external pressure and temperature of 4oC. Tensile and shear tests were performed to
assess the influence of water absorption on the resistance and elastic and shear moduli of the material. A numerical
model was also developed to evaluate the behavior of the structure under different levels of external pressure and
to compare a metallic with a composite hull. It was possible to conclude that the absorption did not cause
significant changes on the elastic and shear moduli nor on the tensile strength of the material. In addition, the
numerical results showed that, for the same external pressure, the composite hull has a thicker wall and a lower
mass when compared with a metallic one.