Assessment of flexible pipes with damaged tensile armor wires using finite element models and symbolic regression

Resumo

Flexible pipes are key components in several offshore oil and gas applications as production, gas lift, or
gas and water injection lines. However, these structures may be damaged during their service lives, which may
reduce their structural capacity and lead to costs associated with replacement, production loss, and oil spill. Among
the possible damages in flexible pipes, the rupture of their tensile armors is critical, as these armors sustain the
axial loads imposed on these pipes. Therefore, this paper deals with the structural analysis of flexible pipes with
broken tensile armors subjected to tension loads. A previously proposed finite element model is employed to model
the damaged pipes. Forty-seven flexible pipes are analyzed and the Stress Concentration Factors (SCF’s) of the
tensile armor wires are collected to form a database, which is then employed by a symbolic regression package to
fit analytical expressions for the obtained SCF’s. The goal of this work is therefore to find a closed formed
analytical expression for the SCF’s, which is accurate and thus able to replace a time-consuming assessment with
a finite element model.