Experimental Comparison of Tensile Armor Wires Using Strain Gages and Fiber Bragg Grating Techniques

Abstract

Flexible pipes are being installed and operated in more marginal and challenging offshore conditions related to deep-water environments. Especially important is the accurate assessment of the remaining life of a flexible riser so operators can avoid costly premature change outs. So, emerging inspection and monitoring technologies are being several developed to achieve a comprehensive flexible pipes integrity approach. For unbonded flexible pipes, the primary challenges include fatigue life, collapse, axial compression loading of the tensile armor wires and end fitting development. This paper is related to end fitting development area, due to necessary folding/unfolding process on the tensile armor wires during pipe assembling. This mechanical forming generates high levels of plastic strain on the wires, which may therefore reduce the fatigue life of the flexible pipe in the field. This paper presents an analysis of the high strain level involved in the folding and unfolding process along tensile armour wire, using the strain gages and fiber Bragg grating techniques. Besides that, this paper describes a comparison analysis, which correlates the performance of both methods to assess high strain levels.