Parametric Analysis of Steel-Tube Umbilical Armor Pots

Abstract

Armor pots are mechanical devices employed in the offshore oil production to anchor armor wires/steel tubes of an umbilical cable. In epoxy-based armor pots, this anchoring is obtained through the interaction between the resin and the tensile armors/steel tubes and also through the capstan effect from geometric variations, such as radius and lay angle changes. In this context, friction plays a fundamental role in the anchoring capacity and is mainly affected, among other factors, by the intensity of resin thermal contraction, which generates positive pressure at the contact interfaces, and also by the friction coefficient. Therefore, this works presents an extensive parametric analysis of the resin thermal contraction and of the friction coefficient performed through the finite element method with the objective of understanding their qualitative and quantitative influence at the anchoring capacity of a steel-tube umbilical armor pot. In recent years, the authors published fully three-dimensional finite element models of armor pots. In order to accomplish the present work, several enhancements were performed in the aforementioned models. The main development is an innovative methodology for the resin mesh generation, ensuring mapped elements at the interfaces with steel tubes, resulting in a smoother contact representation. At the same time, this methodology is computationally advantageous by allowing larger element sizes at the remaining resin volume without loss of quality in the representation.