Influence of temperature on pull out tests on different steel-epoxy systems used in end fittings of flexible pipes

ABSTRACT In the offshore oil fields located in deep and ultra-deep waters they are used flexible pipes. In many cases inside these pipes, the hydrocarbons are transported at elevated temperatures. At the ends of the flexible pipes are installed end fittings, these are the connection with sea platforms and different subsea systems. In the assembly of end fittings, epoxy resin is used to embed the steel wires of the tensile armor and, in this way, form the anchorage system. Pull out tests allow to study the interaction between the materials that form the anchoring system. The aim of this work is to analyze the shear stress which tends to separate the joint composed to the epoxy resin and wire armor tensile of flexible pipe under different temperatures. Thus pull out tests are performed under two different temperatures (23 ° C and 100 ° C) in samples made with three different epoxies. Were analyzed two values of shear stress calculated in different phases of the test, one that is dependent on the polymer adhesion to steel, and the other is dependent on the friction between the materials. For each of the cases using ANOVA analysis, it was determinate that the temperature increase affects the two parameters studied decreasing its value and this is repeated for the three resins evaluated. Furthermore it was observed that the resins with inorganic and aluminum filler were less affected with respect which had not those fillers. This study show the importance of selection and application appropriate of epoxy materials used inside of the end fittings, because a failure is very dangerous to the environment and production.