Corrosion Repair of Pipelines Using Modern Composite Materials Systems: A Numerical Performance Evaluation

Pipe corrosion is a frequent phenomenon, and if repairs are delayed it could lead to environmental damage. Drilling activities can expand only when sufficient surface transportation capacity for the produced fluids exists and thus good maintenance of the transportation system is important. Furthermore, the technology presented herein can be easily upgraded as a repair solution for surface casing section below the casing head, which have been repeatedly reported as being highly corroded for older wells. This paper presents the results of the research work carried out by the authors in order to evaluate the design methods of the modern composite material systems used to repair steel pipes carrying hydrocarbons upon which local metal loss defects (generated by corrosion and/or erosion processes) have been detected. The pipe repair technologies consisting of the application of composite material wraps (made of a polymeric matrix and reinforcing fabric) are perceived as being advantageous alternative solutions for substituting the conventional technologies, which require welding operations to be performed in the corroded pipe areas. The performance and the design methods of the composite repair systems have been investigated by evaluating the reinforcement effects (the restoration level of the damaged pipe mechanical strength) generated by the applied composite wraps as a function of their geometry and mechanical properties. To that purpose, numerical models based on finite elements (previously developed by the authors and certified by comparing them with the results of several experimental programs performed within our university) have been used. The calculation methods proposed in literature (among which a method previously proposed by the authors) to define the composite wrap dimensions (thickness and length) for a given pipe have been compared to the numerical results in order to select the most adequate solution for the design of the composite repair system. The influence in the design process of the defect orientation and of its width has also been investigated.