Interaction between an Aramid-Reinforced Flexible Composite Liner and a Carbon Steel Pipeline Containing Corrosion Defects

Internal corrosion in carbon steel pipelines is a serious challenge in the oil and gas industry. Conventional rehabilitation techniques used to stop corrosion losses and prolong the life of pipelines use an internal lining system to isolate the corrosive medium from the inner surface of the host pipe. A recent lining technology based on an aramid-reinforced flexible polymer composite liner has been successfully installed in several pipelines. It has been theorized that the added inherent strength of the liner due to the aramid reinforcement can give rise to an increased burst pressure level of the corroded pipeline. Hence, the objective of the study is to investigate, with aid of a nonlinear finite-element (FE) model, the potential structural enhancement, e.g., increase in burst pressure level of the combined liner-carbon steel pipeline system. The mechanical response of the three layers of the liner were determined experimentally and implemented in the FE model. Two different carbon steel pipelines with various internal corrosion defects were considered, and the burst pressure levels before and after installation of the liner were determined with the FE model. The results show that it is possible to achieve an increase in the burst pressure level when this liner is installed. It is concluded that this new liner can serve as a corrosive protective barrier, and in some cases provide structural enhancement to the combined pipe-liner system.