Argentina has a large, high pressure, pipeline system that transports natural gas from the production wells to the main cities. The primary trunk pipelines of this system are more than 30 years old, and coated with asphalt materials that have suffered severe degradation over time. Importantly, there are no alternative lines to transport the gas, preventing the old pipelines being taken out of service during rehabilitation. This Paper describes the experience gathered by TGS (Transportadora de Gas del Sur) in Argentina, between 1996 and 2003, in the rehabilitation of its transportation pipelines using cold applied polyethylene tapes for recoating. When a rehabilitation project is evaluated, the overall integrity of the pipeline has to be analyzed, in order to verify if, at the actual corrosion level of the pipes, an effective repair method can be used. Once the evaluation has been done, a technical and economic evaluation of the alternatives - recoating vs. pipe replacement, must be carried-out. In our case, the costs of purchasing and laying a new pipeline are three times higher than such rehabilitation. In Service Pipeline Rehabilitation is economically convenient vs. pipe replacement in cases where application performances of at least 200 meters/day and operation pressure reductions under 15 % are possible. In case of single line natural gas transportation systems, the operational costs related to pressure reductions plays the most significant role when the rehabilitation tasks are planned. The productivity of the coating application plays a critical role in the selection of the most effective type of coating to be applied, otherwise, the costs associated with recoating could increase to such an extent to render a negative economic value compared to replacement using new pipes. The actual ambient conditions in the rehabilitation areas are critical parameters to be considered in the coating selection process. Long term rehabilitation plans, with a positive economical value compared to the pipe replacement, should be continuously generated, in order to maximize the product flow and the maximum operating pressure of the transportation system at all times.