The selection of Gas Turbines requires the evaluation of many criteria. First cost is important however the long term cost of ownership requires we look at installation cost, fuel cost and the cost of operation and maintenance. On a recent project for a pipeline in Mexico CFE was looking for someone to build own and operate a pipeline for 25 years. The flow varied a great deal and increased gradually over time so part load fuel consumption and flow flexibility were also important. In this paper we will review how evaluations were made and discuss some technical solutions which allowed the owner to achieve greater flow flexibility. Although industry standards exist for fuel consumption, compressor power requirements and available turbine horsepower suppliers do not always provide consistent values for these important pieces of information. It is important to understand the differences between expected and guaranteed values. We must also be clear about whether guarantees are for part load conditions or only valid for full power. Finally we must understand tolerances allowed in common industry standards such as API 616, API 617 and the ASME power Test Code. (ISO references will be provided) Only when all of these items are understood can the user understand the real long term cost of ownership. Content: 1. Project Overview 2. Technical solution Compression 3. Evaluating fuel costs 4. Deciding the best number of units 5. Advantages and limitations of Field Testing