A fully-compositional tool for modeling systems exhibiting two-phase (gas-water) flow is presented. The tool couples complex hydrodynamic and thermodynamic models to describe the behavior of fluids flowing in a pipe. The model is capable of predicting water condensation in the pipe, estimating pressure/temperature profiles, and handling different flow patterns and their transitions. The model also has the capacity of estimating the concentration of hydrocarbons, CO2, H2S, methanol, and other substances dissolved in the aqueous phase. Hydrate formation is related to the presence of methane, ethane, propane, butanes and nitrogen in a gas stream, while acid is expected to form when significant amounts of CO2 or H2S are present in the aqueous phase. The model provides production engineers with an excellent tool for evaluating the potential formation of hydrates and/or acids in piping systems. The tool will give production engineers detail that will help designing, operating, and maintaining such systems.