S&C presented its paper, “Incorporating Condensation and Evaporation into the Simulation of Multiphase Pipelines” at Pipeline Simulation Interest Group in May. The paper shows how S&C tackles the challenges that arise when gas/liquid phase changes occur when pipes are exposed to particularly high or low temperatures. The energy absorbed or released during the phase change will impact the temperature and pressure of the fluid. Failing to account for that impact can result in inaccurate predictions for temperatures and pressures. The formation of a 2nd phase in single-phase pipelines can also introduce slugging, interfere with the operation of the compressors/pumps, and damage the equipment that runs the pipeline. This paper describes a procedure that was developed to simulate the impact that evaporation and condensation have on the behavior of pipelines. It also discusses the results of two case studies that were performed to test the accuracy and efficiency of the new method.