Hydrate formation in refinery gas pipelines is one of the major problems of refinery gas companies. There are a large number of investigations about this phenomenon. The neccessity of facing this problem has been considered in many cases. Some chemical methods and technologies have been used in order to inhibit the hydrate formation in pipelines or to predict it. In this study, a computational fluid dynamic (CFD) modeling was employed to predict the probability of hydrate formation in the gas pipeline. The proposed model was validated using the operational data of Ilam refinery gas pipeline. The pipeline was simulated and the results were compared with the experimental data. The obtained numerical results showed enough agreement with the experimental data. Regarding pressure gradient in the pipeline, hydrate formation temperature was calculated and the possibility of hydrate formation in the pipeline was evaluated according to the comparison between the hydrate formation temperature and the actual temperature. In addition, various parameters such as inlet temperature, ambient temperature, and gas flow rate were studied in order to find the hydrate formation probability using the sensitivity analysis method. Results showed that the inlet and ambient temperatures are usually higher than the hydrate formation temperature, so the probability of hydrate formation is low in the pipeline. Moreover, the results clearly showed that increasing the gas flow rate or decreasing the gas inlet temperature can increase the probability of hydrate formation in the pipeline.