Maintaining adequate air cycle with desired quality and purging ambience from potential toxic, dangerous and ignitable gases, are among the most important actions taken toward the improvement of safety in a process unit. In modern industrial environments, high-quality air and sufficient air conditioning within a plant are vital when it comes to area classification. This project investigates and analyzes gas dispersion and air ventilation within an offshore platform using computational fluid dynamic, which is more complex than onshore plants. This method and its idea could be utilized in any risky environment (such as process plants, factories, warehouses, etc.), whether it's an offshore or an onshore plant. To better assess the data, simulations of possible hazardous events and solutions for preventing or reducing their probability of occurrences are presented as well. These investigations are done by considering on hypothetical scenarios which consist of gas leakages from pipelines and process equipment in different conditions. Using CFD simulation results, gas behaviors, dispersion, distribution, accumulation and possible hazards are investigated and analyzed by utilizing a precise and detailed CAD model of the environment. Moreover the probability of inducing ignitable or toxic concentration of gases within the atomsphere and air ventilation of the unit is considered by these investigations. PDMS, rhinoseros, harpoon and ansys CFX are used software in the project.‎