Process safety has a high priority in the chemical industry. And the distillation is the most widely used unit operation in the chemical-processing industries. The use of dynamic simulation for safety-related studies for a distillation column has great significance for the study of operational failures. In this article, a systematic framework based on Extended Hazop and Event-tree analysis is applied to a distillation column unit of a chemical plant. Over pressuring of column is studied and different safety system alternatives are generated and evaluated using Event-tree analysis. This article describes the details of an effective method used for a distillation column but it can also be used for other hazardous unit operations.