The realization of PHA (Process Hazard Analysis) as an evaluation of all those elements that are part of management programs for safety in industrial processes that can generate an impact on the profitability of the company, is a matter to highlight. Given the above, industries need to identify the variations that occur concerning normal parameters in the process. During the development of the study, operational risks are analysed in the process of a dairy plant, located in Cundinamarca, Colombia. For this analysis, the HAZOP methodology is used, which will allow the identification of hazards, operability study, and mitigation of the risks related to the investigated process. For the analysis, the pasteurization and mixing stage as the subsystem was determined. In this operational stage, the node to study was the reactor. The different diagrams of the node for the analysis were established. The specifications at the equipment and instrumentation level were used. Previous information, plus the contributions regarding the operation of the plant by staff, the inputs are compiled for the development of the mentioned methodology. Once the deviations in the studied node were identified, the possible origins and effects of each deviation were determined. The measures and corrective actions necessary for improvements in the production process were proposed.