Professions in the Petroleum and Petrochemical Industry (Downstream), particularly those involved in Operation, Mechanical Maintenance, Electrical Maintenance, and Instrumentation Maintenance, are key roles within the petroleum and petrochemical industrial plants. The nature of the work is complex, and therefore, workers in these areas must be eager to learn and perform their tasks correctly throughout every process. Continuous development of skills and knowledge is necessary to ensure that workers can execute their tasks without causing significant harm or damage. Currently, there is a lack of development in Occupational Standards and Professional Qualifications for personnel in this field. It is essential to foster skills development in accordance with Occupational Standards and Professional Qualifications, with competence assessments and certification of Professional Qualifications. This will lead to career advancement for the workforce and contribute to the sustainable development of personnel in the petroleum and petrochemical industry in the future. For more information about Occupational Standards in the Petroleum and Petrochemical Industry, visit: http://tpqi-net.tpqi.go.th/home/occ/industrialInfo/PTC