In this paper the concepts of maintenance and remodeling in general have been clarified and analyzed, and then elaborated on a concrete example of refining of the oil refinery in Rijeka. The first part of the paper gives a brief overview of the company „Monter – Strojarske montaže d.d.” which has a strong market position in the installation and repair of oil and gas power plants, and are regularly present at the maintenance and refurbishment of the Rijeka Oil Refinery. As an introduction to the topic of renewal of the oil and gas power plants, a description of the maintenance concept, the type of overhaul and all the parts that must be taken into account in some renovation have been made. For the oil refinery in Rijeka, the historical development has been made since its launch in 1883 until today. Production process of Oil Refinery Rijeka is divided into groups of plants. Each group of plants encompasses different processes of oil refining, and for that reason, a brief description of these processing processes has been made. For the described refinery, a detailed overhaul plan with basic information and a description of jobs and projects has been elaborated in detail and the resources required for the design of such a demanding overhaul have been analyzed. This is the biggest overhaul in the history of INA and the Oil Refinery in Rijeka, in which INA invested around 800 million Kuna this year. The Refurbishment Plan for the Oil Refinery in Rijeka was created using selected software support. First, an analysis of all the necessary jobs, resources and overhaul documentation is carried out. Defining the overhauling activities, length of service - required working hours, required tools and materials, required workers, required spare parts and components, and the like. The whole set of information and experience in making it greatly affect the final result. The goal is always to extend work ability, reliability and efficiency. The remittance activities are then performed by methods according to the predetermined documentation. Part of the documentation of the overhaul plan will be shown below in the work through the attachments of the image and the list of activities of the work.