Many organizations in different locations with different cultures and languages participate in the construction and operation of process plants. The data generated by each stakeholder involved in the plant life-cycle are closely related to each other. Therefore, it is important to link and integrate the various data created by each stakeholder. In this study, a method of integrating plant life-cycle data, including the equipment maintenance history, was proposed based on the International Organization for Standardization 15926 standard. To this end, a data model for integrating plant life-cycle data, including maintenance, was developed using the International Organization for Standardization 15926 standard. The proposed method was validated by developing a prototype system and performing experiments converting and visualizing life-cycle data, including maintenance history in the International Organization for Standardization 15926 format, using sample data from a refinery plant.