Abstract
An ontology for representing operating, safety and control procedures is proposed in this paper that descibes the procedure steps and their connections, and enables to represent exceptions during the normal flow of execution in terms of time-out and failed conditions. The procedure ontology is defined within interconnected components of the process plant and the diagnostic analysis based on risk assessment information, and has been implemented as an integrated ontology in a diagnostic framework using the the Protégé ontology editor. A novel diagnostic method based on following these procedures and combining observed malfunctions with Failure Mode and Effects Analysis (FMEA) information is also proposed. The proposed ontology and the diagnostic method are illustrated on a simple operating procedure.