The chemical and process industries have been using a variety of hazard and operability problems identification techniques for many years, the most well known of which is HAZOP. HAZOP is a structured and systematic examination of a planned or existing process or operation in order to identify and evaluate problems that may represent risks to personnel or equipment, or prevent efficient operation In this paper the process control review and HAZOP study has applied for a Visbreaking plant. Before applying Hazop technique for the visbreaking unit, the plant process control was reviewed to identify design intents for all equipment in the plant, then the Hazop study for the Visbreaking Plant has conducted. The result of hazop study show that there is no deviation from the design intents for all nods (equipment) in the plant; and hence there are no Hazard or operability problems in the plant.