The HAZard and OPerability technique is probably the most widely known hazard identification technique. It can be used at all stages from the concept stage to plant modifications. It consists of analyzing the system line by line on the Piping and Instrumentation Diagrams (P&IDs). A list of guidewords is applied to each line, and the consequences, safeguards and any recommendations are recorded using a HAZOP log sheet. A multidisciplinary team is used, usually with an independent (from the project) chairman.
