Hazard and operability study

A hazard and operability study (HAZOP) is a structured and systematic examination of a complex system, usually a process facility or machinery, in order to identify hazards to personnel, equipment or the environment, as well as operability problems that could affect operations efficiency. It is the foremost hazard identification tool in the domain of process safety. The intention of performing a HAZOP is to review the process or machinery through all phases of the product lifecycle to pick up design and engineering issues that may otherwise not have been found in other hazard identification (risk assessments) or design tools (FMEA’s, FTA’s, etc.)

The technique is based on breaking the overall complex design of the process into a number of simpler sections called nodes which are then individually reviewed. It is carried out by a suitably experienced multi-disciplinary team (roles defined in section below) during a series of meetings. The HAZOP technique is qualitative and aims to stimulate the imagination of participants to identify potential hazards and operability problems. Structure and direction are given to the review process by applying standardized guideword prompts to the review of each node. A relevant standard IEC 61882 calls for team members to display 'intuition and good judgement' and for the meetings to be held in "an atmosphere of critical thinking in a frank and open atmosphere [sic]."

The HAZOP technique was initially developed for systems involving the treatment of a fluid medium or other material flow in the process industries, where it is now a major element of process safety management. It was later expanded to the analysis of batch reactions and process plant operational procedures. Recently, it has been used to assess domains other than or only loosely related to the process industries, namely: software applications including programmable electronic systems; software and code development; systems involving the movement of people by transport modes such as road, rail, and air; administrative procedures in different industries; medical devices; machinery; etc.