HAZOP – Hazard and Operability Study

A Hazard and Operability study (HAZOP) is a detailed examination of the process to review the design and operation of a process facility. The HAZOP can be thought of as a rigorous, structured analysis designed to investigate possible deviations from the design intent of the process. The procedure takes a full description of the process (usually in the form of P&IDs), systematically questions every part of the process to discover how deviations from the design intent can occur, and decides whether these deviations can give rise to hazards. The structure comes from prescribed sets of words that are combined to produce questions. This pre planned approach helps to provide rigor to the procedure by assuring that the team does not forget to ask some important question.

The focus of the questioning is moved through each and every part of the design or process. The purpose of the HAZOP questioning is to identify all possible deviations from the way the design is expected to operate and all the hazards associated with the potential deviations. In other words, a hazard is assumed to occur only if the process deviates from the design intent. If the process is operating within its design limits, then no hazard may be realized.

A HAZOP study has two major objectives:


Identify characteristics of the plant, process system, equipment, operation, or procedures that may result in a hazardous scenario.


Identify potential operability problems that make it difficult to maintain and operate the process.  These operability problems may or may not be hazardous.

Once the hazards have been identified, causes and consequences of the potential problem are considered, and recommended changes or further study items are suggested to overcome the hazard or issue.

Properly conducted Hazard and Operability studies (HAZOPs) are an integral part of any project’s successful development. This method can help determine if a designed or existing facility can be operated safely, and can identify potential operational issues. Additional concerns addressed are environmental regulation compliance, maintenance costs, and public relations effects.

Quest HAZOP methodology follows that found in US regulations for facilities with PSM requirements. In order to perform a comprehensive hazard analysis of the process and its operation, the following aspects that are described in Paragraph (e)(3) of 29 CFR 1910.119 and Paragraph (c) of 40 CFR 68.67 are considered:

The process hazard analysis shall address:

  1. The hazards of the process;
  2. The identification of any previous incident which had a likely potential for catastrophic consequences (40 CFR 68) in the workplace (29 CFR 1910.119);
  3. Engineering and administrative controls applicable to the hazards and their interrelationships such as appropriate application of detection methodologies to provide early warning of releases. (Acceptable detection methods might include process monitoring and control instrumentation with alarms, and detection hardware such as hydrocarbon sensors.);
  4. Consequences of failure of engineering and administrative controls;
  5. Facility siting (29 CFR 1910.119) or stationary source siting (40 CFR 68);
  6. Human factors; and
  7. A qualitative evaluation of a range of the possible safety and health effects of failure of controls (40 CFR 68) on employees in the workplace (29 CFR 1910.119).

For these studies, Quest provides Team Leaders (facilitators) and Scribes (recording secretaries). Our facilitators and scribes are trained on PHA software, which includes: HAZOP Manager from Lihou Technical and Software Services, PHAPro by Sphera, and exSILentia by exida. We are also familiar with several other PHA software packages and have the ability to use any of them in response to specific requests.

Our HAZOP experience covers a range of facilities from small vendor units to large facilities.

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