Hazards and Operability Analysis HAZOP

Hazard and Operability Analysis (Hazop) (Kletz, 1992) is one of the most used safety analysis methods in the process industry. It is one of the simplest approaches to hazard identification. Hazop involves a vessel to vessel and a pipe to pipe review of a plant. For each vessel and pipe the possible disturbances and their potential consequences are identified. Hazop is based on guide words such as no, more, less, reverse, other than, which should be asked for every pipe and vessel (Table 1). The intention of the quide words is to stimulate the imagination, and the method relies very much on the expertise of the persons performing the analysis. The idea behind the questions is that any disturbance in a chemical plant can be described in terms of physical state variables. Hazop can be used in different stages of process design but in restricted mode. A complete Hazop study requires final process plannings with flow sheets and PID s. 

Hazard and Operability Analysis (HAZOP) Identification of process disturbances with the quide words No, not more, less as well as part of reverse other than sooner, later other place... 

Hazard and operability analysis (HAZOP) A qualitative hazard analysis technique to identify and... 

If there is no hypothesis for the event, use an inductive method to find potential scenarios. Inductive methods speculate a given fault or failure, then look forward in time to determine the probable outcome, that is, What would happen if... Inductive methods include using a Checklist or a Hazard and Operability Analysis (HAZOP). 

Methods for performing hazard analysis and risk assessment include safety review, checklists, Dow Fire and Explosion Index, what-if analysis, hazard and operability analysis (HAZOP), failure modes and effects analysis (FMEA), fault tree analysis, and event tree analysis. Other methods are also available, but those given are used most often. 

Hazard and Operability Analysis. The hazard and operability analysis (HAZOP) procedure is quite popular because of its ease of use, the ability to organize and structure the information, minimal dependence on the experience of the analysts, and the high level of results. Furthermore, the approach is capable of finding hazards associated with the operation of a facility, hence the incorporation of the word operability in the name. 

Basically, it remains up to the design engineer and/or end user to determine whether and which type of SRV is to be used when doing a hazard and operability analysis (HAZOP). 

Chapter 3 presents introductory aspects of safety and human factors. Chapter 4 is devoted to methods considered useful to perform patient safety analysis. These methods include failure modes and effect analysis (FMEA), fault tree analysis (FTA), root cause analysis (RCA), hazard and operability analysis (HAZOP), six sigma methodology, preliminary hazard analysis (PFfA), interface safety analysis (ISA), and job safety analysis (JSA). Patient safety basics are presented in Chapter 5. This chapter covers such topics as patient safety goals, causes of patient injuries, patient safety culture, factors contributing to pahent safety culture, safe practices for better health care, and patient safety indicators and their selection. 

The hazard and operability analysis (HAZOP) technique was developed to identify both hazards and operability problems in chemical process plants. An interdisciplinary team and an experienced team leader are required. In a HAZOP application, a process or operation is systematically reviewed to identify deviations from desired practices that could lead to adverse consequences. HAZOPs can be used at any stage in the life of a process. 

Where multiple, diverse hazards exist, the practical approach is to treat each hazard independently, with the intent of achieving acceptable risk levels for all. In the noise and toluene example, the hazards are indeed independent. In complex situations, or when competing solutions to complex systems must be evaluated, the assistance of specialists with knowledge of more sophisticated risk assessment methodologies such as Hazard and Operability Analysis (HAZOP) or Fault Tree Analysis (FTA) may be required. However, for most applications, this author does not recommend that diverse risks be summed through what could be a questionable methodology. 

There are many hazard analysis formulations which may be used effectively to assess process hazards. These include fault-free analysis, failure mode and effect analysis (FMEA), what-if analysis, hazard and operability analysis (HAZOP), check list analysis, and safety review, among others. The specifics associated with these analyses can be reviewed by consulting the appropriate American Institute of Chemical Engineers Center for Chemical Process Safety reference. " ... 

Other methods such as Failure Mode and Effects Analyses (FMEA) and Hazard and Operability Analysis (HAZOP) were developed not just to analyse possible causes of hazards (and, later on, causes of accidents), but also systematically to identify hazards and risks before a system was taken into operation or when a major change was considered. 

The second and much more detailed step was a HAZard and OPerability analysis (HAZOP). (A detailed description of this method can be found in [5], too.) Each node... 

Hollnagel uses the term requisite imagination, based on the concept requisite variety from cybernetics and control theory, about the ability to speculate constructively about the possible ways in which something can go wrong (Hollnagel 2004, pp 182). Hazard and operability analysis, HAZOP, is a technique... 

There are many well-established and proven ways of conducting a hazards analysis. Atone extreme as simple and relatively unstructured methods such as a Major Hazards Analysis. At the other end of the spectrum lie highly organized methods such as Hazard and Operability Analysis (HAZOP) and Layers of Protection Analysis (LOPA). 

---