HAZOP procedure

Hazard and Operability Analysis. The hazard and operabihty analysis (HAZOP) procedure is quite popular because of its ease of use, the abihty to organize and stmcture 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 faciUty, hence the incorporation of the word operabihty in the name. 

The HAZOP procedure, performed by committee, is mostiy an organizational one. There is Httie technology associated with the process. The HAZOP approach is capable of identifying hundreds of items for a reasonably complex process. This information must be organized and managed properly. 

The HAZOP committee must be composed of people with specific experience related to the process at hand. The chair, or faciUtator, responsible for managing the committee should be highly familiar with the HAZOP procedure and should have excellent committee management skills. This person must ensure that the discussion is focused and productive, and then oversee the paperwork and progress of the work. 

Table 1. List of Guide Words for HAZOP Procedure ...

A reactor system is shown in Figure 2 to which the HAZOP procedure can be appHed. This reaction is exothermic, and a cooling system is provided to remove the excess energy of reaction. If the cooling flow is intermpted, the reactor temperature increases, leading to an increase in the reaction rate and the heat generation rate. The result could be a mnaway reaction with a subsequent increase in the vessel pressure possibly leading to a mpture of the vessel. 

Continuous flow With continuous flow operations consider (e.g. using a HAZOP procedure) the effects of No flow Reduced flow Reverse flow Increased flow Contaminated flow Flow of a substituted material, etc. 

List of guide words used for the HAZOP procedure... 

The HAZOP procedure uses the following steps to complete an analysis ... 

Table 10-3 Guide Words Used for the HAZOP Procedure...

An important part of the HAZOP procedure is the organization required to record and use the results. There are many methods to accomplish this and most companies customize their approach to fit their particular way of doing things. 

RMP Hazard Review Checklists, What-lf Questions, and HAZOP Procedures... 

Hazard and Operability Study (HAZOP). The HAZOP procedure systematically questions every part of a process to discover how deviations from the intention of the design can occur, and to determine if the consequences of such deviations are hazardous. 

Andow, P. (1991), Guidance on HAZOP Procedures for Computer Controlled Plants, Her Majesty s Stationery Office, London. 

Figure 4. HAZOP procedure implemented in the knowledge-based system.

In the standard guidelines regarding the use of HAZOP in various phases of life cycle, the preparatory phase and procedure, along with various guide words and their associations with various elements, have been detailed. Flow charts are presented as examples for guidance. Use of HAZOP in various industries has been detailed in the appendix of the standard. HAZOP procedure in line with the standard is presented in Fig. VI/2.3-1 (see also Fig. 1 of standard). 

See, e.g. P.Andow, Guidance on HAZOP procedures for computer-controlled plant, HSE Contract Research Report No 26/1991 andD.J.Bums R.M.Pitblado, A modified HAZOP methodology for safety-critical system assessment mDirections in safety-critical systems,... 

The HAZOP team follows Figure 6.1, the HAZOP procedure, and Table 6.1, a list of HAZOP guide words, for each node in the system. The team starts with an input into the node by selecting a feed line. Then each of the guide words is applied to the flow fine. For example, is more flow possible If not, then go on to the next deviation. If more flow is possible, then is it hazardous If not, return to investigating the other causes of more flow. 

FIGURE 6.1 HAZOP procedure. (From Kletz, T.A., Hazop and Hazan, Identifying and Assessing Process Industry Hazards, 3rd edn., Hemisphere, Bristol, PA, p. 9, 1992. With permission.)... 

The HAZOP procedure is a powerful tool for hazard analysis and its methodical approach ensures that weaknesses in the design intent are detected and acted upon. HAZOP is widely used in RBI processes. It is also applied at an early design stage through corrosion-risk assessments as a documented process for materials selection and corrosion prevention. The strengths of HAZOP are [10]... 

In order to compare the results of LARA with well-established risk management methods, two examples were selected one from the University of Pardubice and one from EPFL. To have a variety of laboratory tasks, both chemical experiments and routine tasks were considered in the comparison. The first example was analyzed using the LARA method and a HAZOP procedure, whereas the second example was analyzed using the LARA method and the FMECA procedure. Both of these risk analysis procedures are widely acceptedtools to identify and manage risks (Bluvband et al. 2004). 

The joint tests described in this article are performed under conditions that simulate the environment for which the method is intended. The risk evaluations were performed and guided by a group of scientists, being familiar with the methods and having experience in performing FMECA and HAZOP procedures. For the LARA method, those scientists had a short introduction, but no information about the principles of the method. This was intended, since non-experts are the designated users of the LARA method. The scientists involved in the experiments provided the analysts with all information necessary, including details about the laboratory environment. 

The system definition of the WMH Biochemistry laboratory was produced in the form of sample flow diagrams, data flow diagrams, hardware interconnections and descriptive text. Each activity was reduced to small functional component, which in turn became the substrate for the FMECA and the HAZOP procedures. 

Conventional HAZOP procedures [CIA 90] are regarded as insufficient to address many potential problems of PES. They can, however, be made effective with a number of extensions, the total comprising three stages ... 

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