An Overview of Process Hazard Evaluation Techniques

Abstract

Since the 1985 release of methyl isocyanate in Bhopal, India, which killed thousands, the chemical industry has begun to use process hazard analysis techniques more widely to protect the public from catastrophic chemical releases. These techniques can provide a systematic method for evaluating a system design to ensure that it operates as intended, help identify process areas that may result in the release of a hazardous chemical, and help suggest modifications to improve process safety. Eight different techniques are discussed, with some simple examples of how they might be applied. These techniques include checklists, "what if" analysis, safety audits and reviews, preliminary hazard analysis (PHA), failure modes and effect analysis (FMEA), fault tree analysis (FTA), event tree analysis (ETA), and hazard and operability studies (HAZOP). The techniques vary in sophistication and scope, and no single one will always be the best. These techniques can also provide the industrial hygienist with the tools needed to protect both workers and the community from both major and small-scale chemical releases. A typical industrial hygiene evaluation of a facility would normally include air sampling. If the air sampling does detect a specific hazardous substance, the source will probably be a routine or continuous emission. However, air sampling will not be able to identify or predict the location of a nonroutine emission reliably. By incorporating these techniques with typical evaluations, however, industrial hygienists can proactively help reduce the hazards to the workers they serve.

Risk assessment: methods on purpose?

“…Operationally, this leads to the systematic identification of how feared events may occur. As with a lot of other risk analysis methods, results are formalized in cause-consequence scenarios, identified safeguards and recommendations for additional barriers (Gressel and Gideon 1991) (Glossop, Loannides, and Gould 2000b) (Tixier et al 2002) (Everdij, Blom, and Kirwan 2006) (Popović and Vasić 2008). We argue that the fact that results from risk analysis from different methods are formalized in a way that looks similar (e.g.…”

“…Literature gives primarily the following differences in the methods as: (1) levels of detail of the analysis and associated project development phases (Glossop, Loannides, and Gould 2000b) (Popović and Vasić 2008), (2) inductive or deductive pathways (Hoepffner 1989) (Stephans 2012), (3) quantitative and qualitative aspects (Montague 1990) (Tixier et al 2002) and (4) the assumed adequacy of one type of industry over another (Lees 1980) (Freeman 1985) (Knowlton 1986) (Nolan 1994). It is often pointed out that a method is not in itself better than another (Gressel and Gideon 1991). Guidances also mention the need to use several methods in a complementary way.…”

“…What are the potential impacts in terms of safety (Rausand 2005b) (Smith 2001) ? The relevance of the method both as a design tool and as an aid to decision, is largely dependent on the quality of the functional analysis (Gressel and Gideon 1991).…”

Assessment of Health, Safety and Environmental Risks of Zahedan City Gasoline Stations

“…Among the benefits of this approach we can refer to its appropriateness in quantitative risk assessment and the reliability of this approach to predict problems and identify the most effective risk prevention solution [12]. FMEA is a systematic and a completely mental preventive approach based on teamwork which is used in defining, identifying, assessing, preventing, eliminating or controlling the states, causes and effects of potential errors in a system, process, project, or service (before a final product or service reaches its customer), and the prediction of errors and the way to prevent them is the prerequisite [13][14][15].…”

Comparison of Risk Assessment Using HAZOP and ETBA Techniques: Case Study of a Gasoline Refinery Unit in Iran

“…These techniques provide a systematic method of evaluating system design to ensure that it operates as intended, and help in the identification of process areas that are likely to be involved in the release of a hazardous chemical, and also in suggesting modifications that improve process safety. These techniques vary in sophistication and scope, and no single technique is likely to be the best under all circumstances [8].…”