What if Method

This method is also frequently applied, although not much has been published about it in the literature. The reason for this fact most probably is that it does not belong to the systematic methods. 

It investigates certain hazards which are more or less obvious due to substance properties or process conditions. Examples are the handling of highly flammable liquids, process steps under vacuum or, the reverse, under high pressure. A group of coworkers, which at all events should be interdisciplinary, tries to anticipate all possible process or plant conditions in a kind of brainstorming approach by asking the what if question. Then the team evaluates the effects. 

The quality of the method depends almost totally on the practical experience and training of the individual members of the team. If experienced operators and representatives of the different techniced faculties of interest belong to the team and they are already familiar with the technique, then it can be of tremendous value. It is the first of the methods mentioned so far which allows for the consideration of interactions of numerous components in the complexity of a system. This way complete event paths may be analyzed. 

Another advantage of this method lies in the fact that it may also be applied to existing plants or processes. The effort for its use is somewhat larger than for checklists and depends individually on the niunber of possible hazards to be covered. 

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The What if..method, the checklist, and HAZOP are well-publicized hazard identification tools. CCPS (1992) presents guidance on the use of these tools. 

Process hazard analysis (PHA) Any of a number of techniques for understanding and managing the risk of a chemical process or plant. Examples of PHA techniques include HAZOP, checklists, what-if methods, fault tree analysis, event tree analysis, and others. 

What-if At each process step, what-if questions are formulated and answered to evaluate the effects of component failures or procedural errors. This technique relies on the experience level of the questioner. What-if methods are often used in conjunction with checklists (HEP Chaps. 4.5, 4.6, 6.5, 6.6, 12, 20). 

Earlier method of identifying hazards involved a procedure consisting of asking questions such as what if This approach consists of questioning the proper function at every stage of the process, along with consequences or the remedial features. A checklist for the simplified process hazard analysis by the what if method is shown in Table 3.3. Although this method is an old method of hazard analysis compared with other methods such as hazop or fault tree analysis it has proven to be quite useful. 

Table 3.3 What if method checklist for simplified process hazard analysis6 (Courtesy of the American Institute of Chemical Engineers)...

Both the HAZOP and What-If methods have limitations and advantages. Listed below are a brief description of these. 

It has been found that the What-If style of process hazard analysis is a convenient method to use for a "simple" facility. For simple facilities, the detailed HAZOP approach has been found to be tedious and just as productive as a What-If method. The What-If approach stimulates generation of new ideas and discussion to cover issues associated with the items under review, as well as addressing generic issues. The specific HAZOP review is not necessary when the process is simple and well understood by the reviewing team. The team can readily review the major items of concern by asking What-If questions such as what happens when a pump fails, without relying on itemized and detailed variations of a process condition by the HAZOP method, such as high level, low pressure, etc. 

If doubt exist as to what method to apply, the HAZOP method should be chosen over the What-If method. The What-If approach relies on the team leader to ferret out the real hazards associated with the process. The systematic HAZOP approach will examine each portion of the system to determine hazardous conditions. 

Appendices D and E provide further typical in-depth listings of potential causes when using HAZOP or What-If methods). 

As can be seen, in batch operations, the "What if " method is most commonly used, with the Checklist and Failure Mode Effect... 

A brief comparison between the traditional methods (such as the "what if" method) and HAZOP study is given in Table I. 

What-if method, hazard and operability (HAZOP) study, failure mode and effects analysis, and fault tree analysis. 

First, the importance of learning lessons from past process safety incidents is highlighted in Section 3.2. The subsequent section presents preliminary hazard review procedure, risk matrix, what-if method, plot plan and layout review, pressure relief system review and fire safety design aspects. Section 3.4 presents PHA techniques and procedures hazards and operability analysis (HAZOP), failure modes and effects analysis (FMEA), instrumented protective system (IPS) design, fault trees, event trees, layer of protection analysis (LOPA) and finally SIS life eyele. The importanee of revision of PSI is highlighted in Seetion 3.5. 

A what-if/checklist hazard analysis technique combines the creative, brainstorming aspects of the what-if method wiA the systematic approach of the... 

What-lf Hazard Analysis. This hazard assessment method utilizes a series of questions focused on equipment, processes, materials, and operator capabilities and limitations, including possible operator failures, to determine that the system is designed to a level of acceptable risk. Users of the What-If method would identify possible unwanted energy releases or exposures to hazardous environments. Bulletin 135 contains procedures for use of a What-If checklist. For some hazards, a What-If checklist will be inadequate and other hazard analysis methods may be used. 

HazOp studies are formal procedures used to identify and analyze hazards in a chemical operation. like the "What-If" method, HazOp is inductive in its application, and it requires a full set of P lDs and equipment specifications. 

The What-if method is the simplest method to assess chemical process safety risks and is based on questions such as What if the mechanical or electrical integrity of the process, the control systems and work procedures all fail,. .. what consequences could arise in the worst case While the potential consequences are largely determined by the inherent hazard of the material and the quantity involved, the reviewer is focused on safety concerns, e.g. those arising from fire, explosion, toxic gas release, and environmental protection. 

The assessment of impacts of traffic accident involving the oil products is performed by the What, If method that is specially modified for the safety management of the territory (Prochazkova 2011b). The results of the evaluation are listed in Table 1. 

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