Processing methods checklist

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

For slightly more complex processes, the checklist method provides a more organized approach (2). This is accomplished by the use of lists of words or phrases that will stimulate questions concerning the subject. For example, the phrase Personnel Protection should lead to questions relating to the adequacy of ventilation and toxicity of the chemicals used. There are a number of checklists available in Du Pont, each applicable to the site or department for which it was written. Assignments of certain aspects of the project under review can be made to committee members who have the greatest expertise in that area. 

The Checklist Method uses a set of prewritten questions to stimulate discussion and thinking, often in the form of a What-If discussion. The questions are developed by experts who have conducted many hazards analyses and who have extensive experience to do with the design, operation, and maintenance of process facilities. Checklists are not comprehensive—no hazards analysis method can make that claim. Nevertheless, they should make sme that a complete range questions is asked and that nothing that would be regarded as obvious is overlooked. 

Process Hazards Analysis. Analysis of processes for unrecogni2ed or inadequately controUed ha2ards (see Hazard analysis and risk assessment) is required by OSHA (36). The principal methods of analysis, in an approximate ascending order of intensity, are what-if checklist failure modes and effects ha2ard and operabiHty (HAZOP) and fault-tree analysis. Other complementary methods include human error prediction and cost/benefit analysis. The HAZOP method is the most popular as of 1995 because it can be used to identify ha2ards, pinpoint their causes and consequences, and disclose the need for protective systems. Fault-tree analysis is the method to be used if a quantitative evaluation of operational safety is needed to justify the implementation of process improvements. 

More shortcut design methods and rules of thumb have been developed for fractionation than probably any other unit operation. For example the paper reprinted in Appendix 5 on development of shortcut equipment design methods contains 18 references for fractionation shortcut methods out of 37 total. Both the process and mechanical aspects of fractionation design have useful rules of thumb. Many of the mechanical design rules of thumb become included in checklists of do s and don ts. 

Included in OSH As JHA Booklet, 3071, is a good description of a process hazard analysis (PHA) [1]. This is being used in the Process Safety Management (PSM) program (29 CER 1910.119) to understand how hazards exist. There are some good methods listed in the manual that can be used to conduct a JHA. As you review each method you can determine which one may be useful for your operation. The typical method chosen is the checklist. 

What-ll/Checklist combines the creative, brainstorming features of a What-lf with the systematic features of a Checklist. The What-lf analysis considers accidents beyond the checklist the check list lends a systematic structure to the What-lf analysis. A What-lf7Checklist examines the potential consequences of accident scenarios at a more general level than some of the more detailed I l liA methods. It can be used for any type of process at any life cycle stage. 

Combining the What-If and Checklist analysis methods uses their positive features while compensating for their separate shortcomings, For example, a checklist is hascti on generic process experience and may i.i c incomplete insights into the design,... 

Although checklists are a useful way of transferring information about human-machine interaction to designers and engineers, they are not a standalone tool and they cannot provide a substitute for a systematic design process. The main concern with checklists is that they do not offer any guidance about the relative importance of various items that do not comply with the recommendations, and the likely consequences of a failure due to a noncompliance. To overcome such problems, checklists should be used in combination with other methods of task analysis or error analysis that can identify the complexities of a task, the relationships among various job components, and the required skills to perform the task. 

Hazard or event identification provides information on situations or chemicals and their releases tliat can potentially hanii tlie emaromiient, life, or property. Inforniation that is required to identify hazards includes chemical identities, quantilics and location of chemicals in question, chemical properties such as boiling points, ignition temperatures, and to.xicily to hmnans. There arc sci cral nictliods used to identify hazards. The methods that will be discussed later in tliis Part w ill include tlie process checklist and tlie hazard mid operability study (HA20P). 

The checklist analysis method is versatile, easy to use and can be applied at any stage in the life of a process. It is primarily used to indicate compliance with standards and practices. It is also a cost-effective way to identify common and customarily recognized hazards. 

A traditional checklist analysis uses a list of specific items to identify known types of hazards, design deficiencies, and potential accident scenarios associated with common process equipment and operations. The method can be used to evaluate materials, equipment, or procedures. Checklists are most often used to evaluate a specific design with which a company or industry has a significant amount of experience, but they can also be used at earlier stages of development for entirely new processes to identify and eliminate hazards that have been recognized through operation and evaluation of similar systems. To be most useful, checklists should be tailored specifically for an individual facility, process, or product. 

The what-if/checklist analysis method combines the creative, brainstorming features of the what-if analysis with the systematic features of the checklist analysis. The PrHA team uses the what-if analysis method to brainstorm the types of accidents that can occur within a process. Then the team uses one or more checklists to help fill in any gaps. Finally, the team members suggest ways for reducing the risk of operating the process. The what-if analysis encourages the PrHA team to consider potential accident events and consequences that are beyond the experience of the authors of a good checklist and, thus, are not covered on the checklist. Conversely, the checklist lends a systematic nature to the what-if analysis. 

For example, a traditional checklist is, by definition, based on the process experience the author accumulates from various sources. The checklist is likely to provide incomplete insights into the design, procedural, and operating features necessary for a safe process. The what-if part of the analysis uses a team s creativity and experience to brainstorm potential accident scenarios. However, because the what-if analysis method is usually not as detailed, systematic, or thorough as some of the more regimented approaches (e.g., HAZOP study, FMEA), use of a checklist permits the PrHA team to fill in any gaps in their thought process. 

The number of individuals needed depends upon the complexity of the process and, to some extent, the stage at which the process is being evaluated. Normally, a PrHA using this method requires fewer people and shorter meetings than does a more structured method such as a HAZOP study. Estimates of the time needed to perform a PrHA using the what-if/ checklist analysis method are shown in Table 4.11. 

V Process hazard analysis (PHA) must be performed by a team of experts, including engineers, chemists, operators, industrial hygienists, and other appropriate and experienced specialists. The PHA needs to include a method that fits the complexity of the process, a hazards and operability (HAZOP) study for a complex process, and for less complex processes a less rigorous process, such as what-if scenarios, checklists, failure mode and effects analysis, or fault trees. 

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). 

A series of checklists is proposed to avoid such incidents in chemical processing operations, and an incompatibility chart for groups of reactive chemicals is given. The methods used for the analysis of the case histories are detailed in a separate... 

This chapter addresses methods and tools used successfully to identify multiple root causes. Process safety incidents are usually the result of more than one root cause. This chapter provides a structured approach for determining root causes. It details some powerful, widely used tools and techniques available to incident investigation teams including timelines, logic trees, predefined trees, checklists, and fact/hypothesis. Examples are included to demonstrate how they apply to the types of incidents readers are likely to encounter. 

If the deductive process has stalled and no further progress seems possible or likely, then the iterative loop calls for application of inductive investigation methods such as a checklist or HAZOP. The inductive methods may also benefit from use of the fact/hypothesis matrix tool described in this chapter. 

The checklist is divided into three areas 1) Material Storage and Handling, 2) Production Processes and 3) Treatment Alternatives. Material degradation, samples, spills, storage, and inspections are addressed in the first section. Production processes include source reduction for process bath solutions and rinse systems, resource recovery and recycling, and solvent management. Treatment Alternatives focuses on process water pretreatment, modification of conventional wastewater treatment, and alternative waste treatment methods. Each of these subsections follow the question and answer format. 

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. 

What If/Checklist. The most frequently used method of process hazard review, the what if/checklist, is effective in reviews of relatively uncomplicated processes from raw materials to final product. The team formulates and answers What if questions at each handling or processing step to evaluate the effects of component failures or procedural errors. They use a checklist to ensure that all important subjects are addressed. This method should be used as the first step in all process hazard reviews. 

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