Chemical Reactivity Hazards

Use reactor calorimetry testing to determine thermodynamics and kinetics of process. See Appendix 2A (Chemical reactivity hazards screening). 

A number of important parameters influence chemical reactivity hazards such as ... 

Introduction Chemical reactivity is the tendency of substances to undergo chemical change. A chemical reactivity hazard is a situation with the potential for an uncontrolled chemical reaction that can result directly or indirectly in serious harm to people, property, or the environment. A chemical reaction can get out of control whenever the reaction environment is not able to safely absorb the energy and products released by the reaction. The possibility of such situations should be anticipated not only in the reaction step of chemical processes but also in storage, mixing, physical processing, purification, waste treatment, environmental control systems, and any other areas where reactive materials are handled or reactive interactions are possible. 

Inherently safer facilities with respect to chemical reactivity hazards must locus on the magnitude of stored chemical energy, the kinetics of how fast the energy could be released, and the possible reaction products that may themselves have hazardous properties such as toxicity or flammability. 

Review what is known of the chemical reactivity hazards (as well as other hazards) that will need to be contained and controlled in the proposed process. This existing level of knowledge might come from past experience, suppliers, literature reviews, incident reports, etc. 

Based on the level of knowledge of chemical reactivity hazards, determine if additional screening of reactivity hazards is necessary. Having reactive functional groups might indicate the need to perform literature searches, access databases, or run differential scanning calorimetry. 

Volume 2 of Bretherick s Handbook of Reactive Chemical Hazards (Urben, 1999) lists many structures and individual chemical compounds having oxidizing properties. NFPA 432 can be consulted for typical organic peroxide formulations. Note, however, that some organic peroxide formulations bum with even less intensity than ordinary combustibles and present no chemical reactivity hazard. 

These reviews can be either in addition to or combined with periodic process hazard analyses (PHAs) by using methods such as what-if analysis and HAZOP studies. The latter should consciously focus on identifying scenarios in which intended reactions could get out of control and unintended reactions could be initiated. One means of accomplishing this as part of a HAZOP study has been to include chemical reaction as one of the parameters to be investigated for each study node. Johnson and Unwin (2003) describe other PHA-related approaches for studying chemical reactivity hazards. 

Reactive Chemistry Reviews The process chemistry is reviewed for evidence of exotherms, shock sensitivity, and other instability, with emphasis on possible exothermic reactions. The purpose of this review is to prevent unexpected and uncontrolled chemical reactions. Reviewers should be knowledgeable people in the field of reactive chemicals and include people from loss prevention, manufacturing, and research. The CCPS Essential Practices for Managing Chemical Reactivity Hazards provides a useful protocol for identifying chemical reactivity hazards (Johnson et ah, 2003). A series of questions about the chemical handling operations and the materials are used to determine if there are possible reactivity hazards. Figure 23-18 summarizes the CCPS protocol for identifying reaction hazards. 

FIG. 23 18 CCPS preliminary screening for chemical reactivity hazards. [From Johnson et al. (2003) copyright AIChE reproduced with permission. ]... 

Damaging fires are uncontrolled chemical reactions, so fire hazards involving ordinary flammable and combustible materials could be included in the above definition of chemical reactivity hazards. However, this publication seeks to supplement basic fire prevention and protection measures by addressing how to successfully manage other chemical reactivity hazards in the work environment. Consequently, the use of the term "chemical reactivity hazards" in this publication will not include explosion, fire and dust explosibility hazards involving the burning of flammable and combustible materials in air. Storage and use of commercial explosives is also outside the scope of this publication. 

Many materials in common business and household use, such as cleaners and solvents, can pose chemical reactivity hazards. The potential often exists for them to be combined with other materials with which they will... 

Chapter 3 provides a screening tool to help determine whether chemical reactivity hazards are present that need to be managed and controlled. 

The purpose of this publication is to contribute to a continued reduction in the number and severity of incidents involving uncontrolled chemical reactions in the workplace. The obj ective of this publication is to convey the essentials of managing chemical reactivity hazards—those elements that are necessary, but not always sufficient, to avoid or mitigate chemical reactivity incidents. Implementing these elements should result in a management system that will, on an ongoing basis ... 

Commit to managing chemical reactivity hazards throughout the entire facility lifetime. 

Prevent chemical reactivity incidents by designing, constructing, operating and maintaining the facility in such a way that all chemical reactivity hazards are contained and controlled. 

Somewhat different organizational structures may be needed for managing different kinds of chemical reactivity hazards. As defined in Section 1.3, three general situations involving chemical reactivity hazards are as follows ... 

Chemical reactivity hazards have been involved in some of the most severe industry incidents in history ... 

This Concept Book seeks to fulfill a need for a document that gives details of practices that are essential to safely managing chemical reactivity hazards. Although it is presented primarily in the context of the U.S. and European industrial and regulatory arenas, the practices outlined in the... 

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