Dennis C. Hendershot

Inherently safer chemical process design

Inherently safer product, process and plant design represents a fundamentally different approach to safety in chemical manufacturing. The process designer is challenged to identify ways to eliminate the hazards associated with the process, rather than to develop add-on barriers to protect people from the hazards of the manufacturing process and its materials. This is best accomplished early in the product and process design cycle, but it is never too late to apply inherently safer design concepts. However, the process designer must also recognize that most processes have many hazards, and must always retain a broad perspective when evaluating options. Design alternatives which reduce or eliminate one hazard may create or increase the magnitude of others. The designer must apply good judgment and appropriate analytical and decision making tools to allow him to select the best overall process alternative, considering all of the hazards.

Incorporation of inherent safety principles in process safety management

Process safety management (PSM) deals with the identification, understanding, and control of process hazards to prevent process‐related injuries and incidents. Explicit incorporation of the principles of inherent safety in the basic definition and functional operation of the various PSM elements can help to improve the quality of the safety management effort.

An overview of inherently safer design

Inherently safer product and process design represents a fundamentally different approach to safety in the manufacture and use of chemicals. The designer is challenged to identify ways to eliminate or significantly reduce hazards, rather than to develop add‐on protective systems and procedures. In the chemical process industries, risk management layers of protection are classified as inherent, passive, active, and procedural. Inherently safer design focuses on eliminating hazards, or minimizing them significantly, to reduce the potential consequence to people, the environment, property, and business. Inherently safer design is considered to be the most robust way of dealing with process risk and can be considered to be a subset of green chemistry and green engineering. It focuses on safety hazards—the immediate impacts of single events such as fires, explosions, and short‐term toxic impacts. Many of the strategies of inherently safer design are not specific to the chemical industry, but apply to a broad range of technologies. Strategies for identifying inherently safer options are discussed, with examples. However, for most facilities, a complete risk management program will include features from all categories of layers of protection. Also, the designer must be aware that all processes and materials have multiple hazards and that there can be conflicts among the risks associated with different alternatives. Design alternatives that reduce or eliminate one hazard may create or increase the magnitude of others. Recognition and understanding of these conflicts will enable the designer to make intelligent decisions to optimize the design.

A summary of inherently safer technology

Inherently Safer Design (ISD) is an approach for making the development, manufacturing, and use of chemicals safer. This article will present a summary overview of ISD and its elements of minimize, substitute, moderate, and simplify. In addition, a life cycle approach will be shown to give the most effective use of ISD as well as other risk mitigation methods and strategies.

Implementing inherently safer design in an existing plant

Although the best time for implementation of inherently safer design alternatives is during early process development and plant design, there are often opportunities to modify an existing plant to significantly enhance inherent safety. We will describe a modification to a bromine raw material handling facility, replacing an existing bulk storage tank with cylinders. Incident consequence analysis and quantitative risk analysis were used to understand the relative inherent safety characteristics of the design options.

Advances in inherent safety guidance

The classic reference from CCPS “Inherently Safer Chemical Processes, A Life Cycle Approach”, 1st edition, 1996, was updated in 2006–2007. The goal of this book is to influence the future state of chemical process evolution by illustrating and emphasizing the merits of integrating process research, development, and design into a comprehensive process that balances safety, capital, and environmental concerns throughout the life cycle of the process. The authors hope that this book will influence the next generation of engineers and chemists as well as current practitioners and managers in the field of chemical processing.

Inherently safer design–not only about reducing consequences!

Process risk is a function of both the likelihood of occurrence of an incident, and of the consequences of the incident. There is a common perception that inherently safer design focuses solely on reducing or eliminating the consequences. However, an inherently safer design can also focus on the frequency part of the risk equation. An inherently safer design can make an incident inherently less likely to occur, although the consequences of the incident, should it occur, would be unchanged. In event tree or Layer of Protection (LOPA) terms, this may be thought of as a design modification which reduces the frequency of the initiating event, rather than improving the reliability of, or increasing the number of, layers of protection. Several examples of inherently safer designs which reduce the likelihood of an incident are discussed.

SACHE: 17 years of promoting teaching of safety to chemical engineering students

Abstract The Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChE) began the Safety and Chemical Engineering Education (SACHE) program in 1985. The objectives of SACHE are to encourage the incorporation of safety content into the chemical engineering curriculum, to develop safety content for chemical engineering courses, and to provide opportunities for faculty members to learn about process safety from industrial experts. Since 1985, SACHE membership has grown to more than 120 member schools. SACHE continues to provide course content, annual chemical process safety workshops at industrial facilities for chemical engineering faculty, and supports a number of AIChE student awards to promote safety awareness among chemical engineering students and faculty.

Expanding role of the loss prevention professional: Past, present, and future†‡

The forty years of the Loss Prevention Symposium has paralleled the careers of several of us in the loss prevention profession. During this time period, at the Dow Chemical Company, Rohm and Haas, and many chemical companies, the role of the loss prevention professional (LPP) has expanded from a concern for fire protection engineering to a more proactive concern for process hazards and process safety management. The role of the LPP has changed primarily because of lessons learned from major chemical processing incidents that have occurred. The Loss Prevention Symposium has served as a forum for discussing these incidents and related process safety technology. For example, Flixborough (1974) demonstrated the concern for large quantities of flammable material in the process. Seveso (1976) demonstrated the necessity to review processes for reactive chemical potentials. Mexico City (1984) illustrated the hazard of large inventories of flammables, the consequences of inadequate separation distances, and the need for adequate firewater supply. Bhopal (1984) clearly emphasized the need to evaluate processes for large toxic inventories that could be released and cause harm to large populations. Pasadena (1989) reemphasized the hazards of large inventories of flammables. In 2003, the U.S. Chemical Safety Board investigated several serious dust explosion incidents that have awakened industry to the hazards of combustible dusts. The March 2005 Texas City refinery explosion has highlighted concerns for facility siting and the hazards of start‐up operations. Because the root causes of all these incidents were management system deficiencies, the current role of the LPP now focuses on the evaluation of process safety management systems as well as the evaluation of process hazards. The need for a positive safety culture to successfully implement process safety management systems has recently been recognized. This article will explore the effects of major chemical incidents on the role of the LPP past, present, and future.

The Importance of Inherently Safer Processes to Site Security

Inherently safer processes (ISP) have become increasingly more important in recent years, specifically since the terrorist events of September 2001. New emphasis on site security and vulnerability has made it imperative for the chemical industry to view new and existing processes in a creative way. The tools available in designing an inherently safer process will allow industry to make these changes. “We ought, when possible, to be removing hazards rather than controlling them” (Kletz [1]). The concepts of inherent safety will be reviewed with specific examples with site security implications. For example the in-situ intermediate generation of methyl isocyanate (MIC) is a striking example of the concept of minimization and is of particular interest, since after the Bhopal incident, large quantities of MIC would be a target for terrorism. Other examples such as in-situ generation of phosgene use of aqueous ammonia instead of anhydrous, and elimination of chlorine cylinders in water treatment will be discussed with site security implications. The concepts used to create these inherently safer designs can then be integrated into existing process safety management programs to improve the overall safety of the chemical industry.Copyright