An overview of inherently safer design


  • Dennis C. Hendershot

    Corresponding author
    1. Senior Technical Fellow, Rohm and Haas Company, Engineering Division, Croydon, PA 18925, retired
    2. Chilworth Technology, Inc., Plainsboro, NJ 08536
    • Senior Technical Fellow, Rohm and Haas Company, Engineering Division, Croydon, PA 18925
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  • For presentation at the 20th Annual CCPS International, Conference Risk Management: The Path Forward, April 11–13, 2005, Atlanta, GA.


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. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006