Inherently Safer Design Conflicts and Decisions
John Murphy (United States Chemical Safety and Hazard Investigation Board, retired)
Inherently Safer Design (ISD) is a different philosophy for addressing safety issues in the design and operation of chemical plants. ISD focuses on eliminating or significantly reducing hazards. Often, the traditional approach to managing chemical process safety has accepted the existence and magnitude of hazards in a process, and efforts to reduce risk have concentrated on managing the risk associated with the hazards. Where feasible, ISD provides more robust and reliable risk management, and has the potential to make the chemical processing technology simpler and more economical in many cases.
However, it is important to recognize that any change to a technology or product, even a change intended to enhance safety, has the potential to introduce new hazards and risks, and to increase the magnitude of existing hazards and risks. It is important to recognize this potential and fully evaluate any change in technology with regard to all hazards and potential risks. Thus, a process or product which is inherently safer with respect to one or more hazards may introduce new risks, and these must be considered in choosing the appropriate process technology. This module describes these issues with respect to ISD, with examples of ISD conflicts. Once the potential conflicts are understood, the problem becomes a traditional engineering optimization problem, with the objective of selecting a technology option which generates the greatest overall value considering all of the conflicting requirements.
The basic principles of Inherently Safer Design (ISD) are covered in more detail in the SACHE module “Introduction to Inherently Safer Design”, distributed to SACHE members in 2006 and available for download by SACHE members on this site.
Spanish translation: Available for one or more files.
Student access: All files are available to students logged into the site.