Inherently safer design (ISD) is a philosophy for addressing safety issues in the design and operation of facilities that use or process hazardous chemicals. When considering ISD, the de-signer tries to manage process risk by 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 incorporated engineering and administrative controls to reduce process risk. Where feasible, ISD provides more robust and reliable risk management, and has the potential to make the chemical processing technology simpler and more economical by eliminating the need for expensive safety systems and procedures.
However, when one considers the multiple risks associated with any technology, including chemical processing, it is unlikely that any process or plant design can eliminate all hazards and risk. A combination of ISD, engineering and administrative controls will always be required to adequately manage all process risks.
ISD addresses the immediate impact of single events (chemical accidents) on people, the environment, property and business. In a chemical processing plant, this generally means the immediate impacts of fires, explosions and the release of toxic materials. In many cases, an ISD also will be beneficial for other types of process risk, such as environmental risk, chronic health risk, or risk to consumers or product users. However, this is not always true. For example, a non-flammable sol-vent may be inherently safer in terms of fire and explosion risk, but it may be a serious environmental contaminant or it may pose a chronic health hazard.
While engineers recognize the potential benefits of ISD in managing other types of process risk, the main intent of ISD is to reduce the frequency and potential impact of chemical plant incidents---fires, explosions and acute toxic exposures. Therefore, application of ISD is one consideration in the selection of process and product technology, but the decision about what technology option is best overall must consider all risks.