Inherently Safe Design (ISD) describes a broad, philosophical approach to process safety in which the focus lies on designing processes and products in such a way as to eliminate hazards completely or sufficiently minimize their magnitude so as to eliminate hazard and negate the need for elaborate safety systems incorporated in the design.
This hazard elimination or reduction is achieved through means which are inherent to process and, as such, are permanent and inseparable from it.
Besides elimination or reduction of a hazard, ISD applies to the layers of protection in place within a system such that the strength of a layer of protection can be improved by features that are permanent and inseparable from that layer.