- Through risk reduction procedures, risk can be reduced but can never be completely eliminated. The purpose of this component of risk management is to manage the risks that remain after implementation of risk control (i.e., the residual risks).
- Process risk management involves analyzing risks, determining their acceptability, and implementing risk mitigation measures where appropriate. However, risk analysis is based upon a series of assumptions and uncertainties. For example, risk analysis is likely to assume a given plant layout and design as well as certain operating procedures and certain neighboring facilities. The analysis may be based on current understanding of chemical hazards and hazard modeling methodologies, both of which are evolving.
- Managing residual risks should involve ongoing review and reconsideration of the underlying assumptions and uncertainties. Changes in these assumptions and uncertainties may change the acceptability of the risks.
- Management systems should assure through documentation of the uncertainties and assumptions, and assign responsibility for both maintaining on-going awareness of changes and for periodically initiating an active search for new information in relevant technical fields. In addition, the process safety audit program should periodically confirm the assumptions made in the risk analysis.
- Residual risk management should also include periodic review of the identified risks to assure that they have not grown to unacceptable levels. Through the introduction of new neighboring units or the development of property adjacent to the plant sire or other factors external to a specific unit, the level of risk presented by the unit may increase. The management system should prompt periodic risk analysis to confirm that residual risks are not surpassing corporate guidelines for acceptability.
- Reference: CCPS(1989) Guidelines for Technical Management of Chemical Process Safety