Qualitative answers to one or more of these questions are often sufficient for making good decisions about the allocation of resources for safety improvements. The extent of risk assessment and the degree of risk understanding that is needed may vary. It uses a set of highly sophisticated, but approximate, tools for acquiring risk understanding. Back to Top When to Use the QRA Techniques Figure 2 is an example of a decision tree that may be useful to managers when they are considering using QRA techniques for particular safety applications. European processes may have other QRA requirements.
Most chemical processes require a PHA, using qualitative techniques.
If the study is being performed to address safety issues and the hazard is not considered to be major, a QRA is generally not necessary. Generally, if a specific process or several processes spread throughout an organization are well established, the need for quantified frequency information is reduced. The theory is that with a large experience base, you should have a better understanding of the risks associated with your process, and the need for a QRA is reduced. Basically, these steps are a qualitative judgment of the perceived level of risk associated with the process. A judgment can sometimes be made that the potential consequences from an accident involving the process are known and are acceptable.