ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies. The main task of ISO is to prepare International Standards. ISO 31000 provides principles and generic guidelines on risk management. This International Standard can be applied to any type of risk, whatever its nature, whether having positive or negative consequences.
ISO31000 can be used to describe the process of using HAZID outcomes (5.4.2) as input for creating bowtie diagrams (5.4.3).
ISO31000 - Managing Risk process
Risk identification is the process of finding, recognizing and describing risks. The aim of this step is to generate a comprehensive list of risks.
A HAZID study is one of the best known methodologies for doing Risk identification.
Risk analysis involves developing an understanding of the risk. Risk analysis involves consideration of the causes and sources of risk, their positive and negative consequences, and the likelihood that those consequences can occur. The analysis can be qualitative, semi-quantitative or quantitative, or a combination of these, depending on the circumstances.
The Bowtie methodology fits seamlessly in the (qualitative) risk analysis stage of the ISO 31000 managing risk process.
It is not possible to make bowtie diagrams for all existing hazards. There are simply too many hazards, and it will take too much time to make as many bowtie diagrams. Moreover, it is less beneficial to create a bowtie diagram for simple or low impact hazard, because structuring these hazards (by making bowtie diagrams) will not provide a much better understanding of the hazard (assuming these hazards will have a relatively simple structure). Therefore a separation should be made between high priority hazards that require bowtie analysis and low priority hazards for which only a HAZID analysis is sufficient. The HAZIDs inherent risk assessment levels can be used to assess which hazards require closer examination by creating bowtie diagrams.