10 facts regarding Consequences of failure (CoF) for RBI.

Here are my 10 facts regarding consequences of failure, I am sure you have a lot more:


  1. A dictionary definition of consequence maybe, “what comes by causation or follows from logic, as a result from one’s choice or act”.

  2. Any event however can lead to a range of consequences.

  3. A consequence can be certain or uncertain and can have positive or negative effects on objectives. It can be expressed qualitatively or quantitatively and may escalate through knock-on effects.

  4. Consequence can be expressed in terms of tangible and intangible impacts. In some cases, more than one numerical value or descriptor is required to specify consequences and their likelihood for different times, places, groups or situations. Risk identification should therefore include examination of the knock-on effects of particular failures including cascade and cumulative effects.

  5. Note that an event without consequences can also known as a “near miss”, “incident”, or “close call”.

  6. The American Petroleum Institute analyse RBI consequence by studying the release of hazardous fluid which are estimated in seven distinct steps. By determining representative fluid and its properties, selecting a set of hole sizes for the escape of the fluids estimating the total amount of fluid available for release and its potential release rate, defining the type of release and hence the model the dispersion of the final phase of the fluid, i.e., a liquid or a gas.

  7. API goes on to study the effect of the post-leak (consequence) response and determines the area potentially affected by the release, relative cost of the leak, due to downtime and environmental clean-up.

  8. API 580 uses both qualitative or quantitative consequences of failure analysis and includes flammable events (fire and explosion), toxic releases, releases of other hazardous fluids, environmental consequences, production consequences (business interruption), maintenance and reconstruction impact.

  9. The European based RBI approach states that consequence of failure should be determined separately for the four elements, namely, safety, health, environment and business, and the overall consequence determined by the highest rating. It recognises that different classifications need to be balanced so that one aspect does not dominate the risk assessment. It also considers that a satisfactory consequence assessment may require the definition of a number of scenarios, e.g. small leak, large leak, full rupture and characterisation of mitigating systems such as water curtains, detection, warning systems and monitoring which is similar to the API method.

  10. The European approach to consequence analysis is considered compatible with other approaches as the overall approach is as per API or ASME and is intended broadly for similar purposes. However, while the principles are largely similar, the user is warned against expecting identical results. There are differences in detail however, that may result in significant differences when using different consequence analysis approaches on the same plant, case or system. For example, unlike most other known approaches, European approach is designed to be industry independent and provides seamless transfer between different levels of analysis (ranging from screening to detailed).

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