In this subpage, you will know what contingency is, why it is required to analyze contingency, who calls for the contingency analysis, and the thought process behind it.

If I were asked what the most important aspect of process safety is to ensure the life of equipment and personnel, I would point to contingency analysis.

1. A contingency is a possible event which can lead to equipment damage, hurt personnel, or cause environmental pollution.
2. The contingency analysis may be required at many stages of a project starting from the initial scope to the final decommissioning of the plant.
3. API -521 has a list of 18 contingencies that should be considered for handling materials that are thermally stable.
4. For materials that reactive or thermally unstable, additional 10 contingencies should be considered.
5. There are extraordinary contingencies, such as Tsunami, earthquake, flood, cyber-attack, flash-fire, tornadoes, hurricanes, etc. that should also be considered.

The risk associated with a contingency must be evaluated by its probability of occurrence multiplied by the cost of its management during Process Hazard Analysis (PHA) which is done prior to the contingency analysis. A corporation minimizes risk to a level where it can be profitably managed. Safety is a virtuous business value!

The contingency analysis typically results in additional safeguards including relief devices and, in some cases, safety instrumented system.

The documents necessary for the contingency analysis are physical location of the plant, Process Flow Diagram. Utility Flow Diagram, environmental protection system, Piping and Instrument Diagram, equipment information, layout (plan and elevation), piping isometric, operating procedure including shift-change information exchange protocol, and safety-culture. Despite our best efforts, Mother Nature has a way to “Align the Swiss Cheese Holes” for accident propagation.

The party, HAZOP group, responsible for calling for a contingency analysis is the owner of the process following the principle of Management of Change (MOC). The Head of Engineering and/or Mechanical Integrity Department help the owner of the process in the contingency analysis.

To know more about the contingency analysis, please write to Dilip K. Das at [email protected], or call him at 1(816)400 3238, or buy Emergency Pressure Relief System Design, authored by Dilip Das, published by AIChE/Wiley through Google search.