HAZOP parameters, deviations, and possible causes

Appendix E HAZOP Parameters, Deviations, and Possible Causes... 

The following are typical guideword parameter, deviations, and possible causes that are used in HAZOP reviews. This listing is by no means exhaustive and each review should be supplemented or tailored to meet the needs of a particular facility. 

Sometimes referred to as energy flow analysis, HazOps is used primarily in the petrochemical industry. It uses a multidisciplinary team similar to a system safety working group for the systematic review of the flow of materials through a process. It concentrates on key locations in the process known as study nodes and uses a series of guide words and parameters to examine possible deviations and the causes and consequences of deviations (Goidwaite 1985). 

The HAZOP study was originally developed for the chemical process industry. The analysis team applies a set of so-called guidewords (like OTHER THAN or MORE ) to each combination of a process step (for instance a vessel) with a parameter (e.g. temperature) and analyses possible deviations fi-om design or process intent expressed by the combinations with respect to causes, consequences, and existing detection as well as risk mitigation measures finally, further risk reduction measures are recommended if necessary. 

The HAZOP team focuses on specific portions of the process called nodes . A process parameter (e.g. flow) is identified and an intention is creat for the node under consideration. Then a series of guidewords is combined with the parameter flow to create a deviation. For example, the guideword no is combined with the parameter flow to give the deviation no flow . The team then focuses on listing all the credible causes of a no flow deviation beginning with the cause that can result in the worst possible consequences the team can think of at the time. Once the causes are recorded, the team lists the consequences, safeguards and any recommendations deemed appropriate. The process is repeated for the next deviation until completion of the node. The team moves on to the next node and repeats the process. 

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