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HAZOP Terminology, Guide Words, Process Parameters & Deviations

The commonly used Hazop terminologies (left Table) and analysis guide words (right Table) are shown below:

Hazop terminologiesHAZOP Guide Words & Process Parameters

The guide words provided above represent a standard set. Most companies customize their sets of guide words and many companies use different sets based on the type of unit operation being examined. The guide words AS WELL AS, PART OF, and OTHER THAN can sometimes be conceptually difficult to apply.

AS WELL AS means that something else happens in addition to the intended design intention. This could be boiling of a liquid, transfer of some additional component, or the transfer of some fluid somewhere else than expected.

PART OF means that one of the components is missing or the stream is being preferentially pumped to only part of the process.

OTHER THAN applies to situations in which a material is substituted for the expected material, is transferred elsewhere, or the material solidifies and cannot be transported. The guide words SOONER THAN, LATER THAN, and WHERE ELSE are applicable to batch processing.

Examples of process parameters include the following:

Each guide word is combined with relevant process parameters and applied at each point (study node, process section, or operating step) in the process that is being examined. The following Table showed examples of creating deviation using guide words and process parameters:

Click here for more discussion on forming meaningful deviation from guide words. Some examples of various deviations and their causes are also available. Click here for more information.


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