REVIEW APPLICATIONS FOR TYPICAL FACILITIES

The bulk of process hazard analyses (PHA) in the petroleum and related industries will be either a HAZOP or a What-If review. Generally in the upstream sector, 60 - 80% of the safety reviews will be a What-If review, while in the downstream sector, 60 - 80% will be HAZOP reviews. 

Both HAZOP or What-If reviews are generally organized and conducted in a similar fashion. The HAZOP review is more detailed and structured, while the What-If approach is typically broader and free flowing. 

It has been found that the What-If style of process hazard analysis is a convenient method to use for a simple facility. For simple facilities, the detailed HAZOP approach has been found to be tedious and just as productive as a What-If method. The What-If approach stimulates generation of new ideas and discussion to cover issues associated with the items under review, as well as addressing generic issues. The specific HAZOP review is not necessary when the process is simple and well understood by the reviewing team. The team can readily review the major items of concern by asking What-If questions such as what happens when a pump fails, without relying on itemized and detailed variations of a process condition by the HAZOP method, such as high level, low pressure, etc. 

Processes that contain unusual, complicated or extremely hazardous materials should be reviewed by the detailed HAZOP method to ensure major possible events have been accounted for which may not be familiar to the team. This may also be true when a high employee or public population may be exposed to potential hazards (such as may be the case with some offshore oil production facilities). 

In the concept stages of a project, when details of the design are not known, emphasis should be put on the several accidental scenarios with a potential of impacting the main safety functions. 

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