Defining process safety should be quite straightforward. However, what people mean with this term can vary quite a lot, and what to include in the term depends a lot on the understanding people have of the anatomy of severe accidents. Personally, I have met the following different understandings of the topic:

• Process safety is what is governed by API 521 (basically steel strength and dimensioning of pressure relief valves)
• Process safety is the technical measures taken to stop an accident from occurring
• Process safety is the sum of organizational and technical systems involved in mitigating risk of major accidents

The first statement is obviously too narrow – especially as we know that more than half of accidents are down to human factors! Definition number 2 is a traditional view, and slightly more mature as it includes both the safety instrumented system and alarm management (to a certain extent). The last definition is maybe the most “modern”, and includes organizational culture, safety leadership as well as the technologies included in the first and second definitions.

A complete understanding of barrier systems, which is really what risk management is about, requires an understanding of which factors are influencing accident risk, and what can be done to mitigate the risk. This requires that the asset owner thinks not only about “proof testing”, “compliance” or “asset management”, but also about:

• Leadership
• Barrier integrity
• Maintenance
• Monitoring
• Design
• Competence management
• Permit to work system
• Dynamics of plant and controls in normal and degraded modes
• Etc, etc, etc.

In other words – to keep risk under control you need to take the full complexity of your operations into account. A purely technical view on process safety is thus simply not good enough.