INCIDENT

Buncefield Layers of Protection

In a facility that generally runs with a high degree of stability, layers of protection that don’t get used can form holes, both figuratively and literally.

Examining the Buncefield fire in 2005 could be a textbook example of layers of protection and the “Swiss Cheese Effect.” It’s the illustration that if you take slices of Swiss cheese and lay them on top of each other, if there is a hole in the same position on every slice, now matter how many you stack up, that hole will go all the way through.  Buncefield had traditional layers of protection as part of its safety management system:

• Basic process control system (BPCS)
• Alarms
• Safety instrumented system (SIS)
• Physical containment

Each of these was a single point of failure with no redundancy. Each failed in its own way with disastrous results, so let’s look at them one by one.

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