(11c) Using Bowtie Metodology to Analyze the Piper ALPHA Disaster

Débora Brito dos Santos Risktec Solutions Ltd Debora.Brito@Risktec.tuv.com

Gustavo Correa YPF S.A. gustavo.correa@ypf.com

ABSTRACT

There were many major process safety incidents that marked recent history, Piper Alpha is one of them.

On the afternoon of July 6, 1988, a series of explosions occurred on the Piper Alpha platform in the North Sea.

A large fire spread to most of all modules on the top of the oil platform that ended up collapsing into the sea, killing a total number of 167 people and injuring many others.

This was the world's largest offshore oil disaster affecting 10% of UK oil production and causing financial losses of approximately £ 2bn (the equivalent of US $ 5bn these days).

It is important to ask ourselves:

• What went wrong with Piper Alpha?
• Why did it have such disastrous consequences?
• And what lessons can still be learned today?

Applying Bow Tie methodology to the Piper Alpha's incident, identifying threats and possible consequences, the corresponding preventive and mitigating barriers con be defined, including escalation factors.

The goal is to demonstrate how Bow Tie methodology could be used for the hazard identification and risk assessment for different scenarios at Piper Alpha Disaster, and subsequently identify those barriers that failed.

In the Piper Alpha disaster, simultaneous failures of both preventive barriers occurred and an important lesson to consider is the need to have effective control over the barriers, establishing responsible parties that allow us to ensure their permanent availability.

A major accident such as the one above normally occurs due to simultaneous failures in the management system barriers.

None of the large losses at Piper Alpha are the result of the failure of a single barrier. The scenario unfolded because many of the barriers did not fulfill their function, and during the proactive Bow Tie exercise the exact combination of events from the incidents could be shown.

This Bow Tie methodology enables the identification of potential weaknesses that may give rise to the holes in Reason's Swiss Cheese model and generates recommendations for measures to be taken to fill those gaps, strengthening, or adding barriers.