(21c) Understanding Major Process Incidents through the Swiss Cheese Model

Swiss cheese model is one of the commonly used tool to demonstrate how the identified hazards are managed by adequate preventative and mitigation protection layers and the associated management programs to maintain their integrity and availability.

The size of the holes in the Swiss Cheese corresponds to the level of weaknesses in the management systems. The incident occurs when the multiple safeguard’s holes line up.

Piling of multiple safeguards is not the solution. Maintaining the integrity of fewer safeguards is the right way. The priority should be to eliminate rather than to prevent the lineup.

There are numerous causes and opportunities to identify and fix these holes proactively. Each cause gives multiple signals which are either ignored or not recognized or not addressed.

In this paper author explains the following with examples.

1. Why and how the holes in a Swiss Cheese Model lineup – most common causes?
2. Why do we fail to recognize until an incident occurs?
3. What are the best practices and proactive approaches to recognize the weaknesses in the management systems before the holes lineup and incident hits?
4. How applying hierarchy of controls is the best option?

The author in his current role as a senior risk control engineer performs audits and inspections of a variety of high hazard industries including refineries, chemicals, petrochemicals, oil terminals, etc. In this paper, he will share real life scenarios and examples from variety of high hazards operating facilities including challenges and best practices.

The paper will be concluded by sharing the strategies on how to recognize the management system gaps and apply best practices to maintain the integrity of safety critical equipment to prevent process incidents.

Keywords: safeguard’s integrity, Swiss Cheese, management system causes, risk management