Functional Barrier Model - A Structured Approach To Barrier Analysis

Abstract Barrier Analysis has become a key element in managing major hazards and process safety, including and increasing attention from regulators for barriers and barrier management. In practice however the quality of the barrier analysis is often very poor and differences in understanding of barriers prevails throughout due to the lack of a good, generally accepted, barrier model and the absence of a good process for defining barriers. Typically focus has been on the equipment part of barriers (Safety Critical Elements - SCE's). The objective of this paper is to describe a structured approach for barrier analysis based on a Functional Barrier Model to determine independent and fully functional Barriers and their barrier elements. The method as described has evolved from best practices and projects for regulators, operators and drilling contractors and provides the latest views on barriers and barrier management. The approach focuses on the Barrier Function; why do we have this Barrier? Based on this Barrier Function an in-depth analysis of barriers is described in 4 consecutive steps; 1 Establishing Barrier Type; How the Barrier delivers its function (passive, active or procedural). 2 Identifying Primary Barrier Elements; What components are required for delivering the barrier function based on the " Sense-Decide-Act" model for a barrier to be fully functional. 3 Identifying secondary barrier elements, all measures in place to ensure that a specific barrier functions as intended and is effective. 4 Assign ownership to barriers and barrier elements. With the use of the Functional Barrier Model it is demonstrated that the procedural part of barriers (Safety Critical Tasks) can be equally or even more important. Especially in a drilling environment, where there is a low level of automation and a high dependence on the human element, most of the barriers are a combination of equipment and human interaction instead of what is currently perceived as "hardware" barriers. Application of the Functional Barrier Model results in fewer but real barriers in which safety critical elements and safety critical tasks are included in a balanced manner. As the use of Barriers increases the maturity of our thinking and understanding of barriers needs to increase as well. The Functional Barrier Model provides this necessary maturity and increased understanding of Barriers and forms the sound foundation that is required for good Barrier Management.