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Group of Safety and Logistics of Maritime Transportation > 5.4 Maritime Safety and Human Factors > Publications
Sobral, J. and Guedes Soares, C. (2014), “Risk Management based on the Assessment of Safety Barriers”, Maintenance Performance Measurement and Management Conference 2014 (MPMM2014), Coimbra, Portugal, 4-5 September, pp. 205-212
In industry one of the main concerns is to keep risk under accep table limits. The purpose is to avoid the occurrence of undesirable events and reduce or mitigate their consequences. To achieve these goals one can act on prevention reducing the probability of occurrence of such events a= nd/or on protection reducing the severity of their effects. For the later = purpose Safety Barriers are usually applied. A Safety Barrier is a physical and/or non-physical mean planned to prevent= , control or mitigate undesirable events in the context of an accident sce= nario. These Safety Barriers are often classified according to their natur= e and inherent function as =E2=80=9Cphysical=E2=80=9D, =E2=80=9Ctechnical= =E2=80=9D and =E2=80=9Chuman=E2=80=9D barriers or in accordance with their functioning regime as =E2=80=9Cactive=E2=80=9D or =E2=80=9Cpassive=E2=80= =9D barriers. It is important to assure that Safety Barriers perform their function if n= eeded, being operational when demanded. This means that a careful analysis should be periodically done to evaluate or assess the expected performanc= e of the safety function by examining their effectiveness, response time o= r confidence level (reliability).
Once a low demand frequency of Safety Barriers due to a real necessity is expected, the assessment of their performance is often achieved by tests o= r inspections in order to determine the probability of failure on demand (=PFD) and the so-called hidden failures. Regarding the usual state of the m= ajority of these technical barriers, they are referred as E2=80=9Cdormant=systems=E2=80=9D. This paper deals with Safety Barriers describing their characteristics and presenting a methodology to assess technical Safety Barriers, sometimes also called Safety Instrumented Systems (SIS), based on test/inspection fre= quency, the correlated PFD and the corresponding Safety Integrity Level (S= IL). Thus, the impact of a specific Safety Barrier assessment on risk can be evaluated.
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