A review of layer of protection analysis techniques for oil and gas industry

Abstract

The paper indicates advantages (and disadvantages) of layer of protection analysis (LOPA) over other methods to support its paramount position among different process safety analysis (PSA) methods in use today. Its simplicity (using order-of-magnitude estimates for all elements that constitute an accident scenario), universality (easy adaptation to particular needs), directness to indicate the effect of risk reduction measures as well as to assess the total level of risk to be compared with the company risk tolerance criteria are strong arguments for wider application of LOPA. However, the method may have some limitations (disadvantages) in comparison to other methods and therefore different extended approaches of LOPA have been developed to overcome the problem. Those approaches include an inclusion of an expert system into accident scenario identification (ExSysLOPA), new approach to deal with uncertainty connected with input data (fuzzy LOPA) as well as for explosion at workplace risk assessment (ExLOPA). Some of these combined techniques will be presented here and they support and extend the applications of layer of protection analysis, especially for safety assurance assessment of risk-based determination that is used in oil and gas process industries.