Autumn 2007 for

(Bestemmelse av SIL-nivi ved LoPA-analyse) Various approaches have been suggested to determine the appropriate safety integrity level (SL) for safety instrumented functions (SIFs). Some of these approaches are indicated in the international standards IEC 61508 and IEC 6l5l I and also in the application guide OLF 070 for the Norwegian oil and gas industry. The main objective of this master thesis is to study the applicability of the semi-quantitative approach Layer of protection analysis (LOPA). LOPA is briefly described and recommended in IEC 61511 and in guides from the Center for Chemical Process Safetv of the American Institute of Chemical Ensineers. As part of this thesis, the candidate shall: L ldentify, become familiar with- and give a brief description of available approaches for determination of appropriate Sll--levels, Pros and cons related to the various approaches shall briefly be highlighted. 2. Give a detailed presentation of the LOPA approach and illustrate its use through simple examples. 3. Carry out a case study on Petrojarl Varg and analyze this case by LOPA and selected alternative methods. Compare the results from the various methods and discuss possible deviations. 4. Identify and discuss practical advantages and disadvantages by using LOPA