# Risk Identification of FPSO Oil and Gas Processing System Based on an Improved FMEA Approach
###### Abstract  
It is increasingly necessary to perform risk analysis in marine structures, to ensure system safety, as they are large and complex. In view of the shortcomings of failure mode and effect analysis (FMEA), a modified fuzzy TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) approach is proposed that is based on fuzzy evidence reasoning (FER), and considers the risk factor rating and relative weight. The presented method is used to prioritize the risk of equipment failure modes for the floating production storage and offloading system (FPSO) oil and gas processing system. The subjective weights and objective weights of occurrence (O), severity (S), and detectability (D) have been considered comprehensively. The subjective experience of the experts and the objective information reflected by the O, S, and D ratings are all included in the weights, making the ranking results closer to reality. The results can be scientific references for decision-makers in risk identification. FPSO oil and gas processing system; failure mode and effect analysis (FMEA); fuzzy evidence reasoning (FER); fuzzy TOPSIS; comprehensive weighting method +
Footnote †: journal: Medical  
of O, S, and D. In fact, 120 different RPN values can be calculated from O, S, and D, and many of the numbers are in the range of 1-1000. The RPN elements have many duplicate numbers as well. Hence, the mathematical formula for calculating RPN is questionable and debatable. (5) RPN uses only three risk factors to evaluate safety, but the other important risk factors, such as the economic direction of the error, are not considered. The AIAG/VDA (Automotive Industry Action Group/Verband der Automobilindustrie) FMEA Handbook [13] recommends using action priority (AP) fields in place of the RPN in design failure mode and effects analysis (DFMEA), potential failure mode and effects analysis (PFMEA), and FMEA for monitoring and system response (FMEA-MSR) to evaluate priority for actions. The AP also provides all 1000 possible combinations of S, O, and D; and the AP table recommends that measures be classified into high priority (H), medium priority (M), and low priority (L). In essence, AP has the same disadvantages and problems as the traditional RPN. In order to overcome one or more of the limitations and to improve the effectiveness of the traditional FMEA methods, several scholars have carried out the risk ranking of failure modes by combining fuzzy evidence theory, Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) theory, grey correlation theory, Decision-Making Trial and Evaluation Laboratory (DEMATEL) theory, and other methods. [PERSON] et al. [14] proposed the DEMATEL method to be applied in FMEA risk priority sequencing. [PERSON] et al. [15] developed the FMEA method based on the evidential reasoning method to simulate the diversity and uncertainty of rating in the process of FMEA analysis. [PERSON] et al. [16] proposed the TOPSIS method to rank the risk priority of all failure modes. [PERSON] and [PERSON] [17] presented a risk analysis method based on fuzzy evidence reasoning aiming at the uncertainty of risk rating and the question of FMEA. Considering the correlation between failure modes, [PERSON] et al. [18] introduced fuzzy set theory and decision test, and an experimental evaluation method into FMEA, and combined it with TOPSIS theory to analyze the failure modes of offshore wind turbine, to improve the credibility of the results. The information safety of small cities was evaluated by [PERSON] et al. [19] based on trapezoidal fuzzy numbers and grey correlation theory. Based on cloud model theory and hierarchical technology, [PERSON] et al. [20] converted the linguistic evaluation of failure modes into cloud fuzzy numbers, combining the advantages of cloud model in dealing with the fuzziness and randomness of linguistic evaluation, and the advantages of hierarchical TOPSIS solving complex decision-making problems.