A novel approach in risk evaluation for ship-to-ship (STS) transfer of cargo using process failure mode and effects analysis (PFMEA)

The ship-to-ship transfer (STS) of oil and oil products plays currently an important role on a worldwide scale. Usually, it refers to the transfer of cargo between seagoing ships positioned alongside each other. Although the procedure of STS transfer has become a day-to-day practice, it remains a difficult operation, which deserves special consideration. To reduce the adverse effect of a potential accident on humans as well as on the environment, a risk assessment is necessary to be done to evaluate the hazards that derive from such a difficult procedure. To this end, the process failure mode and effect analysis (PFMEA), which is under the umbrella of the traditional failure mode and effect analysis, is properly modified and applied to assess the hazards of a typical STS transfer procedure. PFMEA is based on the risk priority number with regard to each risk related to the procedure of interest by multiplying the numerical values of the severity, occurrence and detection indices. Although PFMEA is currently applied mainly to manufacturing processes, the aim of the paper was to implement this methodology to STS transfer of petroleum products. According to the study of PFMEA implementation, the petroleum cargo is the product similar to the product in a manufacturing procedure; hence, the different phases of the STS procedure are similar to the production line of the manufactured product. Moreover, proposals to eliminate the disadvantages of the implementation of PFMEA by a qualitative manner (using linguistic terms) are proposed. The objective target of this effort is to assess and evaluate the effectiveness of implementing the PFMEA in a maritime activity and therefore to address the advantages and disadvantages of such an approach.