Risk Assessment Of Marine System Related Dynamic Positioning Of Semi-Submersible Vessel

The marine system is an important part of the semi-submersible dynamic positioning system(DP)and a key guarantee part for the safe and reliable operation of the DP system.Whether the DP-related marine system is safe and reliable is one of the important functional guarantees features of the semi ship,and it has become the most important factors for the safety and reliability of the DP system.At present,the design of the associated marine system for the semi ship DP system and its risk analysis and risk management are receiving more and more attention from all parties.The risk impact analysis method is also constantly being updated with the development of the industry.In the current design and manufacture of semi vessels and future engineering operations,operators are generally more likely to get conclusions and quantified results on the expected “risk status”in order to optimize the design and guide the later work.Based on the relevant domestic and foreign related literature and professional technical consultation report,combined with the actual project,the FMEA method is used to carry out risk analysis of the DP associated marine system of the project,and the project design is targeted.And some constructive suggestions were made in the later work.Regarding this paper,we studied the development of the ship dynamic positioning system(DP)and the development history of the failure mode impact analysis method,summarized the principle,specific methods and implementation steps of the fault analysis,collected and summarized the risk of applying the fault analysis method to the DP system of semi ship.On this basis,the detailed research on the associated turbine system and equipment configuration of the company’s semi-submersible ship dynamic positioning system was carried out,and the FMEA analysis based on the risk ordinal method was carried out.Firstly established the FMEA table and data definition for the target semi-submersible project,and then defined the "fault occurrence frequency”,"fault severity" and "fault detection degree" parameters for each item.The point failure mode was used to score statistics,and the RPN value of each failure mode was calculated.At the same time,to describe the causal relations between various fault modules,and make them clearer,this paper studied the fault tree-based FMEA method,including the determination of specific top events and boundary conditions,tree building rules,and fault tree minimum cutting.Taking the 3 type thruster faults as an example,sequencing them by the basic cut and the minimum cut set analysis method,and the risk order of each fault mode was sorted.A Bayesian network-based probability analysis was also carried out on the fault tree of the main thruster system.By quantitatively analyzing the research data of the FMEA of the semi-submersible ship’s dynamic positioning system associated with each turbine system,we proposed professional suggestions for its designation and operations,which further improves the ship’s safety and reliability.