Risk Assessment Method For Subsea Pipeline Based On Uncertain Bow-tie Model

Bow-tie model is one of the main research contents in the field of risk assessment,mainly used to analyze the risk situation of industrial production and other scenarios.The Bow-tie model can intuitively show the internal relationship between potential hazard sources and consequence events.Therefore,it is of great significance to use the Bow-tie model for risk assessment of submarine pipelines.The traditional Bow-tie models are modeled and analyzed based on probability theory,and there are three important conditions for using probability theory to deal with problems: events need to be clearly defined;There are lots of samples;There is probabilistic repeatability between samples.However,due to the complexity of Marine environment,the amount of available submarine pipeline data is small,which does not meet the requirements of probability theory modeling.Therefore,it is not suitable to use probability theory to model and analyze Bow-tie model.Experts are often required to assess basic events based on their own experience.Therefore,the uncertain Bow-tie model is proposed in this paper,and the risk assessment of submarine pipeline is carried out on this basis.The main research contents of this paper are as follows:(1)Proposed the risk assessment method of submarine pipeline based on the uncertain Bow-tie model.The corrosion failure index system is determined according to the Marine environment of a pipeline.After the index system was established,corrosion failure accident tree analysis and corrosion failure event tree analysis were carried out respectively to complete the qualitative analysis of the uncertain Bow-tie model.On completion of qualitative analysis,based on uncertain rules Bow-tie model to calculate the reliability and risk grade of submarine pipeline corrosion failure reliability,blamed for the deaths of submarine pipeline corrosion failure to identify the hazards of the basic event,through quantitative analysis,through the results of a pipeline risk analysis concluded that the rationality and the comparative analysis with the actual use of the pipeline.Finally,according to the concept of certainty importance degree,the certainty importance degree of pipeline failure event and risk level are analyzed respectively.(2)Proposed time-varying submarine pipeline corrosion risk prediction method based on uncertain Bow-tie model.During the operation of submarine pipelines,the failure time of basic events in the uncertain Bow-tie model and the execution time of control events obey the uncertain distribution.Under this condition,the corrosion failure and risk status of submarine pipelines are predictive analyzed.The distribution function of pipeline corrosion failure and risk grade is obtained,which can provide basis for experts to make planned scientific decision.