Study On Comprehensive Assessment Method And Model For External Corrosion Of Crude Oil Storage Tank Floor

With the development of the energy and chemical industry,as well as the promotion of China’s strategic plan for oil reserves,the use of large crude oil storage tanks is increasing year by year.The leakage of crude oil storage tanks due to corrosion is drawing more and more attention,and leakage of storage tanks may cause serious casualties,economic losses,and environmental pollution.The outer floor is one of the most severely corroded parts of the crude oil tank,and there are many complicated and interactive factors affecting the corrosion.The complexity of the corrosive environment and the special nature of the equipment increases the difficulty of the external corrosion of tank floor detection and assessment.To this end,this paper uses the analytic network process and intuitionistic fuzzy set theory and method to build a set of multi-indicator integrated assessment model and will be successfully applied to the assessment of external corrosion of tank floor,providing reference for corrosion protection,in-service operation and service life extension of tank.The main research contents and results are as follows:(1)First of all,the corrosive environment and mechanism of the external corrosion of tank floor are summarized and analyzed.Soil corrosion and stray current interference directly affect the bottom plate outside the corrosion,cathodic protection and coating protection in the tank in service process due to poor results,protection failure,and other issues indirectly determine the corrosion state.There are complex interactions among the factors that determine soil corrosion,stray current interference,cathodic protection and coating protection.(2)Combining triangular intuitionistic fuzzy number,analytic network process,and intuitionistic fuzzy comprehensive evaluation,this paper proposes a comprehensive assessment method based on triangular intuitionistic fuzzy analytic network process and triangular intuitionistic fuzzy comprehensive evaluation.The dependency and interaction among the influencing factors are dealt with by the triangular intuitionistic fuzzy analytic network process;the influence of each factor on the assessment results is considered comprehensively by the triangular intuitionistic fuzzy comprehensive evaluation;the uncertainty in the assessment is solved by the triangular intuitionistic fuzzy numbers,which makes the assessment results more scientific and accurate.(3)This paper establishes a multi-level,multi-indicator system of external corrosion of tank floor,from the soil corrosion,cathodic protection,coating protection,stray current interference of the four sets of influencing factors,including soil resistivity,cathodic protection effect,DC interference,coating stripping,and other 13 influencing factors.Establishes the factors corresponding to different levels of corrosion membership and nonmembership function.According to the method proposed in this paper,a comprehensive assessment model of external corrosion of tank floor was constructed,and the application study was carried out by example to prove the engineering value of the model.(4)Developed a comprehensive corrosion assessment system software for the external corrosion of tank floor,including computer application software and smartphone application software.The purpose is to provide valuable information for tank operation,corrosion protection,and maintenance,to reduce the ecological,economic and safety risks caused by the corrosion and leakage of the tank outer floor.