Research On Optimal Design Technique For The Anti-Corrosion System Of Ocean Engineering

Sufficient reliability and safety of ocean engineering structure have been demanded as the development of offshore oil and gas resources. Corrosion is one of the major causes of structural failure. Compound anti-corrosive techniques, including coating system and sacrificial anode cathodic protection system, have been widely employed as the anti-corrosion measurement in ocean engineering. The design technique for the anti-corrosion system in domestic engineering practice is old fashioned, which is mostly based on experience and code, leading to the incapacity of fine expression toward the evolving state of anti-corrosion system during the entire life-cycle. Therefore, it is of great importance to research on efficient means of optimal design technique for the anti-corrosion system of ocean engineering.With regard to optimal design technique for coating system and cathodic protection system, the major research works and results in this thesis are concludes as follows:(1) Study on optimal design technique for coating system. A data bank, which includes coating solutions, coating types and coating brands in most engineering cases, has been formed via the survey of academic literature, engineering practice and coating supplier. The optimal design database for coating system has been established by means of optimization and parametric processing of the initial data. By applying Expert System method, Optimal Design Software of Coating System aiming to realize the function of detailed design and optimal design has been developed.(2) Study on key techniques in optimal design of cathodic protection system. Research and development have been realized in this thesis concerning certain key techniques including parallel computing,3D visualization, and communication&transmission amid internal and external networks, by which supporting the research work in optimal design of cathodic protection system.(3) Study on optimal design technique for cathodic protection system on external surface of submarine pipelines. An optimal design technique using numerical simulation has been carried out. Large-scale samples which can fully describe the vast majority of anti-corrosion systems’state on external surface of submarine pipelines in engineering practice have been put forward. Large-scale numerical simulation has been realized using Boundary Element Method (BEM) and thus provides the database for optimal design. Based on the correlation analysis between in-out parameters, two-stage Artificial Neural Network (ANN) has been trained using Levenberg-Marquardt (L-M) algorithm and Bayesian Regularization Algorithm.(4) Study on optimal design technique for cathodic protection system of underwater structure of ocean platform. On the basis of traditional code design system, optimal model has been put forward using simulating calculation and analysis based on BEM for specific structure. Optimal variables are defined as variance of protective potential and mean protective current density. As for the underwater structure of those ocean platforms with a certain type, parametric technology has been studied to provide complete definition of structural surface. Afterwards, the research approach of optimal design has been raised. The availability of the methods above has been verified by case study of jacket platform.(5) Development of Optimal Design Software of Cathodic Protection System. Research achievements related to optimal design technique for cathodic protection system in this thesis have been crystalized and integrated as Optimal Design Software, possessing high application value in engineering practice.