The Risk-based Inspection And Repair Schedule For The Long-distance Pipeline Subject To Corrosion Defects

The risk based inspection planning can establish optimized inspection and repair plans for meeting the risk acceptance criterion of a component. Since a relatively large percentage of risk is associated with a small percentage of components, the risk based inspection planning shifting inspection resource to high-risk components. In addition, the risk based inspection planning is a condition of the component and for prioritizing inspection efforts in accordance with the importance of the components and the deterioration mechanisms.The currently existing methods of inspection and maintenance were given and analysis the principle of every method. The advantages and disadvantages of every method t were proposed. The pipeline was divided into different parts based on the result of the risk-based inspection. Different part was adopted different inspection and maintenance schedule. The corrosion defects were divided into three classes according to the degree of corrosion, different class was repaired by different methods. The inspection interval and the times of inspection were calculated as well as the method of the inspection and maintenance cost was given under the different way. It is a theoretical basis to choose the inspection interval, inspection method and maintenance method.There are many uncertainties in the process of inspection such as apparatus and equipments, work environment, human factors and so on. If we ignored these uncertainties, the wrong decision would be made, and then the cost would be more, so it is necessary to consider these uncertainties into the schedule of inspection and maintenance. The imperfect inspection was analyzed in this paper, the inspection intervals, the times of inspection and the quantity of the defects were calculated considering the imperfect inspection. The schedule of inspection and maintenance was proposed for long-distance pipeline subject to corrosion defects under imperfect inspection.Finally, the summary of this paper was given, some key problems and future development directions are pointed out for the research of risk based inspection and maintenance planning for long-distance pipeline from now on.