Risk grade evaluation of gas pipelines based on matter-element and extension set theories

To perform risk evaluation and risk grade division on gas pipelines for risk management is a scientific management method to ensure safety operation and to boost the benefit of pipeline companies. Various factors which affect pipeline failure probability and probable results caused by gas pipeline failure should be taken into consideration in risk grade division. Based on preliminary definition of urban gas pipeline risk grade, relevant theories about matter-element and extension set are introduced to analyze constitutive factors for gas pipeline risk. Some tool functions, e.g., correlation function, are used to define and calculate the risk grade of gas pipeline; calculation functions and procedures are identified. The main calculation methods for risk grade division are introduced according to its calculation process. Corresponding measures are put forward for risk grade evaluation of urban gas pipeline.