| This paper was supported by China Special Equipment Inspection and Research Institute, and it originates from the 08 subject'The Research of Risk Based Inspection and Comprehensive Safety Evaluation Technology on the Group of Large Atmospheric Storage Tank'which belongs to'Eleventh Five-Year'National Science and Technology Support Program project'The Key Research and Demonstration Projects of Lifeline Security'(ID: 2006BAK02B01-08). The research put emphases on quantitative risk assessment techniques and the actual application of the technique, put forward the practical and feasible risk evaluation method for atmospheric storage tank.The storage tanks are widely used in petroleum, chemical industry, national defense, transportation and many other fields. It's a sort of high risk special production and storage facilities. The management of storage tanks in China is performed on the base of periodic or sample inspection which will result in cost waste and hidden danger. The risk based inspection (RBI) is a sort of idea and method which pursue the unification of security and economy. It can identify the risk distribution of a group of the storage tanks effectively, turn preventive inspection to forecasting inspection and achieve the storage tank's scientific evaluation and effective management.In this paper, the theoretical method of storage tank RBI technology has been studied from failure probability and failure consequence and the quantitative risk analysis model of storage tank has been established. In failure possibility analysis, combined with the corrosion mechanism of storage tank, the main factors which influence the corrosion rate of the tank's floor and wall have been determined from the product side and the soil side (air side) respectively and the corrosion rate computing method has been brought forward. In failure consequence analysis, failure consequence level was determined by complex weighted computing with consider of the possible failure modes and failure consequences of storage tank.In this paper, the project application research of storage tank RBI technology has been carried out for the first time in China. The application object included 525 atmospheric storage tanks, 1050 equipments. In this application research, the risk level of various equipments and the risk distribution of the storage tanks were determined. The targeted inspection strategy was put forward according to the results of risk evaluation, and the risk was reduced effectively by the risk evaluation. The results of risk analysis indicate:â‘ the risk distribution of a group storage tanks conforms to the principle that the majority of risk concentrate in small partial storage tanks;â‘¡there is no high risk level equipment from the result showing that the storage tanks don't have the high risk in general as a atmospheric pressure device;â‘¢the level of medium-high risk equipments is mainly resulted in the high failure possibility level;â‘£the bottom floor of storage tank take on higher risk level and the wall of storage tank take on lower risk level. In addition, this paper brought forward the general application procedures of storage tank RBI technology by summing up the problems and experiences. The procedures include: the principles and content of data collection, risk analysis process, the principles and methods of inspection strategy establishment.In order to verify the effect of storage tank RBI technology application, this paper selected 3 storage tanks (1 medium-high risk level and 2 medium risk level) to carry out Acoustic Emission inspection and 2 storage tanks (1 medium-high risk level and 1 medium risk level) to carry out Magnetic Flux Leakage inspection according to the result of risk analysis and the enterprise production requirements. The results of inspection demonstrate the storage tank RBI technology is a scientific and practical risk evaluation method. The evaluation results computed by AST RBI software are high reliable. In addition, the storage tank 108's risk level was not high, but it got localized corrosion perforation. This situation indicated that risk analysis can not include every detail and accidental factors. Therefore, the management of storage tanks can not only rely on RBI evaluation results, but also should pay attention to routine monitoring and maintenance and do the best we can to prevent the occurrence of accidental factors in order to achieve risk reduction and security. |
