The Stress Analysis And Safety Assessment Of Pressure Vessels With Flaws In Power Plant

Along with the rapid development of modern industry, the pressure vessels develop to the large-scale, complex, high parameter and the strict operating mode direction. The security of the pressure vessels arouses people's interest, and the safety assessment of the pressure vessels becomes more and more important. On the other hand, through safely evaluates may avoid some unnecessary repairs and discards, and may save the massive funds, manpower and physical resource. Developing the security assessment work to the pressure vessels of the power plant, not only may safeguard the safe operation of power plant ,the stably supplies power to the entire electrical network and raises the economic efficiency also has the important contribution.At present, the safety assessment of pressure vessels based on" Fitness for service" principle widely develops in home and abroad, and many new theories are developed. Accordingly, many new standards are established, such as BS7910, SINTAP, and GB/T19624 - 2004 and so on. The foundation of"Fitness for service" principle is the scientific method based on the theory analysis and the experiment tests. It substituted for"perfect was complete"method based on the experience, and can objectively guarantee the pressure vessel did not have any known mechanism expiration accident.This research is based on the project investigation and repeated discussion. The British standard BS7910 was the basic theory, and accordingly carried out the experiment, the computation of the stress parameter and an expert system was developed. In this research, the test materials were gathered from project location, and uniaxial tension test, fracture toughness test and impact-toughness test of the welding joint are made. Then a material parameter database was established; in the research process, the FEA models of typical power plant pressure vessels were established and the stress parameters were gained through simulation method, and a classified stress database was established. The material parameter database and the classified stress database is the important constituent of the expert system, which can enhance the efficiency and the accuracy of procedure of the flaw assessment. The expert system is an effective assistance method for the safety assessment of the flaws, and it may help the ordinary engineers and technicians to grasp the complex assessment process.