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12Cr1MoV life of the main steam pipe


State changes,[link widoczny dla zalogowanych], precipitation phenomena occur repeatedly, gradually reduce the creep resistance of metals, the creep activation energy is lower. The results obtained fully proved that the microstructure properties of the metal tube changes are interrelated to each other, while the macro-performance indicators of the metal reflects the results of its internal state changes. 2.2 The projected service life of power plant main steam pipe steam pipe design guidelines for the use of controlled stress, that steel in the design of temperature is divided by l0 million h rupture strength safety factor of 1.5,[link widoczny dla zalogowanych], as the design stress allowable value (basic allowable stress). Main steam pipe in the working state, the internal vapor pressure generated by discount stress zs, shall not exceed the basic allowable stress of steel. Usually l02 / h design life is the life of the tubes can be safe and reliable operation. For decades, the 12CrlMoV main steam line (540 ~ C, 9.8MPa) and life experience running a large number of studies have shown that less than the basic allowable working under stress conditions, the main steam pipe in service l0 million h, the safe use of there is a margin time. The duration and strength of steel and other metals lasting performance indicators. To determine the service life of steam pipes emperor, can be calculated with reference to thermal power plant steam piping stress technical requirements \Persistent strength formula derived minimum breaking time, steel strength reserve coefficient, creep parameters, pipeline Creep rate measured projected remaining useful life of other methods. Field measured by pipeline remaining life of the creep rate calculated as follows: pipe measuring point with the creep ll group, conducted since 1970 8 measurements, resulting in most of the creep rate of 0.1 ~ 0.3 × 10mm/mm ・ h. Pre-pipeline operation had reached the maximum creep rate 0.45 × 101ram/ram ・ h. In total 22 million h run, the total cumulative amount of 0.74% creep. Because the pipe to pipe diameter design uses 1% of the relative amount of creep life of the security of pipelines, the pipe service life of the period, allowing the remaining 0.26% creep about. Then run the main steam pipe, if the average remains 0.3 × 101mm/mm ・ h steady-state creep rate, remaining life can be lent to more than 80,000 hours. 3 Conclusion Jianbi Power Plant Unit 4 l2CrlMoV main steam pipe running 220,000 h, cutting pipe test results show that the use of performance indicators of metal pipe down, and gradually entered the aging state. But there was no significant creep damage, the metal in the late stage of the process of life. Analyzed and summarized the remaining useful life according to different calculation method results to determine the safety of the main steam pipe can continue to run from 7 to 80 000 h. (Received date :2002-07-15) (Continued from page 23) regions, key positions, key lines,[link widoczny dla zalogowanych], must be based on the actual level of contamination, to take transfer to climb, the replacement for the synthetic insulators such as measures to improve the level of dirt flash. (3) establish a system to improve the distribution of contamination in the survey area, approved, and adjustments. Contamination zone map is based anti-fouling work for the construction, expansion of the external insulation design of power transmission project and the transformation of operating equipment to provide the scientific basis for external insulation, but also the basis for operation and maintenance of power production. To this end, filthy area map must be accurate and complete. According to the growing phenomenon of dirty air, dirty district level over time will change, for the protection of the exact distribution of contamination areas must establish a system for regular distribution of contamination in the survey area, approved and adjustment,[link widoczny dla zalogowanych], it is recommended every 3 5 years once. Closely monitor the distribution of salt to achieve a reasonable, adhere to the monitoring of staff specialization. One by one (4) transmission and distribution equipment to adhere to the principles of Chapter cleaning. Ll0 ~ 500kV line on the external insulation configuration, lack of margin, according to the operating procedures required, must be regularly cleaned vase. To protect the effectiveness of cleaning,[link widoczny dla zalogowanych], cleaning should be scheduled before the season flashover. Key areas of contamination, according to inspection and testing, increasing the cleaning frequency. Substation for large and small repair, pre-testing and other work, the cleaning of porcelain repair as a pilot project to be. No cleaning or cleaning porcelain is not complete, operating personnel should refuse acceptance. Before the rainy season, should do the job impermeable leak-proof high-pressure chamber. (5) to strengthen the maintenance of insulator strings, testing and monitoring to prevent the insulator string of accidents burst out. Post flashover 500kV double track does not trip, confirmed the composite insulator has a good anti-fouling properties, should promote the use of grade Ⅲ dirty areas. (Received: 2Oo2 a O8-2o) 1
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