某大型火力发电厂末级再热器G102钢管发生泄漏,采用宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析、力学性能测试等方法分析了泄漏原因。结果表明:末级再热器G102钢管段运行了16万小时,组织老化、性能严重劣化;G102钢管管段内、外壁氧化皮影响了热交换,使金属壁温升高,加速了材料组织老化、性能劣化,最终使G102钢管达到蠕变寿命后期,并发生泄漏;设计及结构因素也加速了材料组织老化和性能劣化。最后对末级再热器G102钢管的安全稳定运行提出了相关建议。

Leakage occurred to the G102 steel pipe of the final reheater in a large thermal power plant. The causes of leakage were analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscopy and energy spectrum analysis, and mechanical property test. The results show that the G102 steel pipe section of the final reheater had been running for 160,000 hours, and the structure was aging and the performance was seriously degraded. The oxide skin of the inner and outer walls of the G102 steel pipe section affected the heat exchange, increased the temperature of the metal wall, accelerated the aging of the material structure and the deterioration of the performance, and finally made the G102 steel pipe reach the later stage of creep life and leak. The design and structural factors also accelerated the aging and performance degradation of the material. Finally, some suggestions were put forward for the safe and stable operation of the G102 steel pipe of the final reheater.