某核电厂高压加热器系统疏水器在服役过程中发生局部减薄,采用宏观观察、化学成分分析、金相检验、扫描电镜分析及X射线衍射等方法对疏水器壁厚减薄原因进行了分析,并对疏水器流道的流态进行了模拟计算。结果表明:高流速介质的冲刷减薄及流体加速腐蚀减薄是造成疏水器减薄穿孔失效的直接原因;阀体内表面脱碳导致材料的硬度降低、抗冲刷能力和耐腐蚀性减弱,从而加速了阀体的壁厚减薄。

The local thinning of the high-pressure heater system of a nuclear power plant occurred during the service process. The reasons for the thinning of the wall thickness of the trap were analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscope analysis and X-ray diffraction, and the flow pattern of the trap channel was simulated. The results show that the erosion thinning of high velocity medium and the fluid accelerated corrosion thinning were the direct causes of the thinning perforation failure of the trap. The decarburization of the inner surface of the valve body led to the decrease of the hardness, erosion resistance and corrosion resistance of the material, which accelerated the wall thickness reduction of the valve body.