锅炉集箱孔桥裂纹的检验与分析

Inspection and Analysis of Cracks in the Boiler Header

本文通过对电站锅炉的内部检验,采用超声检测方法发现高温过热器出口集箱孔桥部位存在超标缺陷,经射线探伤验证,孔桥处发现多道裂纹。对集箱更换后进行了解剖,实际状况与探伤结果一致,经过对集箱蠕胀测量、金相检验、机械性能试验等,对裂纹产生的原因进行了认真分析,认为集箱过热器管孔周围发射状裂纹属于蠕变裂纹,高温和局部应力集中是造成管孔周围蠕变裂纹的主要原因,并从设计、制造、检验、使用等环节提出了预防措施。

During the internal inspection for the power plant boiler, excessive defects were found in the high temperature superheater outlet header ligament by ultrasonic testing, where many cracks were detected by radiographic inspection. After the dissection of the header, the actual situation was the same as and the detection result. The cause of the crack was carefully analyzed combining creep expension measurement, metallographic examination and mechanical performance test. It was considered that surrounding cracks around the pipe hole of superheater header were creep crack, and the high temperature and local stress concentration were the main reasons. Preventive measures were put forward in the aspects of design, manufacture, inspection and use.