600MW超临界锅炉水冷壁管爆管原因分析

Analysis of Water Wall Tube Explosion in 600MW Supercritical Boiler

某600MW超临界锅炉水冷壁管(15CrMoG)发生爆管失效事故,检查后发现爆口附近水冷壁管存在严重的壁厚减薄现象。对该水冷壁管进行宏观检查、化学成分分析、金相组织检验和硬度检验后可知,该水冷壁管发生爆管的原因是管外壁局部区域发生严重减薄,当剩余壁厚不能满足介质承载要求时,管道发生韧性开裂。水冷壁管外壁局部区域发生严重减薄是由于附近的周界风风箱发生泄漏,漏风点长期吹蚀该水冷壁管,使水冷壁管发生吹损减薄,从而引发水冷壁爆管。

A 600 MW supercritical boiler water-cooled wall tube(15CrMoG)had a tube burst failure accident.After inspection,it was found that there was a serious wall thickness reduction phenomenon in the water-cooled wall tube near the burst.After macroscopic inspection,chemical composition analysis,metallographic structure inspection and hardness inspection of the water-cooled wall tube,it could be seen that the reason for the explosion of the water-cooled wall tube was that the outer wall of the tube was severely thinned.When the residual wall thickness could not meet the requirements of medium bearing capacity,ductile cracking occurred in the pipeline.The serious thinning of the outer wall of the water-cooled wall pipe in some areas was due to the leakage of the surrounding air bellowed near the water-cooled wall pipe.The air leakage point blew away the water-cooled wall pipe for a long time,resulting in the blowing loss and thinning of the water-cooled wall pipe,resulting in the explosion of the water-cooled wall pipe.