某石化公司催化重整装置预加氢单元管道弯头发生了破裂。采用宏观观察、壁厚测量、化学成分分析、力学性能试验、金相检验、断口形貌分析、X射线衍射分析及厚度计算等方法对弯头的破裂原因进行了分析。结果表明：该预加氢单元弯头在酸性HCl-H₂S-NH₃-H₂O腐蚀环境下，不仅发生环境腐蚀，亦受到物料及脱落腐蚀产物冲刷，腐蚀与冲刷相互促进，造成弯头外弧侧壁厚减薄严重，最终导致该部位承压能力不足而出现局部破裂。

The pipe elbow of pre-hydrogenation unit in catalytic reforming unit of a petrochemical company was split. The splitting causes of the elbow were analyzed by means of macroscopic observation, wall thickness measurement, chemical composition analysis, mechanical property test, metallographic examination, fracture morphology analysis, X-ray diffraction analysis and thickness calculation. The results show that the elbow of pre-hydrogenation unit not only had environmental corrosion, but also was scoured by materials and exfoliated corrosion products under the acidic HCl-H₂S-NH₃-H₂O corrosive environment. Corrosion and scour promoted each other, resulted in serious wall thickness thinning of the outer arc side of the elbow, which eventually led to local splitting due to insufficient bearing capacity.