加氢裂化装置新氢压缩机出口排凝K101B阀侧短管在使用中出现开裂, 通过宏观和微观检验、化学成分分析、硬度测试和能谱分析等方法对开裂原因进行了分析。结果表明: 由于短管焊接结构上存在几何不连续性, 结构的截面变化幅度较大, 产生了严重的应力集中, 在短管焊接热影响区魏氏组织最薄弱的地方形成了裂纹源, 在交变载荷的共同作用下裂纹逐渐扩展, 最终导致瞬时断裂。最后提出了相应的预防措施。

The pipe nipple on the side of K101B valve of one hydrogenation splitting equip exit was cracked in use. The cracking reason was analyzed by means of macroscopic and microscopic examination, chemical composition analysis, hardness testing, energy spectrum analysis and so on. The results showed that there was geometrical discontinuity in pipe nipple welded construction, the change of construction section was large, led to severe lateral stress concentration. Widmanstatten structure was the weakest in heat affected zone, where the crack initiated and extended under the alternating load, and led to break at last. Then the measures were put forward.