空分高压氧温度计套管断裂原因分析

Analysis on fracture of hyperbaric oxygen thermowells of air separation unit

针对空分装置∅24 mm的06Cr17Ni12Mo2双金属温度计套管在吹扫时发生的焊缝根部断裂现象进行了试验,重点分析了根部焊缝的化学成分、显微组织、力学性能、断口形貌、共振模拟试验等方面的内容。结果表明,断裂原因与焊接没有太大关系;主要原因是在吹扫时,由于3支温度计套管排列在同一条直线上,在吹扫流速不断变化过程中温度计套管产生横向共振和纵向共振,从而诱发温度计套管发生扭转疲劳脆断。后期通过增加温度计套管的直径、严格控制吹扫流速来控制共振的发生,从而消除了断裂现象。

Test was carried out for the occurred weld root fracture phenomenon of∅24 mm 06Cr17Ni12Mo2 bimetallic thermowells during purging,and chemical composition,microstructure,mechanical properties,fracture morphology,resonance simulation test and other aspects of root weld were analyzed.The results showed that the reason for fracture had little to do with welding.The main reason was that three thermowells were arranged in the same straight line during purging,and thermowells produced transverse resonance and longitudinal resonance during the constant change of purging flow rate,which induced torsional fatigue brittle fracture of thermowells.In the later stage,the resonance was controlled by increasing diameter of thermowells and strictly controlling purge flow rate,thus eliminating the fracture phenomenon.