某天然气管道三通开裂原因分析

Cause Analysis on Cracking of Tee for a Natural Gas Pipeline

某天然气管道三通在进行定期磁粉检验时发现表面出现裂纹。采用化学成分分析、力学性能试验、硬度测试、宏观分析、断口分析、金相检验及能谱分析等方法对三通的开裂原因进行了分析。结果表明:该天然气管道三通的金属氧化物在直缝钢管高频焊接时的挤压过程中未能排出,长条状氧化物夹杂沿熔合线分布,降低了母材结合力,最终导致该三通在使用过程中发生应力开裂。

Cracks were found on the surface of tee of a natural gas pipeline during regular magnetic particle inspection.The cracking causes of tee were analyzed by means of chemical composition analysis,mechanical property test,hardness test,macro analysis,fracture analysis,metallographic examination and energy spectrum analysis.The results show that the metal oxide of the tee for the natural gas pipeline could not be squeezed out during the extrusion process of high frequency welding of straight seam steel pipe.The distribution of long strip oxide inclusions along the fusion line reduced the bonding strength of the base metal,and finally led to the stress cracking of the tee in service.