输油管道绝缘接头失效原因分析

Failure analysis of insulating joint in oil pipeline

为了弄清输油管道绝缘接头失效的原因,通过宏观形貌分析、理化检测、金相显微、扫描电镜等手段对其进行研究分析。绝缘接头用焊接金属环替代了整体式锻造结构,结果表明:右凸缘法兰对裂纹较为敏感;接头短管、左凸缘法兰、接头外层金属维氏硬度存在差别;金相组织为铁素体(Ferrite)+珠光体(Pearlite)。该绝缘接头泄漏的主要原因为实际结构不符合SY/T 0516—2016整体型绝缘接头要求,导致右凸缘法兰的剪切强度不够引起撕裂失效。

In order to find out the reason for the failure of the insulating joint in oil pipeline,this paper studied and analyzed the leakage accident by means of macroscopic appearance,physical and chemical examination,metallographic microscopy,and scanning electron microscope.The integral forging structure was replaced by the welded metal ring.The results show that the right flange was more sensitive to cracks.The vickers hardness of the joint short pipe,left flange and joint outer metal was different.The metallographic structure was Ferrite+Pearlite.The main reason of the failure is that the actual structure does not conform to the requirements for integral type insulating joint in SY/T 0516—2016 standard,which makes the tearing failure caused by the insufficient shear strength of the right flange.