X80钢管螺旋焊缝裂纹原因分析  

Cause of Crack in Spiral Weld of X80 Steel Pipe

作　　者：赵康 ZHAO Kang(Petrochina West Pipeline Company,Urumuqi,Xinjiang 830000,China)

机构地区：[1]中石油管道有限责任公司西部分公司,新疆乌鲁木齐830000

出　　处：《石油管材与仪器》2020年第6期66-69,共4页Petroleum Tubular Goods & Instruments

摘　　要：某在役X80输气管道发现螺旋焊缝内表面存在裂纹,为了确定该裂纹的形成原因,对含裂纹螺旋焊缝进行了无损检测、宏观检测、水压试验、扫描电镜分析、金相分析。试验分析结果表明,该裂纹为焊缝内表面裂纹,长度为64 mm、深度为15 mm,含裂纹钢管的承载能力为23.5 MPa。该裂纹由钢管螺旋缝焊接原始缺陷引起,在工厂水压或现场水压试验时扩展形成。焊接原始缺陷为熔合不良或焊接热裂纹,该原始缺陷在工厂检测时被发现,并进行补焊,但补焊未将原始缺陷全部清除。建议加强工厂焊缝补焊和无损检测的质量控制。A crack was found on inner surface spiral weld of a X80 pipe in service.After cutting this pipe from gas transmission pipeline,nondestructive testing,macroscopic examination,hydrostatic pressure test,scanning electron microscope analysis and metallographic analysis were performed on this pipe.It is found that the crack lies in the inner surface.Crack length is 64 mm and depth is 15 mm.Hydrostatic pressure test shows the leak pressure of this cracked pipe is 23.5 MPa.The crack is caused by original defect in spiral welding process in pipe factory.The original weld defect was propagated during hydraulic pressure test in the factory or in pipeline field.The original welding defect was poor fusion or hot crack,which was found during factory inspection.External repair welding was done on this defect,but the repair welding did not completely remove the original defect.It is suggested that repair welding and NDT process should be more careful.

关 键 词：X80 钢管 螺旋焊缝 补焊 裂纹 

分 类 号：TG404[金属学及工艺—焊接]