Depending on macroscopical shape, micro - structure, chemical composition analysis, mechanical performance test, crack apperance observation and corrosive composition, the cause of cracking for joint pipes of natural gas end station was analyzed. The result showed that the joint pipe crack including surface crack and hided crack occurred at the welding area, the property of crack were hydrogen induced cracking and stress oriented hydrogen induced cracking. Inferior anticorrosion coat at the equipment inner , surface is the main reason for cracking generating, another improper welding process accelerates cracking development obviously.%对开裂的天然气集气末站汇管进行了宏观形貌、显微组织、化学成分分析和力学性能测试、断口形貌观察以及腐蚀产物相组成确定,对其开裂原因进行了分析.结果表明:集气末站汇管开裂裂纹位于汇管的焊缝区,裂纹分为表面裂纹与隐藏裂纹,裂纹性质属氢致开裂和应力导向氢致开裂；设备内壁防腐涂层质量低劣是导致开裂的主要原因,焊接工艺不当对开裂有明显的促进作用.
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