针对输气管道在线检测过程中发现的管壁异常减薄，采用金属磁记忆、声发射、声定位超声波C扫描、数字X射线等系列技术对异常处进行了检测与验证，综合各种检测结果判定该处缺陷为钢管自身冶金缺陷(可能为夹杂类分层缺陷)，不是天然气造成的腐蚀缺陷，在加强监测的情况下该钢管仍可使用。

For the abnormal wall thickness reduction of transportation pipelines in service, a combination of testing methods of magnetic memory, acoustic emission, ultrasonic C-Scan and X-Ray inspection technologies was used to explore its cause. Conclusion was drawn that the defect was defined as metallurgical imperfections caused during smelting and rolling the tube(analogous to delamination flaws of tramp metal), which was not corrosion defects. The tubes could be serviceable under the condition of strengthening their monitoring timely.