目的 找出导致外防腐层破损的因素，研究防腐层破损对管道壁厚减薄的影响。方法 采用PCM+埋地管道外防腐层状况检测仪对管道外防腐层进行检测，采集埋深、DB值和电流衰减值，并根据电流值计算绝缘电阻率。采用超声波测厚仪检测管道剩余壁厚，通过现场实测数据对管道防腐层和管壁腐蚀情况进行分析。结果 通过对数据的分析，发现运行年限、埋深、介质输送温度以及土壤电阻率等因素都对外防腐层产生不同程度的影响。不同材质的外防腐层随着运行年限的增长，其破损程度变化不同，并且对管道壁厚减薄程度的影响也不同。 结论 对于运行超过10年的管道，应定期检测并及时维修、更换防腐层。埋深不足0.8 m的管道，应及时增加覆土层厚度，无法加大埋深的则应该加大巡检力度，防止管道遭到破坏。运行超过10年的沥青玻璃布管道外防腐层破损严重，建议更换3PE防腐层。应建立起阴极保护系统，与外防腐层形成双层屏障。

Objective To identify the cause of outer coating damage factors and the effect of damaged anticorrosive coating on thickness reduction of the pipe wall. Methods PCM + buried pipeline external coating condition detector was used to detect the pipeline external coating, collect burial depth, DB value and current attenuation value and calculate insulation resistance rates based on the current value. Remaining wall thickness of the pipeline was detected by ultrasonic thickness meter. Pipeline coatings and wall corrosion conditions were analyzed based on the field data. Results According to data analysis, operating years, burial depth, medium transmission temperature and soil resistance rates, etc. all had different degrees of impact on external anticorrosive coating. Different materials of external anticorrosive coating had different degrees of damage and different impact on thickness reduction of pipe wall with the growth of its operating years. Conclusion Pipeline that has run for more than one decade should be regularly checked and maintained and its anticorrosive coating should also be regularly replaced. For the pipeline with depth less than 0.8 m, the overburden thickness should be increased in time. If the depth can not be increased, inspection should be intensified to avoid pipeline damage. As asphalt glass cloth that has run for more than one decade is damage extensively, the anticorrosive coating should be replaced with 3PE coating. Cathodic protection system should be established to form a double barrier with the external anticorrosive coating.