在长输管道接地系统应用惰性材料的危害
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摘要
在长输管道的场站、阀室接地系统中,常使用惰性材料做接地极或降阻剂,包括铜包钢、高效接地模块(石墨)和化学降阻剂(含石墨粉)等。惰性材料做接地极或降阻剂,有着良好的导电性,同等施工条件下,有着较小的接地电阻,但是,惰性材料与接地网之间存在电偶腐蚀,川气东送管道多个RTU和手动阀室陆续出现接地电阻逐渐变大的现象。经过调查研究和现场开挖验证,接地网腐蚀严重。并且川气东送管道阀室与主管道之间未安装绝缘法兰,且主管道与接地之间存在断路现象,惰性材料泄漏大量管道阴极保护电流,阀室附近主管道电位不达标,且在主管道与惰性接地材料之间存在电偶腐蚀,主管道作为腐蚀电池的阳极,加速腐蚀,反向保护接地材料,对主管道而言,存在巨大的腐蚀穿孔隐患。
Inert material is frequently used as grounding electrode or resistance reducing agent,including copper clad steel, high-efficiency grounding module( graphite) and chemical resistance reducing agent( including graphite powder), in the field station and valve room of long-distance pipeline grounding systems.Inert material used as grounding electrode or resistance reducing agent, has good electrical conductivity. Under the same construction conditions, it has a small grounding resistance. However,there is galvanic corrosion between the inert material and the grounding grid. The grounding resistance has gradually increased on many RTU and manual valve room of the Sichuan-East Gas pipeline. After investigation and field excavation verification, the grounding grid is seriously corroded. And there is no insulation flange between the pipeline chamber and the main pipeline of the Sichuan-East Gas Pipeline.There is an open circuit between the main pipeline and the grounding. The inert material leaks a large amount of cathode protection current of the pipeline and the potential of the main pipeline near the valve chamber is not up to standard. Meanwhile, there is galvanic corrosion between the main pipeline and the inert grounding material. The main pipeline acting as the anode of the corrosion battery accelerates corrosion and reversely protects the grounding material. For the main pipeline, there is a huge potential for corrosion perforation.
Inert material is frequently used as grounding electrode or resistance reducing agent,including copper clad steel, high-efficiency grounding module( graphite) and chemical resistance reducing agent( including graphite powder), in the field station and valve room of long-distance pipeline grounding systems.Inert material used as grounding electrode or resistance reducing agent, has good electrical conductivity. Under the same construction conditions, it has a small grounding resistance. However,there is galvanic corrosion between the inert material and the grounding grid. The grounding resistance has gradually increased on many RTU and manual valve room of the Sichuan-East Gas pipeline. After investigation and field excavation verification, the grounding grid is seriously corroded. And there is no insulation flange between the pipeline chamber and the main pipeline of the Sichuan-East Gas Pipeline.There is an open circuit between the main pipeline and the grounding. The inert material leaks a large amount of cathode protection current of the pipeline and the potential of the main pipeline near the valve chamber is not up to standard. Meanwhile, there is galvanic corrosion between the main pipeline and the inert grounding material. The main pipeline acting as the anode of the corrosion battery accelerates corrosion and reversely protects the grounding material. For the main pipeline, there is a huge potential for corrosion perforation.
引文
[1]冯洪臣.《管道阴极保护-设计安装运行维护》(第三版2017.01)北京:化学工业出版社, 2017.
[2]黄留群等. GB\T 21448-2017埋地钢质管道阴极保护技术规范,北京:中国标准出版社, 2017.
[2]黄留群等. GB\T 21448-2017埋地钢质管道阴极保护技术规范,北京:中国标准出版社, 2017.