长输管道阀室接地网腐蚀状况检测及原因分析

Corrosion Detection and Cause Analysis of Grounding Grid in Valve Chamber of Long Distance Pipeline

油气阀室的接地网是保护阀室电气设备和人员安全的重要设施,随着我国西气东输的发展,油气管道越来越多,管道阀室接地腐蚀情况越来越严重。本研究对4个油气管道阀室的接地网进行了调研,发现均存在不同程度的腐蚀情况。为了探明造成接地网腐蚀的主要原因,测量了这些阀室的地网接地电阻、土壤电阻率、接地体极化电位以及土壤理化参数。研究发现这些阀室的土壤微生物腐蚀属于微弱等级,也排除了自然环境引起接地体严重腐蚀的可能性。最后,通过分析这4个阀室的排流情况和接地扁钢的腐蚀特征,提出直流电流腐蚀是造成接地网腐蚀的主要原因。这些阀室距最近的直流接地极在60 km以上,计算得到的镀锌扁钢年腐蚀损失质量并不大,但当直流输电线路单极——大地运行时,如果直流腐蚀电流集中在接地扁钢的局部点位置,依然会造成接地扁钢的断裂,使得油气阀室的接地网失效。本文的研究成果可为阀室接地网的改造提供依据。

Grounding grid of oil and gas chamber is an important facility to protect the safety of electrical equipment and personnel in valve chamber.With the development of West-to-East gas transmission in China,there are more and more oil and gas pipelines,and the corrosion of valve chamber is becoming increasingly serious.The investigation and research on four oil and gas pipeline valve chamber grounding networks have been conducted,and it is found that there are different degrees of corrosion situation.By measuring the parameters of soil fixed earthing resistance,earthing electrode potential and soil parameters,the ph value analysis and evaluation,the author found that soil microbial corrosion belongs to the weak level.The possibility of severe corrosion of grounding body caused by natural environment is excluded.By analyzing the discharge of the four valve chambers and the corrosion characteristics of grounding flat steel,it is suggested that DC current corrosion is the main cause of grounding grid corrosion.The valve chambers are located more than 60km away from the nearest DC grounding electrode,although computed galvanized flat steel corrosion loss quality is not large,in dc transmission line unipolar-if the DC corrosion current is concentrated at a local point of the grounding flat steel,it will still cause the fracture of grounding flat steel;this is the main reason for the failure of valve chamber ground network.The research results provide a basis for the modification of valve chamber grounding grid.