接地导致埋地管道阴极保护失效的应对措施

1. 中石化川气东送天然气管道有限公司;2. 山东省中远天然气技术服务有限责任公司

长输管道;阴极保护;接地导通;绝缘失效;欠保护

Countermeasures for cathodic protection failure of buried pipelines caused by grounding
LI Gangchuan1, DENG Tongjun1, WANG Lian2, LI Qilin1

1. SINOPEC Sichuan to East Gas Pipeline Co. Ltd.; 2. Shandong Zhongyuan Natural Gas Technical Services Co. Ltd.

long-distance pipeline, cathodic protection, grounding conduction, insulation failure, lack of protection

DOI: 10.6047/j.issn.1000-8241.2019.12.009

备注

为了查明川气东送天然气长输管道诸多阀室及邻近管段强制电流阴极保护失效、常年处于欠保护状态的原因,以其某RTU阀室为例,建立了阀室局部阴极保护的简单物理模型,通过模型推导与现场测试验证相结合的方法,得出管道与接地网导通诱发绝缘失效是导致管道欠保护的直接原因。在查找管道绝缘失效原因并进行定位的过程中,发现了长输管道阴极保护和防雷接地系统在设计、建造、运行维护期间的诸多问题,提出管道绝缘失效整改及保护电位恢复应采取电路隔离、牺牲阳极接地极改造、区域牺牲阳极热点保护、区域强制电流阴极保护等应对措施。(图4表4,参[20]

To find out the causes of the impressed current cathodic protection failure in valve chambers and adjacent pipes,as well as the resulting long-term lack of protection in Sichuan-to-East long-distance natural gas transmission pipeline, asimple physical model of partial cathodic protection in valve chambers was established based on a case study of RTU valvechamber. Through the method of model deduction in combination with field test verification, it can be concluded that theinsulation failure, which is caused by conduction between pipeline and grounding grid, should be the direct cause of lack ofprotection. During the process of finding the causes of pipeline insulation failure and positioning, many problems, existingin design, construction, operation and maintenance of cathodic protection and lightning protection grounding system forlong-distance pipelines, were exposed. Countermeasures, such as circuit isolation, grounding electrode modification bysacrificial anode, regional hot spot protection by sacrificial anode, and regional cathodic protection by impressed current,have been proposed for the rectification of pipeline insulation failure and restoration of protection. (4 Figures, 4 Tables,20 References)

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