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| Analysis on Current Leakage Failure of Insulation Joints of Buried Oil & Gas Pipeline |
| Received:March 21, 2021 Revised:March 30, 2021 |
| View Full Text View/Add Comment Download reader |
| DOI：10.7643/issn.1672-9242.2021.04.007 |
| KeyWord:insulation joint oil & gas pipeline current leakage failure cathodic protection corrosion products insulation performance |
| Author | Institution |
| SHI Zhan |
National Network Group Southwest Pipeline Co., Ltd., Chengdu , China |
| LAN Cai-fu |
National Network Group Southwest Pipeline Co., Ltd., Chengdu , China |
| WANG Bin-bin |
National Network Group Southwest Pipeline Co., Ltd., Chengdu , China |
| HUO Guan-liang |
National Network Group Southwest Pipeline Co., Ltd., Chengdu , China |
| WANG Xiang-yue |
National Network Group Southwest Pipeline Co., Ltd., Chengdu , China |
| YAN Mao-cheng |
Institute of Metal Research, Chinese Academy of Sciences, National Engineering Research Center for Corrosion Control, Shenyang , China |
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| Abstract: |
| Objective To analyze the cause of the leakage failure of the insulation joint of a certain pipe section of the Lanzhou-Chengdu-Chongqing product pipeline and its impact on the effectiveness of cathodic protection. Methods The potentiostat and the insulation performance of insulating joints in the pipeline cathodic protection system were tested using potential measurement, resistance test, and leakage rate test, etc. The back-field investigation and detection of the parameters such as the cathodic protection output and the potential for both ends of the insulating joint was carried out on the pipe section, and the composition and morphology of the corrosion products of the pipe at the failure location of the insulating joint were characterized. The results show that the output voltage difference between the potentiostat before pigging and after pigging is 7.55 V, and the leakage rate of the protection side and the non-protection side is 90%. There is a large amount of pitting in the pipe sections at both ends of the insulation joint, and the depth can reach 3~3.5 mm. A large number of corrosion products are on the insulating joint gasket, mainly including Fe3O4, FeOOH and other magnetic and conductive iron oxides. Conclusion The failure of the insulation joint causes the pipeline to lose its protection. The first reason is that the outer anti-corrosion layer is damaged, and the external conductive medium will cause the pipeline to overlap; the second reason is that the magnetic conductive corrosion product inside the pipeline causes the insulation joint to be short circuited. |
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