Cathodic protection of buried oil and gas pipelines
Time:
Jan 20,2022
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When the pipe crossing the railway and highway adopts casing, whether it is steel casing or concrete casing, there will be shielding effect, so that the external cathodic protection current will not reach the transmission pipe in the casing and become the blind area of cathodic protection. Once the casing enters water, the pipeline in the blind area will not be protected. For the shielding of the casing, the strip zinc anode is usually used, which is spirally wound on the pipeline and welded with the pipeline every 2m or so. Test piles should be installed at every casing, and the test wires on the casing and the pipeline can be easily tested on the ground.
When arranging sacrificial anode on the pipeline, some special conditions should be taken into account, and the overall design should be adjusted. For example, when the protection radius of sacrificial anode is not enough at the crossing soil access point of directional drilling, the number of anodes or the specification of anodes can be increased at the crossing soil access point to fully protect the crossing pipeline. There are two ways of embedding sacrificial anode: vertical and horizontal. The vertical anode adopts the drilling method to bury the anode in the direction perpendicular to the pipeline. This method does not require large-area excavation, but the protection effect is not as good as the horizontal anode, which is suitable for the built pipeline. The horizontal anode is constructed by slotting method. When laying the pipeline, it is placed in the same trench with the pipeline, which will save the cost of separate excavation and achieve good protection effect. The anode position is generally 3-5m away from the outer wall of the pipeline, and the minimum should not be less than 0.3m. However, due to the convenience of laying in the same trench, the spacing is generally controlled to 0.3-0.5m, leaving a certain operation space, the buried depth should be no less than 1m from the top of the anode to the ground. When arranged in groups, the anode spacing should be 2-3m.
Jiaozuo Furuixin Nonferrous Metals Co., Ltd. produces and manages products such as magnesium alloy sacrificial anode, zinc alloy sacrificial anode, aluminum alloy sacrificial anode, deep well anode, zinc grounding battery, precious metal oxide anode, magnesium belt, zinc belt, insulated joint, zinc grounding battery, potentiostat, test pile, reference electrode and other cathodic protection supporting products. Tel: Manager Zhang 15138020202
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