Pei Yingying     1862587    9268

Sacrificial anodes are typically only economically applied to structures with low protective current requirements and in environments with low soil resistivity. Additionally, they are valuable when there is no power supply available or when it is economically unfeasible.
The materials used for sacrificial anodes in soil are primarily magnesium, while in seawater, zinc and aluminum are used. To maintain stable current output and reduce anode grounding resistance, chemical backfill should be used around sacrificial anodes in soil. This backfill is mainly composed of 75% calcium sulfate, 20% bentonite, and 5% sodium sulfate. Sacrificial anodes should not be buried in coke. When used in groups, the distance between anodes should be at least 3m. The soil cover thickness above the anode should be at least 0.6m. To measure the off-potential, sacrificial anodes should be connected to the pipeline through a test station. When sacrificial anodes are used near AC traction systems, the continuous AC induced voltage on the anode body should not exceed 20V.

1.Bagged sacrificial anodes should be backfilled with appropriately compacted material. When anodes and specialized backfill are supplied separately, the anode should be placed at the center of the backfill, and the backfill should be compacted before backfilling. Care should be taken in all operations to ensure that the wires and connections are not damaged. To avoid tensile stress, the wires should have sufficient slack.

2. At locations where bracelet anodes are used, the pipeline coating beneath the anode should be free of defects. When installing bracelet anodes, care should be taken to avoid damaging the coating. If concrete is sprayed onto the pipeline, all concrete on the anode surface should be removed. If reinforced concrete is used, metal contact between the anode and the reinforcement mesh or between the reinforcement mesh and the pipeline is strictly prohibited.
3. At locations where bagged anodes are used, they can be buried by trenching or plowing, with or without chemical backfill as required, typically parallel to the section of the protected pipeline.

Pei Yingying    1862587    9268