Analysis of Cathodic Protection Schemes Using Magnesium Alloy Sacrificial Anodes in Three Scenarios: Storage Tanks, Reservoir Gates, and Natural Gas Pipelines

I. Cathodic Protection with Magnesium Anodes for Storage Tanks

1. Applicable Scenarios

• Protection of Tank Bottom External Wall: The bottom of buried storage tanks is susceptible to soil corrosion; magnesium anodes provide uniform protection.
• Localized Protection of Tank Wall: Weak areas such as weld points and coating damage.
• Environmental Requirements: Suitable for neutral or weakly alkaline soils with resistivity >50 Ω·m.

2. Selection Recommendations

• Specification Selection:
  • Large storage tanks (e.g., 100,000 m3): 22kg or 14kg magnesium anodes, spaced 5-10 meters apart.
  • Small to medium storage tanks: 11kg or 8kg anodes, spaced 3-5 meters apart.
• Alloy Type:
  • High-potential magnesium alloys (e.g., AZ63 type): Driving voltage 0.85V, suitable for high-resistivity soils.
  • Low-potential magnesium alloys (e.g., Mg-Mn type): Avoid over-protection, suitable for medium-resistivity environments.

3. Installation Key Points

• Position Design:
  • Anodes evenly distributed around the tank bottom periphery, 1-3 meters from the tank wall, buried depth ≥1 meter.
  • Magnesium anodes are strictly prohibited inside the tank (to prevent electrolyte contamination).
• Backfill Material Usage:
  • Wrap anodes with gypsum powder + bentonite to reduce grounding resistance to <10Ω.
• Cable Connection:
  • Use VV-10mm2 cable, connect tank and anode via thermite welding, insulation resistance >1MΩ.

II. Sacrificial Anodes for Reservoir Gates

1.&amp;nbsp;Applicable Scenarios

• Submerged Parts of Steel Gates: Long-term immersion in freshwater or slightly saline water environments.
• Gate Embedded Parts: Corrosion-prone components such as rails and lifting lugs.
• Environmental Limitations: Water temperature ≤45℃ to avoid accelerated self-corrosion of magnesium anodes due to high temperatures.

2.&amp;nbsp;Selection Recommendations

• Specification Selection:
  • Large gates: 22kg or 14kg anodes, installed singly or in parallel.
  • Small gates: 11kg or 8kg anodes, spaced 2-3 meters apart.
• Alloy Optimization:
  • Mg-Al-Zn-Ca alloy with added calcium (e.g., the new alloy mentioned in Abstract 1), current efficiency >60%, with improved corrosion resistance in freshwater.

3.&amp;nbsp;Installation Key Points

• Mounting Method:
  • Weld or bolt to the back of the gate, avoiding areas of water flow impact.
  • Backfill material must be soaked during installation to ensure conductivity.
• Cable Sealing:
  • Seal connections with epoxy resin to prevent water infiltration and short circuits.

III. Magnesium Alloy Sacrificial Anodes for Natural Gas Pipelines

1.&amp;nbsp;Applicable Scenarios

• Long-Distance Pipeline Trunk Lines: High-resistivity soils (>50 Ω·m) or freshwater areas.
• Pipeline Bends and Valves: Localized areas prone to turbulent flow corrosion.
• Environmental Limitations: Avoid use in high temperatures (>45℃) or dry soils.

2.&amp;nbsp;Selection Recommendations

• Specification Selection:
  • Main pipelines: 22kg or 14kg anodes, spaced 50-100 meters apart.
  • Branch pipelines: 11kg anodes, spaced 30-50 meters apart.
• Alloy Type:
  • AZ63 magnesium alloy: High driving voltage, suitable for high-resistivity environments.
  • Pre-packaged anodes: Built-in backfill material to simplify construction.

3.&amp;nbsp;Installation Key Points

• Burial Requirements:
  • Place 3-5 meters from the pipeline, buried depth ≥1 meter, parallel to the pipeline.
  • Backfill soil must be compacted to avoid voids affecting conductivity.
• Test Station Setup:
  • Install test stations every 500 meters to monitor potential and current distribution.