1. Technical Solutions and Objectives

The West-East Natural Gas Pipeline Project adopts an integrated cathodic protection system that combines the forced current method and the sacrificial anode method.        Designed for a total pipeline length of nearly 3,900 km, this system mitigates high corrosion risks caused by varying soil resistivity and DC/AC interference, ensuring a safe operational life of over 30 years under complex environmental conditions.

The system features combined protection between the external anti-corrosion coating and cathodic protection circuits.        In remote areas without access to grid electricity, a solar photovoltaic power supply system is introduced to maintain stable current output.

2. Core Protection Measures

2.1 Forced Current Cathodic Protection

Dedicated cathodic protection stations are equipped with potentiostatic control devices and auxiliary anodes.        Depending on environmental requirements, high-silicon cast iron anodes or flexible anodes are utilized.

• Minimum protection current density: 4 μA/m²

• Protection potential range: -0.85V to -1.25V (CSE)

In non-electrified areas such as Gansu and Shaanxi, a solar photovoltaic power system replaces the traditional power source.        By integrating TEG (thermoelectric generator) and CCVT (capacitance-coupled voltage transformer) technology, continuous cathodic protection operation is ensured in remote regions.

2.2 Sacrificial Anode Assisted Protection

In sections with high soil resistivity or interference risk (e.g., river crossings, railway intersections), magnesium alloy sacrificial anodes are installed.        Ground resistance is reduced using coke powder filler with coating materials. The anodes preferentially corrode to protect the steel pipeline, with spacing designed between 3–5 meters.

2.3 Anti-Corrosion Layer Joint Protection

The pipeline’s exterior features multiple anti-corrosion coatings tailored for environmental demands:

• Three-layer polyethylene (3PE) for harsh natural conditions

• Double-layer fusion-bonded epoxy (FBE) for strong corrosion resistance

• Enhanced FBE coatings for standard environments to isolate corrosive media

3. Technological Innovation and O&M Strategy

3.1 Material and Process Optimization

The introduction of flexible anodes made from conductive plastic materials accommodates pipeline bending requirements, reduces anode consumption, and simplifies installation.

The use of controlled rolling and cooling process steel (e.g., X70 grade steel) improves strength, toughness, and weldability, while lowering carbon equivalent and extending the base material’s lifespan.

3.2 Intelligent Monitoring and Maintenance

An in-situ corrosion monitoring system continuously collects data on pipeline potential and current density.        These parameters are dynamically adjusted through a centralized control platform. The system’s performance has been validated through power-failure testing.

For aging equipment (such as potential transmitters and potentiostats operating for over 20 years), retrofitting projects replace failed reference electrodes and restore remote transmission functions to maintain monitoring accuracy.

4. Implementation Results and Ecological Protection

4.1 Project Results

• Cathodic protection coverage exceeds 98%

• Pipeline corrosion rate reduced below the safety threshold

• Service life of pipelines significantly extended

The solar power system successfully supports cathodic protection operations in non-electrified western regions, reducing carbon emissions and improving energy efficiency.

4.2 Ecological Protection Measures

When crossing ecologically sensitive areas such as the Anxi Extreme Dry Desert Reserve in Gansu Province, scientific route selection, green construction, and ecological restoration measures are implemented to minimize vegetation damage.

The project sets a national benchmark for long-distance pipeline corrosion protection. Its combined “joint protection + intelligent operation and maintenance” model provides a valuable reference for global energy infrastructure projects.