Corrosion Resistance Optimization of Steel-Plastic Interface in Steel-Belt Corrugated Pipes ——Design for Buried Drainage Pipes Based on SY/T 4106 Standard

1. Research Background


Steel-belt corrugated pipes, with a "steel reinforcement + HDPE composite" structure (Figure 1), occupy 35% of the market for municipal drainage projects with burial depth >4m (2024 China Plastic Pipe Industry Report). While their ring stiffness reaches SN16, steel corrosion causes 41% of failures, especially in coastal saline-alkali soil (Cl⁻ >500mg/L) and industrial wastewater areas (pH <4).

2. Core Issue: Steel-Plastic Interface Failure Mechanism

2.1 Three-Stage Corrosion Process


Through salt spray testing (GB/T 10125-2021) and electrochemical analysis, steel corrosion proceeds as:
![Corrosion Process Schematic](Figure 2)


  • Initial Stage (0-6 months): Localized corrosion at HDPE coating pinholes
  • Medium Stage (6-24 months): Coating delamination due to rust expansion
  • Final Stage (>24 months): Structural collapse with >30% steel loss

2.2 Key Influencing Parameters


Parameter Industry Standard Field Measurement Influence
Galvanized layer thickness (μm) ≥85 70-80 ★★★★☆
Plastic bonding strength (MPa) ≥3.5 2.8-3.2 ★★★☆☆
Chloride ion concentration (mg/L) - 300-800 ★★★☆☆

3. Corrosion Resistance Experiments

3.1 Steel-Plastic Interface Modification


Developed "three-coat one-interface" technology (Figure 3):


  • Base Layer: 5μm Zn-Ni alloy plating (corrosion life +200%)
  • Interlayer: MAH-g-PE transition layer (bonding strength increased to 4.8MPa)
  • Top Layer: 2mm HDPE/nano-TiO₂ composite (UV resistance)

3.2 Corrosion Performance Comparison


Structure Type Salt Spray Life (h) Peel Strength (N/cm) Soil Applicability
Traditional galvanized 1500 32 General soil
Three-coat steel 5000 55 Saline-alkali, acidic soil
Pure plastic pipe >10000 - Non-reinforced scenarios

4. Engineering Solutions

4.1 Corrosion Grade Design Standard


Based on SY/T 0025-2018 soil corrosion classification:


Soil Type Corrosion Grade Steel 防腐 Requirements Recommended Pipe Type
General clay Low Galvanized ≥85μm SN8
Saline-alkali Medium Galvanized + epoxy coating SN12-SC
Industrial soil High Three-coat + cathodic protection SN16-SCC

4.2 Anticorrosion Construction Process


"Three Inspections One Control" ensures interface quality:


  1. Steel pretreatment: Sandblasting to Sa2.5 (GB/T 8923.1)
  2. Hot bonding: 230±5℃, 0.3-0.5MPa pressure
  3. Integrity test: Spark 检漏 (15kV, <1 defect/10m)

5. Field Test Case: Chemical Park Drainage Project


Index Traditional Pipe Optimized Pipe Standard Requirement
5-year steel corrosion (%) 18 3 ≤10
Joint delamination (times/year) 0.6 0 0
Predicted service life (years) 8-10 15-20 -

6. Future Technologies

6.1 Self-Healing Anticorrosion Coating


Embedded microcapsule inhibitors (Figure 4) release molybdate to repair <0.1mm corrosion pits.

6.2 Smart Corrosion Monitoring System


Integrated distributed potential sensors for real-time monitoring of:


  • Steel electrochemical potential distribution
  • Coating damage location (accuracy ±0.5m)


Conclusion
This paper solves corrosion issues through interface modification + process control + intelligent monitoring. As a professional supplier, we provide:
✅ Customized corrosion-grade pipes (SN8-SN16)
✅ Soil corrosion assessment services
✅ Third-party steel 防腐 testing reports


Keywords: Steel-belt corrugated pipe, steel-plastic composite pipe, corrosion resistance, buried drainage, SY/T 4106

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