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How Thick Must a Solar Mount’s Galvanized Layer Be for 25+ Year Durability?

Solar mounting system quality directly impacts PV plant ROI. Carbon steel (Q235/Q345) with hot-dip galvanizing (HDG) is widely used, but inadequate zinc thickness remains a common failure point. This guide provides data-driven thickness requirements for 25-year corrosion resistance.

Why HDG Thickness Matters


HDG is a critical barrier against corrosion. Key factors affecting zinc thickness include:

  • Base material composition
  • Surface roughness
  • Material internal stress
  • Geometry
    Base steel thickness directly influences HDG thickness.

Minimum HDG Thickness Standards


Per China National Standard GBT13192-2002:

  • Base Steel: 2.0mm
    • Minimum local thickness: 45μm
    • Minimum average thickness: 55μm

Corrosion Lifespan by Environment


*(Based on Japan HDG Association exposure tests, 1964-1974)*
Using 55μm average thickness (396g/m² zinc coating):

EnvironmentService Life (Years)Annual Corrosion (μm)
Heavy Industrial8.9140.1
Coastal32.6710.8
Rural66.335.4
Urban20.7917.5

25-Year Requirement Calculation


To achieve 25-year lifespan:

  • Heavy Industrial: ≥139μm (40.1μm/yr × 25)
  • Coastal: ≥37.5μm (10.8μm/yr × 25)
  • Urban: ≥60.76μm (17.5μm/yr × 25)
  • Rural: ≥18.75μm (5.4μm/yr × 25)

Engineering Recommendations

  1. Urban Rooftop Systems: Minimum 65μm average HDG thickness
  2. Heavy Industrial Areas: Increase base steel thickness + zinc coating
  3. High-Corrosion Sites: Specify ≥80μm HDG for critical components

Premium Material Specifications


For maximum durability:

  • Steel: Q235 with 80μm average HDG coating
  • Aluminum: AL6005-T5 (12-15μm anodized)
  • Stainless Steel: SUS304
    *Result: >30-year lifespan, 42m/s wind load, 1.4KN/m² snow load.*

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