Key Technical Requirements for Galvanized Pipes

Key Technical Specifications for Galvanized Pipes in Hainan

Surface Quality Requirements

The pipe surface shall be smooth and free from visible defects including:
• Zinc nodules
• Burrs
• Uncoated areas (bare spots)
• Black spots
• Air bubbles

Zinc coating must demonstrate:
• Uniform distribution
• Continuous coverage
• Consistent coloration

Dimensional Tolerances

Outside Diameter (OD):
≤40mm OD:±0.5mm

40mm OD:±1% of nominal diameter

Wall Thickness:
±10% of nominal thickness (e.g., 4.0mm nominal:3.6-4.4mm range for 100mm OD pipe)

Length:
Standard/bundled lengths with ±20mm tolerance

Zinc Coating Specifications

Thickness Criteria:
Hot-dip galvanized:
• ≤60.3mm OD:≥85μm average
• >60.3mm OD:≥90μm average
Electro-galvanized:10-50g/m²

Adhesion Testing:
• Pass wrap-around or cross-cut tests without peeling/flaking

Uniformity Verification:
• Withstand specified CuSO₄ immersion cycles (e.g., 5 tests)
• No copper deposition observed

Mechanical Properties

Tensile Strength:
Q235 grade:≥375MPa

Yield Strength:
Q235 grade:≥235MPa
(Higher grades proportionally increased)

Elongation:
Minimum 20% to ensure ductility

Chemical Composition
Base material (carbon structural steel) must comply with GB standards:

Carbon (C):0.12-0.20%

Manganese (Mn):0.30-0.65%

Sulfur (S)/Phosphorus (P):≤0.045% eachhttp://www.hnftsteels.com