Galvanized Welded Pipe: Durable Corrosion Protection for Industrial & Structural Applications.
Engineered for Longevity: Hot-Dip vs. Electroplated Zinc Coatings
Galvanized welded pipes utilize Z275-Z450 hot-dip coatings (50–85 µm) to achieve 2,000+ hours of salt spray resistance (ASTM B117), outperforming cold-galvanized alternatives by 8–10x. The Fe-Zn alloy bonding layer formed at 435–455°C ensures 35–50 MPa adhesion strength (ISO 2409), ideal for water treatment plants, offshore rigs, and highway guardrails exposed to pH 4–10 environments.
Certifications & Key Advantages
- ASTM A53 & EN 10219 Certified: Compliant with JIS G3444 and GB/T 3091 standards.
- Cost Efficiency: 30% lower lifetime costs vs. stainless steel 316L.
- Custom Sizing: Thickness 0.1–300 mm (±0.15 mm), OD up to 1,200 mm.
- MOQ 3 Tons: HDG (hot-dip) or electroplated (EG) finishes available.
Technical Specifications
Mechanical Properties
| Property | Value | Test Standard |
|---|---|---|
| Yield Strength | 235–355 MPa | ISO 6892-1 |
| Tensile Strength | 370–500 MPa | ASTM E8/E8M |
| Elongation (A50) | ≥20% | EN ISO 6892-2 |
| Zinc Coating | 50–85 µm (Z275-Z450) | EN 1461 |
Material Composition:
- Carbon (C): 0.12–0.20%
- Manganese (Mn): 0.30–0.65%
- Silicon (Si): ≤0.30%
Coating Process:
- Pickling: HCl solution (10–15%) removes mill scale (ISO 8501-1 Sa2.5).
- Fluxing: ZnCl₂-NH₄Cl bath prepares surface for Fe-Zn bonding.
- Galvanizing: 435–455°C immersion for 3–8 minutes.
Dimensional Tolerances
| Parameter | Tolerance |
|---|---|
| Wall Thickness | ±10% of nominal size |
| Outer Diameter | ±1% of OD |
| Straightness | ≤2 mm/m |
Applications
- Construction: Scaffolding, roof trusses, and sewage systems.
- Utilities: Municipal water pipelines, gas distribution networks.
- Energy: Solar farm mounting systems, geothermal steam lines.
- Transport: Bridge crash barriers, railway signal posts.
Fabrication Guidelines
- Cutting: Plasma arc (speed ≤1.2 m/min for HDG).
- Welding: Use E7018 electrodes (preheat 100–150°C).
- Bending: Minimum radius = 4x pipe diameter.
- Painting: Apply zinc-rich primer (5 µm) + epoxy (25 µm).
Quality Assurance
- Coating Thickness Test: Magnetic induction gauge (ISO 2178).
- Hydrostatic Pressure: 6.9 MPa held for 30 sec (API 5L).
- Certifications: PED 2014/68/EU, ISO 9001:2015, and RoHS.
Competitive Edge
- Lifespan: 25–40 years in coastal/industrial zones.
- Lead Time: 15–20 days (MOQ 3 tons).
- Sustainability: 100% recyclable with 20% lower CO₂ vs. stainless steel.
Logistics & Compliance
- Packaging: VCI paper + steel straps (ISPM15 compliant).
- Temperature Range: -30°C to 450°C (HDG), 0°C to 200°C (EG).
- Optional Coatings: Aluminized-silicon or PTFE upon request.
Logical Connectors:
- Comparison: While electroplating suits indoor use, HDG excels in marine environments.
- Example: For instance, HDG pipes are used in Baltic Sea oil platforms.
- Cause-Effect: Z450 coating (85 µm) prevents rust in saltwater splash zones.
Comparative Analysis
| Material | Corrosion Resistance | Max Temp (°C) | Key Applications |
|---|---|---|---|
| HDG Welded | Extreme (2,000 hrs) | 450 | Offshore rigs, Bridges |
| Cold-Galvanized | Moderate (250 hrs) | 120 | Indoor electrical conduits |
| PVC Schedule 80 | High | 60 | Chemical drainage |
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