The Hot Dip Galvanized Hex Bolt is an heavy-duty structural fastener specifically engineered for harsh outdoor environments, power distribution lines, solar mounting frameworks, and marine infrastructure. Fabricated from premium carbon steel (Q235B or 45# steel) and treated through molten zinc immersion according to BS EN ISO 1461 standards, this fastener delivers an exceptionally thick, metallurgically bonded zinc barrier that ensures decades of maintenance-free corrosion resistance in accordance with international ISO standards.
Technical Specifications of Hot Dip Galvanized Hex Bolt
Hot-dip galvanizing (HDG) deposits a thick alloyed zinc coating (typically 45 microns to over 85 microns thick) that provides cathodic sacrificial protection to the underlying steel core. We manufacture HDG hex bolts in Class 4.8 for standard utility structures and Grade 8.8 quenched and tempered steel for load-bearing high-tensile installations.
| Parameter | Class 4.8 HDG Hex Bolt | Grade 8.8 HDG High Tensile Hex Bolt |
|---|---|---|
| Core Material | Low Carbon Steel (Q195 / Q235B) | Medium Carbon / Alloy Steel (45# / 40Cr) |
| Tensile Strength | 400 N/mm² (Nominal) | 800 N/mm² (Nominal) |
| Galvanizing Standard | BS EN ISO 1461:2009 / ASTM A153 | BS EN ISO 1461:2009 / ASTM A153 |
| Zinc Coating Thickness | Average 45 µm – 65 µm (≥ 300 g/m²) | Average 65 µm – 85 µm (≥ 500 g/m²) |
| Thread Clearance / Fit | Undersized shank or over-tapped 6H nut fit | Undersized thread allowance for smooth fit post-HDG |
Hot Dip Galvanization Process for Hot Dip Galvanized Hex Bolt
At our Handan manufacturing plant, hot-dip galvanizing is performed through an integrated chemical and thermal immersion process to form zinc-iron intermetallic alloy layers:
- Cold Heading & Thread Pre-Cutting: Bolts are cold forged and threaded with precise pitch tolerances allowing for zinc thickness accumulation without thread jamming.
- Pickling & Flux Preparation: Blanks pass through hydrochloric acid pickling tanks and molten flux to eliminate iron oxides and ensure total metallurgical wetting.
- Molten Zinc Immersion (450°C): Bolts are submerged in molten zinc baths where iron reacts with zinc to form bonded Gamma, Delta, and Zeta alloy layers topped by pure Eta zinc.
- High-Speed Centrifugal Spin-Drying: Excess molten zinc on the thread profile is spun off instantly in a high-speed centrifuge, guaranteeing clean, smooth thread engagement.
Outdoor and Heavy Duty Applications of Hot Dip Galvanized Hex Bolt
Thanks to its unmatched resistance to atmospheric weathering, acid rain, and salt spray corrosion, hot-dip galvanized hex bolts are widely specified in critical outdoor infrastructure:
- Overhead Power Lines & Substation Fittings: Fastening pole line hardware, crossarm brackets, strain clamps, and transformer platforms.
- Solar PV Mounting Systems: Anchoring ground-mounted solar racking, aluminum rails, and tracker frame brackets.
- Highway & Civil Engineering: Guardrail posts, steel bridges, cable tray supports, and outdoor signage structures.
Quality Control and Export Packaging for Hot Dip Galvanized Hex Bolt
Handan YiHao Fastener enforces strict Quality Assurance (QA) protocols for all export shipments. Magnetic thickness gauges measure zinc layer depth across head flats and shank sections, while thread ring gauges ensure effortless spin-on assembly with hot-dip galvanized DIN 934 hex nuts.
Export orders are packed in heavy-duty 25kg inner cartons, neatly stacked on ISPM 15 compliant fumigated wooden pallets, and wrapped in protective stretch film to ensure safe maritime delivery.
Request Factory Direct Pricing for Hot Dip Galvanized Hex Bolts
Looking for a reliable manufacturer in Handan, China for Class 4.8 or Grade 8.8 hot dip galvanized hex bolts? Contact Handan YiHao Fastener today for technical datasheets, zinc coating test reports, full thread/partial thread options, and competitive bulk export quotes.
