Galvanized Hex Bolt to GB/T 5780 (Product Grade C, Class 4.8)
Galvanized Hex Bolt to GB/T 5780 (Product Grade C, Class 4.8)
Thegalvanized hex bolt to GB/T 5780 is a product grade C hexagon head bolt in property class 4.8, supplied in galvanized carbon steel for ship cargo hold and general marine structural fastening. It is used together with a GB/T 41 hex nut and hardened washers to form a complete bolting assembly, and is one of the most common standard fixings specified by domestic shipyards for hold fittings and light steel structures.
What Is a GB/T 5780 Hex Bolt?
GB/T 5780 specifies hexagon head bolts of product grade C, a commercial grade used where a bearing surface and threaded length are required but where fit tolerances are not critical. Class 4.8 means a nominal tensile strength of 400 MPa and a yield ratio of 0.8 (yield strength approx. 320 MPa). Grade C bolts have larger dimensional tolerances than grade A/B bolts and are typically supplied with full dimple washers, making them economical for general marine assembly work.
Marine Applications
Note: the following applications are based on typical industry practice for shipyard standard fixings; actual use should follow the vessel design documents.
| Application | Typical Size |
|---|---|
| Cargo hold lashing and securing fittings | M16×55 – M16×75 |
| Hold floor plate and shear plate fixings | M12×55 |
| Pipe and equipment support brackets | M12 – M20 |
Specifications & Materials
| Parameter | Range | Standard Reference |
|---|---|---|
| Nominal thread size | M10 – M36 (typical hold sizes M12 – M20) | GB/T 5780 |
| Thread pitch | Coarse pitch per standard | GB/T 193 |
| Bolt length range | 40 – 200 mm | GB/T 5780 |
| Property class | 4.8 (yield ≈ 320 MPa) | GB/T 3098.1 |
| Material | Galvanized carbon steel | GB/T 700 / GB/T 3098.1 |
| Surface finish | Electroplated or hot-dip galvanized | GB/T 5267.1 / GB/T 13912 |
Why Choose sinofastener for Your Hex Bolts?
36 years of fastener manufacturing experience, founding year 1990, with an annual capacity of 50,000 tons covering full-range standard fasteners M12–M64.
Full GB series supply – we support GB/T 5780 bolts, GB/T 41 nuts and GB/T 93 washers as matched sets for shipyard hold packages.
Traceable material certificates with third-party inspection on request.
Coast-to-export logistics for shipbuilding and offshore projects.
Standards Reference
- GB/T 5780 – Hexagon head bolts, product grade C
- GB/T 3098.1 – Mechanical properties of fasteners, bolts/screws/studs
- GB/T 193 – Metric coarse pitch threads
- GB/T 5267.1 – Electroplated coating, or GB/T 13912 – Hot dip galvanizing
FAQ
What is the difference between GB/T 5780 and GB/T 5782?
GB/T 5780 is product grade C (larger tolerances, commercial use), while GB/T 5782 is product grade A/B with tighter tolerances for more exacting applications. Grade C is the economical choice for general hold and structural fixings.
Is the 4.8 class suitable for cargo hold fittings?
4.8 is commonly used for non-critical hold plates, brackets and lashing-type fixings where design loads are moderate, per typical shipyard practice. Load-critical connections follow the design specification.
Can you supply bolts and nuts as a matched set?
Yes. We supply GB/T 5780 bolts together with matching GB/T 41 nuts and washers as complete assemblies, sized to your bill of materials.
Contact Us
Email: sales@sinofastener.com | bobo@sinofastener.com
Tel: 0574-86592068
Website: www.zlfastener.com | www.sinofastener.com (Main)
