Product Introduction
Heavy hexagon nuts manufactured to GB/T 6175, the Chinese national standard dimensionally aligned with ISO 4033. The increased nut height provides greater thread engagement length and higher proof load values than standard series nuts. Commonly paired with property class 8.8, 10.9, and 12.9 bolts in preloaded structural and mechanical joints. Additional conformance to DIN, ISO, ANSI, JIS, and ASTM is supplied per customer specification.

Material & Mechanical Properties
Formed from carbon steel and quench-and-tempered for property classes 8, 10, and 12 under ISO 898-2. Proof load testing and hardness are certified by production lot, with heat-number traceability. The heavy hex design ensures that the nut consistently carries the full proof stress of the corresponding bolt grade without thread stripping or plastic deformation.

Geometry & Thread
Internal ISO metric coarse thread per GB/T 196 / ISO 724. The external hexagonal dimensions follow GB/T 6175 wrench opening requirements and are fully compatible with standard open-end, ring, and socket tools. A chamfered bearing surface and lead-in thread protect bolt threads during assembly.

Corrosion Protection
Zinc electroplated to GB/T 5267.1 (ISO 4042) provides effective corrosion resistance for indoor and covered outdoor environments. For structural applications and aggressive atmospheres, hot-dip galvanized, zinc-nickel, or zinc flake finishes are specified. Galvanized nuts are overtapped to accommodate the bolt’s coating allowance and ensure free assembly.

Application Suitability
Structural steel erection, heavy machinery frames, pressure vessel bolting, pipe flanges, and general fabrication where a heavy series hex nut is required for enhanced load distribution and joint integrity. Available in metric coarse sizes M6–M64 and to customer-specific dimensions, plating, and packaging requirements.